Patent Application
20150145914
The invention relates to the field of printing systems, and in particular, to aligning webs of media for continuous-forms printing systems.
Entities with substantial printing demands typically use a production printer. A production printer is a high-speed printer used for volume printing (e.g., one hundred pages per minute or more). Production printers include continuous-forms printers that print on a web of print media stored on a large roll.
A production printer typically includes a localized print controller that controls the overall operation of the printing system, and a print engine (sometimes referred to as an “imaging engine” or a “marking engine”). The print engine includes one or more printhead assemblies, with each assembly including a printhead controller and a printhead (or array of printheads). An individual printhead includes multiple (e.g., hundreds of) tiny nozzles that are operable to discharge ink as controlled by the printhead controller. A printhead array is formed from multiple printheads that are spaced in series across the width of the web of print media.
While the printer prints, the web is quickly passed underneath the nozzles, which discharge ink onto the web at intervals to form pixels. In order to ensure that the web is consistently positioned underneath the nozzles, steering systems can be used to align the web laterally with respect to its direction of travel. However, steering systems often use even-profile rollers that have little positional control of the lateral movements of web traveling through a continuous-forms printing system.
Embodiments described herein align an edge of a web of print media in an edge-justified printer system using a crowned roller. As the web travels through the printer system, the point of largest diameter along the crowned roller tends to position the center of the web at that point. Therefore, a change in position of the crowned roller imparts a corresponding change in position of a traveling web. For an edge-justified printer, the controlled adjustment of a crowned roller allows webs of different width sizes to be aligned at a common edge within the printing system.
One embodiment is a system that includes an edge justified printer, a crowned roller, and an adjustment mechanism. The edge justified printer is configured to print to a continuous-forms web of print media that uses a margin as a target alignment point for an edge of the web. The crowned roller includes an apex that is a point where the diameter of the crowned roller is largest. The adjustment mechanism is configured to adjust a lateral position of the apex to align the edge of the web with the margin.
Another embodiment is a method for edge-justified printing using a crowned roller. The method includes identifying a margin of an edge justified printer. The margin is a target alignment point for an edge of a web of print media in the edge-justified printer. The method also includes detecting that the edge of the web is not aligned with the margin. The method further includes adjusting a lateral position of an apex of a crowned roller to align the edge of the web with the margin, the apex being a point where a diameter of the crowned roller is largest.
Another embodiment is a continuous-forms printing system. The printing system includes a printer configured to print to webs of various width sizes and a frame configured to support one or more rollers that transport the webs through the printer. The printing system also includes a crowned roller configured to tension the webs with an apex that is a point where a diameter of the crowned roller is largest. The printing system further includes a controller. The controller is configured to receive information regarding a web width change, and to adjust the position of the crowned roller in the frame. The adjustment is made in accordance with the web width change to align a common edge of each of the webs to a common location in the frame despite the web width change.
Other exemplary embodiments (e.g., methods and computer-readable media relating to the foregoing embodiments) may be described below.
Some embodiments of the present invention are now described, by way of example only, and with reference to the accompanying drawings. The same reference number represents the same element or the same type of element on all drawings.
The figures and the following description illustrate specific exemplary embodiments of the invention. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described or shown herein, embody the principles of the invention and are included within the scope of the invention. Furthermore, any examples described herein are intended to aid in understanding the principles of the invention, and are to be construed as being without limitation to such specifically recited examples and conditions. As a result, the invention is not limited to the specific embodiments or examples described below, but by the claims and their equivalents.
However, while the crowned roller 210 reduces lateral shifting of a web, a new web with a smaller or larger width than a previous web will center itself at the same location as the previous web and therefore have a different edge alignment within a printing system. Because of this, crowned rollers of previous systems cannot be used in edge-justified printing systems. An edge justified printing system configures components of the printing system (e.g., printheads, upstream/downstream components, etc.) to align with respect to an edge, or side, of a web of print media that travels through the printing system.
