Patent Grant
11958288
The present invention relates to systems and methods for controlling various aspects of a digital printing system that uses an intermediate transfer member. In particular, the present invention is suitable for printing systems in which a liquid formulation is applied to the intermediate transfer member.
Various printing devices use an inkjet printing process, in which an ink is jetted to form an image onto the surface of an intermediate transfer member (ITM), which is then used to transfer the image onto a substrate. The ITM may be a rigid drum or a flexible belt (e.g. guided over rollers or mounted onto a rigid drum). Sometimes it can be desirable to apply a liquid solution to the surface of the ITM, for example a treatment solution to improve the quality of the image that is printed onto the surface of the ITM and transferred thence to a substrate. A liquid solution can be applied in excess of the final desired thickness, in which case doctor blades can be used to remove the excess. Such doctor blades have to be cleaned from time to time, to assure proper and continuous application of the liquid solution during the operation of the printing press. In order to facilitate the cleaning of the blades it can be advantageous to replace the blades from time to time, but preferably only in accordance with instructions carried out by a blade-replacement controller.
The following co-pending patent publications provide potentially relevant background material, and are all incorporated herein by reference in their entirety: WO/2017/009722 (publication of PCT/IB2016/053049 filed May 25, 2016), WO/2016/166690 (publication of PCT/IB2016/052120 filed Apr. 4, 2016), WO/2016/151462 (publication of PCT/IB2016/051560 filed Mar. 20, 2016), WO/2016/113698 (publication of PCT/IB2016/050170 filed Jan. 14, 2016), WO/2015/110988 (publication of PCT/IB2015/050501 filed Jan. 22, 2015), WO/2015/036812 (publication of PCT/IB2013/002571 filed Sep. 12, 2013), WO/2015/036864 (publication of PCT/IB2014/002366 filed Sep. 11, 2014), WO/2015/036865 (publication of PCT/IB2014/002395 filed Sep. 11, 2014), WO/2015/036906 (publication of PCT/IB2014/064277 filed Sep. 12, 2014), WO/2013/136220 (publication of PCT/IB2013/051719 filed Mar. 5, 2013), WO/2013/132419 (publication of PCT/IB2013/051717 filed Mar. 5, 2013), WO/2013/132424 (publication of PCT/IB2013/051727 filed Mar. 5, 2013), WO/2013/132420 (publication of PCT/IB2013/051718 filed Mar. 5, 2013), WO/2013/132439 (publication of PCT/IB2013/051755 filed Mar. 5, 2013), WO/2013/132438 (publication of PCT/IB2013/051751 filed Mar. 5, 2013), WO/2013/132418 (publication of PCT/IB2013/051716 filed Mar. 5, 2013), WO/2013/132356 (publication of PCT/IB2013/050245 filed Jan. 10, 2013), WO/2013/132345 (publication of PCT/IB2013/000840 filed Mar. 5, 2013), WO/2013/132339 (publication of PCT/IB2013/000757 filed Mar. 5, 2013), WO/2013/132343 (publication of PCT/IB2013/000822 filed Mar. 5, 2013), WO/2013/132340 (publication of PCT/IB2013/000782 filed Mar. 5, 2013), and WO/2013/132432 (publication of PCT/IB2013/051743 filed Mar. 5, 2013).
The following co-pending applications are all incorporated herein by reference in their entirety: PCT application PCT/IB2017/053177, filed May 30, 2017, and PCT application PCT/IL2017/050616, filed Jun. 1, 2017.
The present disclosure relates to printing systems and methods of operating printing systems, for example, a digital printing system having a moving intermediate transfer member (ITM) such as, for example, a flexible ITM (e.g. a blanket) mounted over a plurality of rollers (e.g. a belt) or mounted over a rigid drum (e.g. a drum-mounted blanket).
An ink image is formed on a surface of the moving ITM (e.g. by droplet deposition at an image-forming station) and subsequently transferred to a substrate, which can comprise a paper, a plastic, a metal, or any other suitable material. To transfer the ink image to the substrate, substrate is pressed between at least one impression cylinder and a region of the moving ITM where the ink image is located, at which time the transfer station (also called an impression station) is said to be engaged.
For flexible ITMs mounted over a plurality of rollers, an impression station typically comprises, in addition to the impression cylinder, a pressure cylinder or roller, the outer surface of which may optionally be compressible. The flexible blanket or belt passes in between such two cylinders which can be selectively engaged or disengaged, typically when the distance between the two is reduced or increased. One of the two cylinders may be at a fixed location in space, the other one moving toward or apart of it (e.g. the pressure cylinder is movable or the impression cylinder is movable) or the two cylinders may each move toward or apart from the other. For rigid ITMs, the drum (upon which a blanket may optionally be mounted) constitutes the second cylinder engaging or disengaging from the impression cylinder.
For the sake of clarity, the word rotation is used herein to denote the movement of an ITM in a printing press in a print direction, regardless of whether the movement is at various places in the printing press locally linear or locally rotational or otherwise. For rigid ITMs having a drum shape or support, the motion of the ITM is rotational. The print direction is defined by the movement of an ink image from an image forming station to an impression station. Unless the context clearly indicates otherwise, the terms upstream and downstream as may be used hereinafter relate to positions relative to the printing direction.
Some embodiments relate to printing systems, and in particular printing systems that comprise an intermediate transfer member (ITM) comprising a flexible endless belt mounted over a plurality of guide rollers, and also comprising first and second pluralities of pre-determined sections, an image forming station configured to form ink images upon a surface of the ITM, a conveyer for driving rotation of the ITM to transport the ink images towards an impression station where they are transferred to substrate, and a treatment station disposed downstream of the impression station and upstream of the image forming station configured for coating the ITM surface with a layer of a liquid treatment formulation, wherein the treatment station can comprise an applicator for applying the liquid treatment formulation to the ITM, a coating thickness-regulation assembly comprising a plurality of blades, the assembly configured so that for at least a part of the time each one of the blades is in an active position for removing excess liquid from a section of the ITM as the ITM section traverses a fixed excess-removal location so as to leave only the desired layer of treatment formulation, a blade-replacement mechanism, associated with the coating thickness-regulation assembly and configured for performing blade-replacement operations to replace a blade in the active position with another blade; and a blade-replacement controller for controlling the blade-replacement mechanism to ensure that the blade-replacement operations are performed only when one of the first plurality of pre-determined sections of the ITM traverses the excess-removal location.
