Document transport for accurate printing

Information

  • Patent Grant
  • 6595517
  • Patent Number
    6,595,517
  • Date Filed
    Tuesday, August 7, 2001
    23 years ago
  • Date Issued
    Tuesday, July 22, 2003
    21 years ago
Abstract
A document transport for moving documents past a document processing station utilizes a drive roller having a mass sufficient to provide a flywheel effect to stabilize speed of documents passing between the drive roller and a pinch belt in contact with a portion of the circumference of the drive wheel. The drive wheel may additionally have a circumference large enough to prevent document slippage between the drive wheel and the pinch belt.
Description




FIELD OF THE INVENTION




The present invention relates to document processing equipment, and more particularly to a document transport apparatus at a document processing station for providing accurate processing.




BACKGROUND OF THE INVENTION




Printing on documents using non-fully-formed devices requires accurate knowledge of the motion of the document in order to place dots or spray lines on the document with sufficient accuracy for machine reading. Typically, motors and synchronous belts are used to impart motion to document drive rollers. These motors and belts have cogging forces which can sometimes cause short term speed fluctuations. Because characters or symbols to be printed are typically small (about ⅛ inch or smaller), such short term speed fluctuations can cause inaccurate character placement. This inaccurate placement of the ink on the document makes the character or symbol impossible to machine read.




Printer accuracy can be improved by reducing the cogging forces of the drive rollers. Conventional systems attempt to reduce the cogging forces by providing extremely high precision motors and motion transmission devices which are expensive. Other systems use flywheels to minimize short term speed fluctuations caused by cogging or other pulsing type forces.




In addition, many other types of document transports allow approximately 0.1 inch of document movement perpendicular to the transport direction. As such, conventional document transport systems used in conjunction with non-fully-formed character printers may allow the document to slip with respect to drive rollers because they do not enable a firm grip. Speed regulation is inadequate unless extra flywheels are added, which add to the space issues, cost issues and complexity of the document transport.




In general, a flywheel is a device for storing energy or momentum in a rotating mass. Flywheels are usually a heavy wheel which may be any shape, such as disk or saucer, and are typically symmetric. Flywheels are used for a variety of purposes. One commonly known mechanical purpose of flywheels is to moderate speed variations in an engine. The flywheel uses its inertia to even out quick power outbursts by a power supply or sudden loads on a system.




SUMMARY OF THE INVENTION




As such, it is desirable to provide a document transport for providing speed regulation for documents that are to have characters or other machine readable symbols printed on them by non-fully-formed character or symbol printing devices, such as ink-jet printers, or thermal or impact dot matrix printers, and the like.




The present invention provides document drive rollers that are of relatively large moment of inertia to minimize speed fluctuations and are simultaneously arranged so as to enable a firm grip of the document while being printed.




Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.











BRIEF DESCRIPTION OF THE DRAWINGS




The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:





FIG. 1

is a plan view of a preferred embodiment of a document transport apparatus taken from above a base plate and arranged according to the principles of the present invention;





FIG. 1A

is a perspective view of the embodiment of

FIG. 1

;





FIG. 2

is a cross-sectional side view of a preferred embodiment of the document transport apparatus of

FIG. 1

; and





FIG. 3

is a cross-sectional side view of another preferred embodiment of the document transport apparatus of FIG.


1


.











DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS




The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.




It will be understood that the invention may be adapted for use with check reader/sorter/amount encoder/sorters, batch ticket printers, check amount encoders, check printers, security document printers, deposit envelope, deposit slip printers for ATMs and the like.





FIGS. 1 and 1A

illustrates a document transport


100


having a primary document transport apparatus arranged according to the principles of the present invention. The document transport apparatus includes components that are commonly placed above or on one side of a plane known as a baseplate


150


(FIG.


1


A). The document drive components typically have shafts rigidly connected to them which protrude through and below the baseplate


150


. These shafts are allowed to rotate in bearing systems typically mounted to the baseplate. At the bottom end of these shafts, pulleys, belts and/or motors are connected to provide rotational motion to the document drive components. The document drive components are most commonly employed with document drive rollers. For clarity the “below baseplate” components are not shown, but these components are well known to those practiced in the arts of transporting documents.

FIG. 1

presents apparatus of a preferred embodiment as seen from a view taken normal to baseplate


150


of FIG.


1


A.




