Patent Grant
7380911
This application is related to an application entitled STITCHED PRINTING SYSTEM, filed May 10, 2004 under Ser. No. 10/842,196 (U.S. Patent Application Publication No. 2005/248631), which is herein incorporated by reference.
This invention relates to jet printers with enhanced deflection systems, such as continuous ink-jet printers with enhanced swathing capabilities.
Swathing continuous inkjet printers are well known in the art, and are described, for example, in U.S. Pat. No. 6,511,163, and European Patent Application No. EP1197334, which are both herein incorporated by reference. These types of printers generally employ a pair of deflection electrodes that deflect ink drops fired from a nozzle to produce a divergent set of drop paths called a swath. The width of this swath, measured between the two outermost drop paths, typically needs to be calibrated to maintain a predetermined drop spacing and to ensure that drops deposited in adjacent swaths do not overlap. Swathing printers usually perform this type of calibration with a probe or camera that is located away from the print substrate, and this configuration prevents printing and calibration from taking place at the same time.
In one general aspect, the invention features a jet printer that includes a first deflection element located proximate a first portion of an output trajectory of a nozzle, and positioned to deflect printing fluid drops exiting the nozzle in a first direction. A second deflection element is located proximate a second portion of the output trajectory that is further downstream and positioned to again deflect the printing fluid drops in a second direction. The second direction is different from the first direction, but the first and second directions have at least their primary components in a same plane.
In preferred embodiments, the first deflection element can be one of a first pair of deflection electrodes, with the second deflection element being one of a second pair of deflection electrodes. The printer can further include half-tone imaging logic operative to drive the printer to print half-tone images on the print substrate. The printer can be operative to print on a printing plate. The printer can be a proofer that further includes logic operative to simulate another printing process. The printer can further include swathing logic operative to cause the deflection elements to deposit the printing fluid drops at different positions with respect to the first jet printing nozzle. The swathing logic can specify a jumbled firing order. The second deflection element can be oriented to cause the printing fluid drops in different positions in the swathed pattern to travel in at least generally parallel trajectories. A third deflection element can be located proximate a third portion of the output trajectory of the first jet printing nozzle that is further downstream from the nozzle than the second portion, with the third deflection element being positioned to yet again deflect the printing fluid drops in a third direction different from the second direction. The third deflection element can be positioned to cause the second and third directions have at least their primary components in a same plane. The printer can further include an actuating mechanism operative to provide relative motion between a print substrate and the first jet printing nozzle. The actuating mechanism can include a web, a drum, and/or a platen. The actuating mechanism can include a member that supports the first jet printing nozzle. The actuating mechanism can include an actuator for conveying a substrate that includes a three-dimensional printing surface. The actuating mechanism can be operative to convey a large number of the substrates in a continuous process. The actuating mechanism can be operative to hold a plastic bottle. The bottle can be at least a partially non-cylindrical plastic bottle. The actuating mechanism can be operative to convey a large number of plastic bottles in a continuous process. The actuating mechanism can include an actuator for conveying the nozzle relative to a fixed substrate support surface. The actuating mechanism can include a loading mechanism and a feed mechanism. The printer can further include a second jet printing nozzle, a third deflection element located proximate a first portion of an output trajectory of the second jet printing nozzle and being positioned to deflect printing fluid drops exiting the second jet printing nozzle in a third direction, and a fourth deflection element located proximate a second portion of the output trajectory of the second jet printing nozzle that is further downstream from the second jet printing nozzle than the first portion of the output trajectory of the second jet printing nozzle, with the second deflection element being positioned to again deflect the printing fluid drops exiting the second jet printing nozzle in a fourth direction different from the third direction. The output trajectory of the first nozzle can be at least generally parallel to the output trajectory of the second nozzle. The printer can further include interleaving logic operative to provide different, interleaved subsets of data for a single image to the first and second nozzles. The printer can further include an actuating mechanism operative to actuate a first substrate in proximity to the first jet printing nozzle and a second substrate in proximity to the second jet printing nozzle. The printer can further include a charging tunnel that is positioned upstream from the first portion and operative to charge the drops to different degrees. The printer can be a continuous inkjet printer. The first and second directions can be substantially coplanar.
In another general aspect, the invention features a jet printing method that includes firing printing fluid drops, deflecting the printing fluid drops fired in the step of firing in a first step of deflecting, and deflecting the printing fluid drops in a second step of deflecting after the first step of deflecting and in a direction different from a direction in which they were deflected by the first step of deflecting, with the first and second steps of deflecting having at least their primary deflection components in a same plane.
