Patent Application
20130153618
The present invention generally relates to printing systems and more particularly to a turnover module suitable for use in printing systems and methods for transporting the print media.
Continuous web printing allows economical, high-speed, high-volume print reproduction. In this type of printing, a continuous web of print media, such as paper or other substrate material, is fed past one or more printing subsystems or modules that form images by applying one or more colorants onto the surface of the print media. When the print media is to be printed on both sides, a turnover module is included within or between two printing modules. The turnover module includes one or more stationary turnbars that typically have an ultra-high density polyethylene tape around the exterior surface of the turnbars to reduce the sliding friction of the print media as it wraps over a turnbar. The ultra-high density polyethylene tape reduces the friction of most types of print media but can increase web tension through the turnover module. When the web tension is sufficiently high, the print media can tear or break. Also, with certain types of print media, the turnbar friction can be high enough to cause the web tension to be greater than the drive capacity of the driven rollers. Transportation of the print media through the print system ceases when the web tension is higher than the drive capacity.
One technique used to reduce the web tension in the turnover module is the use of a cushion of air between the turnbar and the print media. Pressurized air or gas is introduced into the stationary turnbar to force the air or gas out of holes formed around the entire perimeter of the turnbar. The air forms a cushion at the area of contact between the print media and the turnbar such that the print media does not contact the surface of the turnbar. The air cushion, however, can cause web wander due to the print media “floating” around the entire turnbar. Web wander is undesirable because it reduces the accuracy of the print process and requires tracking of the print media to be re-established with the use of a web guide device or alternative method.
According to one aspect, a turnbar for use in a turnover module in a printing system includes one or more air-cushioned sections and one or more friction sections. Each air-cushioned section includes holes formed in a portion of a perimeter of the turnbar. Each friction section includes a friction-inducing material disposed over or affixed to another portion of the perimeter of the turnbar. Air or gas is output through the holes to produce a cushion of air or gas between a print media and the air-cushioned section.
According to another aspect, the turnbar can include one or more pistons disposed within the turnbar for adjusting airflow through at least one air-cushioned section. As an alternative to a piston, or in addition to the one or more pistons, a movable sleeve can be positioned either in the interior of, or over the exterior of, the turnbar to block the air holes of the turnbar and selectively control the size of one or more air-cushioned sections.
According to another aspect, a turnover module can include one or more turnbars, where one or more of the turnbars includes one or more air-cushioned sections, wherein each air cushioned section includes holes in a portion of a perimeter of the turnbar, and one or more friction sections each including a friction-inducing material disposed over another portion of the perimeter of the turnbar.
According to another aspect, at least one turnbar in the turnover module can include one or more pistons disposed within the turnbar for adjusting airflow through at least one air-cushioned section. As an alternative to a piston, or in addition to the one or more pistons, a movable sleeve can be positioned either in the interior of, or over the exterior of, the turnbar to block the air holes of the turnbar and selectively control the size of one or more air-cushioned sections.
According to another aspect, a method for transporting a print media over a turnbar in a turnover module in a printing system includes outputting air or gas through one or more air-cushioned sections in the turnbar, where each air cushioned section includes holes formed in a portion of a perimeter of the turnbar. The amount of the air or gas output from the air-cushioned section can be adjusted. For example, the amount of the air or gas output from the air-cushioned section can be adjusted based on one or more characteristics of the print media, including, but not limited to, the width or thickness of the print media.
Embodiments of the invention are better understood with reference to the following drawings. The elements of the drawings are not necessarily to scale relative to each other. Like numbers indicate like parts throughout the views.
The present description will be directed in particular to elements forming part of, or cooperating more directly with, apparatus in accordance with the present invention. It is to be understood that elements not specifically shown or described may take various forms well known to those skilled in the art.