In some embodiments, a printing system can comprise an intermediate transfer member (ITM) comprising a flexible endless belt mounted over a plurality of guide rollers (an ITM can comprise first and second pluralities of pre-determined sections), an image forming station configured to form ink images upon a surface of the ITM, a conveyer for driving rotation of the ITM to transport the ink images towards an impression station where they are transferred to substrate, and a treatment station disposed downstream of the impression station and upstream of the image forming station configured for coating the ITM surface with a layer of a liquid treatment formulation, wherein the treatment station can comprise an applicator for applying the liquid treatment formulation to the ITM, a coating thickness-regulation assembly comprising a plurality of blades, the assembly configured so that for at least a part of the time each one of the blades is in an active position for removing excess liquid so as to leave only the desired layer of treatment formulation, a blade-replacement mechanism, associated with the coating thickness-regulation assembly and configured for performing blade-replacement operations to replace a blade in the active position with another blade; and a blade-replacement controller for controlling the blade-replacement mechanism to ensure that the blade-replacement operations are performed only when one of the first plurality of pre-determined sections of the ITM traverses the excess-removal location.
In some embodiments, a printing system can comprise an intermediate transfer member (ITM) comprising a flexible endless belt mounted over a plurality of guide rollers (an ITM can comprise first and second pluralities of pre-determined sections), an image forming station configured to form ink images upon a surface of the ITM, a conveyer for driving rotation of the ITM to transport the ink images towards an impression station where they are transferred to substrate, and a treatment station disposed downstream of the impression station and upstream of the image forming station configured for applying a layer of a liquid treatment formulation on the ITM surface, wherein the treatment station can comprise an applicator for applying the liquid treatment formulation to the ITM, a coating thickness-regulation assembly comprising a plurality of blades (the assembly can be configured so that for at least a part of the time each one of the blades is in an active position for removing excess liquid from a section of the ITM as the ITM section traverses a fixed excess-removal location so as to leave only the desired layer of treatment formulation), a blade-replacement mechanism associated with the coating thickness-regulation assembly and configured for performing blade-replacement operations to replace a blade in the active position with another blade, and a blade-replacement controller for controlling the blade-replacement mechanism to avoid performing blade-replacement operations when one of the second plurality of pre-determined sections of the ITM traverses the excess-removal location.
In some embodiments, a printing system can comprise an intermediate transfer member (ITM) comprising a flexible endless belt mounted over a plurality of guide rollers (an ITM can comprise first and second pluralities of pre-determined sections), an image forming station configured to form ink images upon a surface of the ITM, a conveyer for driving rotation of the ITM to transport the ink images towards an impression station where they are transferred to substrate, and a treatment station disposed downstream of the impression station and upstream of the image forming station configured for applying a layer of a liquid treatment formulation on the ITM surface, wherein the treatment station can comprise an applicator for applying the liquid treatment formulation to the ITM, a coating thickness-regulation assembly comprising a plurality of blades (the assembly can be configured so that for at least a part of the time each one of the blades is in an active position for removing excess liquid from a section of the ITM as the ITM section traverses a fixed excess-removal location so as to leave only the desired layer of treatment formulation), a blade-replacement mechanism associated with the coating thickness-regulation assembly and configured for performing blade-replacement operations to replace a blade in the active position with another blade, and a blade-replacement controller for controlling the blade-replacement in accordance with a timing scheme. The timing scheme can mean that the blade-replacement controller can control the blade-replacement to perform a blade-replacement operation exactly once during each rotation of the ITM.
In embodiments of the printing system, the blade-replacement controller can control the blade-replacement mechanism to perform the blade-replacement operations only when a pre-selected one of the first plurality of pre-determined sections of the ITM traverses the excess-removal location. In some embodiments, the blade-replacement controller can additionally or alternatively control the blade-replacement mechanism to avoid performing blade-replacement operations while ink images are being transferred to a sheet of substrate at the impression station. In some embodiments, the blade-replacement controller may additionally or alternatively control the blade-replacement mechanism in accordance with a timing scheme.
In some embodiments, the printing system can additionally comprise a plurality of input devices configured to communicate with the blade-replacement controller. The blade-replacement controller can control the blade-replacement mechanism according to ITM-panel position information communicated thereto from an input device.
As mentioned above with respect to certain embodiments, an ITM can comprise first and second pluralities of pre-determined sections. The second plurality of pre-determined sections can include sections of the ITM which comprise ink-image areas. The second plurality of pre-determined sections can include a section of the ITM that comprises a seam. In some embodiments, the first and second pluralities are mutually exclusive, and in some embodiments the first and second pluralities together comprise all the sections of the ITM.
In some embodiments, the coating thickness-regulation assembly can comprise a blade-holder, which can be rotatable, and which can be a cylinder or a polygonal cylinder, and which can have the blades arranged so as to be radially extended from the blade-holder. A blade-replacement mechanism according to embodiments can comprise a motor, for example a DC motor or an AC motor. In some embodiments, the blade-replacement operation comprises rotating the coating-thickness-regulation assembly.
In embodiments, the coating thickness-regulation assembly and the blade-replacement mechanism can be configured so that at a first time before a blade-replacement operation, only a first blade is in the active position, at a second time during a blade-replacement operation, the first blade and a second blade are both in the active position, and at a third time after a blade-replacement operation, only the second blade is in the active position.
In some embodiments, the blade-replacement controller can control the blade-replacement to perform a blade-replacement operation exactly once during each rotation of the ITM. In some embodiments, the blade-replacement controller can comprise a non-transitory computer-readable medium containing program instructions, wherein execution of the program instructions by one or more processors of a computer system can cause the one or more processors to carry out at least one of causing the blade-replacement mechanism to perform a blade-replacement operation only when one of the first plurality of pre-determined sections of the ITM traverses the excess-removal location, and causing the blade-replacement mechanism to avoid performing a blade-replacement operation when one of the second plurality of pre-determined sections of the ITM traverses the excess-removal location.
