Aerosol Extraction Device for Inkjet Printing Systems

Abstract

An inkjet printing system includes a printhead disposed above a media transport path, and an aerosol extraction device disposed downstream of the printhead relative to the media transport direction, the aerosol extraction device including an air knife having a knife slot that directs airflow toward the print media, and a suction nozzle disposed upstream of the knife slot that directs the aerosol into a suction channel.

Description

[Technical Field]

[0001] The present invention relates to an aerosol extraction device for inkjet printing systems, such as digital inkjet printers. The present invention has been developed primarily for extracting aerosols and particulates from areas downstream of the print zone in high speed printing systems. [Background technology]

[0002] Inkjet printers using Memjet® technology are commercially available for a variety of print formats, including desktop printers, digital inkjet presses, and wide-format printers. Memjet® printers typically have one or more user-replaceable fixed inkjet printhead cartridges. For example, desktop label printers have a single user-replaceable multi-color printhead cartridge, high-speed label printers have multiple user-replaceable monochrome printhead cartridges aligned along the media advance direction, and wide-format printers have multiple user-replaceable printhead cartridges stacked one on top of the other across the entire wide-format page width.

[0003] U.S. Patent No. 10,076,917, the contents of which are incorporated herein by reference, describes a wide-page commercial printing system with an N x M two-dimensional array of print modules and corresponding maintenance modules. Providing OEM customers with the flexibility to choose printhead size and number in a modular, cost-effective kit format allows broader access to the commercial digital printing market traditionally served by offset printing systems.

[0004] U.S. Patent No. 10,940,702, the contents of which are incorporated herein, describes an integrated inkjet module for a digital inkjet printer. The inkjet module consists of two overlapping print modules with an integrated maintenance module and an integrated aerosol extraction device. The aerosol extraction device is conventional and includes a suction nozzle located downstream of the print zone and close to the media path. The suction nozzle is positioned opposite the direction of media movement and sucks ink aerosol and / or paper dust downstream of the print zone.

[0005] Aerosol extraction is a critical component in high-speed printing systems. Without sufficient aerosol extraction, the printing environment, including downstream print modules, can become contaminated with ink mist. Contamination of downstream print modules with ink mist can cause problems for a variety of reasons. For example, the ink mist can get into downstream print areas, reducing print quality. The ink mist can also condense on printer components, causing condensed droplets to drip onto the print media, reducing print quality. Furthermore, the ink mist can contaminate sensitive electronic components in downstream print modules, potentially causing catastrophic failure of the contaminated print modules.

[0006] Conventional aerosol extraction systems, such as those described in U.S. Patent No. 10,940,702, have several problems. First, the aerosol extractor's suction nozzle must be located close to the media path to extract ink aerosol traveling through the boundary layer associated with the media. Placing the suction nozzle close to the top of the media path is problematic because it increases the risk of media impinging on the aerosol extractor, potentially leading to poor print quality, media jams, and printing system downtime. Second, over extended periods of printing, the suction nozzle can become clogged with dried ink and paper dust, reducing its effectiveness. Reduced aerosol extraction can result in ink mist entering downstream printing modules and the entire printing environment.

[0007] One way to improve aerosol extraction in conventional systems is to increase the suction force at the aerosol extractor suction nozzle, but increasing the suction force has the disadvantages of expediting drying of the inkjet nozzles of the upstream printhead as well as generating excessive airflow in the print zone, resulting in print quality defects.

[0008] It would be desirable to provide an alternative aerosol extraction system for inkjet printing systems that alleviates or ameliorates at least some of the problems associated with conventional aerosol extraction devices. Summary of the Invention

[0009] In a first aspect, an inkjet printing system is provided, comprising: a print head disposed above a media feed path; and an aerosol extraction device disposed downstream of the print head relative to a media feed direction, the aerosol extraction device comprising an air knife having a knife slot that directs an air flow toward a print medium; and a suction nozzle disposed upstream of the knife slot that directs an aerosol into the suction channel.

[0010] Advantageous features of the inkjet printing system according to the first aspect are described below.

[0011] Preferably, the suction nozzle is positioned higher than the knife slot relative to the media feed path, and in one embodiment, the suction nozzle is positioned at a height at least twice the height from the media feed path to the knife slot.