The crowned roller 430 is any type of roller with an uneven profile. The apex 432, although shown in
Printing system 400 comprises any system, component, or device operable to mark a web 420 of print media in an edge justified fashion. As discussed above, various components of an edge-justified printing system, such as printheads, are aligned with respect to an edge of the web 420. As such, in an edge-justified printing system, webs with different width sizes have a common lateral location of a respective common edge despite the change in web width size.
A lateral location is some point along a lateral direction of the printing system 400, the lateral direction being orthogonal to the direction of travel of the web (i.e., orthogonal to the length of the web, and parallel to the width of the web). The particular reference point and lateral distance used to define a lateral location of the margin 440 is a matter of design choice. Additionally, the side or common edge (i.e., right or left edge) of the webs of varying width sizes that is aligned with the margin 440 is a matter of design choice.
The sensor 460 comprises any system, component, or device operable to detect a lateral location of one or more edges of the web 420 with respect to the margin 440. For example, the sensor 460 can comprise a laser, pneumatic, photoelectric, ultrasonic, infrared, optical, or any other suitable type of sensing device. The sensor 460 can be placed upstream or downstream of other components (e.g., crowned roller 430 or adjustment mechanism 470) as desired.
The controller 450 comprises any system, component, or device operable to control the adjustment mechanism 470 based on the lateral location of the web 420 detected by sensor 460. Controller 450 can be implemented, for example, as custom circuitry, as a processor executing programmed instructions stored in an associated program memory, or some combination thereof. The adjustment mechanism 470 comprises any system, component, or device operable to adjust the lateral position of web of the apex 432 of the crowned roller 430. Illustrative details of the operation of printing system 400 will be discussed with regard to
In step 502, a margin 440 of the printing system 400 is identified. As discussed above, the margin 440 is a target alignment point for an edge of the web 420 as it travels through the printing system 400. The margin 440 may be inherent to a printing system 400 and/or determined or set by an operator and/or the controller 450 of the printing system 400.
In step 504, the sensor 460 detects that the edge of the web 420 is not aligned with the margin 440. Then, at step 506, the adjustment mechanism 470 adjusts a lateral position of the apex 432 of the crowned roller 430 to align the edge of the web 420 with the margin 440. In one embodiment, the adjustment mechanism 470 is directed automatically by the controller 450 which shifts the crowned roller 430 and its apex 432 in a lateral direction based on information received from the sensor 460. Additionally or alternatively, the adjustment mechanism 470 is directed manually by a user of the printing system 400.
One or more steps of method 500 may repeat multiple times during printing. For example, the sensor 460 and controller 450 may continually detect and adjust the lateral location of the edge of the web 420 during printing to maintain edge alignment with the margin 440 and compensate for lateral shifts in the web 420. Alternatively or additionally, one or more steps of the method 500 may be triggered by a change of width of the web 420 of the printing system 400.
In one embodiment, the controller 450 may receive input from a user or the sensor 460 that a new web and/or web width that has been placed in the printing system 400. In response, the controller 450 may pause print operation and direct an appropriate lateral shift of the apex 432 to reposition an edge of the new web with the margin 440. Additionally, the controller 450 may resume print operation when the new web has been aligned with the margin 440.
The controller 450 may also be configured to activate or deactivate printheads of the printer 410 in accordance with the change in web width. For example, suppose a wide web replaces a narrow web in the printing system. The controller 450 may align a side of the wide web with the margin and then activate printheads on the opposite side of the aligned edge that were unused for the narrow web. When the narrow web replaces the wide web, the controller 450 may deactivate printheads in accordance with the narrower, edge-justified printing area. Further description and additional features may be found in the examples described below.
In the following examples, additional processes, systems, and methods are described in the context of a printing system that adjusts a lateral position of the apex 432 of a crowned roller 430 for edge-justified printing.
It is assumed, for the sake of the embodiment, that the web 650 is edge-justified at a lateral location such that the edge of the left side of the web 650 is a lateral distance e from the left side of the frame 630 of a printing system. In other words, the margin is located at lateral distance e from one side of the frame 630 and aligns each web with respect to a common left edge. It will be appreciated, however, that the particular web edge and frame side (i.e. right or left) and margin reference point (i.e., frame 630) are merely exemplary for the purposes of explanation and are not intended to be limiting.
