Brushing – scrubbing – and general cleaning – Machines
Reexamination Certificate
2000-03-24
2003-02-25
Graham, Gary K. (Department: 1744)
Brushing, scrubbing, and general cleaning
Machines
C015S256530, C015S256510, C015S102000
Reexamination Certificate
active
06523208
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates in general to a web cleaning system and more specifically, to an apparatus and process for cleaning flexible webs.
In the art of electrophotography an electrophotographic member comprising a photoconductive insulating layer on a conductive layer is imaged by first uniformly electrostatically charging the imaging surface of the photoconductive insulating layer. The member is then exposed to a pattern of activating electromagnetic radiation such as light, which selectively dissipates the charge in the illuminated areas of the photoconductive insulating layer while leaving behind an electrostatic latent image in the non-illuminated area. This electrostatic latent image may then be developed to form a visible image by depositing finely divided electroscopic toner particles on the surface of the photoconductive insulating layer. The resulting visible toner image can be transferred to a suitable receiving member such as paper. This imaging process may be repeated many times with reusable photoconductive insulating layers.
The electrophotographic member is often in the form of a flexible multilayered photoreceptor belt comprising a substrate, a conductive layer, an optional hole blocking layer, an optional adhesive layer, a charge generating layer, and a charge transport layer and, in some embodiments, an anti-curl backing layer.
Although excellent toner images may be obtained with multilayered belt photoreceptors, it has been found that as more advanced, higher speed electrophotographic copiers, duplicators and printers were developed, the electrical and mechanical performance requirements have become more demanding. Moreover, new digital color products could not tolerate coating defects at the size levels previously found acceptable for light lens copiers. It has also been found that these electrical and mechanical performance requirements were not being met because of defects in one or more of the coated layers of the multilayered belt photoreceptors. These defects are caused by the presence of dirt particles on the substrate, conductive layer, optional hole blocking layer, optional adhesive layer, charge generating layer, charge transport layer and/or optional anti-curl backing layer. Thus for example, particles of dirt (particulate debris) residing on an uncoated or coated substrate surface during application of coatings to form an electrostatographic imaging member, such as a photoreceptor, can cause bubbles or voids to form in the various applied coating layers. It is believed that the dirt particles behave in a manner similar to a boiling chip that initiates solvent boiling at the location of the particle. This local boiling problem is aggravated when a coating solution is maintained near the boiling point of the coating solvent during deposition of the coating or during drying. The formation of bubbles in a coating is particularly acute in photoreceptor charge generation layer coatings and in charge transport layer coatings. Also, dirt particles tend to trap air during application of a coating and the trapped air expands during drying to form an undesirable bubble in the coating.
Further, any dirt particles residing on one or both major surfaces of an electrophotographic imaging member web substrate or coating thereon can adversely affect adjacent surfaces when the web is rolled up into a roll because the dirt particles cause impressions on the adjacent web surfaces. Because these undesirable impressions can be repeated through more than one overlapping web layer, large sections of a coated web must be scrapped. Where large belts, e.g. ten pitch belts, are to be fabricated, a 10 percent defect rate for a single pitch can result in the discarding of 60 to 70 percent of the entire web because very large expanses of defect free surfaces are required for such large belts.
The sources of the dirt particles include transporting systems, coating systems, drying systems, cooling systems, slitting systems, winding systems, unwinding systems, debris from the electrophotographic imaging member web substrate itself, workers, and the like.
In relatively thin charge blocking layers, such as organopolysiloxane layers applied with a gravure coater, any dirt particles present on the web surface tends to lift the coating layer and cause local coating voids. This also occurs with relatively thin adhesive layers between a charge blocking layer and a charge generation layer. Usually, after a web substrate is coated with the charge blocking layer and adhesive layer, the coated web substrate is rolled up into a roll and transported to another coating station. During unrolling or unwinding of the coated web, static electricity is generated as the outermost ply of the coated web is separated from the roll. This static electricity tends to attract dirt particles to the exposed surfaces of the web.
It has been found that brushing, buffing or other cleaning systems which physically contact the delicate and fragile surfaces of a coated or uncoated electrophotographic imaging member web substrate can cause undesirable scratches in the delicate outer surface of the substrate even if the contact systems are employed in conjunction with electrostatic discharge bars. Cleaning systems that do not contact the coated or uncoated electrophotographic imaging member web substrate, such as air knives and vacuum systems, whether or not assisted with electrostatic discharge bars, are not capable of removing small particles, those having an average particle size of less than about 100 micrometers to 30 micrometers range due to electrostatic attraction and a thin protective inertial air boundary layer on the substrate surface.
The use of a contact cleaner roll making continuous rolling contact with a moving web can remove loose particles of contamination from the web, if the outer surface of the roll has a tacky outer surface. As the web moves over the cleaner roll, the loose particulate matter is transferred from the web to the contact cleaner roll. As this transfer process continues, the transferred contaminants accumulate on the surface of the cleaner roll. The cleaner roll itself eventually becomes contaminated and looses its effectiveness to the point where it can redeposit undesirable particles on a web during the cleaning operation. Thus, the cleaner roll is replaced or cleaned periodically to restore its effectiveness. This is typically accomplished by shutting down the system or process, retracting the cleaner roll, and washing and drying it manually. Attempts to clean these rolls by hand encountered difficulties because the rolls were normally in inaccessible locations. Further, cleaning of the entire outer periphery of a contact cleaning roll required scrubbing of the entire outer peripheral of the contact cleaning roll with cleaning material. Since contact cleaning rolls are mechanically driven, these rolls could not be easily rotated for cleaning unless they are separated from the driving device or removed entirely from the cleaning module. To avoid down time of the system or process, these contact cleaner rolls can be cleaned without interrupting the continuous movement of web through the apparatus by a device for sequential cleaning of the contact cleaner rolls. This type of contact cleaner roll system is disclosed, for example, in U.S. Pat. No. 5,251,348, the disclosure thereof being incorporated herein in its entirety.
When a web coating system utilizes contact cleaning rolls for cleaning a web of one type carrying durable strongly adhering coatings, the same coating system can not be utilized for processing other types of coating operations where the web contains delicate, poorly adhering coatings because the contact cleaning rolls can damage or even remove the delicate coating. Thus, for those webs having delicate coatings, the contact cleaning rolls must be removed to allow the web to pass. Further, removal of such contact cleaning rolls also requires that any web to be coated with a delicate coating must be threaded through the entire coating syst
Muscato Mark
Wisniewski Carl A.
Bade Annette L.
Graham Gary K.
Xerox Corporation
LandOfFree
Flexible web cleaning system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Flexible web cleaning system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Flexible web cleaning system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3134325