Patent ID: 12214989

DETAILED DESCRIPTION

Certain industrial printers utilize printheads mounted on printbars to deposit inks or other print agents upon a sheet of media. In examples the media sheets may range from 50 cm×50 cm to from 180 cm×250 cm, with the media weighing up to 10 kilograms. Some industrial printers have incorporated moving pallets, train and wagons on tracks, and/or vertical drops to transport such medias through a printer for printing with a high level of success. However, such systems can be challenging to scale for use with industrial printers that would print at higher speeds. Other industrial sheet-fed printers incorporate media transport systems that rely upon flexible belts for transporting the media. However, such systems have typically included a multitude of closely arranged belts to achieve media motion accuracy, with the result that such systems can be expensive and complex.

To address these issues, various examples described in more detail below provide a new system for media conveyance using transport assemblies that enable accurate media sheet transfer at a lower cost and complexity. In examples of the disclosure, a media sheet conveyance system includes a first transport assembly, a set of subject transport assemblies, and a controller. The first transport assembly includes an endless first belt having a multiple rows of holes. The multiple rows include a first and a second edge row separated by a distance “x.”

The first transport assembly includes a first drive roller operatively connected to the first belt, and a first vacuum element set positioned adjacent and beneath a surface of the first belt. Each of the subject transport assemblies of the set of subject transport assemblies includes an endless subject belt having a subject edge row of holes, with a distance to a nearest edge row of an adjacent transport assembly being less than or equal to the distance “x.” A subject drive roller is operatively connected to the subject belt, and a subject vacuum element is positioned adjacent and beneath a surface of the subject belt.

The controller is to control the first drive roller and the subject drive rollers to move a media sheet, including controlling the first drive roller to circulate the first belt over the first vacuum element set and controlling a subject drive roller to circulate a subject belt over the subject vacuum element. The suctions created by the vacuum elements, applied through the holes of the first belt and the subject belts, are to cause the media sheet to be held tightly to the first belt and the subject belts.

In certain examples, the first transport assembly includes a first encoder unit to measure movement of the first belt, and each of the plurality of subject transport assemblies includes a subject encoder unit to measure movement of the subject belt. In such instances, the controller is operatively connected to the first encoder unit and to each of the subject encoder units, and is to control the first drive roller and the subject drive rollers based upon belt movements measured by the first encoder unit and the subject encoder units.

In particular examples, the system for media conveyance is included within a printer that is to apply a print agent to a media sheet in a print zone of the printer. In examples, the controller is to control the first drive roller and the subject drive rollers to making skew correction adjustments in the speed of a belt as the media sheet is conveyed by the first and subject belts through the print zone based upon belt movements measured by the first and subject encoder units. In certain examples, the controller is to control the first drive roller and the subject drive rollers to accurately correct for any unwanted variations in belt speeds as the media sheet is conveyed through the print zone. In particular examples the first and subject encoder units are positioned within the print zone to increase accuracy of the measurements of belt movements within the print zone.

Users and providers of printers and other devices will appreciate that the disclosed system enables precise movement of media sheets through a printers' print zone utilizing significantly less media conveyance hardware and reduced control complexity as compared to current systems. Media sheets of varying widths may be accurately transported through a printer's print zone with greater precision, while utilizing significantly less belts and belt surfaces, than with existing belt conveyor systems. Installations and utilization of printers that include the disclosed system should thereby be enhanced.

FIGS.1-15Ddepict examples of physical and logical components for implementing various examples. InFIGS.1-13D, and15A-15Da component is described as a controller114. In describing controller114focus is on the controller's designated function. However, the term controller, as used herein, refers generally to hardware and/or programming to perform a designated function. As is illustrated later with respect toFIG.14, the hardware of the controller, for example, may include one or both of a processor and a memory, while the programming may be code stored on that memory and executable by the processor to perform the designated function.

FIG.1is a block diagram depicting an example of a system100for media conveyance with multiple transport assemblies. In this example, the media conveyance system100includes a first transport assembly102, and a set of subject transport assemblies 2 (104a)-N (104n). The first transport assembly102has an endless first belt108having a plurality of rows of holes, the plurality including a first and a second edge row separated by a distance “x”, a first drive roller110operatively connected to a drive surface (see e.g.,308,FIGS.12A-12D) of the first belt, and a first vacuum element set112positioned adjacent and beneath the drive surface of the first belt108(see e.g.,308,FIGS.3A and3B). In examples the first vacuum element set112may include a plurality of individual vacuum elements each positioned adjacent and beneath one of the rows of the plurality of rows of holes of the first belt108. In other examples the first vacuum element set112may include a single vacuum element that has a set of channels, with each channel positioned adjacent and beneath one of the rows of the plurality of rows of holes of the first belt108.

