Printing unit with opposite pivoting inkjet modules

Abstract

A print unit includes a unit chassis and a pair of opposing inkjet modules mounted on the unit chassis, each inkjet module having a respective printhead. The inkjet modules are each pivotally mounted on the unit chassis for pivotal movement toward and away from one another.

Description

[0001] Invention Field This invention relates to a high-speed printing unit. The primary purpose of developing this high-speed printing unit is to minimize the width of the printing area and optimize the print quality of a full-color digital inkjet printer, enabling multiple redundancies for each ink color. Background of the Invention Memjet is available for purchase on the market. ® Page-width inkjet printers are used in many different printing applications, including desktop printers, digital inkjet presses, and wide-format printers. Memjet ® Printers typically include one or more fixed inkjet printheads that are user-replaceable and at least 200 mm in length. For example, a desktop label printer includes a single user-replaceable full-color printhead, a high-speed inkjet printer includes multiple user-replaceable monochrome printheads aligned along the media feed direction, and a wide-format printer includes multiple user-replaceable printheads arranged in an overlapping manner to span the wide-format media feed path.

[0003] Typically, analog printing presses are used for relatively large print runs, where the cost of producing dedicated printing plates is economically feasible. Industrial printing systems are increasingly using single-pass digital inkjet printing for relatively smaller print runs. Digital inkjet printing avoids the high setup costs of producing printing plates and allows for customization of each print job to specific customers. Ideally, the roll-to-roll paper feed system used in existing analog printing systems should be adaptable to allow for the use of "plug-and-play" inkjet modules instead of, for example, offset printing stations. Therefore, it is desirable for the inkjet module to occupy minimal space relative to the media feed direction while allowing for high-speed, full-color printing with optimal print quality.

[0004] Memjet ® The printing technology uses several rows of end-to-end printing chips to construct a page-width printhead, which is ideal for reducing the total span of the printing area along the media feed direction. Each printing chip has five rows of nozzles, which can be used for five-fold redundant printing in a monochrome printhead.

[0005] US 10,857,821 (the contents of which are incorporated herein by reference) describes a printing system with a configurable array of print modules, each print module having a corresponding monochrome printhead configured for single-pass printing. Four print modules can be arranged along a media path for full-color (CMYK) printing, with five redundancies in each color plane. While the system described in US 10,857,821 offers OEMs flexibility in inkjet printer design, as well as high-quality and high-speed printing using five redundancies, the print modules must be aligned and spaced along the media feed path to achieve full-color printing. This places demands on the media feed system, requiring alignment of all colors, thus resulting in relatively high setup costs for OEMs. However, these costs remain significantly lower than alternative page-width printing systems that use overlapping print chips or very large print chips for single-pass printing.

[0006] US 10,293,609 (the contents of which are incorporated herein by reference) describes a full-color page-wide printhead having two rows of mating print chips that receive ink from a common manifold. This printhead achieves double redundancy for each ink color through four rows of active nozzles in each row of print chips.

[0007] The aim is to provide a low-cost printing unit with multiple redundancies for each ink color, which minimizes the span of the printing area along the media feed direction to achieve four-color (CMYK) printing. Furthermore, it is desirable to provide a printing unit that allows access to the printhead for replacement, simplifies printhead alignment and setup procedures, and enables printing with variable printhead-to-paper pitch (PPS) while optimizing print quality. Invention Overview In a first aspect, a printing unit is provided, the printing unit comprising: Unit chassis; A pair of opposing inkjet modules are mounted on the unit chassis, and each inkjet module includes a corresponding printhead. Each inkjet module is pivotally mounted on the unit chassis to allow the inkjet modules to pivotally move toward and away from each other.

[0009] The printing unit according to the first aspect advantageously allows easy access to the printheads and maintenance system in a pair of inkjet modules arranged close together. Furthermore, compared to systems, for example, with sliding traction elements for accessing the printheads, the pivoting movement of the modules enables more repeatable alignment of the printheads.

[0010] In a preferred embodiment, opposing inkjet modules are fully aligned with respect to the media feed direction. In an alternative embodiment, opposing inkjet modules are offset from each other in an overlapping arrangement. For example, two opposing inkjet modules may partially overlap in the media feed path. Alternatively, three inkjet modules may be arranged in a staggered overlapping arrangement, with one inkjet module opposite the other two.

[0011] Preferably, in the clamshell closed configuration, the printing unit is configured for printing, and in the clamshell open configuration, the corresponding front face of each inkjet module is accessible for printhead replacement.

[0012] Preferably, the inkjet modules are positioned with the opposite sides of a common chassis reference block as a reference when in the printing position.

[0013] Preferably, each inkjet module is capable of pivoting independently relative to the unit chassis.

[0014] Preferably, the first inkjet module is mounted in a forward orientation, while the second inkjet module is mounted in a reverse orientation.

[0015] Preferably, each inkjet module includes a module chassis supporting its respective printhead, and each module chassis includes a substrate, wherein a rear wall and an end wall extend upward from the substrate.

[0016] Preferably, each substrate is C-shaped in plan view and has a pair of lateral arms that extend parallel to the media feed direction from opposite ends of a longitudinal base member that extends perpendicular to the media feed direction, and each substrate defines an open longitudinal slot for receiving a corresponding printhead.

[0017] Preferably, the opposing inkjet modules in the forward and reverse orientations have opposing C-shaped substrates, such that the pair of open longitudinal slots are positioned close to each other relative to the pair of longitudinal base members.

[0018] Preferably, each inkjet module includes a cap, which is positioned remotely relative to the pair of printheads.

[0019] Preferably, the unit chassis includes a rectangular frame having a pair of chassis side rods extending parallel to the medium feed direction, and a chassis front rod and a chassis rear rod that interconnect the chassis side rods.

[0020] Preferably, the module chassis is pivotally mounted on a side rod of the chassis about a pivot axis perpendicular to the medium feeding direction.

[0021] Preferably, each chassis side bar has a chassis reference block positioned between the inkjet modules, such that when in a clamshell closed configuration, the corresponding substrates in the inkjet modules are positioned with reference to opposite sides of each chassis reference block.

[0022] In a second aspect, a printing unit is provided, the printing unit comprising: Unit chassis; and A first inkjet module and a second inkjet module are mounted on a unit chassis. Each inkjet module includes a corresponding printhead insert assembly, and each printhead insert assembly includes a replaceable printhead that is receptively fixed within a corresponding insert. Each insert surrounds all sides of its corresponding printhead. The embedding socket for at least the second inkjet module includes: A cantilever spring, which engages with its corresponding printhead, is biased away from the printhead; and A rotary adjuster, which engages with a cantilever spring, is used to push the cantilever spring toward and away from the printhead, so that the tilt of the second printhead of the second inkjet module relative to the first printhead of the first inkjet module can be mechanically adjusted by the rotational movement of the rotary adjuster.