At element 610, the web 650 is centered about the apex 432 in the middle of the frame 630 (e.g., 1/2w). Also, with respect to the left side of the frame 630, the center of the web 650 is located at a distance (e+1/2p). With the apex 432 of the crowned roller 430 located at this position, the edge of web 650 is aligned at lateral distance e for edge-justified printing. However, when a new web with a differently manufactured web width size (e.g., web 660 with width 2p in element 620) is positioned in the exemplary crowned roller system, the apex 432 is laterally re-positioned by the controller 450 and/or the adjustment mechanism 470 to maintain a constant edge alignment at margin e of the new web 660. In this example, since the width of web 660 is twice that of web 650, when the left edge of web 660 is aligned with the margin e, the web center 670 is located at a lateral distance of (e+1/2(2p)). As such, the controller 450/adjustment mechanism 470 translates the apex 432 of the crowned roller 430 to the right a distance of (1/2p) so that the edge of web 660 is edge-justified to the margin e despite the change in web width size.
Further exemplary embodiments of a laterally translating apex of a crowned roller will be described in
In another embodiment, such as in element 720, the adjustment mechanism 470 shifts the apex of the crowned roller to the right by a distance (1/2p) to accommodate a new web width 2p by adjusting the crowned roller 430 along the longitudinal axis of a non-translating shaft 760. The non-translating shaft 760 is laterally affixed in the frame 630 and the crowned roller 430 translates along the non-translating shaft 760 under the force of the adjustment mechanism 470. The non-translating shaft 760 may be rotatable and/or driven or alternatively be non-rotatable. Adjustment mechanism 470 may be manual or directed by a controller 450 receiving edge alignment information from one or more sensors.
In an alternative embodiment, the inner core 810 is laterally adjustable within the frame 630 and the crowned sleeve 820 is laterally attached such that it translates with the inner core 810. As above, the crowned sleeve 820 may rotate around the inner core 810 for web transport, or alternatively, the inner core 810 and crowned sleeve 820 may rotate together about a shaft attached to the frame 630. In any case, continuing with the example where web 660 with width 2p replaces web 650 with width p, the apex (being formed by the profile of the crowned sleeve 820) is adjusted to the right a lateral distance (1/2p) by the adjustment mechanism 470 so that a common edge of the webs 650/660 is aligned with a margin. Adjustment mechanism 470 may be manual or directed by a controller 450 receiving edge alignment information from one or more sensors.
Embodiments disclosed herein can take the form of software, hardware, firmware, or various combinations thereof. In one particular embodiment, software is used to direct a processing system of controller 450 to perform the various operations disclosed herein.
Computer readable storage medium 1112 can be an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor device. Examples of computer readable storage medium 1112 include a solid state memory, a magnetic tape, a removable computer diskette, a random access memory (RAM), a read-only memory (ROM), a rigid magnetic disk, and an optical disk. Current examples of optical disks include compact disk-read only memory (CD-ROM), compact disk-read/write (CD-R/W), and DVD.
Processing system 1100, being suitable for storing and/or executing the program code, includes at least one processor 1102 coupled to program and data memory 1104 through a system bus 1150. Program and data memory 1104 can include local memory employed during actual execution of the program code, bulk storage, and cache memories that provide temporary storage of at least some program code and/or data in order to reduce the number of times the code and/or data are retrieved from bulk storage during execution.
Input/output or I/O devices 1106 (including but not limited to keyboards, displays, pointing devices, etc.) can be coupled either directly or through intervening I/O controllers. Network adapter interfaces 1108 may also be integrated with the system to enable processing system 1100 to become coupled to other data processing systems or storage devices through intervening private or public networks. Modems, cable modems, IBM Channel attachments, SCSI, Fibre Channel, and Ethernet cards are just a few of the currently available types of network or host interface adapters. Display device interface 1110 may be integrated with the system to interface to one or more display devices, such as printing systems and screens for presentation of data generated by processor 1102.
Although specific embodiments were described herein, the scope of the invention is not limited to those specific embodiments. The scope of the invention is defined by the following claims and any equivalents thereof.
