EP3366481A1

EP3366481A1 - Printing system with a blouse forming device for stiff web media

Info

Publication number: EP3366481A1
Application number: EP18157654.7A
Authority: EP
Inventors: Maurice J.C. Lemmens; Peter J.W. VAN DONGEN
Original assignee: Oce Holding BV
Current assignee: Canon Production Printing Holding BV
Priority date: 2017-02-24
Filing date: 2018-02-20
Publication date: 2018-08-29
Anticipated expiration: 2038-02-20
Also published as: EP3366481B1

Abstract

The invention relates to a web printing system (1) configured for forming a blouse in a stiff or rigid medium. The printing system comprises a blouse forming region (B) positioned below a transport path (P). A pressing device (40) is provided moveable along a guide (44) between a first position (40A)above the transport path (P), and a second position (40B) below the transport path (P) in an upper zone of the blouse forming region. A locking device (42) is provided for holding the pressing device (40) at the second position (40B). The movement of the pressing device from the first position to the second position presses the web medium from the transport path into an initial curve (IC) in the upper zone (30A) in the buffer region. The initial curve is then expanded away from the pressing device in the second position downwards into the buffer region for forming a blouse in a lower zone (30B)of the buffer region.

Description

FIELD OF THE INVENTION

The present invention generally pertains to a printing system and a method for forming a blouse in a web medium.

BACKGROUND ART

Printing system for web-based media, such as roll-to-roll printers, are known to comprise a buffer region or blouse forming region between the print surface below the image forming unit and the take-up roller for winding the printed web medium onto a roll. The blouse is a free hanging U-shaped curve in the web medium between the print surface and the take-up roller. This blouse provides a buffer decoupling the section of the medium below the image forming unit from the pulling force from the driven take-roller. Thereby, the medium is not displaced while being printed on. The blouse is generally formed under the influence of gravity by basically allowing a section of the web medium to hang free in the buffer region. Upon feeding additional web medium into the buffer region, while temporarily reducing the amount of medium leaving the buffer region, the blouse is formed to the desired size. This, however, requires sufficient flexibility of the web medium, such that it deforms into the desired blouse shape under the influence of gravity. Certain media types possess a stiffness too great to allow such deformation. These stiff media do in a limited manner curve downwards into the buffer region, but due to their large stiffness, the upstream section of the web medium below the image forming unit is consequently leveraged upward (see Fig. 3). A disadvantage of the known web printing system is their inability for forming a blouse in stiff media, limiting the media versatility of these systems.

SUMMARY OF THE INVENTION

It is an object of the present invention, to provide a compact web printing system with a wide media versatility.
In a first aspect of the present invention, a printing system for web media according to claim 1 is provided. The printing system comprises:

a transport path for transporting a web medium from a take-out roller to a take-up roller;
a buffer region positioned below the transport path for allowing the web medium to curve away from the transport path in the downward direction;
a pressing device moveable along a guide between:
- a first position positioned above the transport path; and
- second position positioned below the transport path in an upper zone of the buffer region, such that movement of the pressing device from the first position to the second position presses the web medium from the transport path into an initial curve in the upper zone in the buffer region;
- a locking device for holding the pressing device at the second position on the guide;
- a transport system for moving the medium along the transport path, such that the initial curve of the medium at the pressing device in the second position is expanded away from the pressing device in the second position downwards into the buffer region for forming a blouse section in the web medium in a lower zone of the buffer region.

