Patent Application
20100309489
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1. Field of the Disclosure
The present disclosure relates generally to media processing devices, and more particularly, to mechanisms for printing raster data in the media processing devices.
2. Description of the Related Art
Media processing devices such as a printer, a photocopier, and the like are commonly used in personal, official or other applications. The media processing devices, specifically printers, are extensively used for printing documents, stored in an electronic form on physical print media such as paper. A typical printer, such as an inkjet printer operates by directing a stream of minute ink droplets onto the paper so as to produce a final image on the paper. The ink is directed through nozzles configured on a printhead (PH) of the printer.
Generally, the printer is used as a peripheral device that is hosted by a system such as personal computer (PC) or any other controller device. The system may provide a data to the printer to print on the physical print media. The data can be in any form such as, but not restricted to, a textual data and an image. The data may be stored in a memory of the printer. The printer may start executing a print operation for a portion of the data, which is interpreted by a processor of the printer.
The data can be a raster data such as a scanned image or a photograph. The raster data includes a grid of cells for storing the data. The smallest discrete unit of the raster data in the grid is denoted by a pixel that displays a unique attribute of the smallest discrete unit. The printer carries out processing of the raster data for obtaining pixel information of the raster data for printing purpose. The pixel information provides information, about the smallest discrete component of the raster data, which is used for printing. The printer may eject ink on the physical print media for each pixel of the raster data in order to provide an impression to each pixel of the raster data. By providing color to each pixel of the raster data, the raster data may be printed on the physical print media. A line drawn in a raster format can be defined by a group of pixels along the length of the line. The group of pixels forms a raster line, and the raster data may be considered as including a plurality of raster lines.
Conventionally, the printer uses a swath-by-swath approach for printing the raster data. A band of ink drops printed at a time is generally referred to as the “swath.” The raster data is printed on the physical print media by performing printing in successive swaths. The printer may print the raster data in various ways such as one pass printing, multi-pass printing, etc. In one pass printing, each horizontal motion of the printhead across the print medium is used to print a portion of the raster data in one single scan. Multi-pass printing is employed by printing overlapping swaths having a partial printing density in each pass, in a process known as “shingling.”
Further ways of printing include 1-pass bidirectional (single pass in both the directions (left to right and right to left) of the raster data), multi-pass bidirectional printing such as 2-pass bidirectional (two passes in both the directions of the raster data), printing with slower carrier speed, etc. For example, black text may be printed by utilizing 1-pass bidirectional printing, and colored images may be printed by utilizing multi-pass bidirectional printing.
Typically, printing of the raster data may lead to various defects irrespective of the ways of printing. Conventionally, such defects occur at a swath boundary that may be due to blending of consecutive swaths together when a printhead of the printer scans the consecutive swaths. An example of such defects may be in form of a horizontal streak at the swath boundary. Such defects may yield poor quality of printed image on the physical print media Additionally, printing lines (especially vertical lines of the grid of the raster data) highlights any bidirectional differences in drop formation. More specifically, there may be differences in thickness of the printed image of the vertical lines in the bidirectional printing. Further, printing of high-density areas (i.e., bold or large texts) stresses nozzle usage of the printhead and causes additional defects such as misting, mottling, etc. Due to the defects described above, the user may need to choose from various predefined print options that may be available to the user, if the user encounters these defects while performing the printing. However, the user may be unable to avoid the trade-off between the printing speed and print quality related to the printing.
Based on the foregoing, there is a need for providing an optimized way for printing of the raster data in the media processing device so as to avoid the various printing defects and in order to maintain the printing quality. Further, there is a need for performing a print operation of the raster data with reduced effort and time requirements from the user's perspective.
In view of the foregoing disadvantages inherent in the prior art, the general purpose of the present disclosure is to provide a method for printing of raster data in a media processing device to include all the advantages of the prior art, and to overcome the drawbacks inherent therein.
In one aspect, the present disclosure provides a method for printing of raster data in a media processing device. The method includes identifying an attribute of a set of raster lines of the raster data. Further, the method includes determining at least one print mode from a plurality of print modes based on the attribute. Each print mode of the plurality of print modes is configured to print the set of raster lines of the raster data. Furthermore, the method includes printing the set of raster lines of the raster data in the at least one print mode.
In another aspect, the present disclosure provides a media processing device for printing of raster data. The media processing device includes a processing module and a printing module communicably coupled to the processing module. The processing module is configured to identify an attribute of a set of raster lines of the raster data. Further, the processing module determines at least one print mode from a plurality of print modes based on the identification of the attribute. The printing module is configured to print the raster data by printing the set of raster lines of the raster data. The printing module prints the set of raster lines of the raster data in the at least one print mode.
