Patent Application
20140292843
Some printing systems form a printed image by ejecting printing fluids from printheads. Thereby, printing fluids, such as treatment fluids and inks, are applied onto a print medium for printing a pattern of individual dots at particular locations. The printed pattern reproduces an image on the printing medium. At least some of these printing systems are commonly referred to as inkjet printers.
A treatment fluid may be used for enhancing print quality of a printed pattern. For example, a pre-treatment fluid (e.g., a fixer) may be applied on a substrate location prior to ink deposition for addressing coalescence, bleed, feathering, or similar effects caused by ink or pigment migration across the printed surface. Alternatively, or in addition thereto, a post-treatment fluid (e.g. a coating), may be applied on a substrate location after ink deposition for protecting the printed pattern.
Common methods for applying a treatment fluid include roll coating, spray coating, manual application or treatment ejection.
In order that the present disclosure may be well understood, various examples will now be described with reference to the following drawings.
In the following description, numerous details are set forth to provide an understanding of the examples disclosed herein. However, it will be understood that the examples may be practiced without these details. While a limited number of examples have been disclosed, it should be understood that there are numerous modifications and variations therefrom. Similar or equal elements in the Figures may be indicated using the same numeral.
An image may be reproduced on a substrate by printing a pattern of individual dots. Inkjet printers print dots by ejecting very small drops of ink onto the print medium via one or more printheads each having ink ejecting nozzles as set forth below with respect to
Print quality is one of the most important considerations in printing. Since the image output of an inkjet printer is formed of thousands of individual ink drops, the quality of the image is dependent upon the quality of each ink drop and the arrangement of the ink drops on the print medium.
One common problem that may degrade quality of a printed image is ink migration across the substrate onto which it is deposited. This might cause a lack of edge sharpness. In an ideal environment, ink drops would form a perfect circle of uniform size when applied to a medium. However, it is common for ink drops to bleed or feather into surrounding areas when applied to a medium. If the surrounding area is a non-ink area, then the resulting image will not have a well-defined edge. If the surrounding area is another ink drop, then the colors of the two ink drops may combine, producing a different undesirable color. In either case, the quality of the image may be seriously degraded. The printing artifacts may be respectively referred to as bleeding and feathering.
Ink migration may cause other artifacts such as coalescence, in which ink droplets on the substrate may merge. Merged ink droplets may form pools and puddles that, when drying, may cause visible non-uniformities.
Another common problem that may affect printing is slow drying of ink. For example, after printing of a page is complete, the printer may need to hold a page for letting the ink drying before depositing the page in an output tray. This may place an undesirable limit on how fast consecutive pages can be printed.
Another problem that may appear is poor water fastness. After ink dries on a substrate, it might be desirable to maintain the integrity of the image even if a small amount of moisture, such as perspiration from one's hand, is applied to the image. If the image has poor water fastness, moisture may cause the ink to bleed or run, thereby seriously degrading the printed image.
Another problem that may appear once an inked pattern is printed on substrate is susceptibility to scratches or rubbing that may degrade print quality.
For addressing the above problems, some approaches have been employed.
One approach is to use special inks that will either react with each other or with the medium to improve edge sharpness and ink adherence to the substrate. This approach, however, severely restricts the types of inks that can be used in inkjet printing systems. Another approach is to use special media that promotes fast adherence of inks thereto. This approach may be very restrictive since special media (e.g., specially purchased paper) may be required when printing with a desired print quality.
Another approach for addressing the above problems is to use a treatment fluid. For example, via a treatment fluid, fixer may be applied on inked dots. The fixer may prevent ink to spread beyond locations where it is deposited. Fixer deposition for addressing bleeding and/or feathering may include blooming in order to add robustness against printer misalignment. By blooming fixer is also applied to substrate locations surrounding inked dots. Other treatment fluids may be used. For example a coating may be applied on inked dots to address at least some of the above problems or to provide a protecting coating to a printed pattern.
Applying treatment to a substrate may, however, cause some undesirable effects. Applying too much treatment to each dot location can cause the medium to warp or cockle. Using too much treatment may also unacceptably increase print costs. On the other hand, using too little treatment may not achieve the desired print quality and, more specifically, negatively affect some printing output parameters such as, chroma, water fastness, strike through avoidance, and edge sharpness.
