Media conveyance system

Abstract

 A conveyance system for use in conveying a media object past a plurality of fluid deposition devices in a predetermined conveyance direction is provided. The conveyance system comprises a plurality of elongate apertures (240A,240B,240C) for receiving excess fluid from the fluid deposition devices, each aperture extending in a direction orthogonal to the conveyance direction (190) and a plurality of conveyance mechanisms aligned with the plurality of elongate apertures in the conveyance direction, each mechanism being adapted to convey at least a portion of a media object (140) in the conveyance direction. The conveyance system is arranged such that one end of each conveyance mechanism terminates adjacent to a corresponding elongate aperture in the conveyance direction and each elongate aperture terminates adjacent to at least one neighbouring conveyance mechanism in a direction orthogonal to the conveyance direction.

Description

[0001] The present invention relates to the conveyance of a media object. In particular, the present invention relates to a system for conveying a media object to enable the deposition on to the object of a fluid or liquid such as varnish, glue, ink or the like.

[0002] In the field of industrial printing, large-scale, flexible printing systems often have a number of discrete stages to produce an output. For example, a typical printing system may include a stage for the application of a priming agent, a stage for the application of ink, a stage for the application of varnish and a stage for the application of a finishing agent. In certain circumstances the fluid may also comprise a gas, for example a gas chosen to condense on, or induce a chemical reaction at, the surface of the media object.

[0003] In such systems, each stage typically comprises a linear path along which one or more media objects travel. As a particular media object travels along the path, a fluid may be applied to the media object using specialised fluid deposition devices arranged either above or below the path. Many modern fluid deposition devices are able to digitally deposit a fluid on a passing media object, i.e. the fluid is applied to the media object using a plurality of fluid deposition nozzles that each deposit a unit of fluid over a small discrete area. The small discrete area may be likened to a pixel, as used in conventional colour or greyscale imaging systems. Hence, fluid may be deposited on a media object in accordance with data in the form of a deposition "image" made up of a plurality of pixels in at least two-dimensions. In the present context, the terms "image" and "pixel" should be interpreted more broadly than their use in conventional colour or greyscale imaging systems; for example, the terms may relate to areas of varnish or glue upon a media object (or the data that dictates the deposition of said areas) as well as relating to areas of contrast, colour or ink deposition.

[0004] A typical technology used in the printing stage is inkjet printing. Inkjet printing may utilise one or more lines of inkjet printing heads, wherein in most case these lines extend across the path of the media object, i.e. perpendicular to the direction of transport of a media object along the path of the printing stage. Each line of heads may be adapted to print a particular colour separation layer. As a media object passes along the path, these heads deposit ink upon the object, generating a two-dimensional image in one or more colours.

[0005] For stages other than printing, inkjet technology has recently been adapted to digitally apply other fluids such as varnish or glue to predefined areas of a media object. For example, an A3 paper size poster may require the deposition of varnish in a particular area of the poster relating to a company logo; thus appropriate configuration information is supplied to the printing system in the form of a printing configuration file or deposition "image" and the system controls the fluid deposition devices accordingly.

[0006] In a printing system such as that described above, the media object, i.e. the substrate for fluid deposition, needs to be controlled in all three spatial dimensions. In the following description the three spatial dimensions will be referred to as the X, Y and Z directions; wherein the X direction is aligned with the direction of transport, the Y direction is aligned with a direction orthogonal to the direction of transport in the plane of the conveyance path, and the Z direction is aligned with a direction perpendicular to the plane of the conveyance path.

[0007] For example, as the fluid deposition devices are typically fixed in a static position relative to the path of the media object, the media object must be correctly aligned in the X and Y directions, i.e. in a plane parallel to the conveyance path, to correctly deposit fluid in the appropriate areas. If control in the X and Y directions is not achieved the fluid may be deposited in the wrong areas of the media object or may miss the media object altogether and be deposited on the conveyance path.

[0008] Control of the media object is also required in the Z direction. Nearly all fluid deposition devices are designed to deposit fluid on a flat, i.e. approximately two-dimensional, surface. The bending of a media object, i.e. a non-planar profile parallel to the X and Y directions, causes incorrect deposition of fluid or may cause jams in the printing system. For example, fluid may be incorrectly deposited on the underside of curled corners or raised portions of the media object may not be able to pass under the deposition devices. This typically leads to a less than a satisfactory output which must be destroyed.

[0009] As well as requiring the control of a media object in three dimensions, modern printing systems are also required to deposit fluid within the full area of the media object, so-called "edge-less" deposition. While this may produce more aesthetically pleasing output, avoid the need for trimming and reduce waste, it also places extra demands on the printing system. In order to perform such deposition, fluid deposited near the edges of the media object is often also sprayed onto neighbouring regions of the conveyance path. If this fluid is retained on the conveyance system then there is a high risk of subsequent media objects becoming contaminated. This risk is further increased if the fluid has a viscous consistency

[0010] In the field of inkjet printing, US patent 7,083,274 B2 and European patent application EP1717175 A1 disclose inkjet recording apparatus with a particular arrangement of conveying belts to facilitate the printing process. In these systems, a plurality of inkjet printing heads are disposed in a paper conveyance direction wherein particular recording head units are configured and disposed in a staggered manner. The media object conveying means has first and second conveying portions connected in the conveying direction of the media object. A plurality of conveying belts are arranged by mutually keeping a predetermined interval between the belts, in which the conveying belts of the first and second conveying portions are set so that an other-hand conveying belt is located between one-hand conveying belts. The inkjet recording heads are then aligned above the gaps between the belts.

[0011] US7,083,274 B2, and related application US7,144,097 B2, also disclose head cleaning devices that are positioned underneath the inkjet recording heads. These devices are adapted to clean the said heads and to receive "dummy" jets of ink that are released in between passing sheets of media objects.

