EP3370972A1

EP3370972A1 - Printing assembly and method of preventing a gaseous emission from the printing assembly entering a surroundings

Info

Publication number: EP3370972A1
Application number: EP16787855.2A
Authority: EP
Inventors: Edwin C. MULKENS
Original assignee: Oce Technologies BV
Current assignee: Canon Production Printing Netherlands BV
Priority date: 2015-11-06
Filing date: 2016-10-27
Publication date: 2018-09-12
Anticipated expiration: 2036-10-27
Also published as: WO2017076725A1; EP3370972B1

Abstract

In a printing assembly for providing an image on a medium, the printing assembly comprises a print station for providing a recording substance on the medium for forming the image. The recording substance releases a gaseous emission after application on the medium. An air stream supply unit and an air stream pick-up unit for generating an air stream from the air stream supply unit to the air stream pick-up unit are provided and arranged such that the air stream is positioned between a printed part of the medium, on which printed part the recording substance is provided, and a surroundings of the printing assembly. The air stream thus forms an air curtain preventing the gaseous emission from entering the surroundings.

Description

Printing assembly and method of preventing a gaseous emission from the printing assembly entering a surroundings

FIELD OF THE INVENTION

The present invention generally pertains to a printing assembly, wherein a gaseous emission is released.

BACKGROUND ART

A known printing assembly provides a recording substance on a recording medium in image dots such that the image dots together form an image. In a particular known printing assembly, the image dots are formed by applying droplets of a fluid curable recording substance. The recording substance is then cured by applying a suitable radiation, for example UV radiation. During curing, a chemical reaction initiated by the radiation results in solidification of the fluid recording substance. Further, chemical emissions are released. Such chemical emissions may create an undesirable smell and may even be harmful.

In other known printing assemblies, a solvent may be used in the recording substance and the solvent evaporates, when the recording substance is in contact with ambient air, for example after application on the recording medium. Such solvent may be water or may be a specific chemical composition. Evaporation of such a specific chemical composition may result in the above-mentioned undesirable smell and may even be harmful.

In case of water as a solvent, a high relative humidity in the surroundings of the printing assembly may likewise be undesirable. For example, if the recording medium is paper, the paper properties are strongly affected by the humidity. A humidity gradient in a paper web medium is likely to result in wrinkling and other deformations.

SUMMARY OF THE INVENTION

In an aspect of the present invention, a printing assembly according to claim 1 is provided. The printing assembly comprises a printing station, where a recording substance is provided on a medium for forming an image. After application on the medium, the recording substance releases a gaseous emission. The printing assembly further comprises an air stream supply unit and an air stream pick-up unit, which units are provided in the printing assembly for generating an air stream from the air stream supply unit to the air stream pick-up unit. The air stream is substantially planar and positioned between a printing assembly space and the surroundings. A printed part of the medium is the part of the medium on which the recording substance is applied. The printed part of the medium is arranged in the printing assembly space. It is noted that the printing assembly space is defined by the printing assembly, in particular, a printing station and a recording substance drying or curing unit are comprised in the printing assembly space. The air stream separates the surroundings from the printing assembly space. While it is common to apply a tangible housing to prevent gaseous emissions to the surroundings, the present invention applies an intangible housing by application of the air stream. In other words, the air stream replaces a part of the commonly known housing while preventing gaseous emissions entering the surroundings.

As from the moment of application and, where applicable, after irradiation by suitable curing radiation, the curing or drying recording substance on the printed part of the medium releases an amount of gaseous emission. Over time, the amount of emission decreases. While it is known from the prior art to attempt to retrieve any gaseous emission from the location of application, i.e. the printing station, the present invention aims at preventing any gaseous emission still being released after application on the medium from entering the surroundings. Thereto, an air curtain is generated between the print assembly space in which the printed part of the medium is arranged and the surroundings. In such an assembly, a gaseous emission cannot enter the surroundings as it would need to pass through the air curtain. However, as soon as the gaseous emission approaches the air curtain, it will be sucked into the air stream and will be retrieved together with the air stream in the air stream pick-up unit. As an advantage of the present invention, an operator is provided with a clear view on the medium and any image printed thereon without the risk of being subjected to the gaseous emission. Further, if a web medium is used, the operator can easily determine when a web medium receive unit is nearly full and the operator has simple and easy access to the printed part of the web medium. In particular for wide and very wide web mediums, for example a web medium having a width of about 3 meters or more, a receive roll with the printed medium is more easily taken out of the web medium receive station if there are no obstructing elements like any tangible housing parts.

