Sheet feeding or delivering – Delivering – Rotary conveyor
Reexamination Certificate
1999-11-05
2001-06-05
Skaggs, H. Grant (Department: 3651)
Sheet feeding or delivering
Delivering
Rotary conveyor
C271S264000, C271S272000
Reexamination Certificate
active
06241245
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to improved sheet feeding, with particular utility for document feeders or transports for sequentially feeding original document sheets. The invention serves to reduce the imparting to the sheet material being transported and handled of friction, static charge, and foreign deleterious material while substantially minimizing the burnishing of the surface of the sheet material being transported.
2. Description of the Prior Art
As xerographic and other copiers and other document handlers in general increase in speed and become more automatic in their operation, it is increasingly important to provide higher speed yet more reliable and more automatic handling of the resulting copies, in sheet material form, while at the same time maintaining the visual quality of those resulting copies.
Throughout this disclosure the term sheet is intended to refer both to individual sheets as well as to continuous web-fed media.
Standard paper guide design relies on a series of parallel in-line ribs to decrease overall friction on the sheet as it passes through the paper path. This method also ensures that a minimum of static, dirt, and moisture is transmitted from the baffle to the sheet. In most instances, these ribs are parallel to the direction of the sheet transporting path to which the sheets are confined. A patented example of a modified design in which the ribs are in a diagonal relationship with respect to the sheet feeding path is provided in commonly assigned U.S. Pat. No. 5,000,438 issued on Mar. 19, 1991 to Sardano et al. In this patented instance, apparatus is disclosed for feeding flimsy sheets of paper or the like, preferably dog-eared or curled edge original documents. To guide and flatten the non-planar edges of the sheets, the sheet feeding guide surface of the apparatus has a plurality of spaced apart and slightly vertically extending sheet-engaging ribs. These ribs are divided into two opposingly diagonal sets of plural ribs on the respective sides of the sheet feeding path, extending diagonally away from one another from the centerline of the sheet separator or feeder towards the respective outer edges of their respective side of the sheet feeding path. These diagonal ribs may have their upper surfaces in a common plane but can iron out towards their respective path sides the curled or folded corners of the sheet in that side of the path.
While this technique of using raised ribs is acceptable for most requirements, an undesirable outcome of parallel rib design is high paper surface element dwell time on a concentrated area of the rib/sheet interface. This situation may result in paper marking and rib surface wear. Paper marking becomes a larger issue with some document handling equipment when there is a requirement to accommodate coated stock papers or transparency material which are more sensitive to surface impressions caused by surface element dwell time and high concentration of pressure between the rib and sheet interface.
It was with knowledge of the foregoing state of the technology that the present invention has been conceived and is now reduced to practice.
SUMMARY OF THE INVENTION
The present invention relates to apparatus for transporting sheets in a longitudinal direction and includes an improvement for reducing the imparting to the sheet material of friction, static charge, and foreign deleterious material while substantially minimizing the burnishing of the surface of the sheets. To this end, a plurality of elongated sheet supporting rib members project outwardly from a guide surface, extend diagonally relative to the longitudinal direction. They may be all of uniform height above the sheet guide surface and be of uniform cross section although such uniform dimensioning is not necessary for the invention. The sheet supporting rib members are so dimensioned and positioned that any random element of a sheet being fed in the longitudinal direction through the apparatus crosses only one of the sheet supporting rib members. Actually, a plurality of first sheet supporting rib members extend diagonally in a first direction and another plurality of elongated second sheet supporting rib members extend diagonally in a second direction which is transverse of the first direction. The incidence angle between the longitudinal direction and each of the sheet supporting rib members is in the range of about 5° to about 30° and, preferably, in the range of about 10° to about 20°. A drive roll mechanism may be provided for engaging the sheets in the region of the sheet supporting rib members for transporting the sheets in the longitudinal direction. However, other mechanisms for advancing the sheets may be provided at other locations.
The technique herein disclosed seeks to provide a method to use angled sheet supporting rib members in a paper handling device to enable low rib to sheet surface pressures. The technique minimizes the marking of the sheet surface as it passes through the paper handling mechanism by decreasing the dwell time and the pressure of the sheet surface on the angled supporting rib members.
Throughout this disclosure, the term “burnish” will be intended to refer to a particular resulting optical effect which may occur for substrates such as sheets in the form of treated paper stock and transparencies which may be acrylic sheets. Coated paper stock has a “nap” which may be “laid down” when engaged, as by a sheet supporting rib member, visually affecting the optical quality of the sheet. In a similar fashion, such engagement of an acrylic sheet, or transparency, may affect its diffraction, being different at the locations of sheet supporting rib member engagement by a sheet supporting rib member than at all of the other locations on the sheet. Such burnishing can be particularly noticeable when images on the transparency are projected onto a screen and thereby magnified.
The arrangement of the sheet supporting rib members mitigate high sheet-to-rib surface pressures and dwell times by placing the rib members at an angle to the paper path sheet movement direction. The sheet supporting rib members are angled from the approximate center of the paper path, expanding toward the front and back edges of the paper path structure. This arrangement ensures that lateral forces applied to the sheet will have the positive effect of imparting a small lateral force from the center to the outside edges of the sheet to enable prevention of paper wrinkle. This method of rib arrangement has been found to be most effective on surface sensitive substrates with low frictional coefficients.
A primary feature, then, of the present invention is the provision of an improved technique for sheet handling by a document feeder or handler to reduce the imparting to the sheet material being fed and handled of friction, static charge, and foreign deleterious material while substantially minimizing the burnishing of the surface of the sheet material.
Another feature of the present invention is the provision of sheet handling apparatus in which a plurality of elongated sheet supporting rib members project outwardly from the guide surface, the sheet supporting rib members extending diagonally relative to the longitudinal direction, the sheet supporting rib members being so dimensioned and positioned that any random element of a sheet being fed in the longitudinal direction through the apparatus crosses only one of the sheet supporting rib members.
Still another feature of the present invention is the provision of such a technique according to which a plurality of elongated first sheet supporting rib members extend diagonally in a first direction and a plurality of elongated second sheet supporting rib members extend diagonally in a second direction which is transverse of the first direction.
Yet another feature of the present invention is the provision of such a technique according to which the incidence angle between the longitudinal direction and each of the sheet supporting rib members is in the ra
Hollar Thomas C.
Powley Wayne C.
Perman & Green LLP
Skaggs H. Grant
Xerox Corporation
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