The above-mentioned and other features and advantages of this disclosure, and the manner of attaining them, will become more apparent and the disclosure will be better understood by reference to the following description of embodiments of the disclosure taken in conjunction with the accompanying drawings, wherein:
It is to be understood that the present disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The present disclosure is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. In this document, relational terms such as first and second, and the like may be used solely to distinguish one module or action from another module or action without necessarily requiring or implying any actual such relationship or order between such modules or actions. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless limited otherwise, the terms “connected,” “coupled,” “disposed” and “mounted,” and variations thereof herein are used broadly and encompass direct and indirect connections, couplings, and mountings. In addition, the terms “connected” and “coupled” and variations thereof are not restricted to physical or mechanical connections or couplings.
In addition, it should be understood that embodiments of the present disclosure include both hardware and electronic components or modules that, for purposes of discussion, may be illustrated and described as if the majority of the components were implemented solely in hardware. However, one of ordinary skill in the art, and based on a reading of this detailed description, would recognize that, in at least one embodiment, the electronic based aspects of the disclosure may be implemented in a software. As such, it should be noted that a plurality of hardware and software-based devices, as well as a plurality of different structural components may be utilized to implement the present disclosure.
The present disclosure provides a method for printing of raster data in a media processing device. The method is performed intelligently to optimize the printing by automating the process of recognizing various attributes related to the raster data, such as presence and absence of white spaces inside the raster data, and thereby avoids any printing defect. The method analyzes raster data and intelligently chooses to print text, including where to break the swath, which direction to print and how many passes are required for printing and thereby provides optimal performance for quality and speed.
The method works on the basis of various print modes that define one or more actions for printing the raster data. The raster data may consist of a set of raster lines. The print modes may provide information related to number of passes and direction of passes required to print the set of raster lines. The print mode further provides information about a particular subset of mono nozzles that may be utilized in the printing of the set of raster lines for optimizing nozzle usage in the media processing device. For example, the top nt (nt being an integral number) nozzles and the bottom nb (nb being an integral number) nozzles of a plurality of nozzles of the printhead (of the media processing device) may be utilized for printing on alternate swaths of printing of the set of raster lines. Alternatively, another subset of nozzles from a middle portion of the plurality of nozzles may be utilized for printing in order to maximize usage of each nozzle of the plurality of nozzles over time and thereby, to maintain nozzle health.
Referring now to the drawings and particularly to
Media processing device 100 may print the raster data by printing successive areas of the raster data in a sequential manner. The raster data may include a set of the raster lines and these lines are printed in a sequential manner in a swath-by-swath basis. Herein one swath of the printing represents an area of the set of raster lines that is printed in a single pass. The present disclosure provides processing of the raster data by the processing module 102 of media processing device 100 before actually printing the raster data on the physical print media.
Processing module 102 identifies an attribute of the set of raster lines of the raster data. The attribute of the set of raster lines of the raster data may include, but is not restricted to, a white space and a raster dot count. Further, processing module 102 may determine at least one print mode dynamically from a plurality of print modes on the basis of the identified attribute. The print mode may define an execution of various operations that are to be carried out in media processing device 100 in order to perform an efficient printing of the set of raster lines. The print mode may be utilized by printing module 104 by printing the set of raster lines in the print mode.
The print mode may define, but is not limited to, at least one of where to break the swath, number of passes required for printing, direction of passes for the printing, an index distance by which the printhead of media processing device 100 needs to be advanced between passes, and a number of nozzles of the printhead required for printing of the set of raster lines. The print mode for printing of the set of raster lines may be selected from the plurality of print modes based on the attribute of the set of raster lines. For example, if the set of raster lines (that are to be printed) includes a white space (the attribute of the set of raster lines), processing module 102 may determine a print mode from the plurality of print modes that defines a printing operation specifically for the presence of white space in the set of raster lines.
It would be apparent to those skilled in the art that processing module 102 may determine more than one print mode (from the plurality of print modes) for the set of raster lines on the basis of the plurality of attributes that are present in the set of raster lines. Printing module 104 prints the set of raster lines in the determined print modes.
Printing module 102 may print the set of raster lines by directing a stream of minute ink droplets onto the paper so as to produce an impression related to the set of raster data onto the physical print media. The ink is directed through nozzles configured on a printhead (PH) of the printer. Printing module 104 prints the set of raster data in the determined print modes of media processing device 100. A method for performing printing of the raster data in media processing device 100 is described in conjunction with
Referring now to
Method 200 starts at block 202. At block 204, method 200 identifies an attribute of a set of raster lines of a raster data. The attributes may include, but is not limited to, presence or absence of a white space and a raster dot count. In an embodiment, the presence or absence of white space may refer to presence or absence of white space at a particular raster line. Further, the raster dot count may denote a density or number of raster dots in the raster data. The white space at a particular raster line may be identified via blank or low value of the raster dot count at the raster lines. In one embodiment, if at the raster line, number of raster dot count is less than a particular threshold count, the presence of the white space may be determined at the raster line. The attribute of the set of raster lines may be determined by a processor of the media processing device, such as processing module 102.
