The invention relates to the field of printing systems, and in particular, to dryers of printing systems.
Businesses or other entities having a need for volume printing typically use a production printing system capable of printing hundreds of pages per minute. A web of print media, such as paper, is stored in the form of a large roll and unraveled as a continuous sheet. During printing, the web is quickly passed underneath printheads which discharge small drops of ink at particular intervals to form pixel images on the web. The web may then be dried and cut to produce a final printed product. Since production printers output high quality images at high speed, it is important that the drying process of the web is quick, effective, and efficient.
Embodiments described herein provide dryer rollers of a print system with increasing contact area. After initially entering the dryer, a web of print media contacts initial rollers for a short distance/time. The contact area of the web with respect to subsequent dryer rollers gradually increases as the web travels through the dryer. Advantageously, the configuration utilizes the available heating power of the dryer rollers more efficiently by balancing heating duty cycle among the rollers.
One embodiment is a system that includes a dryer of a printing system. The dryer includes a turning device configured to rotate about an axis, and to guide a web of print media. The dryer also includes rollers configured to transport the web from an entrance of the dryer to the turning device. The rollers include a series of three or more rollers positioned in the dryer to consecutively increase an amount of contact area with the web as the web travels toward the turning device.
Another embodiment is a web handling system. The web handing system includes a turning device configured to rotate about an axis, and to guide a web of print media. The web handling system also includes rollers configured to transport the web from an entrance to the turning device. The rollers include a series of three or more rollers to consecutively increase an amount of contact area with the web as the web travels toward the turning device.
Yet another embodiment is a method of heating a web of print media. The method includes providing a turning device to guide the web in a dryer of a printer. Method further includes positioning rollers in the dryer to define a path for the web along the arc between an entrance of the dryer and the turning device. Method also includes increasing an amount of contact area of the web with three or more of the rollers as the web travels toward the turning device.
Yet another embodiment is a system that includes a dryer of a printing system. The dryer includes a turning device configured to rotate about an axis, and to guide a web of print media. The dryer also includes rollers configured to transport the web from an entrance of the dryer to the turning device. In one embodiment, the rollers are positioned such that an amount of contact area between the web and individual ones of the rollers increases on a moving average basis as the web travels toward the turning device. In another embodiment, each of the rollers consecutively increase an amount of contact area with the web as the web travels toward the turning device.
The above summary provides a basic understanding of some aspects of the specification. This summary is not an extensive overview of the specification. It is not intended to identify key or critical elements of the specification nor to delineate any scope of particular embodiments of the specification, or any scope of the claims. Its sole purpose is to present some concepts of the specification in a simplified form as a prelude to the more detailed description that is presented later. Other example 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. 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 embodiments and are included within the scope of the embodiments. Furthermore, any examples described herein are intended to aid in understanding the principles of the embodiments, and are to be construed as being without limitation to such specifically recited examples and conditions. As a result, the inventive concept(s) is not limited to the specific embodiments or examples described below, but by the claims and their equivalents.
After printing, the web 120 enters an enclosure 302 of dryer 300 at the dryer entrance 304 with a marked side 324 that is wet with an applied ink and an unmarked side 326 that does not have ink (or which has been previously marked and already dried). The web 120 may travel over one or more entrance rollers 370-372 before encountering the first rollers 350-359. The first rollers 350-359 transport (i.e., guide) web 120 along a first path of the arc in a first direction (e.g., clockwise direction or first circular direction). One or more of the first rollers 350-359 may be heated internally or externally for drying ink applied to the web 120. A roller (e.g., roller 359) among the first rollers 350-359 which is last along the arc turns web 120 toward drum 210. The web 120 then wraps around a circumferential portion of the drum 210 which applies further heat to the web 120.
After traveling around the drum 210, the web 120 encounters the second rollers 360-369. A roller (e.g., roller 369) among the second rollers 360-369 which is first to receive the web 120 from the drum 210 may be positioned adjacent to the last roller (e.g., roller 359) of the first rollers 350-359. Accordingly, rollers 369/359 may tension/transport the web 120 around a substantial circumferential portion of the drum 210 (e.g., wrap/contact angle of 300 degrees or more). The second rollers 360-369 transport web 120 along a second path of the arc in a second direction which is generally opposite from the first direction (e.g., counter-clockwise direction or a second circular direction opposite to the first circular direction). The second rollers 360-369 are positioned along the arc and radially between the first rollers 350-359 and the drum 210. After traveling the arc again in the reversed (i.e., opposite) direction, the web 120 may travel over one or more exit rollers 373-374 before leaving dryer 300 through the dryer exit 306 of the enclosure 302.