The printing system comprises a buffer region suitable for media of "average" stiffness. The printing system is suitable for stiffer media by application of the pressing device. A stiff medium may be positioned over the buffer region in a commonly applied manner for media of "average" stiffness. The pressing device, for example a page-wide roller, is then lowered from the first position above the web medium onto the web medium. Thereby, the stiff web medium is deformed and pressed into the buffer zone. The pressing device moves downward until it engages the locking device on the guide, which prevents the pressing device from moving beyond the second position. In this manner, an initial blouse-shaped curve is formed in the stiff web medium. The transport system is then controlled to feed a desired or predefined amount of the stiff medium into the buffer region. The transport system preferably further limits or reduces the transport of the stiff web medium out of the buffer region. Thereby, the initial curve expands away from the pressing device in the second position. As such, the initial curve is evolved into a blouse, which hangs freely in the buffer region without contacting the pressing device. It is the insight of the inventors that the initial curve formed by the pressing device provides sufficient deformation of the web medium to expand into a blouse without affecting the position of the medium upstream of the buffer region. This provides an adequate decoupling of medium being printed on from the forces of the take-up roller. The pressing device allows the buffer region to be positioned near the print surface, resulting in a compact printing system. Additionally, the pressing device increases the media versatility, as it allows for printing on stiffer media. Thereby, the object of the present invention is achieved.
In an embodiment, the printing system according to the present invention further comprises a controller configured for:

moving the pressing device from the first position to the second position, such that the pressing device presses the web medium over the buffer region into an initial curve in the buffer region; and
controlling the transport system while holding the pressing device at or above the second position to expand the initial curve further into the buffer region.

In another embodiment, the printing system according to the present invention further comprises a controller configured for:

in a first print mode, with the pressing device in the first position, forming a blouse in the web medium by feeding web medium from the take-out roller into the buffer region;
in a second print mode, with the pressing device in the second position, expanding the initial curve into a blouse by feeding web medium from the take-out roller into the buffer region; and
in a third print mode, with the pressing device in the third position, transporting a web medium under tension from the take-out roller to the take-up roller.

a first class of sufficient flexibility under the influence of gravity so that blouse formation occurs substantially unaided when suspending;
a second class so rigid that the web medium does not sufficiently curve into the buffer region under the influence of gravity; and
a third class of media so easily deformable these require a constant tension in the transport direction to prevent these from wrinkling during transport.

In an embodiment, the controller is further configured for:

receiving a print job comprising media type information;
determining whether the medium indicated in the media type information is unsuited for blouse formation in the first print mode; and
selecting the second print mode for media types determined to be unsuited for blouse formation in the first print mode.

In an embodiment, the pressing device is further moveable to a third position positioned in the lower zone in the buffer region below the second position. Preferably, the printing system comprises an actuatable transport roll upstream of the print surface for controllably pushing the web medium over the print surface. Certain flexible or weak media type do not allow for such "pushing" transport. The weak media are generally transported under continuous tension from the take-out roller to the take-up roller, such that these media are pulled through the printing system. By positioning the pressing device in the third position preferably near the bottom of the buffer region, the pressing device is configured as a tensioning device for forming a U-shaped curve in the weak medium. Preferably, the guide is configured for free vertical movement of the roller in the third position during printing. The pressing device then under the influence of gravity provides a tensioning force on the weak medium. No locking device is then required at the third position. By allowing the guide to extend over the height of the buffer region, the media versatility can thus be increased further.
In a further embodiment, the guide comprises translating means for allowing the pressing device to translate substantially unimpeded or freely along the guide under the influence of gravity. This allows the pressing device to move downwards under the influence of gravity. No additional actuator is then required, reducing the costs of the printing system. The translating means may e.g. comprise sliders or vertically extending racks, wherein the roller comprises a pair of corresponding pinions. Preferably, the translating means are configured for maintaining the pressing device in a horizontal orientation during its vertical movement. It will be appreciated that dampening means may be provided to reduce the speed or acceleration of the unimpeded or free descend of the pressing device for reasons of safety.
In another embodiment, the locking device, when engaged, limits the movement of the pressing device along the guide between the first and second position. The locking device is preferably configured to rotatably secure the pressing roller in the second position. When the locking device is in disengagement or not activated, the pressing device may freely travel over the full length of the guide, for example to the third position for the tensioning of weak media.
In an embodiment, the pressing device is a roller provided between a pair of a parallel guides for directing the roller from the first position to the second and/or third position.
In another embodiment, the locking device is configured to prevent the pressing device from descending below the second position under the influence of gravity. An additional holding device may be provided at the first position to locking device the pressing device above the transport path. Preferably, the third position does not comprise a holding device such that the pressing device due to gravity exerts a tensioning force on the web medium. Preferably, the guide is configured such that the pressing device moves is substantially free along the guide with the exception of the second position when the locking device is engaged.
In another embodiment, the printing system according to the present invention further comprises a controller configured for:

