Patent Application
20250042154
Industrial inkjet printers are used to apply materials to large substrates to form devices of all kinds. The substrates can be rigid or flexible, thick or thin, and can be made of an array of materials. The most common types of substrates used in this way are substrates made of various types of glass, which are processed to make electronic displays such as televisions and displays for smart phones.
An inkjet printer uses a printhead with nozzles that dispense a print material for deposition onto a substrate. Today's industrial inkjet printers deposit very small droplets of print material with extremely high accuracy to form very small, or very thin, precisely located structures on the substrate. To increase production speed, multiple printheads are commonly used to perform a single print job. Due to the extreme precision of modern inkjet printing, precision alignment of the printheads is helpful to make sure printed droplets land in desired locations. As the size of printed droplets declines toward 10 μm, the need for printhead alignment increases.
Sometimes, a printhead of an industrial scale inkjet printer needs to be swapped. Today's printheads commonly come in multiples, with several printheads to a cartridge, and an assembly of printheads used for a particular printer might need multiple cartridges of printheads. To minimize printer downtime while printheads and cartridges are swapped, quick removal and insertion of printhead cartridges is useful while making secure connections with ink supply and electrical components. It is also helpful if the cartridges can all be aligned with each other.
Finally, operation of an inkjet printer typically results in printer components changing temperature. For printheads and cartridges, the temperature changes can change alignments and positions of nozzles. Such changes often require recalibration of the printer based on the new positions of the nozzles, since the nozzles can change position by several microns depending on the operating temperature ranges. For example, a printhead can be installed and aligned within one print cartridge, and several cartridges put together to form a printhead assembly, all at room temperature. When the printhead assembly rises in temperature during production, the alignment of all the printheads and nozzles can change. Time-consuming calibration operations are needed to detect and react to these changes, slowing down production. To the extent these changes can be managed and minimized, production speed can be increased.
There is an ongoing need for methods and apparatus for achieving, maintaining, and managing extremely precise alignment of printheads for industrial scale inkjet printers.
Embodiments described herein provide a printhead assembly for an inkjet printer, the printhead assembly comprising a printhead having a plurality of nozzles; a nozzle plate attached to the printhead; and a base plate attached to the nozzle plate by at least three fasteners that provide independent positioning of the nozzle plate with respect to the base plate in three independent dimensions.
Other embodiments described herein provide a printhead assembly for an inkjet printer, the printhead assembly comprising a support plate; a supply plate comprising a plurality of alignment features; a plurality of print tiles disposed between the support plate and the supply plate, each print tile comprising a plurality of printheads, each printhead comprising a plurality of nozzles; a nozzle plate attached to each printhead; a base plate attached to the nozzle plate by at least three fasteners that provide independent positioning of the nozzle plate with respect to the base plate in three independent dimensions; and a fluid manifold comprising at least one alignment feature that matches one of the alignment features of the supply plate.
Each nozzle plate 104 is attached to the base plate by three fasteners that provide independent positioning of the nozzle plate with respect to the base plate in three independent dimensions. Each nozzle plate 104 has a long dimension 110, a short dimension 112, a first end 114, and a second end 116 located opposite from the first end 114 along the long dimension 110. A first fastener 118 is located at the first end 114, on a central axis of the nozzle plate in the direction of the long dimension 110, and is operable to position the nozzle plate 104 along the long dimension 110 thereof. The first end 114 has a notch 120 formed therein that is symmetrical with respect to the long dimension 110. In this case, the notch 120 has two straight sides that merge to a point located on the central axis of the nozzle plate 104 that extends along the long dimension 110. The first fastener 118 provides a positioning force at the first end 114 by providing equal forces on the two sides of the notch 120. The forces cancel in the direction of the short dimension and add in the direction of the long dimension to provide the capability to position the nozzle plate 104 in the direction of the long dimension 110 by operating the first fastener 118. The base plate has a low thermal expansion coefficient to provide dimensional stability for maintaining positional relationship of the printheads and other components of the printhead cluster 100. In one example, the base plate has a thermal expansion coefficient that is less than about 20×10−6/K.
