Patent Application
20180244070
In a printing apparatus, portions of an image printed onto a print medium may be printed by different printing units in the apparatus such as a printhead or die. Variations in printing may occur between the outputs of a plurality of printing units. For large scale printing, a printing technique called tiling may be used. The technique may involve cutting a print job into smaller stripes which are then printed on the printer and stuck side by side according to a predetermined order of how the print job is cut.
The drawings are provided to illustrate various examples of the subject matter described herein in this disclosure (hereinafter “herein” for short, unless explicitly stated otherwise) related to a printing apparatus and are not intended to limit the scope of the subject matter. The drawings are not necessarily to scale.
The printers designed for large printing service provider (“PSP”), particularly those targeting the sign and display (“S&D”) market may be capable of keeping production of prints with minimal intervention for a long period of time (from days to months). In some instances, this capability may enable applications such as outdoor billboard and building wrapper involving a large amount of printing. Due to the size limitation of the commercially available printers, a printing technique called tiling may be used. In one example, tiling may involve cutting the print job into smaller stripes which are small enough to be handled by the printer, printed by the printer, and stuck side by side according to a predetermined order. One important attribute to achieve a desirable level of quality for tiling is the color consistency along long run of the print job.
In some instances, the solutions to achieve color matching, or color consistency, include to reduce the heat applied onto the printheads by using a print mode with a larger number of passes, involving lowering the printhead firing frequency with the same amount of ink fired onto the print medium; and/or to lower the radiation from the drying lamp(s) to the printheads in the carriage during printing. This solution involves also printing primer plots for a few meters to warm up the system and steadily warm up the printheads before the actual print job commences. These meters of print medium used for primer plots generally become wasted.
In view of the aforementioned challenges related to color consistency, the Inventors have recognized and appreciated the advantages of preconditioning a printing apparatus. Following below are more detailed descriptions of various examples related to a printing apparatus, particularly preconditioning an apparatus to achieve robust color consistency in a long print job. The various examples described herein may be implemented in any of numerous ways.
Provided in one aspect of the examples is a method, comprising: preconditioning a printing apparatus, comprising: increasing a temperature of an inkjet printhead in a print zone in the printing apparatus to a first temperature higher than or equal to about a steady state printhead temperature; and increasing a temperature of the print zone such that a portion of a print medium disposed over a portion of a platen in the print zone is at a second temperature higher than or equal to about a steady state print zone temperature; and disposing, using the printhead, an ink at the steady state printhead temperature onto the portion of the print medium to form an image thereon.
Provided in another aspect of the examples is a non-transitory machine-readable medium stored thereon instructions, which when executed, cause preconditioning, using a processor, a printing apparatus, comprising: increasing a temperature of an inkjet printhead in a print zone in the printing apparatus to a first temperature higher than or equal to about a steady state printhead temperature; and increasing a temperature of the print zone such that a portion of a print medium disposed over a portion of a platen in the print zone is at a second temperature higher than or equal to about a steady state print zone temperature; and disposing, using the printhead, an ink at the steady state printhead temperature onto the portion of the print medium to form an image thereon.
Provided in another aspect of the examples is a printing apparatus, comprising: a print zone, in which a heater is to increase a temperature of a printhead to a first temperature higher than or equal to about a steady state printing temperature; and a heating device to increase a temperature of the print zone such that a portion of a print medium disposed over a portion of a platen in the print zone is at a second temperature higher than or equal to about a steady state print zone temperature; wherein the printhead is to dispose an ink at the steady state printhead temperature onto the portion of the print medium to form an image thereon.
To the extent applicable, the terms “first,” “second,” “third,” etc. herein are merely employed to show the respective objects described by these terms as separate entities and are not meant to connote a sense of chronological order, unless stated explicitly otherwise herein.