As known in the art, an air curtain may be generated by supplying an air stream from an air stream supply unit. Such an air stream supply unit blows air, for example through a row of nozzles or through a slit. The air stream is then sucked into an air stream pick-up unit, preventing the stream to disintegrate, due to which the air would spread into the surroundings. Thus, using an air supply unit and an air pick-up unit, a substantially planar layer of flowing air is generated, thereby forming a curtain-like obstruction for any gaseous emission.

In an embodiment, the air stream pick-up unit is operatively coupled to an air treatment unit. The air treatment unit receives the air picked-up by the air stream pick-up unit and removes the gaseous emission from said air. Thus, cleaned harmless air may be supplied to the surroundings. In another embodiment, the air stream pick-up unit is operatively coupled to an air transport assembly, wherein the air transport assembly receives the air picked-up by the air stream pick-up unit. The air transport system then transports the air, including any gaseous emission, to a predetermined location, preferably away from the direct surroundings, for example to an outside environment.

In an embodiment, the printing assembly is configured to apply the recording substance on a web medium. In this embodiment, the printing assembly may comprise a web medium supply station from which a web medium is supplied to the printing station. In the printing station, the recording substance is provided on the web medium for forming the image. The printing assembly may further comprise a web medium receive station for receiving the web medium from the print station. The air stream is positioned between the web medium in the web medium receive unit and a surroundings of the printing assembly. In an embodiment, the air stream supply unit is arranged upstream of the print station and the air stream pick-up unit is arranged at a downstream end of the web medium receive station. Thus, the print station is also isolated from the surroundings, preventing any gaseous emission released in the print station to be released into the surroundings. In an embodiment, the web medium is fed from the web medium supply station to the web medium receive station in a transport direction and the web medium has a medium width in a width direction, the width direction being perpendicular to the transport direction. The air stream has an air stream width in the width direction, the air stream width being larger than the medium width. By ensuring that the air stream is wider than the web medium and thus the air stream extending in the width direction beyond both side edges of the web medium, virtually all gaseous emission may be captured in the air stream. In an embodiment, the web medium receive station comprises a receive roll for receiving the web medium on the receive roll and a guide roller upstream of the receive roll for guiding the web medium from the print station to the receive roll. A direction of movement of the web medium is changed by the guide roller when transported over the guide roller. In such embodiment, the air stream supply unit may be arranged upstream of the guide roller and the air stream pick-up unit may be arranged downstream of the guide roller. Arranging the air stream supply unit such that the air stream is directed at a surface of the guide roller, the air stream is guided over the guide roller by the Coanda effect. Thus, the air stream follows the direction of movement of the web medium and is guided towards the air pick-up unit. Using this Coanda effect, a change in direction of movement of the web medium forms no obstruction for using the air curtain according to the present invention to prevent a gaseous emission to enter the surroundings.

In an embodiment, the printing assembly according to the present invention comprises a medium support surface for stationary holding the medium, wherein the print station comprises a gantry extending in a scanning direction over the medium support surface and moveably arranged to be moved in a transport direction, the transport direction being perpendicular to the scanning direction; and a print head supported by the gantry. In this embodiment, one of the air supply unit and the air pick-up unit is arranged on the gantry and the other one of the air supply unit and the air pick-up unit is arranged at a circumference of the medium support surface for generating the air stream over the printed part of the medium. Thus, an air curtain is generated from the gantry, where the recording substance is applied on the medium, to a side of the medium support surface, thereby extending over the printed part of the medium. In a particular embodiment, the medium support surface has a width in the scanning direction and the air supply unit and the air pick-up unit each extend in the scanning direction over the width of the medium support surface. In such particular embodiment, the whole printed part is covered by the air curtain.