[0023] Preferably, the printheads of the first inkjet module and the second inkjet module are fully aligned with respect to the media feed direction.

[0024] Preferably, the mounting bases for the first inkjet module and the second inkjet module are identical.

[0025] Preferably, each printhead embedding assembly can be removed from its corresponding inkjet module.

[0026] Preferably, the adjustment knob is accessible when the printhead insert assembly is secured in its respective inkjet module.

[0027] Preferably, each insert is fastened to the corresponding printhead carrier of its respective inkjet module.

[0028] Preferably, each insert can be configured in an open position and a closed position, and each insert is only allowed to remove its corresponding printhead from the insert when it is in the open position and only when the printhead insert assembly is removed from the printhead carrier.

[0029] Preferably, each insert includes a pair of longitudinal side rods extending parallel to opposite longitudinal sides of the printhead and a pair of opposite end rods interconnecting the longitudinal side rods to define an insert cavity.

[0030] Preferably, the first longitudinal side rod is fixed, while the second longitudinal side rod can move relative to each other between the open and closed positions.

[0031] Preferably, the cantilever spring is defined at one end of the first longitudinal side rod, and the screw adjuster is received in the threaded opening of the first longitudinal side rod.

[0032] Preferably, the printhead is positioned with reference to the insert via complementary reference surfaces at corresponding opposite ends of the printhead and the insert.

[0033] In a related third aspect, a printhead insert assembly is provided, the printhead insert assembly including a replaceable printhead that is receptively secured within an insert, the insert surrounding all sides of the respective printhead. The embedded base includes: A cantilever spring, which engages with a corresponding printhead, is biased away from the printhead; and A rotary adjuster, which engages with a cantilever spring, is used to push the cantilever spring toward and away from the printhead.

[0034] Preferably, the insert can be configured in an open position and a closed position, and the insert only allows the corresponding printhead to be removed from the insert when it is in the open position.

[0035] Preferably, the insert includes a pair of longitudinal side rods extending parallel to opposite longitudinal sides of the printhead and a pair of opposite end rods interconnecting the longitudinal side rods to define an insert cavity.

[0036] Preferably, the first longitudinal side rod is fixed, while the second longitudinal side rod can move relative to each other between the open and closed positions.

[0037] Preferably, the cantilever spring is defined at one end of the first longitudinal side rod, and the screw adjuster is received in the threaded opening of the first longitudinal side rod.

[0038] Preferably, the printhead is positioned with reference to the insert via complementary reference surfaces at corresponding opposite ends of the printhead and the insert.

[0039] Of course, it should be understood that the preferred embodiments described above in conjunction with the first, second and third aspects are also applicable to any of the first, second and third aspects in relevant circumstances.

[0040] As used herein, the term "inkjet module" refers to a component that includes an inkjet printhead, such as an elongated printhead configured for single-pass printing (referred to in the art as a "page-width" or "line-head" printhead). An inkjet module typically includes one or more of the following components to provide a fully integrated inkjet system: maintenance components, such as caps and / or wipers; mechanisms for moving the printhead and / or maintenance components; ink delivery components, such as pumps, valves, ink connectors, etc.; and electronic circuitry for supplying power and / or data to the printhead.

[0041] 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 colorants. Accordingly, the term "ink" can include conventional dye-based or pigment-based inks, infrared inks, fixatives (e.g., pre-coatings and finishing agents), 3D printing fluids, solar inks, biofluids, sensing fluids, and the like.

[0042] As used herein, the term “installation” includes both direct installation and indirect installation via an interventional component. Attached Figure Description

[0043] Specific embodiments of the invention will now be described by way of example only with reference to the accompanying drawings, in which: Figure 1 It is a 3D view of the printing unit installed on the supporting chassis; Figure 2 It is a 3D view of a single printing unit; Figure 3 It is the bottom of a part of the printing unit; Figure 4 This is a 3D view of the printing unit in the clamshell-open position; Figure 5 This is a top view of the printing unit in the clamshell open position; Figure 6 It is a bottom-view 3D view of the printing unit; Figure 7 It is an enlarged, bottom-view 3D diagram of the suction manifold and printhead; Figure 8 This is a plan view of a portion of the printhead; Figure 9 This is a magnified plan view of the chip bonding area in the printhead; Figure 10 This is a top-down 3D view of the inkjet module when the printhead is in the lowered position. Figure 11 yes Figure 1 The image shows a rear-view perspective view of the inkjet module. Figure 12 This is a top-down 3D view of the inkjet module with the printhead in the raised position. Figure 13 This is a perspective view of a portion of the inkjet module, in which the bracket is shown transparently to expose the sleeve bushing; Figure 14 A portion of the printhead carrier is shown, in which the printhead embedding assembly has been removed; Figure 15 This is a top-down 3D view of the inkjet module, showing the lifting mechanism; Figure 16The inkjet module is shown, with the end walls removed to expose the cap assembly and cover. Figures 17A to 17C This is a side view of the engagement between the cam guide of the cap assembly and the rocker arm of the cap. Figure 18 This is a top-view perspective view of the printhead insert assembly in the closed position. Figure 19 This is a top-view perspective view of the printhead insert assembly in the open position. Figure 20 yes Figure 8 The image shows a bottom-view perspective view of the printhead embedding assembly. Figure 21 This is a 3D view of the printhead being inserted into the insert. Figure 22 The individual insert is shown in the open position; Figure 23 This is a plan view of a portion of the mounting bracket; Figure 24 This is a 3D view of a portion of the modified printhead insert assembly; Figure 25 It is a bottom-view perspective view of a modified printing unit with gap strips; Figure 26 It is a modified top-down perspective view of the printout when it is in a clamshell-like open configuration; Figure 27 This is a side view showing the printing area of ​​the modified printing unit; Figure 28 This is a bottom-view perspective view of a modified printing unit with alternative gap strips containing a polymer film; Figure 29 yes Figure 28 The side view of the modified printing cell shown; and Figure 30 yes Figure 28 The diagram shows a schematic side view of the modified printing unit in the printing position. Detailed Implementation

[0044] Printing unit refer to Figure 1 The image shows a printing unit 200 mounted on a support chassis 202 configured to feed media along the media feed direction. M The feed passes through the printing unit. Printing unit 200 (in...) Figure 2 (Shown separately) It includes a unit chassis 204 and a pair of opposing upstream inkjet modules 1A and downstream inkjet modules 1B, which are mounted in series on the unit chassis with forward and reverse orientations. The individual inkjet module 1 is described in detail below.