Referring again to
A second fastener 122 is located at the second end 116 and is operable to position the nozzle plate 104 in the direction of the short dimension 112 thereof. The second fastener 122 is located along a side 124 of the nozzle plate 104 near the second end 116. In this case, because the second fastener 122 is located along the side 124 of the nozzle plate 104 near the second end 116, the second fastener 122 is operable to rotate the nozzle plate 104 about an axis perpendicular to the nozzle plate 104. That is to say, operating the second fastener 122 can rotate the nozzle plate 104 about an axis perpendicular to a plane defined by the long dimension 110 and the short dimension 112, which is a plane substantially parallel to the base plate 106, of the nozzle plate 104.
As the second fastener 122 is operated, the second end 116 is moved in the direction of the short dimension 112 while the first end 114 rotates about the first fastener 118. If the first fastener 118 is not operated simultaneously, the first fastener 118 maintains the position of the nozzle plate 104 with respect to the long dimension 110, and maintains the location of the first end 114, while the second fastener 122 changes the location of the second end 116, resulting in rotation of the nozzle plate 104 about the fixed location of the first fastener 118. The distance the second fastener 122 moves the nozzle plate 104 is short, so the second fastener 122 effectively moves the nozzle plate 104 in a quasi-linear fashion substantially parallel (i.e. differentially non-parallel) to the short dimension 112. The second fastener 122 is also operable to align the nozzle plate 104 with any desired feature or direction, but most notably the second fastener 122 of each nozzle plate 104 can be operated to align the nozzle plates 104, one to another, so that all the nozzle plates 104 of the printhead cluster 100 can be aligned. By operating the first fasteners 118 of each nozzle plate 104, all the nozzle plates 104 of the printhead cluster 100 can be aligned in two independent dimensions defining a plane substantially parallel to the plane of the base plate 106.
An opposing member 130 can be provided to provide restorative force in the direction of the long dimension 110. The opposing member 130 is located at the second end 116 of the nozzle plate 104, impinging on the second end 116. The opposing member 130 is a resilient member configured to apply force to the nozzle plate in a direction substantially opposite to the direction of the force applied by the first fastener 118. As the first fastener 118 is operated to force the nozzle plate 104 toward the opposing member 130, away from the first fastener 118, the opposing member 130 yields to allow the nozzle plate t102 to move away from the first fastener 118. The opposing member 130 stores restorative potential energy as the nozzle plate 104 moves away from the first fastener 118. As the first fastener 118 is operated to move the nozzle plate 104 toward the first fastener 118, the restorative potential energy stored in the opposing member 130 is released to move the nozzle plate 104 toward the first fastener 118.
In some cases, the opposing member 130 can be a first opposing member, and the printhead cluster 100 can have a second opposing member 132 located opposite from the second fastener 120 to provide a similar restorative force that moves the nozzle plate 104 toward the second fastener 120 when the second fastener 120 is operated to allow the nozzle plate 104 to rotate toward the second fastener 120. The first and second opposing members 130 and 132 can be spring members such as leaf springs or coil springs, or other resilient members such as homogeneous compressible members, for example, rubber stops.
It should be noted that the opposing members 130 and 132 are useful in managing the effects of thermal expansion during temperature cycles. As the printhead cluster 100 changes temperature, thermal expansion of the components of the printhead cluster 100 causes a change in dimensions and relative positions of the components. Because the components are nearly identical in composition and close in relative location, like components (for example all the nozzle plates 104) will have almost identical thermal response. The nozzle plates 104, for example, will grow in dimension as temperature rises. The various fasteners impinging the nozzle plates 104 will remain in place, so the thermal expansion will increase force on the opposing members 130 and 132, which will yield. As temperature then falls in a cycle, the opposing members 130 and 132 will relax with the shrinking dimension of the nozzle plates 104, effectively maintaining all the nozzle plates 104 in alignment through the temperature cycle.
