EP4606750A1

EP4606750A1 - A method for loading, de-wrinkling, and aligning web media in a printer

Info

Publication number: EP4606750A1
Application number: EP24186531.0A
Authority: EP
Inventors: Marcus H.G.W. Hees
Original assignee: Canon Inc
Current assignee: Canon Inc
Priority date: 2024-02-20
Filing date: 2024-07-04
Publication date: 2025-08-27

Abstract

An efficient method of loading and aligning a print medium from an input roller onto a transport belt of a printer is provided. The method comprises the steps of:- positioning at least a leading portion of the print medium (16) on the belt (4) over a suction chamber assembly (5) extending along the belt (4);- applying a first negative pressure to the suction chamber assembly (5) to draw the print medium (16) towards the belt (4);- securing an upstream portion of the print medium (16), while the first negative pressure is being applied and the belt (4) is moved with respect to the leading portion of the print medium (16).

Description

BACKGROUND OF THE INVENTION

1. Field of the invention

The invention relates to a method of loading a print medium onto a transport belt of a printer and to printer configured to perform said method.

2. Description of Background Art

Roll printers generally comprise an input roller from which a print medium in the form of a web is unwound and transport along a printhead assembly for printing one or more images on the print medium. Downstream of the printhead assembly, the print medium may be re-wound onto an output roller or processed into sheets, e.g. by cutting the web. Opposite the printhead assembly the print medium is supported on a medium support surface. For certain printers, the medium support surface is formed by an endless, air permeable transport belt which extends over a suction chamber assembly. By applying a sufficiently large, negative pressure to the suction chamber assembly, the print medium may be held against the belt, so that it can be transported by moving the belt. Loading a new print medium often involves an operator manually positioning at least a leading portion of the print medium on the belt over the suction chamber assembly extending along the belt. This allows for applying a first negative pressure to the suction chamber assembly to draw the print medium towards the belt. Therein, the operator commonly has to align the leading edge of the print medium with the axis of the output roller and/or drive wrinkles out of the print medium, so that it is suitably aligned and/or flattened for printing thereon.