As used herein a “belt” refers generally to a loop, e.g. a continuous loop, of material that is to link to rollers (such rollers are sometimes referred to as rotating shafts). In examples the belt may be made of, or include, natural rubber, vulcanized rubber, synthetic rubber, PVC or other materials. In examples the belt may be a belt of any of these materials, and also include metal reinforcing material. Such belts are sometimes referred to as timing belts.

As used herein a “drive surface” of a continuous belt is a side of the belt that is to engage a drive roller such that a drive roller can actuate the belt. As used herein a “drive roller” refers generally to a roller, pulley, or other substantially round element that is operatively connected to a driver surface of a continuous belt and operatively connected to a motor or other actuator, such that the drive roller is to rotate and thereby cause movement or circulation of the continuous belt. As used herein an “edge row” of holes of a belt refers generally to a row of holes that is extended along an edge of the continuous belt. As used herein an “edge” of a continuous belt is an imaginary line where a flat surface of a belt (e.g. a flat surface that is to support a media sheet) ends. As used herein a “vacuum element” refers generally to an apparatus or system that is to causes application of a suction or a negative pressure.

Each subject transport assembly 2-N of the set of subject transport assemblies includes an endless subject belt (e.g.,118aand118n) having a subject edge row of holes, with a distance to a nearest edge row of an adjacent transport assembly being less than or equal to the distance “x.” Each subject transport assembly 2-N of the set of subject transport assemblies includes a subject drive roller (120a-120n) operatively connected to a drive surface (see e.g.408FIGS.13A-13D) of the subject belts118a-118n, and a subject vacuum element122a-122npositioned adjacent and beneath a drive surface of the subject belt. The media conveyance system100includes a controller114to control the first drive roller110and the subject drive rollers120a-120nto move a media sheet. The controlling includes controlling the first drive roller110to circulate the first belt108over or above the first vacuum element set112, and controlling a subject drive roller120ato circulate a subject belt118aover the subject vacuum element122a, and controlling the subject drive roller120nto circulate a subject belt118nover the subject vacuum element122n.

FIG.2Ais a simple schematic diagram that illustrates an example of a media sheet conveyance system. In this example, the media conveyance system100includes a first transport assembly102, and a set of subject transport assemblies 2 (FIG.2104a)-5 (FIG.2104e).

The first transport assembly102has a first drive roller110operatively connected to a drive surface (see e.g.,308FIGS.12A-12D) of the first belt108, and has a first vacuum element set112positioned adjacent and beneath the drive surface of the first belt108. In this example, the plurality of rows of holes of the first belt108extend along length of the endless first belt108, and the first edge row202of holes and the second edge row204of holes of the first belt108are separated, in a direction orthogonal to the length of the belt, by the distance “x”206.

Moving toFIG.2B, in examples the distance “x” measured between the first edge row202and the second edge row204of the first belt108may be a distance measured from an imaginary centerline250that connects the centers of the holes of the first edge row202and an imaginary centerline260that connects the centers of the holes the second edge row204.

Returning toFIG.2A, each of the subject transport assemblies 1-5 of the set of subject transport assemblies104a-104eincludes an endless subject belt (118a,118b,118c,118d,118e) having a subject edge row of holes (212a,212b,212c,212d,212e), with a distance220to a nearest edge row of an adjacent transport assembly being less than or equal to the distance “x.” Each of the subject transport assemblies 1-5 of the set of subject transport assemblies104a-104eincludes a subject drive roller (120a,120b,120c,120d,120e) operatively connected to a drive surface of the subject belt (118a,118b,118c,118d,118e), and a subject vacuum element (122a,122b,122c,122d,122e) positioned adjacent and beneath the drive surface of the subject belt. It should be noted that whileFIG.2Aand other figures of this disclosure are described as having five subject transport assemblies104a-104e, in other examples the media conveyance system100may include any plurality of subject transport assemblies.

Returning toFIG.2B, in examples the distance220(that is less than the distance “x”260) between the edge row212aof the subject transport assembly 1104aand the nearest edge row202of the first transport assembly102is a distance measured between an imaginary centerline270that connects the centers of the holes of the edge row212aof the subject transport assembly 1104aand an imaginary centerline250that connects the holes of the first edge row202of the first transport assembly102. Similarly, the distances220(that are less than the distance “x”260) between an edge row (e.g. any of subject edge rows212a-212e) of a subject transport assembly (e.g. any of subject transport assemblies104a-104e) and a subject edge row of an adjacent transport assembly of transport assemblies104a-104eare distances measured between centerlines270of the subject edge rows. For instance the distance220(that is less than the distance “x”260) between the subject edge row212aof the subject transport assembly 1104aand an subject edge row212bof an adjacent transport assembly 2104bis a distance measured between the centerline270of the subject edge row212aof subject transport assembly 1104aand the centerline270of the subject edge row212bof the subject transport assembly 2104b.