In embodiments, a method of operating a printing system—a printing system wherein ink images are formed upon a surface of a rotating intermediate transfer member (ITM) by droplet deposition, transported towards an impression station and transferred to substrate, and wherein the printing system includes a blade-replacement mechanism and a blade-replacement controller—can comprise applying an excess of liquid treatment formula to a section of the surface of the rotating ITM downstream of the impression station, transporting the section of the ITM with an excess of liquid treatment formulation past an excess-removal location where the presence, in an active position, of one of a plurality of blades causes excess liquid to be removed, and performing a blade-replacement operation in accordance with a control function. The control function can be performed by a blade-replacement controller that controls the operation of a blade-replacement mechanism to ensure that replacement of a blade in the active position with a different blade takes place only when the section of the ITM being transported past the excess-removal location is one of a plurality of pre-determined sections. In some embodiments of the method the printing system additionally comprises a plurality of input devices, and in some embodiments, the performing of a blade-replacement operation in accordance with a control function can comprise receiving at least one of location information and ITM rotation speed information from one or more input devices, determining (using the at least one of location information and ITM rotation speed information received from the one or more input devices), whether a section of the ITM is one of a plurality of pre-determined sections of the ITM, and initiating a blade-replacement operation by the blade-replacement mechanism based on the determining.
In some embodiments of the method, the performing a blade-replacement operation in accordance with a control function can comprise determining whether a section of the ITM fulfills a control function rule for performance of a blade-replacement operation, and can also comprise initiating a blade-replacement operation by the blade-replacement mechanism based on the determining. In some embodiments, performing a blade-replacement operation in accordance with a control function can additionally comprise retrieving the control function rule from computer storage.
According to embodiments of the method, the control function rule can be included in program instructions executed by one or more processors of the blade-replacement controller.
According to some embodiments, the blade-replacement controller can control the blade-replacement mechanism to perform the blade-replacement operations only when the section of the ITM being transported past the excess-removal location is a pre-selected one of a plurality of pre-determined sections. According to some embodiments, the blade-replacement controller can additionally control the blade-replacement mechanism to avoid performing blade-replacement operations while ink images are being transferred to a sheet of substrate at the impression station. In some embodiments of the method, the blade-replacement controller controls the blade-replacement mechanism in accordance with a timing scheme.
According to embodiments of the method, the printing system can include a coating thickness-regulation assembly that comprises a blade-holder (which can comprise a cylinder or polygonal cylinder and can be rotatable), where each of the plurality of blades is radially extended from the blade-holder, the blade-replacement mechanism can comprise a motor, and the blade-replacement operation can comprise rotating the coating-thickness-regulation assembly.
In embodiments of the method, the coating thickness-regulation assembly and the blade-replacement mechanism can be configured so that at a first time before a blade-replacement operation, only a first blade is in the active position, and then at a second time during a blade-replacement operation, the first blade and a second blade are both in the active position, and then at a third time after a blade-replacement operation, only the second blade is in the active position. In some embodiments, the blade-replacement controller can control the blade-replacement operation so as to enforce a rule whereby a blade-replacement operation is performed exactly once during each rotation of the ITM.
In some embodiments of the method, the ITM can comprise first and second pluralities of pre-determined sections, where the first and second pluralities are mutually exclusive and together comprise all the sections of the ITM. In these embodiments, the blade-replacement controller can comprise a non-transitory computer-readable medium containing program instructions, wherein execution of the program instructions by one or more processors of a computer system causes the one or more processors to carry out at least one of causing the blade-replacement mechanism to perform a blade-replacement operation only when one of the first plurality of pre-determined sections of the ITM traverses the excess-removal location, and causing the blade-replacement mechanism to avoid performing a blade-replacement operation when one of the second plurality of pre-determined sections of the ITM traverses the excess-removal location.
In embodiments, a printing system can comprise an intermediate transfer member (ITM) comprising a flexible endless belt, an image forming station configured to form ink images by droplet deposition upon a surface of the ITM moving through the image forming station, an impression station where the ink images are transferred to substrate from the ITM surface, a conveyer for driving rotation of the ITM to transport the ink images towards the impression station, a treatment station disposed downstream of the impression station and upstream of the image forming station configured for coating the ITM surface with a layer of a liquid treatment formulation—where the treatment station can comprise an applicator for applying the liquid treatment formulation to the surface of the ITM, and a coating thickness-regulation assembly comprising a blade, the blade disposed so that a tip of the blade removes excess treatment formulation from the surface of the portion of the ITM traversing the treatment station to leave only the desired layer of treatment formulation—and a controller configured to detect a non-uniform stretching of the ITM associated with the traversal of the treatment station by the portion of the ITM and respond by modulating a timing of the droplet deposition so as to compensate for the non-uniform stretching. In some embodiments, the non-uniform stretching is caused by the interaction of the blade with the surface of the ITM.
In embodiments, a printing system can comprise an intermediate transfer member (ITM) comprising a flexible endless belt, an image forming station configured to form ink images by droplet deposition upon a surface of the ITM moving through the image forming station, an impression station where the ink images are transferred to substrate from the ITM surface, a conveyer for driving rotation of the ITM to transport the ink images towards the impression station, a treatment station disposed downstream of the impression station and upstream of the image forming station configured for coating the ITM surface with a layer of a liquid treatment formulation—where the treatment station can comprise an applicator for applying the liquid treatment formulation to surface of the ITM, and a coating thickness-regulation assembly comprising a blade, the blade disposed so that a tip of the blade interacts with the surface of the ITM so as to remove excess treatment formulation from the surface of the ITM and leave only the desired layer of treatment formulation—and a controller configured to detect a non-uniform stretching of the ITM caused by the interaction of the blade with the surface of the ITM and respond by modulating a timing of the droplet deposition so as to compensate for the non-uniform stretching caused by the interaction of the blade with the surface of the ITM.
In any of the foregoing printing systems, the controller can additionally be configured to report detections of non-uniform stretching to an operator or to a log file. The coating thickness-regulation assembly can additionally comprise at least one additional blade and be configured so that for at least a part of the time each one of the blades is in an active position to interact physically with the surface of the ITM so as to remove excess treatment formulation from the surface of the ITM.
