Airflow control through self-closing holes in a movable support surface of a printing system and related devices, systems and methods

Abstract

To reduce the appearance of a blur in a final printed media product in a reliable manner while maintaining speeds of printing and transport.SOLUTION: A printing system comprises an ink deposition assembly and a media transport assembly. The ink deposition assembly comprises a printhead arranged to eject a print fluid to a deposition region of the ink deposition assembly. The media transport assembly comprises a vacuum source and a movable support surface. The movable support surface comprises valves having holes through the media support surface. The media transport assembly is configured to hold one or more print media against the movable support surface by vacuum suction communicated from the vacuum source through the valves. The valves are each configured to transition between a closed state, in which the airflow through the hole of the respective valve is prevented, and an open state, in which the airflow through the hole of the respective valve is allowed.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] Aspects of the present disclosure relate generally to inkjet printing, and more particularly to inkjet printing systems having media transport assemblies that utilize vacuum suction to hold and transport print media. Related devices, systems, and methods are also disclosed. [Background technology]

[0002] In some applications, inkjet printing systems use an ink deposition assembly having one or more printheads and a media transport assembly for moving print media (e.g., a substrate such as paper, envelopes, or other substrate suitable for printing with ink) through an ink deposition region (e.g., an area beneath the printheads) of the ink deposition assembly. Inkjet printing systems form printed images on the print media by ejecting ink from the printheads onto the media as the media passes through the deposition region. In some inkjet printing systems, the media transport assembly utilizes vacuum suction to help hold the print media against a movable support surface (e.g., a conveyor belt, a rotating drum, etc.) of a transport device. The vacuum suction to hold the print media against the support surface can be achieved using a vacuum source (e.g., a fan) and a vacuum plenum fluidly coupled to the vacuum source on a side of the movable support surface opposite the side supporting the print media. The vacuum source creates a vacuum within the vacuum plenum, causing vacuum suction through holes in the movable support surface that are fluidly coupled to the vacuum plenum. When the print media is introduced onto the movable support surface, the vacuum suction generates a suction force that holds the print media against the movable support surface. A media transport assembly that utilizes vacuum suction can allow the print media to be held securely in place without slippage while being transported through the ink deposition area beneath the ink deposition assembly, thereby helping to ensure accurate positioning of the print media relative to the print head, and thus a more accurate printed image. Vacuum suction can also allow the print media to be held flat as it passes through the ink deposition area, which not only helps to increase the accuracy of the printed image, but can also help prevent portions of the print media from lifting up and hitting portions of the ink deposition assembly, potentially causing jams or damage.

[0003] One problem that can arise in inkjet printing systems that include media transport assemblies that utilize vacuum suction is unintended image smearing resulting from air currents induced by the vacuum suction. In some systems, such smearing can occur in portions of a printed image near the edges of the print media, particularly near the leading or trailing edges of the print media in the transport direction (sometimes referred to as the process direction). During a print job, print media are spaced apart on the movable support surface as they are transported through the deposition region of the ink deposition assembly. Therefore, portions of the movable support surface between adjacent print media are not covered by any print media. This region between adjacent print media is referred to herein as the inter-media zone. Therefore, adjacent to both the leading and trailing edges of each print media in the inter-media zone, the movable support surface has uncovered holes. Because these holes are uncovered, the vacuum in the vacuum plenum induces air to flow through the uncovered holes. This air current can deflect ink droplets as they travel from the printhead to the substrate, thus causing image smearing.

[0004] A need exists to improve the accuracy of drop placement in inkjet printing systems and reduce the appearance of bleed in the final printed media product. A further need exists to address the problem of bleed in a reliable manner and while maintaining printing and transport speeds in order to provide an efficient inkjet printing system. Summary of the Invention

[0005] Embodiments of the present disclosure may solve one or more of the problems set forth above and / or may demonstrate one or more of the desirable features set forth above. Other features and / or advantages may become apparent from the following description.

[0006] According to at least one embodiment of the present disclosure, a printing system includes an ink deposition assembly and a media transport assembly. The ink deposition assembly includes a print head arranged to eject printing fluid into a deposition region of the ink deposition assembly. The media transport assembly includes a vacuum source and a movable support surface. The movable support surface includes a valve having an aperture through the media support surface. The media transport assembly is configured to hold one or more print media against the movable support surface by vacuum suction communicated from the vacuum source through the valve. Each of the valves is configured to transition between a closed state, in which airflow through the respective valve aperture is prevented, and an open state, in which airflow through the respective valve aperture is permitted.

[0007] According to at least one embodiment of the present disclosure, a movable support surface for a printing system includes a flexible belt and a plurality of valves disposed on the flexible belt to communicate vacuum suction through the flexible belt to hold a print medium being transported by the movable support surface against the flexible belt, the valves being configured to transition between an open state in which vacuum suction is communicated through the respective valve and a closed state in which vacuum suction is blocked through the respective valve.

[0008] According to at least one embodiment of the present disclosure, a method includes placing a print medium on a movable support surface of a media transport assembly of a printing system and holding the print medium against the movable support surface via vacuum suction through valves of the movable support surface. The method further includes transitioning valves covered by the print medium from a closed state in which vacuum suction is blocked through their respective valves to an open state in which vacuum suction is allowed through their respective valves via interaction between the print medium and the valves. The method further includes transporting the print medium in a process direction via the movable support surface through a deposition region of a print head of the printing system and ejecting printing fluid from the print head to deposit the printing fluid on the print medium at the deposition region. [Brief explanation of the drawings]

[0009] The present disclosure can be understood from the following detailed description taken alone or in conjunction with the accompanying drawings, which are included to provide a further understanding of the disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate one or more embodiments of the present teachings and, together with the description, explain certain principles and operations.

[0010] [Figure 1A] 1A-1C illustrate schematic representations of airflow patterns relative to the printhead assembly, transport device, and print media during different stages of print media transport through the ink deposition area of ​​a conventional inkjet printing system, and the resulting bleed effects in the print media product. [Figure 1B] 1A-1C illustrate schematic representations of airflow patterns relative to the printhead assembly, transport device, and print media during different stages of print media transport through the ink deposition area of ​​a conventional inkjet printing system, and the resulting bleed effects in the print media product. [Figure 1C] 1A-1C illustrate schematic representations of airflow patterns relative to the printhead assembly, transport device, and print media during different stages of print media transport through the ink deposition area of ​​a conventional inkjet printing system, and the resulting bleed effects in the print media product. [Figure 1D] 1A-1C illustrate schematic representations of airflow patterns relative to the printhead assembly, transport device, and print media during different stages of print media transport through the ink deposition area of ​​a conventional inkjet printing system, and the resulting bleed effects in the print media product. [Figure 1E] 1A-1C illustrate schematic representations of airflow patterns relative to the printhead assembly, transport device, and print media during different stages of print media transport through the ink deposition area of ​​a conventional inkjet printing system, and the resulting bleed effects in the print media product. [Figure 1F] 1A-1C illustrate schematic representations of airflow patterns relative to the printhead assembly, transport device, and print media during different stages of print media transport through the ink deposition area of ​​a conventional inkjet printing system, and the resulting bleed effects in the print media product. [Figure 1G] 1A-1C illustrate schematic representations of airflow patterns relative to the printhead assembly, transport device, and print media during different stages of print media transport through the ink deposition area of ​​a conventional inkjet printing system, and the resulting bleed effects in the print media product. [Figure 1H] 1A-1C illustrate schematic representations of airflow patterns relative to the printhead assembly, transport device, and print media during different stages of print media transport through the ink deposition area of ​​a conventional inkjet printing system, and the resulting bleed effects in the print media product. [Figure 1I] 1A-1C illustrate schematic representations of airflow patterns relative to the printhead assembly, transport device, and print media during different stages of print media transport through the ink deposition area of ​​a conventional inkjet printing system, and the resulting bleed effects in the print media product. [Figure 1J] 1A-1C illustrate schematic representations of airflow patterns relative to the printhead assembly, transport device, and print media during different stages of print media transport through the ink deposition area of ​​a conventional inkjet printing system, and the resulting bleed effects in the print media product. [Figure 1K] 1A-1C illustrate schematic representations of airflow patterns relative to the printhead assembly, transport device, and print media during different stages of print media transport through the ink deposition area of ​​a conventional inkjet printing system, and the resulting bleed effects in the print media product. [Figure 1L] 1A-1C illustrate schematic representations of airflow patterns relative to the printhead assembly, transport device, and print media during different stages of print media transport through the ink deposition area of ​​a conventional inkjet printing system, and the resulting bleed effects in the print media product.