in a first print mode, preferably with the pressing device in the first position or without a pressing device, forming a blouse in the web medium by feeding web medium from the take-out roller into the buffer region;
in a second print mode, with the pressing device in the second position, expanding the initial curve into a blouse by feeding web medium from the take-out roller into the buffer region; and
in a third print mode, with the pressing device in the third position, transporting a web medium under tension from the take-out roller to the take-up roller.

In a further embodiment, the printing system according to the present invention further comprises a locking sensor for detecting engagement of the locking device, wherein the controller is further configured for:

in the second print mode, to prevent printing when the sensor detects disengagement of the locking device; and
in the third print mode, to prevent printing when the sensor detects engagement of the locking device.

The locking sensor detects whether the locking device is engaged with the guide by detecting whether or not the locking device is in its locking position on the guide. In the locking position, the locking device prevents the pressing roller from descending below the second position. The sensor provides information regarding the state of the locking device, such that, in the second print mode wherein the presence of the pressing roller is required, the controller prevents printing from commencing when the locking device is detected to be absent from its locking position. In the third print mode, the pressing roller is required to descend to the third position. Thus, the controller starts the print job, when the sensor detects that the locking device is not present at its locking position, such that the pressing device may travel unimpeded to the third position.
In a further embodiment, the printing system according to the present invention further comprises a transport surface plate moveable between:

a closed position, wherein the transport surface plate extends over the buffer region forming the transport path for transporting the web medium over the buffer region; and
an open position, wherein the buffer region is accessible from above.

In a further aspect, the present invention provides a method for forming a blouse in a web medium in a printing system according to claim 11. Said method comprises the steps of:

positioning the web medium over a buffer region;
lowering a pressing device onto the web medium positioned over the buffer region to a second position in an upper zone of the buffer region, thereby forming an initial curve in the web medium in the buffer region;
feeding web medium into the buffer region, thereby expanding the initial curve into a blouse in the buffer region.

In an embodiment, the method according to the present invention further comprises the step of engaging a locking device at the second position to prevent the pressing device from moving the second position. The locking device may be a clamp or insert on which the pressing roller is supported in the second position. The locking device is positioned at its locking position on the guide. In the locking position, the locking device prevents the pressing device from descending below the second position. The blouse is then formed below the pressing device in the second position.
In another embodiment, the pressing device is a roller and the method according to the present invention further comprises the step of rotatably fixing the roller at the second position. The locking device in the locking position is configured for rotation of the pressing roller around its longitudinal rotation axis at the second position.
In a further embodiment, the method according to the present invention further comprises the steps of:

detecting the fixation of the roller at the second position; and
printing when the fixation of the roller at the second position has been detected.

In an embodiment, the method according to the present invention further comprises the step of moving a buffer plate from a closed position over the buffer region to an open position, wherein the buffer region is accessible to the pressing device and the web medium.
In another embodiment, the method according to the present invention comprises the steps of:

receiving a print job comprising media type information;
determining whether the medium indicated by the media type information is unsuited for blouse formation in the first print mode; and
selecting the second print mode for media types determined to be unsuited for blouse formation in the first print mode. Preferably, the controller is further configured for:
- comparing the media type information to a media type look-up table with therein media types requiring operation in the second print mode.

Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating embodiments of the invention, are given by way of illustration only, since various changes and modifications within the scope of the invention will become apparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying schematical drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:

Fig. 1A shows a perspective schematic view of a printing according to the present invention;
Fig. 1B shows the image forming unit of the printing system in Fig. 1A;
Fig. 2A-B illustrate in a schematic side view the formation of blouse for media of "average" stiffness in the printing system of Fig. 1A;
Fig. 3 illustrates in a schematic side view the issues arising when applying the method in Figs. 2A-B to stiff or rigid media;
Fig. 4A-D illustrates in a schematic side view the different steps of forming a blouse in a printing system according to the present invention;
Fig. 5 illustrates in a schematic side view the third printing mode for weak media in a printing system according to the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

The present invention will now be described with reference to the accompanying drawings, wherein the same reference numerals have been used to identify the same or similar elements throughout the several views.
Fig. 1A shows an image forming apparatus 1, wherein printing is achieved using a wide format inkjet printer. The wide-format image forming apparatus 1 comprises a housing 2, wherein the printing assembly, for example the inkjet printing assembly shown in Fig. 1B is placed. The image forming apparatus 1 also comprises a storage means for storing image receiving member 3, 4, a delivery station to collect the image receiving member 3, 4 after printing and storage means 5 for marking material. In Fig. 1A, the delivery station is embodied as a delivery tray 6. Optionally, the delivery station may comprise processing means for processing the image receiving member 3, 4 after printing, e.g. a folder or a puncher. The wide-format image forming apparatus 1 furthermore comprises means for receiving print jobs and optionally means for manipulating print jobs. These means may include a user interface unit 8 and/or a control unit 7, for example a computer.
Images are printed on a image receiving member, for example paper, supplied by a roll 3, 4. The roll 3 is supported on the roll support R1, while the roll 4 is supported on the roll support R2. Alternatively, cut sheet image receiving members may be used instead of rolls 3, 4 of image receiving member. Printed sheets of the image receiving member, cut off from the roll 3, 4, are deposited in the delivery tray 6.
Each one of the marking materials for use in the printing assembly are stored in four containers 5 arranged in fluid connection with the respective print heads for supplying marking material to said print heads.
The local user interface unit 8 is integrated to the print engine and may comprise a display unit and a control panel. Alternatively, the control panel may be integrated in the display unit, for example in the form of a touch-screen control panel. The local user interface unit 8 is connected to a control unit 7 placed inside the printing apparatus 1. The control unit 7, for example a computer, comprises a processor adapted to issue commands to the print engine, for example for controlling the print process. The image forming apparatus 1 may optionally be connected to a network N. The connection to the network N is diagrammatically shown in the form of a cable 9, but nevertheless, the connection could be wireless. The image forming apparatus 1 may receive printing jobs via the network. Further, optionally, the controller of the printer may be provided with a USB port, so printing jobs may be sent to the printer via this USB port.
Fig. 1B shows an ink jet printing assembly 10. The ink jet printing assembly 10 comprises supporting means for supporting an image receiving member 3. The supporting means 11 are shown in Fig. 1B as a platen 11, but alternatively, the supporting means 11 may be a flat surface. The platen 11, as depicted in Fig. 1B, is a rotatable drum 11, which is rotatable about its axis as indicated by arrow A. The supporting means 11 may be optionally provided with suction holes for holding the image receiving member 3 in a fixed position with respect to the supporting means 11. The ink jet printing assembly 10 comprises print heads 12a - 12d, mounted on a scanning print carriage 13. The scanning print carriage 13 is guided by suitable guiding means 14, 15 to move in reciprocation in the main scanning direction B. Each print head 12a - 12d comprises an orifice surface 16, which orifice surface 16 is provided with at least one orifice 17. The print heads 12a - 12d are configured to eject droplets of marking material onto the image receiving member 3. The platen 11, the carriage 13 and the print heads 12a - 12d are controlled by suitable controlling means 18a, 18b and 18c, respectively.