In order to address problems related to treatment application, it has been elsewhere proposed to apply on a substrate location a variable amount of treatment, the treatment amount depending on a quantity of ink to be applied to the substrate location. However, variable treatment application may not be efficient at high ink densities since there deposition of treatment beyond a certain amount may not convey any substantial improvement in print quality.
It has also been proposed to apply a constant amount of treatment. However, at low ink densities, the percentage of deposited treatment relative to deposited ink may be too high resulting in deposition of more treatment that actually required. This might result on unnecessary waste of treatment and/or undesired effects due to the relatively high amount of treatment relative to ink.
In at least some of the examples herein, printing methods are disclosed that facilitate an efficient deposition of treatment. For substrate locations with a relatively low ink density, a treatment is variably applied in order to avoid an excess of treatment fluid. This might be seen as a variable treatment-to-ink regime. Blooming may be omitted at the relatively low ink densities since, for those ink densities, bleeding and/or feathering may not be perceivable.
On the other hand, for substrate locations with a relatively high ink density, an efficient treatment usage may be provided by applying a constant treatment amount (this might be seen as a constant treatment-to-ink regime) and combining it with blooming. A constant treatment amount refers to applying an amount of treatment irrespective of how much the ink amount exceeds the threshold. Blooming, as used herein refers to depositing treatment on dot locations surrounding a dot location identified to receive a certain amount of ink. Blooming may be restricted to substrate dot locations that are not determined to receive ink. Further, printing may be performed such that all substrate dot locations to receive treatment via blooming are to receive the same amount of treatment. In other examples, blooming is not restricted to substrate dot locations that are not determined to receive ink.
Such examples combine the benefits of (1), applying treatment variably, i.e., with a treatment amount adapted to the local ink conditions, and (2) constantly applying treatment using blooming for robustness. Further, such examples consider when one of these approaches conveys the most benefits. More specifically, such examples facilitate an efficient usage of treatment by taking into account a threshold that determines when using one of approaches (1) or (2) is more effective. Further, such a treatment application can be implemented in a computational efficient manner. It should be taken into account that due to required print speeds, computational capabilities for determining treatment application may be significantly limited.
The following description is broken into sections. The first, labeled “Environment,” describes environments in which examples may be implemented. The second section, labeled “Components,” describes various physical and logical components for implementing various examples. The third section, labeled a “Operation,” describes steps taken to implement various embodiments.
E
As shown in the diagram, printer 100 includes a carriage 102 with a printhead receiving assembly 104. In the illustrated example, printer 100 is illustrated including printhead 106 in printhead receiving assembly 104. Carriage 102 is to transition printhead 106 across the width of a substrate 108, i.e., along printhead transition directions 110, 112. For example a drive 146 may be coupled to carriage 102 for effecting carriage transition. Thereby, printer 100 can perform printing across a width of substrate 108 via translation of carriage 102. In other examples, printhead 106 is a page-wide array printhead and translation is not required for printing across a width of substrate 108.
Printhead 106 in this example is illustrated to include a plurality of ink printhead units 114, 116, 118, 120. Each of the ink printhead units is configured to eject ink 122 of a different color via respective ink nozzle array arrangement 124, 126, 128, 130. Ink printhead units 114, 116, 118, 120 are fluidly connected to an ink reservoir system 132. Ink reservoir system 132 includes ink reservoirs 132a, 132b, 132c, 132d for providing ink to the respective ink printhead units. In the illustrated example, ink reservoirs 132a, 132b, 132c, 132d respectively store cyan ink, magenta ink, yellow ink, and black ink.
Base colors may be reproduced on substrate 108 by depositing a drop of one of the above mentioned inks onto a substrate location. Further, secondary colors can be reproduced by combining ink from different ink printhead units. In particular, secondary or shaded colors can be reproduced by depositing drops of different base colors on adjacent dot locations in the substrate location (the human eye interprets the color mixing as the secondary color or shading). It will be understood that further ink reservoirs may be provided. For example, a CcMmKY system may include further ink reservoirs for light cyan (c) and light magenta (m).