[0011] [Figure 2] 1 includes a block diagram illustrating components of an embodiment of an inkjet printing system including an air flow control system.

[0012] [Figure 3]FIG. 2 is a schematic diagram of an ink deposition assembly and a media transport assembly of an embodiment of an inkjet printing system.

[0013] [Figure 4] FIG. 10 is a plan view from above of an embodiment of a movable support surface having a valve.

[0014] [Figure 5A] 5 is a cross-sectional view of the movable support surface of FIG. 4, the cross-section being taken along A in FIG. 4; [Figure 5B] 5 is a cross-sectional view of the movable support surface of FIG. 4, the cross-section being taken along A in FIG. 4; DETAILED DESCRIPTION OF THE INVENTION

[0015] In the drawings and descriptions herein, a numerical index such as “_1,” “_2,” etc., is added after the reference number of some components. When there are multiple similar components and it is desired to refer to a specific one of those components, the same reference number is used, with a different index added to distinguish between the individual components. However, when components are referred to generally or collectively without the need to distinguish between specific ones, the index may be omitted from the reference number. Thus, as an example, as in FIG. 1A , when it is desired to identify a specific one of the print media 5, the print medium 5 may be labeled and referred to as first print medium 5_1, but in other cases where it is not desired to distinguish between multiple print media 5, it may be labeled and referred to simply as print medium 5.

[0016] As mentioned above, when the inter-media zone is near or below the print head, uncovered holes in the inter-media zone can create cross-flow that can blow satellite drops off course and cause image smear. Similarly, uncovered holes along the inboard or outboard side of the print media can also create cross-flow that causes image smear. To better explain some of the phenomena that create smear problems, reference is made to Figures 1A-1F. Figures 1A, 1D, 1G, and 1J schematically illustrate a print head 10 printing on a print media 5 near the trailing edge TE, leading edge LE, inboard edge, and center of the print media 5, respectively. Figures 1A, 1D, and 1J are cross sections taken through a print head 10 along the process direction (y-axis direction in the figures), while Figure 1G is a cross section taken through the same print head 10 along a cross-process direction perpendicular to the process direction (x-axis direction in the figures). The view in Figure 1G shows an embodiment with three print heads in series along the x-direction, one offset from the other two. Figures 1B, 1E, 1H, and 1K show enlarged views of regions A, B, C, and D of Figures 1A, AD, 1B, and 1J, respectively. Figures 1C, 1F, 1I, and 1L show enlarged photographs of printed images, including printed lines at the trailing edge TE, leading edge LE, inboard edge, and near the center of the paper, respectively.

[0017] As shown in FIGS. 1A, 1D, 1G, and 1J, an inkjet printing system includes one or more print heads 10 for ejecting ink onto a print medium 5 through print head openings 19 in a carrier plate 11. The inkjet printing system also includes a movable support surface 20 for transporting the print medium 5 in a process direction P, which corresponds to the positive y-axis direction in the figures. The movable support surface 20 slides along the top of a vacuum platen 26, and a vacuum environment is provided on the bottom side of the platen 26. The movable support surface 20 has holes 21, and the vacuum platen 26 has platen holes 27. The holes 21 and 27 periodically align as the movable support surface 20 moves, thereby exposing the area above the movable support surface 20 to the vacuum below the platen 26. In areas where the print medium 5 covers the holes 21, vacuum suction through the aligned holes 21 and 27 generates a force that holds the print medium 5 against the movable support surface 20. However, because these covered holes 21 and 27 are blocked by the print medium 5, little or no air is drawn into the covered holes 21 and 27 from the environment above the movable support surface 20. On the other hand, as shown in FIGS. 1A, 1D, and 1G, in the inter-media zone 22 (see FIGS. 1A and 1D) and the uncovered region 24 near the inboard side IB of the platen 26 (see FIG. 1G), the holes 21 and 27 are not covered by the print medium 5, and therefore the vacuum suction pulls air from above the movable support surface 20 to flow downward through these holes 21 and 27. This creates an airflow, indicated by the dashed arrows in FIGS. 1A, 1D, and 1G, in the inter-media zone 22 and the uncovered region 24, from the area around the print head 10 toward the uncovered holes 21 and 27, with a portion of the airflow passing underneath the print head 10.

[0018] In FIG. 1A , the print medium 5_1 is printed near its trailing edge TE, and therefore the region where ink is currently being ejected (the “ink ejection region”) (e.g., region A in FIG. 1A ) is located downstream of the inter-media zone 22 (upstream and downstream are defined with respect to the process direction P). Thus, some of the air drawn toward the inter-media zone 22 flows upstream through the ink ejection region below the print head 10. More specifically, vacuum suction from the inter-media zone 22 reduces the pressure in the region immediately above the inter-media zone 22, e.g., region R1 in FIG. 1A , while the region downstream of the print head 10, e.g., region R2 in FIG. 1A , remains at a higher pressure. This pressure gradient causes air to flow upstream from region R2 toward region R1, with the air flow crossing the portion of the ink ejection region (e.g., region A in FIG. 1A ) that lies between regions R1 and R2. These air flows across the ink ejection region are referred to herein as cross-flows 15. In FIG. 1A, the cross flow 15 is flowing upstream, but in other situations the cross flow 15 may flow in a different direction.

[0019] As shown in enlarged view A' of FIG. 1B, which includes an enlarged view of region A of FIG. 1A, main drops 12 and satellite drops 13 are formed as ink is ejected from print head 10 toward media 5. Satellite drops 13 are much smaller than main drops 12, resulting in less mass and momentum; therefore, upstream cross-flow 15 tends to affect satellite drops 13 more than main drops 12. Thus, while main drops 12 may land on print media 5 near their intended deposition locations 16 regardless of cross-flow 15, cross-flow 15 may push satellite drops 13 from their intended trajectories, causing them to land at unintended locations 17 on media 5, displaced from unintended locations 16. The results of such cross-flow and resulting misplaced droplets can be seen in the actual printed image of FIG. 1C , where the denser region of printed dots 16′ corresponding to the intended printed line is formed primarily by droplets deposited in their intended locations (e.g., generally main droplets 12), while the sparser region of dots 17′ dispersed away from the line is formed by droplets blown away from their intended locations and landing in unintended locations (e.g., generally satellite droplets 13). The resulting image has a smeared or smeared appearance to the printed line. Notably, the smearing in FIG. 1C is asymmetrically biased toward the trailing edge TE, which would be an expected result of the cross-flow 15 near the trailing edge TE blowing primarily in an upstream direction. The inter-media zone 22 may also direct other airflows, such as downstream airflows, from the upstream side of the print head 10 that flow in other directions; however, these other airflows do not pass through the area where ink is currently being ejected in the illustrated scenario and therefore do not contribute to the smearing of the image. Only those air flows that cross the ink ejection area are referred to herein as cross flows.

[0020] 1D-1F schematically illustrate another situation in which such bleeding occurs, this time near the leading edge LE of the print medium 5_2. The causes of bleeding near the leading edge LE are similar to those described above in connection with the trailing edge TE, except that when printing near the leading edge LE, the ink ejection region is now located upstream of the inter-media zone 22. As a result, the cross flow 15 across the ink ejection region now originates from the upstream side of the print head 10, for example, in region R3, and flows downstream to region R4. Thus, as shown in enlarged view B' of FIG. 1E, which includes an enlarged view of region B of FIG. 1D, when printing near the leading edge LE of the print medium 5_2, satellite drops 13 tend to be propelled downstream (in the positive y-axis direction) toward the leading edge LE of the print medium 5_2 and land at unintended locations 17, while main drops 12 tend to land at or near intended locations 16. As shown in FIG. 1F, such an effect results in asymmetric bleeding that is biased toward the leading edge LE of the print medium (i.e., a denser region 16' of print dots corresponding to the line is formed with a sparser region 17' of print dots away from the line toward the leading edge LE).