In the context of the present disclosure, the term “continuous web of print media” relates to a print media that is in the form of a continuous strip of media as it passes through the printing system from an entrance to an exit thereof. The continuous web of print media itself serves as the receiving print medium to which one or more printing ink or inks or other coating liquids are applied in non-contact fashion. This is distinguished from various types of “continuous webs” or “belts” that are actually transport system components rather than receiving print media and that are typically used to transport a cut sheet medium in an electrophotographic or other printing system. The terms “upstream” and “downstream” are terms of art referring to relative positions along the transport path of a moving web; points on the web move from upstream to downstream.
Referring now to the schematic side view of
The first printing module 102 and the second printing module 104 also include a web tension system that serves to physically move the print media 112 through the printing system 100 in the feed direction 114 (left to right as shown in the figure). The print media 112 enters the first printing module 102 from a source roll (not shown) and the linehead(s) 106 of the first module applies ink to one side of the print media 112. As the print media 112 feeds into the second printing module 104, a turnover module 116 is adapted to invert or turn over the print media 112 so that the linehead(s) 106 of the second printing module 104 can apply ink to the other side of the print media 112. The print media 112 then exits the second printing module 104 and is collected by a print media receiving unit (not shown).
First printing module 102 has a support structure that includes a cross-track positioning mechanism (A) for positioning the continuously moving web of print media in the cross-track direction, that is, orthogonal to the direction of travel and in the plane of travel. In one embodiment, cross-track positioning mechanism (A) is an edge guide for registering an edge of the moving media. A tensioning mechanism (SW), affixed to the support structure of first module 102, includes structure that sets the tension of the print media.
Downstream from the first printing module 102 along the path of the of print media 112, the second printing module 104 also has a support structure similar to the support structure for first printing module 102. Affixed to the support structure of either or both the first or second module is a kinematic connection mechanism that maintains the kinematic dynamics of the print media 112 in traveling from the first printing module 102 into the second printing module 104. Also affixed to the support structure of either the first or second module are one or more angular constraint structures for setting an angular trajectory of the print media 112.
Table 1 that follows identifies the lettered components used for print media transport as shown in
The first angular constraint is provided by in-feed drive roller B. This is a fixed roller that cooperates with a drive roller in the turnover module 116 and with an out-feed drive roller N in second printing module 104 in order to move the print media 112 through the printing system 100 with suitable tension in the feed direction 114. The tension provided by the preceding S-wrap serves to hold the print media 112 against the in-feed drive roll. Angular constraints at subsequent locations downstream along the print media 112 are provided by rollers that are gimbaled so as not to impose an angular constraint on the next downstream media span.
Although
And although the printing system shown in
The print media 112 enters along the input path 204 with ink or another liquid jetted onto a front side of the print media 112. In
The print media 112 then wraps around stationary turnbar 200 and passes to unit 208, where the print media wraps around a bar (not show) included in unit 208. The print media 112 exits unit 208 front side up, as shown in region 210. The print media 112 then wraps around stationary turnbar 202 and is directed along the output path 206. The print media 112 has now been inverted or turned over (see region 212) and the back side of print media 112b is positioned to receive ink from the linehead(s) in the next printing module (e.g., printing module 104 in
Referring now to
Air-cushioned section 502 introduces a cushion of air or gas 600 (
Although
Included within turnbar 700 is piston 710. Piston 710 is adapted to slide back and forth within turnbar 700, allowing the size of air-cushioned section 702 to be variable and customized for different types of print media 708. Increasing or decreasing the size of air-cushioned section 702 changes the number of holes 706 that output pressurized air or gas, thereby increasing or decreasing the amount of air or gas output by air-cushioned section 702.
Although
Moreover, as an alternative to a movable piston, or in addition to a movable piston, a movable sleeve can be positioned either in the interior of, or over the exterior of, the turnbar and used to block the air holes of the turnbar and selectively control the size of air-cushioned section 702. This allows the amount of air output from the air-cushioned section to be variable and customized for different types of print media.