According to some examples herein, printer 100 may include at least one printhead unit for ejecting a pre-treatment fluid 146a and/or at least one printhead unit for ejecting a post-treatment fluid 146b. In the example of
Treatment printhead unit 134 is for applying a post-treatment 146b (e.g., a coating) on the substrate location via a post-treatment nozzle arrangement 142. A post-treatment may be as described by U.S. patent application Ser. No. 12/383,066 published under publication number US 2012/0120142.
The block diagram in
It will be appreciated that examples can be realized with any number of printhead units depending on the design of the particular printing system, each printhead unit including a nozzle array for jetting a printing fluid such as ink or treatment. For example, printer 100 may include at least one treatment printhead unit, such as two or more treatment printhead units. Furthermore, printer 100 may include at least one ink printhead unit, such as two to six ink printhead units, or even more ink printhead units.
In the illustrated examples, ink printhead units are located at one side of a treatment printhead. It will be understood that ink printheads may be located at both sides of a treatment printhead. Further, printhead units might be monolithically integrated in printhead 106. Alternatively, each printhead unit might be modularly implemented in printhead 106 so that each printhead unit can be individually replaced. Further, printhead 106 may be a disposable printer element or a fixed printer element designed to last for the whole operating life of printer 100.
Printer 100 further includes a controller 148, which is operatively connected to the above described elements of printer 100. Controller 148 is shown configured to execute a print job received from a printout source 150 according to control data 105. Via control data 105 it might be determined whether, for one or more substrate location, how treatment fluid is to be ejected, e.g. whether according to a variable treatment-to-ink regime or to a constant treatment-to-ink regime. Control data 105 may be generated based on data for print job source 150. Further, control data 105 may be generated by print job source 150 and provided to controller 148. Controller 148 is shown to include processor 154. Processor 154 is configured to execute methods as described herein. In some examples, printer 100 includes an application-specific integrated circuit (ASIC) configured to generate control data 105 as illustrated by examples herein.
Processor 154 may be implemented, for example, by one or more discrete modules (or data processing components) that are not limited to any particular hardware, firmware, or software (i.e., machine readable instructions) configuration. Processor 154 may be implemented in any computing or data processing environment, including in digital electronic circuitry, e.g., an application-specific integrated circuit, such as a digital signal processor (DSP) or in computer hardware, firmware, device driver, or software (i.e., machine readable instructions). In some implementations, the functionalities of the modules are combined into a single data processing component. In other versions, the respective functionalities of each of one or more of the modules are performed by a respective set of multiple data processing components.
Memory device 152 is accessible by controller 148 and, more specifically, by processor 154. Memory device 152 may be integrated within controller 148 or may be a separate component communicatively connected to controller 148. Memory device 152 stores process instructions (e.g., machine-readable code, such as computer software) for implementing methods executed by controller 148 and, more specifically, by processor 154.
Program instructions in memory device 152 may be part of an installation package that can be executed by processor 154 to implement control engine 108. In this case, memory 152 may be a portable medium such as a CD, DVD, or flash drive or a memory maintained by a server from which the installation package can be downloaded and installed. In another example, the program instructions may be part of an application or applications already installed. Here, memory 152 can include integrated memory such as a hard drive. It should be noted that a tangible medium as used herein is considered not to consist of a propagating signal. In examples, the medium is a non-transitory medium.
Controller 148 receives print job commands and data from print job source 150, which may be a computer or any other source of print jobs, in order to print an image based on a print mask. The received data may include treatment control data 105. A print mask refers to logic that includes control data determining which nozzles of the different printheads are fired at a given time to eject fluid in order to reproduce a print job. The print mask may be processed according to control data 105 by processor 154 in order to cause ejection of treatment according to examples herein. In an example, control data 105 forms part of a print mask supplied by print job source 150. Alternatively, control data 105 might be implemented in the print mask by a pre-processing performed by processor 154, or any other processor, so that treatment is ejected as disclosed herein.
Controller 148 is operatively connected to treatment printhead units 134, 136, ink printhead units 114, 116, 118, 120, and the respective reservoirs to control, according to the print mask and the control data in memory 152. Thereby, controller 148, and more specifically processor 154, can control functionality of printer 100 such as, but not limited to printing according to control data 105.