[0021] 1G-1I show yet another situation in which such bleed can occur, this time near the inboard edge IE of the print medium 5 due to uncovered holes 21, 27 in that region. When printing near the inboard edge IE, the cause of bleed near the inboard edge IE is similar to that described above in connection with the trailing edge TE and leading edge LE, except that the ink ejection region is now located outboard of the uncovered region 24 of holes 21 and 27 in the movable support surface 20 and platen 26. As a result, the cross flow 15 across the ink ejection region now originates from the outboard side of the printhead 10, for example, from region R5, and flows inboard toward region R6. Thus, as shown in enlarged view C' of Figure 1H, which includes an enlarged view of region C of Figure 1G, when printing near the inboard edge IE, satellite drops 13 are sprayed inboard (in the positive y-axis direction) toward the inboard edge IE of the print medium 5, landing at unintended locations 17 rather than at intended locations 16 where main drops 12 land. As shown in Figure 1I, such a cross flow pattern is expected to result in asymmetric bleeding biased toward the inboard edge IE (i.e., a denser region 16' of printed dots corresponding to the line is formed with a sparser region 17' of printed dots away from the line toward the inboard edge IE).

[0022] In contrast, as shown in FIG. 1J and enlarged view D' of FIG. 1K, which corresponds to an enlargement of region D in FIG. 1J, enlarged view D' of FIG. 1K shows that when printing farther from the edge (rear, front, or inboard) of the print medium 105, there may be little or no airflow 15 because the inter-media zone 22 and uncovered area 24 are too far away to induce airflow that far. Because cross-flow 15 is nonexistent or weak away from the edge of the print medium 5, satellite drops 13 in this region are likely to stray and be blown off course. Thus, as shown in FIGS. 1K and 1L, when printing farther from the edge of the print medium 5, satellite drops land at their intended locations 16 or at locations 18 much closer to their intended locations 16, resulting in less image bleed. Although the satellite drop deposition locations 18 may vary slightly from the intended locations 16 due to other factors affecting the satellite drops 13, the deviation is smaller than near the leading or trailing edges. Figure 1L shows a resulting image of a situation like Figures 1J and 1K, which shows a printed line exhibiting drops landing at intended locations 16', with some drops landing sufficiently close to intended locations 16' at locations 18'. The resulting image does not show any significantly noticeable bleeding or smearing of the line.

[0023] Embodiments disclosed herein can inhibit a portion of the cross-flow to, among other things, reduce possible resulting image smear. By inhibiting the cross-flow, droplets (including, for example, satellite droplets) ejected from the print head are closer to or more likely to land at their intended deposition locations. According to various embodiments, the airflow control system includes several valves disposed on the movable support surface, each forming a closable hole or passageway that communicates vacuum suction through the movable support surface. Each valve is disposed to open or close a corresponding hole based on whether print media is positioned above the valve. The valves are biased to close the hole when not covered by the print media and, conversely, to open the hole when covered by the print media. For example, in some embodiments, the valves can each include a biased closing mechanism (e.g., a flexible reed) movable between an open position that does not block airflow through the hole and a closed position that blocks airflow through the hole. The valve is configured to bias the closure mechanism toward the closed position (e.g., by vacuum suction and / or spring force within the closure mechanism) such that the bias moves the closure mechanism to the closed position when the print medium is not positioned above the valve. The valve is further configured such that, when the print medium is positioned above the valve, the closure mechanism is held in the open position by interaction with the print medium. In particular, vacuum suction through the holes pulls the print medium downward against the reed, pressing the reed toward the open position and overcoming the biasing force biasing the reed to the closed position. In this manner, the movable support surface is configured to automatically block suction through any uncovered holes by the valve being passively actuated to a desired state (e.g., by a biasing element and by interaction of the vacuum suction with the print medium) without the need for active control or an electrically actuated actuator. Blocking suction through the uncovered holes reduces or eliminates cross-flow induced by such uncovered holes.Cross flow near the trailing, leading and / or lateral edges (outboard and / or inboard edges) of the print medium is reduced or eliminated, and ink droplets (including satellite droplets) are more likely to land at or near their intended deposition locations, thus reducing the amount of bleeding near those edges of the print medium.

[0024] Referring now to Figure 2, an embodiment of a printing system will be described in more detail. Figure 2 is a block diagram that schematically illustrates a printing system 100 that utilizes the airflow control system described above. Printing system 100 includes an ink deposition assembly 101 for depositing ink on print media, a media transport assembly 103 for transporting the print media through ink deposition assembly 101, and a control system 130 for controlling operation of printing system 100.

[0025] The ink deposition assembly 101 includes one or more printhead modules 102. For simplicity, one printhead module 102 is shown in FIG. 2 , but any number of printhead modules 102 may be included in the ink deposition assembly 101. In some embodiments, each printhead module 102 may correspond to a particular ink color, such as cyan, magenta, yellow, and black. Each printhead module 102 includes one or more printheads 110 configured to eject printing fluid, such as ink, onto a print medium to form an image. For simplicity, one printhead 110 is shown in FIG. 2 in the printhead module 102, but any number of printheads 110 may be included per printhead module 102. The printhead module 102 may include one or more walls, including a bottom wall, which may be referred to herein as a carrier plate 111. The carrier plate 111 includes a printhead opening 119 through which the printhead 110 is disposed to eject ink. In some embodiments, the carrier plate 111 supports the printheads 110. In other embodiments, the print head 110 is supported by other structures. The print head module 102 may also include additional structures and devices to support and facilitate operation of the print head 110, such as ink supply lines, ink reservoirs, electrical connections, etc., as known in the art.

[0026] As shown in FIG. 2 , media transport assembly 103 includes movable support surface 120, vacuum plenum 125, vacuum source 128, and media loading / registration device 155. Movable support surface 120 transports print media through the deposition region of ink deposition assembly 101. Vacuum plenum 125 provides vacuum suction from vacuum source 128 to one side (e.g., the bottom side) of movable support surface 120, and print media is supported on the opposite side (e.g., the top side) of movable support surface 120. Valves 122 in movable support surface 120 include holes 121 that allow vacuum suction to be communicated through surface 120 when the corresponding valve is in an open state. Vacuum suction communicated through holes 121 can press the print media down against surface 120. Media loading / registration device 155 loads print media onto movable support surface 120 and aligns the print media with various registration datums.

[0027] The movable support surface 120 is movable relative to the ink deposition assembly 101, such that as the movable support surface 120 moves, the print medium held against the movable support surface 120 is transported relative to the ink deposition assembly 101. Specifically, the movable support surface 120 transports the print medium through a deposition region of the ink deposition assembly 101, which is an area where a printing fluid (e.g., ink) is ejected onto the print medium, such as an area beneath the print head 110. The movable support surface 120 can be actuated to move relative to the ink deposition assembly 101 and can comprise any structure having holes 121 that allow vacuum suction to press down on the print medium, such as a belt, drum, or the like.

[0028] As described above, the movable support surface includes valves 122, each of which includes a hole 121. The holes 121 provide passageways through the movable support surface 120 that can fluidly couple an area below the movable support surface 120 to an area above the movable support surface 120. The holes 121 can be opened and closed through a closure mechanism of the corresponding valve 122. The valves 122 are configured to transition between an open state and a closed state based on whether the area is covered by a print medium. When a valve 122 is open, vacuum suction is communicated to the area above the movable support surface through the associated hole 121, while when the valve is closed, airflow through the hole 121 is blocked and vacuum suction is not communicated to the area above the movable support surface through the hole 121. When the hole 121 is not covered by a print medium, each valve 122 is biased to a closed state. On the other hand, when the print medium is positioned over a hole 121, the associated valve 122 is held in an open state, allowing airflow through the hole 121 (and thus communicating vacuum from plenum 125 through hole 121). Valves 122 positioned below the print medium are held in an open state by interaction with the print medium. In some embodiments, all of the valves 122 are initialized to an open state by an externally applied force, for example, via contact with the print medium and / or rollers (shown further below relative to the embodiment of FIG. 3) positioned above the valves 122; then, those valves 122 that are covered by the print medium are held open by interaction with the print medium positioned above them, while those valves 122 that are not covered by the print medium transition back to a closed state due to the biasing force.