[0012] Preferably, a convex guide surface extends between the upstream side of the knife slot and the downstream side of the suction nozzle. Typically, a curved guide surface interconnects the upstream side of the knife slot and the downstream side of the suction nozzle, the guide surface (convexly) curved from the media feed path towards the suction nozzle.

[0013] Preferably, the height z of the suction nozzle above the knife slot with respect to the distance x from the suction nozzle to the knife slot along the medium supply direction has a relationship of 0.2 < z / x < 2, or preferably 0.5 < z / x < 1.5. Therefore, the guide surface has a relatively gentle curvature, which is configured to induce the Coandă effect on the aerosol flow received at the surface. In some embodiments, z / x is about 1, whereby the guide surface is formed as a quadrant having a radius equal to z and x. Typically, z ranges from 5 to 20 mm or 8 to 15 mm, and x ranges from 5 to 20 mm or 8 to 15 mm.

[0014] Preferably, the distance x from the suction nozzle to the knife slot along the medium supply direction is greater than the stand-off height h of the knife slot above the printing medium.

[0015] Preferably, the tongue portion upstream of the suction nozzle is curved from the medium supply path towards the suction channel.

[0016] Preferably, the aerosol extraction device comprises a housing having a suction chamber connection to the suction port, and the suction channel is connected to the suction chamber.

[0017] Preferably, the suction chamber comprises a groove extending along its length, and the groove is arranged to collect the aerosol deposited on the inner surface of the suction chamber.

[0018] In one embodiment, the suction chamber comprises a drainage surface inclined downwardly towards the groove. In another embodiment, the suction chamber comprises first and second grooves arranged on both sides of the suction channel, and the suction channel extends perpendicularly from the plane of the medium.

[0019] Preferably, the air knife and the suction nozzle are configured so that a first air velocity through the air knife is greater than a second air velocity through the suction nozzle, typically the first air velocity being at least twice the second air velocity.

[0020] Preferably, the suction nozzle is a suction slot that is wider than a knife slot along the media feed direction.

[0021] Preferably, the width of the suction slot is at least 2 mm, at least 3 mm, at least 4 mm, or at least 5 mm (eg, 2 mm to 10 mm or 3 mm to 8 mm).

[0022] Preferably, the width of the knife slot (and / or knife channel) is in the range of 0.2 to 1 mm or 0.3 to 0.8 mm. Typically, the width of the knife slot is about 0.5 mm.

[0023] Preferably, the knife channel terminating in the knife slot has side walls extending generally perpendicular to the plane of the media feed path, such that the air knife directs air generally perpendicular to the plane of the print media.

[0024] In a second aspect, there is provided an aerosol extraction apparatus for an inkjet printing system, the aerosol extraction apparatus comprising: a housing having a vacuum port and an air inlet port; an air knife having a knife slot in fluid communication with the air inlet port and directing an air flow toward a media feed path; a suction chamber in fluid communication with the vacuum port; and a suction nozzle positioned higher than the knife slot relative to the media feed path and directing an aerosol to the suction chamber through a suction channel, wherein curved guide surfaces interconnect each side of the knife slot and the suction nozzle, the guide surfaces curved from the media feed path toward the suction nozzle.

[0025] In a third aspect, a method of extracting aerosol in an inkjet printing system is provided, the method comprising the steps of breaking up aerosol associated with a moving print medium using an air knife that directs a flow of air towards the moving print medium, and extracting the broken up aerosol upstream of the air knife relative to the moving print medium.

[0026] Preferably, the broken aerosol is lifted from the moving print medium and guided around a curved guide surface towards a suction nozzle located upstream of the air knife and at a higher elevation relative to the print medium than the air knife.

[0027] The preferred features of the inkjet printing system described above in relation to the first aspect are, of course, also applicable to the aerosol extraction apparatus and method according to the second and third aspects.

[0028] As used herein, the term "ink" refers to any printing fluid that can be printed from an inkjet printhead. Ink may or may not contain a colorant. Thus, the term "ink" includes traditional dye-based or pigment-based inks, infrared inks, fixatives (e.g., precoats and finishes), 3D printing fluids, sensing inks, solar inks, biological fluids, etc.

[0029] As used herein, the term "air" refers to any gas that is passed through an air knife under pressure. Typically, the gas is blown through the air knife using, for example, a fan or a compressed air source. However, it will be understood that other gases (e.g., nitrogen) may also be used in the air knife.