The image receiving member 3 may be a medium in web or in sheet form and may be composed of e.g. paper, cardboard, label stock, coated paper, plastic or textile. Alternatively, the image receiving member 3 may also be an intermediate member, endless or not. Examples of endless members, which may be moved cyclically, are a belt or a drum. The image receiving member 3 is moved in the sub-scanning direction A by the platen 11 along four print heads 12a - 12d provided with a fluid marking material.
A scanning print carriage 13 carries the four print heads 12a - 12d and may be moved in reciprocation in the main scanning direction B parallel to the platen 11, such as to enable scanning of the image receiving member 3 in the main scanning direction B. Only four print heads 12a - 12d are depicted for demonstrating the invention. In practice an arbitrary number of print heads may be employed. In any case, at least one print head 12a - 12d per color of marking material is placed on the scanning print carriage 13. For example, for a black-and-white printer, at least one print head 12a - 12d, usually containing black marking material is present. Alternatively, a black-and-white printer may comprise a white marking material, which is to be applied on a black image-receiving member 3. For a full-color printer, containing multiple colors, at least one print head 12a - 12d for each of the colors, usually black, cyan, magenta and yellow is present. Often, in a full-color printer, black marking material is used more frequently in comparison to differently colored marking material. Therefore, more print heads 12a - 12d containing black marking material may be provided on the scanning print carriage 13 compared to print heads 12a - 12d containing marking material in any of the other colors. Alternatively, the print head 12a - 12d containing black marking material may be larger than any of the print heads 12a - 12d, containing a differently colored marking material.
The carriage 13 is guided by guiding means 14, 15. These guiding means 14, 15 may be rods as depicted in Fig. 1B. The rods may be driven by suitable driving means (not shown). Alternatively, the carriage 13 may be guided by other guiding means, such as an arm being able to move the carriage 13. Another alternative is to move the image receiving material 3 in the main scanning direction B.
Each print head 12a - 12d comprises an orifice surface 16 having at least one orifice 17, in fluid communication with a pressure chamber containing fluid marking material provided in the print head 12a - 12d. On the orifice surface 16, a number of orifices 17 is arranged in a single linear array parallel to the sub-scanning direction A. Eight orifices 17 per print head 12a - 12d are depicted in Fig. 1B, however obviously in a practical embodiment several hundreds of orifices 17 may be provided per print head 12a - 12d, optionally arranged in multiple arrays. As depicted in Fig. 1B, the respective print heads 12a - 12d are placed parallel to each other such that corresponding orifices 17 of the respective print heads 12a - 12d are positioned in-line in the main scanning direction B. This means that a line of image dots in the main scanning direction B may be formed by selectively activating up to four orifices 17, each of them being part of a different print head 12a - 12d. This parallel positioning of the print heads 12a - 12d with corresponding in-line placement of the orifices 17 is advantageous to increase productivity and/or improve print quality. Alternatively multiple print heads 12a - 12d may be placed on the print carriage adjacent to each other such that the orifices 17 of the respective print heads 12a - 12d are positioned in a staggered configuration instead of in-line. For instance, this may be done to increase the print resolution or to enlarge the effective print area, which may be addressed in a single scan in the main scanning direction. The image dots are formed by ejecting droplets of marking material from the orifices 17.
Upon ejection of the marking material, some marking material may be spilled and stay on the orifice surface 16 of the print head 12a - 12d. The ink present on the orifice surface 16, may negatively influence the ejection of droplets and the placement of these droplets on the image receiving member 3. Therefore, it may be advantageous to remove excess of ink from the orifice surface 16. The excess of ink may be removed for example by wiping with a wiper and/or by application of a suitable anti-wetting property of the surface, e.g. provided by a coating.