A third fastener 140 can be provided to provide adjustment of the nozzle plate 104 in a third direction independent from the direction of the long dimension 110 and the short dimension 112. In this case, one or more spacers 142 is used with the third fastener 140 of each nozzle plate 104 to adjust the position of the nozzle plate 104 in the third direction. In this case, two fasteners 140 are used to position the nozzle plate 104 in the third direction, one located the first end 110 and another located at the second end 112. The two fasteners 140 can be operated independently, using respective spacers 142, to additionally allow leveling of the nozzle plate 104, and the printhead 102 attached thereto. The spacers 142 are disposed between the nozzle plate 104 and the base plate 106, and generally under the force area of the third fastener 140, to position the nozzle plate 104, in the vicinity of the third fastener 140, at a desired location along the third direction. The spacers 142 can have any desired thickness to allow for parametric positioning of the nozzle plate 104 along the third direction. In one example, each spacer 142 has a thickness of 25 μm, but other different thicknesses can be used. The spacers 142 generally protrude outward between the nozzle plate 104 and the base plate 106 to facilitate manipulation of the spacers 142. It should be noted that more than one spacer 142 can be used at a single location, and no spacers 142 can be used at some locations, depending on what adjustment is needed to the nozzle plate 104 position and angle with respect to the third direction.
The nozzle plates 104, with printheads 102 attached, can be aligned according to the three directions in any order. In one process, the nozzle plate 104 is loosely attached to the base plate 106. A first nozzle plate 104 of the printhead cluster 100 is set at a fixed position with respect to the long dimension 110 using a fixed-position fastener 144 at the notch 120. The other nozzle plates 104, with printheads 102 attached, are aligned with the first nozzle plate 104, at the respective first ends 114 thereof using the first fasteners 118. The second fasteners 122 of all the nozzle plates 104 are operated to align all the nozzle plates 104, and may be used to align all the nozzle plates 104 with a standard alignment, such as an edge of the base plate 106. The third fasteners 140 are then operated, with spacers 142, to align and level the nozzle plates 104 with respect to the third direction. The base plate 106 has four recesses 146 for receiving posts of a tile structure to be described below. The recesses 146 allow the printhead cluster 100 to be integrated into a print tile that supplies print fluid to the printhead cluster 100 and controls operation of the printhead cluster 100.
Print fluid conduits are attached to the printhead cluster 100 to supply print fluid to the printheads 102.
The supply conduit 202 and the return conduit 206 are also attached to a fluid manifold 210, which is used to fluidly connect the tile component 200 with a print supply system (not shown).
The fluid manifold 210 has two alignment features 216 that aid installation of a print tile that has the tile component 200 as a member. The print tile is described further below. The alignment features 216 are located between the fluid supply port 212 and the fluid return port 214, and in this case are positioned slightly displaced from a line connecting the centers of the fluid supply port 212 and the fluid return port 214. The alignment features 216 can be at any convenient location of the fluid manifold 210. The alignment features 216 can be protrusions or recesses. In this case, the alignment features 216 are recesses for receiving alignment protrusions to align the fluid manifold 210 with fluid supply components of the print supply system (not shown in
The fluid manifold 210 has an engagement feature 218 for securing a print tile having the tile component 200 to the print supply system. In this case, the engagement feature 218 is a threaded recess for receiving a screw that can be operated to secure the engagement of the print tile with the print supply system. The fluid manifold 210 has an outer wall 220 that defines an interior surface 222 of the fluid manifold 210. The outer wall 220 is raised above the interior surface 222 to provide fluid containment when the tile component 200 is disengaged from the print supply system, in the event some fluid escapes containment with in the print supply system or the supply and return conduits 202 and 206 during removal of the print tile. The engagement feature 218 is provided in a platform 224 that has an elevation substantially equal to the elevation of the outer wall 220 to prevent fluid intrusion into the engagement feature 218. Fluid intrusion into the engagement feature 218 is undesirable in this case because the fluid manifold 210 uses a sensor to detect engagement of the screw with the engagement feature 218 for secure installation of the print tile. The platform 224 could have an elevation higher than the elevation of the outer wall 220, and in some cases could have an elevation slightly lower than the elevation of the outer wall 220. If the elevation of the platform 224 is too low, there is a risk of print fluid intruding into the engagement feature 218 when the print tile is disengaged from the print supply system.
