PAPER GUIDES FOR CONTINUOUS FEED PRINTING

Abstract

A system for providing damage-free travel of media on media path in an image-forming apparatus is described. The system includes a roller configured to transport media on the media path and one or more guides positioned at either end of the roller. Each guide includes an inner end extending into the media path, and an outer end extending beyond the media path, the outer end having a height greater than the height of the inner end. Moreover, the surface between the inner end and the outer end is concave in shape.

Description

TECHNICAL FIELD

The presently disclosed embodiments generally relate to continuous feed printing environments, and more particularly, to media handling during printing processes.

BACKGROUND

A continuous feed (CF) printer, as opposed to cut sheet printers, prints on a band/roll of paper and not on discrete separate sheets. The roll of paper is separated into single sheets after printing is complete. CF printing systems are used in many industries, such as banks, insurance companies, and print shops for printing items such as forms and checks. These systems generally provide high-speed production print jobs with fewer registration errors than cut sheet printing systems during duplex printing.

Typically, CF printing systems require significant transportation of paper along the media paths. For example, during duplex printing, two CF printers print on the same continuous sheet of paper; the second printer receives paper from the first printer and prints on the unprinted side. A single paper path links the two printers. Generally, in multiplex printing, several printers are part of the same paper path.

The term “paper path” is used in the art to refer both to the route followed by media through an imaging system and to equipment employed for handling the media on that route. In a continuous feed system, the paper path includes equipment such as shafts, rollers, and diverting mechanisms, all used for transporting paper through the system.

With paper moving rapidly through a continuous feed system, maintaining the paper exactly positioned on the paper path assumes significant importance. Anisotropy of the paper, however, can cause the paper to drift out of position. Environmental conditions, such as humidity and temperature, can cause the paper to stretch or otherwise change shape, resulting in the paper drifting from the desired location on the paper path. Conventionally, guides are attached to rollers to provide appropriate paper alignment. Rings located at the ends of shafts or rollers are designed to prevent side-to-side movement.

That solution may not function properly for many media, however. Lightweight media, under about 60 gsm, suffer from damage caused by the ring-shaped guides. Some systems have employed electronic sensors to actuate a roller to compensate skew. This solution is, however, expensive.

It would be highly desirable to have a simple and cost-effective guide that prevents media damage and printing errors for lightweight media sheets.

SUMMARY

The present disclosure describes a system for promoting damage-free travel of media on a media path in an image-forming apparatus. The system includes a roller configured to transport media on the media path and one or more guides positioned at either end of the roller. The guides extend in a direction transverse to the media path. Each guide includes an inner end extending into the media path, and an outer end extending beyond the media path, the outer end having a height greater than the height of the inner end. Moreover, the surface between the inner end and the outer end is concave in shape.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an exemplary embodiment of a media path in a continuous feed printing system.

FIG. 2 illustrates an exemplary embodiment of a guided media system for transporting damage free media using a media guide.

FIG. 3 illustrates the sectional view of the guided media system discussed in FIG. 2.

FIGS. 4 and 5 illustrates another exemplary sectional view of the media guide depicted in FIG. 2.

DETAILED DESCRIPTION

The following detailed description is made with reference to the figures. Preferred embodiments are described to illustrate the disclosure, not to limit its scope, which is defined by the claims. Those of ordinary skill in the art will recognize a number of equivalent variations in the description that follows.

Overview

The present disclosure describes various embodiments of a system providing damage-free control of media on a media path in an image-forming apparatus, such as a continuous feed printer. The media path includes equipment such as rollers for transporting media sheets. One or more media guides positioned at either end of the rollers facilitate appropriate alignment of the media over the rollers. The guides extend in a direction transverse to the media path having an inner end extending into the media path rollers and an outer end extending outwards. The height of the outer end is greater than the inner end, and the surface between these two ends describes a concave parabola. These guides prevent edge damage by auto-positioning media onto the rollers. Moreover, this guide accommodates media of variable weight, especially lightweight media otherwise susceptible to edge damage.