SUMMARY OF THE INVENTION

It is an object of the invention to provide to provide a productive method of loading a print medium onto a transport belt of a printer.
In accordance with the present invention, a method of loading a print medium according to claim 1 and a printer according to claim 10 are provided.
Such a printer may comprise a printing assembly configured to print an image on the print medium, a transport belt configured to transport the print medium to the printing assembly in a transporting direction and a suction chamber assembly configured to suck the print medium on the transport belt.
The method comprises the step of applying a first negative pressure to the suction chamber assembly, while a leading portion of the print medium is positioned on the transport belt to draw the leading portion towards the transport belt.
The method is characterized by the step of securing an upstream portion of the print medium in the transporting direction, while the first negative pressure is being applied and the transport belt is moved with respect to the leading portion of the print medium in the transporting direction.
The leading portion of the print medium is positioned on the belt, so that it extends over the suction chamber assembly. A negative pressure is applied in the suction chamber, so that the print medium is drawn towards the belt. A trailing portion of the print medium following the leading portion is securely held in place, preventing the leading portion from substantially moving forward in a transport direction of the belt. In consequence, when the belt is moved, the belt slips or slides past the leading portion of the print medium. It will be appreciated that the first negative pressure is selected to be within a range to allow such slipping. The first negative pressure draws the leading portion against the belt. Wrinkles in the leading portion are driven towards the leading edge of the print medium by the sliding movement of the belt. Wrinkles can so be 'ironed' out of the leading portion. Due to this relative slipping movement, the leading portion becomes better flattened against the belt. Additionally, the leading portion is aligned in the transport direction of the belt due to the motion of the belt in said direction. In consequence, the leading edge of the print medium is aligned perpendicular to the transport direction and thus parallel to the output roller. This allows the operator to effectively secure the leading edge to the output roller without the need for manual aligning and/or de-wrinkling operations. Thereby the object of the present invention has been achieved.
More specific optional features of the invention are indicated in the dependent claims.
In an embodiment, the moving belt slips along the upstream portion of the print medium. The print medium is held securely at a portion somewhere before or at the upstream side of the suction chamber assembly. The leading portion is thus substantially unable to move further in the transport direction of the belt. When the belt is driven, the belt moves with respect to the leading portion by slipping past it. The first negative pressure draws the leading portion against the belt, but this normal force is sufficiently small to allow the belt to slip along the respective surface of the print medium without damaging it. Slipping herein is preferably defined as a relative motion between the belt and the leading portion, when these are in constant contact with one another, specifically when being forced against one another by means of the first pressure. Slipping may include sliding, shifting, gliding, slithering, skidding, etc. It will be appreciated that during the slipping the leading edge of the print medium may move slight forward in the transport direction, as the wrinkles are driven from the print medium.
In an embodiment, the first negative pressure has been set and/or selected, such that the belt and print medium are drawn towards one another while allowing these to slip along one another. The first negative pressure has been selected, so that the driving force the belt exerts on the leading portion exceeds the maximum static friction force. The maximum static friction force is proportional to the normal force applied by means of the first negative pressure, so said force can be chosen to be low, to allow the belt to slip without the risk of tearing the print medium. It will be appreciated that in practice the first negative pressure is relatively small, i.e. relatively near or close atmospheric pressure, and that it may be scaled for more resilient print media.
In an embodiment, the step of applying the first negative pressure and moving the belt is performed at least until a leading edge of the print medium is substantially aligned with respect to a lateral direction of the belt, preferably parallel thereto, and/or wrinkles in the print medium have been substantially driven out of the print medium in a transport direction of the belt. The movement of the belt in its transport direction over time forces the leading portion to be become aligned in said direction. Wrinkles are move through the leading portion to and out of the leading edge, so that wrinkles are removed. Dependent on the type of print medium, this period may vary.
In an embodiment, the method further comprises the steps of releasing the upstream portion of the print medium and moving the print medium by means of the belt in a transport direction of the belt. After alignment and/or de-wrinkling, the print medium is to be moved by the belt to allow printing on it. Thereto, the leading portion is held in place against the belt when the belt is driven. Thereby, the aligned leading edge can be brought to the output roller, where it can be secured to allow for roll-to-roll printing. In another embodiment, the method further comprises attaching the aligned leading edge to the output roller, followed by winding the print medium on the output roller.
In an embodiment, the method further comprises:

applying a second negative pressure to the suction chamber assembly, which second negative pressure is more negative than the first negative pressure;
holding the print medium securely on the belt by means of the second negative pressure, so that the print medium moves with the belt. The second negative pressure is further removed from atmospheric pressure than the first negative pressure, so that the normal force on the print medium when applying the second negative pressure is relatively greater. The second negative pressure results in a relatively large frictional force between the belt and the print medium that forces the print medium to move with the belt, i.e. substantially without slipping. It will be appreciated that the first and second pressures may in one example be applied via different suction chambers, so that the first and second pressures may be applied simultaneously, e.g. during printing. In another example, the first and second pressures may be applied via the same suction chamber by changing the pressure in said chamber during the respective, different steps of the method.

In an embodiment, the print medium is supplied from an input roller and the step of securing the print medium comprises preventing rotation of the input roller and the step of releasing comprises allowing for rotation of the input roller. Rotation of the input roller is prevented during the de-wrinkling and/or alignment of the leading portion due to slipping of the belt. The input roller is made rotatable when feeding print medium onto the belt to bring the leading edge to the output roller and/or during printing when the print medium moves with the belt without slipping. The securing may be achieved by controlling a motor for the rotating the input roller, wherein when securing the motor locks or fixes the input roller, or by a separate locking mechanism to releasably fix the input roller.
In an embodiment, the step of moving the print medium comprising unwinding the print medium from the input roller. When the print medium is locally secured, no further print medium is unwound from the input roller. After de-wrinkling and/or alignment, the leading edge is to be brought to the output. Thereto, the input roller is rotated, so that print medium is unspooled from the input roller. This allow the print medium to move with the belt.
The present invention further relates to a printer comprising an endless, air permeable transport belt extending along a suction chamber assembly and a controller configured for performing the method according to any of the previous claims. The suction chamber assembly is connected to a suction source. The controller can control the suction chamber assembly to selectively apply the first and second pressures. This may be achieved by different suction chambers, each arranged to apply one of the first and second pressures. Alternatively or additionally, the pressure within a single pressure chamber may be varied between the first and second pressures. The controller further controls a securing mechanism for locally securing a portion of the print medium upstream of the belt. Such a securing mechanism may be comprised in or as a motor for rotating the input roller. Alternatively, a separate locking mechanism is provided which can prevent rotation of the input roller or directly engage and hold the print medium.
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 preferred embodiments of the present invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the present 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 herein below and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:

Fig. 1 is a schematic, perspective view of a printing system configured in a mode for printing on rigid sheets of print media;
Fig. 2 is a schematic, perspective view of a printing system configured in a mode for printing on web media spooling from one roller to the other;
Fig. 3 is a schematic, cross-sectional view of the printer in Fig. 2 during the step of bringing a leading portion of the print medium onto the belt;
Fig. 4 is a schematic, cross-sectional view of the printer in Fig. 2 during a step of applying a second, negative pressure to the leading portion, so that it can be transported by means of the belt;
Fig. 5 is a schematic, cross-sectional view of the printer in Fig. 2 during a step of applying a first, negative pressure smaller than the second to the leading portion, while securing an upstream portion of the print medium and driving the belt;
Fig. 6 is a schematic, cross-sectional view of the printer in Fig. 2 wherein the leading portion has been de-wrinkled and aligned due to the actions shown in Fig. 5;
Fig. 7 is a schematic, cross-sectional view of the printer in Fig. 2 during a step of applying both the first and second, negative pressure to transport the leading edge to the output roller, so that the print medium can be spooled onto the output roller;
Fig. 8 is a schematic, top-down view of the printer in the situation shown in Fig. 4;
Fig. 9 is a schematic, top-down view of the printer in the situation shown in Fig. 5;
Fig. 10 is a schematic, top-down view of the printer in the situation shown in Fig. 6; and
Fig. 11 is a diagram illustrating the steps of a method of printing according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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.