[0012] The prior art referenced above, while improving the deposition of fluid in the particular field of inkjet printing, provide systems that lack adequate control in all three axes. In particular, the arrangement of conveying belts and printing heads do not provide adequate control in the Z direction i.e. perpendicular to the plane of the media object and conveyance path. This leads to incorrect printing and rejected output. Additionally, these prior art systems do not take into account the problems associated with applying fluids near the edges of media objects. Hence, what is required is a conveyance system that provides adequate control in all three axes, i.e. X, Y and Z directions, whilst still enabling deposition of fluid across the complete are of the media object. Such a system would also need to maintain high throughput and high quality output.

[0013] According to a first aspect of the present invention, there is provided a conveyance system for use in conveying a media object past a plurality of fluid deposition devices in a predetermined conveyance direction. The conveyance system comprises a plurality of elongate apertures for receiving excess fluid from the fluid deposition devices, each aperture extending in a direction orthogonal to the conveyance direction; and a plurality of conveyance mechanisms aligned with the plurality of elongate apertures in the conveyance direction, each mechanism being adapted to convey at least a portion of a media object in the conveyance direction; wherein one end of each conveyance mechanism terminates adjacent to a corresponding elongate aperture in the conveyance direction and each elongate aperture terminates adjacent to at least one neighbouring conveyance mechanism in a direction orthogonal to the conveyance direction.

[0014] Such a conveyance system tightly clusters the conveyance mechanisms in the predetermined conveyance direction whilst still providing means to prevent the deposition of excess fluid on the conveyance means itself (e.g. belts or rollers). By arranging each conveyance mechanism so that it terminates adjacent to a corresponding elongate aperture and each elongate aperture so that it terminates adjacent to at least one neighbouring conveyance mechanism, the effect of the discontinuities in the conveyance path provided by the apertures is minimised and thus control in both the X, Y plane and the Z direction is maintained. Furthermore, the tight clustering of the conveyance mechanisms around the elongate apertures reduces curling and bending effects in the Z direction and thus provides high quality output. The tight clustering of the conveyance mechanisms also prevents movement of the media object in the direction orthogonal to the conveyance direction in the plane of the conveyance path, i.e. the Y direction (known as "crabbing"). Preferably, the fluid deposition devices are aligned with the apertures.

[0015] In a preferred embodiment of the present invention, at least one elongate aperture terminates adjacent to a respective neighbouring conveyance mechanism at each end of the aperture in a direction orthogonal to the conveyance direction. Hence, in a system that uses three elongate lines of belts, rollers or the like in the conveyance direction, at least one elongate aperture is surrounded by active conveyance mechanisms (i.e. mechanisms supplying a moving force to the media object).

[0016] In another preferred embodiment, each elongate aperture is relatively offset in the conveyance direction from an immediately neighbouring elongate aperture. This produces a set of staggered apertures in the direction orthogonal to the conveyance direction, producing a "zig-zag" arrangement in that direction. Such an arrangement enables an active conveyance mechanism to be positioned both to the left and right of an aperture in a direction orthogonal to the conveyance direction. This increases control of the media object and reduces the likelihood of curling or bending in the Z direction.

[0017] In a particular embodiment, the plurality of apertures are in communication with one or more fluid receptacles for receiving excess fluid. In the case where a single fluid receptacle is used, a manifold may be provided to collect the excess fluid into a common trough or receptacle which may be emptied as required. Alternatively, depending upon the design of the conveyance system, each aperture may be in communication with a respective fluid receptacle, which may be emptied individually, or two or more receptacles wherein each receptacle is in communication with a chosen number of apertures.

[0018] In one embodiment, for each elongate aperture, a first conveying mechanism terminates adjacent to a first side and a second conveying mechanism terminates adjacent to a second, opposite, side. In this arrangement, at least one aperture will be completely surrounded by active conveyance mechanisms increasing the control of the media objects along the path.

[0019] In a preferred embodiment, the conveyance system further comprises a plurality of plates for supporting the media object during conveyance across a respective elongate aperture. In this embodiment, each plate may comprise one or more apertures in communication, preferably aligned, with the elongate aperture and one or more flanges that extend away from elongate aperture in the direction of one or more respective neighbouring conveyance mechanisms. Hence, the effect of the aperture or discontinuity in the conveyance path is further reduced by the use of the plate which helps prevent unwanted movement in the Z direction.

[0020] In particular variations of the above embodiment, each plate further comprises a locking mechanism for removably mounting the plate within a respective aperture. This locking mechanism may comprise elastically deformable arms that, in use, mate with the walls of a channel extending from each elongate aperture or alternatively may comprise frictional mounts that are retained within a channel extending from each elongate aperture using frictional forces. By removably mounting the plates using any of the mechanisms described above, or indeed any other suitable mechanism, the plate may be easily removed for cleaning, repair or replacement. Preferably, each plate comprises sintered glass-loaded nylon, which provides a hard wearing surface.

[0021] In certain embodiments, each aperture is less than 20 millimetres wide, i.e. the width of the aperture in the conveyance direction is less than 20 millimetres.

[0022] In certain embodiments, the conveyance system comprises a retention system to hold a media object in place during conveyance. This retention system may comprise a vacuum system that provides a pressure differential along the length of each elongate aperture and within each conveyance mechanism, or in other embodiments may comprise other systems such as electro-static or mechanical retention systems. When using such a system, the media object is retained on the conveyance path to prevent movement in the X, Y and Z directions. If the conveyance mechanisms comprise permeable belts or a mesh-like fabric, a sheet of substrate can be retained on the surface of the belt or mesh during conveyance. This particularly reduces movement in the Z direction. By maintaining the vacuum within the elongate aperture, further movement in the Z direction caused by the discontinuity is reduced and the conveyance of excess fluid away from the surface of the conveyance system is facilitated.

[0023] In certain embodiments, the length of each elongate aperture is substantially equal to the width of each aligned conveyance mechanism. This makes it easier to tightly cluster the conveyance mechanism around each aperture.

