BACKGROUND [0001] Printing devices include standalone printers as well as multifunction devices (MFDs), multifunction printers (MFPs), and all-in-one (AlO) devices that include printing functionality as well as other functionality, such as scanning, copying, and/or faxing, and so on. A printing device uses colorant to form images on physical media such as paper. For example, a laser printing device uses toner, whereas an inkjet printing device uses ink.

[0002] A monochromatic printing device uses one color of colorant to print on physical media. For example, a black-and-white printing device uses black colorant. A color printing device uses a number of colorants corresponding to the color space or color model that the printing device employs to print full-color images on physical media. For example, a color printing device can use cyan, magenta, yellow, and black colorant, corresponding to a cyan, magenta, yellow, and black (CMYK) color space.

BRIEF DESCRIPTION OF THE DRAWINGS

[0003] FIG. 1 is a block diagram of an example printing device. [0004] FIG. 2 is a diagram of example operation of the printing device of

FIG. 1 to print monochromatic print jobs.

[0005] FIG. 3 is a diagram of example operation of the printing device of

FIG. 1 to print a color print job. [0006] FIG. 4 is a flowchart of an example method for printing a

monochromatic print job by the printing device of FIG. 1.

[0007] FIG. 5 is a flowchart of an example method for printing a color print job by the printing device of FIG. 1. DETAILED DESCRIPTION

[0008] As noted in the background, a color printing device uses a number of colorants corresponding to the color space or color model that the printing device employs to print full-color images on physical media. A color laser printer, for instance, may use cyan, magenta, yellow, and black toner so that the printer can print in full color. The different colorants can be differently combined on a pixel-by-pixel basis of an image to be printed on a physical medium to yield the colors of image's pixels.

[0009] A color printing device can still print monochromatic images. For example, a color printing device that has black colorant in addition to cyan, magenta, and yellow colorant can use the black colorant to print in just black and white (including in gray scale). As another example, a color printing device that lacks black colorant but that has cyan, magenta, and yellow colorant can print black-and-white images by printing in cyan, magenta, and yellow in equal amounts to achieve black-and-white (including gray scale) printing.

[0010] A color printing device may receive a print job in compressed form from a host device like a computing device such as a desktop or laptop computer. The printing device therefore has to perform processing on the print job prior to a print engine of the printing device outputting colorant on physical media to print the print job. Processing includes decompression of the compressed data of the received print job, and may also including other processing, such as halftoning, and so on.

[0011] The print engine is the mechanism of the printing device that outputs colorant onto physical media to print the print job. For example, a laser printing device uses a laser print engine to apply toner onto physical media like paper. By comparison, an inkjet printing device uses an inkjet print engine to apply ink onto such physical media. The printing device controls the print engine according to the received print job after the print job has been processed.

[0012] To aid in the processing of a print job, a printing device can include a circuit, such as an integrated circuit (IC) like an application-specific IC (ASIC). The circuit can process a print job more quickly than a general-purpose processor, such as a central processing unit (CPU), which may also be included in the printing device. An example of such a circuit is a time-delineated multipurpose (TDMP) ASIC.

[0013] Within a color printing device, such a circuit can include a number of channels corresponding to the different color colorants of the printing device. For example, if the printing device includes cyan, magenta, yellow, and black colorants, then there are four color channels. When the printing device receives a compressed print job, each color channel of the circuit is responsible for performing processing on the data for a different color component (e.g., cyan, magenta, yellow, or black) of the print job. The channels can process their respective color components in parallel with one another. [0014] When such a color printing device having a circuit with multiple color channels corresponding to the different color colorants of the printing device receives a monochromatic print job, just the color channel corresponding to the color of the print job processes the print job. For instance, just the black channel processes a black-and-white print job. The other color channels of the circuit, such as the cyan, magenta, and yellow channels, remain unused.

