Printhead spacing

A method of printing includes directing print media to a print zone between a printhead and a platen for a print job; and adjusting a spacing between the printhead and the platen during the print job, including one of adjusting the spacing within a page of the print job and adjusting the spacing between pages of the print job.

BACKGROUND

An inkjet printing system may include a printhead which ejects drops of ink through a plurality of nozzles or orifices and toward print media, such as a sheet of paper, so as to print on the print media. Typically, the orifices are arranged such that properly sequenced ejection of ink from the orifices causes characters or other images to be printed upon the print media as the printhead and the print media are moved relative to each other. Improper spacing between the printhead and the print media (too close or too far) may contribute to media damage, print jams, and poor print quality.

DETAILED DESCRIPTION

FIG. 1illustrates one example of an inkjet printing system10. Inkjet printing system10includes a fluid ejection assembly, such as printhead assembly12, and a fluid supply assembly, such as ink supply assembly14. In the illustrated example, inkjet printing system10also includes a carriage assembly16, a print media transport assembly18, a service station assembly20, and an electronic controller22.

Printhead assembly12includes one or more printheads or fluid ejection devices which eject drops of ink or fluid through a plurality of orifices or nozzles13. In one example, the drops are directed toward a medium, such as print media19, so as to print onto print media19. Print media19includes any type of suitable sheet material, such as paper, card stock, transparencies, Mylar, fabric, and the like. Typically, nozzles13are arranged in one or more columns or arrays such that properly sequenced ejection of ink from nozzles13causes characters, symbols, and/or other graphics or images to be printed upon print media19as printhead assembly12and print media19are moved relative to each other.

Ink supply assembly14supplies ink to printhead assembly12and includes a reservoir15for storing ink. As such, in one example, ink flows from reservoir15to printhead assembly12. In one example, printhead assembly12and ink supply assembly14are housed together in an inkjet or fluid-jet print cartridge or pen. In another example, ink supply assembly14is separate from printhead assembly12and supplies ink to printhead assembly12through an interface connection, such as a supply tube.

Carriage assembly16positions printhead assembly12relative to print media transport assembly18and print media transport assembly18positions print media19relative to printhead assembly12. Thus, a print zone17is defined adjacent to nozzles13in an area between printhead assembly12and print media19. In one example, printhead assembly12is a scanning type printhead assembly such that carriage assembly16moves printhead assembly12relative to print media transport assembly18. In another example, printhead assembly12is a non-scanning type printhead assembly such that carriage assembly16fixes printhead assembly12at a prescribed position relative to print media transport assembly18.

Service station assembly20provides for spitting, wiping, capping, and/or priming of printhead assembly12in order to maintain a functionality of printhead assembly12and, more specifically, nozzles13. For example, service station assembly20may include a rubber blade or wiper which is periodically passed over printhead assembly12to wipe and clean nozzles13of excess ink. In addition, service station assembly20may include a cap which covers printhead assembly12to protect nozzles13from drying out during periods of non-use. In addition, service station assembly20may include a spittoon into which printhead assembly12ejects ink to insure that reservoir15maintains an appropriate level of pressure and fluidity, and insure that nozzles13do not clog or weep. Functions of service station assembly20may include relative motion between service station assembly20and printhead assembly12.

Electronic controller22communicates with printhead assembly12, carriage assembly16, print media transport assembly18, and service station assembly20. Thus, in one example, when printhead assembly12is mounted in carriage assembly16, electronic controller22and printhead assembly12communicate via carriage assembly16. Electronic controller22also communicates with ink supply assembly14such that, in one implementation, a new (or used) ink supply may be detected, and a level of ink in the ink supply may be detected.

Electronic controller22receives data23from a host system, such as a computer, and may include memory for temporarily storing data23. Data23may be sent to inkjet printing system10along an electronic, infrared, optical or other information transfer path. Data23represents, for example, a document and/or file to be printed. As such, data23forms a print job for inkjet printing system10and includes one or more print job commands and/or command parameters.

In one example, electronic controller22provides control of printhead assembly12including timing control for ejection of ink drops from nozzles13. As such, electronic controller22defines a pattern of ejected ink drops which form characters, symbols, and/or other graphics or images on print media19. 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 controller22is located on printhead assembly12. In another example, logic and drive circuitry forming a portion of electronic controller22is located off printhead assembly12.

