Stock material or miscellaneous articles – Hollow or container type article – Polymer or resin containing
Reexamination Certificate
1999-02-24
2001-05-08
Morris, Terrel (Department: 1771)
Stock material or miscellaneous articles
Hollow or container type article
Polymer or resin containing
C428S036100, C428S036200, C428S035200, C355S117000, C442S097000, C442S101000, C442S110000, C442S131000, C474S268000
Reexamination Certificate
active
06228448
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is directed to an endless belt and method of making it for use in digital imaging systems, and more particularly, to such a seamless, reinforced belt which may be used in intermediate image transfer, toner fusing or transfusing, and/or sheet transport operations.
Digital imaging systems are widely used in the field of xerography and electrography where dry or liquid toner is used to print text and graphic images. For example, systems which use digitally addressable writing heads to form latent images include laser, light-emitting diode, and electron beam printers. Copiers use optical means to form latent images. Regardless of how they are formed, the latent images are inked (or toned), transferred and fixed to a paper or polymer substrate. Such systems typically include a component such as an endless belt, roll or drum which is utilized for latent image recording, intermediate image transfer (transfer of a toner image to the belt followed by transfer to a substrate), transfusing of toner (transport of the unfused image onto the belt with subsequent fusing), contact fusing, or electrostatic and/or frictional transport of imaging substrates such as paper, transparencies, etc.
In the case of endless belts, such belts are typically moved or driven under appropriate traction and tension by rotating cylindrical rollers. As such belts play a critical role in the imaging or substrate transport process, they must be engineered to meet exacting standards. For example, image transfer belts must be seamless, flexible, and must exhibit uniform flatness. Further, the belts should provide certain electrical properties (dielectric constant, volume and surface resistivity, etc.) chemical properties (resistance to humidity, UV light, etc.) and dimensional specifications (circumference, thickness, width, etc.) which may vary depending on the desired application.
If the belts include nonuniformities as manufactured or in operation, various problems arise. For example, where the belts are used for latent image recording, surface flatness is of critical importance as the surface of the belt may be electrostatically charged using high resolution laser beams positioned over the belt. If the belt is not uniformly flat, image quality may suffer due to randomly localized deformation.
Accordingly, there is still a need in the art for an endless belt for use in digital imaging systems which can be manufactured and operated to be within exacting tolerances, including surface flatness, and which may be used for a wide variety of imaging, image transfer or sheet transport operations.
SUMMARY OF THE INVENTION
The present invention meets that need by providing an endless belt having precise and uniform flatness which also possesses a working surface which can be tailored to provide the proper characteristics for image transfer or sheet transport.
In accordance with one aspect of the present invention, an endless belt for use in a digital imaging system is provided which has first and second edges and a plurality of plies. By uniform flatness, it is meant that the thickness of the belt varies less than 0.001 inches (0.003 cm) from the first edge to the second edge and also from one circumferential point (location) to another. The circumferential uniformity of the belt also varies less than 0.005 inches (0.013 cm) circumferentially in conicity to provide circumferential uniformity over the entire belt structure.
The belt includes an elastomeric base ply and an elastomer-impregnated spun cord layer on the base ply. By “cord”, we mean either a single fiber or multiple fibers formed into a continuous cord. By “impregnated”, we mean that the elastomer at least partially occupies spaces between the spun fiber or fibers but does not necessarily impregnate individual fibers.
The belt further comprises a woven or non-woven fabric ply on the cord layer, and an outer elastomeric ply on the fabric ply which has a working surface. The fabric ply may also be impregnated with an elastomer. It should be understood that for purposes of the present invention, the term “on” when referring to the position of the plies means that one ply is adjacent to and in contact with the ply that it is “on”. Further, it should be understood that for purposes of the present invention, the terms “ply” and “layer” are interchangeable.
The outer elastomeric ply functions as a working surface layer which is adapted to accept an imaging composition or to transport a substrate. For example, the surface layer may be used as an intermediate image transfer surface which accepts a toned and unfused image from an image recording component; as a dielectric surface which accepts electrostatic surface charge density for attracting, holding in register, and transporting paper or transparency substrates; or as a toner fusing surface which can press and fix (or fuse) toner to a substrate.
The elastomeric base ply and outer ply are preferably selected from the group consisting of silicone, fluorosilicone, fluorocarbon, EPDM (ethylene-propylene diene terpolymers), EPM (ethylene-propylene copolymers), polyurethane elastomers, and blends thereof. The elastomer used to impregnate the spun-cord and fabric layers may also comprise the above elastomers.
In one embodiment of the invention, the outer elastomeric ply is electrically conductive. By electrically conductive, it is meant that the outer elastomeric ply preferably has a surface resistivity of less than about 10
14
ohm/square which is desirable for intermediate image transfer, toner fusing or transfusing applications.
In applications such as substrate transport in which a surface charge density is applied to the working surface layer, the outer elastomeric ply or entire endless belt preferably has a volume resistivity of greater than about 10
12
ohm •cm.
The method of making the endless belt generally comprises the steps of applying an uncured elastomer to a workpiece such as a mandrel to form a base layer. The elastomer is preferably coated onto the surface of the workpiece in the form of a solvated rubber or cement. Next, the workpiece is rotated to wind an elastomer-impregnated cord circumferentially around the base layer, and a woven or non-woven fabric layer is applied over the cord layer. Preferably, the wound cord layer is coated with additional elastomer prior to application of the fabric layer. An uncured elastomer layer is then applied over the fabric layer to form an outer layer. The outer elastomer layer may be applied by coating it in the form of a solvated rubber or it may be applied in the form of a calendered formable sheet.
After the outer elastomeric layer is applied, the assembled layers are then cured. After curing, the surface of the outer elastomeric layer is preferably ground or otherwise treated to achieve uniform flatness such that the elastomeric layer functions as a working surface layer as described above.
Endless belts formed by the methods of the present invention have been found to exhibit excellent performance when installed under tension in digital imaging machines. Based on the construction and choice of elastomer, the belts have also been found to exhibit adequate toner acceptance properties for use in intermediate image transfer, adequate retention of surface charge density for substrate transport applications, or good toner release properties for fusing or transfusing applications.
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Brooks Ray
Ferguson Thomas Gerald
Haddock William Haul
McLean Michael E.
Ndebi Sylvain L.
Day International Inc.
Killworth, Gottman Hagan & Schaeff, L.L.P.
Morris Terrel
Singh Arti R.
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