[0030] In this specification, the term "attached" includes both direct attachment and indirect attachment via an intervening part. [Brief explanation of the drawings]

[0031] An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: [Figure 1] FIG. 1 is a schematic side view of an inkjet printing system according to one embodiment of the present invention. [Figure 2A] FIG. 2A is a simulation showing the airflow near the aerosol extraction device in use. [Figure 2B] FIG. 2B is a simulation showing the aerosol flow near the aerosol extraction device in use. [Figure 3] FIG. 3 is a front view of the aerosol extraction device according to the first embodiment. [Figure 4] FIG. 4 is a side cross-sectional view of the aerosol extraction device according to the first embodiment. [Figure 5] FIG. 5 is a rear view of the aerosol extraction device according to the first embodiment with the rear panel removed. [Figure 6] FIG. 6 is a side cross-sectional view of the aerosol extraction device according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0032] FIG. 1 illustrates a schematic of an inkjet printing system 1 according to one embodiment of the present invention. The inkjet printing system 1 includes an inkjet printhead 2 disposed on a media transport path to print on a print medium 4 (or "media surface 4") transported past the printhead in a media transport direction indicated by arrow M. The printhead 2 is typically a pagewidth printhead configured for high-speed, single-pass inkjet printing. The printhead 2 can use thermal, piezo, or other ink ejection means, and it will be understood that the utility of the aerosol extraction devices described herein is independent of the type of printhead or ink ejection mode.

[0033] As shown in FIG. 1, printhead 2 includes an ink manifold 6 carrying at least one row of print tips 8 for ejecting ink droplets onto a passing medium. For example, printhead 2 may be of the type having a single row of print tips, as described in U.S. Pat. No. 10,589,537 (the contents of which are incorporated herein by reference), or of the type having two rows of print tips, as described in U.S. Pat. No. 10,293,609 (the contents of which are incorporated herein by reference). Furthermore, the printhead may be a single printhead or a modular printhead array, such as either of the modular printhead arrays described in U.S. Pat. No. 10,076,917 or U.S. Pat. No. 10,940,702. These and other types of printheads and printhead arrays will be readily apparent to those skilled in the art.

[0034] The aerosol extraction device 10 is positioned downstream of the printhead 2 relative to the media advance direction M. During high-speed inkjet printing, ink aerosol (or "ink mist") typically becomes entrained in the moving media 4, and, as previously mentioned, some means for extracting this ink aerosol must be incorporated to minimize contamination of the print media (e.g., by condensation or dripping), downstream printhead contamination, or overall printing environment contamination. The aerosol extraction device 10 comprises an air knife 12 having a knife slot 14 for directing an air flow toward the print media 4, and a suction nozzle 16 positioned upstream of the knife slot 14 for directing the aerosol into a suction channel 18.

[0035] The operation of the aerosol extraction device 10 will now be described with reference to Figures 2A and 2B. Figure 2A shows a simulation of the aerosol extraction device 10 and airflow velocities near the print medium during operation. The air knife 12 generates a high-velocity airflow 20, which is directed toward the print medium 4 through the knife slot 14. The knife channel 22 is configured to direct the high-velocity airflow 20 from the knife slot 14 perpendicular to the media surface 4. However, as shown in Figure 2A, the suction force of the suction nozzle 16 inevitably drags the high-velocity airflow 20 upstream (with respect to the media feed direction M) before it strikes the impact zone 24 of the print medium 4.

[0036] In the impact zone 24, where the high-velocity airflow 20 strikes the media surface 4 and causes air vortices 26 to bounce off the media surface, the air knife 12 effectively interrupts the air boundary layer 27 associated with the moving media 4 and deflects it upward toward a curved (convex) guide surface 28. This low-velocity airflow 30 passes around the guide surface 28 and is directed upstream toward the suction nozzle 16. The guide surface 28 connects the upstream side of the knife slot 14 with the downstream side of the suction nozzle 16. The suction nozzle 16 is positioned higher than the knife slot 14 relative to the media surface 4, and the guide surface 28 curves gently upward from the knife slot toward the suction nozzle, away from the media surface.