Printing system

Fig. 1 shows a wide format inkjet printer 1. The wide-format printer 1 comprises an inkjet printing assembly 7 for printing on a print medium 15. The print medium 15 in Fig. 1 is a relatively rigid substrate, such as a panel. The print medium 15 is supplied from a media input unit 14, which may be configured for storing a plurality of such print media 15 and supplying these to the printer 1. The printer 1 comprises transport means for receiving and transporting the print medium 15 along the inkjet printing assembly 7. In Fig. 1, the transport means comprise an endless transport belt 4 supported on a plurality of support rollers 3A, 3B. At least one of the support rollers 3A, 3B is provided with driving means for moving the belt 4. Additionally, one or more one of the support rollers 3A, 3B may be configured to be moved and/or tilted to adjust and control the lateral position of the belt 4. The inkjet printing assembly 7 may be provided with a sensor 8, such as a CCD camera, to determine the relative position of belt 4 and/or the print medium 15. Data from said sensor 8 may be applied to control the position of the belt 4 and/or the print medium 15. The belt 4 is further provided with through-holes and a suction chamber assembly 5 in connection with a suction source (not shown), such that an negative pressure may be applied to the print medium 15 via the through-holes in the belt 4. The negative pressure adheres the print medium 15 flatly to the belt 4 and prevents displacement of the print medium 15 with respect to the belt 4. Due to this holding the belt 4 is able to transport the print medium 15. It will be appreciated that other suitable transport means, such as rollers, steppers, etc., may alternatively be applied. The print medium 15 may be transported stepwise and/or in continuous movement.
The inkjet printing assembly 7 is configured to translate along a first guide beam 6 in a scanning direction. The scanning direction is perpendicular to the direction in which the print medium is transported by the belt 4. The inkjet printing assembly 7 holds a plurality of print heads (not shown), which are configured to jet a plurality of different marking materials (different colors of ink, primers, coatings, etc.) on the print medium 15. Each marking material for use in the printing assembly 7 is stored in one of a plurality of containers arranged in fluid connection with the respective print heads for supplying marking material to said print heads to print an image on the print medium 15.
The ejection of the marking material from the print heads is performed in accordance with data provided in the respective print job. The timing by which the droplets of marking material are released from the print heads determines their position on the print medium 15. The timing may be adjusted based on the position of the inkjet printing assembly 7 along the first guide beam 6. The above mentioned sensor 8 may therein be applied to determine the relative position and/or velocity of the inkjet printing assembly 7 with respect to the print medium 15. Based upon data from the sensor 8, the release timing of the marking material may be adjusted.
Upon ejection of the marking material, some marking material may be spilled and stay on a nozzle surface of the print heads. The marking material present on the nozzle surface, may negatively influence the ejection of droplets and the placement of these droplets on the print medium 15. Therefore, it may be advantageous to remove excess of marking material from the nozzle surface. The excess of marking material 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.
The marking materials may require treatment to properly fixate them on the print medium. Thereto, a fixation unit 10 is provided downstream of the inkjet printing assembly 7. The fixation unit 10 may emit heat and/or radiation to facilitate the marking material fixation process. In the example of Fig. 1, the fixation unit 10 is a radiation emitter, which emits light of certain frequencies, which interacts with the marking materials, for example UV light in case of UV-curable inks. The fixation unit 10 in Fig. 1 is translatable along a second guide beam 9. Other fixation units 10, such as page-wide curing or drying stations may also be applied. Further, the inkjet printing assembly 7 may be provided with a further fixation unit on the same carriage which holds the print heads. This further fixation unit can be used to (partially) cure and/or harden the marking materials, independent of or interaction with the fixation unit 10.
After printing, and optionally fixation, the print medium 15 is transported to a receiving unit (not shown). The receiving unit may comprise a take-up roller for winding up the print medium 15, a receiving tray for supporting sheets of print medium 15, or a rigid media handler, similar to the media input unit 14. Optionally, the receiving unit may comprise processing means for processing the medium 8, 9 after printing, e.g. a posttreatment device such as a coater, a folder, a cutter, or a puncher.
The wide-format printer 1 furthermore comprises a user interface 11 for receiving print jobs and optionally for manipulating print jobs. The local user interface unit 11 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 11 is connected to a control unit 12 connected to the printer 1. The control unit 12, for example a computer, comprises a processor adapted to issue commands to the printer 1, for example for controlling the print process. The printer 1 may optionally be connected to a network. The connection to the network can be via cable or wireless. The printer 1 may receive printing jobs via the network. Further, optionally, the control unit 12 of the printer 1 may be provided with an input port, such as a USB port, so printing jobs may be sent to the printer 1 via this input port.

Hybrid printing system

The printer 1 in Fig. 1 is a so-called hybrid printer, capable of handling both flexible media and rigid substrates. In Fig. 1, the printer 1 operates in a first print mode, wherein the printer 1 is configured for transporting rigid substrates, such as the print medium 15. Such rigid print media 15 may be panels for doors, walls, etc., corrugated media, plates formed of plastic or metal, etc. To handle these rigid print media 15, the printer 1 in Fig. 1 is configured with a substantially linear transport path: from the media input device 14, the print medium 15 moves forward along the inkjet printing assembly 7 at a at substantially constant height. The media input unit 14 and the receiving unit are positioned at the level of the medium support surface of the belt 4. In Fig. 2, a flexible web medium 16 is supplied to the printer 1, which web medium 16 may be composed of e.g. paper, label stock, coated paper, plastic or textile. The web medium 16 is supplied from the input roller 2A and extends across the belt 4 to the take-up roller 2B, where the web medium 16 is re-wound. The printer 1 is configured to swiftly and efficiently switch between print modes.