[0015] Techniques are disclosed herein leverage these unused color channels to perform faster processing of monochromatic print jobs within a color printing device. For instance, a monochromatic print job may have a number of pages. Rather than having the same color channel sequentially process the pages of the print job, all the color channels of the printing device's circuit may be employed to process multiple pages of the print job in parallel. For example, the cyan channel may process the first page, while the magenta channel processes the second page, the yellow channel processes the third page, and the black channel processes the fourth page.

[0016] Therefore, for a color printing device having a circuit with N color channels corresponding to N different color colorants, processing of

monochromatic print jobs can occur at up to N times more quickly than if just one channel were used to process these print jobs. Monochromatic print jobs by definition use just one color colorant, such as black colorant. Nevertheless, the techniques disclosed herein leverage the color channels of the circuit

corresponding to the other color colorants, such as cyan, magenta, and yellow, to also process such monochromatic print jobs, even though the other color channels do not correspond to the colorant color of the print jobs.

[0017] FIG. 1 shows an example color printing device 100. The printing device 100 may be a standalone printer, or a multifunction device (MFD), multifunction printer (MFP), or all-in-one (AIO) device that includes printing functionality as well as other functionality, such as scanning, copying, and/or faxing, and so on. The printing device 100 includes a processor 102, a non- transitory computer-readable data storage medium 104, a colorant supply 106, a circuit 108, and a print engine 1 10.

[0018] The processor 102 may be a CPU, such as one having a complex instruction set computer (CISC) architecture or a reduced instruction set computer (RISC) architecture. The non-transitory computer-readable data storage medium 104 may be a volatile or a non-volatile medium, may be a semiconductor or a magnetic medium, and so on. The storage medium 104 stores program code 1 16 that the processor 102 executes, such as to perform methods that are described later in the detailed description.

[0019] The colorant supply 106 is a supply of colorants of multiple colors, and which may be dry or liquid toner, solid or liquid ink, and so on. In the example of FIG. 1 , the colorant supply 106 includes cyan colorant 1 12C, magenta colorant 1 12M, yellow colorant 1 12Y, and black colorant 1 12K, which are collectively referred to as the colorants 1 12, and which correspond to the colors of he CMYK color space. The colorant supply 106 can include colorants of multiple colors that correspond to other color spaces instead, however. [0020] The circuit 108 may be an IC, such as an ASIC. The circuit 108 is a special-purpose circuit to perform processing on received print jobs, such as decompression, halftoning, and so on. The processor 102 can thus offload such processing onto the circuit 108, which can perform the processing more quickly than the processor 102 can by executing the code 1 16. The circuit 108 may be a TDMP ASIC.

[0021] The circuit 108 includes multiple data-processing color channels corresponding to the colorants 1 12 and thus to the colors of the color space that the printing device 100 employs to print in full color. In the example of FIG. 1 , therefore, the circuit includes a data-processing cyan channel 1 14C, a data- processing magenta channel 1 14M, a data-processing yellow channel 1 14Y, and a data-processing black channel 1 14K, which are collectively referred to as the data-processing color channels 1 14. The color channels 1 14C, 1 14M, 1 14Y, and 1 14K therefore respectively correspond to the colors of the colorants 1 12C, 1 12M, 1 12Y, and 1 12K.

[0022] Each data-processing color channel 1 14 can be a data pipeline, which is a set of connected data processing elements. The input of a color channel 1 14 can be a print job or a page of a print job, such as a compressed print job. The output of a color channel 1 14 is the processed form of the print job or the page in question, such as a decompressed print job. The processing of one color channel 1 14 is independent of the processing of each other color channel 1 14. As such, the processing of the color channels 1 14 can be performed in parallel. [0023] The print engine 1 10 forms images on physical media, such as paper, and thus is the mechanism of the printing device 100 that prints received print jobs. More specifically, the print engine 1 10 uses the colorants 1 12 from the colorant supply 1 16 to print on physical media, monochromatically or in (full) color. The print engine 1 10 may be a laser print engine, in which case the colorants 1 12 may be toner and the printing device 100 is a laser printing device. The print engine 1 10 may be an inkjet print engine, in which case the colorants 1 12 may be ink and the printing device 100 is an inkjet printing device.