[0037] Referring to FIG. 2B, a simulation of the aerosol flow resulting from the airflow depicted in FIG. 2A is shown. First, aerosol generated in the upstream print zone (not shown in FIG. 2B) travels along the media feed direction M within a relatively narrow aerosol boundary layer 32 associated with the media surface 4. As the aerosol approaches the impact region 24 of the high-velocity airflow 20, the boundary layer 32 is disrupted, and the disrupted aerosol 34 is lifted from the media surface 4 toward the aerosol-receiving region 35 of the guide surface 28. Due to the well-known Coanda effect, the aerosol follows a curved path around the guide surface 28 toward the suction nozzle 16. As can be seen from FIG. 2B, aerosol extraction is highly effective, with very little aerosol remaining downstream of the aerosol extraction device 10 and no stray aerosol upstream of the suction nozzle 16.

[0038] The efficiency of aerosol extraction can be adjusted by adjusting the first and second air velocities a1 and a2 through the suction nozzle 16 and the knife slot 14, respectively. It will be further understood that the locations of the impingement zone 24 and the aerosol reception zone 35 can be moved upstream or downstream by adjusting the first and second air velocities a1 and a2, as well as the printing speed and standoff height h. The aerosol extraction device 10 is advantageously configured so that, regardless of the locations of the impingement zone 24 and the aerosol reception zone 35, the aerosol is lifted from the media surface 4 and directed around the curved guide surface 28 to the suction nozzle 16. By utilizing the Coanda effect, the guide surface 28 is highly effective in directing the broken-down aerosol to the suction nozzle 16 over a range of air velocities a1 and a2, printing speeds, and standoff heights h. This contrasts with conventional aerosol extraction devices, which must be precisely positioned close to the media feed path (such as within about 1 mm) and have low tolerance for variations in standoff height, printing speed, etc.

[0039] Generally, the second air velocity a2 through the knife slot 14 is greater than the first air velocity a1 through the suction nozzle 16, preferably at least two times greater.

[0040] Preferably, the first and second air velocities a1 and a2 are fixed in the printing system 1 to provide effective aerosol extraction for all, or at least most, common printing speeds used in the printing system (e.g., printing speeds of 0.5 to 5 m / s). For example, the inventors have discovered that for an aerosol extraction device 10 positioned at a standoff height h of 5 mm from the media surface 4, a1 is at least 1 m / s (preferably in the range of 1 to 4 m / s, or 2 to 4 m / s), a2 is at least 5 m / s (preferably in the range of 5 to 15 m / s, or 7.5 to 15 m / s, or 10 to 15 m / s), and a2 > a1, or a2 > 2a1, or a2 > 3a1. For example, when a1 is in the range of 2-4 m / s and a2 is in the range of 10-15 m / s, aerosol extraction was optimized for all print speeds in the range of 0.5-5 m / s, with a standoff height h from the media surface 4 of 5 mm. However, unlike conventional aerosol extraction devices described in the prior art, the standoff height h is not critical to efficient aerosol extraction, and appropriate combinations of first and second air velocities a1 and a2 within a range of standoff height h (e.g., 1-10 mm) can be empirically determined by those skilled in the art without undue experimentation. In some embodiments, the first and second air velocities a1 and a2 can be tailored to a particular printing system or print job to achieve optimal aerosol extraction.

[0041] The novel aerosol extraction device 10 offers several unique advantages over conventional suction extraction devices described in the prior art. First, ink aerosol extraction is more effective than conventional suction aerosol extraction devices. While ink aerosol generated during printing travels along the Couette flow associated with the moving print medium 4, a large portion of this aerosol tends to become trapped in a (generally laminar) boundary layer 32 moving just above the print medium surface, as shown in FIG. 2B. Conventional suction extraction devices are limited in their effectiveness at removing aerosol from this condensed boundary layer 32. However, the high-velocity airflow 20 directed from the air knife 12 toward the print medium 4 is highly effective at separating and stripping the aerosol in this boundary layer 32 from the medium surface, making it more easily removed by suction.