In embodiments, a printing system can comprise an intermediate transfer member (ITM) comprising a flexible endless belt, an image-forming station configured to form ink images by droplet deposition upon a surface of the ITM moving through the image forming station, an impression station where the ink images are transferred to substrate from the ITM surface, a conveyer for driving rotation of the ITM to transport the ink images towards the impression station, a treatment station disposed downstream of the impression station and upstream of the image-forming station configured for coating the ITM surface with a layer of a liquid treatment formulation—wherein the treatment station comprises an applicator for applying the liquid treatment formulation to the ITM, a coating thickness-regulation assembly comprising a plurality of blades, the assembly configured so that for at least a part of the time each one of the blades is in an active position, so as to leave only the desired layer of treatment formulation on the surface of the ITM as it traverses the blade in the active position, and a blade-replacement mechanism, associated with the coating thickness-regulation assembly and configured for performing blade-replacement operations to replace a blade in the active position with another blade, wherein a blade-replacement operation causes a local stretching of the ITM proximate to the portion of the ITM passing a blade in the active position—and a controller configured to detect said local stretching of the ITM and respond by modulating a timing of the droplet deposition so as to compensate for said local stretching of the ITM. In some embodiments, the local stretching of the ITM can be propagated to another part of the ITM and not be manifested proximate the portion of the ITM passing a blade in the active position.
In the foregoing printing systems, the modulating can be delayed by the travel time of the non-uniformly stretched section of the ITM between the treatment station and the image-forming station.
In embodiments, a method of operating a printing system wherein ink images are formed upon a surface of a rotating intermediate transfer member (ITM) by droplet deposition, transported towards an impression station and transferred to substrate, and wherein the printing system includes a coating thickness-regulation assembly comprising a blade, can comprise using a coating applicator, applying an excess of liquid treatment formula to a section of the surface of the rotating ITM downstream of the impression station, transporting the section of the ITM with an excess of liquid treatment formulation past an excess-removal location where the presence of a blade causes excess liquid to be removed by interaction between the blade and the ITM and responsively to a detection of a non-uniform stretching of the ITM, modulating a timing of the droplet deposition so as to compensate for the non-uniform stretching. In some embodiments, the non-uniform stretching is caused by the interaction of the blade with the surface of the ITM.
In embodiments, a method of operating a printing system wherein ink images are formed upon a surface of a rotating intermediate transfer member (ITM) by droplet deposition, transported towards an impression station and transferred to substrate, and wherein the printing system includes a coating thickness-regulation assembly comprising a blade, can comprise using a coating applicator, applying an excess of liquid treatment formula to a section of the surface of the rotating ITM downstream of the impression station, transporting the section of the ITM with an excess of liquid treatment formulation past an excess-removal location where the presence of a blade causes excess liquid to be removed by interaction between the blade and the ITM and responsively to a detection of a non-uniform stretching of the ITM caused by the interaction of the blade with the surface of the ITM, modulating a timing of the droplet deposition so as to compensate for the non-uniform stretching caused by the interaction of the blade with the surface of the ITM.
In some embodiments, the method additionally comprises the step of responsively to the detection of repeated non-uniform stretchings of the ITM, adjusting the physical position of the blade. In some embodiments, the detection of the non-uniform stretching of the ITM is done by a controller of the printing system. The controller can be additionally configured to report detections of non-uniform stretching to an operator or to a log file.
In embodiments, a method of operating a printing system wherein the printing system includes a rotating intermediate transfer member (ITM) upon which ink images are formed at an image-forming station by droplet deposition, and additionally includes a treatment station upstream of the image-forming station—wherein the treatment station comprises a coating applicator for applying a liquid treatment formulation to the ITM, a coating thickness-regulation assembly comprising a plurality of blades, and a blade-replacement mechanism for performing blade-replacement operations so as to change which blade interacts with the ITM to remove excess liquid treatment formulation from the surface of the ITM—can comprise using the blade-replacement mechanism to perform blade-replacement operations, detecting local stretching of a portion of the ITM that either intersects or is proximate to the portion of the ITM passing the treatment station during a blade-replacement operation, wherein the local stretching is at least partially caused by the blade-replacement operation, and responding to a detection of said local stretching of the ITM by modulating a timing of the droplet deposition so as to compensate for said local stretching of the ITM. In some embodiments, the modulating can be delayed by the travel time of the non-uniformly stretched section of the ITM between the treatment station and the image-forming station.
According to embodiments, a method of operating a printing system wherein ink images are formed upon a surface of a rotating intermediate transfer member (ITM) by droplet deposition, transported towards an impression station and transferred to substrate, and wherein the printing system includes a coating thickness-regulation assembly comprising a blade, can comprise: using a coating applicator, applying an excess of liquid treatment formula to a section of the surface of the rotating ITM downstream of the impression station, transporting the section of the ITM with an excess of liquid treatment formulation past an excess-removal location where the presence of a blade causes excess liquid to be removed by interaction between the blade and the ITM, and, in response to the detection of non-uniform stretchings of the ITM, wherein the non-uniform stretchings are associated with the traversal of the excess-removal location by the section of the ITM, adjusting the position of the blade.
In some embodiments, a printing system can comprise an intermediate transfer member (ITM) comprising a flexible endless belt, an image forming station configured to form ink images by droplet deposition upon a surface of the ITM moving through the image forming station, an impression station where the ink images are transferred to substrate from the ITM surface, a conveyer for driving rotation of the ITM to transport the ink images towards the impression station, a treatment station disposed downstream of the impression station and upstream of the image forming station configured for coating the ITM surface with a layer of a liquid treatment formulation—wherein the treatment station can comprise an applicator for applying the liquid treatment formulation to the surface of the ITM, and a coating thickness-regulation assembly comprising a blade, the blade disposed so that a tip of the blade removes excess treatment formulation from the surface of the portion of the ITM traversing the treatment station to leave only the desired layer of treatment formulation—and a controller configured to detect a non-uniform stretching of the ITM associated with the traversal of the treatment station by the portion of the ITM and respond by adjusting the position of the blade or by reporting to an operator or to a log file that a blade-position adjustment is recommended.
The invention will now be described further, by way of example, with reference to the accompanying drawings, in which the dimensions of components and features shown in the figures are chosen for convenience and clarity of presentation and not necessarily to scale. In the drawings:
The invention is herein described, by way of example only, with reference to the accompanying drawings. With specific reference now to the drawings in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present invention only, and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for a fundamental understanding of the invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the invention may be embodied in practice. Throughout the drawings, like-referenced characters are generally used to designate like elements.