[0024] In a particular embodiment, each conveyance mechanism comprises a driven belt. The conveyance system may comprise a plurality of conveyance paths extending in the conveyance direction. Each path may comprise two conveyance mechanisms having respective driven belts and may provide a driving force in the conveyance direction. The plurality of conveyance paths, in total, form a larger overall conveyance or transport path.

[0025] In this embodiment, the plurality of conveyance paths subdivide the overall conveyance path, wherein each of the plurality of conveyance paths may be thought of as a linear axis in which direction two or more conveyance mechanisms are extended to transport a media object (such as a sheet of paper or other substrate) in the conveyance direction. In the present embodiment, a first belt is positioned before a respective elongate aperture in the conveyance direction and a second belt is positioned after the elongate aperture in the conveyance direction, wherein a first set of conveyance paths comprises one or more elongate apertures extending in a first line in a direction orthogonal to the conveyance direction and second set of conveyance paths comprise one or more elongate apertures extending in a second line in a direction orthogonal to the conveyance direction. The first line and second line being relatively offset from each other in the conveyance direction, and the second set of conveyance paths being interleaved with the first set of conveyance paths in a direction orthogonal to the conveyance direction.

[0026] In a variation of the above embodiment, the conveyance system may further comprise three of more axles extending in a direction orthogonal to the conveyance direction, wherein, for the first set of conveyance paths, a first axle supports each belt that terminates adjacent to the first side of each aperture and a second axle supports each belt that terminates adjacent to a second side of each aperture; and for the second set of conveyance paths, the second axle supports each belt that terminates adjacent to the first side of each aperture and a third axle supports each belt that terminates adjacent to a second side of each aperture. This three axle design reduces the complexity of the conveyance system and allows the conveyance mechanisms to be tightly clustered with the minimum amount of mechanical hardware.

[0027] In an alternative embodiment, the conveyance system comprises a plurality of conveyance paths of a common, predetermined width extending in the conveyance direction, wherein each path comprises a conveyance mechanism having a driven belt and a respective elongate aperture. Preferably, a first set of conveyance paths has elongate apertures extending in a first line in a direction orthogonal to the conveyance direction, the corresponding conveyance mechanism being positioned at a first side of said apertures; and a second set of conveyance paths has elongate apertures extending in a second line in a direction orthogonal to the conveyance direction, the corresponding conveyance mechanism being positioned at a second side of said apertures, the second set of conveyance paths being interleaved with the first set of conveyance paths in a direction orthogonal to the conveyance direction, wherein the apertures of each set of conveyance paths are relatively offset from each other in the conveyance direction. This arrangement again maximises control in all three dimensions. Such a design also facilitates the manufacture of the conveyance system as a single unit of a predetermined width, wherein such a system may be removably mounted as said single unit in a fluid deposition system.

[0028] In a preferred variation of the above embodiment, each conveyance mechanism may comprise a vacuum chamber, around which a driven belt is rotatably mounted, and a drive axle common to all conveyance mechanisms. The conveyance mechanism may also further comprise a tension device for maintaining the tension of the drive belt and each vacuum chamber may be in communication with the vacuum chamber of at least one neighbouring conveyance mechanism.

[0029] The above conveyance mechanism provides a number of advantages. Firstly, it allows the conveyance mechanism to be of a small size and so facilitates the mounting of the conveyance mechanism in a single removable unit. Secondly, the conveyance mechanism allows the application of a vacuum force right up until the termination of the belt before the elongate aperture. In embodiments that use an axle at each end of the conveyance mechanism, no vacuum force can be applied around the area of the axle. This problem is addressed by the aforementioned conveyance mechanism wherein the drive axle may be positioned below the vacuum chamber. Thirdly, this embodiment only requires a single drive axle to provide a driving force for all of the conveyance mechanisms.

[0030] In a preferred embodiment, the conveyance system further comprises a fluid receptacle extending in a direction orthogonal to the conveyance direction, wherein the fluid receptacle is in communication with each elongate aperture. This enables excess fluid to be deposited in a single receptacle which may be emptied when required.

[0031] In a particular embodiment, the fluid is a varnish to be applied to the media object. If varnish is used this may be applied as an aerosol. In other embodiments, the fluid may be ink, glue, any other known liquid, gas or paste, or a combination of any of the above, for example any known aerosol.

[0032] According to a second aspect of the present invention, a fluid deposition system for depositing fluid on a media object comprises a plurality of fluid deposition devices extending in a direction orthogonal to a conveyance direction of the media object and any conveyance system as described previously. In this fluid deposition system, each elongate aperture within the conveyance system is positioned opposite a corresponding fluid deposition device. In certain embodiments, each fluid deposition device is mounted less than 20 millimetres from a respective elongate aperture. By positioning the fluid deposition heads closely above the elongate apertures, the risk of spraying excess fluid onto the conveyance mechanisms and thus disrupting the deposition process is minimised.

[0033] In a third aspect of the present invention, a variation of the second aspect is provided, wherein the conveyance system is removably mounted as a single unit with the fluid deposition system. This facilitates repair and maintenance and provides a modular system.

[0034] Embodiments of the present invention will now be described in relation to the accompanying drawings, in which:-

[0035] Figure 1 is a schematic illustration of an exemplary fluid deposition system for use with the present invention;

[0036] Figure 2 is a schematic plan view of an exemplary conveyance system according to a first embodiment of the present invention;

[0037] Figures 3A and 3B are respective side views through cross-sections A-A' and B-B' as shown in Figure 2;

[0038] Figure 4A is a schematic plan view of an exemplary complete system according to a second embodiment of the present invention;

[0039] Figure 4B is a schematic side view of the second embodiment showing the mounting of fluid deposition heads;

[0040] Figure 4C is a schematic plan view of the second embodiment showing the mounting of the fluid deposition heads;

[0041] Figure 5A is a perspective view of an exemplary plate and associated plate mounting that may be used in a third embodiment of the present invention;

[0042] Figure 5B is perspective view of the plate in situ within the conveyance system;

[0043] Figure 5C is a schematic side view of the plate in situ within the conveyance system;

[0044] Figure 5D is a perspective view showing the plate in situ together with a mounted fluid deposition head;

[0045] Figure 6A is a perspective view of an exemplary conveyance system according to a fourth embodiment of the present invention;

[0046] Figure 6B is a further perspective view of the fourth embodiment showing the conveyance system mounted in situ; and

[0047] Figure 7 is a cut-away section of the conveyance system of the fourth embodiment showing the components of an individual conveyance mechanism.