Fig. 2A shows a schematic side view of a printing system 1 according to the present invention. Web medium 3 is fed from a take-out roller R1 or supply roller R1 to a transport roller R5. The transport roller R5 comprises an actuator for accurate moving the transport roller R5 to push the web medium 3 over the print surface 11. Above the print surface 11 the image forming unit 11 is provided. Downstream of the print surface 11, the web medium 3 moves over the buffer region 30 via a transport surface plate 20. The transport surface plate 20 is in its closed position, thereby defining the transport path P. The buffer region 30 is positioned between an upstream support element 32 and a downstream support element R4. The upstream support element 32 in Fig. 2A is a static support surface, while the downstream support element R4 is illustrated as a roller R4. Other support elements may be applied within the scope of the present invention. Downstream of the downstream support element R4, the web medium 3 is wound onto the take-up roller R3. The take-up roller R3 is a winder R3 provided with its own driving means.
For media 3 of "average" stiffness, the blouse formation is shown in Fig. 2B. Media of "average" stiffness are defined as media 3 which are suited for blouse formation under the influence of gravity alone. In a first step the web medium 3 is positioned over the buffer region 30 on the transport surface plate 20 in the closed position, as shown in Fig. 2A. In a subsequent step, the transport surface plate 20 is pivoted in direction of arrow A to its open position, thereby opening the buffer region 30 below the web medium 3. Web medium 3 is in a next step fed, by actuation of the transport roller R5, into the buffer region 30. Downstream of the buffer region 30, transport of the web medium 3 is halted or slowed, for example by reducing the speed of the take-roller R3 or by clamping the web medium 3 onto the downstream support element R4 by means of clamp 50. The web medium 3 thereby sags under the influence of gravity in the downward vertical direction V. Thereby a blouse B is formed. The blouse B is suspended on the upstream and downstream support elements 32, R4 in a free hanging manner. The U-shaped curve at the bottom of the blouse B provides decoupling of the pulling force from the take-up roller R3 from the section of the web medium 3 on the print surface 11.
When applying the blouse formation method of Figs. 2A-B to stiff media, the issues shown in Fig. 3 arise. The stiff web medium 3 does partially sag into the buffer region 30 when the transport surface plate 20 is opened, but due to its large stiffness, the section of the stiff web medium 3 over the print surface 11 is raised against the image forming unit 10. The large page width of the web medium 3 generally prevents the operator from manually interfering without folding or otherwise damaging the web medium 3. Stiff media 3 are herein defined as media unsuited for blouse formation by means of gravity alone.
To solve the issues shown in Fig. 3, the present invention provides a pressing device 40 shown in Fig. 4A. The pressing device 40 is in the form of a roller 40 or otherwise suitable web media guidance means. The pressing device 40 is moveable between a first position 40A above the stiff web medium 3 on the transport path P formed by the transport surface plate 20 in the closed position. In the first step, the stiff web medium 3 is fed in a similar as described for Fig. 2A-B. After attachment to the take-up roller R3, the transport surface plate 20 is opened. In consequence the stiff web medium 3 over the buffer region 30 becomes free hanging over the buffer region 30. In a subsequent step shown in Figs 3B-C, the pressing device 40 is moved from the first position 40A above the web medium 3 into the buffer region 30. Thereby, the stiff web medium 3 is pressed into the buffer region 30. The page-wide pressing device 40 descends along a guide (shown as 44 in Fig. 5) to the second position 40B. The second position 40B is positioned below the first position 40A, such that the pressing device 40 may descend by gravity. The second position 40B is further positioned below the transport path P formed by the transport surface plate 20 in the closed position. The second position 40B is located in an upper zone (30A in Fig. 4D), which upper zone 30A is formed by the top section or region of the buffer region 30. Thereby, the second position 40B is near the transport path P.
The locking device 42 defines the second position 40B. When positioned in its locking position on the guide 44, the locking device 42 prevents the pressing device 40 from descending lower than the second position 40B. In consequence, in the step of moving the pressing device 40 to the second position 40B, an initial curve IC is formed in the stiff web medium 3. The initial curve IC extends into buffer region 30, but is limited to the upper zone 30A.
