Patent Application
20110135348
This invention relates to an electrophotographic color system and more specifically to an intermediate transfer belt used in these systems.
In one electrophotographic color system, an array or series of different color imaging stations are aligned above an endless intermediate transfer belt (ITB). Each imaging station contains a raster output scanner (ROS), photoreceptor drum, development station, and cleaning station. The ROS emits an electronic beam (laser) which impinges on the rotating photoconductive drum, thereby causing that location on the drum to undergo a change in electrical charge. As the drum continues to rotate past the development station, toner particles of a color which is unique to that imaging station will attach to the drum at the location charged by the ROS. This colored image is then transferred from the drum to an intermediate transfer belt (ITB) that is passing by, and in contact with, that photoreceptor drum. As the intermediate belt passes by the different imaging stations (each usually containing a different color) it picks up subsequent color layers from the drums to create a complete color image which is then transferred to media.
Systems using intermediate transfer belt (ITB) architectures in the lower cost markets have identified passive belt tracking as a low cost alternative to active steering. Where as actively steered systems require a closed-loop control system consisting of multiple sensors, motors, and various other hardware and software components, the passively steered systems work on mechanics alone. One method for passive steering is through the use of belt steering or guide ribs. These ribs are adhered to the belt's surface and provide a mating surface with notched rollers, or the like, within the belt module. This interface keeps the belt (ITB) aligned as it rotates, preventing lateral movement, and in turn, ensuring proper image-on-image and image-on-paper registration.
This invention provides a method and device for aiding in the application of one or more steering ribs to the inside circumference of an intermediate transfer belt. The device consists of a drum or cylinder onto which the self-adhesive ribbing material placed and held via vacuum. The ITB is then slid over the cylinder or drum and located with respect to the ribbing. At this point the vacuum is removed and a puff of air is applied, transferring the ribbing material to the transfer belt. The process would be repeated to apply a rib on the other end or other ITB location if desired. This cylindrical apparatus with vacuum and air apertures greatly simplifies application of the steering rib and improves quality and uniformity.
The sequence of operation of the method of this invention is as follows: (1) Vacuum is applied to the lower plenum of the cylindrical fixture. (2) A precut strip of pressure sensitive adhesive coated urethane steering rib is placed over the lower plenum. (3) Once in place, the scrim paper can be removed from the outside surface of the ribs, exposing the adhesive on the outside surface of the steering rib. (4) Compressed air is applied to the upper plenum and the ITB belt is placed around the cylindrical fixture and slid down until it engages completely with the base. (5) Vacuum is applied to the upper plenum, securing the belt in place. (6) Vacuum is removed from the lower plenum and compressed air is applied, forcing the outside surface of the ribbing against the inner circumference of the belt. (7) The belt is then removed; the process can be repeated to apply ribbing to the opposite end of the belt as necessary.
While polyurethane ribs are a preferred material, any suitable material can be used for the steering rib such as other plastics, papers, tapes, and the like. Also, external connections to a source of vacuum and compressed air are located in the ribbing application fixture, or sources of compressed air can be located within the fixture if more convenient.
In
Rollers 19 of
This type of color system having an array of ROS units is generally described in U.S. Pat. No. 6,418,286 and is incorporated by reference into this disclosure.
The cylindrical fixture 9 of this invention consists primarily of the following parts: The domed upper portion 10 of the fixture 9 allows for quick and easy alignment of the belt 3 (shown in
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In summary, the present invention provides a novel electrophotographic marking system, a method of applying a steering rib to an ITB and a novel rib application fixture.
The electrophotographic marking system comprises an intermediate transfer belt (ITB). Thus belt has on its inner surface at least one steering rib, which is configured to guide and steer the ITB during a marking step. The rib or ribs are configured to mate with an aligned abraded or notched roller or surface to keep the belt aligned as it rotates, thus ensures minimum lateral movement during image-on-image registration. These ribs are provided on the ITB by placing the ribs with an adhesive on its outer surface around and on the circumference of a cylindrical fixture and positioning the ITB on the cylindrical fixture over the ribbing and thereby adhering the ribs to an inside surface of the ITB. The steering rib has an adhesive on its external side to facilitate attachment to the inner surface of the belt. The steering rib is composed of a material selected from the group consisting of plastics, paper, and fiberglass with an adhesive on its outer surface. The steering rib, in a preferred embodiment, comprises a polyurethane material. The steering rib is located on two edge portions of the ITB. The steering rib in one embodiment is located on one edge portion of said belt.
This invention also provides a method of applying a steering rib to an ITB of an electrophotographic marking system. This method comprises providing a cylindrical ribbing application fixture, providing in the fixture a base structure, above the base structure is positioned a lower plenum, and above the lower plenum is positioned an upper plenum, then applying a vacuum to the lower plenum to thereby hold in place a precut strip of the ribbing that is positioned around the lower plenum, exposing to an inner surface of the ITB to an outer surface of the steering rib with an adhesive located on the outer surface of the ribbing, removing the vacuum from the lower plenum and applying compressed air to release the ribbing from the fixture, forcing the ribbing with adhesive against an inner circumference of said belt, and removing the belt with the ribbing from the application fixture.
In one embodiment the vacuum is applied to the lower plenum via apertures in the lower plenum. The compressed air is applied to the upper plenum via apertures in the upper plenum. The vacuum and the compressed air are supplied to the fixture from a source external to the fixture or in another embodiment the vacuum and the compressed air are supplied to the fixture from a source internal to the fixture. The ribbing in one embodiment is applied to one inner side of the ITB. In another embodiment, the ribbing is applied to two or more inner locations on the ITB. The ribbing in a preferred embodiment comprises a polyurethane material. The lower plenum and the upper plenum comprise a cylindrical or drum-like structure having a dome in one embodiment positioned above the upper plenum for easy sliding of an ITB over the dome and around the drum. In a second embodiment, the dome is not used on the fixture. Also provided herewith is a cylindrical ribbing application fixture for applying a ribbing to an ITB comprising a base structure. Above the base structure is positioned a cylindrical lower plenum; positioned above the lower plenum and contiguous therewith is a cylindrical upper plenum. The lower plenum has a plurality of vacuum apertures around its circumference, these apertures are configured to apply a vacuum to the ribbing to hold the ribbing in place around the lower plenum before the ribbing is adhered to the ITB. The upper plenum has a plurality of air apertures around its circumference, which are configured to apply compressed air against an inner surface of the ITB to thereby release the ITB from the fixture after the ribbing is adhered to the ITB.
In one embodiment the vacuum and the compressed air are supplied to the fixture from a source outside the fixture. In another embodiment the vacuum and the compressed air are supplied to the fixture from a source internal to the fixture. The lower plenum is configured to receive the ribbing around its circumference and wherein the apertures in the lower plenum are configured to supply a vacuum that holds the ribbing against the lower plenum prior to the ribbing being adhered to the ITB. Obviously, the fixture of this invention is configured to apply the ribbing against an inner surface of all sizes of ITB.
It will be appreciated that variations of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Also that 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.