For purposes of description, the present disclosure is discussed in relation to continuous feed printing systems; those skilled in the art, however, will appreciate that the subject matter disclosed may be applicable to any image-forming device that may face media edge damaging issues. The term “media” used in the present disclosure refers to continuously fed media of paper, plastic, or other suitable material. Moreover, the terms “media”, “media sheet”, “sheet”, and “paper” are interchangeable as used below.

Exemplary Embodiments

FIG. 1 shows a typical media path 100 for transporting media in a conventional printing system. For purposes of description, consider the media path 100 as part of a conventional duplex printing system that includes two parallel simplex continuous feed printers 102 and 104 that print on either side of a sheet 106. As known to those in the art, one CF printer accepts media that comes from the other and prints on its unprinted side, providing duplex printing. As shown, the media output from the CF printer 104 having print job on one side of the sheet 106 is diverted to the CF printer 102. The media path 100 between the two CF printers 102 and 104 includes rollers 108 or other known devices that assist in transportation process. Those skilled in the art will comprehend that such a media path may be present in any printing device that requires continuous sheet of paper to traverse form one device to another.

In general, the sheet 106 traveling along the media path 100 is required to be under tension using known devices such as brakes. Such paper sheets traveling under tension may experience misalignments that generate printing errors. Misalignment may arise due to imperfections in media path equipment, such as manufacturing flaws, inappropriate adjustment of the media path equipment. For example, improper parallelism of the rollers 108 may divert the media from the desired path towards left or right.

Consequently, the media path 100 includes conventional guides 110 that ensure appropriate alignment of the sheet 106 over the rollers 108. The guides 110 are employed to compensate for the imperfections in media path equipment. The guides 110 are ring-shaped structures that present a flat vertical surface to the edges of the sheet 106. As already discussed, the substantially vertical surface of the guides 110 may damage media having lighter weight.

FIG. 2 and FIG. 3 depict a guided media system 200 illustrating an arrangement that provides damage-free media travel. FIG. 2 includes rollers 202 to transport a sheet 204 along a direction referred to as media path, depicted by an arrow 206, such as the media path 100. The section of the media path depicted here includes two rollers 202 for transporting lightweight media. To prevent edge damage and enable appropriate alignment of the sheet 204, the system 200 employs guides 208 positioned at either end of the rollers 202, extending in a direction transverse to the media path. The guided system 200 employs the curved guides 208 along the media path 100 instead of the roller-shaped guides 110 employed in FIG. 1. As shown, the longitudinal axis of the guides 208 may be substantially parallel to the longitudinal axis of the rollers 202.

The guides 208 may be positioned by any convenient means that enable lateral displacement of the guides 208 along the longitudinal axis of the rollers 202 in order to accommodate media having variable width. Moreover, the guides 208 are positioned such that a portion of the media sheet 204 passes over the guides 208. The cross-sectional views of the guide 208 in the 4-4′ and 5-5′ plane are discussed in the following sections in connection with FIGS. 4 and 5.

FIG. 3 depicts a cross-sectional view of the guides 208 in the 3-3′ plane. As shown, the guides 208 include an inner end 216 that extends towards the media path and an outer end 218 extending out. The height of the inner end 216 is lower than that of the outer end 218, and the surface between these two ends describes a substantially concave parabola. As shown, the height of the inner end 216 is substantially negligible to avoid any damage to the media sheet 204. In one implementation, the surface of the guide 208 may be elliptical, or Gaussian in shape. The curvature of the guide may be determined based on characteristics of the media, such as its Young's modulus, the thickness, and the characteristics of the system, such as the tension in the media path, and the paper path configuration. The surface is concave, and the radius of the curvature may be 5 inches, for example. In another implementation, the height of the outer end may be 1 inch greater than the inner end. The guides 208 may be manufactured from a metallic material such as Aluminium or Stainless Steel, which may be easily available and subsequently, promotes economy.