[0045] Each inkjet module 1 includes a module chassis 10, which is pivotally mounted on a chassis side rod 205 of a unit chassis 204 about a corresponding pair of module pivots 206 located on opposite sides of the module chassis. Therefore, each inkjet module 1 can be pivotally mounted about a direction perpendicular to the media feed direction. M The pivot axis of the printing unit 200 pivots. The upstream inkjet module 1A and the downstream inkjet module 1B of the printing unit 200 can pivotally move toward and away from each other, so that the printing unit can be configured in a clamshell closed configuration. Figure 1 and Figure 2 ) for printing and in a clamshell-like open configuration ( Figure 4 and Figure 5 This is for printhead replacement and / or maintenance. Each module chassis 10 has an open, corresponding front face that facilitates access to the internal components of each individual inkjet module 1 in a clamshell-open configuration by means of the relative relationship of the inkjet modules in the printing unit (i.e., one inkjet module rotated 180 degrees relative to another inkjet module). Gas struts 208 interconnect each module chassis 10 with chassis side rods 205 to provide a damped eccentric pivoting mechanism for each inkjet module 1.

[0046] exist Figures 1 to 5 In the illustrated embodiment, the upstream inkjet module 1A and the downstream inkjet module 1B are pivotable independently, allowing one or both inkjet modules to pivot. However, those skilled in the art will understand that other pivoting mechanisms can also be employed, thereby mechanically connecting the pair of module chassis 10 such that both inkjet modules must pivot to the clamshell open position. These and other pivoting mechanisms will be readily apparent to those skilled in the art.

[0047] Each individual inkjet module 1 is a fully integrated unit, including a corresponding printhead 3 and a cover and wiper for maintaining the printhead. Each printhead 3 is of the type described in US 10,293,609 (the contents of which are incorporated herein by reference) and includes two rows of print chips 5 mounted on an integral surface of the corresponding ink manifold. Each row of print chips 5 includes multiple print chips mated end-to-end along the length of its corresponding printhead 3. Each inkjet module 1 prints two colors of ink from the two rows of print chips 5 of its corresponding printhead 3. Furthermore, the printheads 3 of this pair of inkjet modules 1, mounted in series on the unit chassis 204, are positioned relative to the media feed direction. M Full alignment enables the print unit 200 to be configured for redundant full-color printing of the four ink colors (CMYK). Redundancy for each color channel is provided by multiple aligned nozzle rows (e.g., 3, 4, or 5 nozzle rows) in each print head 3, which are aligned along the media feed direction. MThe nozzles are perfectly aligned and print the same color ink. Therefore, each set of aligned nozzles can print to the same pixel position during a single pass of printing from the fixed printhead 3, providing redundancy for each color.

[0048] Each inkjet module 1 has a module chassis 10 with an elongated substrate 12 from which a rear wall 14 and a pair of opposing end walls 16 extend upward. Each substrate is C-shaped in plan view and has a pair of lateral arms 18 extending parallel to the media feed direction from opposite ends of a longitudinal base member 20 extending perpendicular to the media feed direction. Therefore, each substrate 12 defines an open longitudinal slot 22 for receiving a corresponding printhead 3. Figure 2 In the middle, the print head 3 rises above the substrate 12 to perform sealing and / or wiping, Figure 6 In the middle, the print head lowers through the slot 22 to perform printing.

[0049] In the printing unit 200, the upstream inkjet module 1A and the downstream inkjet module 1B, respectively oriented in forward and reverse directions, have opposing C-shaped substrates 12, such that the pair of open longitudinal slots 22 are positioned close to each other relative to the pair of longitudinal base members 20. Accordingly, the printheads 3, received by the respective slots 22, are arranged relatively close to each other, thereby making the printing area (in...) Figure 3 The middle is composed of double-headed arrows Z (Indicates) along the medium feed direction M The total span is minimized. For example, in printing unit 200, the printing area contains two printheads 3. Z The span can be less than 20 cm, less than 150 cm, or less than 125 cm.

[0050] refer to Figures 3 to 5 The substrate 12 also serves as a reference plate for each inkjet module 1 through a referenced engagement with a chassis reference block 210 projecting inward from the corresponding chassis side bar 205. Each chassis reference block 210 serves as a common reference for the opposing lateral arms 18 in this pair of substrates 12. The chassis reference block 210 provides a z-reference for each inkjet module 1 and has x Baseline features and y Reference features, used along x shaft and y The axis provides overall reference positioning for the inkjet module. z Fine-tuning of the relative skew of the shaft, as will be explained in further detail below.

[0051] exist Figure 6In the diagram, printing unit 200 is shown in its printing position, with both printheads 3 protruding through corresponding slots 22 of substrate 12. Aerosol extractor 212 is mounted to the rear end rod 207 of unit chassis 204 and is positioned below substrate 12 of downstream inkjet module 1B relative to the media feed direction. M Extending toward the downstream printhead. The aerosol extractor 212 is cantilevered by means of a spring-loaded pivot mount 214 pivotally mounted to the rear end rod 207 and has a free end near the downstream printhead 3.

[0052] The aerosol extractor 212 includes a conduit arm 216, one end of which extends from a vacuum port 218 and the opposite end connects to a suction manifold 220. The conduit arm 216 and the suction manifold 220 have a generally low height profile, with a flat lower surface extending parallel to the plane of the substrate 12. In its rest position, the aerosol extractor 212 is biased against the substrate 12 of the downstream inkjet module 1 and extends parallel to the media feed path to occupy minimal space between the substrate and, for example, an impression plate used to support the printing media.

[0053] The suction manifold 220 extends co-currently with the slot 22 and has multiple suction nozzles 222 for extracting aerosol from the vicinity of the printing area. The suction nozzles 222 are configured to guide the airflow generally along the same direction as the media feed. M The airflow passes through the printing zone in the same direction. Therefore, the aerosol extractor 212 not only removes ink mist but also helps stabilize the vortices associated with the droplets in the printing zone during printing. The substrate 12 of the upstream inkjet module 1A helps to ensure a uniform airflow through the printing zone, which is optimal for stabilizing the vortices associated with the droplets ejected from the printhead 3. The airflow provided by the aerosol extractor 212 can be further optimized, for example, by an optional gap strip having corresponding plates positioned between the printheads 3, to provide a more uniform airflow between the printheads and through the printing zone (see...). Figures 25 to 27 ).