In one example, inkjet printing system10includes a media sensor24to sense parameters or characteristics of print media19, such as a type of print media19and/or a weight of print media19, and includes an environmental sensor26to sense ambient conditions of inkjet printing system10, such as a temperature and/or a humidity of inkjet printing system10, including where and/or when inkjet printing system10is operating. In one implementation, media sensor24and/or environmental sensor26provide input to determine and/or control a spacing between a printhead and a platen of inkjet printing system10, as described below.

In one example, as illustrated inFIG. 2, printhead assembly12is a wide-array or multi-head printhead assembly and includes a carrier1601, as an example of carriage assembly16, and a plurality of printhead dies1201mounted on carrier1601. In one implementation, printhead dies1201are arranged and aligned in one or more overlapping rows (as oriented inFIG. 2) such that printhead dies1201in one row overlap at least one printhead die1201in another row. As such, printhead assembly12may span a nominal page width or a width shorter or longer than a nominal page width. For example, printhead assembly12may span 8.5 inches of a Letter size print medium or a distance greater than or less than 8.5 inches of the Letter size print medium. While four printhead dies1201are illustrated as being mounted on carrier1601, the number of printhead dies1201mounted on carrier1601may vary.

In one implementation, printhead assembly12, as a wide-array or multi-head printhead assembly including printhead dies1201, is a non-scanning type printhead assembly such that carrier1601fixes printhead assembly12at a prescribed position relative to print media transport assembly18(FIG. 1). With a position of printhead assembly12fixed, print media19(FIG. 1) is moved or advanced relative to printhead assembly12during printing.

FIG. 3is a schematic illustration of one example of adjusting printhead spacing in an inkjet printing system, such as inkjet printing system10(FIG. 1). More specifically,FIG. 3is a schematic illustration of one example of adjusting a spacing between a printhead40, as an example of printhead assembly12(FIG. 1), and a platen30supporting print media19. More specifically, platen30is positioned opposite printhead40and supports print media19as print media is advanced through print zone17as defined between printhead40and platen30. As such, a printhead-to-platen spacing (PPS)50is defined between printhead40and platen30. Such spacing, also referred to as printhead-to-paper spacing and/or pen-to-paper spacing, is adjusted, as described below.

In one example, as schematically illustrated inFIG. 3, spacing50is adjusted by raising and lowering printhead40relative to platen30. More specifically, in one example, printhead40is raised and lowered orthogonal (i.e., substantially perpendicular) to platen30, as indicated by double arrow52. In one implementation, printhead40is supported by or slidingly coupled with a linear guide62, and raised and lowered along guide62by a motor64and a transmission arrangement66to adjust spacing50between printhead40and platen30. In the illustrated example, transmission arrangement66includes a rack-and-pinion arrangement. In another example, transmission arrangement66may include a worm gear arrangement. Other arrangements, configurations, systems or assemblies for effectuating linear movement or translation of printhead40may also be used. In one example, an adjusted spacing of printhead40is held by motor64(and transmission arrangement66), as described below.

In one implementation, an encoding system70is included to provide control of spacing50. In the illustrated example ofFIG. 3, encoding system70includes a rotary encoder72and an associated reader74. In another example, encoding system70may include a linear encoder and an associated reader. In one example, encoding system70including, more specifically, reader74, is communicated with electronic controller22(FIG. 1) to provide positional information of encoder72and, therefore, information (or input) as to a position of printhead40. As such, the position of printhead40may be correlated with spacing50of printhead40, as described below. In addition, in one example, motor64is communicated with electronic controller22(FIG. 1) such that, based on information (or input) from media sensor24, environmental sensor26, and/or other information of inkjet printing system10, spacing50of printhead40may be adjusted, as described below.

In one example, information of inkjet printing system10forming a basis for adjustment of spacing50of printhead40may include information or selections input or set by a user (for example, through a printer control panel or through a printer driver), and may be included in data23received by electronic controller22(FIG. 1). For example, a user may set a media type and/or select a media orientation, as described below, through a printer control panel or a printer driver.