[0029] Because each of the valves 122 is biased to a closed state when print media is not positioned over the respective valve 122, suction is automatically blocked through any holes 121 that do not happen to be covered by print media. Blocking suction through uncovered holes 121 reduces or eliminates cross-flow induced by such uncovered holes 121. Thus, image bleed near the edges of the print media is reduced.

[0030] Vacuum plenum 125 comprises baffles, walls, or any other structure arranged to surround or define an environment in which a vacuum (e.g., low-pressure) is maintained by vacuum source 128, and plenum 125 fluidly couples vacuum source 128 to movable support surface 120 such that movable support surface 120 is exposed to the vacuum within vacuum plenum 125. In some embodiments, movable support surface 120 is supported by vacuum platen 126, which may be the top wall of vacuum plenum 125. In such embodiments, movable support surface 120 is fluidly coupled to the vacuum in plenum 125 via platen holes 127 through vacuum platen 126. In some embodiments, movable support surface 120 is itself one of the walls of vacuum plenum 125 and is therefore directly exposed to the vacuum in plenum 125. Vacuum source 128 may be any device configured to remove air from plenum 125 to create a low-pressure condition in plenum 125, such as a fan, pump, etc.

[0031] As described above and as is well known to those skilled in the art, the media loading / registration device 155 loads print media onto the movable support surface 120 and registers the print media with respect to various registration datums. For example, each print media may be loaded onto the movable support surface 120, with one edge of each print media registered (i.e., aligned) with a process direction registration datum (e.g., registration datum Reg in FIG. 1G ) extending in the process direction. Herein, the side of the media transport assembly 103 closest to the process direction registration datum is referred to as the outboard side of the media transport assembly 103, the edge registered to this datum is referred to as the outboard edge, the opposite side of the device is referred to as the inboard side, and the opposite edge is referred to as the inboard edge. In practice, registration datums can be located on both sides of the media transport assembly 103, and therefore the side of the media transport assembly 103 that is considered the outboard side will vary from system to system (or from time to time within the same system) as the print media is accidentally registered. Additionally, the leading edge and / or trailing edge of the print media can be aligned with various cross-process datums along the movable support surface 120 as the print media is loaded thereon. Thus, by aligning each print media with one of the process direction alignment datum and the cross-process alignment datum, precise location and orientation of the print media relative to the movable support surface 120 can be achieved, enabling accurate printing of an image on the print media. Various media loading devices for loading and aligning the print media relative to the movable support surface are known in the art and are used in existing printing systems. Any existing media loading device or any new media loading device can be used as the media loading / alignment device 155. Because the structure and function of such media alignment devices are well known in the art, further detailed descriptions of such systems will be omitted.

[0032] The control system 130 includes processing circuitry for controlling the operation of the printing system 100. The processing circuitry may include one or more electronic circuits configured with logic for performing the various operations described herein. The electronic circuitry may include logic for performing the operations by including software instructions that perform the various operations executable by the circuitry, or by including dedicated hardware configured to perform the various operations, or any combination thereof. In examples where the logic includes software instructions, the electronic circuitry of the processing circuitry includes a memory device that stores the software and a processor that includes one or more processing devices capable of executing instructions, such as, for example, a processor, processor core, central processing unit (CPU), controller, microcontroller, system-on-chip (SoC), digital signal processor (DSP), graphics processing unit (GPU), etc. In examples where the logic of the processing circuitry comprises dedicated hardware, in addition to or instead of a processor, the dedicated hardware may include any electronic device configured to perform specific operations, such as an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA), a Complex Programmable Logic Device (CPLD), a discrete logic circuit, a hardware accelerator, a hardware encoder, etc. The processing circuitry may also include any combination of dedicated hardware and general-purpose hardware with software.

[0033] Referring now to Figure 3, an embodiment of a printing system 300 is described that may be used as printing system 100 described above with reference to Figure 2. Figure 3 includes a schematic diagram showing a portion of printing system 300 from a side view. As shown in Figure 3, printing system 300 includes an ink deposition assembly 301 and a media transport assembly 303, which may be used as ink deposition assembly 101 and media transport assembly 103, respectively. Printing system 300 may also include additional components not shown in Figure 3, such as a control system (e.g., control system 130).

[0034] In printing system 300, ink deposition assembly 301 includes four printhead modules 302 as shown in FIG. 3, each printhead module 302 having a plurality of printheads 310. The printhead modules 302 are arranged in series along a process direction P above a media transport assembly 303 such that a print medium 305 is transported sequentially beneath each of the printhead modules 302. The printheads 310 are arranged to eject printing fluid (e.g., ink) through corresponding printhead openings 319 in corresponding carrier plates 311. In one embodiment, each printhead module 302 has three printheads 310, arranged in an offset pattern where two printheads 310 are aligned within each other in the cross-process direction and the third printhead 310 is offset upstream or downstream from the other two printheads 310. (In FIG. 3 , one of the printheads 310 is obscured by another printhead 310, so only two printheads 310 per module 302 are visible in this view.) In other embodiments, different numbers and / or arrangements of printheads 310 and / or printhead modules 302 are used.

[0035] In printing system 300, media transport assembly 303 includes a flexible belt that provides movable support surface 320. As shown in FIG. 3 , movable support surface 320 is driven by rollers 329 to move along a looped path, a portion of which passes through ink deposition region 323 of ink deposition assembly 301. Additionally, rollers 356 may be provided to press print media against movable support surface 320, thereby facilitating flat adhesion of print media 305 to movable support surface 320. Further, in this embodiment, vacuum plenum 325 includes a vacuum platen 326 that forms a top wall of plenum 325 and supports movable support surface 320. Platen 326 includes platen holes 327 that allow fluid communication between the interior of plenum 325 and the underside of movable support surface 320.

[0036] The movable support surface 320 includes several valves 322 that can be used as the valves 122 in the printing system 100 of FIG. 2 . Each of the valves 322 includes a hole 321 for fluidly coupling an area below the movable support surface 320 to an area above the movable support surface, and a closure mechanism for opening and closing the hole 321. Thus, the valves 322 and their respective holes 321 have an open state and a closed state. The holes 321 are arranged such that the outlet opening of each hole 321 (e.g., on the bottom side of the movable support surface 320 opposite the side that supports the print medium) is aligned in the process direction (y-axis) with a corresponding collection of platen holes 327. Thus, as the movable support surface 320 moves across the platen 326, each hole 321 periodically moves over a corresponding platen hole 327, resulting in the holes 321 and platen holes 327 being temporarily aligned vertically (i.e., aligned in the z-axis direction). When a hole 321 is in an open state and moves over a corresponding platen hole 327, the hole 321 and platen hole 327 fluidly couple the environment above the movable support surface 320 to the low pressure condition in the vacuum plenum 325, thus defining an open passageway that creates a vacuum suction through the hole 321 and platen hole 327. This suction creates a vacuum hold-down force on the print media 305 placed above the hole 321. When a hole 321 is in a closed state, vacuum suction is prevented from being communicated through the hole 321, regardless of whether the hole 321 is aligned with the platen hole 327.

[0037] Valves 322, similar to valve 122 described above, are configured to transition between an open state and a closed state based on whether they are covered by print media. Valves 322 are initialized to an open state (by an external force, described further below). After being initialized to an open state, a biasing force causes valves 322 to automatically transition from an open state to a closed state when not covered by print media 305, as described further below. Meanwhile, those valves 322 that are covered by print media are held open by interaction with the print media, which overcomes the biasing force.