It should be noted that while theFIGS.2A,2B,6-9,11, and15A-15Dare drawn such that the distance220between edge rows of various transport assemblies might be interpreted as being a same distance, this is not a requirement. For instance, looking atFIGS.2A and2B, the distance220between the first edge row202of the first transport assembly102and the subject edge row212aof the subject transport assembly 1104acould be, but is not required to be, a same distance as indicated between the subject edge row212aof the subject transport assembly 1104aand the subject edge row212bof the subject transport assembly 2104badjacent to subject transport assembly 1. In other words, each occurrence of “distance220” or reference number220as used herein represents any distance that is less than or equal to “distance “x”206, and should not be interpreted as necessarily a same distance.

FIGS.3A and3Bare simple schematic diagrams that illustrate in section views components of example first transport assemblies.FIG.3Aillustrates an example of a first vacuum element set112of a first transport assembly102. The first vacuum element set is positioned adjacent and beneath a drive surface308of the first belt108. In this example, the first vacuum element set112has a set of channels302connected to a same or common vacuum source304. Each channel of the set of channels302is positioned adjacent to and beneath one of the rows of holes210(FIGS.2A and2B) of the first belt108.

FIG.3Billustrates another example of a first vacuum element set112of a first transport assembly102. The first vacuum element set is positioned adjacent and beneath a drive surface308of the first belt108. The first vacuum element set112has a set of a set of separate or distinct vacuum sources304a-304h, with each of the separate or distinct vacuum sources304a-304hconnected to a dedicated channel of the channels302a-302h. Each channel of the set of channels302a-302his positioned adjacent to and beneath one of the rows of holes210(FIGS.2A and2B) of the first belt108.

FIG.3Cis an illustration in perspective view of an example of a particular channel302aand vacuum source304aof the vacuum element set112ofFIG.3B.

In each of the examples of each ofFIGS.3A,3B, and3C, the channels (302, and302a-302g) and the connected vacuum source(s) (304,304a-304g) are for exposing a media sheet (see e.g., media sheet1504FIGS.15A-15D) lying upon a surface of the first belt108(FIG.2A), opposite the drive surface308, to a negative pressure306FIG.3Capplied through the holes of the first belt108so as to cause the media sheet to be secured or held close to the first belt108.

FIGS.4A and4Bare simple schematic diagrams that illustrate in section and perspective views, respectively, example components of a subject transport assembly. In an example each subject transport assembly of subject transport assemblies104a-104e(FIGS.2A and2B) has a subject vacuum element122a-122e(FIGS.2A and2B) including a vacuum channel fluidly connected to a vacuum source.

Moving toFIG.4Ato look at the subject vacuum element 1122aas an example, the subject vacuum element 1122ais positioned adjacent and beneath a drive surface408of the subject belt118a. The subject vacuum element 1122ahas a channel402connected to a vacuum source404. The channel402and the vacuum source404are for applying a negative pressure406through a row of holes (212aFIG.2A) of the subject belt 1118ato cause a media sheet to be secured or held close to the subject belt 1118a. In examples, the other subject vacuum elements 1-4122a-122ehave a same or similar architecture.

Returning toFIG.2A, the media conveyance system100includes a controller114to control the first drive roller110and the subject drive rollers120a-120eto move the first belt108and the subject belts118a-118ein a media conveyance direction240. The controlling includes controlling the first drive roller110to circulate the first belt108over the first vacuum element set112, controlling the subject drive roller 1120ato circulate the subject belt 1118aover the vacuum element 1122a, controlling the subject drive roller 2120bto circulate the subject belt 2118bover the vacuum element 2122b, controlling the subject drive roller 3120cto circulate the subject belt 3118cover the vacuum element 3122c, controlling the subject drive roller 4120dto circulate the subject belt 4118dover the vacuum element 4122d, and controlling the subject drive roller 5120eto circulate the subject belt 5118eover the vacuum element 5122e.

In examples, the controller114is to control the first vacuum element set112to apply a target negative pressure to the media sheet that lies upon the first belt through the holes in the first belt108, and to control the subject vacuum elements 1-5122a-122eto apply a target negative pressure to that media sheet through the holes in the subject belts 1-5118a-118e. As used herein, a “target pressure” for a vacuum element refers generally to a predetermined pressure that the vacuum element is to create. In examples, the controller114may set a target pressure for a vacuum element, or a set of vacuum elements, according to received data indicative of a media attribute (e.g. thickness, weight, observed skew) or a printing attribute (e.g., a type of print job to be performed at a printer that incorporates the media conveyance system100).

FIG.5is a block diagram depicting an example of a media sheet conveyance system wherein the first transport assembly and subject transport assemblies include encoder units. In this example, the first transport assembly102includes a first encoder unit502to measure movement of an endless first belt108, and each of a plurality of subject transport assemblies104a-104nincludes a subject encoder unit504a-504nto measure movement of a subject belt118a-118n. The controller114is operatively connected to the first encoder unit502and to each of the subject encoder units504a-504n, and is to control the first drive roller110and the subject drive rollers120a-120nto convey a media sheet based upon belt movement measurements made by the first encoder unit502and the subject encoder units504a-504n.

