Patent Application
20100096795
This disclosure generally relates to substrate (paper) feeders. It more particularly concerns a friction retard feeder that improves sheet separation.
Digital Printing using a variety of marking technologies such as: Electrophotographic, Liquid Ink Jet, Solid Ink Jet, is a well-known, commonly used method of copying or printing documents. As the market place moves away from only Black and White documents and includes more color images, the substrate media used to enhance color images employ a smoother surface finish or surface coatings. Composite substrates consisting of cellulous and polymer layers or synthetic substrates are becoming more common. When composite substrates and coated substrates are used, the probability that a substrate feeding apparatus will pull both a first substrate and an adjacent second substrate increases.
Marking machines typically include one or more substrate feeding systems. For example, the substrate feeding system might move paper from an input tray to a transfer station. Input trays used in lower cost printers typically employ a friction retard feed mechanism and a pivoting elevator plate to raise the substrate stack up to the feeding apparatus as substrates are removed from the substrate stack. Friction retard feeding mechanisms deflect the first substrate in the direction of the adjacent second substrate, which increases the face-to-face contact force between the first and second substrates. The face-to-face contact forces can drag the adjacent second substrate into the feeding mechanism with the first substrate. These contact forces between composite and coated substrates can be twenty times greater than uncoated substrates, resulting in composite substrates and coated substrates being multi-fed more frequently than uncoated substrates because of the increased face-to-face contact forces between the first substrate and the adjacent second substrate.
While prior art substrate feeding systems have been very successful, there exists a need for an improved substrate feeding system for coated and synthetic media characterized by fewer multiple sheet feedings.
According to aspects illustrated herein, there is provided a substrate feeding apparatus for feeding substrates from a substrate stack. The substrate feeding apparatus includes a nudger roll being selectively movable between a first position and a second position. In the first position, the nudger roll is in contiguous contact with a first substrate of the substrate stack for advancing the first substrate from the substrate stack. The first substrate having a lead edge and a trail edge, with the lead edge leading in a direction of advancement. In the second position, the nudger roll is not in contiguous contact with the substrate stack or the first substrate. A feed roll for further advancing the first substrate in the direction of advancement. A retard member forming a nip with the feed roll. The retard member is used for separating the first substrate from an adjacent second substrate. A guide baffle extending between the substrate stack and the nip, with the guide baffle configured to contact and guide, the first substrate as it advances in the direction of advancement from the nudger roll to the nip. The guide baffle provides an angular change in direction to the first substrate as the first substrate advances from the substrate stack to the nip. The guide baffle is configured such that as the lead edge of the first substrate enters the nip, the first substrate has portions thereof spaced from the guide baffle, with the spaced portions sagging towards the guide baffle to provide the first substrate with a concave profile. The nudger roll moves from the first position to the second position after the lead edge of the first substrate enters the nip.
According to other aspects illustrated herein, there is provided a printing machine having a substrate feeder. The printing machine includes a nudger roll selectively movable between a first position and a second position. In the first position, the nudger roll is in contiguous contact with a first substrate of a substrate stack for advancing the first substrate from the substrate stack, the first substrate having a lead edge and a trail edge, the lead edge leading in a direction of advancement. In the second position, the nudger roll overlaps the substrate stack but is not in contiguous contact with the substrate stack or the first substrate. A feed roll for further advancing the first substrate in the direction of advancement. A retard member forming a nip with the feed roll. The retard member being used for separating the first substrate from an adjacent second substrate. A guide baffle extending between the substrate stack and the nip, with the guide baffle configured to contact and guide, the first substrate as it advances in the direction of advancement from the nudger roll to the nip. The guide baffle is configured such that as the lead edge of the first substrate enters the nip, the first substrate has portions thereof spaced from the guide baffle, with the spaced portions sagging towards the guide baffle to provide the first substrate with a concave profile. The nudger roll moves from the first position to the second position after the lead edge of the first substrate enters the nip.
Additional features and advantages will be readily apparent from the following detailed description, the accompanying drawings and the claims. It is to be understood, however, that the drawings are designed as an illustration only and not as a definition of the limits of the disclosure.
Like reference symbols in the various drawings indicate like elements.
Referring to
As used herein, the phrase “printing machine” encompasses any apparatus, such as a digital copier, bookmaking machine, facsimile machine, and multi-function machine, which performs a printing outputting function for any purpose.
As used herein, the terms “substrate” and “substrate stack” include, for example, one or more of a usually flimsy physical sheet of paper, heavy media paper, coated papers, transparencies, parchment, film, fabric, plastic, or other suitable physical print media substrate on which information can be reproduced.
As used herein, a “feeding apparatus” encompasses any apparatus for separating and conveying one or more substrates from a stack of substrates into the substrate conveyance path inside a printing machine.
As used herein, the phrase “feed roll” refers to an article that advances the substrates in a “direction of advancement.”
As used herein, the phrase “direction of advancement” refers to a direction the substrates travel in being conveyed from a feeding apparatus to another location.
As used herein, the phrase “nudger roll” refers to an article that advances the substrates off the substrate stack in the direction of advancement.
As used herein, the phrase “lead edge” refers to the edge of a substrate that first moves in the direction of advancement.
As used herein, the phrase “trail edge” refers to the edge of a substrate opposite the lead edge.
As used herein, the phrase “contiguous contact” refers to an object abutting or touching another object. For example, a pen is in contiguous contact with a piece of paper when the pen is touching the paper.
As used herein, the phrase “retard member” refers to an article that impedes movement of the substrates in the direction of advancement.