[0048] Figure 1 shows a schematic view of an exemplary fluid deposition system 100 that may be used with the present invention. The system comprises media input means 110, conveyance path 120, and media output means 130. Media input means 110 is adapted to supply a media object 140 to the conveyance path 120; for example, the media input means 110 may comprise a media object storage stack and feed mechanism or may simply comprise the beginning of conveyance means for the system 100. The media object 140 may comprise any substrate suitable for fluid deposition, such as paper, cardboard, polymer, fabric, wood, metal or the like. Media object 140 may be of any size or shape. The media object 140 travels along the conveyance path 120 in a conveyance direction 190 to the media output means 130. In the present example, the conveyance direction 190 is substantially aligned with an "X" axis and a direction perpendicular to the plane of the media object 140 is aligned with a "Z" axis. The media output means 130 may comprise means to stack media objects 140 received from the conveyance path 120 or may comprise suitable apparatus to prepare the media object 140 for transfer to a further media input means present within a further stage of production.

[0049] During transport of the media object 140 in the conveyance direction 190, fluid may be deposited at selected locations on the media object 140 using deposition device 150. Deposition device 150 may comprise any number of discrete fluid deposition devices known in the art to enable fluid to be deposited upon a media object. For example, deposition device 150 may comprise a plurality of deposition heads. Each deposition head may then comprise a plurality of electro-mechanical actuators that are configured to eject liquid from one or more nozzles aligned in a direction perpendicular to the conveyance direction 190 in the plane of the media object 140. The deposition device 150 may comprise one or more rows of such deposition heads in the X, or conveyance, direction and may be adapted to deposit any one of a number of fluids, including but not limited to, varnish, glue, ink or the like.

[0050] Opposite the deposition device 150 is positioned a waste system 160 for collecting excess fluid ejected from the deposition device 150. This fluid may comprise fluid that was not deposited on a media object 140, for example, fluid deposited beyond the edge of a media object or fluid ejected from the deposition device 150 in the absence of a media object. In the present discussion, the waste system 160 comprises a portion of the present invention. In the example of Figure 1, the waste system 160 is connected to a retention system 170. Retention system 170 is also connected to retention devices 180A and 180B that are located in proximity to the conveyance path 120. The retention system 170 may be based on one of a variety of technologies including, but not limited to, those utilising friction forces, electrostatic forces or non-electrostatic forces such as suction, adhesion and the like. In the present example, the retention system comprises a vacuum system that provides a pressure differential across the conveyance path 120 to retain the media object 140 upon the path. In this case, retention devices 180A and 180B comprise vacuum chambers located underneath the conveyance path 120. These chambers are maintained at a low pressure to provide a downwards force at the surface of the path 120 to hold the media object 140 onto the path. The application of a vacuum to the waste system 160 draws excess fluid from the conveyance path 120.

[0051] An exemplary conveyance system according to a first embodiment of the present invention is shown in Figure 2. The conveyance system 200 implements the path 120 for conveying a media object 140 in the conveyance direction 190. The conveyance system 200 comprises a plurality of belts 220, 230 and a plurality of elongate apertures 240 arranged upon a chassis 210. In other embodiments, the belts may be replaced with other suitable conveyance mechanisms such as rollers, linear drive mechanisms or the like without deviating from the scope of the present invention. Each elongate aperture extends in a direction (Y) orthogonal to the conveyance direction, i.e. the length of each aperture in said direction is greater than its width in the conveyance direction. The belts and apertures are arranged to form three conveyance paths subsections A, B and C. Each subsection comprises a first belt 220, an aperture 240, and a second belt 230. Each conveyance path subsection transports a media object 140 in the conveyance direction 190. In some, but not all, uses, the width of each belt section and elongate aperture in the direction (Y) orthogonal to the conveyance direction 190 is less than the width of the media object 140 in the same direction. If this is the case then, in use, a media object 140 will extend over multiple conveyance path subsections as shown in Figure 2. However, this depends on the media object used for the current deposition run and may not be the case in all circumstances.

[0052] The elongate apertures 240 are arranged in a staggered formation in the conveyance direction 190; i.e. are offset relative to each other in that direction. One end of each of the belt sections 220 and 230 terminates adjacent to a corresponding aperture 240. For example, in Figure 2, belt section 220A terminates to the left of elongate aperture 240A and belt section 230A terminates to the right of the same aperture. In a preferred embodiment, the distance from the end of each belt section 220, 230, to the edge of each elongate aperture 240 is minimised so that each belt subsection abuts the aperture. This minimises the effect of any areas of the conveyance path where it is not possible to control or retain the media object 140. In one implementation of the present invention the distance between the furthest curvature of each belt section 220, 230 is 10 mm, e.g. between the right-hand edge of belt section 220A and the left-hand edge of belt section 230A in Figure 2.

[0053] Conveyance path subsection A comprises a first belt 220A, elongate aperture 240A and a second belt 230A. Belt 220A is mounted upon a first axle 255 and a third axle 265. Belt 230A is mounted upon a fourth axle 270 and a fifth axle 275. In the present example, axles 265 and 270 are driven by a motor and gearing system (not shown) located within the chassis 210, thus moving belt subsection 220A and 230A in the conveyance direction 190. Axles 255 and 275 may be idle, i.e. free to rotate without a driving torque. In other embodiments, it is also possible for axles 255 and/or 275 to be driven instead of or as well as axles 260, 265 and 270.