FIG.6is a simple schematic diagram in plan view that illustrates example components of a media sheet conveyance system wherein the first transport assembly and the subject transport assemblies include encoder units. In this example, the first transport assembly102includes a first encoder unit502to measure movement of the first belt108, and each of the plurality of subject transport assemblies104a-104eincludes a subject encoder unit504a-504eto measure movement of a subject belt118a-118e.

In the particular example ofFIG.5, the first encoder unit502is operatively connected to the drive roller110of the first transport assembly102to measure movement of the first belt108. A subject encoder504ais operatively connected to the drive roller120aof the subject transport assembly104ato measure movement of the subject belt118a. A subject encoder504bis operatively connected to the drive roller120bof the subject transport assembly104bto measure movement of the subject belt118b. A subject encoder504cis operatively connected to the drive roller120cof the subject transport assembly104cto measure movement of the subject belt118c. A subject encoder504dis operatively connected to the drive roller120dof the subject transport assembly104dto measure movement of the subject belt118d. A subject encoder504eis operatively connected to the drive roller120eof the subject transport assembly104eto measure movement of the subject belt118e.

The controller114is operatively connected to the first encoder unit502and to each of the subject encoder units504a-504e, and is, in order to convey a media sheet in a media conveyance direction240, control the first drive roller110and the subject drive rollers120a-120ebased upon belt movement measurements made by the first encoder unit502and the subject encoder units504a-504e.

In examples, the first encoder502and/or a subject encoder unit of subject encoder units504a-504emay be operatively connected to a shaft of its respective drive roller110120a-120eto provide an indirect measurement of movement of the belt that is caused to be circulated by that drive roller. In other examples, the first encoder502and/or a subject encoder unit of subject encoder units504a-504emay have a measuring wheel that is operatively connected to a surface of its respective drive roller to provide an indirect measurement of the belt that is caused to be circulated by that drive roller.

The controller114is operatively connected to the first encoder unit502and to each of the subject encoder units504a-504e, and is to control the first drive roller110and the subject drive rollers120a-120ebased upon belt movement measurements made by the first encoder unit502and the subject encoder units504a-504e. In examples controlling the first drive roller and/or the subject drive rollers includes varying speed of the first drive roller and/or the subject drive rollers based upon belt movements measured by the first encoder unit and the subject encoder unit.

FIG.7is a simple schematic diagram that illustrates in plan view another example of a media sheet conveyance system. The media conveyance system ofFIG.7is substantially similar to the system as described with respect toFIG.2A, except that in the example ofFIG.7the particular subject transport assembly 1104aof the plurality of subject transport assemblies includes two subject edge rows (a first subject edge row212aand a second subject edge row212aa), rather than a single subject edge row as disclosed with respect toFIG.2A. In this example a subject edge row distance220abetween the first subject edge row212aand a nearest edge row of holes202of a first adjacent transport assembly (here the first transport assembly102) is less than or equal to the distance “x”206. In this example a subject edge row distance220bbetween the second subject edge row212aaof the particular subject transport assembly 1104aand a nearest edge row of holes212bof an adjacent transport assembly (here the subject transport assembly 2104b) is less than or equal to the distance “x”206.

It should be noted that the distances220aand220b, and the other illustrated distances220c220dand220ebetween subject transport assembly edge rows212band212c,212cand212d, and212dand212e, respectively, need not be a consistent or same distance. Each of the distances220a220b220c220dand220erepresents a distance that is less than or equal to the distance “x”206.

The subject transport assembly 1 ofFIG.7has two rows of holes that are both subject edge rows212a212aa. In examples, a subject transport assembly may have more than two rows of holes in total, including two subject edge rows. In examples, any one, or more than one, of the subject transport assemblies104a-104eof the media conveyance system100may have multiple rows of holes that include two subject edge rows.

FIG.8is a simple schematic diagram that illustrates in plan view another example of a media sheet conveyance system. The media conveyance system100ofFIG.8is substantially similar to the system as described with respect toFIGS.2A and2B, except that the plurality of rows of holes of the first transport assembly102are distributed across a set of belts, rather than included in a single belt108as described with respect toFIGS.2A and2B. In the example ofFIG.8, the first transport assembly110includes a set of endless belts108a-108jpositioned in parallel, the set having a plurality of rows of holes210a-210jincluding a first edge row210aand a second edge row210j. The first edge row210aof holes and the second edge row210jof holes are separated by a distance “x”206. The first transport assembly includes a drive roller110operatively connected to drive surfaces of the set of belts108a-108i, the drive roller110to circulate the set of belts108a-108jabove a vacuum element set112a-112jsituated adjacent and beneath drive surfaces of the set of belts108a-108i.