It will be understood that the functionality of memory 152 and print job source 150 might be combined in a single element or distributed in multiple elements. Further, memory 152 and print job source 150 may be provided as external elements of print system 100. Further, it will be understood that operation of processor 154 to control treatment ejection is not limited to the above examples.
C
In the example of
Program instructions in memory 152 may be part of an installation package that can be executed by processor 154 to implement examples herein. In this case, memory 152 may be a portable medium such as a CD, DVD, or flash drive or a memory maintained by a server from which the installation package can be downloaded and installed. In another example, the program instructions may be part of an application or applications already installed. Here, memory 152 can include integrated memory such as a hard drive. It should be noted that a tangible medium as used herein is considered not to consist of a propagating signal. In examples, the medium is a non-transitory medium.
In
Treatment determination module 202 is configured to determine how treatment fluid is to be deposited. Treatment determination module 202 may be configured to process treatment ejection data that specifies operation of a treatment printhead. For example, treatment determination module 202 may merely process treatment control data 105 (illustrated above with respect to
For generating control data 105, module 202 may access look-up tables 208, stored in data store 206. Look-up tables 208 may be designed to transform image data (e.g., RGB data 602a-602c shown in
Treatment application module 204 is configured to cause a printer, e.g., printer 100 in
O
At block 302, an image to be printed is processed. The processing at block 302 may include receiving image data 602 to be printed by printer 100. The image data may be provided by a computing system externally connected to printer 100 via a physical connection (e.g., a USB cable or the like), or a wireless connection (via a wireless local area network). Image data may be comprised of a set of rot, green, blue (ROB) values for each pixel on the image (e.g., image data 602 shown in
In the present description, a substrate dot location is understood as an area of a substrate onto which a pixel of an image is to be reproduced.
Referring back to
At block 306, the ink amount determined at block 304 is compared to a threshold to determine a treatment-to-ink regime.
In examples herein, the threshold is an ink amount limit that may be pre-determined based on one or more factors. Generally the threshold is pre-determined as the ink amount limit above which depositing a constant treatment amount and blooming is sufficient to satisfy certain print quality requirements. In such examples, below the pre-determined ink amount limit blooming may not provide any significant advantage and a proportional deposition of amount of ink facilitates an efficient usage of treatment.
In general, a trial-and-error approach may be used to determine a threshold that is suitable for a required print quality requirement. For example, the threshold may be determined via experimentation by printing test patches using different ink amounts. The printed test patches may be a sequence that starts with a low ink amount and successively increases ink amounts. For printing the test patches, variable and constant treatment-to-ink regimes may be interleaved. Thereby, it might be assessed ink amounts for which print quality is satisfactory or not for different treatment-to-ink regimes.
Alternatively, or in addition thereto, the above procedure may be performed varying print parameters (e.g., used inks, substrates, or printing conditions such as temperature or humidity). Thereby, a threshold may be determined specific to certain print parameters such as printing conditions, used inks, or used substrates. It will be understood that a value of the threshold may be pre-determined in a number of manners.
In an example, if the treatment fluid includes a fixer, above the pre-determined threshold (for example, an ink amount limit between 1 and 4 drop-per-pixels, dpp, such as 2 dpp), applying a constant fixer amount is determined to be sufficient for controlling ink migration; further, below the pre-determined threshold, applying bleeding is determined not to convey a significant advantage since the low ink amount to be deposited does not cause a significant bleeding effect; further, below the pre-determined threshold, applying a variable fixer (e.g., a fixer amount proportional to ink to be deposited) is determined to be a more efficient usage of treatment.
Referring back to
In the example illustrated in
If at block 306 it is assessed that the ink amount is not below the threshold, then process flow 300 goes to blocks 312 and 310 where printer operation control data 105 for applying treatment according to a constant treatment-to-ink regime is generated. A constant treatment-to-ink regime includes applying bloom in dot locations surrounding the first dot location.