Although this configuration provides an increased path length in comparison with conventional drum-only dryers (and therefore an increased number of options for conditioning web with precise control), the increased number of heated elements may result in increased system power rating. Moreover, there may be an imbalance of power consumption across the rollers 350-359/360-369 and it may be difficult to define the correct temperature settings that achieve a desired heat profile of the web 120.
For example, initial heated rollers (e.g., first rollers 351-352) may consume power at a high rate to transfer heat to web 120 near room temperature, and later heated rollers (e.g., first rollers 357-359) may consume power at a low rate since web 120 is at a high temperature by the time it reaches those rollers. Moreover, it may be desirable for first rollers 350-359 to comprise common components (e.g., to make installation/maintenance of the dryer 300 easier) and thus have the same power output capability. However, if each of the first rollers 350-359 have relatively high output to match the capability for the initial rollers (e.g., first rollers 351-352) then some of the later rollers (e.g., first rollers 357-359) may be oversized for their use, resulting in the dryer 300 having a high system power rating but with relatively low utilization. Alternatively, if each of the first rollers 350-359 have relatively low output to match the capability for the later rollers (e.g., first rollers 357-359) then the initial rollers (e.g., first rollers 351-352) may not apply enough heat as desired for the heat profile of web 120.
The rollers 450-452 are arranged or spaced in a different configuration than that of the first rollers 350-359 of the dryer 300 described above. In particular, the rollers 450-452 are positioned such that a contact area of the web 120 increases for each subsequent roller 450-452 as the web 120 travels toward the turning device 410. In this context, a contact area is a circumferential contact area between the web 120 and one of the rollers 350-352. Contact area between web 120 and a roller is based on a wrap angle, the radius (or diameter) dimension of the roller and the width dimension of the web in contact with the roller. With a set of rollers that have a common radius and a web of fixed width, the contact area is then proportional to the wrap angle. For example, the web 120 has a relatively small first contact area 470 around initial roller 450 (e.g., nearest to entrance 404), a medium second contact area 471 around intermediate roller 451, and a relatively large third contact area 472 around last roller 452 (e.g., nearest to turning device 410). The rollers 450-452 are thus positioned such that a contact area of the web 120 increases for each subsequent roller as the web 120 travels toward the turning device 410.
This configuration enables improved power consumption and an improved heating profile of the web 120. For example, the initial roller 450 is able to operate with moderate power consumption because its limited contact area 470 (and therefore contact time) restricts the amount of heat transfer to the web 120 at a time in which the web 120 is at a relatively low temperature (e.g., room temperature). The last roller 452 is also able to operate with moderate power consumption because, although the web 120 has increased temperature and is closer in temperature to the last roller 452 as it initiates contact, the increased contact distance/time of contact area 472 enables the last roller 452 to impart a similar amount of heat transfer as that of the initial roller 450. By contrast, the dryer 300 of
After wrapping/turning around the turning device 410, the web 120 is tensioned by supports 460-461 as the web 120 travels from the turning device 410 to the exit 406. The supports 460-461 may comprise any element suitable to guide/tension the web 120. The supports 460-461 reverse the path of the web 120 between the turning device 410 and the exit 406. In some embodiments, the rollers 450-452 comprise first rollers, and the supports 460-461 comprise second rollers. In some embodiments, the supports 460-461 are curved surfaces suitable for guiding web 120 as it travels. As shown in
Additionally, as shown in
As also shown in
Positions of the supports 560-569 may correspond with the positions of the rollers 550-559. For example, support 560 corresponds with roller 559, support 561 corresponds with 558, and so on. Thus, the supports 560-569 may be positioned relative to one another such that a distance between adjacent ones of the supports 560-569 decreases as the web 120 travels from the turning device 410 and toward the exit 406 of the dryer 500. Furthermore, the supports 560-569 may be positioned relative to the rollers 550-559 such that an amount of contact area of the web 120 with the second circumferential portion of each of the rollers 550-559 increases for each subsequent roller as the web 120 travels from the turning device 410 and toward the exit 406 of the dryer 500. That is, the web 120 contacts a second circumferential portion of roller 559 a relatively small amount and gradually increases contact for subsequent rollers until it contacts a second circumferential portion of roller 550 a relatively large amount. The increasing contact/heat time of the web 120 with respect to the second pass across rollers 550-559 advantageously enables the web 120 to transfer heat back into the dryer 500 as it exits the dryer 500 with increasing temperature setpoints to reduce the output temperature of the web 120 and further improve drying efficiency.