For convenience, in the context of the description herein, various terms are presented here. To the extent that definitions are provided, explicitly or implicitly, here or elsewhere in this application, such definitions are understood to be consistent with the usage of the defined terms by those of skill in the pertinent art(s). Furthermore, such definitions are to be construed in the broadest possible sense consistent with such usage.
“Control functions” as used herein means functions performed by a controller, including, but not exhaustively: retrieving data from computer storage; retrieving system operating rules from computer storage (also called “rules” or “control function rules”); applying rules; receiving data from input devices; executing program instructions; making calculations, determinations and decisions by executing program instructions; and transmitting electronic or electrical signals to printing system components to initiate, modify or stop an operation.
A “controller” as used herein is intended to describe any processor, or computer comprising one or more processors, configured to control one or more aspects of the operation of a printing system or of one or more printing system components according to program instructions that can include rules, machine-learned rules, algorithms and/or heuristics, the programming methods of which are not relevant to this invention. A controller can be a stand-along controller with a single function as described, or alternatively can combine more than one control function according to the embodiments herein and/or one or more control functions not related to the present invention or not disclosed herein. For example, a single controller may be provided for controlling all aspects of the operation of a printing system, the control functions described herein being one aspect of the control functions of such a controller. Similarly, the functions disclosed herein with respect to a controller can be split or distributed among more than one computer or processor, in which case any such plurality of computers or processors are to be construed as being equivalent to a single computer or processor for the purposes of this definition. For purposes of clarity, some components associated with computer networks, such as, for example, communications equipment and data storage equipment, have been omitted in this specification but a skilled practitioner will understand that a controller as used herein can include any network gear or ancillary equipment necessary for carrying out the functions described herein.
In various embodiments, an ink image is first deposited on a surface of an intermediate transfer member (ITM), and transferred from the surface of the intermediate transfer member to a substrate (i.e. sheet substrate or web substrate). For the present disclosure, the terms “intermediate transfer member”, “image transfer member” and “ITM” are synonymous, and may be used interchangeably. The location at which the ink is deposited on the ITM is referred to as the “image forming station”. In many embodiments, the ITM comprises a “belt” or “endless belt” or “blanket” and these terms are used interchangeably with ITM. The area or region of the printing press at which the ink image is transferred to substrate is an “impression station”. It is appreciated that for some printing systems, there may be a plurality of impression stations.
For an endless intermediate transfer member, the “length” of an ITM is defined as the circumference thereof. An endless intermediate transfer member can be formed by joining two ends of a belt with a seam. A seam can be created by any method of joining the two ends of the belt depending on the materials used in the belt, and can include, for example: sewing, closing a zipper, using hook-and-loop fasteners, heat welding and ultrasonic welding, and can join the ends using, for example: rivets, screws, bolts, snaps, clips, fasteners comprising a metal, a plastic or a composite material, or an adhesive. These examples are not meant to be exhaustive but rather to illustrate the variety of joining methods available to the skilled practitioner.
Referring now to the figures,
In the example of
In the particular non-limiting example of
The skilled artisan will appreciate that not every component illustrated in
Examples of Doctor Blade Design and Function
The following paragraphs provide illustrative, non-limiting examples of the design and function of doctor blades according to various embodiments of the invention.
Prior to passing over the doctor blade 2014, the underside of the ITM 210 (or lower run) is coated with an excess of treatment formulation (e.g. solution) 2030. Neither the manner in which the excess of treatment formulation (e.g. solution) is applied to the ITM 210 nor the type of applicator used for coating is of fundamental importance to the present invention; the ITM 210 may for example simply be immersed in a tank containing the liquid, passed over a fountain 1128 of the treatment formulation (e.g. treatment solution) 2030 as shown in
As shown in the drawing, as the ITM 210 approaches the doctor blade 2014 it has a coating 2030 of liquid that is greater or significantly greater than the desired thickness. The function of the doctor blade 2014 is to remove excess liquid 2031 from the ITM 210 and ensure that the remaining liquid is spread evenly and uniformly over the entire surface of the ITM 210. In a non-limiting example, the doctor blade 2014 may be urged towards the ITM 210 while the latter is maintained under tension. For example, it may be urged towards the ITM 210 and thereby press ITM 210 against backing roller 1141. In another example, backing roller 1141 can be urged downward to provide additional force as ITM 210 traverses the doctor blade 2014. While shown as a cylindrical roller, backing roller 1141 can in fact have a flat, oval or oblong surface facing the ITM 210, the principle being that there is an object on the side of the ITM 210 opposite the doctor blade 2014 with a countering force or presence that increases the effectiveness of the excess-removal function of the doctor blade 2014. In some embodiments, the backing roller 1141 can have a soft or compressible surface or surface layer such that the tip of a doctor blade 2014 pushes the flexible ITM 210 to ‘penetrate’ or deform the surface backing roller 1141, as illustrated schematically in
The skilled practitioner will recognize that treatment solution can be applied to the ITM 210 by other means, and excess liquid 2031 can be removed by other means.
In another example of a treatment station illustrated schematically in
In embodiments, the tip of the doctor blade 2014 comprises a smooth rod 2022 with a uniform radius over the width of the ITM 210, and its smoothness ensures laminar flow of the liquid in the gap between it and the underside of the ITM 210. The nature of the flow may be similar to that of the liquid lubricant in a hydrodynamic bearing and reduces the film of liquid 2030 that remains adhering to the surface of the ITM 210 to a thickness dependent upon the force urging the ITM 210 against the doctor blade 2014 and the radius of curvature of the rod 2022. As both the radius and the force are constant over the width of the web, the resulting film is uniform and its thickness can be set by appropriate selection of the applied force and the rod diameter.
The tank 2016 into which the surplus treatment formulation (e.g. solution) falls may be the main reservoir tank from which liquid is drawn to apply treatment formulation 2030 to the underside of the web with an excess of treatment formulation 2030 (e.g. solution) or it may be a separate tank that is drained into a main reservoir tank (NOT SHOWN) and/or emptied to suitable discard systems (NOT SHOWN).