The media conveyance system includes a plurality of subject transport assemblies104a-104e. Each of the subject transport assemblies104a-104eincludes an endless subject belt118a-118ehaving a subject edge row212a-212eof holes, with a distance220between the subject edge row and a nearest edge row of an adjacent transport assembly that is less than or equal to the distance “x”206.

In the example ofFIG.8, each of the subject transport assemblies104a-104eincludes a subject drive roller120a-120eoperatively connected to a drive surface of the subject belt118a-118eto circulate the subject belt above a subject vacuum element122a-122e. The subject vacuum element of each of the subject transport assemblies104a-104eis to apply a negative pressure through holes of that subject transport assembly's subject belt.

The controller114, in order to convey a media sheet (see e.g., media sheet1504FIGS.15A-15D) in a media movement direction240, is to control the drive roller110to circulate the set of belts108a-108jover the vacuum element set112a-112j. The controller114, in order to convey a media sheet (see e.g.,1504FIGS.15A-D) in a media movement direction240, is to contemporaneously control the subject drive rollers120a-120eto circulate each of the subject belts118a-118eover its respective subject vacuum element of vacuum element set112a-112i. In examples the controller114is to control the vacuum element set112a-112fand the subject vacuum elements122a-122fto apply a target negative pressure to the media sheet through the rows of holes in the set of belts108a-108jand the subject belts118a-118e.

In examples, the media conveyance system100ofFIG.8may include a first encoder unit to measure movement of the set of belts, and, for each of the subject transport assemblies, a subject encoder unit to measure movement of the subject belt of that subject transport assembly. In these examples the controller114is to control the drive roller110and the subject drive rollers120a-120ebased upon belt movements measured by the first encoder unit and the subject encoder units.

FIG.9is a simple schematic diagram that illustrates in plan view another example of a media sheet conveyance system. The media conveyance system100ofFIG.9is substantially similar to the system as described with respect toFIG.8, except that the set of belts108a-108j, rather than being drive by a single drive roller, are each driven by a dedicated drive roller110a-110j. For instance, the drive roller110ais operatively connected to the belt108aof the set of belts, the drive roller110bis operatively connected to the belts108bof the set of belts, and so on. Each of the drive rollers110a-110jis to circulate a belt of the set of belts108a-108jof the first transport assembly102above a dedicated vacuum element of the vacuum elements112a-112j.

The controller114, in order to convey a media sheet in a media movement direction240, is to control the set of drive rollers110a-110jto circulate the set of belts108a-108jover the set of vacuum elements112a-112jof the first transport assembly102. In order to convey the media sheet in the media direction240, the controller114is to contemporaneously control the subject drive rollers120a-120eto circulate each of the subject belts118a-118eover its respective subject vacuum element of vacuum element122a-122e. In examples the controller114is to control the set of vacuum elements112a-112fand the subject vacuum elements122a-122fto apply a target negative pressure to the media sheet through the rows of holes in the set of belts108a-108jand the subject belts118a-118e. In this manner the controller114controls movement of the belts and the vacuum elements to cause precise transport of the media sheet.

FIG.10is a block diagram depicting an example of a printer with a media sheet conveyance system. In this example, a printer1000includes a print agent application element1020and a media conveyance system100. In examples the print agent application component may include a printhead or set of printheads. In examples the media conveyance system100may be as disclosed with respect to the examples ofFIGS.1-9discussed herein.

FIG.11is a simple schematic diagram that illustrates in plan view a particular example of a printer that has a media sheet conveyance system with multiple transport assemblies. In this example, the printer1000includes a plurality of print agent application elements1020a1020b1020c1020dto apply a print agent to a media sheet within a print zone1110. The printer1000includes a media sheet conveyance system100, the system including a first transport assembly102, a set of plurality of subject transport assemblies104a-104e, and a controller114.

As used herein a “print agent” refers generally to any substance (e.g. ink, dry toner, liquid toner, varnish, primer, etc.) that can be applied to a sheet media to form an image. As used herein a “print zone” refers generally to an area, situated beneath or otherwise adjacent to a print agent application element of a printer, within, in or under which the print agent application element is to apply a print agent to a media.

In examples the print agent application elements are printheads and are to eject a liquid print agent upon a media sheet as it is conveyed by the media conveyance system100through the print zone1110. As used herein, a “printhead” refers generally to a mechanism for ejection of a liquid, e.g., a liquid print agent. Examples of printheads are drop on demand printheads, such as piezoelectric printheads and thermo resistive printheads. As used herein, “liquid print agent” refers generally to any liquid that can be applied upon a media by a printer during a printing operation, e.g., a liquid print agent ejection operation, including but not limited to inks, primers and overcoat materials (such as a varnish), water, and solvents other than water. As used herein an “ink” refers generally to a liquid that is to be applied to a media during a printing operation, e.g., a liquid print agent ejection operation to form an image upon the media or to service a printhead. As used herein, a primer refers generally to a liquid substance that is applied to a media as a preparatory coating in advance of an application of ink or another image-forming print fluid to a media.