[0038] More specifically, the valve 322 may include a closure mechanism (e.g., a flexible reed) movable between an open position and a closed position, the position of which controls whether the hole 321 in the valve 322 is open or closed. The closure mechanism is biased toward the closed position. The biasing force biasing the closure mechanism to the closed position may include a vacuum suction force applied to the closure mechanism as a result of the closure mechanism being exposed to vacuum suction from the plenum 325. The biasing force may also include an internal structural force (e.g., a spring force) of the closure mechanism. When no print media is present above a given valve 322, the closure mechanism is moved to the closed position because there is no counterforce to overcome the biasing force. On the other hand, when print media is present above a given valve 322, the print media interacts with (e.g., presses against) the closure mechanism, providing a counterforce to overcome the biasing force and hold the closure mechanism in the open position. The opposing force from the print medium can include the weight of the print medium 305 along with a vacuum suction force applied to the print medium 305 through the open holes 321 .

[0039] In some embodiments, the initialization of the valves 322 to the open state may occur as a result of the weight of the print media pressing against the closing mechanism as the print media is placed on the movable support surface 320. In such embodiments, only the valves 322 that happen to be located below the print media may be initialized to the open state, while the other valves may remain in the closed state.

[0040] However, in some embodiments, the weight of the print medium 305 alone may be insufficient to overcome the biasing force to move the closure mechanism to the open position. Therefore, in some embodiments, rollers 356 (see FIG. 3 ) are used to provide an additional external force to help initialize the valve to the open position. When the movable support surface 320 (and the print medium resting thereon) passes under rollers 356, rollers 356 press against the movable support surface 320 (either directly or through the print medium, if present), thereby applying a force to the closure mechanism of the valve 322. The force generated by rollers 356 pressing against the closure mechanism is sufficient to overcome the biasing force, and thus the closure mechanism is moved to the open position as the valve passes rollers 356. Once a given valve 322 is initialized to the open position, it will either remain in the open position or transition to the closed position based on whether print medium 305 is present over hole 321, as described above. Valves 322 located below the print media remain open even after the pressing force from rollers 356 is no longer present, even though the weight of the print media is insufficient to overcome the biasing force. Because holes 321 were initially opened by rollers 356, vacuum suction from the vacuum plenum can now be communicated through open holes 321 to the print media above valves 321, and the vacuum suction interacts with the print media to create a suction force that pulls the print media against the movable support surface. This suction force on the print media (combined with the print media's weight) is sufficient to overcome the biasing force and hold the valves in the open position. Thus, immediately after passing rollers 356, all valves 322 are open, but shortly thereafter, all holes 321 covered by the print media remain in the open state, while all holes 321 not covered by the print media transition to the closed state 321.

[0041] The valves 322 automatically move to a closed state when no print media 305 covers the holes 321 associated with the valves 322, thereby preventing cross-flow that would otherwise be induced through those holes 321. Thus, image bleed near the edges of the print media 305 is reduced or prevented. Additionally, because the holes 321 covered by the print media 305 are in an open state, vacuum suction can be communicated through those holes 321 and the print media 305.

[0042] 3, the platen hole 327 may include (be coupled to) a channel on its upper side, which may increase the opening area of ​​the platen hole 327 on its upper side. Specifically, the platen hole 327 may include a through-hole portion 327a that opens to the bottom side of the platen 326 and a channel portion 327b that opens to the top side of the platen 326, with the channel portion 327b extending in the process direction. In some embodiments, multiple through-hole portions 327a may be coupled to the same channel portion 327b.

[0043] The media transport assembly 303 also includes a media loading / alignment device 355 that loads the print media 305 onto the movable support surface 320 and aligns the print media 305 with respect to the movable support surface 320. The media loading / alignment device 355 is similar to the media loading / alignment device 155 described above and can be used as the media loading / alignment device 155 described above. In some embodiments, the roller 356 can be part of the media loading / alignment device 355.

[0044] 4-5B illustrate embodiments of a valve that can be used with a movable support surface according to various embodiments of the present disclosure. FIG. 4 is a detailed perspective view of the valve 422 from above the valve 422. FIGS. 5A and 5B include cross sections taken along line A in FIG. 4, with FIG. 5A showing the valve 422 in a closed state and FIG. 5B showing the valve 422 in an open state. In some embodiments, such as FIG. 4, the valve 422 is formed in the movable support surface 420, with a portion of the valve 442 formed by the material of the movable support surface 420. In other embodiments (not shown), the valve 442 can be formed as a separate structure that can be joined to the movable support surface 420. In FIGS. 4-5B and the following description, the various layers 428-432 are illustrated and described as separate layers for ease of understanding. However, in practice, the layers 428-432 may be joined together or fabricated together as a unitary whole, such that they may be indistinguishable from one another in the final product. In other words, in some embodiments, the valve 422 is formed from separately identifiable layers, which may include layers 428-432, while in other embodiments, the valve 422 may be formed in a material without identifiable layers, in which case the layers 428-432 described herein should be understood to refer to different portions (e.g., depths) of the material. In some embodiments, the layers 428-432 are also part of the movable support surface 420. For convenience, some of the following description will assume that the layers 428-432 are part of the movable support surface 420, but this is not limiting. In FIG. 4, the top layer 428 of the valve 422 (which in some embodiments may also be the top layer of the movable support surface 420) is transparent to allow visibility of the other portions.

[0045] 4-5B, the valve 422 includes a hole 421 through the movable support surface 420 on which the valve 422 is mounted, forming a passageway therethrough. The hole 421 includes a top hole portion 435 defining a passageway that opens to the top side (the side facing the print medium) of the movable support surface 420, and a bottom hole portion 427 offset from the top hole portion 435 defining a passageway that opens to the bottom side (the side facing the vacuum platen / vacuum plenum) of the movable support surface 420. The top hole portion 435 may be formed in layers 428 and 429, and the bottom hole portion 427 is formed in layers 430-432. The hole also includes a chamber 434 formed in layers 430 and 431, with the top hole portion 435 fluidly coupled to the chamber 434 (assuming that the lead 423, described in more detail below, is in the open position). Bore 421 also includes one or more channels 426 formed in layer 429 that are fluidly coupled at one end to bottom bore portion 427 and at the other end to chamber 434 (again, assuming lead 423 is in the open position). Top bore portion 435 is therefore fluidly coupled to bottom bore portion 427 via chamber 434 and channels 426 (again, assuming lead 423 is in the open position), and thus bore 421 can fluidly couple the area below valve 422 to the area above valve 422.

[0046] As noted above, in Figure 4, top layer 428 has been omitted / made transparent to reveal features below top layer 428. Top layer 428 covers each of the portions shown in Figure 4 except for the area corresponding to top hole portion 435, and top layer 428 has an aperture that forms part of top hole portion 435. In Figure 4, bottom hole portion 427 is offset from top hole portion 435 in the process direction (y-direction), and thus channel 426 extends in the process direction, although in other embodiments valve 422 and / or hole 421 may be oriented in any manner.

[0047] As described above, the valve 422 also includes a flexible lead 423 positioned in the chamber 434 below the upper hole portion 435. The lead 423 forms a closure mechanism of the valve 422 and is movable between a closed position (see FIG. 5A ) and an open position (see FIG. 5B ). In the closed position, the lead 423 is positioned at the boundary between the upper hole portion 435 and the chamber 434, and thus the lead 423 blocks airflow between the chamber 434 and the upper hole portion 435. Additionally, in the closed position, the lead 423 is positioned at the boundary between the chamber 434 and the channel 426, and thus the lead 423 blocks airflow between the chamber 434 and the channel 426. Thus, in the closed position of the lead 423, the hole 421 is closed, and airflow is prevented between the upper hole portion 435 and the bottom hole portion 427. In the open position (see FIGS. 4 and 5B), the reed 423 allows airflow between the top hole portion 435 and the chamber 434, and between the chamber 434 and the channel 426. Thus, in the open position of the reed 423, the hole 421 is open, allowing airflow between the top hole portion 435 and the bottom hole portion 427. The airflow is indicated by dashed arrows in the figures, and several portions of the airflow are labeled 450a-450d, which are discussed further below.

