In accordance with one aspect of the present exemplary embodiment, a system transports paper to prevent stubbing within a printing machine. The paper path facilitates transport of one or more sheets of paper from the first end to the second end, each sheet of paper has a leading edge. A first entry point is located between the first end and the second end that allows one or more sheets to enter the paper path in succession. A first nip is adjacent to the first entry point to direct the leading edge of the one or more sheets away from the first entry point. A second entry point is located a distance from the first entry point that allows one or more sheets to enter the paper path. A second nip is adjacent to the second entry point to direct the leading edge of the one or more sheets away from the second entry point. A gateless diverter directs the one or more sheets of paper through the paper path which includes a convex section that is adjacent to a concave section to divert the leading edge of each of the one or more sheets away from the first entry point and the second entry point. The one or more sheets of paper are advanced to the convex section via the first nip in advance to the concave section to the second nip.

BACKGROUND

The present disclosure broadly relates to printing systems and, more particularly, to paper sheet transport within printing systems. A gateless diverter consists of adjoining concave and convex elements to direct the leading edge of paper in transport away from potential stubbing points in a paper path.

Known printing systems are generally capable of marking sheets of media of a variety of types (e.g., plain paper, bond paper, recycled paper, card stock, and transparencies), sizes (e.g., letter, legal, A3, A4) and/or in different orientations (e.g., long-edge feed, short-edge feed). Typically, a known printing system will include at least one media tray capable of receiving a bulk quantity (e.g., stack, package, ream) of sheets of media and introducing the bulk quantity to a suitable sheet feeding system or mechanism to advance individual sheets in an known manner. Often, known printing systems will include numerous media trays with each tray receiving a different type, size and/or orientation of sheet media.

Many known printing systems are capable of determining which particular one of a number of pre-defined sizes and/or orientations of sheet media have been loaded into the storage tray. Unfortunately, these and other known printing systems and media tray arrangements suffer from problems and disadvantages that can, in certain applications, limit the use and/or effectiveness of the same. Similarly, the transport of paper sheets within a printing system can pose difficulties due to stubbing and/or jamming within a paper path.

In one example, paper is transported within the printing system via a path located within a door. In particular, the door paper path transports one or more sheets vertically from a tray module to an image marking engine (IME). These sheets can be introduced from both a multi-sheet inserter (MSI) and a paper feed platform (PFP) and can act as an inverter for sheets entering from a duplex path of the IME. The proximity of the MSI and PFP entry chutes, coupled with the offset of nips within the paper path, provide potential stubbing points when feeding sheets from the tray module. Actuated diverters have traditionally been employed in conventional print system designs. Diverters, however, add cost to print system designs since extra components are required. Moreover, actuated diverters wear down mechanically and are unreliable for long term use which is required of most printing systems. What are needed are systems and methods that overcome the above referenced difficulties associated with paper transport within a print system.

BRIEF DESCRIPTION

In one aspect, a system transports paper to prevent stubbing within a printing machine. The paper path has a first end and a second end and a width defined by a first wall located in opposition to a second wall. The paper path facilitates transport of one or more sheets of paper from the first end to the second end, each sheet of paper has a leading edge. A first entry point is located between the first end and the second end that allows one or more sheets to enter the paper path in succession. A first nip is adjacent to the first entry point to direct the leading edge of the one or more sheets away from the first entry point. A second entry point is located a distance from the first entry point that allows one or more sheets to enter the paper path. A second nip is adjacent to the second entry point to direct the leading edge of the one or more sheets away from the second entry point. A gateless diverter directs the one or more sheets of paper through the paper path. The gateless diverter includes a convex section that is adjacent to a concave section to divert the leading edge of each of the one or more sheets away from the first entry point and the second entry point. The one or more sheets of paper are advanced to the convex section via the first nip in advance to the concave section to the second nip.

In another aspect, a system is employed to transport paper within a printing machine. A paper path that has a first end and a second end and a width defined by a first wall located in opposition to a second wall facilitates transport of paper from the first end to the second end. A first entry point is located at an angle to the paper path that allows one or more sheets of paper to enter the paper path in succession. A convex section is adjacent to the first entry point that directs the leading edge of the one or more sheets away from the first entry point. A second entry point is located a distance from the first entry point that allows paper to enter the paper path. A concave section is located between the convex section and the second entry point to direct the leading edge of the one or more sheets of paper away from the second entry point. A ramp is located adjacent to each of the first entry point and the second entry point, wherein the ramp is a recessed portion of the side wall of the paper path that is shared with each of the first entry point and the second entry point.

In yet another aspect, a method is employed to transport paper to avoid stubbing within a printing machine. A sheet of paper is received into a first end of a paper path, the sheet of paper has a leading edge. The sheet of paper is advanced through the paper path via a first nip to a second nip, wherein the first nip and the second nip each include at least one pair of rollers. The leading edge of the sheet is directed away from the first entry point via the second nip, the first entry point is located on the side of the paper path. The sheet of paper is advanced to the first entry point through a convex section in a concave section of the paper path, wherein the convex section is located adjacent to the concave section. The leading edge of the sheet is directed away from the second entry point via a third nip, the second entry point is located on the side of the paper path.