In another particular embodiment, the medium support surface extends in the transport direction from a first end to a second end. A first one of the air pick-up unit and the air supply unit is arranged at the first end of the medium support surface and a second one of the air pick-up unit and the air supply unit is arranged at the second end of the medium support surface, while at least one of the other one of the air pick-up unit and the air supply unit is arranged on the gantry. The medium support surface is divided in two parts by the gantry extending over the medium support surface. In this embodiment, both parts may be covered by an air curtain.

In an embodiment, the air supply unit and the air pick-up unit are arranged, in a direction perpendicular to the medium support surface, at a distance from the medium support surface. Thus, the air curtain is generated at a distance from the medium support surface, thereby preventing obstructions in the air stream, which might break the curtain.

In a more general aspect, the present invention provides a method of preventing a gaseous emission from a printing assembly entering a surroundings of the printing assembly, wherein the printing assembly provides a recording substance on a web medium for forming an image and the recording substance releases the gaseous emission after application on the web medium. This method comprises a step of generating an air stream between the web medium after application of the recording substance and the surroundings and a step of picking-up the air stream, wherein the air stream includes the gaseous emission. The air stream forms an air curtain protecting the surroundings from the gaseous emission and the air stream picks up the gaseous emission. In particular, the air stream including the gaseous emission may be conveyed to a predetermined location, such as a treatment unit or an outside environment, where the gaseous emission is harmless.

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. 1 A shows a perspective view of a first exemplary embodiment of an inkjet printing assembly;

Fig. 1 B shows a schematic representation of a scanning inkjet printing assembly; Fig. 1 C shows a perspective view of a second exemplary embodiment of an inkjet printing assembly;

Fig. 2A shows a cross-sectional schematic representation of a first embodiment of inkjet assembly similar to the embodiment of Fig. 1 A and adapted in accordance with the present invention;

Fig. 2B shows a cross-sectional schematic representation of a second embodiment of inkjet assembly similar to the embodiment of Fig. 1 A and adapted in accordance with the present invention;

Fig. 3A shows a cross-sectional schematic representation of a first embodiment of inkjet assembly similar to the embodiment of Fig. 1 C and adapted in accordance with the present invention;

Fig. 3B shows a cross-sectional schematic representation of a second embodiment of inkjet assembly similar to the embodiment of Fig. 1 C and adapted in accordance with the present invention; and

Fig. 3C shows a cross-sectional schematic representation of a third embodiment of inkjet assembly similar to the embodiment of Fig. 1 C and adapted in accordance with 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 inkjet printing assembly 36, wherein printing is achieved using a wide format inkjet printer. The wide-format inkjet printing assembly 36 comprises a housing 26, wherein the printing assembly, for example the ink jet printing assembly shown in Fig. 1 B is arranged. The inkjet printing assembly 36 also comprises a storage means for storing image receiving member 28, 30, a delivery station to collect the image receiving member 28, 30 after printing and storage means for marking material 20. In Fig. 1A, the delivery station is embodied as a delivery tray 32. Optionally, the delivery station may comprise processing means for processing the image receiving member 28, 30 after printing, e.g. a folder or a puncher. The wide-format inkjet printing assembly 36 furthermore comprises means for receiving print jobs and optionally means for manipulating print jobs. These means may include a user interface unit 24 and/or a control unit 34, for example a computer.

Images are printed on an image receiving member, for example paper, supplied by a roll 28, 30. The roll 28 is supported on the roll support R1 , while the roll 30 is supported on the roll support R2. Alternatively, cut sheet image receiving members may be used instead of rolls 28, 30 of image receiving member. Printed sheets of the image receiving member, cut off from the roll 28, 30, are deposited in the delivery tray 32.

Each one of the marking materials for use in the printing assembly are stored in four containers 20 arranged in fluid connection with the respective print heads for supplying marking material to said print heads.