In a following step, shown in Fig. 4D, stiff web medium 3 is fed into the buffer region 30 in a manner similar to Figs. 2A-B. The initial curve IC provides sufficient deformation of the web medium 3 in the buffer region 30, such that the initial curve IC expands into a blouse B in lower zone 30B of the buffer region 30. Thereby, due to the depth of the U-shaped initial curve IC, the position of the web medium 3 on the print surface 11 is not affected. The pressing device 40 remains in the second position 40B (or may be removed), while the initial curve IC expands away from the second position 40B in de downward direction. Thereby, a suitable blouse B may be formed in stiff web media 3. As shown in Fig. 4D, the lower zone 30B forms the majority of the buffer region 30. The upper zone 30A is preferably positioned in the upper half, third, or quarter of the buffer region 30.
The controller 7 is configured for printing in at least three print modes, corresponding respectively to the printing of "average", stiff, and weak media. In the first or "average" media mode, the pressing device is not applied and the controller 7 operates the transport surface plate 20, following by actuating the transport roller R3 to form the blouse B. In the second or stiff media mode, the controller 7 is configured to actuate the transport roller R5 when the pressing device 40 is in the second position 40B for forming the blouse. In the third or weak media mode, the controller 7 is configured to actuate the transport roller R5 when the pressing device 40 is in the third position 40C for tensioning the weak web medium 3.
The locking device 32 comprises a locking sensor for detecting the presence of the locking device 32 in the locking position, wherein the locking device 32 prevents the pressing roller 40 from descending below the second position 40B. The controller 7 is configured to receive locking information from the locking sensor. In the second print mode for stiff media, the controller 7 is programmed to prevent printing when the locking sensor detects that the locking device 42 is not in its locking position. In the third print mode for weak media, the controller 7 is programmed to prevent printing when the locking sensor detects that the locking device 42 is in its locking position.
Fig. 5 illustrates the printing system 1 according to the present invention configured for printing weak web media 3. Such weak or flexible web media 3 deform or wrinkle when being pushed over the print surface 11 by the transport roller R5. As such, these weak media 3 require tensioning for transport. Thereto, the pressing device 40 is suspended on the weak web medium 3 at the third position 40C. The guide 44 provides free movement in the vertical direction V of the pressing device 40 at the third position 40C, such that due to gravity the pressing device 40 exerts a tensioning force on the weak web medium 3. The third position 40C is positioned in the lower zone 30B of the buffer region 30 below the second position 40B. The first, second, and/or third positions 40A-C are aligned along the guide 44, preferably in the substantially vertical direction V. In this manner, the pressing device 40 according to the present invention enables printing of weak, "average", and stiff web media 3 on a printing system 1.
It will be appreciated that herein above, below, upper, lower, etc. are defined with respect to the vertical direction V.
Detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which can be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure. In particular, features presented and described in separate dependent claims may be applied in combination and any advantageous combination of such claims are herewith disclosed.
Further, it is contemplated that structural elements may be generated by application of three-dimensional (3D) printing techniques. Therefore, any reference to a structural element is intended to encompass any computer executable instructions that instruct a computer to generate such a structural element by three-dimensional printing techniques or similar computer controlled manufacturing techniques. Furthermore, such a reference to a structural element encompasses a computer readable medium carrying such computer executable instructions.
Further, the terms and phrases used herein are not intended to be limiting; but rather, to provide an understandable description of the invention. The terms "a" or "an", as used herein, are defined as one or more than one. The term plurality, as used herein, is defined as two or more than two. The term another, as used herein, is defined as at least a second or more. The terms including and/or having, as used herein, are defined as comprising (i.e., open language). The term coupled, as used herein, is defined as connected, although not necessarily directly.
The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.