[0024] In general, the processor 102 receives a print job, such as from a host device like a computing device such as a desktop or a laptop computer. In one implementation, the print job can have multiple pages. In another

implementation, a print job may be considered an "overall" print job having multiple pages that themselves each correspond to single-page print jobs. The received print job can be compressed. The processor 102 in general sends the received print job to circuit 102 for processing, such as decompression. The processor 102 then controls the print engine 1 10 according to the processed print job to print the print job onto a physical medium; it is synonymously stated in this respect that the processor 102 transmits the processed print job to the print engine 1 10 for printing the print job.

[0025] FIG. 2 illustratively depicts example operation of the printing device 100 of FIG. 1 in printing monochromatic print jobs. The processor 102, the data- processing color channels 1 14 of the circuit 108, and the print engine 1 10 are explicitly shown in FIG. 2. The computer-readable data storage medium 104 with its program code 1 16 and the colorant supply 106 with its differently colored colorants 1 12 are not shown in FIG. 2 for illustrative clarity and convenience. However the medium 104 and the colorant supply 106 are both present during the operation of FIG. 2. For instance, the functionality ascribed to the processor 102 can be realized by the processor 102 executing the code 1 16 from the medium 104, and the print engine 1 10 prints onto physical media using the colorants 1 12 of the colorant supply 106.

[0026] The processor receives monochromatic print jobs 202A, 202B, 202C, and 202D, which are collectively referred to as the print jobs 202. The print jobs 202 may be separate print jobs, in which case in the example of FIG. 2, the print job 202A is received before the print job 202B, which is received before the print job 202C, which is received before the print job 202D. The print jobs 202 can be separate pages of the same "overall" print job, in which case in the example of FIG. 2, the print jobs 202A, 202B, 202C, and 202C respectively correspond to the first, second, third, and fourth pages of this print job.

[0027] Each of the print jobs 202 is monochromatic in that the print engine 1 10 uses just one color 1 to print an image corresponding to the print job 202 onto a physical medium like paper. For example, each of the print jobs 202 may be a black-and-white print job, such that the print engine 1 10 uses just the black colorant 1 12K to print a corresponding image onto a physical medium. The print jobs 202 may be of the same or different color, however.

[0028] In the example of FIG. 2, the processor 102 transmits the print job 202A to the color channel 1 14C for processing, the print job 202B to the color channel 1 14M for processing, the print job 202C to the color channel 1 14Y for processing, and the print job 202D to the color channel 1 14K for processing. Therefore, the color channels 1 14 can process their respectively received print jobs 202 in parallel. For instance, if the print jobs 202 are compressed, the channels 1 14 may decompress the print jobs 202.

[0029] The processor 102 thus transmits each print job 202 to a given color channel 1 14 regardless of whether the color of colorant 1 12 to which the channel 1 14 corresponds is the color of the print job 202 in question. For instance, each print job 202 may be a black-and-white print job that uses black colorant 1 12K. Nevertheless, the print job 202A is transmitted to the cyan color channel 1 14C, the print job 202B is transmitted to the magenta color channel 1 14M, and the print job 202C is transmitted to the yellow color channel 1 14Y. Just the print job 202D happens to be transmitted to the black color channel 1 14K; that is, just the print job 202D happens to be transmitted to the color channel 1 14K corresponding to the color of the print job 202D.

[0030] The color channels 1 14C, 1 14M, 1 14Y, and 1 14K output processed versions of the print jobs 202A, 202B, 202C, and 202D, respectively, which are identified as the processed print jobs 202A', 202B', 202C, and 202D' in FIG. 2, and which are collectively referred to as the process print jobs 202'. The processed print jobs 202' are output to the print engine 1 10. Stated in another way, the processor 102 can, upon completion of processing of each print job 202 by a corresponding color channel 1 14, transmit the respective processed print job 202' to the print engine 1 10. The print engine 1 10 then uses the colorant supply 106 of FIG. 1 to output the processed print job 202' in question onto a physical medium.