Printhead assembly 12 includes at least one fluid ejection device which eject drops of ink or fluid through a plurality of orifices or nozzles 13—e.g., at least one printhead. Only for the sake of convenience, “printhead” is used as a representative example of a fluid ejection device or even to represent the printhead assembly herein, but it is readily understood that other types of fluid ejection devices may be suitable. The printhead assembly 12 may comprise a heater (not shown) to increase the temperature of the printhead (or printhead assembly as a whole) to a predetermined temperature—this is discussed further below. This heater may comprise a warming device, which may comprise a heater transducer or a resistor. The heater may be employed to produce power pulses. In one example, each resistor is individually addressable to heat and vaporize ink in one of the plurality of channels. As voltage is applied across a selected resistor, a vapor bubble may grow in the associated channel and initially bulges from the channel orifice, followed by collapse of the bubble. The ink within the channel may then retract and separate from the bulging ink, to form a droplet moving in a direction away from the channel orifice and towards the recording medium. When the ink droplet hits the recording medium, a drop or spot of ink is deposited. The channel is then refilled by capillary action, which, in turn, draws ink from a supply container of liquid ink.
Through the ejection of drops of ink, the ink may dispose the ink onto a print medium (or a portion thereof). The disposing process, or “printing”, may be carried out at a specific condition (e.g., temperature) of the print zone. The steady state temperature may encompass the steady state printhead temperature (or “Tss,ph”) and the steady state print zone temperature (or “Tss,pz”). In one example, this is known as a steady state printing temperature. In one example, the ink is disposed over a print medium, such as a print medium 19, so as to form an image on the print medium 19. Print medium 19 may include any type of suitable sheet material, such as paper, card stock, transparencies, Mylar, fabric, and the like. In one example, nozzles 13 are arranged in at least one column or array such that properly sequenced ejection and disposition of ink from nozzles 13 may cause characters, symbols, and/or other types of graphics or images to be printed upon the print medium 19 as printhead assembly 12 and print medium 19 are moved relative to each other.
In this example, ink supply assembly 14 supplies ink to printhead assembly 12 and includes a reservoir 15 for storing ink. As such, in one example, ink flows from reservoir 15 to printhead assembly 12. In one example, printhead assembly 12 and ink supply assembly 14 are housed together in an inkjet or fluid-jet print cartridge or pen. In another example, ink supply assembly 14 is separate from printhead assembly 12 and supplies ink to printhead assembly 12 through an interface connection (e.g., a supply tube).
In this example, carriage assembly 16 positions printhead assembly 12 relative to print media transport assembly 18 and print media transport assembly 18 positions print medium 19 relative to printhead assembly 12. The print media transport assembly may comprise a platen (not shown). In one example, the platen is a stationary platen to extend under and support the print medium 19 in close proximity to the printhead in the print zone 17 as the print medium 19 is drawn along an advancement direction. A print zone 17 herein may be defined as an area adjacent to nozzles 13 between and including printhead assembly 12 and print medium 19. In one example, printhead assembly 12 is a scanning type printhead assembly such that carriage assembly 16 moves printhead assembly 12 relative to print media transport assembly 18. In another example, printhead assembly 12 is a non-scanning type printhead assembly such that carriage assembly 16 fixes printhead assembly 12 at a prescribed position relative to print media transport assembly 18.
In this example, the printing apparatus may further comprise a heating device 21. The heating device may be employed to increase the temperature of the print zone 17 such that a portion of a print medium 19 disposed over a portion of a platen (in the print media transport assembly 18) in the print zone is at a second temperature higher than or equal to about a steady state print zone temperature. In some instances, the heating of the print zone by the heating device 21 allows both the portion of the portion medium and the portion of the platen in the print zone to be both at the second temperature. In one example, the heating of the print zone by the heating device 21 allows the entire print medium and/or the entire platen to be at the second temperature.
A printing apparatus may further comprise servicing components. For example,
In the printing apparatus as shown in
Electronic controller 22 receives data 23 from a host system, such as a computer, and may include memory for temporarily storing data 23. Data 23 may be sent to inkjet printing system 10 along an electronic, infrared, optical or other information transfer path. Data 23 represents, for example, a document and/or file to be printed. As such, data 23 forms a print job for inkjet printing system 10 and includes one or more print job commands and/or command parameters.
