This invention relates to an inkjet printhead. It has been developed primarily to enable monochrome high-speed printing with management of high ink flow rates, hydrostatic pressure surges and bubble venting.
The Applicant has developed a range of Memjet® inkjet printers as described in, for example, WO2011/143700, WO2011/143699 and WO2009/089567, the contents of which are herein incorporated by reference. Memjet® printers employ a stationary printhead in combination with a feed mechanism which feeds print media past the printhead in a single pass. Memjet® printers therefore provide much higher printing speeds than conventional scanning inkjet printers.
Multi-color Memjet® printhead cartridges are generally based on the liquid crystal polymer (LCP) manifold described in U.S. Pat. No. 7,347,534, the contents of which are incorporated herein by reference. A plurality of butted Memjet chips are bonded to a surface of the LCP manifold via an apertured die-attach film. The LCP manifold cooperates with the die-attach film to direct ink from each of five main ink channels to respective color planes of each Memjet® chip via a series of tortuous ink paths.
As described in U.S. Pat. No. 8,025,383, the contents of which are incorporated herein by reference, the LCP manifold additionally incorporates a series of air boxes positioned above the five main ink channels for dampening hydrostatic pressure fluctuations.
Memjet® printhead cartridges, comprising the LCP manifold described above, provide a versatile platform for the construction of a wide range of single-pass inkjet printers, including office, label, wideformat and industrial printers. Industrial printers typically have a plurality of printheads aligned in a media feed direction, as described in U.S. Pat. No. 8,845,080, the contents of which are incorporated herein by reference.
Although the Memjet® printhead cartridge is designed for multi-color printing, some types of printer require monochrome printing only. For example, the industrial printers described in U.S. Pat. No. 8,845,080 employ five monochrome printhead cartridges in order to maximize print speeds. Trivially, the LCP manifold can be plumbed with one color of ink to provide monochrome printing from the nominally five-color Memjet® printhead chips. However, at very high print speeds, the LCP manifold has some practical limitations. The multiple labyrinthine ink pathways from the LCP manifold to the printhead chips may be responsible for unexpected de-priming when the printhead is running at high speeds. Without a sufficient body of ink close to the printhead chips, the chips may become starved of ink under periods of high ink demand and lead to chip de-priming. Secondly, the labyrinthine ink pathways are susceptible to trapping air bubbles; if an air bubble become trapped in the system, the printhead chips will become starved of ink and de-prime. Thirdly, the air boxes provide a relatively stiff compliance in the hydrostatic system; if a particular group of nozzles demands higher ink flow, then the resistance of the air boxes may be too great to allow the hydrostatic system to respond dynamically to the increased demand.
It would therefore be desirable to provide a printhead assembly configured for high-speed monochrome printing, which addresses at least some of the shortcomings of the LCP manifold described above.
In a first aspect, there is provided an inkjet printhead comprising:
The inkjet printhead according to the sixth aspect provides a highly stable structure for printhead chip attachment whilst still providing an open fluidic architecture allowing high ink flow rates and bubble venting pathways.
Preferably, a plurality of the webs are contiguously defined by a wavelike structure extending along a gap defined between the chords.
Preferably, the fluid outlet are generally triangular or bell-shaped.
Preferably, a plurality of butting printhead chips are arranged in a row along the truss structure.
Preferably, the truss structure includes a joint web at chip join regions, wherein each butting pair of printhead chips have respective butting end portions commonly supported by one of the joint webs.
Preferably, the printhead chips are attached to the base via an adhesive film.
Preferably, the printhead chips have a width of less than the distance between the opposite chords, and wherein the adhesive film seals a gap between the edges printhead chips and the chords.
Preferably, the fluid manifold is comprised of a molded polymer material.
Preferably, each fluid outlet is laterally flared from one side of a respective printhead chip towards an opposite side of the printhead chip.
Preferably, a wider end of each fluid outlet extends beyond a longitudinal edge of a respective printhead chip.
Preferably, each fluid outlet is flared towards a respective bubble-venting cavity.
Preferably, each bubble-venting cavity is positioned beyond a longitudinal edge of a respective printhead chip.
Preferably, each bubble-venting cavity has a floor defined by a shelf stepped from a respective fluid outlet.
Preferably, the floor is curved downwards towards the respective fluid outlet.
In a second aspect, there is provided an inkjet printhead comprising:
The printhead according to the second aspect advantageously dampens hydrostatic pressure spikes in the ink whilst maximizing ink flow rates to the printhead chips.