The rod 2022 is preferably made of a hard material such as, for example, a hardened steel or fused quartz to resist abrasion. There may be small particles of grit or dust in the liquid which could damage the rounded edge over which the liquid flows. In embodiments, the material should be capable of being formed into a smooth rod of uniform diameter or thickness, and a surface roughness where it contacts the ITM of less than 10 microns, in particular of less than 0.5 micron. The cross-section of the doctor rod 2022 can have a circular cross-section (in the plane orthogonal to a floor), or alternatively the cross-section can have any rounded shape, for example elliptical or oval, or have a rounded tip 1125 as illustrated in
Sometimes when using such a doctor blade in connection with the application of certain formulations (e.g. solution), a deposit 34 of the solute builds up on the downstream side of the doctor blade 2014, as schematically illustrated in
Changing or Replacing Doctor Blades
Embodiments of the invention relate to apparatus and methods for changing or replacing the doctor blade when it becomes soiled.
In the non-limiting example of
It will be obvious to the skilled practitioner that the blade-holder (e.g., the turret) may have a different configuration than that illustrated here without changing its function. For example, as illustrated in
In other embodiments, the replacement of blades can be accomplished with other arrangements that do not require the blade-holder to be rotatable.
The manner in which the turret 1120 and the doctor blades 1122 interact with the ITM 210 is shown in
In the example of
As the ITM 210 rotates and a portion of the ITM 210 traverses this excess-removal location in the direction indicated, it is this single one of the blades 1122ACTIVE that causes an excess of treatment formulation 2030 to be removed from the surface of the portion of the ITM 210.
The active doctor blade 1122ACTIVE (or a rounded tip 1125 thereof), together with the blade holder (in the figure, turret 1120) and other doctor blades 1122 not in an the active position, and backing roller 1141 (or alternatively a device for providing air pressure towards rounded tip 1125), collectively comprise a coating thickness-regulation assembly, in that the thickness of the treatment formulation 2030 remaining on the part of the ITM 210 that has traversed the excess-removal location may be regulated according to, inter alia, an amount of force F1 impelling the tip 1125 of active doctor blade 112ACTIVE towards the opposing portion of ITM 210, or vice versa. As shown earlier in
In the non-limiting example of
In some embodiments, prior to returning to the active position by successive blade-replacement operations in which the turret 1120 is rotated, i.e., at some later stage in the turret rotation cycle, a soiled blade 1122 passes through a cleaning device, for example a stationary or rotating brush 1130, as illustrated schematically in
In embodiments, the blade-replacement operation may be instigated on demand by an operator or it may be performed at regular intervals. In other embodiments, the blade-replacement operation can be controlled by a blade-replacement controller 1150 which applies a rule regarding when a blade-replacement operation takes place or doesn't take place. In some embodiments blade-replacement controller 1150 comprises a non-transitory computer-readable medium containing program instructions, wherein execution of the program instructions by one or more processors of a computer system causes the one or more processors to control when a blade-replacement mechanism performs or enables or facilitates a blade-replacement operation, or alternatively avoids or prevents a blade-replacement operation. The enablement or avoiding of a blade-replacement operation can be on the basis of timing, and it can be on the basis of what portion of the ITM 210 is allowed to be traversing or, alternatively, not allowed to be traversing, the excess-removal location at the time of the blade-replacement operation.
The number of doctor blades 1122 installed on the turret 1120 need not be twelve as has been shown, and any number of blades 1122 can be installed on the turret 1120. In some embodiments, it can be desirable for there to be a sufficient number so that during a changeover, i.e., a blade-replacement operation, there will be a time when two doctor blades 1122 are functional and interact with the ITM 210 (are ‘active’) at the same time and jointly occupy the excess-removal location. In this way, there is facilitated a substantially continuous transition from one blade being active to another being active, so that there need not be any interruption in operation of the coating thickness-regulation assembly, and this in turn permits a doctor blade 1122 to be changed without interruption of the printing system.
Referring now to
It should be clear to the skilled practitioner that the various examples described and illustrated herein for coating thickness-regulation assemblies and blade-replacement mechanism are not the only possible design choices possible for these components, as long as the basic principles of removing excess liquid (e.g., treatment formulation) and replacing blades in the active position are followed.
Referring now to
An ITM 210 can comprise any number of ITM panels, and the number of ITM panels may be selected in accordance with a specific design and size of a printing system. For example, an ITM 210 can comprise N panels 7001, 7002, 7003, . . . 700N. In some embodiments, each of the panels has the same panel length LP, as in the example illustrated in
An ITM panel 700 comprises an ink-image area 710, which is the area of an ITM panel on which an ink image is regularly formed on each pass of the panel through the image-forming station 212. For example, ITM panel 7001 comprises ink-image area 7101, ITM panel 7002 comprises ink-image area 7102, and so on up to N panels and N respective ink-image areas.