Referring now to
If the flow of air or gas is to be adjusted, the process passes to block 802 where the adjustment is made. Once the adjustment is complete, or if the flow of air or gas is not adjusted at block 800, the method passes to block 804 where the print media is transported into a turnover module in a printing system. As the print media passes through the turnover module, air or gas is output from one or more air-cushioned sections formed in at least one turnbar in the turnover module (block 806). The air or gas output from the air-cushioned section or sections causes the print media to float over the air-cushioned section or sections. The friction section or sections produces a sufficient amount of friction between the print media and the turnbar that maintains web stability without inducing web wander.
A determination is made at block 808 as to whether or not the flow of air or gas is to be adjusted. Block 806 provides continuous or intermittent monitoring of the flow of air or gas from the air-cushioned section or sections disposed in at least one turnbar in the turnover module. The flow of air or gas can be adjusted when needed during a print operation.
If the flow of air or gas is to be adjusted at block 808, the process passes to block 810 where the flow is adjusted. As discussed earlier, the adjustment can be based on one or more factors. The process then returns to block 806.
If the flow of air or gas is not to be adjusted at block 808, the method passes to block 812 where a determination is made as to whether or not the print operation is complete. If not, the process returns to block 806.
The blocks shown in
The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention. And even though specific embodiments of the invention have been described herein, it should be noted that the application is not limited to these embodiments. In particular, any features described with respect to one embodiment may also be used in other embodiments, where compatible. The features of the different embodiments may be exchanged, where compatible.
1. A turnbar for use in a turnover module can include an air-cushioned section that includes holes formed in a portion of a perimeter of the turnbar, and a friction section that includes a friction-inducing material affixed to another portion of the perimeter of the turnbar. The friction section can be positioned adjacent to, or around, the air-cushioned section.
2. The turnbar in clause 1 can further include another air-cushioned section that includes holes formed in a different portion of the perimeter of the turnbar.
3. The turnbar as in clause 2, where an area of one air-cushioned section is different from an area of the other air-cushioned section.
4. The lumbar in any one of clauses 1-3 can further include at least one piston inside the turnbar for adjusting a size of one or more air-cushioned sections.
5. The turnbar in any one of clauses 1-3 can further include at least one movable sleeve for adjusting a size of one or more air-cushioned sections. The movable sleeve can be disposed in an interior of the turnbar or over the exterior of the turnbar.
6. The lumbar as in any one of clauses 1-5, where an area of one or more air-cushioned sections is divided into zones and the output of air or gas from each zone is controlled individually.
7. A turnover module can include one or more turnbars, where at least one of the one or more turnbars includes one or more air-cushioned sections and one or more friction sections. Each air cushioned section includes holes formed in a portion of a perimeter of the turnbar. Each friction section includes a friction-inducing material disposed over another portion of the perimeter of the turnbar.
8. The turnover module as in clause 7, where an area of one air-cushioned section is different from an area of another air-cushioned section.
9. The turnover module in clause 7 or clause 8 can further include at least one piston inside at least one of the one or more turnbars for adjusting a size of a respective air-cushioned section.
10. The turnover module in clause 7 or clause 8 can further include at least one movable sleeve for adjusting a size of one or more air-cushioned sections. The sleeve can be disposed in the interior of the turnbar or around the exterior of the turnbar.
11. The turnover module as in any one of clauses 6-10, where an area of the one or more air-cushioned sections is divided into zones and the output of gas or air from each zone is controlled individually.
12. A method for transporting a print media over a turnbar in a turnover module in a printing system includes outputting air or gas through holes formed in an air-cushioned section in the turnbar, where the air-cushioned section is formed in a portion of a perimeter of the turnbar, and adjusting a flow of air or gas output from air-cushioned section.
13. The method as in clause 12, where the flow of air or gas output from the air-cushioned section is adjusted based on one or more properties of the print media.
14. The method as in clause 12, where at least one property of the print media includes a width of the print media.
15. The method as in clause 13 or clause 14, where at least one property of the print media includes a thickness of the print media.
This patent application is related to U.S. patent application Ser. No. ______(Docket K000453), entitled “TURNBAR AND TURNOVER MODULE FOR PRINTING SYSTEMS” filed concurrently herewith.