DETAILED DESCRIPTION

The embodiments described herein relate to an ‘S’ shaped gateless diverter for transport of paper sheets within a printing machine. A novel curved section of a paper path starts just prior to a first entry point (e.g., for a paper feed platform chute) and ends at just after a second entry point (e.g., for a multiple sheet inserter chute). The radii of the concave/convex sections and transition points are designed to ensure that curled sheets being fed from a multiple tray module avoid stubbing on exit chutes of one or more ancillary feeders. This ensures that the leading edge of a sheet is directed towards the right hand paper path away from the chutes. Both the proximity of the first and second entry points, coupled with the fact that they are offset, ensures that potential stubbing issues are produced if a straight paper path is employed. This avoids the requirement for actuated diverter gates.

With reference toFIG. 1, a paper path100is illustrated that allows sheets of paper to be fed from a number of trays in a print system without stubbing. In one example, the paper path100can transport paper sheets from an entry point (e.g., a multi-tray module)104to an entry/exit point (e.g., an image marking engine)106. Entry points108and110allow paper sheets to be fed into the paper path100at additional locations to accommodate various desired operations. As illustrated, the entry points108and110inherently include one or more potential stubbing points (e.g., tips) based on an angle of entry into the paper path100. Pages can also be stubbed if a paper path includes excessively acute angles and/or radii that are overly restrictive relative to the size of sheets that are fed through a paper path.

In conventional printing machines, there are a number of potential stubbing points associated with a paper path. First, all sheets fed from a multiple (e.g., three) tray module are transported vertically upwards through a section of a paper path towards the IME. As the sheet passes the entry points108and110, it must avoid stubbing on the entry chutes associated therewith. Stubbing is potentially a problem for three different types of curl: down curled sheets in the process direction, cross process curled sheets, or bowl curled sheets (a combination of both process and cross process curl).

Secondly, sheets fed from entry points108and110must avoid stubbing on the right side of the paper path as illustrated inFIG. 1. The worst case for this problem is down-curled media stubbing on the right hand guide. Third, sheets fed from entry point106(e.g., a duplex path) must avoid stubbing with both the entry points108and110as the sheet is transported from the top (e.g., IME) of the paper path100. The leading edge of sheets from the entry point106in the duplex path must pass both the entry points108and110in order to enable larger (e.g., A3) sheets to be inverted. In particular, out-curled sheets pose a significant problem in terms of stubbing. It is to be appreciated that although paper sheets are discussed herein, substantially any material can be employed for sheets including acetate, velum, etc.

In order to insure stub free travel in either direction along the paper path100, a concave section112and a convex section114are positioned adjacent to each other to create an ‘S’ shaped gateless diverter116. As a sheet passes entry points108and110, the concave portion112and convex section114direct the leading edge of a sheet (not shown) away from potential stubbing points. In one aspect, the gateless diverter116reduces cross-process and bowl curl of pages that conventionally causes paper to stub on one or more obstacles within a paper path.

It is to be appreciated that substantially any number of concave sections and corresponding adjacent convex sections can be employed to eliminate stubbing within the paper path100. Moreover, the radii and angle of direction of transport can vary to accommodate one or more metrics associated with printing such as paper size, paper thickness, print application, etc. The location of such adjacent concave and convex sections can be related to particular features of the paper path100such as one or more stubbing points, entry chutes, and path distance for example.

In an exemplary operation, a sheet enters the paper path100from one of four entry points104,106,108, and110. Sheets that enter the paper path100via108are illustrated as path1; sheets that enter the paper path100via110are illustrated as path2; sheets that enter the paper path100via104are illustrated as path3; and sheets that enter the paper path100via106are illustrated as path4. In addition, four nips,126,128,130, and132are located throughout the paper path100to facilitate transport of paper sheets as they pass therethrough. In one example, each nip includes a pair of rollers (or equivalent) that rotate in an appropriate direction when in contact with a paper sheet.

In one example, the entry point108receives one or more sheets from a multiple sheet inserter (MSI). The one or more sheets are transported through a left hand door of a printing system to an image marking engine (IME)122via exit/entry point106. In another example, one or more sheets are received by the paper path100via entry point110from a paper feed platform (PFP) that docks to the side of the printing machine. The one or more sheets are transported vertically through a door to the IME.

Alternatively or in addition, one or more sheets are fed to the paper path100via entry point104from a three tray module (3TM). The one or more sheets travel vertically through a door past the entry points108and110to the IME122via entry/exit point106. Once the sheets are processed by the IME122, they can re-enter the paper path100(via a duplex path) again through entry point106. In one example, the one or more sheets are longer than a standard (e.g., 8½″−11″, A4) size. Such an excessive length can cause sheets to become stubbed on one or more obstacles within the paper path100.