While traversing on the media path, typically the center of the media sheet 204 aligns with the center of the gap between the two guides 208, and it should be understood that the media edges traverses a greater path length than the center of the sheet 204. As shown, the guides 208 are positioned on the rollers 202 such that the distance between the two guides is approximately equal to the width of the media traversing over the rollers 202. A skew, however, may dislocate the media sheet 204 towards the left or right. This dislocation results in advancing the sheet over the corresponding guide 208, and subsequently, increases the path length in the region of the skew. The length extension increases the tension on the side of the sheet 204 towards the skewing direction, and the media sheet 204 tends to move in the opposite direction due to the elastic characteristics. The difference in the path length pushes the media sheet 204 to the lowest energy position, which is the center of the gap between the guides 208.

Further, the advancement of the media sheet 204 over the curved surface of the guides 208 does not damage the media edges, as the parabolic shape presents a smooth surface to the media edges. These parabolic-shaped guides 208 accomplish damage-free transport of any media sheet weighting from 200 gsm to 40 gsm. It should be understood that the concepts set out here could be employed both in devices handling lightweight media, such as paper sheets, as well as transport systems handling heavyweight sheets, such as corrugated cardboard.

FIG. 4 and FIG. 5 depict sectional views of the guide 208 in the plane 4-4′ and 5-5′, respectively. FIG. 4 depicts the upper surface of the guide 208 in close proximity to the outer end 218. As clearly shown, the guide 208 outlines a convex upper surface 220. Further, each guide 208 includes two openings 222 positioned and dimensioned to slidably receive the rollers 202. FIG. 5 illustrates the sectional view of the guide 208 in close proximity to the inner end 216. Due to the parabolic shape of the guides 208, the upper surface 224 is substantially flat. Moreover, the height of the guide 208 in FIG. 4 is greater than that in FIG. 5.

It should be noted that the description below does not set out specific details of manufacture or design of the various components. Those of skill in the art are familiar with such details, and unless departures from those techniques are set out, techniques, designs and materials known in the art should be employed. Those in the art are capable of choosing suitable manufacturing and design details.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. It will be appreciated that several of the above-disclosed and other features and functions, or alternatives 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.

Claims

1. A system for promoting damage-free travel of media on media path in an image-forming apparatus, the system comprising:

a roller configured to transport media on the media path; and

one or more guides positioned at either end of the roller and extending in a direction transverse to the media path, each guide having: an inner end extending into the media path; and an outer end extending beyond the media path, the outer end having a height greater than the height of the inner end; and a substantially concave guide surface between the inner end and the outer end.

2. The system of claim 1, wherein the guide surface is substantially parabolic.

3. The system of claim 1, wherein the curvature of the guide surface is determined based on:

young's modulus of the media;

thickness of the media;

tension in the media path; or

configuration of the paper path.

4. The system of claim 1, wherein each guide is positioned at either end of the roller such that the longitudinal axis of the guide is substantially parallel to the longitudinal axis of the roller.

5. The system of claim 1, wherein the guides are positioned at both the ends of the roller.

6. The system of claim 1, wherein the guides are laterally displaceable on the roller to accommodate media of variable width.

7. The system of claim 5, wherein the guides are positioned at the two ends of the roller such that the distance between the two guides is approximately equal to the width of the media traversing over the roller.

8. The system of claim 1, wherein the guides are manufactured from a metallic material.

9. A guide for promoting damage-free travel of media on media path, the guide comprising:

an inner end displaceably positioned at either end of a roller, the inner end extending into the media path;

an outer end extending outwards from the media path, the outer end having a height greater than the height of the inner end; and

a substantially parabolic guide surface between the inner end and the outer end, the parabolic surface prevents lateral displacement of the media on the media path.

10. The guide of claim 9, wherein the guide is positioned at both the ends of the roller.

11. The guide of claim 9, wherein media traverses over the roller such that a portion of the media passes over the curved guides.

12. The guide of claim 10, wherein the guides are positioned at the either end of the roller such that the distance between the two guides is approximately equal to the width of the media traversing over the roller.

13. The guide of claim 9, wherein the guides are laterally displaceable on the roller to accommodate variable width media.

14. The guide of claim 9, wherein the parabolic surface of the guide directs media towards the center of roller.

15. The guides of claim 9, wherein the parabolic curve of the guides is determined based on:

young's modulus of the media;

thickness of the media;

tension in the media path;

configuration of the paper path.