In one implementation, spacing50of printhead40is adjusted “on-the-fly” and may be adjusted at anytime, as described below. In addition, spacing50of printhead40may be adjusted with incremental advancements and adjusted to indiscrete (or infinite) settings.

FIGS. 4A,4B, and4C illustrate different examples of printhead spacing, such as different examples of spacing50of printhead40. More specifically,FIG. 4Aillustrates one example of a “Low” spacing of printhead40,FIG. 4Billustrates one example of a “Medium” spacing of printhead40, andFIG. 4Cillustrates one example of a “High” spacing of printhead40. It is understood that the illustrated spacings of printhead40have been exaggerated for illustrative purposes.

In one example, the “Low” spacing of printhead40, the “Medium” spacing of printhead40, and the “High” spacing of printhead40are implemented in a printing system, such as inkjet printing system10, during a print job (for example, during processing, execution, or performance of a print job), as described below. In addition, the “Low” spacing of printhead40, the “Medium” spacing of printhead40, and the “High” spacing of printhead40are implemented in a printing system, such as inkjet printing system10, based on a condition (or conditions) of printing and/or a characteristic (or characteristics) of print media, such as print media19, as described below.

FIG. 5is a schematic illustration of one example of a selection500of printhead spacing, such as a selection of spacing50of printhead40. More specifically, in one example, spacing50of printhead40is selected based on a condition (or conditions) of printing, including before or during printing, and/or a characteristic (or characteristics) of print media, such as print media19. A condition of printing includes, for example, an environment502of the printing, a print mode504of the printing, and/or a media orientation506of the printing. In addition, a characteristic of print media19includes, for example, a media type508and/or a media weight510.

Environment502of the printing includes, for example, temperature and/or humidity, as measured, for example, by environmental sensor26. In one example, environment502considers whether an ambient temperature is “hot” or “cold”, and considers whether an ambient humidity is “low” or “high”. As such, spacing50of printhead40may be selected (and set) based on environmental conditions, as described below.

Print mode504of the printing includes, for example, a “Simplex” print mode (single-sided printing) or a “Duplex” print mode (two-sided printing) as defined or selected for the printing. In one example, printing with a “Simplex” print mode and printing with a “Duplex” print mode may include different spacings50of printhead40, as described below. More specifically, printing on different sides of a single sheet of print media19during a “Duplex” print mode may include different spacings50of printhead40for each side of the single sheet of print media19, as described below.

Media orientation506of the printing includes, for example, a “Portrait” orientation of print media19or a “Landscape” orientation of print media19as specified or selected for the printing. In one example, printing with a “Portrait” orientation and printing with a “Landscape” orientation may include different spacings50of printhead40, as described below. In one implementation, a “Portrait” orientation of print media19includes advancing print media19through inkjet printing system10, including through print zone17, in a direction parallel with a longer dimension of print media19and substantially parallel with a grain of print media19(“long grain”), and a “Landscape” orientation of print media19includes advancing print media19through inkjet printing system10, including through print zone17, in a direction perpendicular to a longer dimension of print media19and substantially perpendicular to a grain of print media19(“short grain”).

Media type508includes, for example, a type of print media19. For example, different types of print media19may include different spacings50of printhead40, as described below. In one example, the different types of print media19may include “Plain” paper, “Brochure”, “Photo” paper, “Envelope”, and “Card”. The type of print media19, however, may also include other types of print media.

Media weight510includes, for example, a weight of print media19. For example, different weights of print media19may include different spacings50of printhead40, as described below. In one example, the different weights of print media19may include “Light”, “Intermediate”, “Mid-Weight”, “Heavy”, and “Extra Heavy”.

FIG. 6is a flow diagram illustrating one example of a method600of printing. With method600, at602, print media, such as print media19, is directed to a print zone between a printhead and a platen for a print job, such as print zone17between printhead40and platen30, as schematically illustrated, for example, inFIG. 3.

At604, a spacing between the printhead and the platen is adjusted during the printing, such as spacing50between printhead40and platen30, as schematically illustrated, for example, inFIGS. 4A,4B, and4C. In one implementation, the spacing between the printhead and the platen is adjusted within a page of the print job. More specifically, one spacing of the printhead may be established for an end portion of the print media, and another spacing of the printhead may be established for an intermediate portion of the print media.