[0054] Conveyance path subsection B comprises a first belt 220B, elongate aperture 240B and a second belt 230B. Belt 220B is mounted upon the first axle 255 and a second axle 260. Belt 230B is mounted upon the third axle 265 and the fifth axle 275. Conveyance path subsection C comprises a first belt 220C, elongate aperture 240C and a second belt 230C. Belt 220C is mounted upon the first axle 255 and the third axle 265. Belt 230C is mounted upon the fourth axle 270 and the fifth axle 275. Axles 265 and 270 thus respectively drive belts 220C and 230C, whereas belt 220B is driven by axle 260 and belt 230B is driven by axle 265. An appropriate gearing system (not shown) may connect axles 260, 265 and 270. Each belt 220 and 230 comprises a number of small openings 215 that allow a vacuum to be applied to the conveyance path to retain a media object 140. Below elongate apertures 240, an excess fluid receptacle 250 is mounted within the chassis 210.

[0055] Figure 3A shows a cross-section through line A-A' of Figure 2. Hence, first belt 220A is mounted around axles 255 and 265 and second belt 230A is mounted around axles 270 and 275. Elongate aperture 240A is then positioned between the end of first belt 220A and the end of second belt 230A. Elongate aperture 240A is in communication with fluid receptacle 250. Fluid receptacle 250 is adapted to store excess fluid ejected from a fluid deposition head 310A mounted above the aperture. In use, a media object 140 is transported in direction 190 along first belt 220A across aperture 240A and then onto second belt 230A. While the media object 140 passes under fluid deposition head 310A, fluid is applied to the object. Any excess fluid from this deposition process, which may be fluid that is not deposited on the media object 140, passes across the gap between the head and the aperture into the aperture. Such fluid then flows along a channel 330, for example under the force of gravity, into the receptacle 250. The fluid receptacle 250 is in communication with each aperture 240 via a number of channels 330 that project upwards from the receptacle 250.

[0056] To retain the media object 140 upon the belt subsection 220A and 230A, pressure chambers 380A and 380B are respectively mounted within the belts. Chambers 380A and 380B are held at a lower pressure than the outside of the system thus creating a pressure differential across the belts. This in turn creates a downflow of air through openings 215, retaining the media object 140 upon the belts.

[0057] Figure 3B shows a similar arrangement for the cross-section B-B' shown in Figure 2. In Figure 3B, first belt 220B is mounted upon axles 255 and 260 and is configured to transport a media object 140 towards aperture 240B in the conveyance direction 190. Second belt section 230B, is mounted upon axles 265 and 275 and is configured to transport the media object 140 further in the conveyance direction 190 after aperture 240B to media output means 130. Above aperture 240B is mounted fluid deposition head 310B which is configured to apply fluid to a passing media object. Any excess fluid ejected from the head 3108 flows across the gap between the head and aperture 240B, into aperture 240B and thus is transported via channel 330B into fluid receptacle 250.

[0058] As in Figure 3A, vacuum chambers 385A and 385B act to retain the media object 140 upon the first and second belts 220B and 230B. A vacuum is also applied to channels 330A and 330B in order to prevent movement of the media object 140 in the Z direction as it passes over respective apertures 240A and 240B. The application of a vacuum to channels 330A and 330B also provides an additional force to direct excess fluid into the fluid receptacle 250.

[0059] Figures 2, 3A and 3B show an exemplary conveyance system that can increase the control of a media object 140 on a conveyance path 120 and can prevent the media object 140 from moving in the Z direction as well as within the X-Y plane. As is shown in Figures 3A and Figures 3B, the typical clearance between the fluid deposition heads 310 and the apertures 240 is small, i.e. in the order of 10 to 20 millimetres, and so any movement in the Z direction of the media object 140 would prevent fluid from being correctly deposited on the object. By tightly clustering first and second belts 220 and 230 around apertures 240, excess fluid may be drained away from the surface of the conveyance path 120 while still retaining the media object on the path using the vacuum retention system. If, as shown in Figure 2, the media object extends across a plurality of conveyance path subsections A, B, C then belts 220A and 220C, neighbouring aperture 240B, help to prevent the edges of the media object 140 extending beyond the X-Y plane in the Z direction while passing over aperture 240B and likewise belt 230B, terminating adjacent to the end of apertures 240A and 240C, retains the centre of the media object in the Z direction whilst said object passes over apertures 240A and 240C.

[0060] Figure 4A shows an exemplary second embodiment of the present invention. This embodiment is similar to the embodiment shown in Figures 2, 3A and 3B; however, in the present case, there are six conveyance path subsections. These comprise a first set of conveyance path subsections 430A, 430B and 430C. These path subsections are separated by a second set of conveyance path subsection which comprises paths 440A, 440B and 440C. The conveyance path subsections of the first set comprise elongate apertures aligned along axis 420 in the direction orthogonal to the conveyance direction. The second set of conveyance paths 440 have elongate apertures aligned along a second axis 425 which is offset from the first axis 420 in the direction of conveyance 190.

[0061] The first set of conveyance path subsections 430 have a first belt subsection mounted upon an axle 265 and a second set of belt mounted upon axle 270. The second set of conveyance path 440 have a first belt mounted upon axle 260 and a second belt mounted upon axle 270. Apertures on conveyance path subsections 440A, 430B, 440B and 430C are surrounded on all sides by conveyance mechanisms in the form of driven belts to minimise the effect of any areas where the media object is not driven. This arrangement also distributes the active driving components across the direction orthogonal to the conveyance direction.