Referring again to
Other types of sensors can be used to detect engagement. For example, an optical sensor can be located within the fluid manifold 210, rather than attached to the underside 228. Also, an electrical conductivity sensor can be used to detect contact between the screw and the engagement feature, so long as both have electrically conductive elements.
The tile component 200 is mated with an electrical component to form a print tile.
An electrical component 302, shown on the left, is mated with the tile component 200 to form the print tile 300. The electrical component 302 comprises a tile structure 304 that supports a control box 306 and an interface circuit 308. The interface circuit 308 is implemented, in this case, as a circuit board. A wiring electrically connects the interface circuit 308 to the control box 306. The control box 306 contains circuitry to control operation of the printheads 102. When the electrical component 302 is mated with the tile component 200, a wiring is used to connect the control box 306 to the printheads 102.
The tile structure 304 has a first section 310 that supports the interface circuit 308 and provides alignment support to the interface circuit 308 and fluid manifold 210 to facilitate quick and easy connection of the print tile 300 with the print supply system, as illustrated further below. The first section 310 has a first plate 312 and a second plate 314 connected by four upper posts 316 (two are visible in
The second plate 314 of the first section 310 is attached to a second section 322 of the tile structure 304, which has a mounting plate 324 for attachment to the second plate 314. The second plate 314 and the mounting plate 324 are fastened together using flexible fasteners 326 that have flexibility to allow the first section 310 to shift with respect to the second section 322. The flexible fasteners 326 are resilient such that the first section 310 and second section 322 can shift slightly to facilitate easy connection with the print supply system, but the first section 310 and second section 322 remain securely fastened together. In one embodiment, the flexible fasteners 326 are spring shoulder screws, but any flexible fastener can be used.
Referring again to
The second section 322 also has a control box support plate 312 that attaches to the four lower posts 324. The control box support plate 312 supports the control box 306 and provides rigidity to the second section 322, and to the print tile 300 when the electrical component 302 is mated with the tile component 200.
The first plate 312 has an orientation feature 336 to ensure installation of the print tile 300 in the proper orientation. The print tile 300 is installed in a printhead assembly (not shown here) that supports the print tile 300, positions the print tile 300 for printing during operation, and includes the print supply system with which the print tile 300 engages. The printhead assembly has a matching orientation feature that ensures the print tile 300 is installed properly. Here, the orientation feature 336 is a lateral protrusion from an edge of the first plate 312. In this case, the orientation feature 336 protrudes from a long edge of the first plate 312, which is generally rectangular. It should be noted that the first plate 312 can have any convenient shape, and the orientation feature 336 can be located at any convenient location on the first plate 312. Here, the orientation feature 336 has a semi-circular shape, but the orientation feature 336 could have any convenient shape, and instead of a protrusion a recess can be used as an orientation feature. Additionally, any number of orientation features can be used. Here, one orientation feature 336 is shown.