In preferred embodiments, the first step of deflecting can deflect the printing fluid drops fired in the step of firing in a swathed pattern. The second step of deflecting can deflect at least some of the printing fluid drops onto at least generally parallel trajectories. The parallel trajectories can be at least generally parallel to an undeflected trajectory that the printing fluid drops would follow in the absence of the first and second steps of deflecting.
In a further general aspect, the invention features a jet printing method that includes means for firing printing fluid drops, means for deflecting the printing fluid drops fired by the means for firing printing fluid drops, and means for again deflecting the printing fluid drops in a direction different from a direction in which they were deflected by the means for deflecting printing fluid drops, with the means for deflecting and the means for again deflecting having at least their primary deflection components in a same plane
In another general aspect, the invention features a jet printing method that includes receiving a series of printing fluid drops traveling along an input trajectory, and electrostatically redirecting different ones of the printing fluid drops from the input trajectory onto a plurality of different output trajectories having at least one convergence point outside of the part of the printing fluid drop input trajectory followed by the printing fluid drops before the step of redirecting.
In a further general aspect, the invention features a jet printer that includes a first jet printing nozzle, at least one deflection element located proximate an output trajectory of the first jet printing nozzle and being positioned to deflect printing fluid drops exiting the first jet printing nozzle, and dynamic swath adjustment logic responsive to a dynamic swath adjustment signal and operative to dynamically adjust a signal provided to the deflection element during deposition of ink by the first ink jet printing nozzle.
In preferred embodiments, the dynamic swath adjustment signal can be a swath density adjustment signal, with the dynamic swath adjustment logic being operative to adjust a swath density defined by the deflection element within a swath, based on the swath density signal. The variable swath density logic can be operative to adjust a drop separation increment. The dynamic swath adjustment signal can be derived from a three-dimensional print substrate specification. The dynamic swath adjustment signal can be a target swath-width signal, with the dynamic swath adjustment logic being operative to scale the signal provided to the deflection element during deposition of ink by the first ink jet printing nozzle. The dynamic swath-width adjustment logic can further include offset correction logic operative to introduce an offset in the signal provided to the deflection element during deposition of ink by the first ink jet printing nozzle. The dynamic swath-width adjustment logic can be responsive to a substrate advance signal and to substrate shape information. The printer can further include half-tone imaging logic operative to drive the printer to print half-tone images on the print substrate. The print substrate can be a printing plate. The printer can further include an actuating mechanism that includes an actuator for conveying a substrate that includes a three-dimensional printing surface. The actuating mechanism can be operative to hold a container. The actuating mechanism can be operative to hold a three-dimensional plastic object, which can be a plastic bottle. The actuating mechanism can also be operative to hold at least a partially non-cylindrical plastic bottle. The actuating mechanism can also be operative to hold a three-dimensional metal object, and it can be operative to hold a three-dimensional semi-rigid object.
In another general aspect, the invention features a jet printing method that includes generating a series of jet printing fluid drops destined to be deposited on a three-dimensional substrate, deflecting the drops after they are generated but before they reach the substrate, and dynamically adjusting the step of deflecting as the series of drops are being generated.
In preferred embodiments, the step of dynamically adjusting can be operative to dynamically adjust the density of ink deposition within a swath. The step of dynamically adjusting can be operative to dynamically adjust the swath width. The step of dynamically adjusting can be based on a stored three-dimensional profile.
In a further general aspect, the invention features a jet printer that includes means for generating a series of jet printing fluid drops destined to be deposited on a three-dimensional substrate, means for deflecting the drops after they are generated but before they reach the substrate, and means for dynamically adjusting the means for deflecting as the series of drops are being generated.
In another general aspect, the invention features a jet printer that includes a first jet printing nozzle, at least one deflection element located proximate an output trajectory of the first jet printing nozzle and being positioned to deflect printing fluid drops exiting the first jet printing nozzle, and transit time correction logic responsive to a three-dimensional print substrate specification and operative to adjust a transit time correction value.
In preferred embodiments, the transit time correction logic can include depth-dependent transit time correction logic responsive to a three-dimensional print substrate specification and operative to adjust the transit time correction value depending on a distance between the nozzle and a corresponding deposition position. The transit time correction logic can include intra-swath transit time correction logic responsive to a three-dimensional print substrate specification and operative to adjust the transit time correction value within a swath.
In a further general aspect, the invention features a jet printing method that includes generating a series of jet printing fluid drops destined to be deposited on a three-dimensional substrate, deflecting the drops after they are generated but before they reach the substrate, and dynamically adjusting a transit time correction value for the drops depending on a distance between the nozzle and a corresponding deposition position for the drops. In preferred embodiments, the step of dynamically adjusting can take place within a swath.