For example, a “High” spacing of the printhead may be established for a leading end of the print media (for example, as the print media is fed or advanced into the print zone), and a “Low” spacing of the printhead may be established for an intermediate portion of the print media (for example, once the leading end of the print media is through the print zone). In addition, a “High” spacing of the printhead may be established for a trailing end of the print media (for example, as the print media is exiting the print zone). As such, page curl or “cockle” of the leading end and/or the trailing end of the print media, which may result in jam problems, may be accounted for or compensated for by increasing the spacing (i.e., raising the printhead) for the leading end and/or the trailing end of the print media. In addition, acceptable or suitable print quality may be obtained by decreasing the spacing (i.e., lowering the printhead) for the intermediate portion of the print media (for example, as printing occurs in the intermediate portion of the print media).

In another implementation, the spacing between the printhead and the platen is adjusted between pages of the print job. More specifically, the spacing of the printhead may be adjusted between subsequent pages or consecutive pages of a single print job. For example, a first spacing of the printhead may be established for a first page of a print job and a second spacing of the printhead may be established for a second page of the same print job.

In one example, the first and second pages of a print job include different types of print media. For example, a “mixed media” print job may include different types of print media for different pages of the same print job (for example, “Envelope” for page 1 and “Plain Paper” for page 2). As such, different spacings of the printhead may be established for the different pages of the same print job (for example, “High” spacing for the “Envelope” as page 1 and “Low” spacing for the “Plain Paper” as page 2).

In another example, the first and second pages of a print job include opposite sides of one sheet of print media (i.e., a single sheet of print media). For example, a duplex print job includes printing on both sides of one sheet of print media (double-sided printing). As such, a first spacing of the printhead may be established for a first side of the one sheet of print media (as a first page of the print job), and a second spacing of the printhead may be established for a second side of the one sheet of print media (as a second page of the print job). For example, a “Low” spacing of the printhead may be established for the first side of the one sheet of print media, and a “Medium” spacing of the printhead may be established for the second side of the one sheet of print media. As such, page curl or “cockle” of the sheet, which may occur after printing on the first side of the sheet and may result in smearing and/or jam problems, may be accounted for or compensated for when the sheet is fed or advanced back to the print zone for printing on the second side of the sheet.

FIGS. 7A and 7Bare flow diagrams illustrating one example of a method700of printing. With method700, at702, print media, such as print media19, is directed to a print zone between a printhead and a platen for printing, such as print zone17between printhead40and platen30, as schematically illustrated, for example, inFIG. 3.

At704, a spacing between the printhead and the platen is adjusted, such as spacing50between printhead40and platen30, as schematically illustrated, for example, inFIGS. 4A,4B, and4C. In one implementation, the spacing between the printhead and the platen is adjusted based on a condition of the printing. A condition of the printing may include, for example, an environment of the printing, such as environment502, a print mode of the printing, such as print mode504, and/or a media orientation of the printing, such as media orientation506, as schematically illustrated, for example, inFIG. 5. As such, different spacings of the printhead may be established for different conditions of the printing, such as different selected or designated options for the printing, as described below.

At706, a spacing between the printhead and the platen is adjusted, such as spacing50between printhead40and platen30, as schematically illustrated, for example, inFIGS. 4A,4B, and4C. In one implementation, the spacing between the printhead and the platen is adjusted based on a characteristic of the print media. A characteristic of the print media may include, for example, a type of print media, such as media type508, and/or a weight of print media, such as media weight510, as schematically illustrated, for example, inFIG. 5. As such, different spacings of the printhead may be established for different media types and/or different media weights, as described below.

Although method600and method700are illustrated and described as separate methods of printing, it is understood that method600(partially or fully) and method700(partially or fully) may be included or combined (partially or fully) in a method of printing. In addition, an order or sequence of method600and/or method700may be varied.

FIG. 8is a flow diagram illustrating one example of an implementation800of a method of printing. More specifically, implementation800illustrates one example of implementing method600and/or method700.