The print tile 300 is inserted through the support plate 402 and is advanced toward the supply plate 404 until connection is made with the print supply system 406. Guides are used to guide insertion of the print tile 300 through the support plate 402 to the supply plate 404. A first guide 408 is attached to the support plate 402, at a side of the support plate 402 facing the supply plate 404 and extending toward the supply plate 404. Here the first guide 408 is a plate-like structure, but in other cases the first guide 408 could be a pair of rails, one rail to guide each side of the print tile 300. Typically, at least two first guides 408 are used, on opposite sides of the print tile 300 (in this view, only one first guide 408 is visible), and in some cases four first guides 408 can be used, one for each side of the rectangular print tile 300. In general, the first guide 408 is shaped to match the shape of the print tile 300. Here, the print tile 300 is rectangular so the first guide 408 is shaped like a plate to conform to a side of the rectangular print tile 300. In other cases, the print tile 300 could have a different shape. Where the print tile 300 has a generally polyhedral shape, the first guide 408 can have a plate shape to guide along a side of the print tile 300, or the first guide 408 can be rail-like to guide along edges of the print tile 300. Where the print tile 300 has a curved side, the first guide 408 can be curved to match. It should be noted that the first guide 408 can be a plurality of individual plates or a single box-like structure that surrounds the insertion path of the print tile 300. The first guide 408 can also be a partially discontinuous plate-like structure, for example two guide rails connected by one or more bars or rods. The first guide 408 could also be a partially discontinuous box-like structure, for example four guide rails extending from the support plate 402 toward the supply plate 404, with the guide rails connected in a rectangular shape by bars or rods. The first guide 408 generally maintains a straight orientation of the print tile 300 as the print tile 300 is inserted through the support plate 402 toward the supply plate 404.
A second guide 410 is attached to the supply plate 404, at a side of the supply plate 404 facing the support plate 402 and extending toward the support plate 402. The second guide 410 has a plurality of plate-like structures 411, each with a sloped profile, to guide the print tile 300 into registration with the various connection features of the supply plate 404 and the print supply system 406. The second guide 410, in this case, is a single member that attaches to the side of the supply plate 404 facing the support plate 402, with the plate-like structures 411 extending toward the support plate 402. Three of the plate-like structures 411 of the second guide 410 are visible in
Each of the plate-like structures 411 has an inner surface 412 that faces inward toward the print tile 300. For each plate-like structure 411, the inner surface 412 slopes away from the print tile 300 as the inner surface 412 extends away from the supply plate 404. In other words, each plate-like structure 411 has a wide end 413 and a narrow end 415, the wide end 413 adjacent to the supply plate 404 and the narrow end 415 opposite from the wide end 413. As the print tile 300 is advanced toward the supply plate 404, the sloped inner surfaces 412 of the plate-like structures 411 narrow the positional freedom of the print tile 300 toward the wide ends 413 of the plate-like structures 411 to guide the print tile 300 into position where the fluid manifold 210 and the connection edge 328 (
The supply plate 404 has two alignment features 414 that engage with the alignment features 216 (
When connection with the print supply system 406 is made, fluid nozzles (not shown) of the print supply system 406 fluidly connect and seal with the fluid ports 212 and 214 of the fluid manifold 210, providing fluid connection with fluid supply and return conduits 420 of the print supply system 406 that are located opposite the supply plate 404 from the fluid manifold 210. Fluid valves 422 control fluid flow from the print supply system 406 into the fluid manifold 210 and the print tile 300, and vice versa. As noted above, the printhead assembly 400 comprises a plurality of the print tiles 300, each connected to the print supply system 406 in the same way. The fluid valves 422, a pair for each print tile 300, are operated by a control system to control fluid flow between each print tile 300 a fluid reservoir for the printhead assembly 400. More than one type of print fluid can be used with such a printhead assembly, where each fluid type is delivered to a distinct subset of the print tiles 300 using dedicated fluid supply and return conduits.
While the foregoing is directed to embodiments of one or more inventions, other embodiments of such inventions not specifically described in the present disclosure may be devised without departing from the basic scope thereof, which is determined by the claims that follow.
This application claims benefit of U.S. Provisional Patent Application No. 63/265,807, filed on Dec. 21, 2021, which is entirely incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2022/081647 | 12/15/2022 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 63265807 | Dec 2021 | US |