In another general aspect, the invention features a jet printing method that includes generating a series of jet printing fluid drops destined to be deposited on a three-dimensional substrate, displacing the substrate in a path of the jet printing fluid drops generated in the step of generating, and dynamically adjusting the drop deposition spacing on the substrate drops as the substrate is displaced.
In preferred embodiments, the step of dynamically adjusting can dynamically adjust a deposition time for the drops generated in the step of generating. The step of dynamically adjusting can dynamically adjust a substrate velocity for the step of displacing. The step of dynamically adjusting a substrate velocity can operate by adjusting signals provided to an actuator used in the step of displacing to displace the substrate. The step of displacing the substrate can include rotating the substrate.
Systems according to some embodiments of the invention are advantageous in that they can be designed to deposit drops through collimated, parallel drop paths. This property allows deposition to take place with less regard to the accuracy of spacing between nozzle and substrate. Systems according to the invention can therefore be used to print on sheets of widely varying thicknesses without recalibrating. They may also be less sensitive to local aberrations, such as can arise when a substrate is not tightly held to its support. And they may even be used to print on three-dimensional objects.
Systems according to the invention may also exhibit reduced sensitivity to errors and drifts. Small positioning errors in the drop generation process, for example, may result in smaller print errors than might occur in a divergent swath, because these errors are not magnified by the angle of divergence. And artifacts caused by drum or lead-screw positional errors or eccentricities that affect the distance between nozzle and sheet may be less visible because these types of errors have less of an impact on the swath width at the paper surface. This reduced impact may result in improved print quality, or in a reduced calibration time requirement and a corresponding increase in printer uptime. It may also allow for the use of less expensive mechanical and/or electrical components to achieve a given print quality level. For example, a printer that can tolerate some looseness of its substrate around a drum may not need to be built with a complex vacuum system.
And systems equipped with dynamic swathing adjustment features can allow for printing on a variety of different three-dimensional substrates. Dynamically varying the separation of drops within a swath can allow a printer to evenly deposit ink on a surface that slopes away from a printing nozzle. Dynamically varying the width of a swath can allow the printer can deposit ink onto surfaces at different distances from the nozzle while maintaining a uniform dot pitch. And dynamically varying drop timing can allow the printer to print despite variations in drop travel distance, even within a swath.
Referring to
A drop deposition control module 30 has control outputs that can provide deflection voltages to the deflection elements 20, 22, data signals to the charging tunnel 18, and control signals to the pump 14 and/or other elements of the drop source 12. Note that while the functions of the drop deposition control module are shown as provided in a single grouping, its functions in this and other embodiments may also be combined or further subdivided. And while electrical control and drop deflection are presently considered to be preferable, control and/or deflection can be provided using other principles, such as mechanical, magnetic, and/or pneumatic principles.
A substrate-nozzle feed control module 32 can interface with the drop deposition control module 30, and can control relative motion between the drop source and a print substrate 26. In the embodiment shown in
In operation, the drop source 12 generates a continuous stream of charged drops that follow a predetermined output trajectory. The first pair of deflection electrodes 20A, 20B exerts a force on the drops passing between them, and this force has a magnitude that depends on the charge on the drops and the voltage applied across the deflection electrodes. Adjusting the charge applied to the drops and/or the voltage applied to the electrodes therefore allows the drops to be deflected into one of a series of divergent swathed paths 24A, 24B, 24D, 24E.
The second pair of deflection electrodes 22A, 22B exerts a second force on the drops passing between them, and this force has a magnitude that depends on the charge on the drops and the voltage applied across the second pair of deflection electrodes. The direction of this force is different from that applied by the first set of electrodes, and can be set up to be just sufficient to cause the drops to move from their divergent paths 24A, 24B, 24D, 24E onto a collimated set of coplanar paths 24A,′ 24B,′ 24D,′ 24E′ that are parallel to each other and to the path 24C of an undeflected drop. Other positional arrangements are also possible, however, such as arrangements that produce parallel, divergent, and/or convergent drop paths, and these arrangements may or may not include drop paths parallel to an undeflected path.
In the embodiment shown in
Minimizing throw length, which is the distance from the nozzle to the print substrate, is an important design consideration. This keeps the drops from losing velocity, and thereby reduces positional errors between drops. These kinds of positional errors can be further reduced by accurately modeling the forces acting on the drops during flight, and applying appropriate timing and deflection corrections to individual drops. Suitable methods for this type of approach are disclosed, for example, in U.S. Pat. No. 6,511,163, which is referenced above.