[0048] The leads 423 may be formed from the material of the movable support surface 420 itself, such as from a flexible belt material, in various embodiments, or may alternatively be separate structures. The proximal end of the leads 423 is connected to the remainder of the valve 422, and the distal end of the leads 423 is a free end that can move perpendicularly to the remainder of the valve 422 (i.e., along the thickness dimension of the movable support surface 420). The leads 423 are therefore configured as cantilevers such that a downward force applied to the distal end of the leads 423 causes the leads 423 to resiliently flex / bend. In the closed position (see FIG. 5A ), the leads 423 are relatively unbent and are generally parallel to the top and bottom surfaces of the third layer 430 of the movable support surface 420. In the open position (see FIG. 5B ), the leads 423 are bent such that their distal ends move downward toward the bottom side of the movable support surface 420. Reed 423 includes a protrusion 424 at its distal end portion. Protrusion 424 extends perpendicularly from the remainder of reed 423, such that when reed 423 is in the closed position, protrusion 424 extends from upper hole portion 435, and the top of protrusion 424 is located above the top of layer 428 (i.e., the top of movable support surface 420). Thus, when print medium 405 is present above valve 422 (see FIG. 5B ), protrusion 424 is contacted by the bottom surface of print medium 405. If print medium 405 is pressed flat against top surface 428 (i.e., the top surface of movable support surface 420), for example, by a roller or by vacuum suction, then the force exerted by print medium 405 on protrusion 424 pushes protrusion 424 downward, moving reed 423 to the open position. When the print medium is not present (see FIG. 4A), the reed 423 can then return to the closed position. In some embodiments, the reed 423 is integrally formed from the material of the layer 430 (e.g., from the material of the movable support surface 420), for example, by cutting or otherwise removing material to form the reed 423. In other embodiments, the reed 423 is a separate structure joined to the rest of the valve 422.

[0049] As described above, one or more channels 426 are formed in layer 429. As shown in FIGS. 4-5B, channel 426 is formed as an open space that is omitted or removed from layer 429. Channel 426 is bounded on the upper side by layer 428 and laterally by portions of layer 429. In particular, channel 426 is laterally separated from upper hole portion 435 in second layer 429 by barrier 425 that surrounds upper hole portion 435. In FIG. 4, two channels 426 extend along either side of upper hole portion 435 and run along the lateral portions of barrier 425 that separate channel 426 from upper hole portion 435. The bottom of channel 426 is bounded by lead 423 and / or the remaining portion of third layer 430.

[0050] When the reed 423 is in the closed position ( FIG. 5A ), the top surface of the reed 423 contacts or is very close to the layer 429 (including the barrier 425). Thus, in the closed position of the reed 423, the reed 423 and the layer 429 (including the barrier 425) cooperate to block the channel 426 from the chamber 434, preventing airflow therebetween. Thus, in the closed position of the reed 423, airflow is blocked between the bottom hole portion 427 and the top hole portion 435, and thus, vacuum suction from the vacuum plenum is not communicated to the top hole portion 435. However, in the closed position of the reed 423, vacuum suction from the vacuum plenum is communicated to the channel 426, and thus, a relatively low-pressure condition is established in the channel 426. This relatively low-pressure condition in the channel 426 results in a vacuum suction force F1 being applied to the reed 423, pulling the reed 423 upward. The force F1 is represented by the solid arrow in FIG. 5A . Thus, in the closed state, the vacuum suction from the vacuum plenum creates a force that holds the leads 423 in the closed position.

[0051] When reed 423 is in the open position ( FIGS. 4 and 5B ), the top surface of reed 423 is spaced from the bottom of barrier 425, so that air can flow between chamber 423 and channel 426 by passing under barrier 425 (through the gap between the bottom of barrier 425 and the top of reed 423). Hypothetical air flows are shown by dashed arrows in FIGS. 4 and 5B . For example, air enters hole 421 through top hole portion 435, as shown in FIGS. 4 and 5B , by air flow 450 a, and then passes under barrier 425 into channel 426, as shown by air flow 450 b. Air then flows through channel 426, as shown by air flow 450 c, to bottom hole portion 427, as shown by air flow 405 d, where air exits hole 421. Thus, when reeds 423 are in the open position, vacuum suction from below movable support surface 420 can be communicated to the upper side of movable support surface 420 through holes 421, bottom hole portion 427, channel 426, chamber 434, and top hole portion 435. As shown in FIG. 5B , when print medium 405 is above holes 421, the vacuum suction communicated to the bottom side of print medium 405 through holes 421 creates a relatively low pressure condition below print medium 405, which applies a vacuum suction force F2 to the print medium, pulling it downward. Force F2 is represented by the solid arrow in FIG. 5B . This vacuum suction force F2 tends to pull print medium 405 downward, resulting in print medium 405 being pressed downward against protrusion 424 of reeds 423. The upward spring force of the reeds 423 and the upward vacuum force F1 applied to the reeds 423 tend to resist downward movement of the reeds 423, but the downward vacuum force F2 is large enough to overcome this resistance. The downward vacuum force F2 applied to the print medium 405 may be large enough to overcome the upward vacuum force F1 applied to the reeds 423 due to the geometry of the holes 421. For example, a larger surface area of ​​the print medium 405 is exposed to the vacuum and can generate a larger suction force.Furthermore, the location at which force F2 is applied to reed 423 (i.e., at protrusion 424) may be distal to the location at which force F1 is applied, providing greater leverage (mechanical advantage) for force F2 to be applied to reed 423. Thus, the downward vacuum force F2 applied to print medium 405 overcomes the resistance of the upward suction force and the spring tension of reed 423, resulting in print medium 405 being pulled flush against the top of movable support surface 420 and reed 423 being forced down to the open position. Reed 423 remains in this open position as long as vacuum suction continues to be applied to print medium 405. However, if print medium 405 is removed, the upward vacuum force F1 and the spring tension of reed 423 then move reed 423 back to the closed position.

[0052] Valve 422 may be similar in some ways to a reed valve, which utilizes a flexible reed positioned over an aperture to allow airflow in one direction while preventing airflow in the opposite direction through the aperture. However, valve 422 may differ in various ways. For example, valve 422 allows airflow in one direction while not necessarily intended to prevent airflow in multiple directions, since airflow through valve 422 is already restricted to moving in one direction by vacuum suction during operation. Furthermore, in a reed valve, the reed is generally actuated as a result of which side of the reed is exposed to higher and which to lower pressure (as a result of a change in airflow direction); i.e., when lower pressure is located on the first side of the reed, the reed is open, and when lower pressure is located on the second side of the reed, the reed is closed. In contrast, in valve 422, low pressure is located on the same side of reed 423 in both the closed and open states (assuming vacuum suction is on). Thus, valve 422 is not actuated from closed to open as a result of a change in which side of reed 423 is exposed to lower pressure; rather, valve 422 is actuated from a closed state to an open state as a result of the application of an external force to reed 423 (e.g., from the print media and / or rollers).

[0053] As noted above, in some embodiments, the valve 422 is an integral part of the movable support surface 420, formed at least in part from the material of the movable support surface 420. In some of these embodiments, the movable support surface 420 comprises a flexible belt having multiple layers 428-432 laminated together, with the valve 522 formed within the layers 428-432. The layers are indicated by dashed lines in FIGS. 5A and 5B. In some embodiments, the layers 428-432 are formed separately and then joined together, for example, by adhesive, fusing (e.g., melting), sewing, or any other joining technique. In some embodiments, the layers 428-432 are formed together as a unitary whole, for example, via additive manufacturing (e.g., 3D printing). In some embodiments, some or all of the layers 428-432 are formed from a different material than the other layers 428-432. In some embodiments, some or all of the layers 428-432 are formed from the same material as each other. In some embodiments, the movable support surface 420 may be approximately 35 mm thick, with each of the layers 428-432 being less than 0.1 mm thick. In some embodiments, the leads 423 and the chambers 434 may be approximately 0.8 mm long, which may allow the movable support surface 420 to flex around rollers used in a media transport assembly without damaging the leads 423 or causing other failures. While the layers 428-432 are illustrated and described herein as separate layers for ease of understanding, in practice, the layers 428-432 may be bonded together or manufactured together as a unitary whole, and thus may be indistinguishable from one another in the final product. The above description of examples of suitable materials and dimensions for the valve 422 and layers is also applicable to other embodiments in which the valve 422 is formed as a separate structure from the movable support surface 420 to which it is (or may be) bonded.