With implementation800, at802, a print job is initiated. At804, the print job is received by a printing system, such as inkjet printing system10, and at806, sheet n of the print job is loaded in the printing system. At808, a PPS is selected for sheet n. More specifically, a printhead spacing, such as spacing50of printhead40, is selected for sheet n. The PPS may be selected, as further described herein. At810, sheet n is printed with the selected PPS.

At812, a determination is made as to whether sheet n is a duplex sheet. More specifically, a determination is made as to whether sheet n is to receive double-sided printing. If sheet n is to receive double-sided printing, at814, sheet n is determined to be a duplex sheet. As such, at808, a PPS is selected for the duplex side of sheet n, and at810, the duplex side of sheet n is printed with the selected PPS. More specifically, a printhead spacing, such as spacing50of printhead40, is selected for printing the second side (for example, back-side) of sheet n, and the second side of sheet n is printed with the selected spacing. For example, the PPS of the duplex side of sheet n (for example, second side) may be greater than the PPS of the simplex side of sheet n (for example, first side) to account for or compensate for possible curl or “cockle” of sheet n after the simplex side of sheet n has been printed. Printing of a duplex print job, however, may also include printing of both sides of the sheet (for example, first side and second side of sheet n) with the greater PPS to provide similar print quality on both sides of the sheet since printing with different printhead spacings for different sides of the sheet may result in different print qualities on the different sides.

Returning to812, if sheet n is not a duplex sheet (or sheet n has already been printed as a duplex sheet and is not to receive additional printing), at816, sheet n is ejected.

At818, sheet n+1 of the print job is loaded in the printing system. More specifically, the next sheet (if any) of the print job is loaded in the printing system. As such, at820,822,824,826, and828, the above-described sequence of selecting a PPS and printing with the selected PPS, determining a duplex printing, selecting a PPS and printing with the selected PPS if duplex printing is determined, and ejecting the printed sheet, is repeated. In one example, such sequence is repeated for each sheet of the print job. Thus, with implementation800, printhead spacing is adjusted between pages of the print job (for example, side one, side two of a duplex sheet) (for example, sheet n, sheet n+1).

FIG. 9is a flow diagram illustrating one example of an implementation900of a method of printing. More specifically, implementation900illustrates one example of implementing method600and/or method700.

With implementation900, at902, a print job is initiated. At904, the print job is received by a printing system, such as inkjet printing system10, and at906, sheet n of the print job is loaded in the printing system.

At908, a leading end (or portion) of sheet n is detected. In one example, the leading end (or portion) of sheet n is detected before sheet n enters the print zone. The leading end (or portion) of sheet n may be detected, for example, by media sensor24(FIG. 1).

At910, a PPS is selected for the leading end (or portion) of sheet n. More specifically, a printhead spacing, such as spacing50of printhead40, is selected for the leading end (or portion) of sheet n. The PPS may be selected, as further described herein.

At912, sheet n is detected. More specifically, an intermediate portion of sheet n (i.e., non-leading end portion, non-trailing end portion) is detected, and at914, a PPS is selected for sheet n. More specifically, a printhead spacing, such as spacing50of printhead40, is selected for the intermediate portion of sheet n. The PPS may be selected, as further described herein.

At916, sheet n is printed with the selected PPS. More specifically, sheet n is printed with the PPS selected for the intermediate portion of sheet n.

At918, a trailing end (or portion) of sheet n is detected. In one example, the trailing end (or portion) of sheet n is detected before sheet n exits the print zone. The trailing end (or portion) of sheet n may be detected, for example, by media sensor24(FIG. 1).

At920, a PPS is selected for the trailing end (or portion) of sheet n. More specifically, a printhead spacing, such as spacing50of printhead40, is selected for the trailing end (or portion) of sheet n. The PPS may be selected, as further described herein.

At922, sheet n is ejected. More specifically, sheet n is ejected with the PPS selected for the trailing end (or portion) of sheet n. Thus, with implementation900, printhead spacing is adjusted within a page of the print job (for example, leading end, intermediate portion, trailing end).

FIG. 10is a flow diagram illustrating one example of an implementation1000of a method of printing. More specifically, implementation1000illustrates one example of implementing method600and/or method700.