In this particular example the print agent application elements1020a1020b1020c1020dare printheads, each for applying a different color of liquid print agent to a media, and the print zone1110is an area situated adjacent and beneath the printhead print agent application elements.

In this example the first transport assembly102includes an endless first belt set108with a plurality of rows210of holes, the plurality including a first edge row202and a second edge row204separated by a distance “x”206. In this particular example the belt set108has a single belt. In other examples, the belt set108may include a plurality of belts (see, e.g.,FIGS.8and9). A first drive roller110is operatively connected to a drive surface (see e.g.,308,FIGS.12A-12D) of the first belt set108. A first vacuum element set112is positioned adjacent and beneath the drive surface (see e.g.,308,FIGS.3A and3B) of the first belt set108.

Continuing atFIG.11, the media conveyance system100of the printer1000includes a set of subject transport assemblies104a-104e. Each of the set of subject transport assemblies104a-104eincludes an endless subject belt118a-118ehaving a subject edge row212a-212eof holes, with a distance220to a nearest edge row of an adjacent transport assembly being less than or equal to the distance “x”206. In an example, the distances220between an edge row of the first transport assembly102and a subject edge row of the subject transport assembly 1104a, and as between subject edge rows of each of the subject transport assemblies 1-5104a-104e, are each less than or equal to the distance “x”206.

Each of the set of subject transport assemblies104a-104eincludes a subject drive roller120a-120eoperatively connected to a drive surface (see e.g.,408,FIGS.13A-13D) of the subject belt118a-118eof that subject transport assembly. Each of the set of subject transport assemblies104a-104eincludes a subject vacuum element122a-122epositioned adjacent and beneath a drive surface (see e.g.,408,FIGS.4A and4B) of the subject belt118a-118eof that subject transport assembly.

The media conveyance system100of the printer1000includes a controller114to control the first drive roller110and the subject drive rollers120a-120eto move a media sheet through the print zone1110. The controller114is to control the first drive roller110to circulate the first belt set108over the first vacuum element set112, and is to control the subject drive rollers120a-120eto independently circulate each of the subject belts118a-118eover a subject vacuum element122a-122epositioned adjacent to that subject belt.

Continuing with the example ofFIG.11, the first transport assembly102includes a first encoder unit1102situated within the print zone1110of the printer1000. The first encoder unit1102is to measure movement of the first belt set108. In this example each of the plurality of subject transport assemblies104a-104eincludes a subject encoder unit1104a-1104e, each situated within the print zone1110of the printer1000, to measure movement of a subject belt118a-118e.

In the particular example ofFIG.11, the first encoder unit1102is positioned within the print zone1110and is to measure movement of the first belt108. A subject encoder1104ais positioned within the print zone1110and is to measure movement of the subject belt118a. A subject encoder1104bis positioned within the print zone1110and is to measure movement of the subject belt118a. A subject encoder1104cis positioned within the print zone1110and is to measure movement of the subject belt118c. A subject encoder1104dis positioned within the print zone1110and is to measure movement of the subject belt118d. A subject encoder1104eis positioned within the print zone1110and is to measure movement of the subject belt118e.

FIGS.12A-12Dare simple schematic diagrams that illustrate, in view ofFIG.11, section diagrams of examples of a first encoder unit within a first transport assembly.FIG.12Aillustrates an example wherein the first encoder unit1102(FIG.11) is or includes an optical sensor1102apositioned within a print zone1110to detect and measure movement of the first belt108of the first transport assembly102.FIG.12Billustrates an example wherein a first encoder unit1102(FIG.11) positioned within a print zone1110is or includes a wheel encoder1102bthat is operatively connected to a drive surface308of the first belt108. In this manner the first encoder unit1102(FIG.11) is to provide a direct measurement of the movement of the first belt108.FIG.12Cillustrates an example wherein the first encoder unit1102(FIG.11) positioned within a print zone1110is or includes a wheel encoder1102coperatively connected to an intermediary roller1102d, wherein the intermediary roller1102dis in direct contact with a drive surface308of the first belt108. In this manner the first encoder unit1102(FIG.11) is to provide an indirect measurement of the movement of the first belt108.FIG.12Dillustrates an example wherein the first encoder unit1102(FIG.11) positioned within a print zone1110is or includes a wheel encoder1102eoperatively connected to an intermediary belt1102fthat is in direct contact with a drive surface308of the first belt108. The intermediary belt1102fis operatively connected to a first support roller1102gand a second belt support roller1102h. In this manner the first encoder unit1102(FIG.11) is to provide an indirect measurement of the movement of the first belt108.