[0042] Second, the knife slot 14 and suction nozzle 16 can be positioned relatively far from the print medium—that is, farther than the printhead-to-paper distance (PPS)—while still maintaining excellent ink aerosol removal performance. Typically, the aerosol extraction device 10 is positioned at a standoff height h of at least 1.5 mm, at least 3 mm, or at least 5 mm from the media surface 4, while typical PPS for thermal inkjet printheads range from 0.5 mm to 2 mm. In contrast, conventional suction extraction devices must be positioned very close (e.g., within about 1 mm) to the moving print medium 4 to apply suction to the aerosol boundary layer 32. However, placing the suction nozzle too close to the moving medium is undesirable because it increases the risk of the medium impinging on the aerosol extraction device. Therefore, an advantage of the present invention is that effective aerosol extraction can be achieved while minimizing the risk of the medium impinging on the aerosol extraction device 10.

[0043] Third, the suction nozzle 16 is shaped as a relatively wide suction slot to collect the broken-down aerosol that flows around the guide surface 28 toward the suction slot. A relatively wide suction slot has the advantage of minimizing the risk of clogging due to dried ink, paper dust, and the like. Typically, the suction slot is at least five times wider than the knife slot. Furthermore, the width of the suction slot is at least 3 mm, at least 4 mm, or at least 5 mm. In contrast, conventional suction extraction devices necessarily have a relatively narrow suction nozzle to provide the suction force required to suck in the aerosol. Therefore, conventional suction extraction devices are prone to clogging, especially during relatively long print runs, due to the potential accumulation of large amounts of ink aerosol and paper dust in the narrow suction nozzle.

[0044] A first aerosol extraction device 10A according to the first embodiment is shown alone in Figures 3 to 5. The same reference numerals are used throughout the figures to denote similar features of each aerosol extraction device 10.

[0045] As shown in FIG. 3, the first aerosol extraction device 10A includes a housing 40 with a suction port 42 for connection to a suitable vacuum source and an intake port 44 for connection to a suitable pressurized air source. A blower fan (not shown) can be connected to the suction port 42 and the intake port 44 to provide the necessary vacuum and pressurized air. In one embodiment, a single blower fan can provide both suction and pressurized air, although the first and second air velocities can be more precisely controlled by using separate blower fans. The air supplied to the intake port 44 can be filtered using a suitable air filter (not shown) known in the art.

[0046] The housing 40 is generally elongated, with a length corresponding to the length of a single-pass printhead (e.g., an A4 or A3 printhead). It will be appreciated that multiple aerosol extractors 10 can be stacked side-by-side or staggered across the media feed path to achieve aerosol extraction in a wide-format printing system. The housing 40 includes a main body 46 that defines suction and air paths for the suction nozzle 16 and air knife 12, respectively. A front plate 48 of the housing 40 is adapted for connection to a print module or other support chassis, as described in U.S. Pat. No. 10,940,702, to provide an integrated printing system with a printhead and aerosol extractor. To maximize the effectiveness of aerosol extraction, the aerosol extractors 10 are preferably positioned downstream of and as close as possible to the corresponding print zone. A back plate 50 fits tightly against the main body 46, fluidly separating the suction and air paths. The back plate 50 is secured to threaded bosses 52 extending across the width of the main body 46 via suitable threaded fasteners (see FIG. 5).

[0047] The housing 40 has a relatively narrow profile along its width, i.e., the direction parallel to the media feed direction M. As such, the aerosol extraction device 10A minimizes the spacing between multiple printheads 2 (e.g., monochrome printheads) in a printing system with multiple printheads aligned in a row along the media feed path. This allows the aligned printheads to be optimally positioned close to each other along the media feed direction M, minimizing alignment issues and optimizing print quality.

[0048] Knife slot 14 is formed in the lowermost surface of housing 40 (by cooperation of body 46 and back plate 50) and extends along its length, i.e., across the media feed path in use. Suction nozzle 16 extends parallel to and coextensive with knife slot 14 as a suction slot adjacent to knife slot 14. As noted above, in use, suction nozzle 16 is located upstream of knife slot 14 in media feed direction M and is positioned higher relative to media surface 4 than knife slot 14.

[0049] As best shown in FIG. 4 , guide surface 28 curves upward from knife slot 14 toward aspirator nozzle 16 and continues along the same curve to define inner wall 54 of suction channel 18. Outer wall 56 of suction channel 18 has a similar curve, which aligns the suction channel with a suction chamber 58 defined by the interior space of housing 40. Suction port 42 is connected to suction chamber 58 and provides suction to aspirator nozzle 16 through suction channel 18. An outer (upstream) tongue 60 of aspirator nozzle 16 curves away from the aspirator nozzle to maximize collection of any stray aerosol.