[0062] Figure 4B shows a side view of the second embodiment 400. Above chassis 450 is mounted a deposition device supporting structure 460 in which a plurality of fluid deposition devices 410 are mounted. Figure 4C shows the second embodiment in plan view with the deposition devices 40 mounted above the conveyance system 400. Supporting structure 460 secures six fluid deposition devices 410A to 410F, wherein each fluid deposition device 410 is mounted opposite a corresponding aperture in the conveyance path below. Hence, any fluid ejected from a fluid deposition device that is not deposited on a media object 140 will pass through a respective aperture below the device into a fluid receptacle.

[0063] Figure 5A shows a component of an exemplary third embodiment of the present invention. The third embodiment uses a number of supporting plates 550 that sit within each aperture 240 to provide support for a passing media object 140. Figure 5A also shows a channel structure 520 that extends from aperture 240 to a fluid receptacle below, in a similar manner to channels 330 shown in Figure 3A and 3B. Channel structure 520A is attached to two lower flanges 510A, 510B that have a number of fastening apertures 515A to 515D for fastening the channel structure 520 to a fluid receptacle such as receptacle 250 shown in Figures 3A and 3B. In use, the lower flanges 510 are fixed to a fluid receptacle via fastening devices such as screws that are threaded through apertures 515A.

[0064] The supporting plate 550 (sometimes referred to as a "skip plate") typically comprises a polymer structure, a portion of which is configured to fit inside aperture 240. In the present case, supporting plate 550 comprises two flanges 555A and 555B that, in use, respectively extend away from a central aperture or apertures 560 in the direction of neighbouring conveyance mechanisms such as belts 220, 230. Aperture(s) 560 communicate with elongate aperture 240. In the example shown in Figure 5A, the supporting plate 500 comprises four apertures 560, however any number of apertures may be provided with a single aperture being preferred to reduce the deposition of fluid on aperture rims.

[0065] In the present example, supporting plate 550 mates with channel structure 520 using elastically deformable members 570. In use, these members 570 may deform inwardly to allow the members to be fitted inside the channel structure 520. Tabs upon the end of the members mate with corresponding apertures or indentations 525A and 525B in the channel wall 520 to fix the plate in place. Corresponding apertures 520A and 520B are also located on the opposite channel face. The supporting plate 550 may be subsequently removed by depressing the tabs on the end of the members 570 and freeing said tabs from the apertures 525A and 525B. The supporting plate 550 may then be raised vertically away from elongate aperture 240.

[0066] The purpose of the supporting plate 550 is to support the media object 140, as it passes beneath a fluid deposition device and above an elongate aperture and to hold the media object flat via the application of a vacuum provided by retention system 170. The supporting plate also facilitates the removal of fluid, such as an aerosol varnish, from the area around the fluid deposition heads, by providing the airflow pattern shown by the arrows in Figure 5B.

[0067] Figure 5B shows the supporting plate in situ within elongate aperture 240A, i.e. in place within the system as first shown in Figures 2 and 3A. Aperture 240A sits between belts 220A and 230A and is in communication with fluid retention device 250. Neighbouring belt section 230B and axle 265 are also visible, as are vacuum chambers 380A and 380B. Supporting plate 550 fits inside aperture 240A and flanges 555 extend to support a media object along the conveyance path as belts fall 220A and 230A away from the X-Y plane due to their rotation around axle 265 and 270.

[0068] Figure 5B also shows the air flow provided by the vacuum system: air is drawn over the flanges 555 of supporting plate 550, in through aperture(s) 560, and down through aperture 240A into the fluid retention device 250. Such an air flow helps to control the position of a media object and removes excess fluid, such as excess liquid and aerosol varnish, to reduce the build-up of said fluid on belts 220A, 230A and 250B. Supporting plate 550 may be made from a variety of hard-wearing plastics including, but not limited to, sintered glass-loaded nylon.

[0069] Figures 5A and 5B show a locking mechanism in the form of laterally deformable members 570; however, other locking mechanisms may also be used to mount the supporting plate 550 within aperture 240 and channel 330, for example frictional mounts may be used, wherein frictional forces between sections of the plate and channel structure 520 retain the plate within the aperture. The supporting plates can be removed for cleaning and replacement without disturbing the manifold structure below. The channel structure 520 and fluid receptacle may be made from a variety of materials including, but not limited to, stainless steel. Typically, each channel structure 520 and the fluid receptacle are permanently fitted to the chassis of the fluid deposition system.

[0070] Figure 5C shows the system of Figure 3B with supporting plate 550 in place. As can be seen in this Figure, a media object 440 moving along the conveyance path in direction 190 will first be supported by the first belt 220B; then by the flanges of the skip plate 550; then, after moving across the skip plate 550, the second belt section 230B.

[0071] Figure 5D shows the apparatus of Figure 5B with a fluid deposition device 310A in place. As can be seen, the clearance between the fluid deposition device 310A and the supporting plate 550 is of the order of 2 to 10 millimetres. The locations of aperture 240A and supporting plate 550 are configured to complement the position of the print head 310A.

[0072] Figures 6A, 6B and 7 show a fourth embodiment of the present invention. Figure 6A shows a perspective view of a removable conveyance system 600 that may be removably mounted within chassis 210 or 450 in place of the components shown in Figure 2 or Figure 4A. As with the previous embodiments, the conveyance system 600 of Figure 6A comprises a number of conveyance mechanisms in the form of driven belts 620n and a number of elongate apertures 640n. The conveyance system 600 is adapted to be fitted into place in a fluid deposition system and thus allow media to pass over the system 600 in conveyance direction 680. The conveyance system 600 is formed as a complete unit and comprises a supporting structure 610 and a single driven axle 630.

[0073] Optional idle guide rollers 650A and 650B are also provided to guide a media object over the apertures 640n; hence, in use, a media object passes underneath rollers 650A and 650B which freely rotate with the passage of the object to provide a downward force and thus to prevent movement of the media object in the Z direction.