Documents, such as


102


of

FIG. 1

, may enter the document transport from a variety of upstream devices


101


, such as document feeders, other transports that endorse checks, etc. They may be inadequately aligned to accurately print at precise locations on the document with respect to a registration edge. For this reason, aligner disks, such as


104




a, b, c


, may be used for the pinch rollers for the first few drive rollers


106




a, b, c


in the document transport. Such aligning disks are well known to those practiced in the arts of transporting documents.




After alignment, the documents


102


enter the pinch or grip between the large drive roller


106




b


and the pinch belt


108


. The pinch belt


108


wraps around a substantial portion of the circumference of the large diameter roller


110


. The pinch belt


108


is driven by the large diameter roller


110


. This belt


108


in turn drives the document


102


just before and just after the large diameter drive roller


110


. Belt


108


also drives an idler


112


which enables the bolt


108


to be of continuous construction. This idler


112


is spring loaded to provide tension in the belt. The belt tension provides substantial pinch force between the belt


108


and the large diameter drive roller


110


.




Drive roller


110


is large enough so that length of grip between the tangent point of the belt/large roller and the print head


114


is a substantial portion of the length of the documents being processed to provide a substantial grip of the document just before printing commences and throughout printing on the beginning portion of the document, thereby preventing document slippage between the large drive roller


110


and the pinch belt


108


. Drive roller


110


is additionally made large enough to provide requisite mass for flywheel effect (in a check processing application, on the order of 10 inches in diameter) to stabilize documents, such as checks, at reading stations.




Similarly, after printing stops, possibly near the end of the document, there is an equally large length of grip between the print head


114


and the tangent point of the belt/large roller to provide a substantial grip of the document throughout document processing, such as printing, on the remaining portion of the document, thereby preventing document slippage between the large drive roller


110


and the pinch belt


108


. Additionally, the surface of drive wheel


110


preferably utilizes a friction material which provides further document slippage prevention.




Document


102


is initially discharged from the processing station by the right-hand portion


108




a


of pinch belt


108


in conjunction with pinch roller


120


and idler


115


.




After exiting the pinch belt


108


, the document


102


is under control of the last two drive rollers


116


and


118


. These drive rollers


116


and


118


have associated therewith typical pinch rollers


122


and


124


, which are well known to those practiced in the art of transporting documents. The document


102


is delivered to a downstream device


126


, such as microfilms, digital imagers, stackers, etc.





FIG. 2

is a view of a section in

FIG. 1

passing through the large drive roller center axis of rotation


111


and the print head


114


. Some types of print heads, such as certain inkjet print heads, may require space behind the document for sensors. These sensors detect jets of ink for adequacy when the document is not present.

FIG. 2

illustrates space


200


behind the document


102


if such sensors are necessary.





FIG. 3

illustrates a modification to the large diameter roller


110


to accommodate printing processes that require substantial force be applied to the document, such as for dot matrix impact printer applications, for example. The bottom edge


110




a


of the large drive roller is lowered to provide a massive and rigid back-up of the document opposite the print head.




Also, because the pinch belt


108


wraps the document


102


around the curvature of the large drive roller


110


, the document


102


is stiffened in the direction of the print head


114


. Other types of document transports allow approximately 0.1 inch of document movement perpendicular to the transport direction. In this invention, the wrap and the stiffening eliminate this perpendicular movement, providing a more consistently precise distance between the document and print head. This results in more accurate printing.




The symmetrical arrangement of all the drive rollers


106




a


,


106




b


,


116


,


118


and pinch belt


108


serves to provide the property that a document leave the transport in the same direction and at the same elevation as it entered the transport. This enables the transport to be inserted in existing document processing equipment without major modification to the existing equipment.




The large diameter drive roller


110


further provides an efficient way to obtain a large moment of inertia. A large moment of inertia provides a flywheel effect, which makes the document move smoothly and with good speed regulation through the printing area. It is commonly known from principles of engineering mechanics that the moment of inertia is proportional to the fourth power of the flywheel diameter for an homogeneous cylinder and proportional to the first power of the flywheel cylinder's material density. Therefore, it is more efficient to use a large diameter as well as a high material density for the drive roller


110


.




Gripping the document against the large moment of inertia, large drive roller gives the best short term speed regulation to the document.




Additionally, the drive rollers


106




a


,


106




b


,


116


,


118


on either side of the large drive roller


110


that have a somewhat smaller diameter, further serve to provide flywheel effect to the entire document transport, enhancing speed regulation. Additionally, they provide a smooth turning of the document towards and away from the large diameter drive roller.




