Electrophotography – Cleaning of imaging surface – Web
Reexamination Certificate
1999-11-24
2001-06-26
Grainger, Quana M. (Department: 2852)
Electrophotography
Cleaning of imaging surface
Web
C015S256520
Reexamination Certificate
active
06253056
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to an electrostatographic printer or copier, and more particularly concerns a device for cleaning the backside of a photoreceptor belt used therein.
In an electrophotographic application such as xerography, a charge retentive surface (i.e., photoconductor, photoreceptor or imaging surface) is electrostatically charged and exposed to a light pattern of an original image to be reproduced to selectively discharge the surface in accordance therewith. The resulting pattern of charged and discharged areas on that surface form an electrostatic charge pattern (an electrostatic latent image) conforming to the original image. The latent image is developed by contacting it with a finely-divided, electrostatically attractable powder referred to as “toner”. Toner is held on the image areas by the electrostatic charge on the surface. Thus, a toner image is produced in conformity with a light image of the original being reproduced. The toner image may then be transferred to a substrate (e.g., paper), and the image affixed thereto to form a permanent record of the image to be reproduced. Subsequent to development, excess toner left on the charge retentive surface is cleaned from the surface. This process is well known, and useful for light lens copying from an original, and printing applications from electronically generated or stored originals, where a charged surface may be image-wise discharged in a variety of ways. Ion projection devices where a charge is image-wise deposited on a charge retentive substrate operate similarly.
One type of charge retentive surface typically utilized in the electrostatographic reproduction device is a photoreceptor belt having a base of flexible material. The photoreceptor belt is entrained about a plurality of support rollers so as to form a closed loop path. The photoreceptor belt is driven about the closed loop path to present particular areas of the photorceptor belt sequentially into association with electrographic process stations to form desired reproductions. Adhered to the backside of the photoreceptor belt is a substrate polycarbonate known as anti curl back coating. The purpose of this coating is to balance the stresses within the photoreceptor belt and control edge curling. Over time as a photoreceptor belt repeatedly travels around the sharp corners of rollers, backer bars, and other surfaces, the anti curl back coating begins to wear and flake off in the form of low charged negative particles. As a result a build up of anti curl back coating particles occurs on all parts of the module which come in contact with the anti curl back layer. Additionally, toner particles from the development system, the imaging surface cleaner, and toner airborne in the xerographic module are deposited on the back of the belt. In particular, there is a buildup of particles on the drive roller, the backer bars, and in the Acoustic Transfer Assist (ATA). Debris particles on the drive roll cause the coefficient of friction of the drive roller to drop appreciably. This buildup of particles on the backside of the photoreceptor belt and drive roller may adversely affect performance of the photoreceptor belt as it is driven about the closed loop path and, ultimately, overall performance of the reproduction apparatus. In a non-contact development system, such as Hybrid Scavengeless Development (HSD), the spacing between the developer and the imaging surface is important. When debris builds up on the developer backer bars, the photoreceptor is lifted off the backer bars causing the spacing in the development nip to decrease. When this occurs in a particular location, or several different locations on the developer backer bars, the different development fields produce streaks on copy in the process direction. Excessive debris in the ATA reduces the suction pressure in the ATA and creates transfer defects.
Several mechanisms have been employed for cleaning the backside of the photoreceptor belt. One mechanism includes a stationary pad of a material such as cotton. This pad can easily become saturated with debris, with the period of time required for the pad to become saturated not readily predictable. Saturation of the pad can cause excessive abrasion and scratching of the photoreceptor belt, necessitating frequent inspection and cleaning. To meet high volume copier applications, a cleaner for the backside of a photoreceptor belt or the drive roller is needed that would preserve drive capacity and prevent anti curl back coating contamination to sensitive subsystems.
The following disclosures may be relevant to various aspects of the present invention and may be briefly summarized as follows:
U.S. Pat. No. 4,853,741 to Ku utilizes an indexing web of material, such as a fabric of a non-woven blend of polyester and rayon for example. The web is periodically indexed by a motor, which is coupled to the mechanism. While this mechanism reduces the necessity for frequent inspection, it may scratch the dielectric support web if it picks up any abrasive particles or debris.
U.S. Pat. No. 5,655,205 to Ziegelmuller et al. discloses a mechanism for cleaning the backside of an image bearing dielectric support web including a cleaning blade which engages the backside of the dielectric support web at a predetermined angle so as to wipe the backside of the web. A catch tray attached to the blade collects debris removed from the backside of the web.
SUMMARY OF THE INVENTION
Briefly stated, and in accordance with one aspect of the present invention, there is provided an apparatus for removing electrostatically charged particles from a surface. The apparatus includes an endless, electrically biased conductive foam pad belt having a substrate from which a foam material extends outwardly, rollers about which the foam pad belt is entrained, and a cleaning device for cleaning collected particles from the foam pad. One of the rollers supporting the foam pad belt is a drive roller, which rotates, thereby moving the foam pad belt and causing clean foam material to contact the surface to be cleaned.
In accordance with another aspect of the present invention, there is provided an electrically biased conductive cylindrical foam pad having a cylindrical core about which the foam pad is entrained and a cleaning device for cleaning collected particles from the foam pad. The cylindrical core supporting the cylindrical foam pad rotates, thereby causing clean foam material to contact the surface to be cleaned.
In accordance with yet another aspect of the present invention, there is provided a printing machine of the type having a photoconductive member in the form of an image bearing belt and an apparatus for removing particles which accumulate on the backside of the image bearing belt or the drive roller supporting the image bearing belt. The apparatus for removing accumulated particles includes an electrically biased foam pad, which contacts the surface to be cleaned, and a cleaning device to remove particles collected by the foam pad. The foam pad is caused to advance, thereby bringing the clean portion of the pad into contact with the backside of the image bearing belt or the drive roller supporting the image-bearing belt.
REFERENCES:
patent: 4853741 (1989-08-01), Ku
patent: 5530537 (1996-06-01), Thayer
patent: 5655205 (1997-08-01), Ziegelmuller et al.
patent: 58-142375 (1983-08-01), None
Carlston Richard L.
Casella James M.
Diehl James C.
Lindblad Nero R.
Smith James F.
Grainger Quana M.
Robb Linda M.
Xerox Corporation
LandOfFree
Foam pad for removing electrostatically charged particles... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Foam pad for removing electrostatically charged particles..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Foam pad for removing electrostatically charged particles... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2486367