Preferably, the ink manifold comprises an upper part and a lower part, the upper and lower parts cooperating to define the channel.
Preferably, the upper part comprises the flexible film.
Preferably, the lower part comprises the plurality of ink supply outlets.
Preferably, the roof of the ink manifold defines an elongate opening, the flexible film sealing the elongate opening.
In a third aspect, there is provided an inkjet printhead comprising:
The printhead according to the third aspect advantageously provides a mounting arrangement for butting printhead chips, which minimizes occlusion of ink supply channels defined in the backsides of the printhead chips.
Preferably, each ink supply slot is relatively longer than each support web along a longitudinal axis of the ink manifold.
Preferably, each support web occludes less than 10%, less than 8%, or less than 5% of an area of ink supply channels defined in a backside of each printhead chip.
Preferably, each of the support webs supporting the butting end portions has a profile corresponding to the ends of the printhead chips.
Preferably, each of the support webs supporting the butting end portions extends diagonally between fluid outlets at either side thereof.
Preferably, each printhead chip has a mid-portion between opposite end portions, the mid-portion being supported by one or more of the support webs.
Preferably, a number of support webs supporting the mid-portion of each printhead chip is five or less.
Preferably, each fluid outlet has a width of at least half a width of each printhead chip.
Preferably, a combined area of fluid outlets supplying printing fluid to one printhead chip is at least half a total area of the printhead chip.
Preferably, the printhead chips are attached to the base of the ink manifold via an adhesive film, the adhesive film having openings aligned with the fluid outlets.
In a fourth aspect, there is provided an inkjet printhead comprising:
an elongate fluid manifold having a base defining a plurality of fluid outlets; and
a plurality of printhead chips attached to the base of the fluid manifold, each printhead chip receiving ink from one or more fluid outlets,
wherein each fluid outlet extends transversely across the ink manfold and extends at least half a width of each printhead chip.
Preferably, a combined area of fluid outlets supplying ink to one printhead chip is at least half a total area of the printhead chip.
The printhead according to the fourth aspect advantageously maximizes a volume of ink available to each printhead chip, providing high diffusion rates and reducing the propensity for inkjet nozzles to become clogged with ink.
In a fifth aspect, there is provided an inkjet printhead comprising:
an elongate fluid manifold comprising at least one longitudinally extending channel, the fluid manifold having a base defining a plurality of ink outlets, the fluid outlets being spaced apart longitudinally along a floor of the channel;
a plurality of printhead chips bonded to the base of the fluid manifold, each printhead chip receiving ink from one or more fluid outlets; and
a plurality of transverse ribs positioned across the channel, each transverse rib extending upwardly from the floor of the channel,
wherein one or more of the transverse ribs has a recess allowing fluid flow along the floor of the channel between the transverse ribs.
The printhead according to the fifth aspect advantageously enables any trapped bubbles to be flushed from the fluid manifold whilst maximizing the structural rigidity of the fluid manifold.
Preferably, the fluid manifold comprises an upper part and a lower part, the upper and lower parts cooperating to define the channel.
Preferably, the lower part comprises the transverse ribs and the plurality of fluid outlets.
Preferably, the upper part comprises further transverse ribs extending across the channel.
In a sixth aspect there is provided an inkjet printhead comprising:
The printhead according to the sixth aspect advantageously facilitates movement of air bubbles laterally away from a footprint of the printhead chips.
Preferably, the fluid outlets are alternately laterally flared towards opposite longitudinal edges of the printhead chips.
Preferably, a plurality of butting printhead chips are arranged in a row along the base of the fluid manifold.
Preferably, each fluid outlet has a generally triangular or bell-shaped opening facing a respective printhead chip.
Preferably, each fluid outlet is laterally flared from one side of a respective printhead chip towards an opposite side of the printhead chip.
Preferably, the printhead chips are attached to the fluid manifold via an adhesive film, the film having openings aligned with the fluid outlets.
Preferably, a wider end of each fluid outlet extends beyond a longitudinal edge of a respective printhead chip.
Preferably, each fluid outlet is flared towards a respective bubble-venting cavity.
Preferably, each bubble-venting cavity is positioned beyond a longitudinal edge of a respective printhead chip.
Preferably, each bubble-venting cavity has a floor defined by a shelf stepped from a respective fluid outlet.
Preferably, the floor is curved downwards towards the respective fluid outlet.