In some embodiments, an ITM panel 700 comprises a locator 720, used in locating ITM panels 700 relative to other components of a printing system 100. A locator 720 comprises one of a marker and an input device. A marker can be an optical marker, a magnetic marker, a mechanical marker or an electronic marker such as, for example, a radio frequency identification device (RFID). An input device can be a sensor or detector, for example a detector configured to detect a marker and/or to receive data communications from a marker. In some embodiments, each ITM panel comprises a marker as a locator 720, and in those embodiments a fixed locator 810 (discussed below with reference to
The rotation of an ITM panel 700 through the ITM rotation path can include at least two periods of time in a single printing cycle. During a first period, an ink-image area 710 comprises an ink image 711 (NOT SHOWN because each ink image 711 is coterminous with a respective ink-image area 710). As shown in
It can be desirable to avoid performing a blade-replacement operation as described above when a ‘sensitive’ section of an ITM is traversing the excess-removal location. The forces of the blade-replacement operation can put extra stress on the section of ITM passing over the tip of a doctor blade that is held in the active position, and can reduce the quality of the treatment formulation layer applied to the ITM (e.g. its uniformity, desired thickness, etc.), and therefore movement of the blades into and out of the active position should preferably take place when a sensitive section is not present. It should be noted that a blade-replacement operation is preferably performed very rapidly, for example in less than 100 milliseconds, in less than 50 milliseconds, or in less than 10 milliseconds, and this means that the blades are subjected to high acceleration and therefore high forces that can mechanically affect sensitive sections of the ITM with which the blades physically interact. An example of a sensitive section is a section that includes an ink-image area. Because ink-image areas are used repeatedly for formation of ink images thereupon, and because this usage entails not only the formation of ink images but also the transfer of images to substrate at an impression station where strong mechanical forces can be applied to effect the transfer, then the section including an ink-image area can be thinner, be more worn, exhibit material fatigue, or otherwise be less robust in terms of mechanical resistance to forces applied dynamically to its surface by a blade-replacement operation. In addition, the dynamic stress forces of a blade-replacement operation can have a deleterious effect on the future usefulness of a section of ITM that passes the active area during a blade-replacement operation, and thereby make the section less suitable mechanically in the future for repeated printing operations that including repeated ink image formation and repeated transfer to substrate by means of impressions at an impression station. The ITM could get stretched, thinned, frayed or otherwise damaged by experiencing repeated blade-replacement operations, and subsequently have a surface less conducive to being printed upon, or even have a shortened operational lifespan and require replacement sooner than it would otherwise have required. Moreover, it can be particularly important that the treatment formulation be as uniform as possible and as close as possible to the desired thickness specifically in the ink-image area, and, as noted earlier, the blade-replacement operation can locally affect the thickness and uniformity of the treatment formulation on the section of the ITM traversing the treatment station at the time of a blade-replacement operation. Another example of a sensitive section is a section that includes a seam. A seam subjected, whether once or repeatedly, to the stress forces of a blade-replacement operation may be weakened, or may rupture or fray or even be destroyed and rendered useless for further operation. Therefore, in some embodiments it may be desirable to control the occurrence of blade-replacement operations so as to avoid performing them during traversal by such sensitive ITM sections of the excess-removal location. In some embodiments, it may be desirable to control the occurrence of blade-replacement operations so as to ensure that they are performed only when non-sensitive sections of the ITM traverse the excess-removal location. In some embodiments, it may be desirable to control the occurrence of blade-replacement operations so as to ensure that they are performed only when a specific non-sensitive section of the ITM traverses the excess-removal location. There can be other sensitive sections in an ITM other than sections that include ink-image areas or seams, but for purposes of clarity only those two examples are used herein to explain the concept of sensitive sections. In some embodiments, it can be desirable to control the occurrence of blade-replacement so as to perform blade-replacement operations based on the timing of ink-image forming on the ITM. In some embodiments, it can be desirable to control the occurrence of blade-replacement so as to perform blade-replacement operations based on the timing of ink-image transfers from the ITM to the substrate.
Referring to
In
In
A printing system according to any of the embodiments herein comprises an ITM that includes 11 panels (i.e., N=11) and a seam between Panel 11 and Panel 1 (as illustrated in
A printing system according to any of the embodiments herein comprises an ITM that includes 11 panels and a seam between Panel 11 and Panel 1, each panel comprising an ink-image area, and the printing system additionally comprises a blade-replacement controller programmed to cause a blade-replacement mechanism to enforce a rule whereby a blade-replacement operation is performed exactly once during each rotation of the ITM, in this example after the ink-image area on Panel 11 has passed the excess-removal location, and before the seam passes it.
As discussed earlier, a sensitive section is one that contains, for example, an ink-image area or a seam. In embodiments, a controller uses location and/or speed information to determine when a section not comprising a sensitive section will pass the excess-removal location, and will only initiate a blade-replacement operation on the basis of that determining, thus ensuring that the section traversing the excess-removal location at the time of the blade-replacement operation is one of a plurality of pre-determined sections that do not include a sensitive section. In an embodiment, the method uses a blade-replacement controller that controls the blade-replacement mechanism to ensure that blade-replacement operations are only performed when one of a plurality of pre-determined sections of the ITM, for example the sections 750 of
In embodiments, such as those which will be discussed with reference to
In other embodiments, Step S06A comprises controlling the operation of the blade-replacement mechanism to ensure that replacement of a blade in the active position with a different blade takes place only when the section of the ITM being transported past the excess-removal location is one of a plurality of pre-determined ‘permissible’ sections of the ITM, i.e., they are pre-determined as permissible for blade-replacement operations. Examples of pre-determined ‘permissible’ sections include the sections 750 in
In other alternative embodiments, Step S06B comprises controlling the operation of the blade-replacement mechanism to avoid replacement of a blade in the active position with a different blade while the section of the ITM being transported past the excess-removal location is one of a plurality of pre-determined ‘non-permissible’ sections of the ITM, i.e., they are pre-determined as being non-permissible for blade-replacement operations. Examples of pre-determined ‘non-permissible’ sections include the sections 760 in
In some embodiments, not all steps of the method are necessary.
Examples of suitable apparatus for carrying out Steps S01, S02, S03, S04 and S05 have been described with reference to
In embodiments, either one of Step S06A or Step S06B can suitably be carried out by practicing a method for performing a blade-replacement operation in accordance with a control function, such as the method illustrated in the flowchart in
It will be obvious to the skilled practitioner that in some embodiments the retrieving (Step S07) can be skipped, for example: embodiments in which a control function rule is included in a controller's program instructions, or alternatively if a control function rule was retrieved earlier, for example when the printing system was first booted up. It will also be obvious to the skilled practitioner that the order of Decisions Q1 and Q2 can be reversed without changing the effectiveness of the method. In some embodiments, Decision Q1 can be skipped, and in other embodiments both the receiving (Step S08) and Decision Q1 can be skipped. In either of these two cases the initiating (Step S10) can proceed solely on the basis of a ‘YES’ result from Decision Q2. For the sake of clarity, a flowchart of the method according to an illustrative, non-limiting example of an embodiment, in which (Step S08) and Decision Q1 are both skipped, is included in
In other embodiments, Step S08 comprises determining when one of the plurality of pre-determined ‘permissible’ or ‘non-permissible’ sections of the ITM will pass the excess-removal location, using the at least one of location information and ITM rotation speed information received from the one or more input devices, and Step S10 comprises causing the blade-replacement operation to perform a blade-replacement operation according to the determining of Step S08.
Markers and input devices such as sensors or marker-detectors installed on an ITM, together with corresponding sensors or marker-detectors, or markers, respectively, installed in a printing system, can track the location of specific portions, sections and/or components of a rotating ITM. In an alternative embodiment, Step S08 comprises receiving location information from one or more such input devices, and the method comprises an additional Step S08.1 (NOT SHOWN) of calculating ITM speed from location information. A controller such as a blade-replacement controller 1150 receives location and, optionally, speed tracking information from input devices.
In embodiments, such as those which will be discussed with reference to
In some embodiments, not all steps of the method are necessary.