[0031] The color channels 1 14 may not output the processed print jobs 202' in the order in which the processor 102 transmitted the print jobs 202 to the channels 1 14 for processing. For example, a first print job 202 may be more complex than a second print job 202, such that the color channel 1 14 processing the first print job 202 takes longer to output the corresponding processed print job 202' than the color channel 1 14 processing the second print job 202 does to output its corresponding processed print job 202'. As such, even if the processor 102 transm its the first print job 202 to one color channel 1 14 before the

processor 102 transmits the second print job 202 to a different color channel 1 14, the latter channel 1 14 may output a corresponding processed print job 202' before the former channel 1 14 outputs its corresponding processed print job 202'.

[0032] If the print jobs 202 are separate print jobs, the processor 102 may transmit the processed print jobs 202' to the print engine 1 10 in the order in which the color channels 1 14 output the processed print jobs 202'. Therefore, the print engine 1 10 may print a relatively simple print job 202 before it prints a more complex print job 202, because the print job 202' corresponding to the complex print job 202 is completed before the print job 202' corresponding to the simple print job 202 is completed. This technique ensures optimal usage of the print engine 1 10.

[0033] However, if the print jobs 202 are pages of the same "overall" print job, the processor 102 transmits the processed print jobs' 202 to the print engine 1 10 in the order in which processor 102 transmits the print jobs 202 to the color channels 1 14. For example, if the print job 202A is the first page of a document and the print job 202B is the second page of this document, the print engine 1 10 prints the processed print job 202A' before the engine 1 10 prints the processed print job 202B', regardless of the order in which the processed print jobs 202A' and 202B' are completed by their respective color channels 1 14. In this example, for instance, the print job 202A may be more complex than the print job 202B, such that the processed print job 202B' is completed before the print job 202A' is completed. However, the processor 102 does not transmit the processed job 202B' to the print engine 1 10 before it transmits the processed print job 202A' to retain the page order of the "overall" print job of which the print jobs 202 are a part. Therefore, if the processed print job 202B' is completed before the processed print job 202A', the processor 102 still waits for completion of the processed print job 202A' so that the processor 102 can send the processed print job 202A' to the print engine 1 10 before it sends the already completed

processed print job 202B' to the engine 1 10.

[0034] FIG. 3 illustratively depicts example operation of the printing device 100 of FIG. 1 in printing a color print job. The processor 102, the data- processing color channels 1 14 of the circuit 108, and the print engine 1 10 are explicitly shown in FIG. 3. The computer-readable data storage medium 104 with its program code 1 16 and the colorant supply 106 with its differently colored colorants 1 12 are not shown in FIG. 3 for illustrative clarity and convenience.

However the medium 104 and the colorant supply 106 are both present during the operation of FIG. 3. For instance, the functionality ascribed to the processor 102 can be realized by the processor 102 executing the code 1 16 from the medium 104, and the print engine 1 10 prints onto physical media using the colorants 1 12 of the colorant supply 106.

[0035] The processor receives a color print job 302. The print job 302 is a color print job in that to print the print job 302, the print engine 1 10 uses more than one color of colorant 1 12 of the colorant supply 106 of FIG. 1. That is, the print engine 1 10 uses multiple colorants 1 12 to print the print job 302. By comparison, the print jobs 202 of FIG. 2 are monochromatic print jobs in that to print each print job 202, the print engine 1 10 uses just one color of colorant 1 12 of the colorant supply 106. That is, the print engine 1 10 uses just one colorant 1 12 to print each print job 202, which may be the same or different colorant 1 12 as that used for any other print job 202.