At block 206, the method determines at least one print mode from a plurality of print modes based on the attribute. In one embodiment, the attribute may be compared with a predefined threshold value of the attribute to determine a print mode to print the set of raster lines. The print mode defines an action to be taken for printing the set of raster lines in successive swaths. Accordingly, different swaths of the set of raster lines may be printed with same or different print modes depending upon the identified attribute.
In one embodiment, the printing of the set of raster lines is performed in successive swaths. Method 200 selects a swath boundary by first analyzing an area of the set of raster lines that may be printed at a time. In a specific print mode, the swath boundary may be broken at a portion of the set of raster lines where the white space is identified. Selection of the swath boundary may also require that a number of nozzles of the printhead that are used for printing a particular swath should be more than a threshold number of nozzles. Accordingly, in this print mode, if the set of raster lines includes a white space (if the white space is present at a portion in the set of raster lines, i.e. the attribute of the portion of the set of raster lines is a white space) and the number of nozzles required for printing of the swath of the set of raster lines is greater than a threshold number of nozzles, such print mode of the plurality of print modes may be selected, which breaks the swath of printing at the portion of the set of raster lines where the white space is present. The threshold number of nozzles allows a limit to potential speed reduction of the printing if not all nozzles of the media processing device are used for the printing. In this print mode, it may be defined that the printing should be performed in a one-pass bidirectional printing of the swath. An example of such print mode is further explained in conjunction with
Further, in cases when the white space is not identified in the set of raster lines, at least one of a first print mode, a second print mode, and a third print mode of the plurality of print modes may be selected for the printing. The cases where the white space may not be present in an area of the set of raster lines include, but are not limited to, table border, a table with text, or a vertical line, or any continuous text spanning in more than one swath. Furthermore, the first print mode, the second print mode, and the third print mode may be utilized by the media processing device to mask any bidirectional defect and swath boundary defects. The bidirectional effect and the swath boundary defect are explained later in with reference to
The first print mode may include performing a two-pass bidirectional printing of the set of raster lines. The two-pass bidirectional printing may be performed by advancing the printhead of the media processing device by an index distance between passes of the two-pass bidirectional printing. For example; the two-pass bidirectional printing may be performed with a half (½) printhead media advance or a small (or no) media advance between passes. Further, in the second print mode, a one-pass unidirectional printing may be performed for one or more swaths of printing. More specifically, direction of the printing remains the same in successive swaths of printing in the second print mode.
The third print mode may include performing a one-pass bidirectional printing of the set of raster lines. The third print mode may be utilized for providing the fastest printing possible. It would be apparent to those skilled in the art that by performing the printing in a single pass and also in both directions in the third print mode provides a mode with an emphasis on print speed. Further, the one-pass bidirectional printing in the third print mode may utilize printing with at least a subset of nozzles from the plurality of nozzles in the case when there are visual defects associated with end nozzles of the printhead. Typically, such visual defects are associated with defective nozzles that should be found at the end of the printhead.
In one embodiment of the present disclosure, the first print mode, the second print mode and the third print mode may be used while placing the swath boundary in an area of the set of raster lines having the lowest number of raster dots and the number of nozzles used for printing the swath is greater than the threshold number of nozzles. This embodiment may be used for printing the raster data containing a table with text characters and thus avoiding a swath boundary within the text characters of the set of raster lines.
In another embodiment, the first print mode, the second print mode and the third print mode may be used while placing the swath boundary in an area of the set of raster lines having highest number of raster dots.
Further, the plurality of print modes includes a fourth print mode. The fourth print mode defines that printing of a particular area of the set of raster lines should be performed in a plurality of passes. The fourth print mode may be selected for the printing when the set of raster lines contains relatively large text. The media processing device may identify a large text (that can be fitted in a single swath) by identifying a number of contiguous raster lines in the set of raster lines of the raster data. Herein, the term ‘contiguous raster lines’ represent raster lines that share same attributes, such as same raster dot counts. For example, a text written in a bold pattern may have a number of dot counts greater than a threshold count in those raster lines that include at least a part of the text.