In a constant treatment-to-ink regime, a selected constant treatment amount is deposited. In other words, for any amount of ink exceeding the threshold, the same treatment amount is deposited on the substrate dot location. The selected constant treatment amount to be deposited when the ink amount is above a threshold is, generally, a treatment amount that is sufficient to address issues caused by ink mobility. In an example, the selected constant treatment amount is a maximal treatment amount. The maximal treatment amount may be determined by the capacity of printer 100 to deposit treatment during a pass over the substrate location for printing on a single dot. Printer 100 may be designed so that maximal treatment amount is a certain percentage of the maximal amount of ink that can be deposited on a single substrate location, e.g. a percentage between 5 and 15% of the maximal ink amount such as 8%.
There are a variety of options for applying blooming. Some examples on how blooming may be applied are illustrated in, for example, U.S. Pat. No. 6,598,965, which is incorporated herein by reference in its entirety (to the extent in which this document is not inconsistent with the present disclosure) and in particular those parts thereof describing blooming. In some example, in the constant treatment-to-ink regime, the same treatment amount is to be applied to the first dot location and to dot locations surrounding the first dot location used at block 304 onto which blooming is applied.
Process flow 300 illustrates treatment deposition onto a single substrate dot location. It will be understood that process flow 300 may be extended for generating control data for all substrate dot locations that are to be printed for reproducing a complete image. Thereby, complete sets of data might be generated that determines where and how treatment is to be applied. Printer 100 may address these data sets to apply treatment for reproducing a complete image on a substrate.
It will be understood that there are a variety of options for generating printer operation control data. Some examples for generating control data for applying treatment on a substrate are illustrated in, for example, U.S. Pat. No. 6,598,965, which is incorporated herein by reference in its entirety (to the extent in which this document is not inconsistent with the present disclosure) and in particular those parts thereof describing circuits for treatment data generation.
Control data generation may imply generating one or more treatment planes indicating printing system 100 where to apply treatment. Such examples of control data generation are illustrated in the following with respect to
The basis for control data generation is image data 602. Image data 602 is comprised of a plurality of pixels, each pixel having associated thereto a RGB value. Therefore, image data 602 can be seen as being comprised of three color planes: a red (R) plane 602a, a green (G) plane 602b, and a blue (B) plane 602c. Image data 602 may be color converted to generate color planes corresponding to the color gamut of printer 100. For example, a color conversion 606 may be used to transform the RGB planes 602a-602c into CMYK planes 604a-604d. Each CMYK plane may be comprised of ink amount values to be applied on substrate dot locations for reproducing the image associated to image data 602. If the printer includes further ink channels (e.g., a light cyan and/or a light magenta channel), further corresponding planes may be generated.
There are a variety of options for storing ink amount values in CMYK planes 604a-604d. For example, ink amount values may be stored as 8 bit values associated to specific substrate dot locations. These ink amount values can then be used as input values for printhead units 114, 116, 118, 120 when positioned over the corresponding substrate dot locations.
Color conversion 606 is configured depending on the specific requirements of the particular printing systems. For example, color conversion 606 may be comprised of look-up tables (e.g., look-up tables 208 shown in
Ink amounts to be deposited on substrate dot locations can be derived from CMYK planes 604a-604d and used to build one or more treatment planes for determining where and under which treatment-to-ink regime a treatment printhead unit (e.g., any of treatment printhead units 134 and 136 shown in
These deposition units refer to treatment deposition units that are separately addressable for deposition of treatment. For example, as illustrated by
Referring back to
In an example, if the ink amount associated via CMYK planes 604a-604d to a substrate dot location is below a threshold (e.g., 2 dpp), the treatment in a corresponding location in plane T1 is set to be proportional to the ink amount. If the ink amount associated via. CMYK planes 604a-604d to a substrate dot location exceeds the threshold, the treatment in a corresponding location in plane T1 is set to a maximum value possible. Then halftoning may be performed at the threshold value, so that T1 is comprised of (1) areas with low half-toned values (e.g. 0 or 1), where ink is low and treatment is to be applied proportional to ink, and (2) areas with high half-toned values (e.g. 3), where ink is above the threshold, and treatment is to be applied under a constant treatment-to-ink regime. T1 may be then processed using a special mask (e.g., using a LUT), so that the half-toned values are printed.