[0036] The processor 1 10 divides the color print job 302 in FIG. 3 into color components 304C, 304M, 304Y, and 304K, which are collectively referred to as the color components 304. More generally, the processor 1 10 divides the color print job 302 into color components 304 corresponding to the colors of the color space or model that the printing device 100 uses to print in color. Stated another way, the processor 1 10 divides the color print job 302 into color components 304 corresponding to the colors of the colorants 1 12. As part of this division process, the processor 1 10 may first convert the received print job 302 from one color space or model to the color space or model that the printing device 100 uses. For instance, the processor 1 10 may convert the print job 302 from a red, green, and blue (RGB) color space to the CMYK color space of the printing device 100, before performing color separation on the print job 302 into the constituent cyan, magenta, yellow, and black color components 304 of the CMYK color space.

[0037] The processor 1 10 transmits the color components 304 to the respective color channels 1 14 for processing. The cyan color channel 1 14C thus processes the cyan color component 304C, the magenta color channel 1 14M processes the magenta color component 304M, the yellow color channel 1 14Y processes the yellow color component 304Y, and the black color channel 1 14K processes the black color component 304K. The color channels 1 14 can process their respectively received color components 304 of the print job 302 in parallel. For instance, if the print job 302 is compressed, the channels 1 14 may decompress the resulting compressed color components 304 into which the processor 102 separates or divides the print job 302.

[0038] The color channels 1 14C, 1 14M, 1 14Y, and 1 14K output processed versions of the color components 304C, 304M, 304Y, and 304K of the print job 302, respectively, which are identified as the processed color components 304C, 304M', 304Y', and 304K' in FIG. 3, and which are collectively referred to as the processed color components 304'. The processed color components 304' are output to the print engine 1 10. Stated another way, the processor 102 can, upon completion of processing of the color components 304 by the color channels 1 14, transmit the processed color components 304' to the print engine 1 10. The print engine 1 10 then uses the colorant supply 106 of FIG. 1 to effectively output the print job 302 onto a physical medium.

[0039] The print engine 1 10 may have to have all the processed color components 304' of a page of the print job 302 before it can print an image corresponding to this page onto a physical medium. In this case, the processor 102 may not transmit the processed color components 304' of any page of any color print job to the print engine 1 10 until all the components 304' have been completed. However, the print engine 1 10 may use the colorants 1 12

corresponding to the color components 304' in a particular order to print an image corresponding to a page of a color print job 302. In this case, the processor 102 may transmit the processed color components 304' of any page of any color print job in the particular order in question to the print engine 1 10, such that the processor 102 may not have to wait for all the processed

components 304' to be completed before transmitting the components 304' to the print engine 1 12.

[0040] FIG. 4 shows an example method 400 for printing a monochromatic print job within the printing device 100. The method 400 may be implemented as the program code 1 16 stored on the computer-readable medium 104 and executed by the processor 102. The method 400 is performed for each monochromatic print job that the printing device 100 receives. In general, the method 400 receives monochromatic print jobs, transmits the received print jobs to unused color channels 1 14 for processing, and then transmits the processed print jobs to the print engine 1 10 for printing. [0041] More specifically then, the method 400 includes receiving a monochromatic print job (402), such as from a host computing device. As noted above, a print job may be considered as having one or more pages, or may be considered as one page of an "overall" print job. If there are no unused data- processing color channels 1 14 of the circuit 108 available for processing the received print job (404), then the method 400 waits until a color channel 1 14 becomes unused (406). For example, if four monochromatic print jobs have already been received and are currently undergoing processing by respective color channels 1 14, then a fifth received monochromatic print job has to wait for one of the color channels 1 14 to finish processing its current print job before the color channel 1 14 can process the new, fifth print job.