Claims

Printing system (1) for web media, comprising:
- a transport path (P) for transporting a web medium (3) from a take-out roller (R1) to a take-up roller (R3);

- a buffer region (30) positioned below the transport path for allowing the web medium to curve away from the transport path in the downward direction (V);

- a pressing device (40) moveable along a guide (44) between:
- a first position (40A) positioned above the transport path; and

- a second position (40B) positioned below the transport path in an upper zone (30A) of the buffer region, such that movement of the pressing device from the first position to the second position presses the web medium from the transport path into an initial curve (IC) in the upper zone in the buffer region;

- a locking device (42) for holding the pressing device at the second position on the guide;

- a transport system (R5) for moving the medium along the transport path, such that the initial curve of the medium at the pressing device in the second position is expanded away from the pressing device in the second position downwards into the buffer region for forming a blouse section (B) in the web medium in a lower zone (30B) of the buffer region.
The printing system (1) according to claim 1, further comprising a controller configured for:
- in a first print mode, with the pressing device (40) in the first position (40A), forming a blouse in the web medium by feeding web medium from the take-out roller into the buffer region;

- in a second print mode, with the pressing device in the second position (40B), expanding the initial curve into a blouse by feeding web medium from the take-out roller into the buffer region (B); and

- in a third print mode, with the pressing device in the third position, transporting a web medium under tension from the take-out roller to the take-up roller.
The printing system (1) according to claim 1 or 2, further comprising a controller configured for:
- moving the pressing device (40) from the first position (40A) to the second position (40B), such that the pressing device (40) presses the web medium over the buffer region (B) into an initial curve in the buffer region (B); and

- controlling the transport system while holding the pressing device (40) at or above the second position to expand the initial curve further into the buffer region.
The printing system (1) according to claim 2 or 3, wherein in the controller (7) is further configured for:
- receiving a print job comprising media type information;

- determining whether the medium indicated in the media type information is unsuited for blouse formation in the first print mode; and

- selecting the second print mode for media types determined to be unsuited for blouse formation in the first print mode.
The printing system (1) according to claim 4, wherein in the controller (7) is further configured for:
- comparing the media type information to a media type look-up table with therein media types requiring operation in the second print mode.
The printing system (1) according to any of the previous claims, wherein the pressing device (40) is further moveable to:
- a third position (40C) positioned in the lower zone in the buffer region below the second position.
Printing system for web media according to claim 6, wherein the guide comprises translating means for allowing the pressing device to translate substantially unimpeded along the guide under the influence of gravity.
Printing system according to any of the previous claims, wherein the locking device, when engaged, limits the movement of the pressing device along the guide between the first and second position.
Printing system according to any of the previous claims, wherein the pressing device is a roller provided between a pair of a parallel guides for directing the roller from the first position to the second and/or third position.
Printing system according to claim 9, wherein the pair of a parallel guides comprise vertically extending racks and the roller a pair of corresponding pinions.
Printing system according to any of the previous claims, further comprising a locking sensor for detecting engagement of the locking device, wherein the controller is further configured for:
- in the second print mode, to prevent printing when the sensor detects disengagement of the locking device; and

- in the third print mode, to prevent printing when the sensor detects engagement of the locking device.
Printing system according to 9, 10, or 11, wherein the pair of guides are configured for free vertical movement of the roller in the third position during printing.
Printing system according to any of the previous claims, further comprising a transport surface plate (20) moveable between:
- a closed position, wherein the transport surface plate extends over the buffer region forming the transport path for transporting the web medium over the buffer region; and

- an open position, wherein the buffer region is accessible from above.
Method forming a blouse (B) in a web medium (3) in a printing system (1), comprising the steps of:
- positioning the web medium over a buffer region (30);

- lowering a pressing device (40) onto the web medium positioned over the buffer region to a second position (40B) in an upper zone (30A) of the buffer region, thereby forming an initial curve (IC) in the web medium in the buffer region;

- feeding web medium into the buffer region, thereby expanding the initial curve into a blouse in the buffer region.
Method according to claim 14, further comprising the step of engaging a locking device (42) at the second position to prevent the pressing device from moving the second position.