[0074] The conveyance system 600 comprises a plurality of odd 660n and even 670n conveyance path subsections. Each conveyance path subsection 660n and 670n comprises a single elongate aperture 640n and a single conveyance mechanism 620n. The apertures in each even conveyance path subsection 660n are offset from those in a neighbouring odd conveyance path subsection 670n. Therefore, as in the other embodiments, the apertures 640n have a staggered arrangement in the conveyance direction, i.e. are relatively offset in a direction orthogonal to the conveyance direction. The example shown in Figure 6A comprises five even conveyance path subsections and five odd conveyance path subsections; however, the number of each type of conveyance path subsections may be altered depending on requirements.

[0075] Figure 6B shows the conveyance system 600 mounted in situ as part of the conveyance path 120. In use, a set of one or more rollers 690A convey the media objection 140 towards the conveyance system 600. The leading edge of the media object is driven under first idle roller 650A and over the apertures forming part of the even conveyance path subsections 660n by the conveyance mechanisms of the odd conveyance path subsections. The leading edge of the media object then continues over the conveyance system 600, being subsequently transported over the apertures of the odd conveyance path subsections 670n by the conveyance mechanisms of the even conveyance path subsections 660n. Finally, the media object passes under the second idle roller 650B onto one or more downstream conveyance mechanisms 690B, which continue the path of the media object in the conveyance direction 190. In use, fluid deposition devices may be mounted above the conveyance system 600 so that each individual fluid deposition device is mounted opposite a corresponding aperture 640n.

[0076] Figure 7 shows the components of an exemplary even conveyance path subsection 660n. The odd conveyance path subsections 670n have similar components arranged in a complimentary manner. As with the previous embodiments, the aperture 640 is formed in the top of a channel structure 520 which in turn is connected to a fluid receptacle 250. A supporting plate 550 such as that described with the third embodiment may be mounted within aperture 640; however, the use of a supporting plate is optional. Each conveyance mechanism forming part of the conveyance path subsections comprises a belt 620 rotatably mounted upon a vacuum chamber 710 and a driven axle 630. The driven axle 630 is located below the vacuum chamber 710. This configuration enables a vacuum to be applied to the complete area of belt 620 and thus provide a continuous retention force as the media object passes over the conveyance system 600. As with the previous embodiments, a vacuum may also be applied to one of channel structure 520 or receptacle 250 to apply a vacuum as the media object passes over the aperture 240 and supporting plate 550.

[0077] The fourth embodiment has the further advantage that a vacuum or other retention force can be applied across the whole path of the media object's passage underneath the fluid deposition device. In the first through third embodiments, it was not possible to supply a vacuum force in the vicinity of the drive axles either side of each aperture. As can be seen in Figures 3A, 3B and 5C, vacuum chambers 385A and 385B need to terminate before axles 260, 265 or 275. This means that, between the end of each vacuum chamber 380 or 385 and the beginning of the aperture 240, no vacuum force is applied and the media object may rise up or curl in the Z direction. In the fourth embodiment, as a vacuum is applied continuously via the vacuum chamber 710 as the media object traverses the conveyance system 600, curling is reduced and conveyance is improved. This is possible due to the location of the drive axle 630 below the pressure chamber 710.

[0078] The embodiment of Figure 7 also provides a further advantage in that only a single axle 630 is required to drive the conveyance mechanisms that convey the media object underneath the fluid deposition devices. Hence, as seen in Figure 6A, the end of axle 630 may be integrated into a drive system comprising a motor and gearing system (not shown) to drive the complete unit 600.

[0079] The conveyance mechanism of Figure 7 also comprises an optional tensioning device that may be provided to maintain the tension of belt 620. The tensioning device comprises an idle, i.e. freely rotating, roller 720 mounted on axle 730 within tensioning frame 725. Roller 720 provides a tensioning force to the belt 620 and thus maintains adequate traction and rotation. Typically, tensioning frame 725 is attached to the fluid receptacle 250 by way of support structure 735 as shown in Figure 7.

[0080] Each vacuum chamber 710 may be connected to one or more neighbouring vacuum chambers via connecting element 715. This enables a single pump system to reduce the pressure across all vacuum chambers 710 within the conveyance system 600.

[0081] Belt 620 may be a one millimetre vacuum permeable belt with a nominal length of 140 millimetres. The corners of the vacuum chamber around which the belt is rotatably mounted may be of a 5 millimetre diameter. The vacuum chamber may be formed of stainless steel and the drive roller may be of 20 millimetres in diameter.

[0082] The conveyance system of any of the first to fourth embodiments enables a recording media object such as a sheet of paper, to be transported through a fluid deposition area at a required traverse speed wherein the media object is suitably supported, positionally controlled and retained up to and around a fluid jetting area. A combination of vacuum forces and applied physical pressure enable the media object to be retained upon a conveyance path and maintain positioning outside direct fluid application areas. The system of the present invention also further enables jetting height and jetting accuracy for the deposition of fluids to be maintained over areas designed for the collection of waste or erroneous fluid.

[0083] The system may also provide a series of replaceable skip plates which enable the system to avoid conveyance contamination and which enable a suitable airflow pattern to provide deposited fluid and/or to enable fluid deposited beyond the edge of a media object to be removed. The supporting plate geometry also ensures that media edges are transported successfully through the fluid deposition area without catching on any structural objects and also avoids the media object dipping into waste or overspray collection areas.

Claims

1. A conveyance system (200) for use in conveying a media object (140) past a plurality of fluid deposition devices (150, 410) in a predetermined conveyance direction (190), the conveyance system characterised by:

a plurality of elongate apertures (240) for receiving excess fluid from the fluid deposition devices (150, 410), each aperture extending in a direction orthogonal to the conveyance direction (190); and

a plurality of conveyance mechanisms (220, 230) aligned with the plurality of elongate apertures (240) in the conveyance direction (190), each mechanism being adapted to convey at least a portion of a media object (140) in the conveyance direction;

wherein one end of each conveyance mechanism (220, 230) terminates adjacent to a corresponding elongate aperture (240) in the conveyance direction (190) and each elongate aperture (240) terminates adjacent to at least one neighbouring conveyance mechanism (220, 230) in a direction orthogonal to the conveyance direction (190).