[0050] Continuing with reference to FIG. 4 , an elongated groove 62 extends longitudinally along the bottom of the suction chamber 58, below the entrance to the suction chamber from the suction channel 18. While most of the aerosol collected in the suction chamber 58 is expelled through the suction port 42, some aerosol may accumulate on the interior surfaces of the suction chamber. These interior surfaces are configured to expel the accumulated aerosol into the groove 62 while minimizing the possibility of the accumulated aerosol flowing back into the suction channel 18. Accordingly, a sloped discharge surface 64 extending downward from the front of the body 46 meets the outer wall 56 of the suction channel 18 at a re-entrant angle, allowing aerosol collected on the discharge surface to flow by gravity toward the groove 62 and drip into it. In this manner, the aerosol extraction device 10A efficiently removes aerosol while minimizing the risk of contaminating the print medium.

[0051] 4 and 5 , the air distribution channel 66 extends parallel to and directly below the groove 62 along the length of the housing 40. The air distribution channel 66 supplies pressurized air to the knife channel 22, which extends perpendicularly from the air distribution channel 66 and terminates at the knife slot 14. The knife channel 22 terminating at the knife slot 14 forms the air knife 12, which is configured to direct air generally perpendicularly toward the media surface 4. While the operation of the aerosol extraction device is relatively tolerant to different knife slot angles (e.g., up to 10 degrees, up to 20 degrees, or up to 30 degrees from perpendicular), it has been found that a knife channel 22 perpendicular to the media surface 4 typically provides optimal aerosol extraction. Therefore, the term “generally perpendicular” (or similar terminology) as used herein with reference to the direction of the high-velocity airflow 20 from the knife channel 22 and / or knife slot 14 is understood to include not only perpendicular, but any angle up to about 30 degrees from perpendicular.

[0052] Pressurized air is supplied to the air distribution channel 66 via an air supply channel 68 which connects the intake port 44 to one end of the air distribution channel. It will be appreciated that the suction chamber 58 is completely fluidly isolated from the air supply channel 68, the air distribution channel 66, and the knife channel 22 by the back plate 50 which fits tightly against the body 46 of the housing 40.

[0053] In some embodiments (not shown), the air distribution channel 66 may be configured (e.g., tapered) to equalize the air pressure along its length and provide a uniform air velocity along the length of the air knife 12.

[0054] 6, a cross-sectional side view of a second aerosol extraction device 10B according to a second embodiment is shown. For clarity, the first aerosol extraction device 10A and the second aerosol extraction device 10B will be collectively or jointly referred to as aerosol extraction device 10.

[0055] The second aerosol extraction device 10B has the same primary functional features as the first aerosol extraction device 10A. Accordingly, the second aerosol extraction device includes an air knife 12 defined by a knife channel 22 terminating in a knife slot 14. Similarly, a suction channel 18 extends from the upstream suction slot 16 toward the suction chamber 58, with each knife slot 14 and suction slot interconnected by a curved guide surface 28. Thus, the second aerosol extraction device 10B functions similarly to the first aerosol extraction device 10A in that the air knife 12 breaks up and lifts the aerosol from the print medium 4, and the broken up aerosol is guided toward the suction slot 16 via the guide surface 28.

[0056] However, in contrast to the first aerosol extraction device 10A, the second aerosol extraction device 10B has a straight suction channel 18 that, in use, extends substantially perpendicularly from the media surface 4 towards the suction chamber 58. Furthermore, the suction chamber 58 comprises a first groove 62A and a second groove 62B disposed on either side of the suction channel 18.

[0057] The first groove 62A and the second groove 62B are configured to receive ink adhering to the inner surface of the suction chamber 58, minimizing the risk of the collected ink re-entering the suction channel 18. From FIG. 6, it can be seen that the suction chamber 58 of the second aerosol extraction device 10B does not have the inclined discharge surface 64 of the first aerosol extraction device 10A. Rather, the inner surface 65 of the second aerosol extraction device 10B is directly connected to the first and second grooves 62A and 62B, eliminating the need for collected ink to drip into the grooves. Therefore, the second aerosol extraction device 10B according to the second embodiment minimizes the possibility of collected ink contaminating the suction channel 18.