Media loading

Fig. 3 shows the different, separate suction chambers 5A-C positioned underneath the belt 4, Each suction chambers 5A-C is connected to its respective pressure regulator 21-23. In the example in Figs 3 to 10, the first and third pressure regulators 21, 23 are configured to apply a relatively greater, negative pressure to respectively the first and third suction chambers 5A, 5C. The second pressure regulator 22 is configured to apply a relatively smaller, negative pressure to the intermediate suction chamber 5B. The intermediate suction chamber 5B is opposite the printing assembly 7.
Fig. 3 illustrates a step of bringing a leading edge of a web 16 from an input roller 2A towards the medium support surface of the belt 4. The medium support surface faces the print assembly 7 and extends over an open side of the suction chamber assembly 5 between the support rollers 3A, 3B. The suction chamber assembly 5 is divided into separate suction chambers 5A-5C by means of dividing walls perpendicular to the medium support surface. A pressure regulator system 20 is provided to control a pressure inside each of the suction chambers 5A-5C independent of the other. The pressure regulator system 20 comprises a respective pressure regulator 21-23 for each suction chamber 5A-5C. The pressure regulators 21-23 may comprise a fan, a pump, a (regulating) valve, etc. to set a pressure in the respective suction chamber 5A-5C. It will be appreciated that components, such as pumps or fans, may be shared by different suction chambers 5A-5C. In Fig. 3, the input roller 3A is rotated for unwinding the web 16. The rotation may be performed by a drive connected to the input roller 3A or by allowing the input roller 3A to rotate freely while pulling on the leading portion of the web 16. The leading portion of the web 16 is brought up to the medium support surface and positioned on the belt 4 at least over the first suction chamber 5A, as shown in Fig. 4. The step in Fig. 3 may be performed manually and/or loading aids for raising the leading edge to the belt 4 may be provided.
Fig. 4 and Fig. 8 illustrate the web 16 extending over the first suction chamber 5A and the step of applying a first, greater negative pressure to the first suction chamber 5A by means of the first pressure regulator 21. Thereby, the first suction chamber 5A is connected to a suction source, reducing the pressure inside the first suction chamber 5A. Thereby, the portion of the web 16 over the first suction chamber 5A is securely held onto the belt 4. The belt 4 is then driven by rotating one or more of the support rollers 3A-3B. This moves the leading edge of the web 16 further in the transport direction X. The input roller 3A herein also rotates, so that more web material is unwound from the input roller 3A. In the second chamber 5B downstream of the first suction chamber 5A, the pressure is atmospheric, though it will be appreciated that during this step of transporting the leading portion of the web 16 over the second suction chamber 5B a second, smaller negative pressure may be applied to the second suction chamber 5B as well. This transport step brings the web 16 over the second suction chamber 5B, preferably, so that it cover a substantial, major, or entire length of the second suction chamber 5B in the transport direction X, resulting in the situation shown in Fig. 5. It is noted that greater, negative pressures are relatively large as compared to the smaller negative pressure. The greater, negative pressures ensure that the print medium 16 is frictionally held against the belt 4. Where and when the smaller, negative pressure is applied to the print medium 16, the belt 4 is able to slide along the print medium 16, despite the normal force presses the belt 4 and the print medium together 16. It will be appreciated that the frictional properties of the print medium 16 and the belt 4 determine at which level the applied pressure results in reliable frictional holding. In practice, a pressure near atmospheric pressure may be applied for the smaller negative pressure, e.g. by utilizing a so-called high flow pump. The negative pressures may be achieved by using a so-called high pressure pump.
In Fig. 5, the print medium 16 is over the second chamber 5B, wherein its leading edge is still upstream of the downstream support roller 3B. As shown in Fig. 5 and Fig. 9, the leading portion comprises wrinkles and its leading edge is skewed with respect to the lateral direction of the belt 4, due to the loading operation.
In Fig. 5, the first, greater negative pressure is removed from the first suction chamber 5A by controlling the first pressure regulator 21 to bring the first suction chamber 5A to or near atmospheric pressure, for example by closing or significantly reducing its connection to a suction source. The second, smaller negative pressure is applied to the second suction chamber 5B by means of the second pressure regulator 22. Preferably, the second pressure regulator 22 is arranged to apply a relatively small negative pressure as compared to the first pressure regulator 21. When active, the smaller negative pressure in the second suction chamber 5B is closer to atmospheric than the active negative pressure applied to the first suction chamber 5A. The second pressure regulator 22 is preferably arranged to draw in a relatively high flow of air as compared to the first pressure regulator 21. Additionally, the input roller 3A is prevented from rotating. The input roller 3A may be angularly locked by blocking its motor and/or by a applying a separate