The local user interface unit 24 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 24 is connected to a control unit 34 placed inside the printing apparatus 36. The control unit 34, for example a computer, comprises a processor adapted to issue commands to the print engine, for example for controlling the print process. The inkjet printing assembly 36 may optionally be connected to a network N. The connection to the network N is diagrammatically shown in the form of a cable 22, but nevertheless, the connection could be wireless. The inkjet printing assembly 36 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. 1 B shows an ink jet printing assembly 3. The ink jet printing assembly 3 comprises supporting means for supporting an image receiving member 2. The supporting means are shown in Fig. 1 B as a medium support surface 1 , but alternatively, the supporting means may be a flat surface. The medium support surface 1 , as depicted in Fig. 1 B, is a rotatable drum, which is rotatable about its axis as indicated by arrow A. The supporting means may be optionally provided with suction holes for holding the image receiving member in a fixed position with respect to the supporting means. The ink jet printing assembly 3 comprises print heads 4a - 4d, mounted on a scanning print head carriage 5. The scanning print head carriage 5 is guided by suitable guiding means 6, 7 to move in reciprocation in the main scanning direction B. Each print head 4a - 4d comprises an orifice surface 9, which orifice surface 9 is provided with at least one orifice 8. The print heads 4a - 4d are configured to eject droplets of marking material onto the image receiving member 2. The medium support surface 1 , the carriage 5 and the print heads 4a - 4d are controlled by suitable controlling means 10a, 10b and 10c, respectively. The image receiving member 2 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 2 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 2 is moved in the sub-scanning direction A by the medium support surface 1 along four print heads 4a - 4d provided with a fluid marking material.

The scanning print head carriage 5 carries the four print heads 4a - 4d and may be moved in reciprocation in the main scanning direction B parallel to the medium support surface 1 , such as to enable scanning of the image receiving member 2 in the main scanning direction B. Only four print heads 4a - 4d 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 4a - 4d per color of marking material is placed on the scanning print head carriage 5. For example, for a black-and-white printer, at least one print head 4a - 4d, 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 2. For a full-color printer, containing multiple colors, at least one print head 4a - 4d 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 4a - 4d containing black marking material may be provided on the scanning print head carriage 5 compared to print heads 4a - 4d containing marking material in any of the other colors. Alternatively, the print head 4a - 4d containing black marking material may be larger than any of the print heads 4a - 4d, containing a differently colored marking material. The print head carriage 5 is guided by guiding means 6, 7. These guiding means 6, 7 may be rods as depicted in Fig. 1 B. The rods may be driven by suitable driving means (not shown). Alternatively, the print head carriage 5 may be guided by other guiding means, such as an arm being able to move the print head carriage 5. Another alternative is to move the image receiving material 2 in the main scanning direction B. Each print head 4a - 4d comprises an orifice surface 9 having at least one orifice 8, in fluid communication with a pressure chamber containing fluid marking material provided in the print head 4a - 4d. On the orifice surface 9, a number of orifices 8 is arranged in a single linear array parallel to the sub-scanning direction A. Eight orifices 8 per print head 4a - 4d are depicted in Fig. 1 B, however obviously in a practical embodiment several hundreds of orifices 8 may be provided per print head 4a - 4d, optionally arranged in multiple arrays. As depicted in Fig. 1 B, the respective print heads 4a - 4d are placed parallel to each other such that corresponding orifices 8 of the respective print heads 4a - 4d 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 8, each of them being part of a different print head 4a - 4d. This parallel positioning of the print heads 4a - 4d with corresponding in-line placement of the orifices 8 is advantageous to increase productivity and/or improve print quality. Alternatively multiple print heads 4a - 4d may be placed on the print carriage adjacent to each other such that the orifices 8 of the respective print heads 4a - 4d 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 8.

Upon ejection of the marking material, some marking material may be spilled and stay on the orifice surface 9 of the print head 4a - 4d. The ink present on the orifice surface 9 may negatively influence the ejection of droplets and the placement of these droplets on the image receiving member 2. Therefore, it may be advantageous to remove excess of ink from the orifice surface 9. 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. 1 C shows another embodiment of an inkjet printing assembly 14 (herein also referred to as a printing apparatus), in which the medium support surface 1 is a flat surface. On the flat surface a flexible medium or a non-flexible flat medium may be arranged and may be printed on. The medium support surface 1 is supported on a suitable support structure 12 and a guide beam 16 is arranged over the medium support surface 1. Such guide beam 16 is also known in the art as a gantry. The guide beam 16 supports the print head carriage 5 such that the print head carriage 5 is enabled to scan in an X-direction. The guide beam 16 is arranged and configured to be enabled to reciprocate in a Y-direction, wherein the Y-direction is usually substantially

perpendicular to the X-direction. In a known printing apparatus 14, the guide beam 16 is also arranged and configured to be enabled to move in a Z-direction, which is substantially perpendicular to the X-direction and the Y-direction such to enable to adapt the printing apparatus 14 to a thickness of the recording medium being arranged on the medium support surface 1 and/or to be enabled to print multiple layers on top of each other such to generate height differences in a printed image.