The system can also take the state of the air through which a drop is traveling into consideration. If no drop has been fired for a long time, for example, the relatively still air in a drop's path will slow it more than if a number of drops had just been fired through a same or proximate path by a same or different nozzle. This effect can be corrected for by introducing, for each drop, a delay having a length that depends on the estimated relative air velocity in the air for that drop at that time. The estimated relative air velocity model used to derive the drop delay should preferably take into account earlier drops from the same nozzle as well as earlier drops from other proximate nozzles.
Where the printing system 10 prints on three-dimensional objects with multiple nozzles, the system may also need to compensate for differences in transit times. This is because delays introduced to match the transit times of nozzles at one distance from the nozzles will not necessarily be correct at another distance. The system can make up for these differences by maintaining a series of depth-dependent delay values and selecting the appropriate delay for the each drop, depending on the depth at which the drop is to be deposited.
Systems according to the invention can also benefit from dynamic swath adjustment. This feature allows a printer to adjust its swathing parameters during printing. This kind of adjustment can permit uniform printing on a variety of three-dimensional surfaces.
Referring to
In this embodiment, the printing system 10 can adjust a separation increment DV such that the density of ink deposited on a substrate 26 is uniform. In the case of the bottle shown in
The printing system 10 begins its operation with the data retrieval module 42 retrieving print data from the image storage unit 40. This retrieval operation can take place in an order that is defined by an interleaving sequence and/or a jumbled firing order, and pixel data therefore may not be retrieved sequentially for adjacent positions. For each retrieved pixel (or drop), the DSP processor 44 adds a separation increment and a base offset that correspond to the position of the pixel to be deposited. These added values are part of a profile that is based on the shape of the substrate, and they can be retrieved from a table, computed from a formula, or otherwise derived on the fly from data that specifies at least some information about the shape of the substrate.
The IIR filter further processes the position data to account for other effects, such as adjacent drop and aerodynamic effects, as described in U.S. Pat. No. 6,511,163 and European Patent Application No. EP197334. The final output of the IIR filter for each drop is converted into a deflection voltage, which causes the drop to follow one of the deposition trajectories within the swath.
Other methods for varying the printing intensity may also be employed. For example, it is possible to pre-emphasize the data set to be printed such that the image intensity values it contains vary in relation to the shape of the object, in one or more dimensions. It may also be possible in some applications to skip some of the data to be printed in areas where a lower ink density is required.
Referring to
In operation, the deposition control module 30 adjusts the swath width dynamically during printing. In the case of a rotating substrate with an uneven cross-section, for example, the deposition control module can dynamically scale a deflection voltage to achieve a uniform pixel spacing on all sides. This can be accomplished by adjusting the swath divergence angle θ as the substrate rotates to achieve a constant swath width at the substrate surface. When the distance d1 between a bulge in the substrate 26 and the nozzle 16 is small, therefore, the swath divergence angle θ1 is made relatively large, and when the distance d2 between a dip in the substrate and the nozzle is larger, the swath divergence angle θ2 is reduced. This technique is particularly well suited to depositing ink on rotating plastic bottles with oval cross-sections.
Referring to
Referring to
Referring to
The invention can be applied to a variety of small-scale and large-scale labeling and decorating applications. For example, referring to
While the illustrative embodiment has focused on continuous ink-jet printing, features of the deflection systems according to the invention are also suitable for use in other types of printing systems. These can include other types of ink-based printing systems, such as drop-on-demand inkjet printers. They can also include other types of printing systems, such as direct-to-plate systems, which can dispense a plate-writing fluid. These fluids can include direct plate-writing fluids, which by themselves change properties of plates to allow them to be used in printing presses, and indirect plate-writing fluids, which require further process steps. The printing can be encoded to produce a half tone print, which the human eye tends to perceive as a continuous tone print.
It is also contemplated that features of the invention could be applied to print proofers, which simulate the output of other printers, as described in application Ser. No. 09/962,808, filed Sep. 24, 2001, entitled INKJET PROOFING WITH MATCHED COLOR AND SCREEN RESOLUTION, published as Application No. 20030058291, and herein incorporated by reference. The present invention may further benefit from combination with the teachings of application Ser. No. 10/842,196, entitled STITCHED PRINTING SYSTEM, filed on the same day as this application and herein incorporated by reference.
The present invention has now been described in connection with a number of specific embodiments thereof. However, numerous modifications which are contemplated as falling within the scope of the present invention should now be apparent to those skilled in the art. It is therefore intended that the scope of the present invention be limited only by the scope of the claims appended hereto. In addition, the order of presentation of the claims should not be construed to limit the scope of any particular term in the claims.
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