In one example, electronic controller 22 provides control of printhead assembly 12 including timing control for ejection of ink drops from nozzles 13. As such, electronic controller 22 defines a pattern of ejected ink drops which form characters, symbols, and/or other graphics or images on print medium 19. Timing control and, therefore, the pattern of ejected ink drops, is determined by the print job commands and/or command parameters. In one example, logic and drive circuitry forming a portion of electronic controller 22 is located on printhead assembly 12. In another example, logic and drive circuitry forming a portion of electronic controller 22 is located off printhead assembly 12. The electronic controller 22 also may provide control of heating the heater in the printhead assembly 12 and/or the heating device 21, such as according to a predetermined preconditioning protocol.
Trickling warming in one example is described as follows: To reduce the effect of temperature variance from the beginning of printing to another point in the printing process, a warming device, such as the heater in the printhead assembly described above, may be employed. A warming device is used to raise the temperature of the printhead. The printhead assembly may include a mechanism to control the electrical current to the firing resistors so that their energy is below the threshold to eject an ink drop. This mechanism may communicate with an electrical controller, such as that shown in
Trickle warming may be carried out by a preconditioning algorithm or routine and be executed in various ways. For example, trickle warming may have a cascading way of different trickle warming settings. One example of a cascading way of different trickle warming settings may include incremental increase of printhead temperature until the desired predetermined temperature is reached. The duration of each increment may have any suitable value. Additionally, trickle warming may have fixed trickle warming settings. For example, fixed trickle warming settings may involve a one-step increase of the printhead temperature of the desired temperature. The desired temperature, or “first temperature,” as shown in S201, may be higher than or equal to about the steady state printhead temperature. As discussed below, the term “equal to” about the steady state temperature may encompass the situations of both being “equal to” and “slightly lower than.”
A steady state printhead temperature (“Tss,ph”) may refer to the temperature of the printhead during printing, the peaks of which temperature profile (which may be oscillating) have remained at least substantially constant (within ±3° C.) for a certain period of time (of any suitable value)—e.g., 1 min, 2 min, etc. The steady state printhead temperature may have any suitable value, depending on the system and parameters employed. For example, the steady state printhead temperature may be between about 35° C. and about 75° C.—e.g., between about 40° C. and about 75° C., between about 45° C. and about 65° C., between about 50° C. and about 60° C., etc. Other values are also possible.
The preconditioning may further comprise increasing a temperature of the print zone such that a portion of a print medium disposed over a portion of a platen in the print zone is at a second temperature higher than or equal to about a steady state print zone temperature.
A steady state print zone temperature (“Tss,pz”) may refer to the temperature of the print zone during printing, the lowest values of which temperature profile (which may be oscillating) have remained at least substantially constant (within ±1° C.) for a certain period of time (of any suitable value)—e.g., 1 min, 2 min, etc. The steady state print zone temperature may have any suitable value, depending on the system and parameters employed. For example, the steady state print zone temperature may be between about 15° C. and about 55° C.—e.g., between about 20° C. and about 50° C., between about 25° C. and about 45° C., between about 30° C. and about 40° C., etc. Other values are also possible.
The temperature of the print zone may be increased by any suitable techniques. For example, it may involve heating, using an energy source (e.g., the heating device as shown in
The increasing of the temperature of the inkjet printhead and the increasing of the temperature of the print zone may take place in sequence (of any suitable order) or in parallel. Because of the different processes involved, the preconditioning process may take any suitable amount of time. For example, the preconditioning may be completed less than or equal to about 10 minutes—e.g., less than or equal to about 8 minutes, about 6 minutes, about 5 minutes, about 4 minutes, about 3 minutes, about 2 minutes, or shorter. Other lengths of time are also possible.
As further shown in
Various examples described herein may be implemented at least in part as a non-transitory machine-readable storage medium (or multiple machine-readable storage media)—e.g., a computer memory, a floppy disc, compact disc, optical disc, magnetic tape, flash memory, circuit configuration in Field Programmable Gate Arrays or another semiconductor device, or another tangible computer storage medium or non-transitory medium) encoded with at least one machine-readable instructions that, when executed on at least one machine (e.g., a computer or another type of processor), cause at least one machine to perform methods that implement the various examples of the technology discussed herein. The computer readable medium or media may be transportable, such that the program or programs stored thereon may be loaded onto at least one computer or other processor to implement the various examples described herein.