The present invention preferably uses friction material as a drive roller surface plus increased surface to surface contact between drive roller and the document to minimize slippage.




The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.



Claims
  • 1. A document transport for moving documents past a document processing station, the document transport including:a drive roller adapted to be positioned adjacent the document processing station; a pinch belt wrapped around a portion of the circumference of the drive roller and driven by the drive roller; and, a drive belt idler for providing tension to the pinch belt, and adapted to be positioned adjacent the portion of the circumference of the drive roller around which the pinch belt is wrapped, wherein the drive roller has a mass sufficient to provide a flywheel effect to stabilize speed of documents passing between the drive roller and the pinch belt.
  • 2. The document transport of claim 1 wherein the drive roller has a circumference large enough to prevent document slippage between the drive roller and the pinch belt.
  • 3. The document transport of claim 1 wherein the portion of the circumference of the drive roller is on the order of 90°.
  • 4. The document transport of claim 1 wherein a diameter of the drive roller is on the order of at least 10 inches.
  • 5. The document transport of claim 1 further including:at least one input drive roller having an axis of rotation positioned at a first side of an axis of rotation of the drive roller and adapted for feeding documents between the pinch belt and the drive roller; and at least one output drive roller having an axis of rotation positioned at a second side of the axis of rotation of the drive roller and adapted for withdrawing documents from between the pinch belt and the drive roller.
  • 6. The document transport of claim 5 wherein the input and output drive rollers are symmetrically positioned at directly opposite sides of the axis of rotation of the drive roller.
  • 7. A document transport for moving documents past a document processing station, the document transport including:a first drive roller adapted to be positioned adjacent the document processing station; a pinch belt wrapped around a portion of a circumference of the fist drive roller and driven by the drive roller, and, a drive belt idler for providing tension to the pinch belt, and adapted to be positioned substantially adjacent the midpoint of the portion of the circumference of the first drive roller around which the pinch belt is wrapped, wherein the first drive roller has a circumference large enough to prevent document slippage between the first drive roller and the pinch belt.
  • 8. The document transport of claim 7 wherein the portion of the circumference of the first drive roller is on the order of 90°.
  • 9. The document transport of claim 7 wherein a diameter of the first drive roller is on the order of at least 10 inches.
  • 10. The document transport of claim 7 further including:at least one input drive roller having an axis of rotation positioned at a first side of an axis of rotation of the first drive roller and adapted for feeding documents between the pinch belt and the first drive roller; and at least one output drive roller having an axis of rotation positioned at a second side of the axis of rotation of the drive roller and adapted for withdrawing documents from between the pinch belt and the drive roller.
  • 11. The document transport of claim 10 wherein the at least one input drive roller and the at least one output drive roller are symmetrically positioned at opposite sides of the axis of rotation of the first drive roller.
  • 12. A document transport for moving documents on an edge thereof past a document processing station along a path defined by a surface of a baseplate, the document transport comprising;a primary drive roller mounted to the baseplate surface for rotation of a drive roller contact spice about an axis of rotation substantially normal to the baseplate surface, the contact surface positioned for presenting documents abutting the contact surface to a document processor, a pinch belt having a pinch belt contact surface in contact with a portion of the drive roller contact surface and adapted for applying pressure to documents passing along the drive belt contact surface facing the document processor, and, a spring-loaded drive belt idler for providing tension in the pinch belt the spring-loaded drive belt idler being mounted to the baseplate positioned substantially adjacent to a midpoint of the pinch belt contact surface, wherein the primary drive roller has a mass sufficient to provide a flywheel effect to stabilize speed of documents passing between the primary drive roller and the pinch belt.
  • 13. The document transport of claim 12 further comprising:at least two input drive rollers mounted to the baseplate surface at a first side of the primary drive roller for presenting documents thereto; and at least two output drive rollers mounted to the baseplate surface at a second side of the primary drive roller for extracting documents therefrom.
  • 14. The document transport of claim 13 wherein the input drive rollers and the output drive rollers are mounted to the base plate surface symmetrically with respect to the primary drive roller.
US Referenced Citations (4)
Number Name Date Kind
3941375 La White et al. Mar 1976 A
4659073 Leonard Apr 1987 A
5676368 Wilson et al. Oct 1997 A
5848784 Tranquilla Dec 1998 A