In one embodiment, such large texts that fit in a single swath can be identified on the basis of the number of contiguous raster lines that have raster dot counts greater than the threshold count. A presence of the large text is further shown and explained in conjunction with
At block 208, method 200 prints the set of raster lines of the raster data in the at least one print mode determined from the plurality of print modes. The set of raster lines may be printed in the media processing device by using a printing module, such as the printing module 104 (hereinafter referred to as “the printing module”). The set of raster lines may get printed in the determined print mode (as determined at block 206). The set of raster lines may be printed by utilizing the print mode from the plurality of print modes depending on primary errors such as the bidirectional defect and the swath boundary defect (that may be pre-defined) expected and/or the visibility of the primary errors in the printed output. More specifically, at least one print mode from the plurality of print modes may be identified for the printing of the set of raster lines depending upon the attributes of the set of raster lines.
Further, the printing of the set of raster lines based on the identified at least one print mode may require switching between the determined print modes based on attributes of the set of raster lines. Without limiting the scope of the present disclosure, in an example, when an area of very large text that spans more than one swath in the set of raster lines is printed according to the fourth print mode, and if the adjacent area of the large text also includes some part of the large text, the adjacent area will also be printed in the fourth print mode, even if the adjacent area has some other attributes such as presence of the white space in the adjacent area. However, it would be apparent to those skilled in the art that rules for switching between the modes for the printing of the set of raster lines may be customized.
Additionally, the printing may include text optimization through color printing. Typically, four different color inks (cyan, magenta, yellow, and black) are used by the media processing device to print the range of colors contained in the set of raster lines. A CMY nozzle (that represents cyan, magenta and yellow colors) usage can be dynamically optimized based on the monochrome (K) nozzle usage. For example, matching nozzle usage (i.e., use horizontally corresponding sets of nozzles for CMY and K) may be optimal. Alternatively, using a larger subset of CMY nozzles may results in optimal performance, which would be beneficial in areas of the set of raster lines where CMY drops are horizontally adjacent to the identified white space in the K areas of the set of raster lines.
The method 200 is terminated at block 210.
Similarly, next swath of the printing covers text line 7 to text line 12 of the raster data, and is performed as pass 2 in right to left direction, as shown in the
Further regarding pass 2, the print media is again advanced to align top of the printhead to next swath of the printing. Further, it may be determined that the white space is present below text line 13. However, the white space (below text line 13) is too short to be considered in a single swath of printing. Accordingly, a next pass (pass 3) may be considered from text lines 13 to 19 in one PH size (which may be a maximum swath height in a swath boundary) due to the presence of border 302. A next swath covering text lines 13 to 19 are scanned in pass 3 in left to right direction. Each of the plurality of nozzles of the printhead may be used in the pass 3. In
Solution to the swath boundary defect is further explained in conjunction with
Text lines 1 to 12 are printed in the same manner in pass 1 and pass 2, as explained in conjunction with
It may also be inferred that in such cases, the swath boundary is placed at an area of the raster data having minimum number of the raster dots before the raster line where swath boundary defect is likely to appear. Further, when more than one raster line includes the same minimum number of raster dots, a raster line among the more than one raster lines may be chosen, which may provide the largest print swath, i.e., print area coverage. However, in another embodiment of the present disclosure, the swath boundary may also be placed at an area having highest number of raster dots in the raster data. For example, the swath boundary may be placed at a horizontal line, such as a boundary line of a border or a table, in the raster data.
Thereafter, pass 4 is utilized to print text lines 19 to 24 in the same direction of pass 3, i.e., left to right direction. A swath boundary for the pass 4 is defined from text line 19 to text line 24. A white space is identified below text line 24 and the printing of text lines 19 to 24 requires utilizing only top n4 nozzles of the printhead. Further, the print media may be advanced to align top of the printhead to next area of printing, i.e, to text lines 25 to 28. Text lines 25 to 28 are printed under pass 5 in right to left direction.
However, the
After completion of the pass 1 and the pass 2, the print media is advanced to align the top of the printhead to a second portion (second set of raster lines) of the raster data covering an area b′ to c′. Similar to the printing of the first portion (a′ to b′), the second portion is printed in two passes: pass 3 and pass 4. The pass 3 performs 50% shingling in a left to right direction by utilizing top n1 nozzles from the plurality of nozzles of the printhead. The pass 4 performs 50% shingling in a right to left direction by utilizing top n2 nozzles from the plurality of nozzles of the printhead. The top n1 nozzles may be a first subset of the topmost nozzles of the plurality of nozzles, and the top n2 nozzles may include a second subset of nozzles, subsequent to the first subset of nozzles, of the plurality of nozzles.
In
The foregoing description of several methods and an embodiment of the disclosure have been presented for purposes of illustration. It is not intended to be exhaustive or to limit the disclosure to the precise steps and/or forms disclosed, and obviously many modifications and variations are possible in light of the above description. It is intended that the scope of the disclosure be defined by the claims appended hereto.