[0054] While particular shapes and relative sizes are shown for the various portions of valve 422, these shapes and relative sizes are not limiting. For example, top and bottom bore portions 435 and 427 may be larger or smaller, have different aspect ratios (i.e., more elongated or less elongated), and have different shapes (e.g., square, polygonal, etc.). As another example, lead 423 may be longer, shorter, wider, narrower, or have a different shape (e.g., rectangular, etc.). Furthermore, while two channels 42 are shown, in other embodiments, fewer or more channels 426 may be provided to couple chamber 434 to bottom bore portion 427.

[0055] In the embodiment described above with reference to FIGS. 4-5B , the valve 422 is formed directly within the movable support surface 420 and is an integral part of the movable support surface 420. In other words, at least a portion of the self-closing hole 421 is formed by the same body that constitutes the movable support surface 420 itself; for example, the material of the movable support surface 420 can form the barrier 425 and define the boundaries of the top hole portion 435, the bottom hole portion 427, and the channel 426. Furthermore, in some embodiments, the lead 423 can also be formed from the material of the movable support surface 420, as described above. However, it should be understood that the same valve 423 can be manufactured in a body separate from the movable support surface 420, and the body can then be later joined to the movable support surface 420. In such an embodiment, the same structure as shown in FIGS. 4-5B is used, but the material layer referred to above as the layer of the movable support surface 420 is instead the material layer of the body in which the valve 422 is formed. The body comprising the valve 422 may be inserted into the movable support surface 420 (e.g., through a hole in the movable support surface 452) and attached to the movable support surface via adhesive, fusing, a press fit, a friction fit, etc. In some embodiments, the body comprising the valve 422 is configured similar to a rivet to have a portion that changes shape after being inserted through the movable support surface 420 (e.g., by bending, deforming, expanding, etc.) to secure to the movable support surface 420.

[0056] The present specification and the accompanying drawings illustrating aspects and embodiments of the present invention should not be construed as limiting, and the claims define the protected invention. Various mechanical, compositional, structural, electrical, and operational changes can be made without departing from the spirit and scope of the specification and claims. In some instances, well-known circuits, structures, and techniques have not been shown or described in detail so as not to obscure the invention. Like numbers in two or more figures represent the same or similar elements.

[0057] Furthermore, the terms used herein to describe aspects of the present invention, such as spatial and relational terms, are selected to aid the reader in understanding embodiments of the present invention, but are not intended to limit the present invention. For example, spatial terms such as "beneath," "below," "lower," "above," "upper," "inboard," "outboard," "up," and "down" may be used herein to describe the orientation or spatial relationship of one element or feature relative to another element or feature, as shown in the figures. These spatial terms are used relative to the orientation shown in the figures and are not limited to a particular frame of reference in the real world. Thus, for example, the direction of "up" in a figure does not necessarily correspond to "up" in the world frame of reference (e.g., away from the Earth's surface). Furthermore, when different frames of reference are considered to be shown in the figures, the spatial terms used herein may need to be interpreted differently in the different frames of reference. For example, a direction referred to as "up" with respect to one of the figures may correspond to a direction referred to as "down" with respect to a different frame of reference that is rotated 180 degrees from the frame of reference of the figure. As another example, if a device is rotated 180 degrees in the world frame of reference compared to how it is shown in the figure, an item described herein as "above" or "over" a second item associated with the figure will be "below" or "beneath" the second item with respect to the world frame of reference. Thus, depending on which frame of reference is being considered, different spatial terms can be used to describe the same spatial relationship or direction. Furthermore, the poses of items shown in the figures are chosen for convenience of illustration and description, but in actual implementations, the items may be in different poses.

[0058] The term "process direction" refers to the direction parallel to and pointing in the same direction as the print media moves as it is transported through the deposition area of ​​the ink deposition assembly. Thus, the process direction is parallel to and points in the positive direction of the y-axis in the figures.

[0059] The term "cross-process direction" refers to a direction perpendicular to the process direction and parallel to the movable support surface. At any given point, there are two cross-process directions pointing in opposite directions: the "inboard" cross-process direction and the "outboard" cross-process direction. Thus, given the frame of reference shown in the figures, a cross-process direction is any direction parallel to the x-axis, including directions pointing in either a positive or negative direction along the x-axis. References to the "cross-process direction" herein should be understood as referring generally to any of the cross-process directions, rather than to one specific cross-process direction, unless otherwise indicated by context. Thus, for example, a statement that "the valve is movable in the cross-process direction" means that the valve can move in the inboard direction, the outboard direction, or both.

[0060] The terms "upstream" and "downstream" may refer to a direction parallel to the process direction, with "downstream" referring to a direction facing the same direction as the process direction (i.e., the direction in which the print media is transported through the ink deposition assembly), and "upstream" referring to a direction facing opposite the process direction. In the figures, "upstream" corresponds to the negative y-axis direction, and "downstream" corresponds to the positive y-axis direction. The terms "upstream" and "downstream" may also be used to refer to the relative locations of elements, with an "upstream" element being displaced upstream relative to a reference point, and a "downstream" element being displaced downstream relative to a reference point. In other words, an "upstream" element is closer to the beginning of the path taken by the print media as it is transported through the ink deposition assembly (e.g., where the print media meets the movable support surface) than some other reference element. Conversely, a "downstream" element is closer to the end of the path (e.g., where the print media leaves the support surface) than some other reference element. The point of reference of other elements to which an "upstream" or "downstream" element is compared may be explicitly stated (e.g., "upstream of the print head") or may be inferred from the context.

[0061] The terms "inboard" and "outboard" refer to cross-process directions, with "inboard" referring to one cross-process direction and "outboard" referring to the cross-process direction opposite "inboard." In the figures, "inboard" corresponds to the positive x-axis direction and "outboard" corresponds to the negative x-axis direction. The terms "inboard" and "outboard" also refer to relative locations, with an "inboard" element displaced inboard relative to a reference point and an "outboard" element displaced outboard relative to a reference point. The reference point may be explicitly stated (e.g., "the inboard side of the print head") or inferred from the context.

[0062] The term "vertical" refers to a direction perpendicular to the movable support surface in the deposition region. At any given point, there are two vertical directions pointing in opposite directions: an "upward" direction and a "downward" direction. Thus, considering the reference frame shown in the figure, a vertical direction is any direction parallel to the z-axis, including directions pointing in the positive z-axis direction ("up") or the negative z-axis direction ("down").

[0063] The term "horizontal" refers to a direction parallel to the movable support surface in the deposition region (or tangent to the movable support surface in the deposition region if the movable support surface is not flat in the deposition region). The horizontal direction includes the process direction and the cross-process direction.

[0064] The term "vacuum" has various meanings, ranging from the strict meaning of a space devoid of all matter to the more general meaning of a state of relatively low pressure. As used herein, the term "vacuum" is used in a general sense and should be understood to refer broadly to a state or environment in which air pressure is lower than some reference pressure, such as ambient or atmospheric pressure. The amount by which the pressure of a vacuum environment must be lower than the reference pressure to be considered a "vacuum" is not limiting and can be a small or large amount. Thus, "vacuum" as used herein may include, but is not limited to, states that can be considered a "vacuum" under the stricter sense of the term.