[0054] Printing unit 200 can be configured to print at different jet distances relative to the printing medium (referred to in the art as printhead-to-paper pitch or PPS) by means of adjusting the height of the printhead 3 using a lifting mechanism in each inkjet module 1. Adjusting the height of the printhead 3 typically disrupts optimized airflow through the printing area. However, in printing unit 200, a cantilevered aerosol extractor 212 allows adjustment of the height of the suction nozzles near the downstream printhead. Specifically, now referring to… Figure 7The front tab portion 224 connected to the suction manifold 220 is positioned to abut against the printhead insert 102 supporting the downstream printhead 3. Therefore, when the downstream printhead 3 is lowered, the abutment engagement of the printhead insert 102 with the tab portion 224 causes the suction manifold 220 to pivot against the bias of the pivot mount 218, thereby lowering the height of the suction nozzle 222 to match the height of the printhead 3. When the printhead 3 is raised, the bias of the pivot mount 218 causes the suction manifold 220 to rise with the printhead. In this way, the printing unit 200 is suitable for variable PPS printing with optimized aerosol extraction and optimized airflow through the printing zone.

[0055] Ink cloth tube In one embodiment, the printhead 3 can be configured such that each row of print chips 5 (where each print chip 6 has multiple aligned nozzle rows for redundant printing) receives ink of only one color. Using four rows of print chips 5 on two printheads 3, full-color (CMYK) redundant printing can be achieved using all the nozzle rows in each print chip. In this way, the print unit 200 can mimic a conventional inkjet printer with monochrome inkjet print strips (e.g., the FujiFilmJPress 750S), but with a much narrower print area (and lower cost) than conventional systems.

[0056] However, in order to maximize print quality, Figure 8 and Figure 9 In the alternative embodiment shown, the printing unit 200 can utilize the inherent architecture of each printhead 3, which has two rows of 180-degree rotationally symmetrical print chips 5. As described in US10,293,609, the first row of print chips 5A and the second row of print chips 5B in each printhead 3 include four color channels, so that each individual print chip 6 in a row can be supplied with two colors of ink. Therefore, the two printheads 3 in the printing unit 200 can be considered to have eight color channels (two color channels per row of print chips 5) for printing four different inks (CMYK).

[0057] A fundamental problem prevalent in any page-width printing system with multiple printing chips is the degradation in print quality at the mating areas between the printing chips 6. Inevitably, page-width printheads require some form of compensation to print on the chip mating areas using, for example, electronic splicing techniques, mechanical chip positioning, dedicated chip designs capable of chip mating, or combinations thereof. In Memjet systems with mating chips 6... ®In printhead 3, print quality issues are generally minimized by means of the physical proximity of adjacent chips and a proprietary chip architecture with a "downward-moving nozzle row" (see, for example, US 7,290,852, the contents of which are incorporated herein by reference). Depending on the orientation of print chip 6, the nozzles in the downward-moving nozzle row are delayed or advanced relative to the main nozzle row to provide seamless integration between adjacent print chips. However, in Memjet... ® Print artifacts may still exist in the printhead due to the downward displacement of the nozzle row, especially in certain printing modes, as described in WO2022 / 053258.

[0058] The printing unit 200 has two available color channels for each ink color, allowing the printhead 3 to be configured to mask any printing artifacts caused by the bonding area between adjacent print chips 6. Essentially, ink of each color is allocated to the first color channel of the first row 5A print chips 6 in a forward orientation and to the second color channel of the second row 5B print chips 6 in a reverse orientation (i.e., rotated 180 degrees relative to the first row 5A print chips). In this way, the compensating nozzle group 8A (e.g., the down-shifting nozzle row) in the first row 5A print chips is offset from the compensating nozzle group 8B in the second row 5B print chips. Therefore, any printing artifacts caused by the down-shifting nozzle row 8A in the first row 5A print chips are minimized by the corresponding (i.e., aligned) nozzles from the main nozzle area 7B in the second row 5B. Similarly, any printing artifacts caused by the down-shifting nozzle row 8B in the second row 5B are minimized by the corresponding (i.e., aligned) nozzles from the main nozzle area 7A in the first row 5A print chips.

[0059] exist Figure 9 In the printhead 3 shown, the first row of print chips 5A has two cyan (C) nozzle rows (each with "odd" and "even" sub-rows) and two yellow (Y) nozzle rows. As described in US 10,293,609, the intermediate nozzle row (N) is unused to provide separation between color channels and minimize ink mixing on the nozzle plate. Similarly, the second row of print chips 5B has two cyan (C) nozzle rows and two yellow (Y) nozzle rows. For each color (e.g., cyan), four nozzles are aligned along the media feed direction to provide quadruple redundancy. However, as... Figure 9 As shown, only two cyan dots originate from the downward nozzle row 8A of the first row of print chips 5A; the other two cyan dots originate from the main nozzle row 7B of the second row of print chips 5B. Similarly, the aligned yellow (Y) dots originate from the downward nozzle row 8A of the first row of print chips 5A and the main nozzle row 7B of the second row of print chips 5B.

[0060] Accordingly, it should be understood that the 180-degree rotational symmetry of the first row of print chips 5A and the second row of print chips 5B in the same printhead 3 allows for the concealment or at least minimization of printing artifacts originating from the downward-moving nozzle row 8. This complementary arrangement of the first row of print chips 5A and the second row of print chips 5B in each printhead 3, combined with a suitable ink distribution sequence, advantageously maximizes print quality in the print unit 200 with two printheads. Each printhead 3 receives two colors of ink, but both inks are supplied to the two rows of print chips 5 in the respective printhead.

[0061] Inkjet module For completeness, reference will now be made. Figures 10 to 24 Describes a single inkjet module 1 used in series in the printing system 200.

[0062] like Figure 10 As shown, the inkjet module 1 includes a chassis 10 having an elongated base plate 12 from which a rear wall 14 and a pair of opposing end walls 16 extend upward. In addition to providing structural rigidity to the chassis 10, the rear wall 14 also serves as a support for mounting various fluid components (e.g., clamp valves 15 and pumps 17) and electronic components (e.g., module controller PCB 19) on its front and rear faces. Openings in the rear wall 14 allow for fluid connection from the rear face of the inkjet module 1 without requiring access from above. Openings may also be provided for in-situ access to a rotary adjuster of any printhead insert 102 in the printing unit 200 using a suitable tool (not shown), as will be explained in further detail below.