Fig. 2A and 2B each show a cross-sectional view of a roll-to-roll printing assembly 36, wherein a web medium 38 is supplied from a supply roll 28 in a web medium supply station over a first guide roller 40 to a printing station 46 comprising a medium support surface 1 and a carriage 5 arranged over the medium support surface 1 . The web medium 38 is then supplied from the printing station 46 over a second guide roller 42 to a web medium receive station comprising a receive roll 44. In the illustrated

embodiments, the printing station 46 is covered by a housing 26. As a whole, either printing assembly 36 is arranged in a printing assembly space PAS, a virtual outline of which is indicated by a dotted line 60. The printing assembly space PAS has an open fluid connection to surroundings SUR. Only the housing 26 forms a tangible boundary between the printing assembly space PAS and the surroundings SUR.

Depending on the kind of recording substance used in the printing station 46, the carriage 5 may not only support a number of print heads 4a - 4d (as shown in Fig. 1 B), but may also support a curing means such as a UV radiation source for curing UV curable ink.

After depositing the recording substance on the web medium 38, the recording substance dries or is cured, due to which a gaseous emission GE1 is released downstream of the printing station 46. This release of the gaseous emission continues into the web medium receive station and is indicated by gaseous emission GE2. In order to prevent the gaseous emission to enter the surroundings SUR of the printing assembly, an air curtain is generated by an air stream supply unit 50 and an air stream pick-up unit 52. The air stream supply unit 50 generates a substantially planar air stream 54 by blowing through one or more nozzles or a slit and the air stream 54 is picked-up by the air pick-up unit 52. This substantially planar stream 54 of air blocks a flow path for the gaseous emission GE2 from one side of the air stream 54 (the side of the printing assembly) to another side of the air stream 54 (the side of the surroundings SUR), i.e. the air stream 54 may be considered to form an intangible housing with respect to gaseous emissions. As soon as the gaseous emission GE2 approaches the location of the air stream 54, the gaseous emission GE2 is drawn into the air stream 54 and is picked-up by the air pick-up unit 52.

In the embodiment of Fig. 2A, the gaseous emission GE1 generated downstream of the printing station 46 is caught by the housing 26. In an embodiment, a suction unit may suck air and the gaseous emission GE1 from the housing 26. In another embodiment, the gaseous emission GE1 will be drawn into the air stream 54 and be transported into the air pick-up unit 52 similar to the gaseous emission GE2. Whether the suction from the housing 26 by the air stream 54 is sufficient depends on the design of the housing 26, the suction strength of the air stream 54 (related to e.g. the flow rate, as apparent to those skilled in the art) and other properties of the inkjet printing assembly. In a particular embodiment, it may be considered to have the air supply unit 50 to draw air including the gaseous emission GE1 from the housing 26 and blow the air and gaseous emission to the air pick-up unit 52.

Due to the open character of the web medium receive station, a printer assembly operator is enabled to view the printed image on the web medium 38 easily and even from a distance and is enabled to easily remove the web medium receive roll 44.

In Fig. 2B another particular embodiment is shown, wherein the housing 26 does not extend over the second guide roller 42, while the air supply unit 50 is arranged over the carriage 5. The air stream 54 generated by the air supply unit 50 is directed at a surface of the second guide roller 42. As a consequence, the air stream is guided over the guide roller 42 by the Coanda effect, thereby following the direction of movement of the web medium 38. In this embodiment, compared to the embodiment of Fig. 2A, a larger part of the printed surface of the web medium 38 is visible to an operator, while the gaseous emissions GE1 and GE2 are prevented from entering the surroundings by the air curtain formed by the air stream 54.