For instance, for an A3 or 11″×17″ sheet, the lead edge can travel down the paper path past entry point108. In conventional systems, as a sheet passes an entry point on a paper path, the leading edge can become stubbed. This is especially true as the sheet passes between entry points (e.g., between entry points108and110). In order to mitigate such stubbing, the concave section112and the convex section114are adjacently placed between the entry points to divert the leading edge of one or more sheets away from the entry points108and110as they pass. The nips126and128can be placed adjacent to the entry points108and110respectively to facilitate transport of one or more sheets through the paper path100and/or to prevent stubbing.

FIG. 2illustrates the nip126that is utilized adjacent to entry point108as shown inFIG. 1above. The nip126includes a roll204and a roll206. Although a single roll pair204and206is illustrated, it is to be appreciated that a plurality of nips and associated roll pairs can be located across the width of the paper path100. The rolls204and206can be comprised of substantially any material such as rubber, plastic, steel, etc. to facilitate optimum contact with the paper sheets that are passed therethrough.

In one example, a sheet is transported past the entry point108via the nip126and past the entry point110via the nip128. Because the entry points108and110are located on the left hand side of the paper path100, the nips126and128are rotated as the paper sheets enter to divert the sheet to the right hand side of the paper path. In this manner, the leading edge of the papersheet is moved as far from possible from the entry points to minimize the possibility of the sheet stubbing and/or directed down an undesired path.

To direct the sheet in a desired direction, the rolls204and206can be positioned in particular location relative to each other or one or more features of the paper path100. For example, the roll204can be placed such that the diameter of the roll204is lower relative to the diameter of the roll206. In addition, the center line of the rolls (e.g., location wherein the rolls204and206are in the closest proximity to one another), can be offset from the center line of the paper path. For instance, center line of the rolls204and206can be located offset to the right relative to the center line of the paper path. In this manner, the leading edge of the sheet can be directed to the right based on the relative force of the rolls204and206on the sheet as it passes through the nip126.

The tip210is the point of divergence between the paper path100and the entry point108. In one embodiment, the tip210is recessed from the paper path100to avoid sheet (e.g., duplex) stubbing or travelling down the incorrect path. Such tip210location provides a greater clearance for the leading edge of a sheet to pass the entry point210unencumbered. To further enhance control of the leading edge location within the paper path, a ramp216is situated just past the entry point108within the paper path100. The ramp216is a recessed portion of the side wall of the paper path that is shared with the entry point108. The ramp216can have substantially any radius relative to a center point220. This radius can be based at least in part upon the paper size, paper thickness and printing operation performed within the printing machine.

In many printing machines, actuated diverters are employed to ensure that paper sheets travel along an intended path (e.g., the paper path100). The paper path100must be robust to all potential stubbing points by taking into account up-curl, down-curl and cross process curl of the paper sheets.FIG. 3illustrates an upper door310and a mid door312of a printing machine that utilize the paper path100to transport paper sheets therethrough. Similarly,FIG. 4illustrates a paper path baffle410employed with a printing machine that includes the paper path100. It is to be appreciated that the gateless diverter116can be employed in substantially any location within substantially any printing machine.

In one example, the upper door310, the mid door312, and the paper path baffle410can be center registered wherein all the nip pairs through each component are double rolls located in the center of the paper path. As a result, the extreme edges of the sheet are not controlled by the roller pairs which creates a number of potential stubbing points caused by cross process curl. Conventionally, gateless diverters have been employed in printing machines to overcome such deficiencies. However, a gateless diverter has not been contemplated with these components in the areas of a printing machine illustrated inFIGS. 3 and 4. One reason is due to the proximity of entry points108and110(e.g., MSI and PFP chutes) and the fact that they are slightly offset.

FIG. 5illustrates a dimensioned view of the paper path100. It is to be appreciated that the dimensions are for illustrative purposes only and one or more dimensions can be modified within the scope of the embodiments described herein. A three-dimensional model was employed to verify a design for cross process and bowl curl. In particular, a path taken by extremities of sheets that are not controlled by the central nips. In one approach, sheets are fed with these three different types of curl to a stress level of 100 mm radius of curvature (e.g., 12 mm flat curl for a 60 gsm sheet). All stubbing points were eliminated.

Further analyses ensured that two other potential issues with the design were eliminated. First, the severity of the radii of the concave/convex sections (e.g., convex section112and114) were minimized to ensure Nip G in the simplex direction and Nip E in the duplex direction have sufficient drive to feed heavyweight sheets through the paper path100. Software was employed to predict the slip between the Nip G and Nip E. The slip levels that were predicted were not significant.

The contact forces between the sheet and guides were also predicted and checked against the image-marking limit for solid ink. The speed of the rolls of Nip E and Nip F were set to their worst case levels to either create a buckle between the nips or to stretch the sheet across the guides. The contact forces were checked against recommended guidelines for solid ink to PC-ABS, ABS and Steel to ensure that the image on the duplexed sheets was not damaged. The forces were well within the limits for all three materials.