[0063] The substrate 12 is generally C-shaped in plan view and has a pair of lateral arms 18 that extend from opposite ends of the longitudinal base member 20 along the nominal axis of the inkjet module 1. x Axial extension. An open longitudinal slot 22 defined between the transverse arms 18 extends parallel to the longitudinal axis along the nominal y-axis of the inkjet module 1 and is configured to receive an elongated printhead 3. Therefore, the printhead 3 is asymmetrically positioned in the inkjet module 1 toward its front, such that the printheads are positioned close together in the printing unit 200. The printhead 3 can be lowered through the slot 22 for printing or raised above the substrate 12 for maintenance (e.g., capping and / or wiping).

[0064] A pair of posts 24 extend upward from the transverse arm 18 of the substrate 12 at opposite ends of an open longitudinal slot 22. Each post 24 is anchored to the substrate 12 at its lower end and fixed to a corresponding end wall 16 at its upper end. A pair of brackets 26 are slidably engaged with the posts 24 via corresponding sleeve bushings 28 inserted into each bracket. Each sleeve bushing 28 is slidably movable relative to the corresponding post 24, thereby allowing the brackets 26 to move along the nominal axis of the inkjet module 1.z The axis moves vertically in both directions toward and away from the substrate 12. The flange portion 25 located at the lower end of each sleeve bushing 28 is fastened to each bracket 26, and in the lowered position of the printhead, its corresponding bracket is positioned relative to the substrate 12. Figure 10 ).

[0065] An elongated printhead carrier 30 is fixedly supported between brackets 26 and is linearly slidable with the brackets. The printhead carrier 30 includes a spaced-out front carrier plate and a rear carrier plate 32 that interconnect the brackets 26 and define a cavity 34 therebetween for housing electronic components that supply power and data to the printhead 3. A bracket 38 interconnects the upper portions of the carrier plates 32, and a pair of carrier reference blocks 40 interconnect the lower portions of the carrier plates. The carrier reference blocks 40 are positioned at opposite longitudinal ends of the printhead carrier 30, facing the respective brackets 26. The supported printhead carrier 30, together with the sleeve bushing 28, the post 24, and the chassis 10, provides a robust support structure for the printhead 3. The printhead 3 itself is secured within complementary inserts 102 to form a printhead insert assembly 100, which is mounted to the carrier reference blocks 40 via screw-on fasteners 42 that engage with the inserts.

[0066] The printhead 3 can be positioned at the printing position via a lifting mechanism operably connected to each carriage 26. Figure 10 ) and maintenance location ( Figure 12 The printhead 3 slides linearly towards and away from the substrate 12. The lifting mechanism also allows for adjustment of the printhead 3's height relative to the printing media when in the printing position. Figure 15 As best shown, the lifting mechanism includes a pair of lead screws 44 rotatably mounted to the substrate 12 and extending upward parallel to the post 24. Each lead screw 44 has a corresponding lead nut 46, which are fixedly connected to a corresponding bracket via a lead nut connector 48. The lead screws 44 can be rotated via an interconnected pulley belt assembly 50 operably connected to a common lifting motor 52. Accordingly, the printhead 3 can be raised and lowered by actuation of the lifting motor 52, which simultaneously rotates the lead screws 44 via the pulley belt assembly 50, thereby raising or lowering the printhead carrier 30 connected to the lead nuts 46 via the bracket 26.

[0067] like Figure 12 As best shown, the inkjet module 1 includes a wiper carriage 54 resting at one end of the longitudinal slot 22, the wiper carriage having a microfiber wiping mesh 56. In the printhead raised position, the wiper carriage 54 can be moved longitudinally along the length of the printhead 3 by a wiper moving mechanism 57 mounted on the longitudinal wiper support 55 to wipe away ink and debris from the printhead surface. In the printhead lowered position… Figure 10The wiper carriage 54 in the carriage 26 has a carriage top 27 and a carriage sidewall 29. Therefore, the carriage top 27 and the carriage sidewall 29 provide at least some protection against ink mist and / or debris that may contaminate the wiper carriage 54 via the open front surface of the inkjet module 1 during printing.

[0068] The inkjet module 1 further includes a cap assembly 60 that rests toward the rear wall 14 and can linearly slide toward and away from the printhead 3 along a transverse cap track 62 via a rack and pinion mechanism 64. The cap assembly 60 includes a cap base 66 slidably engaged with the cap track 62, a peripheral printhead cap 68 mounted on the cap base, and cam guides 70 fastened to the cap base at opposite ends of the printhead cap. Figure 12 In the shown stopped (covered) position of the capping assembly, the printhead cap 68 is covered by a cover 72, which is pivotally mounted to the rear wall 14 of the chassis 10. The cover 72 is in the form of a rigid plate that seals the peripheral seal 69 of the printhead cap 68 and maintains a humid environment within the printhead cap when it is not used to cover the printhead 3. A wiper movement mechanism 57 is mounted on a wiper support 55, which is fixedly attached to the rear wall 14, directly above the cover 72.

[0069] When capping the printhead, the capping assembly 60 moves laterally away from the cover 72 to align with the printhead 3, and the printhead is gently lowered onto the printhead cap 68 using a lifting mechanism to reach the capping position. As the printhead rises, the capping assembly 60 moves laterally rearward toward the rear wall 14, causing the cam rear surface 73 of the cam guide 70 to engage with the engagement node 77 of the corresponding rocker arm 74 at each end of the cover. The rocker arm 74 is pivotally mounted to the rear wall 14 and allows the cover 72 to pivot upward as it engages with the cam guide 70, thereby allowing the capping assembly 60 to slide beneath the cover. Once the capping assembly 60 reaches its final resting position, the cover 72 pivots downward back to the covered position by means of the contours of the cam guide 70 and the rocker arm 74, in which the printhead cap 68 is covered by the cover.

[0070] Figure 17A The diagram shows the engagement of the rear cam surface 73 of the cam guide 70 with the engagement node 77 of the rocker arm 74 when the cap assembly 60 approaches the rear wall 14. Figure 17B The image shows the rocker arm 73 pivoting upwards as the capping assembly transitions to its covered position. Figure 17C The capping assembly 60 is shown in its rearmost stopped position, with the rocker arm 74 pivoting back to the horizontal plane, and the printhead cap 68 covered by the cover shell 72. When capping the printhead, the capping assembly 60... Figure 17CThe stop position shown slides toward the printhead 3. The front cam surface 75 of the cam guide 70 engages with the engagement node 77 of the rocker arm 74 so as to pivot the rocker arm upward and allow the cap assembly to slide toward the printhead 3.