[0065] The term "air" has different meanings in different contexts, ranging from the strict meaning of the Earth's atmosphere (or a mixture of gases whose composition is similar to that of the Earth's atmosphere) to the more general meaning of any gas or mixture of gases. As used herein, the term "air" is used in a general sense and should be understood to refer broadly to any gas or mixture of gases, which may include, but are not limited to, the Earth's atmosphere, any one of the noble gases (e.g., helium, neon, argon, etc.), nitrogen (N2) gas, or any other desired gas or gas mixture.

[0066] Additionally, the singular forms "a," "an," and "the" are intended to include the plural forms unless the context indicates otherwise. Also, the terms "comprises," "comprising," and "includes" specify the presence of stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups. Unless specifically stated otherwise, components described as coupled may be electrically or mechanically coupled, or indirectly coupled through one or more intermediate components. Mathematical and geometric terms are not necessarily intended to be used in accordance with precise definitions unless the context of the description indicates otherwise, even though the terms also have precise definitions, because those skilled in the art will understand, for example, that substantially similar elements that function in a substantially similar manner may readily fall within the scope of the descriptive terms.

[0067] Elements and their associated aspects described in detail with reference to one embodiment may, wherever practical, be included in other embodiments in which they may not be specifically shown or described. For example, if an element is described in detail with reference to one embodiment and not described with reference to a second embodiment, the element may be claimed as being included in the second embodiment.

[0068] It should be understood that the specific examples and embodiments described herein are non-limiting, and modifications to structure, dimensions, materials, and methodology can be made without departing from the scope of the present teachings.

[0069] Other implementations in accordance with the present disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and embodiments be considered as exemplary only, and that the following claims be accorded the fullest breadth and scope thereof under applicable law, including equivalents.

Claims

1. 1. A printing system comprising: an ink deposition assembly including a printhead disposed to eject printing fluid into a deposition area of ​​the ink deposition assembly; a media transport assembly including a vacuum source and a movable support surface, the movable support surface including a valve having a hole therethrough, the media transport assembly configured to hold one or more print media against the movable support surface by vacuum suction communicated from the vacuum source through the valve; each of the valves is configured to transition between a closed state in which airflow through the aperture of the respective valve is prevented and an open state in which airflow through the aperture of the respective valve is permitted; The valves may include, for each of the valves: maintaining each of the valves in the closed state provided that the print medium does not cover the respective valve; provided that each valve is covered by one of the print media, each valve is held open by a force exerted on the respective valve by the print media through contact between the print media and the respective valve, the force being generated by the weight of the print media and a suction force exerted on the print media by the vacuum suction from the vacuum source. The printing system is configured as follows:

2. The printing system of claim 1 , wherein the valve is biased toward the closed state.

3. each of the valves is biased toward the closed state by a biasing force including a combination of an internal spring force and a suction force applied to each of the valves from the vacuum suction, both the spring force and the suction force biasing the valve toward the closed state; 3. The printing system of claim 2, wherein each of the valves is configured such that, in a print medium condition where the print medium covers the respective valve, the biasing force is overcome by the force applied to the respective valve by the print medium.

4. 4. The printing system of claim 3, wherein each of the valves is configured such that the biasing force causes the valve to move to and / or remain in the closed state provided that none of the print media covers the respective valve.

5. 4. The printing system of claim 3, wherein each of the valves includes a flexible reed configured as a cantilever coupled to the movable support surface, the flexible reed movable between an open position in which the flexible reed allows air flow through the aperture of the respective valve and a closed position in which the flexible reed blocks air flow through the aperture of the respective valve.

6. each of the valves is biased to a closed state by an internal spring force generated by a flexible reed of the respective valve and a suction force applied to the flexible reed of the respective valve by the vacuum suction, both the spring force and the suction force biasing the flexible reed of the respective valve toward the closed position; 6. The printing system of claim 5, wherein each of the valves is configured such that vacuum suction from the vacuum source passes through the hole in the respective valve to generate the suction force on the flexible reed.

7. 7. The printing system of claim 6, wherein each of the valves is configured such that, when the respective valve is in the open state and the print medium is not covering the respective valve, the biasing force moves the flexible reed to the closed position, transitioning the respective valve to the closed state.

8. 7. The printing system of claim 6, wherein when the respective valve is in the open state and covered by one of the print media, the force applied to the respective valve by the print media is sufficient to overcome the biasing force and hold the flexible reed in the open position.

9. 1. A printing system comprising:

2. The printing system of claim 1, wherein the media transport assembly further includes a roller disposed to engage the valve as the valve moves past the roller, and wherein engagement of the roller with one of the valves transitions the valve to the open state.

10. the media transport assembly includes a vacuum platen supporting the movable support surface, the vacuum platen including a platen hole communicating the vacuum suction with the movable support surface; The printing system of claim 1 , wherein the movable support surface comprises a belt configured to move over a surface of the vacuum platen.

11. the media transport assembly further includes a roller configured to engage each of the valves and transition each of the valves to an open state as the valves pass the roller; After each of the valves is placed in the open state, When the respective valve is covered by one of the print media, the respective valve is maintained in an open state by a force applied to the respective valve by the print media; or The printing system of claim 1 , configured such that when the print medium is not covering the respective valve, a biasing force applied to the respective valve causes the valve to transition to a closed state.

12. 10. The printing system of claim 1, wherein for each of the valves, the respective valve is configured to be passively actuated from a closed state to an open state by the print medium contacting and applying a force to a movable portion of the respective valve while the print medium covers the respective valve.

13. 1. A movable support surface for a printing system, comprising: a flexible belt; a plurality of valves disposed on the flexible belt for communicating vacuum suction through the flexible belt to hold a print medium being transported by the movable support surface against the flexible belt; the valves are configured to transition between an open state in which the vacuum is communicated through the respective valve and a closed state in which the vacuum is blocked through the respective valve; each of the valves includes a hole and a flexible lead, the flexible lead configured as a cantilever coupled to the flexible belt, the flexible lead movable by bending between an open position in which the flexible lead allows airflow through the hole of the respective valve and a closed position in which the flexible lead blocks airflow through the hole of the respective valve, the open state of the valve corresponding to the open position of the flexible lead and the closed state of the valve corresponding to the closed position of the flexible lead; A movable support surface, wherein each of the valves is configured such that, under conditions in which vacuum suction is applied to an area below the valve, the vacuum suction generates a biasing force on the flexible reed that biases the flexible reed toward the closed position.

14. The movable support surface of claim 13 , wherein each of the valves is configured to bias the flexible reed to the closed position at least in part through a spring force generated by the flexible reed.

15. The movable support surface of claim 13 , wherein the flexible lead includes a protrusion configured to extend above an upper surface of the movable support surface when the flexible lead is in the closed position.

16. 16. The movable support surface of claim 15, wherein for each of the valves, the flexible reed of the respective valve is configured to be passively actuated from a closed position to an open position by the print medium contacting and applying a force to the protrusion of the flexible reed of the respective valve while the print medium covers the respective valve.

17. 1. A method comprising: placing a print medium on a movable support surface of a media transport assembly of a printing system; holding the print medium against the movable support surface via vacuum suction from a vacuum source communicating through a valve in the movable support surface; transitioning the valves covered by the print medium from a closed state in which the vacuum is blocked through the respective valve to an open state in which the vacuum is allowed through the respective valve by an opening force applied to the valve by the print medium; maintaining the valve, covered by the print medium and transitioned to the open state, in the open state by a holding force applied to the valve by the print medium, the holding force being generated by a weight of the print medium and a suction force applied to the print medium by the vacuum suction from the vacuum source; transporting the print medium in a process direction via the movable support surface through a deposition area of ​​a print head of the printing system; ejecting a printing fluid from the print head to deposit the printing fluid onto the print medium at the deposition area.

18. 20. The method of claim 17, wherein transitioning the valves covered by the print medium from the closed state to the open state includes generating the opening force by pressing the print medium against the valve with a roller.

19. transitioning the valves not covered by the print medium from the closed state to the open state via interaction of a roller with the valve; 20. The method of claim 18, further comprising transitioning the valves not covered by the print medium from the open state to the closed state with a biasing force after the interaction with the roller.

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