In a seventh aspect there is provided an inkjet printhead comprising:
The inkjet printhead according to the seventh aspect advantageously facilitates bubble venting such that vented bubbles do not stagnate in fluid outlets and block ink flow pathways to printhead chips.
Preferably, each fluid outlet is configured for moving bubbles towards the bubble-venting cavity.
Preferably, each fluid outlet is flared towards the bubble-venting cavity.
Preferably, each fluid delivery compartment comprises a shelf defining a floor for the bubble-venting cavity.
Preferably, the shelf has an edge curved towards the fluid outlet.
Preferably, one or more fluid supply channels of the printhead chip are aligned with each fluid outlet.
Preferably, the fluid outlets are alternately flared towards opposite longitudinal edges of the printhead chips.
In an eighth aspect there is provided an inkjet printhead comprising:
the air cavities are defined by ribs extending from a roof of the fluid manifold towards the longitudinal channel; and
each rib has a lip protruding beyond a lower surface of the inlet and outlet bosses.
The inkjet printhead according to the eighth aspect advantageously provides self-regulating air cavities, whereby ink flow between inlet and outlet bosses of the fluid manifold is used to shear off any air bubbles protruding from the air cavities.
Preferably, the fluid manifold comprises an upper part and a lower part, the upper and lower parts cooperating to define the channel.
Preferably, the upper part comprises the inlet boss, the outlet boss and the air cavities.
Preferably, the lower part comprises the base.
Preferably, the upper and lower parts each have walls cooperating to define sidewalls of the channel.
In a ninth aspect, there is provided an inkjet printhead comprising:
an elongate fluid manifold comprising at least one longitudinally extending channel, the fluid manifold having a base defining a plurality of fluid outlets, the fluid outlets being spaced apart along a floor of the channel;
Preferably, one or more transverse ribs positioned towards longitudinal ends of the channel have a lower height than transverse ribs positioned at a middle portion of the channel.
Preferably, a height of the transverse ribs is tapered towards the longitudinal ends of the channel.
Preferably, one of more of the transverse ribs has an inverted arch profile.
Preferably, the transverse ribs positioned towards the longitudinal ends of the channel have an inverted arch profile.
Preferably, one longitudinal end of the channel is an inlet end and an opposite longitudinal end of the channel is an outlet end.
Preferably, an ink flow direction changes perpendicularly at the inlet and outlet ends.
Preferably, the fluid manifold comprises an upper part and a lower part, the upper and lower parts cooperating to define the channel.
Preferably, the lower part comprises the transverse ribs and the plurality of fluid outlets.
Preferably, the upper part comprises inlet and outlet bosses meeting with respective inlet and outlet ends of the channel.
Preferably, the upper part comprises further transverse ribs extending across a roof of the channel.
Preferably, the transverse ribs of the lower part and the further transverse ribs of the upper part are offset from each other.
As used herein, the term “ink” is taken to mean any printing fluid, which may be printed from an inkjet printhead. The ink may or may not contain a colorant. Accordingly, the term “ink” may include conventional dye-based or pigment based inks, infrared inks, fixatives (e.g. pre-coats and finishers), 3D printing fluids and the like.
As used herein, the term “mounted” includes both direct mounting and indirect mounting via an intervening part.
Embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings, in which:
Referring to
The body 3 provides stiffness and support for an ink manifold assembly 10 attached to the body via a snap-fitting engagement. The ink manifold assembly 10 comprises an upper ink manifold 12 and a lower ink manifold 14, which are in fluid communication with the fluid couplings 7 and 9 of the body 3. The upper and lower ink manifolds 12 and 14 are typically comprised of a rigid, stiff material, such as a liquid crystal polymer (LCP) although other rigid materials (e.g. glass, ceramic etc) are of course within the ambit of the present invention.
Turning to
The upper ink manifold 12 and lower ink manifold 14 are bonded together and cooperate to define a main ink channel 25 extending longitudinally along the ink manifold assembly 10. Ink is received in the main ink channel 25 from the first fluid coupling 7 via an inlet 27 defined at one end of the upper ink manifold 12; and ink exits the second fluid coupling 9 via an outlet 29 defined in the upper ink manifold 12 at an opposite longitudinal end of the main ink channel 25.