[0071] As mentioned above, now refer to Figure 12 and Figure 13 The printhead carrier 30 defines a cavity 34 between its front and rear plates 32. The cavity 34 houses a supply module 80, which includes front and rear PCBs 82 for supplying power and / or data to the printhead 3. A cooling fan 84 is positioned between the PCBs 82 for cooling electronic components using cool air drawn into the cavity 34 from the upper side of the printhead carrier 30. A support 38 defining the top portion of the printhead carrier 30 has an open truss structure that allows cool air to pass through the cavity 34 and circulate between the PCBs 82. The supply module 80 further includes ink connectors 86 for engaging complementary ink ports 88 at opposite ends of the printhead 3. The supply module 80 forms ink and electrical connections with the printhead 3 when the printhead (secured in its printhead insert assembly 100) is mounted onto the printhead carrier 30, as will be explained in more detail below.

[0072] Figure 18 and Figure 19 The printhead insert assembly 100 is shown separately. (See example...) Figure 18 As shown, the insert is in its closed position, wherein the printhead 3 is repositionably secured within the insert 102 and surrounded by the insert from all sides. Figure 19 In this configuration, the insert 102 is in its open position, which allows the printhead 3 to be removed from the insert, provided that the printhead insert assembly 100 is completely detached from the printhead carrier 30. In other words, the printhead 3 must be combined with the insert 102 to form the printhead insert assembly 100, and then the printhead (e.g., a replacement printhead) can be mounted in the inkjet module 1 by fastening the insert 102 to the printhead carrier 30, thereby forming a printing module 81, which includes the printhead carrier 30, the supply module 80, the insert 102, and the printhead 3 fastened to each other.

[0073] The insert 102 is configured for removably fastening to the printhead carrier 30 via a pair of screw-on fasteners 42, which extend vertically through the height of the printhead carrier 30. Each screw-on fastener 42 has a screw lever 43 and a screw-on end, one end of which is accessible to the user from above the printhead carrier 30, and the screw-on end protruding through a recessed opening 41 in the corresponding carrier reference block 40. Figure 14The upper surface of the insert 102 has a pair of reference pins 104 configured to engage complementaryly with recessed openings 41 in the carrier reference block 40. For mounting the printhead insert assembly 100, each screw-on fastener 42 passes through the hollow hole 105 of the corresponding reference pin 104 and is screwed into the threaded nut insert 106 of the insert 102. Thus, the printhead insert assembly 100 can be securely fixed to the printhead carrier 30 through precise reference engagement between the reference pins 104 and the recessed openings 41 in each carrier reference block 40. The insert 102 enables the use of relatively large reference pins 104, separate from the printhead 3, for highly accurate and repeatable reference positioning between the printhead carrier 30 and the printhead insert assembly 100.

[0074] The printhead insert assembly 100 is screwed onto the printhead carrier 30 via the carrier reference block 40, simultaneously forming an ink connection and electrical connection between the printhead 3 and the supply module 80. Ink ports 88 at opposite ends of the printhead 3 are raised to engage with ink connectors 86 of the supply module 80. Similarly, electrical contacts 109 extending along opposite longitudinal sides of the printhead 3 make electrical contact with complementary PCB contacts 89 of corresponding PCBs 82 in the supply module 80. During installation of the printhead insert assembly 100, as the printhead 3 is raised between the PCBs, the spring-biased PCB mounting plate 90 of the supply module 80 allows the PCBs 82 to laterally flex away from each other. The spring bias provides a reliable electrical connection, while the required insertion force (for ink connection and electrical connection) is provided by screw-on fasteners 42, which can be easily operated by the user using a screw-on lever 43. Accordingly, this arrangement eliminates the movable supply components and two-stage ink connections and electrical connections described in US 10,967,638.

[0075] The printhead insert assembly 100 can be positioned at the printhead lowered position ( Figure 10 ) or printhead raised position ( Figure 12 Secured to the printhead carrier 30, depending on which configuration is more accessible in the specific modular setup of the inkjet module 1. For example... Figure 14 As shown, the printhead insert assembly 100 has been removed from the printhead lowered position.

[0076] Now for reference Figure 19 and Figure 22The insert 102 is configurable in an open position for printhead removal and insertion. The insert 102 includes a first longitudinal side rod 110 and a second longitudinal side rod 112 extending parallel to opposite longitudinal sides of the printhead 3, and a pair of shorter transverse end rods 114 that interconnect each end of the longitudinal side rods to define a rectangular insert cavity 115. The first longitudinal side rod 110 and end rods 114 are fixed, while the second longitudinal side rod 112 is movable toward and away from the first longitudinal side rod between an open and a closed position.

[0077] Each end bar 114 has a locating pin 116 that receives a movable second longitudinal side bar 112. The sliding movement of the second longitudinal side bar 112 relative to the fixed locating pin 116 provides relative linear movement of the second longitudinal side bar toward and away from the first longitudinal side bar 110.

[0078] Movement of the second longitudinal side lever 112 is achieved by a locking mechanism that positions the insert 102 in a closed or open position. The locking mechanism includes a pair of insert levers 120, each pivotally attached to a corresponding end lever 114 and having a pivot axis perpendicular to the horizontal plane of the insert (i.e., parallel to the direction of droplet ejection from the printhead 3). Each insert lever 120 defines a cam slot 122 that engages with a corresponding follower pin 124 extending parallel to the pivot axis at opposite ends of the second longitudinal side lever 112. By means of the cam engagement between the cam slot 122 and the follower pin 124, pivotal movement of each insert lever 120 away from its corresponding end lever 114 causes linear movement of the second longitudinal side lever 112 away from the first longitudinal side lever 110 to open the insert 102. Conversely, the pivoting motion of each insert lever 120 toward the corresponding end bar 114 causes the second longitudinal side bar 112 to move linearly toward the first longitudinal side bar 110 in order to lock the insert 102 closed. Each insert lever 120 has a finger grip portion 126 at the end opposite to the pivot axis for the user to actuate the locking mechanism.

[0079] The insert 102, in its closed position, is configured to form an ink mist seal around the printhead 3. The ink mist seal prevents ink mist from entering the supply module 80, thereby protecting the sensitive electronic circuitry on the PCB 82 from any ink mist contamination generated during the printing process. The ink mist seal includes a pair of opposing first and second longitudinal lips 130, which project inwardly toward the printhead from corresponding first and second longitudinal side bars 110 and 112. Each lip 130 engages with a longitudinal edge region 132 of the printhead 3 to form part of the ink mist seal.