The section views of the examples ofFIGS.12B and12Cdepict the drive roller110and a drive surface308of the belt108that is to engage the drive roller110as having teeth1250, The section views of the examples ofFIGS.12A and12Ddepict the drive roller110and a drive surface308of the belt108that is to engage the drive roller110without either the belt108or the drive roller110having teeth. It should be noted that any of the examples of first transport assemblies described herein may have a drive roller110with or without teeth, and a belt108with or without teeth to engage the drive roller110.

The vacuum element set112that is situated adjacent and beneath the drive surface308of the first belt108ofFIG.11, is not depicted inFIGS.12A-12D.FIGS.3A-3C, discussed previously, provide section view examples of a vacuum element set112.

FIGS.13A-13Dare simple schematic diagrams that illustrate, in view ofFIG.11, section diagrams of examples of a subject encoder unit within a subject transport assembly.FIG.13Aillustrates an example wherein the subject encoder unit1104a(FIG.11) positioned within a print zone1110is or includes an optical sensor1104aato detect and measure movement of the subject belt118aof the subject transport assembly104a.FIG.13Billustrates an example wherein a subject encoder unit1104a(FIG.11) positioned within a print zone1110is or includes a wheel encoder1104bbthat is operatively connected to a drive surface408of the subject belt118a. In this manner the subject encoder unit1104a(FIG.11) is to provide a direct measurement of the movement of the subject belt118a.FIG.13Cillustrates an example wherein the subject encoder unit1104a(FIG.11) positioned within a print zone1110is or includes a wheel encoder1104ccoperatively connected to an intermediary roller1104dd, wherein the intermediary roller1104ddis in direct contact with a drive surface408of the subject belt118a. In this manner the subject encoder unit1104a(FIG.11) is to provide an indirect measurement of the movement of the subject belt118a.FIG.13Dillustrates an example wherein the subject encoder unit1104a(FIG.11) positioned within a print zone1110is or includes a wheel encoder1104eeoperatively connected to an intermediary belt1104ffthat is in direct contact with a drive surface408of the subject belt118a. The intermediary belt1104ffis operatively connected to a first support roller1104ggand a second belt support roller1104hh. In this manner the subject encoder unit1104a(FIG.11) is to provide an indirect measurement of the movement of the subject belt118a.

The section views of the examples ofFIGS.13B and13Cdepict the subject drive roller120aand a drive surface408of the subject belt118athat is to engage the drive roller120as having teeth1350, The section views of the examples ofFIGS.13A and13Ddepict the subject drive roller120aand a drive surface408of the subject belt118athat is to engage the subject drive roller120awithout either the subject belt118aor the subject drive roller120ahaving teeth. It should be noted that any of the examples of subject transport assemblies described herein may have a subject drive roller120awith or without teeth, and a subject belt118awith or without teeth to engage the subject drive roller120a.

The vacuum element122athat is situated adjacent and beneath the drive surface408of the belt118aof the transport assembly 1104aofFIG.11is not depicted inFIGS.13A-13D.FIGS.4A and4B, discussed previously, provide section view examples of a vacuum element122a.

Returning toFIG.11, the controller114is operatively connected to the first encoder unit1102and to each of the subject encoder units1104a-1104e, and is to control the first drive roller110and at least one of the subject drive rollers120a-120ebased upon belt movement measurements made by the first encoder unit1102and the subject encoder units1104a-1104e.

In a particular example, the controller114is to control the first drive roller110and one or more of the subject drive rollers120a-120eby varying a speed of first drive roller110or varying a speed of the subject drive roller(s) based on a movement of the first belt and a movement of the subject belt(s) as measured by the first encoder unit1102and the subject encoder unit(s)1104a-1104e. For example, the controller114may control the first drive roller110and at least one of the subject drive rollers of the set (e.g., subject drive roller120aof the first subject transport assembly104a) by varying a speed of first drive roller110and varying speed of the subject drive roller120a) based on a movement of the first belt108as measured by the first encoder unit1102and a movement of the first subject belt118aas measured by the first subject encoder unit1104a. In examples, the controller114may cause the speeds of one or more of the other subject drive rollers of the set of subject drive rollers104a-104eto be independently increased or decreased based upon movements of the subject belts118b-118eas measured by the subject encoder units1104b-1104e.

In certain examples where the print application elements1020a1020b1020c1020dare printheads, the controller114is to synchronize printhead firing signals for the printheads1020a1020b1020c1020dbased on a movement of the first belt108and movement of the subject belts118a-118eas measured by the first encoder unit1102and the subject encoder units1104a-1104e. As used herein, a “printhead firing signal” refers generally to a variance in voltage, current, electromagnetic wave, or another medium that when provided to a printhead is to establish, or cause a change in, that printhead's timing and/or the volume of a liquid print agent ejected by the printhead during a printing operation or a non-printing operation.

In the foregoing discussion ofFIGS.1-13D, controller114was described as a combination of hardware and programming. Controller114may be implemented in a number of fashions. Looking atFIG.14the programming may be processor executable instructions stored on a tangible memory resource1450and the hardware may include a processing resource1460for executing those instructions. Thus, memory resource1450can be said to store program instructions that when executed by processing resource1460implement the controller114ofFIGS.1-13D.