As best shown in
Referring to
The flexible film 36 in combination with the air cavities 26 serves to dampen hydrostatic pressure fluctuations in a manner similar to the air boxes described in U.S. Pat. No. 8,025,383, the contents of which are incorporated herein by reference. For example, when printing suddenly ceases, the flexible film 36 is able to absorb a pressure spike in the ink line and minimize any printhead face flooding as a result. However, the flexible film 36 provides a greater degree of compliance than air boxes alone; therefore, the printhead 1 provides highly effective dampening, especially for high-speed printing. Furthermore, the flexible film 36 is suitable for responding rapidly and dynamically to the high flow rate demands of high-speed printing, because the film can simply flex towards the printhead chips 16 when required. Of course, in some embodiments, the film 36 may be absent and the air cavities 26 may dampen pressure fluctuations with a roof structure similar to the arrangement described in U.S. Pat. No. 8,025,383. In other embodiments, the air cavities may be absent and the film 36 is solely responsible for dampening pressure fluctuations in the printhead 1.
As best shown in
The inlet boss 27A, outlet boss 29A and the longitudinal sidewalls 30 of the upper ink manifold have coplanar lower surfaces which define the upper extent of the main ink channel 25 when the air cavities 26 are filled with air. As best shown in
Referring now to
The arrangement of the main ink channel 25 and ink supply slots 44 is designed to maximize a volume of ink available to each printhead chip 16, whilst providing sufficient support for attaching the printhead chips to the base 41. The end portions of each printhead chip 16 are supported by the diagonal joint webs 46 and a minimum number of transverse webs 48 are positioned between the diagonal joint webs for supporting the middle part of each printhead chip. Each butting pair of printhead chips 16 have respective longitudinal end portions supported on a common diagonal joint web 46.
The ink supply slots 44 have a width, which is at least half the width of the printhead chips 16. Further, a combined area of ink supply slots 44 supplying ink to one printhead chip 16 is at least half a total area of the printhead chip. This arrangement maximizes ink flow to the printhead chips 16 as well as providing an open architecture which allows air bubbles to vent from the printhead chips into the ink manifold assembly 10.
Trapped air bubbles are a perennial problem in the design of inkjet printheads.
Referring to
The truss structure 60 provides excellent mechanical support for mounting the printhead chips 16. The truss webs 66 allow printhead chips 16 to be mounted to the base 41 of the lower ink manifold 14 with minimal chip cracking. Furthermore, the laterally flared ink outlets 61 are optimized for bubble venting as well as ink flow into the printhead chips.
As best shown in
Referring now to
As shown in
Referring to
By reducing the heights of the second ribs 40 towards each end of the main ink channel 25, the flow resistance of the ink is reduced as the ink changes direction from the inlet 27 into the main ink channel, and, likewise, as the ink changes direction from the main ink channel into the outlet 29. This assists in maintaining a relatively constant flow resistance across an entire length of the printhead 1 and minimizes any print artefacts that may otherwise result from a relatively increased flow resistance at the end regions where the ink changes direction.
It will, of course, be appreciated that the present invention has been described by way of example only and that modifications of detail may be made within the scope of the invention, which is defined in the accompanying claims.
The present application claims the benefit of priority under 35 U.S.C. §119(e) of U.S. Provisional Application No. 62/330,776, entitled MONOCHROME INKJET PRINTHEAD CONFIGURED FOR HIGH-SPEED PRINTING, filed May 2, 2016 and of U.S. Provisional Application No. 62/377,467, entitled MONOCHROME INKJET PRINTHEAD CONFIGURED FOR HIGH-SPEED PRINTING, filed Aug. 19, 2016, the contents of each of which are hereby incorporated by reference in their entirety for all purposes. The present application is related to U.S. application Ser. No. ______ (Attorney Docket No. NXM010US), entitled PRINTER HAVING PRINTHEAD EXTENDING AND RETRACTING THROUGH MAINTENANCE MODULE, filed on even date herewith, to U.S. application Ser. No. ______ (Attorney Docket No. NXM001US), entitled INK DELIVERY SYSTEM FOR SUPPLYING INK TO MULTIPLE PRINTHEADS AT CONSTANT PRESSURE, filed on even date herewith, and to U.S. application Ser. No. ______ (Attorney Docket No. NXM002US), entitled INK DELIVERY SYSTEM WITH ROBUST COMPLIANCE, filed on even date herewith, the contents of each of which are hereby incorporated by reference in their entirety for all purposes. These related applications have been identified by Attorney Docket Nos., which will be substituted with corresponding US Application Nos., once allotted.
Number | Date | Country | |
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62330776 | May 2016 | US | |
62377467 | Aug 2016 | US |