As used herein, the phrase “face-to-face contact” refers to contact between adjacent faces of two substrates.
As used herein the phrase “guide baffle” refers to a device configured to guide a substrate along a path.
As shown in the example in
The topmost substrate 30, which is also referred to as a first substrate, has a lead edge 36 and a trail edge 38. As the topmost substrate 30 contacts the guide baffle 20, the lead edge 36 of the topmost substrate 30 advances in the direction 34 of advancement and the topmost substrate 30 is guided to the feed roll 14. The guide baffle 20 is operatively connected to a substrate stack 18 and is fixed between the feed roll 14 and the active retard roll 16.
The feed roll 14 has a high friction surface 40 and the active retard roll 16 has a high friction surface 42 that forms a nip 44 in the path of the topmost substrate 30. The feed roll 14 rotates in the direction 46 of advancement and the active retard roll 16 rotates in the direction 48 opposite of advancement. The orientation of the feed roll 14 and the active retard roll 16 is preferably set to align the roll center lines approximately perpendicular to the guide baffle 20, with the feed roll rotating about a first axis 33 and the guide baffle 20 being oriented to be generally perpendicular to a reference axis R that intersects the nip 44 and the first axis 33.
The guide baffle 20 provides an angular change in direction, represented by angle α, for the topmost substrate 30 as the topmost substrate 30 advances from the substrate stack 18 to the feed roll 14. The angle α is defined between a plane P coinciding with the top of the substrate stack 18 in an initial position and the guide baffle 20. As explained below, the substrate stack 18 may be angularly adjusted. The angle α is taken from the initial position of the substrate stack 18. The angle α between the guide baffle 20 and the substrate stack 18 may range from about 10 degrees to about 70 degrees, more specifically the angle α may range from about 30 degrees and about 40 degrees, and in particular the angle α may be about 35 degrees.
Due to the angular change provided by the guide baffle 20, during advancement of the topmost substrate 30, portions of the topmost substrate 30 are spaced from the guide baffle 20. The spaced portions of the topmost substrate 30 sag towards the guide baffle 20, providing the topmost substrate 30 with a concave profile 31. As described below, the concave profile 31 reduces the frictional contact between the substrates and enhances the ability to advance the topmost substrate 30 while allowing for separation of the second substrate 32. The guide baffle 20 preferably passes through the plane P so that the topmost substrate 30, and subsequent substrates, during advancement intersect the guide baffle 20 at a location spaced from end 39 of the guide baffle 20. With the guide baffle 20 passing through the plane P, the end 39 is located below the plane P. This configuration additionally facilitates the formation of the concave profile 31.
The apparatus 10 is configured to allow the nudger roll 12 to advance the topmost substrate 30 in the direction 34 of advancement until the lead edge 36 of the topmost substrate 30 enters the nip 44. As shown in
As the topmost substrate 30 advances in the direction 34 of advancement, the active retard roll 16 advances the adjacent second substrate 32 in the direction 35 opposite of advancement, separating from the topmost substrate 30 and forming a separation point 50 between the topmost substrate 30 and the adjacent second substrate 32. The concave curved profile 31 created by the guide baffle 20 and the opposing motion of the topmost substrate 30 and the adjacent second substrate 32 caused by the feed roll 14 and active retard roll 16 acts against the face-to-face contact forces, enabling the topmost substrate 30 and the adjacent second substrate 32 to progressively peel apart by pushing the second substrate 32 towards the baffle 20, while the first substrate 30 is being lifted opposite to the baffle 20. Since the nudger roll 12 is in the second position 28, this peeling separation point 50 between the topmost substrate 30 and the adjacent second substrate advances, without obstruction, from near the lead edge 36 towards the trail edge 38.
The substrate stack 18 may be advanced vertically to continuously feed substrates. Alternatively, the substrate stack 18 may be pivotally adjusted to raise the leading edges of the substrates in further feeding substrates. For example, with reference to
The elevator plate 62 maintains the substrate stack 18 at a constant vertical distance relative to the nip 44 formed by the feed roll 14 and the retard roll 16. The vertical position of the substrate stack 18 relative to the nip 44 is typically measured with a sensor (not shown) that monitors the position of the nudger roll 12 in the first position 26 and tracks the topmost substrate 30 as substrates are fed from the substrate stack 18. When the first position 26 of the nudger roll 12 drops below a predetermined height relative to the nip 44, the lifting apparatus 64 for the elevator plate 62 is enabled to raise the lead edge 68 of the elevator plate 62 and the substrate stack 18.
As substrates are removed from the substrate stack 18, an angle of inclination δ between the elevator plate 62 and the substrate tray 60 increases. The increased angle of inclination δ of the substrate stack 18 changes the trajectory of the lead edge of the topmost substrate 30 of the substrate stack 18 to be directed increasingly above the nip 44. To obtaining the concave profile 31 of the topmost substrate 30 the substrate feeder 10 must be configured such that angle β, representing the difference between the plane P, which coincides with the initial position of the top of the substrate stack 18, and the current position of the top of the substrate stack 18, remains less than angle α (angle α being constant). Thus, when the apparatus 10 includes an elevator plate 62 that changes the slope of the substrate stack 18, angle α is preferably selected such that angle α remains greater than angle β.
While the above description and
It will be appreciated that various of the above-disclosed and other features and functions, or alternative thereof, may be desirably combined into many other different systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims. In addition, the claims can encompass embodiments in hardware, software, or a combination thereof.