The term “machine-readable instruction” is employed herein in a generic sense to refer to any type of machine code or set of machine-executable instructions that may be employed to cause a machine (e.g., a computer or another type of processor) to implement the various examples described herein. The machine-readable instructions may include, but are not limited to, a software or a program. The machine may refer to a computer or another type of processor specifically designed to perform the described function(s), when executed to perform the methods described herein, the machine-readable instructions need not reside on a single machine, but may be distributed in a modular fashion amongst a number of different machines to implement the various examples described herein.
Machine-executable instructions may be in many forms, such as program modules, executed by at least one machine (e.g., a computer or another type of processor). Generally, program modules include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. Typically, the operation of the program modules may be combined or distributed as desired in various examples.
Employing the apparatus and method described herein may help reduce, or even minimize, the challenges faced with printing a long print job (e.g., several meters) described herein. For example, the method, particularly the preconditioning, would take a small amount of time, relatively to some of the pre-existing methods. The print medium waste may also be reduced, as described above. In one example, the printing method described herein need not involve a primer plot. Further, the color consistency may be higher than pre-existing techniques.
The color consistency may be described using any suitable metrics. One example of such a metric is delta E. Delta E is an industry standard defined by International Commission of Illumination (“CIE”). Delta may be calculated based on the Euclidian distance between two points in a three dimensional space. This space in this case is the LAB color space. Specifically, delta E (“ΔE”) may be calculated by:
where a hue rotation term (RT) is to deal with the problematic blue region (hue angles in the neighborhood of 275°); compensation for neutral colors (the primed values in the L*C*h differences); compensation for lightness (SL); compensation for chroma (SC); and compensation for hue (SH). The kL, kC, and kH are usually unity. The definition of delta E in this example is explained in the standard CIEDE2000 by CIE.
The value of delta E in the printed article (e.g., printed print medium) may have any suitable value, depending on the apparatus and process parameters employed. Such a delta E may have a value lower than one resulted from a printing method not as described herein, particularly one without the preconditioning. For example, for a certain length the image formed by the method described herein may be at least about 10%—e.g., at least about 20%, about 30%, about 40%, or more, lower than one formed by a printing method otherwise without the preconditioning. Other values are also possible. The length may be between about 20 m and about 60 m—e.g., between about 30 m and about 50 m, between about 35 m and about 45 m, etc. Other values are also possible. In one example, the length is about 45 m.
Not to be bound by any particular theory, but the benefits of the printing method described herein may be explained as follows: two factors may affect the color consistency in the long job: ink drop size difference along the slowly warming up of the printheads during the long job and ink-medium interaction difference when the printing apparatus is cold or warm. In one example, at the beginning of printing, because the printheads and the printing apparatus as a whole are cold, the color is deviated that from the steady state condition. However, once the system enters the steady state, the color difference is much less. The temperature difference thus results in color inconsistency. The method descried herein may mitigate this difference. For example, the preconditioning of the printhead may allow the base temperature of the printheads to reach to the similar level as the steady state before printing commences. Also, the preconditioning of the print zone may allow the print medium and platen to approach to the steady state earlier, thereby assuring a more uniform temperature along the long job.
It should be appreciated that all combinations of the foregoing concepts (provided such concepts are not mutually inconsistent) are contemplated as being part of the inventive subject matter disclosed herein. In particular, all combinations of claimed subject matter appearing at the end of this disclosure are contemplated as being part of the inventive subject matter disclosed herein. It should also be appreciated that terminology explicitly employed herein that also may appear in any disclosure incorporated by reference should be accorded a meaning most consistent with the particular concepts disclosed herein.
The indefinite articles “a” and “an,” as used herein in this disclosure, including the claims, unless clearly indicated to the contrary, should be understood to mean “at least one.” Any ranges cited herein are inclusive.
The terms “substantially” and “about” used throughout this disclosure, including the claims, are used to describe and account for small fluctuations, such as due to variations in processing. For example, they may refer to less than or equal to ±5%, such as less than or equal to ±2%, such as less than or equal to ±1%, such as less than or equal to ±0.5%, such as less than or equal to ±0.2%, such as less than or equal to ±0.1%, such as less than or equal to ±0.05%.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2015/059193 | 11/5/2015 | WO | 00 |