An interlaced roller configuration refers to a relative position between a roller and a support. As earlier described, the supports 560-569 may occupy the spaces between the rollers 550-559 such that web 120 alternates contact with the supports 560-569 and rollers 550-559 as it travels in the second direction between the turning device 410 and the exit 406. The amount of overlap, or relative distance between a support and a roller along a direction perpendicular to web travel, imparts a corresponding amount of contact/heat between web 120 and the rollers 550-559 as the web 120 travels in the second direction. Though ink applied to the marked side 324 of web 120 may be sufficiently dry so as not to smear by the time it begins to contact the supports 560-569, it may be desirable for a number of reasons to further transfer heat to the web 120 with the rollers 550-559 as web 120 travels in the second direction to condition the web 120 for sufficient print/drying quality.
Thus, the web 120 may be dried via heated contact between the unmarked side 326 of web 120 and a first circumferential portion of each of the rollers 550-559 as the web 120 travels in the first circular direction along the arc. The web 120 may be further dried via heated contact between the marked side 324 of web 120 and a second circumferential portion of each of the first rollers 550-559 as the web 120 travels in the second circular direction along the arc in a reverse direction but which now interleaves in a zigzag pattern between the supports 560-596 and the rollers 550-559. The supports 460-469 may be configured to disengage to a non-interlacing position (e.g., such that supports do not guide web 120 to contact rollers 550-559) for paper threading, roller cleaning, a particular drying application, etc.) and/or adjust the amount of interlacing to cause a corresponding adjustment in contact area or heat applied to web 120.
As shown in
In one embodiment, the rollers 550-559 are positioned in the dryer 700 such that an amount of contact area between the web 120 and individual ones of the rollers 550-559 increases on a moving average basis as the web 120 travels toward the turning device 410. A moving average basis of a contact area may be defined at each roller as an average of the contact area of the web 120 at that roller and the contact area of the web at each of the previous rollers. As shown in
In other embodiments, one or more supplemental rollers that contact and transport the web 120 may be positioned within the series of rollers (e.g., rollers 550-554 or rollers 556-559). For example, one or more supplemental rollers may be located to contact the web between roller 550 and roller 551 (e.g., within the series of rollers 550-552) and/or between roller 556 and roller 557. The one or more supplemental rollers may provide supplemental transport guidance or drying of the web 120. Nonetheless, the series of rollers (e.g., rollers 550-554 or rollers 556-559) may consecutively increase web contact area regardless of the one or more supplemental rollers.
In step 802, the turning device 410 is provided to the dryer 600 to guide the web 120. In step 804, the rollers 550-559 are positioned in the dryer 600 to define a path for the web 120 between the entrance 404 and the turning device 410. In step 806, an amount of contact area of the web increases consecutively with three or more of the rollers 550-559 as the web 120 travels toward the turning device 410. In step 808, the distance between adjacent ones of the rollers 550-559 increases as the web 120 travels toward the turning device 410. In step 810, the supports 560-569 are positioned between the rollers 550-559 to reverse the path of the web 120 between the turning device 410 and the exit 406. The supports 560-569 may be adjusted via the movement mechanism 610 to adjust the contact time/amount on rollers 550-559 on the reverse path.
The particular arrangement, number, and configuration of components described herein is non-limiting and provided as example. Although specific embodiments were described herein, the scope of the inventive concepts is not limited to those specific embodiments. The scope of the inventive concepts is defined by the following claims and any equivalents thereof
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