Fig. 3A - 3C illustrate a flatbed printing assembly 14 similar to the printing assembly shown in Fig. 1 C. In the illustrated side view, the gantry 16 is moveable from left to right and the carriage 5 is moveable perpendicular to the plane of the drawing. In the drawings of Fig. 3A - 3C, it is suggested that the recording substance has been provided on a recording medium positioned on the medium support surface 1 . In particular, the recording substance is provided on the medium on the right-hand side of the carriage 5 and therefore a gaseous emission GE is released on the right-hand side of the carriage 5. However, depending on a direction of printing and corresponding moving of the gantry 16, the gaseous emission GE could likewise be on the left-hand side of the carriage 5, as will be apparent to those skilled in the art.

Referring to Fig. 3A, an air supply unit 50 is provided on the gantry 16 and blows a first air stream 54a to a first air pick-up unit 52a arranged at a first end of the medium support surface 1. Thus, an air curtain is provided over the medium support surface 1 at a location where a gaseous emission GE is released.

A second air curtain may be provided on the other side of the gantry 16: a second air stream 54b may be supplied from the air supply unit 50 to a second air pick-up unit 52b arranged at a second end of the medium support surface 1 . This second air curtain may only be generated when a gaseous emission is released on that side, determined by e.g. a specific sensor detecting such an emission or based on direction of movement of the gantry 16 as controlled by a printing assembly controller.

In practice, the medium support surface 1 has a width in the scanning direction (i.e. the direction in which the carriage 5 moves over the medium support surface 1 ). Preferably, in such a practical embodiment, the air supply unit 50 and the air pick-up unit 52a, 52b each extend in the scanning direction over the width of the medium support surface 1. Thus, the air curtain is provided over the full width of the medium support surface 1 and therewith over the whole area where a gaseous emission GE may be released.

Further, in practice, the air pick-up unit 52a, 52b is arranged at a distance from the medium support surface in a direction perpendicular to the medium support surface 1 to minimize influence on the air stream 54a, 54b. For example, an elevated recording medium might obstruct and deflect the air stream 54, if the air stream 54 would be close to the medium support surface 1 . By generating the air stream 54 at a distance, this obstruction or deflection may be prevented.

It is noted that the positions of the air supply unit 50 and the air pick-up unit 52a, 52b are exchangeable, as apparent to those skilled in the art. An air pick-up unit may be arranged on the gantry 16, while an air supply unit 50 may be provided on one or on both ends of the medium support surface 1 . In another embodiment shown in Fig. 3B, a stationary air pick-up unit 52b is arranged separated from the printing assembly 14. A first air supply unit is arranged at a first end of the medium support surface 1 and a generated first air stream 54a is received by a first air pick-up unit 52a arranged on the gantry 16. A second sir supply unit 50b is also arranged on the gantry 16 and generates a second air stream 54b that is received by the stationary air pick-up unit 52b. A third air supply unit 50c generates a third air stream 54c that is also received by the stationary air pick-up unit 52b. The three air streams 54a, 54b, 54c together form a closed air curtain covering the medium support surface 1 . The movement of the gantry 16 will not affect the air curtain.

If the gantry 16 moves towards the third air supply unit 50c and approaches the second end of the medium support surface 1 , the first air pick-up unit 52a and the second air supply unit 50b may be switched off. Another air stream 54d may then be generated streaming from the first air supply unit 50b to the stationary air pick-up unit 52b. Of course, if the first air supply unit 50a is positioned sufficiently higher relative to the medium support surface 1 , the other air stream 54d may replace the first and the second air streams 54a, 54b and the first air pick-up unit 52a and the second air supply unit 50b may be omitted, since the gantry 16 will in such embodiment not interfere with the other air stream 54d.

Similar to the embodiment of Fig. 3A, it is noted that the air supply units and the air pick- up units are exchangeable due to which the direction of the air streams would become reversed. Such an embodiment is shown in Fig. 3C. Further, compared to the embodiment of Fig. 3B, the air supply unit 50a is not arranged at an end of the medium support surface 1 , but more over a central part of the medium support surface 1. Apart from the direction of the air streams and the position of the stationary unit (Fig. 3B: air pick-up unit 52b; Fig. 3C: air supply unit 50a), the embodiments of Fig. 3B and 3C are quite similar and function essentially similarly.