[0042] If there is an unused data-processing color channel 1 14 (404), or after waiting for a color channel 1 14 that is currently being used to finish its processing and thus again become unused (406), the method 400 selects an unused color channel 1 14 for the monochromatic print job received in part 402 (408). If there is more than one color channel 1 14 that is currently unused, the method 400 may select a particular color channel 1 14 for the received print job in any manner. For instance, the method 400 may randomly select a color channel 1 14 from the currently unused channels 1 14, or may select the color channel 1 14 successively, in order, from the channels 1 14C, 1 14M, 1 14Y, and 1 14K that are currently unused. As noted above, an unused color channel 1 14 is selected for a received monochromatic print job regardless of whether the colorant 1 12 to which color channel 14 corresponds is the (one) specified color of the print job. [0043] The method 400 thus transmits the received monochromatic print job to the selected data-processing color channel 1 14 (410). Once the selected color channel 1 14 has finished processing the print job, the method 400 transmits the processed print job to the print engine 1 10 for printing onto a physical medium (412). The selected color channel 1 14 thus again becomes unused. The processed print job may be transmitted to the print engine 1 10 in a particular order relative to other print jobs, as noted above. For example, if each print job corresponds to a page of an "overall" print job, then the method 400 may transmit the processed print jobs to the print engine 1 10 in the order of their appearance within the "overall" print job (i.e., in page order), regardless of the order in which their processing is completed by the color channels 1 14.

[0044] The method 400 is repeated each time a monochromatic print job is received, such as for a second print job, a third print job, and so on. As such, in one implementation, when the data-processing color channels 1 14 are all currently unused, repeated performance of the method 400 can result in successive selection of the color channels 1 14 for successively received print jobs, until none of the channels 1 14 remain unused. The receipt of another (e.g., fifth) monochromatic print job at that time, when the color channels 1 14 are all currently in use, results in part 406 being performed, such that the method 400 waits until one of the channels 1 14 again becomes unused. For instance, if each print job corresponds to a different print of an overall print job, the method 400 can successively transmit the print jobs to unused color channels 1 14 as they become available, until no more unprocessed print jobs (i.e., unprocessed pages) remain.

[0045] FIG. 5 shows an example method 500 for printing a color print job within the printing device 100. A color print job may be considered any print job that uses two or more colorants 1 12 to print, whereas a monochromatic print job may be considered any print job that uses just one colorant 1 12 to print. The method 500 may be implemented as the program code 1 16 stored on the computer-readable medium 104 and executed by the processor 102. The method 500 is performed for each color print job that the printing device 100 receives. The printing device 100 thus performs the methods 400 and 500 depending on the types of print jobs received.

[0046] The method 500 includes receiving a color print job (502), such as from a host computing device. The method 500 divides the print job into color components corresponding to the different colors of the colorants 1 12 (504). The method 500 transmits each color component of the print job to the corresponding data-processing color channel 1 14 (506). For example, the cyan color component can be sent to the cyan color channel 1 14C, the magenta color component can be sent to the magenta color channel 1 14M, the yellow color component can be sent to the color channel 1 14Y, and the black color component can be sent to the black color channel 1 14K.

[0047] If one or more of the color channels 1 14 are currently being used for processing of another color print job or for processing of a monochromatic print job, the method 500 can proceed in one of two ways. First, the method 500 may wait until all the color channels 1 14 remain unused before sending the color components of the received color print job to the channels 1 14. Second, the method 500 may send the color components of the received color print job to the color channels 1 14 as the color channels 1 14 are or become unused.

[0048] Once the color channels 1 14 have finished processing their respective color components of the print job, the method 500 transmits the processed print job to the print engine 1 10 for printing onto a physical medium (508). That is, the method 500 transmits the processed color components of the received print job to the print engine 1 10 for printing. The print engine 1 10 uses the colorants 1 12 corresponding to the color components to print the print job in color onto the physical medium.

[0049] The techniques that have been described leverage the data- processing color channels 1 14 of a circuit 108 of a printing device 100 for faster processing of monochromatic print jobs. Particularly, rather than just using the color channel 1 14 corresponding to the color of the monochromatic print jobs, all the color channels 1 14 may be employed so that monochromatic print jobs can be processed in parallel. A color channel 1 14 thus may process a

monochromatic print job corresponding to a color other than that to which the channel 1 14 itself corresponds.