[0080] In order to insert the printhead 3 into the insert 102, the insert is first configured to its open position, such as... Figure 22As shown. Then the print head is tilted at an angle ( Figure 21 The printhead is laterally guided toward the first longitudinal side bar 110 into the open insert cavity 115. First, the first longitudinal flange 134 located on one side of the printhead 3 is held at an angle below the longitudinal lip 130 of the first longitudinal side bar 110 to overlap with the lip. Then, the printhead is rotated about its longitudinal axis into a plane parallel to the plane of the insert. Printhead references 136 located at opposite ends of the printhead 3 and complementary insert references 138 (…) Figure 23 The two parts are engaged to ensure that the printhead is accurately and repeatably positioned within the insert.

[0081] When the printhead 3 is correctly positioned within the open insert ( Figure 19 The insert lever 120 pivots inward to close the second longitudinal side bar 112 and lock the insert 102 in its closed position, thereby forming a locked printhead insert assembly 100. Figure 18 The closing of the insert 102 moves the longitudinal lip 130 of the second longitudinal side bar 112 toward the printhead 3 to complete the ink mist seal, wherein each longitudinal flange 134 of the printhead is positioned below and overlaps its respective longitudinal lip.

[0082] The complete printhead insert assembly 100 can then be secured to the printhead carrier 30 using the screw fastener 42 as described above. When removing the printhead, the reverse procedure is followed, thereby removing the printhead insert assembly 100 from the printhead carrier 30, opening the insert using the insert lever 120, and tilting the printhead 3 from the opened insert 102.

[0083] Print head skew adjustment in printing unit 200 In the printing unit 200, the alignment of the upstream and downstream printheads 3 is crucial to ensuring optimal print quality. While the standardized arrangement described above within each inkjet module 1 and between a pair of inkjet modules in the printing unit 200 provides robust positioning of the printheads 3, small misalignments between printheads are somewhat unavoidable in printing systems comprising multiple printheads, especially when the printheads are replaceable. These misalignments can typically be compensated electronically along the printhead's path. x axis, y shaft and z Non-optimal axis alignment (if necessary, use information obtained from test mode during system setup).

[0084] However, misalignment between printheads is more difficult to compensate for electronically; therefore, print quality is usually optimized by mechanically minimizing this misalignment. Figure 5 and Figure 10The nominal coordinate system shown refers to the rotational misalignment of one printhead relative to another about the z-axis. Ideally, the two printheads should be parallel.

[0085] Figure 24 A modified printhead insert assembly 150 is shown, comprising a modified printhead insert 152 and a printhead 3, adapted to correct misalignment between a pair of printheads in a printing unit 200. In the modified printhead insert 152, a cantilever spring 154 is formed at one end of the printhead insert via a micromachined slot 156 defined in a first (fixed) longitudinal side bar 110. A screw adjuster 158, received via a threaded opening in the first longitudinal side bar 110, engages with the cantilever spring 154 to push the cantilever spring toward and away from the printhead 3. Since the printhead 3 is positioned relative to the cantilever spring 154, the screw adjuster 158 is moved along... x When the shaft is turned, the adjustment mechanism can apply a slight rotational movement to one end of the printhead 3 via the movement of the cantilever spring 154. Accordingly, the adjustment mechanism 158 can be used to make fine skew adjustments to the printhead 3 in place.

[0086] Typically, in the printing unit 200, the printhead 3 of one inkjet module is considered a reference printhead, relative to which the skew of the other printhead is adjusted. Therefore, only one printhead insert needs to have a cantilever spring 154 and a rotary adjuster 158, but in practice it is convenient for both printhead inserts to be identical.

[0087] As described above, the adjustment knob 158 is preferably accessible when the printing module 200 is set up for use. Therefore, the rear wall 14 of each module chassis 10 typically has a suitable window when the printing unit 200 is in its clamshell closed position (e.g., Figure 1 As shown), this window allows external access to the rotary adjuster 158 (whether in the printhead raised or printhead lowered position).

[0088] Optimized airflow in the printing area Optimizing airflow through the print zone during high-speed printing is known to improve print quality, particularly for high PPS printing, i.e., printhead-to-paper pitch (PPS) greater than about 1 mm (e.g., 1 mm to 10 mm or 1 mm to 5 mm). For example, US 6,997,538 (granted to Hewlett-Packard Development Company, LP) describes an inkjet printer having means for generating airflow through the print zone in the direction of media travel. The airflow is generated using an upstream blower, a downstream suction unit, or a combination thereof. Subsequent research by the applicant has confirmed the importance of controlling airflow through the print zone as a means of optimizing print quality. A uniform airflow creates a pressure gradient over the print zone, which tends to stabilize the vortices associated with the jetting ink droplet flow. These vortices are generated by the interaction between the ink droplet flow and the couette flow caused by the moving print media. Without a forced airflow through the print zone to create a pressure gradient, the vortices tend to drift, producing a distinctive print artifact known as a “tiger stripe” or “wood grain” effect.

[0089] refer to Figures 25 to 27 This shows a modified printing system 300, which is similar to the one described above. Figures 1 to 6 The described printing system 200, however, has a gap strip 302 located in the space between the corresponding upstream printhead 3A and downstream printhead 3B of the upstream inkjet module 1A and the downstream inkjet module 1B. In relevant cases, the same reference numerals are used to indicate the same features in printing system 200 and the modified printing system 300.

[0090] The gap strip 302 extends between opposing side bars 205 of the unit chassis 204, i.e., parallel to the end bar 207 and the longitudinal axes of the upstream printhead 3A and the downstream printhead 3B. The gap strip 302 includes a polymer plate 304 connected to the underside of a metal support rod 306, defining a flat lower surface positioned relative to the printing medium 301 at substantially the same height as the lower surfaces of the printheads 3A and 3B. In some embodiments, the height of the gap strip 302 and / or the polymer plate 304 is adjustable to match the relative height of the polymer plate and the printheads 3A and 3B.

[0091] The polymer plate 304 has a width dimension that extends substantially completely across the space between the upstream printhead 3A and the downstream printhead 3B (e.g., across at least 70%, at least 80%, or at least 90% of the inter-printhead space) and a length dimension that is at least as long as the printheads. By filling the inter-printhead space in this way, a relatively uniform airflow is provided from the upstream printing area 305, through the downstream printing area 307, and toward the suction nozzle 222 of the aerosol extractor 212. Figure 27 This optimized airflow advantageously stabilizes the eddies associated with the ink droplet streams ejected from printheads 3A and 3B, thereby minimizing stray satellite droplet misalignment and optimizing print quality. Without the gap strip 302, the airflow is less uniform, and the suction nozzle 222 has minimal impact on the upstream printing area 305, instead drawing air primarily from the inter-printhead space and surrounding area.