With implementation1000, at1002, a PPS selection is initiated. More specifically, selection of a printhead spacing, such as spacing50of printhead40, is initiated. At1004, a determination is made as to whether the print media to be printed on is “Plain Paper or Brochure”. If the print media to be printed on is “Plain Paper or Brochure”, at1006, a determination is made as to whether an orientation of the print media is “Portrait”. If the orientation of the print media is “Portrait”, at1008, a determination is made as to whether a “Simplex” sheet is to be printed (for example, single-sided printing or side one of two-sided printing). If a “Simplex” sheet is to be printed, at1010, a “Low” PPS is set.

Returning to1008, if a “Simplex” sheet is not to be printed (for example, a “Duplex” sheet (i.e., side two of two-sided printing) is to be printed), at1022, a determination is made as to whether the print media to be printed on is “Light Weight”. If the print media to be printed on is “Light Weight”, at1012, a “Medium” PPS is set.

Returning to1022, if the print media to be printed on is not “Light Weight”, at1010, a “Low” PPS is set.

Returning to1006, if an orientation of the print media is not “Portrait” (for example, an orientation of the print media is “Landscape”), at1012, a “Medium” PPS is set.

Returning to1004, if the print media to be printed on is not “Plain Paper or Brochure”, at1016, a determination is made as to whether the print media to be printed on is “Photo” paper. If the print media to be printed on is “Photo” paper, at1018, a determination is made as to whether an environment of the printing is a “Cold Environment” (for example, low temperature, low humidity). If the environment of the printing is a “Cold Environment”, at1012, a “Medium” PPS is set. In one example, with a “Cold Environment” of the printing, the “Medium” PPS is selected to provide greater spacing between the printhead and the print media so as to avoid possible contact with a printed image since the cold environment may lead to longer drying time of the printed image.

Returning to1018, if the environment of the printing is not a “Cold Environment”, at1010, a “Low” PPS is set.

Returning to1016, if the print media to be printed on is not “Photo” paper, at1020, a determination is made as to whether the print media to be printed on is an “Envelope”. If the print media to be printed on is an “Envelope” (or another type of thick print media), at1014, a “High” PPS is set. Thus, with implementation1000, printhead spacing is adjusted based on a condition of the printing (for example, “Portrait”, “Simplex”, “Cold Environment”), and adjusted based on a characteristic of the print media (for example, “Plain Paper or Brochure”, “Photo”, “Envelope”, “Light Weight”).

Although implementation800, implementation900, and implementation1000are illustrated and described as separate implementations of a method of printing, it is understood that implementation800(partially or fully), implementation900(partially or fully), and/or implementation1000(partially or fully) may be included or combined (partially or fully) in an implementation of a method of printing. In addition, an order or sequence of implementation800, implementation900, and/or implementation1000may be varied.

FIG. 11is a flow diagram illustrating one example of a sequence1100of setting printhead spacing, such as a sequence of setting spacing50of printhead40.

With sequence1100, at1102, setting of a PPS height is initiated. More specifically, setting of a printhead spacing, such as setting of spacing50of printhead40, is initiated. At1104, a “Home” position of the printhead is established. In one example, the “Home” position includes a “Low” PPS of the printhead. As such, at1104, the printhead is maintained in the “Low” position or returned to the “Low” position to home the printhead (for example, establish an initial, know position of the printhead).

At1106, a determination is made as to whether a PPS setting of “Low” is the correct setting. More specifically, a determination is made as to whether the PPS selected for the printhead is “Low” PPS. If the selected PPS is “Low”, at1108, an “OK to Print” is acknowledged since the printhead is already in the “Low” position. More specifically, the current PPS spacing of the printhead is the same as the selected PPS spacing for the printhead.

Returning to1106, if a PPS setting of “Low” is not the correct setting (for example, a PPS setting of “Medium” or “High” has been selected for the printhead), at1110, the printhead is lifted to the selected PPS. For example, at1106, a PPS setting of “Medium” or “High” is established for the printhead.

At1112, the position of the printhead is held or maintained, and, at1108, an “OK to Print” is acknowledged since the printhead has been moved to and is held at the selected PPS.