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. For example, the present invention may be employed in any printer assembly wherein a printed medium is not covered by a printer housing, or the like, such as (but not limited to) a hybrid printer in which a rigid medium may be transported through a print station by a suitable pinch, or the like.

Further, it is noted that features presented and described in separate dependent claims may be applied in combination and any advantageous combination of such claims are herewith disclosed.

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

A printing assembly for providing an image on a medium, the printing assembly comprising:

a) a print station for providing a recording substance on the medium for forming the image, the recording substance releasing a gaseous emission after application on the medium; and

b) an air stream supply unit and an air stream pick-up unit for generating an air stream from the air stream supply unit to the air stream pick-up unit, wherein the printing assembly defines a printing assembly space and a

surroundings, the printing assembly being positioned in said printing assembly space and the printing assembly space having an open fluid connection to the surroundings,

the air stream being substantially planar and being positioned between a printed part of the medium arranged in the printing assembly space, on which printed part the recording substance is provided, and the surroundings.

The printing assembly according to claim 1 , wherein the air stream pick-up unit is operatively coupled to an air treatment unit, the air treatment unit receiving the air picked-up by the air stream pick-up unit and the air treatment unit removing the gaseous emission from said air.

The printing assembly according to claim 1 , wherein the air stream pick-up unit is operatively coupled to an air transport assembly, the air transport assembly receiving the air picked-up by the air stream pick-up unit and the air transport system transporting the said air including gaseous emission to a predetermined location.

The printing assembly according to claim 1 , wherein the printing assembly is configured for providing an image on a web medium, the printing assembly comprising:

c) a web medium supply station for supplying the web medium to the print station; and

d) a web medium receive station for receiving the printed part of the web medium from the print station.

The printing assembly according to claim 4, wherein

• the web medium is fed from the web medium supply station to the web medium receive station in a transport direction;

• the web medium has a medium width in a width direction, the width direction being perpendicular to the transport direction; and

• the air stream has an air stream width in the width direction, the air stream width being larger than the medium width.

The printing assembly according to claim 4, wherein

• the web medium receive station comprises a receive roll for receiving the web medium on the receive roll and a guide roller upstream of the receive roll for guiding the web medium from the print station to the receive roll, a direction of movement of the web medium being changed when transported over the guide roller,

• the air stream supply unit being arranged upstream of the guide roller;

• the air stream pick-up unit being arranged downstream of the guide roller;

• the air stream supply unit being arranged such that the air stream is directed at a surface of the guide roller and the air stream is guided over the guide roller by the Coanda effect, thereby following the direction of movement of the web medium.

The printing assembly according to claim 4, wherein the air stream supply unit is arranged upstream of the print station and the air stream pick-up unit is arranged at a downstream end of the web medium receive station.

The printing assembly according to claim 1 , wherein the printing assembly further comprises

c) a medium support surface for stationary holding the medium; and

wherein the print station comprises

d) a gantry extending in a scanning direction over the medium support surface and moveably arranged to be moved in a transport direction, the transport direction being perpendicular to the scanning direction; and

e) a print head supported by the gantry; wherein one of the air supply unit and the air pick-up unit is arranged on the gantry and the other one of the air supply unit and the air pick-up unit is arranged at a circumference of the medium support surface for generating the air stream over the printed part of the medium.

9. The printing assembly according to claim 8, wherein the medium support surface has a width in the scanning direction and wherein the air supply unit and the air pick-up unit each extend in the scanning direction over the width of the medium support surface.

The printing assembly according to claim 8, wherein the medium support surface extends in the transport direction from a first end to a second end and wherein a first air pick-up unit is arranged at the first end of the medium support surface and a second air pick-up unit is arranged at the second end of the medium support surface.

The printing assembly according to claim 8, wherein the air supply unit and the air pick-up unit are arranged in a direction perpendicular to the medium support surface at a distance from the medium support surface.

Method of preventing a gaseous emission from a printing assembly entering a surroundings of the printing assembly, wherein the printing assembly is arranged in a printing assembly space and provides a recording substance on a medium for forming an image, the recording substance releasing the gaseous emission after application on the medium, the method comprising:

a) generating asubstantially planar air stream between the medium after

application of the recording substance and the surroundings; and

b) picking-up the air stream, the air stream including the gaseous emission.