locking mechanism, such as a clamp or other restrictor. In case of an electric motor, the current or voltage to the motor may be controlled, so that the torque exerted to the motor is opposite and equal to the tension in the print medium 16. The rotor of the motor is then fixed into one angular position. Alternatively, little to no current or voltage may be applied and the inertia of the motor is sufficient to prevent the input roller from rotating under forces exerted on it via the print medium 16. The one or more support rollers 3A-3B are driven, so that the belt 4 moves in the transport direction X. The relatively low negative pressure in the second suction chamber 5B allows the web 16 to slip with respect to the belt 4. The web 16 thus is substantially prevented from moving further in the transport direction X, since the input roller 3A is locked. The continued movement of the belt 4 slipping underneath the web 16 drives wrinkles towards the leading edge of the web 16 in the transport direction X. By driving the belt 4 for a sufficiently long period, wrinkles can thus be moved out of the leading portion. In consequence, the leading portion becomes flatly positioned on the belt 4, as shown in Fig. 6.
The slipping movement of the belt 4 along the leading portion further results in an alignment of the leading edge, the result of which is shown in Fig. 10. The leading edge of the print medium 16 has been cut perpendicular to the side edges of the print medium 16. By preventing the leading portion from moving in the transport direction, so that the belt 4 slips underneath it, the leading edge is re-oriented. After a sufficiently long period, the leading edge becomes positioned perpendicular to the transport direction of the belt 4. This aligns the leading edge with the rotation axis of the output roller 2B.
After aligning the leading edge, the relatively greater, negative pressures are applied in the first and third suction chambers 5A, 5C. Said greater negative pressures are sufficiently removed from atmospheric pressure, so that the belt 4 is unable to slip with respect to the print medium 16. The leading portion thus becomes held onto the belt 4. The belt 4 is then driven to bring the aligned leading edge to the output roller 2B. Skewing of the aligned leading edge is prevented, since the print medium 16 is securely held onto the belt 4. At the output roller 2B, the leading edge is attached to the output roller 2B, for example by taping or gluing. Since the leading edge has been aligned with output roller 2B due to the slipping of the belt 4 in Fig. 6, the leading edge can be attached to the output roller 2B without additional alignment steps. The leading portion of has also been flattened, so it is free of wrinkles. The wrinkle-free leading portion can thus be wound onto the output roller 2B. The absence of wrinkles ensures that the print medium is reliably transported and wound up neatly. This further allows printing on the leading portion, reducing media waste.
Fig. 11 illustrates different steps in a method of printing. In step i, it is determined whether the printer 1 will operate in its roll printing mode, specifically its roll-to-roll printing mode as illustrated and described with respect to Figs. 2 to 10. Alternatively, it may be determined that the printer 1 will operate in its rigid printing mode as described for Fig. 1. In case the roll printing mode is selected, a new roll of print medium 16 may be loaded onto the input roller 2A, in the optional step ii. In step iii, as illustrated in and discussed with respect to Fig. 3, the input roller 2A is rotated or allowed to rotate, so that print medium 16 is unwound from the respective roll. This allows the leading edge of the print medium 16 to be brought up to the transport belt 4. Therein, the leading edge is lifted upwards in the vertical direction Z.
Subsequently, in step iv, the leading portion of the print medium 16 is positioned on the upstream portion of the transport belt 4, as illustrated in Fig 4. The leading portion is positioned onto the transport belt 4, so that it remains in position there. Therein, the leading portion may be held onto the transport belt 4 by means of a negative pressure applied via the suction chamber assembly 5. In the example of Fig.4, a relatively great negative pressure is applied via the upstream suction chamber 5A, which provides a secure holding on the leading portion.
In step v, also illustrated in Fig. 4, a large negative pressure is applied to the leading portion via the transport belt 4, so that the leading portion is held onto the belt 4. Additionally, the transport belt 4 is driven into motion, for example activating a drive for rotating one of the support rollers 3A, 3B. Thereby, the leading portion is moved in the transport direction X until it is positioned over the intermediate suction chamber 5B. The leading edge is herein not transported past the downstream support roller 3B, preferably, not past the suction chamber assembly 5.
In step v, as illustrated in Fig. 5, the input roller 2A is locked, preventing it from rotating. This is one example of securing an upstream portion of the print medium 16. The print medium 16 may also be secured by clamping, fixing, locking it by other means upstream of the transport belt 4. In step vi, with the leading portion over the suction chamber assembly 5, a negative pressure is applied to the leading portion. This respective negative pressure is sufficiently small to allow the print medium 16 to slip with respect to the belt 4. In the example of Fig. 5, the relatively great negative pressure for holding the print medium 16 onto the belt 4 in the upstream suction chamber 5A is removed or disabled. The smaller negative pressure is applied in the intermediate suction chamber 5B. It is noted that the upstream and downstream suction chambers 5A, 5C herein are at or near atmospheric pressure. It will be appreciated that steps v and vi may be performed in any order or simultaneously.