The resulting plane T1 may be addressed by a further transform 610 for generating a second treatment plane T2 for causing a second treatment deposition unit to deposit treatment in bloomed locations surrounding locations associated with the constant treatment-to-ink regime. Transform 610 may populate second treatment plane T2 for blooming areas in first treatment plane T1 that correspond to a constant treatment-to-ink regime.
Each of the resulting planes T1 and T2 are then to be printed with a different trench 702 or 704 in treatment print units 134, 136. Thereby, a computationally efficient generation of treatment can be implemented via the generation of multiple treatment planes. It will be understood that there are other options for generation the treatment deposition data. For example, a single treatment plane can be built by combining each of the resulting planes T1 and T2. Such a single treatment plane can then be used to operate a single treatment deposition unit implementing both treatment-to-ink regimes.
In the following, treatment deposition is illustrated with respect to
At block 402, control operation data 105 is processed. For example, data generated via process flow 300 may be accessed and made readily available to controller 148 for operation of one or more of treatment printhead units 134, 136 in
As represented by block 404, the manner on which treatment application is applied depends on whether an ink amount to be applied on a substrate dot location 504 is above or below the threshold mentioned above.
If the ink amount to be deposited in a substrate dot location is below a threshold, the selected treatment-to-ink regime includes depositing at block 406 an amount of treatment in that substrate dot location. In the specific example of
If the ink amount to be deposited in a substrate dot location is above the threshold, the selected treatment-to-ink regime includes depositing at block 408 a selected constant amount of treatment in the substrate dot location. Further, block 407 also includes blooming in an area surrounding the specific substrate dot location.
Treatment deposition according to flow chart 400 is graphically illustrated in
In this example, as shown in graph 800, 802, at variable treatment-to-ink regime 806, the amount of treatment to be deposited for low ink amounts (i.e., below threshold 804 at 2 dpp) is proportional to the ink amount. In the example, this proportionality is set to a fixed percentage of 12%. Such a variable treatment-to-ink regime facilitates that an efficient treatment is performed while preventing that too much treatment is applied at very low ink amounts.
Further, at constant treatment-to-ink regime 806, the amount of treatment to be deposited for high ink amounts (i.e., above threshold 804 at 2 dpp) is constant. Such a variable treatment-to-ink regime facilitates that an efficient treatment is performed for high ink amounts since, there, higher treatment might not provide substantial improvements in print quality, in particular in view of application of blooming to surrounding substrate dot locations. Further, it can be understood from
C
It will be appreciated that examples above can be realized in the form of hardware, programming or a combination of hardware and the software engine. Any such software engine, includes machine-readable instructions, may be stored in the form of volatile or non-volatile storage such as, for example, a storage device like a ROM, whether erasable or rewritable or not, or in the form of memory such as, for example, RAM, memory chips, device or integrated circuits or on an optically or magnetically readable medium such as, for example, a CD, DVD, magnetic disk or magnetic tape. It will be appreciated that the storage devices and storage substrate are embodiments of a tangible computer-readable storage medium that are suitable for storing a program or programs that, when executed, for example by a processor, implement embodiments. Accordingly, embodiments provide a program comprising code for implementing a system or method as claimed in any preceding claim and a tangible or intangible computer readable storage medium storing such a program. A tangible computer-readable storage medium is a tangible article of manufacture that stores data. (It is noted that a transient electric or electromagnetic signal does not fit within the former definition of a tangible computer-readable storage medium.)
In the foregoing description, numerous details are set forth to provide an understanding of the examples disclosed herein. However, it will be understood that the examples may be practiced without these details. While a limited number of examples have been disclosed, numerous modifications and variations therefrom are contemplated. It is intended that the appended claims cover such modifications and variations. Further, flow charts herein illustrate specific block orders; however, it will be understood that the order of execution may differ from that which is depicted. For example, the order of execution of two or more blocks may be scrambled relative to the order shown. Also, two or more blocks shown in succession may be executed concurrently or with partial concurrence. Further, claims reciting “a” or “an” with respect to a particular element contemplate incorporation of one or more such elements, neither requiring nor excluding two or more such elements. Further, at least the terms “include” and “comprise” are used as open-ended transitions.