[0092] Additionally, the polymer plate 304 advantageously minimizes ink mist condensation on the gap strip 302. For example, condensation on metal surfaces could undesirably drip onto the printing media and contaminate the printed image.

[0093] like Figure 26 As shown, the upper surface of the support rod 306 has a pair of recessed portions 308, which are configured to receive complementary portions of the upstream inkjet module 1A and the downstream inkjet module 1B. Specifically, when the printing unit 300 is in its clamshell closed position, the bracket sidewall 29 of each inkjet module is received in the corresponding recessed portion 308.

[0094] It should be understood that the gap strip 302 can be used to position each inkjet module relative to the unit chassis 204. However, in Figures 25 to 27 In the illustrated embodiment, the reference positioning of each inkjet module 1 is achieved via a corresponding magnetic reference 310, which is secured to each module chassis 10 and engages with a complementary chassis reference block in the form of an electromagnet 312. Thus, reliable reference positioning of each inkjet module 1 relative to the unit chassis 204 is achieved via magnetic adsorption, as described in US 11,376,869, the contents of which are incorporated herein by reference. Release of the inkjet module 1 from the corresponding printing position can be controlled by the electromagnet 312.

[0095] refer to Figures 28 to 30 A variation of the gap strip 302 is shown, in which an elastically deformable polymer membrane 320 is attached to the lower surface of the support rod 306 instead of the polymer plate 304. The membrane 320 has a first wing 322A and a second wing 322B, which extend upstream and downstream, respectively, from the longitudinal edge of the support rod 306 relative to the media feed direction. Figure 28 and Figure 29 As shown, in its non-deformable configuration, the film 320 is generally planar, with its plane extending parallel to the printing medium 301. However, the downward movement of the printing module (with the corresponding insert 102) toward the printing medium 301 causes the upstream wing 322A and downstream wing 322B of the film 320 to bend downward toward the printing medium by means of engagement with the corresponding inserts of the upstream inkjet module 1A and downstream inkjet module 1B. Figure 30Accordingly, each of the upstream wing 322A and the downstream wing 322B acts as a resilient wing that can bend toward the printing medium 301 via engagement with the corresponding insert 102.

[0096] Since the membrane 320 is attached along the longitudinal middle portion of the support rod 306 via the retaining pin 324, the membrane 30 is in Figure 30 The printing position shown employs a concave profile between the upstream printhead 3A and the downstream printhead 3B. The engagement between the insert 102 and the corresponding wings 322A and 332B forms a partial seal between them, sufficient to minimize airflow through the space between the upstream printhead 3A and the downstream printhead 3B. Therefore, with Figures 25 to 27 Compared to the arrangement shown, membrane 320 provides a more effective seal across the space between the upstream printhead 3A and the downstream printhead 3B, because the polymer plate 304 can only extend partially across this space depending on the height of the printhead relative to the printing medium 301. Membrane 320 can accommodate a range of different printhead heights while still maintaining an effective seal and optimizing airflow through the printing area.

[0097] From the foregoing content and Figure 30 The general further understands that the insert 102 corresponding to the downstream printhead 3B is simultaneously connected to the downstream wing 322B and the tab portion 224 of the aerosol extractor 212 (see...). Figure 7 The dual function of the insert 102 is particularly advantageous for optimizing airflow through the printing zone by controlling the height of the suction nozzle 222 to match the height of the printhead 3B and the configuration of the membrane 320.

[0098] Of course, it should be understood that the invention has been described by way of example only, and modifications to the details are possible within the scope of the invention as defined in the appended claims.

Claims

1. A printing unit, comprising: Unit chassis; A pair of opposing inkjet modules are mounted on the unit chassis, and each inkjet module includes a corresponding printhead. The pair of opposing inkjet modules are each pivotally mounted on the unit chassis to allow them to pivotally move towards and away from each other between a clamshell-closed configuration and a clamshell-open configuration. In the clamshell-closed configuration, the front faces of the pair of opposing inkjet modules are parallel to each other; in the clamshell-open configuration, the front faces of the pair of opposing inkjet modules are not parallel to each other. The characteristic feature is that: The printing unit is configured to print only in the clamshell-like closed configuration; and The printhead of each inkjet module is replaceable only in the clamshell-style open configuration.

2. The printing unit as claimed in claim 1, wherein, When the pair of opposing inkjet modules are in the printing position, they are positioned with reference to the opposite sides of the common chassis reference block of the unit chassis.

3. The printing unit as claimed in claim 1, wherein, Each inkjet module can pivot independently relative to the unit chassis.

4. The printing unit as claimed in claim 1, wherein, The first inkjet module of the pair of opposing inkjet modules is mounted in a forward orientation, while the second inkjet module of the pair of opposing inkjet modules is mounted in a reverse orientation.

5. The printing unit as claimed in claim 4, wherein, Each inkjet module includes a module chassis that supports its respective printhead, and each module chassis includes a base plate, wherein a rear wall and an end wall extend upward from the base plate.

6. The printing unit as claimed in claim 5, wherein, Each substrate is C-shaped in plan view and has a pair of lateral arms that extend parallel to the media feed direction from opposite ends of a longitudinal base member that extends perpendicular to the media feed direction. Each substrate defines an open longitudinal slot for receiving a corresponding printhead.

7. The printing unit as claimed in claim 6, wherein, The pair of opposing inkjet modules in the forward and reverse orientations have opposing C-shaped substrates, such that the pair of open longitudinal slots are positioned close to each other relative to the pair of longitudinal base members.

8. The printing unit as claimed in claim 7, wherein, Each inkjet module includes a cap, and a pair of said caps are positioned remotely relative to a pair of said printheads.

9. The printing unit as claimed in claim 5, wherein, The unit chassis includes a rectangular frame having a pair of chassis side rods extending parallel to the medium feeding direction, and a chassis front rod and a chassis rear rod that interconnect the chassis side rods.

10. The printing unit as claimed in claim 9, wherein, The module chassis is pivotally mounted on the side rod of the chassis about a pivot axis perpendicular to the medium feeding direction.

11. The printing unit as claimed in claim 10, wherein, Each chassis side bar has a chassis reference block positioned between the pair of opposing inkjet modules, such that, in a clamshell closed configuration, the respective substrates in the pair of opposing inkjet modules are positioned with reference to opposite sides of each chassis reference block.

Images