[0058] By installing the aerosol extraction device 10 according to the first or second embodiment in a printing system 1 such as the printing system described in U.S. Pat. No. 10,940,702, it is possible to improve aerosol extraction performance while minimizing blockage of the suction channel 18 due to paper dust, dehydrated ink, etc.

[0059] It will, of course, be understood that the invention has been described by way of example only and modifications of detail may be made within the scope of the invention as defined in the appended claims.

Claims

1. 1. An inkjet printing system comprising: a printhead disposed above the media supply path; an aerosol extraction device disposed downstream of the printhead relative to a media feed direction, the aerosol extraction device comprising: an air knife having a knife slot for directing airflow toward the print medium; a suction nozzle positioned upstream of the knife slot to direct the aerosol into a suction channel.

2. 10. The inkjet printing system of claim 1, wherein the suction nozzle is positioned higher than the knife slot relative to the media feed path.

3. 3. The inkjet printing system of claim 2, wherein a convex guide surface extends between the upstream side of the knife slot and the downstream side of the suction nozzle.

4. 4. The inkjet printing system of claim 3, wherein a height z of the suction nozzle above the knife slot relative to a distance x from the suction nozzle to the knife slot along the media feed direction has a relationship of 0.3<z / x<2.

5. 5. The inkjet printing system of claim 4, wherein a distance x from the suction nozzle to the knife slot along the media feed direction is greater than a standoff height h of the knife slot above a print medium.

6. 10. The inkjet printing system of claim 1, wherein an upstream tongue of the suction nozzle curves from the media feed path toward the suction channel.

7. 10. The inkjet printing system of claim 1, wherein the aerosol extraction device comprises a housing having a suction chamber coupling to a suction port, the suction channel coupled to the suction chamber.

8. 8. The inkjet printing system of claim 7, wherein the suction chamber includes a groove extending along its length, the groove positioned to collect aerosol deposited on an interior surface of the suction chamber.

9. 9. The inkjet printing system of claim 8, wherein the suction chamber includes a drainage surface that slopes downwardly toward the groove.

10. 9. The inkjet printing system of claim 8, wherein the suction chamber comprises first and second grooves disposed on opposite sides of the suction channel, the suction channel extending perpendicular to the plane of the media.

11. 10. The inkjet printing system of claim 1, wherein the air knife and the suction nozzle are configured such that a first air velocity through the air knife is greater than a second air velocity through the suction nozzle.

12. 12. The inkjet printing system of claim 11, wherein the first air velocity is at least twice the second air velocity.

13. 10. The inkjet printing system of claim 1, wherein the suction nozzle is a suction slot, the suction slot being wider than the knife slot along the media feed direction.

14. 10. An inkjet printing system, wherein the suction slot has a width of at least 3 mm.

15. 10. The inkjet printing system of claim 1, wherein the knife channel terminating in the knife slot has sidewalls extending generally perpendicular to the plane of the media feed path, thereby causing the air knife to direct air generally perpendicular to the plane of the print media.

16. 1. An aerosol extraction apparatus for an inkjet printing system, the aerosol extraction apparatus comprising: a housing having a vacuum port and an air inlet port; an air knife having a knife slot in fluid communication with the air inlet port to direct airflow toward the media supply path; a suction chamber in fluid communication with the vacuum port; a suction nozzle disposed at a higher position relative to the medium supply path than the knife slot, the suction nozzle directing the aerosol into the suction chamber through a suction channel; Equipped with 1. An aerosol extraction device, comprising: a curved guide surface interconnecting each side of the knife slot and the suction nozzle, the guide surface curving from the media supply path toward the suction nozzle.

17. 17. The aerosol extraction device of claim 16, wherein the width of the suction nozzle is greater than the width of the knife slot.

18. 17. The aerosol extraction device of claim 16, wherein the suction chamber comprises a groove extending along its length, the groove positioned to collect aerosol deposited on an inner surface of the suction chamber.

19. 1. A method for aerosol extraction in an inkjet printing system, comprising: breaking up aerosols associated with the moving print media with an air knife that directs a stream of air toward the moving print media; and extracting the disrupted aerosol upstream of the air knife against a moving print medium.

20. 20. The method of claim 19, wherein the broken aerosol is lifted from the moving print media and guided around a curved guide surface toward a suction nozzle located upstream of the air knife and elevated relative to the print media relative to the air knife.

Images