Examples of suitable apparatus for carrying out Steps S11, S12, S13, S14 and S15 have been described with reference to
In an alternative embodiment, Step S17 comprises receiving location information from one or more input devices, and the method comprises an additional Step S17.1 (NOT SHOWN) of calculating ITM speed from location information. A controller such as a blade-replacement controller 1150 receives location and, optionally, speed tracking information from input devices. The controller uses location and/or speed information to determine when the pre-selected section will pass the excess-removal location, and will initiate a blade-replacement operation on the basis of that determining. In an embodiment, the method uses a blade-replacement controller that controls the blade-replacement mechanism to ensure that blade-replacement operations occur only when the specific pre-selected section of the ITM, for example section 770 of
In embodiments, the blade-replacement controller 1150 is configured to ensure that blade-replacement operations do not occur synchronously with the transfer of an ink image 711 to substrate at an impression station 216. In some embodiments, this ensuring only takes place when the substrate comprises individual sheets.
As discussed earlier the tip 1125 (shown in
Local stretching of the ITM 210 can be caused by several factors or their combination. In a non-limiting example, the interaction between a doctor blade and the ITM can cause a local and/or non-uniform stretching of the ITM. This can occur because of the force F1 applied, or because of a frictional force between the ITM one the one hand and the doctor blade and/or the backing roller on the other hand, or a combination of the force F1 and the frictional force.
As shown in
The skilled practitioner will understand that the foregoing discussion referencing
The controller 215 can be additionally configured to respond to the detection of a non-uniform stretching of an ITM 210, by modulating a timing of the droplet deposition by the various print bars 222 so as to compensate for the non-uniform stretching. The modulating of the timing of the droplet deposition can be directed to avoid a mis-registration of ink droplets and avoid having the image-forming station 212 form a distorted ink image, or an image in which the various ink colors such as cyan, magenta, yellow and black (in a 4-color printing system, for example) do not line up properly to form an ink image as intended. Modulating the timing can include making the deposition of some ink droplets earlier or later than would otherwise have occurred. In some cases, modulating can include accelerating (making earlier) the deposition of some ink droplets of an image and decelerating (making later) the deposition of other ink droplets in the same image.
Suitable examples of methods for detecting non-uniform stretching of an ITM, and for responding to detecting non-uniform stretching of an ITM, include embodiments disclosed in US 2015/0042736 which is incorporated herein by reference in its entirety.
In some embodiments, the non-uniform stretching detected by the controller 215 is caused by the interaction between a blade 2014 or 1122, and the ITM 210. The nature of this interaction was discussed above with reference to
In some embodiments, the non-uniform stretching detected by the controller 215 can be caused by the additional stress of a blade-replacement operation. The details of blade-replacement operations have already been disclosed above, including the fact that they can cause stretching of an ITM 210, because a blade-replacement operation causes additional forces to be applied to the portion of the ITM 210 passing the treatment station when a blade-replacement operation occurs.
In some embodiments, the coating thickness-regulation assembly additionally comprises one or more additional blades, resulting in the coating thickness-regulation assembly comprising a plurality of blades, and the blade in Step S102 is one of the plurality of blades. In some embodiments, the non-uniform stretching is local and is within or proximate to the portion of the ITM traversing the treatment station. In some embodiments, not all steps of the method are necessary.
In some embodiments, the coating thickness-regulation assembly additionally comprises one or more additional blades, resulting in the coating thickness-regulation assembly comprising a plurality of blades, and the blade in Step S102A is one of the plurality of blades. In some embodiments, the non-uniform stretching is local and is within or proximate to the portion of the ITM traversing the treatment station. In some embodiments, not all steps of the method are necessary. In other embodiments, the local stretching of the ITM can be propagated to another part of the ITM that is not within or proximate to the portion of the ITM traversing the treatment station.
In some embodiments, the modulating of Step S113 can be delayed by the travel time of the non-uniformly stretched section of the ITM between the treatment station and the image-forming station.
The present invention has been described using detailed descriptions of embodiments thereof that are provided by way of example and are not intended to limit the scope of the invention. The described embodiments comprise different features, not all of which are required in all embodiments of the invention. Some embodiments of the present invention utilize only some of the features or possible combinations of the features. Variations of embodiments of the present invention that are described and embodiments of the present invention comprising different combinations of features noted in the described embodiments will occur to persons skilled in the art to which the invention pertains.
In the description and claims of the present disclosure, each of the verbs, “comprise”, “include” and “have”, and conjugates thereof, are used to indicate that the object or objects of the verb are not necessarily a complete listing of members, components, elements or parts of the subject or subjects of the verb. As used herein, the singular form “a”, “an” and “the” include plural references unless the context clearly dictates otherwise. For example, the term “a marking” or “at least one marking” may include a plurality of markings.
This patent application is a continuation of U.S. application Ser. No. 17/583,372 filed on Jan. 25, 2022, which is incorporated herein by reference in its entirety, U.S. application Ser. No. 17/583,372 is a continuation of U.S. application Ser. No. 16/764,330 which is a national-stage entry of PCT/IB2018/059032 which was filed on Nov. 16, 2018 and which is incorporated herein by reference in its entirety. PCT/IB2018/059032 claims the benefit of U.S. Provisional Patent Application No. 62/588,405 filed on Nov. 19, 2017, and of U.S. Provisional Patent Application No. 62/595,536 filed on Dec. 6, 2017, both of which are incorporated herein by reference in their entirety.
| Number | Name | Date | Kind |
|---|---|---|---|
| 11660856 | Pomerantz et al. | May 2023 | B2 |
| Number | Date | Country |
|---|---|---|
| 2009082835 | Apr 2009 | JP |
| 2012150390 | Aug 2012 | JP |
| Entry |
|---|
| JP2009082835A Machine Translation (by EPO and Google)—published Apr. 23, 2009; Fujifilm Corp. |
| JP2012150390A Machine Translation (by EPO and Google)—published Aug. 9, 2012; Konica Minolta Business Tech. |
| Number | Date | Country | |
|---|---|---|---|
| 20230364904 A1 | Nov 2023 | US |
| Number | Date | Country | |
|---|---|---|---|
| 62595536 | Dec 2017 | US | |
| 62588405 | Nov 2017 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 17583372 | Jan 2022 | US |
| Child | 18137488 | US | |
| Parent | 16764330 | US | |
| Child | 17583372 | US |