In step vii, the transport belt 4 is driven while the print medium 16 is secured upstream and the smaller negative pressure is applied. In the example, in Fig. 5, the input roller 2A remains locked and the smaller negative pressure is applied in the intermediate suction chamber 5B. Additionally, the transport belt 4 is driven by actuating the respective support roller(s) 3A, 3B. Due to the small negative pressure, the belt 4 in step vii, slips along the bottom surface of the print medium 16. Contact between the print medium 16 and the moving belt 4 provides a constant force on the print medium 16, which drives wrinkles in the print medium 16 in the transport direction X. Wrinkles are thus "ironed" out towards the leading edge, where the wrinkles leave the print medium 16. Thereby, wrinkles are driven out of the leading portion. Additionally, the leading portion aligns itself with the transport direction X of the belt 4 due to the driving force.
The leading edge, (if cut straight) will thereby become aligned perpendicular to the transport direction. The leading edge thereby is oriented parallel to the lateral direction Y. Step vii is continued until the print medium 16 is de-wrinkled and the leading edge aligned in the lateral direction Y. The time required for de-wrinkled and re-orienting may vary per print medium type. Different times may be applied dependent on print medium type or a sufficiently long default period may be selected to cover multiple media types.
In step viii, as shown in Fig. 6, a relatively large negative pressure is applied to the print medium 16. In the example in Fig. 6, larger pressures are applied in the upstream and downstream suction chambers 5A, 5C. Additionally, the smaller pressure may also be applied in the intermediate chamber 5B to ensure the print medium 16 remains flat. The belt 4 is driven, so that the leading edge is brought to the take-up roller 2B. Then, in step ix, the leading edge is fixed to the roller 2B, for example by taping or clamping.
In step x, the print process is started. Print medium 16 is transported from the input roller 2A to the take-up roller 2B via the belt 4. Negative pressures may be applied via the required suction chambers 5A-5C. It will be appreciated that since the print medium as flattened printing may optionally also commence in step viii. When a roll has been depleted or a different print medium type is require, the steps ii to x may be repeated.
It will be appreciated that the different pressures can be applied by operating the user interface. The user interface may be provided with a visualization of the suction chamber assembly, wherein an operator may for example apply the desired pressure by pressing a button corresponding to said pressure chamber. A controller is provided to correspondingly control the pressure regulators 21-23. It will be appreciated that in the example in Figs. 3 to 10, the second, smaller negative pressure is closer to atmospheric than the greater negative pressure applied in the first and third suction chambers 5A, 5C. The second, smaller negative pressure is may be applied dependent on the applied print medium 16 or a standard value may be applied. The same applies mutatis mutandis to the greater negative pressure. Pressure values may be pre-stored on a memory of the printer's controller and automatically selected by based on the print job information and/or a pre-stored print media catalogue.
Although specific embodiments of the invention are illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations exist. It should be appreciated that the exemplary embodiment or exemplary embodiments are examples only and are not intended to limit the scope, applicability, or configuration in any way. Rather, the foregoing summary and detailed description will provide those skilled in the art with a convenient road map for implementing at least one exemplary embodiment, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope as set forth in the appended claims and their legal equivalents. Generally, this application is intended to cover any adaptations or variations of the specific embodiments discussed herein.
It will also be appreciated that in this document the terms "comprise", "comprising", "include", "including", "contain", "containing", "have", "having", and any variations thereof, are intended to be understood in an inclusive (i.e. non-exclusive) sense, such that the process, method, device, apparatus or system described herein is not limited to those features or parts or elements or steps recited but may include other elements, features, parts or steps not expressly listed or inherent to such process, method, article, or apparatus. Furthermore, the terms "a" and "an" used herein are intended to be understood as meaning one or more unless explicitly stated otherwise. Moreover, the terms "first", "second", "third", etc. are used merely as labels, and are not intended to impose numerical requirements on or to establish a certain ranking of importance of their objects.
The present 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 present 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