Memory resource1450represents generally any number of memory components capable of storing instructions that can be executed by processing resource1460. Memory resource1450is non-transitory in the sense that it does not encompass a transitory signal but instead is made up of a memory component or memory components to store the relevant instructions. Memory resource1450may be implemented in a single device or distributed across devices. Likewise, processing resource1460represents any number of processors capable of executing instructions stored by memory resource1450. Processing resource1460may be integrated in a single device or distributed across devices. Further, memory resource1450may be fully or partially integrated in the same device as processing resource1460, or it may be separate but accessible to that device and processing resource1460.

In one example, the program instructions can be part of an installation package that when installed can be executed by processing resource1460to implement device100. In this case, memory resource1450may 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 resource1450can include integrated memory such as a hard drive, solid state drive, or the like.

Continuing atFIG.14, the executable program instructions stored in memory resource1450are depicted as a control module1414. Control module1414represents program instructions that when executed by processing resource1460may perform any of the functionalities described above in relation to controller114ofFIGS.1-13D.

FIGS.15A-15Dare simple schematic diagrams depicting examples of media sheet conveyance utilizing multiple transport assemblies. The examples ofFIGS.15A-15Ddemonstrate how the disclosed media conveyance system100can be used to transport media sheets of differing widths through a print zone1110of a printer. The example printer1000ofFIGS.15A-15Dincludes a media conveyance system100and is substantially similar to the printer1000and media conveyance system100discussed with respect toFIG.11.

In each of the examples ofFIGS.15A-15D, a first lateral edge1502of a rectangular media sheet1504is positioned upon the first belt108of the first transport assembly102such that the first lateral edge1502covers, or partially covers, holes of a row of the rows of holes210of the first transport assembly102.

A second lateral edge1506of the media sheet1504is positioned upon a subject belt (118ainFIG.15A,118binFIG.15B,118cinFIG.15C, and118einFIG.15D) of a subject transport assembly (104ainFIG.15A,104binFIG.15B,104cinFIG.15C, and104einFIG.15D) such that the second lateral edge1506covers, or partially covers, holes of the row of holes of that subject belt. As used herein, a “lateral edge” of a media sheet refers generally to an edge of a media sheet that is not a leading edge or a trailer edge of the media sheet as it is being conveyed in a media conveyance direction.

In this manner, the first lateral edge1502of the media sheet1504is exposed, through the holes of the first belt108of the first transport assembly102to a negative pressure applied by a vacuum element112of the of the first transport assembly102. The second lateral edge1506of the media sheet1504is contemporaneously exposed through the holes of the row of holes of applicable subject belt (118inFIG.15A,118binFIG.15B,118cinFIG.15C, and118einFIG.15D) to a negative pressure applied by a vacuum element positioned adjacent and beneath the row of holes. In this manner each of the first lateral edge1502is held tightly to the first belt108belt of the first transport apparatus102, and the second lateral edge1506is held tightly to a belt of a subject transport assembly (104ainFIG.15A,104binFIG.15B,104cinFIG.15C, and104einFIG.15D), thereby enabling accurate media conveyance through the print zone1110and enhanced print quality.

FIGS.1-15Daid in depicting the architecture, functionality, and operation of various examples.FIGS.1-15Ddepict various physical and logical components, and various components are defined at least in part as programs or programming. Each such component, portion thereof, or various combinations thereof may represent in whole or in part a module, segment, or portion of code that comprises executable instructions to implement any specified logical function(s). Each component or various combinations thereof may represent a circuit or a number of interconnected circuits to implement the specified logical function(s). Examples can be realized in a memory resource for use by or in connection with a processing resource. A “processing resource” is an instruction execution system such as a computer/processor-based system or an ASIC (Application Specific Integrated Circuit) or other system that can fetch or obtain instructions and data from computer-readable media and execute the instructions contained therein. A “memory resource” is a non-transitory storage media that can contain, store, or maintain programs and data for use by or in connection with the instruction execution system. The term “non-transitory” is used only to clarify that the term media, as used herein, does not encompass a signal. Thus, the memory resource can comprise a physical media such as, for example, electronic, magnetic, optical, electromagnetic, or semiconductor media. More specific examples of suitable computer-readable media include, but are not limited to, hard drives, solid state drives, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM), flash drives, and portable compact discs.

It is appreciated that the previous description of the disclosed examples is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to these examples will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other examples without departing from the spirit or scope of the disclosure. Thus, the present disclosure is not intended to be limited to the examples shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the blocks or stages of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features, blocks and/or stages are mutually exclusive. The terms “first”, “second”, “third” and so on in the claims merely distinguish different elements and, unless otherwise stated, are not to be specifically associated with a particular order or particular numbering of elements in the disclosure.