2. The conveyance system (200) of claim 1, wherein the elongate apertures (240) are arranged such that:

at least one elongate aperture (240) terminates adjacent to a respective neighbouring conveyance mechanism (220, 230) at each end of the aperture in a direction orthogonal to the conveyance direction (190);

each elongate aperture (240) is relatively offset in the conveyance direction (190) from an immediately neighbouring elongate aperture;

the length of each elongate aperture (240) is substantially equal to the width of each aligned conveyance mechanism (220, 230); or

for each elongate aperture (240), a first conveying mechanism (220) terminates adjacent to a first side and a second conveying mechanism (230) terminates adjacent to a second, opposite, side

3. The conveyance system (200) of any of the preceding claims, wherein the plurality of elongate apertures (240) are in communication with one or more fluid receptacles (250) for receiving excess fluid.

4. The conveyance system (200) of any of the preceding claims further comprising:

a plurality of plates (550) for supporting the media object (140) during conveyance across a respective elongate aperture (240);

each plate (550) comprising:

one or more apertures (560) in communication with the elongate aperture;

one or more flanges (555) that extend away from the elongate aperture (240) in the direction of one or more respective neighbouring conveyance mechanisms (220, 230).

5. The conveyance system (200) of claim 4, wherein each plate (550) further comprises a locking mechanism (570) for removably mounting the plate (550) within a respective aperture (240), the locking mechanism (570) preferably comprising one of:

elastically deformable arms that, in use, mate with the walls of a channel extending from each elongate aperture (240); or

frictional mounts that retain the plate within a channel extending from each elongate aperture (240) using frictional forces.

6. The conveyance system (200) of claim 4 or claim 5, wherein each plate (550) comprises sintered glass-loaded nylon.

7. The conveyance system (200) of any of the preceding claims further comprising a retention system (170) to hold a media object (140) in place during conveyance, preferably a vacuum system that provides a pressure differential along the length of each elongate aperture (240) and within each conveyance mechanism (220, 230).

8. The conveyance system (200) of any of the preceding claims, further comprising:

a plurality of conveyance paths (430, 440) extending in the conveyance direction (190), each path (430, 440) comprising two conveyance mechanisms having respective driven belts (220, 230), a first belt (220) positioned before a respective elongate aperture (240) in the conveyance direction (190) and a second belt (230) positioned after the elongate aperture (240) in the conveyance direction (190);

wherein a first set of conveyance paths (430) comprises one or more elongate apertures (240) extending in a first line (425) in a direction orthogonal to the conveyance direction (190) and a second set of conveyance paths (440) comprises one or more elongate apertures (240) extending in a second line (420) in a direction orthogonal to the conveyance direction (190), the first line (425) and second line (420) being relatively offset from each other in the conveyance direction (190), and the second set of conveyance paths (440) being interleaved with the first set of conveyance paths (430) in a direction orthogonal to the conveyance direction (190).

9. The conveyance system (200) of claim 8, further comprising:

three or more axles (260, 265, 270) extending in a direction orthogonal to the conveyance direction (190);

wherein,
for the first set of conveyance paths (430), a first axle (270) supports each belt (230) that terminates adjacent to a first side of each aperture (240) and a second axle (265) supports each belt (220) that terminates adjacent to a second side of each aperture (240); and
for the second set of conveyance paths (440), the second axle (265) supports each belt (230) that terminates adjacent to a first side of each aperture (240) and a third axle (260) supports each belt (220) that terminates adjacent to a second side of each aperture (240).

10. The conveyance system (200) of any of claims 1 to 7, further comprising:

a plurality of conveyance paths (660n, 670n) of a common predetermined width extending in the conveyance direction (190, 680), each path comprising a conveyance mechanism having a driven belt (220, 620n, 720) and a respective elongate aperture (240, 640n).

11. The conveyance system (200) of claim 10, wherein:

a first set of conveyance paths (660n) has elongate apertures (240, 640n) extending in a first line in a direction orthogonal to the conveyance direction (190, 680), the corresponding conveyance mechanism (220, 620n) being positioned at a first side of said apertures; and

a second set of conveyance paths (670n) has elongate apertures (240, 640n) extending in a second line in a direction orthogonal to the conveyance direction (190, 680), the corresponding conveyance mechanism being positioned at a second side of said apertures, the second set of conveyance paths (670n) being interleaved with the first set of conveyance paths (660n) in a direction orthogonal to the conveyance direction (190, 680),

wherein the first line and second line are relatively offset from each other in the conveyance direction (190, 680).

12. The conveyance system (200) of claim 10 or claim 11, wherein each conveyance mechanism (620n) comprises one or more of:

a vacuum chamber (710) around which the driven belt (720) is rotatably mounted, wherein each vacuum chamber (710) is preferably in communication with the vacuum chamber of at least one neighbouring conveyance mechanism;

a drive axle (630) common to all conveyance mechanisms; and

a tensioning device (740) for maintaining the tension of the drive belt (720).

13. The conveyance system (200) of any of the preceding claims, wherein the fluid is a varnish to be applied to the media object (140).

14. A fluid deposition system (100) for depositing fluid on a media object (140), comprising:

a plurality of fluid deposition devices (410) extending in a direction orthogonal to a conveyance direction (190) of the media object (140); and

the conveyance system (200) of any one of claims 1 to 13;

wherein each elongate aperture (240) within the conveyance system (200) is positioned, preferably less than 20 millimetres, opposite a corresponding fluid deposition device (410).

15. The fluid deposition system (100) of claim 14, wherein the conveyance system (200) is removably mounted as a single unit (600) within the fluid deposition system.

Drawing