A method of loading a print medium (16) to a printer(1) comprising a printing assembly (7) configured to print an image on the print medium (16), a transport belt (4) configured to transport the print medium (16) to the printing assembly (7) in a transport direction (X) and a suction chamber assembly (5) configured to suck the print medium (16) on the transport belt (4), the method comprising the step of:
- applying a first negative pressure to the suction chamber assembly (5) while a leading portion of the print medium (16) is positioned on the transport belt (4) to draw the leading portion towards the transport belt (4),
characterized by the step of securing an upstream portion of the print medium (16) in the transport direction (X), while the first negative pressure is being applied and the transport belt (4) is moved with respect to the leading portion of the print medium (16) in the transport direction (X).
The method according to claim 1, wherein the first negative pressure is applied to the leading portion of the print medium (16), when the leading portion of the print medium (16) is positioned on the belt (4) over the suction chamber assembly (5).
The method according to any of the previous claims, wherein the moving belt (4) slips along the leading portion of the print medium (16).
The method according to claim 3, wherein the first negative pressure has been set and/or selected, such that the belt (4) and the leading portion of the print medium (16) are drawn towards one another while allowing these to slip along one another.
The method according to any of the previous claims, wherein the step of applying the first negative pressure and moving the belt (4) is performed at least until a leading edge of the print medium (16) is substantially aligned with respect to a lateral direction (Y) of the belt (4), preferably parallel thereto, and/or wrinkles in the print medium (16) have been substantially driven out of the print medium (16) in a transport direction (X) of the belt (4).
The method according to any of the previous claims, further comprising the steps of releasing an upstream portion of the print medium (16) and moving the print medium (16) by means of the belt (4) in a transport direction (X) of the belt (4).
The method according to any of the previous claims, further comprising:
- applying a second negative pressure to the suction chamber assembly (5), which second negative pressure is more negative than the first negative pressure;

- holding the print medium (16) securely on the belt (4) by means of the second negative pressure, so that the print medium (16) moves with the belt (4).
The method according to claim 6 or 7, wherein the print medium (16) is supplied from an input roller (2A) and the step of securing the print medium (16) comprises preventing rotation of the input roller (2A) and the step of releasing comprises allowing for rotation of the input roller (2A).
The method according to claim 8, wherein the step of moving the print medium (16) comprises unwinding the print medium (16) from the input roller (2A).
A printer comprising an endless, air permeable transport belt (4) extending along a suction chamber assembly (5) and a controller configured for performing the method according to any of the previous claims.