US3871762A

US3871762A - Blade cleaning system

Info

Publication number: US3871762A
Application number: US411851A
Authority: US
Inventors: Der Vlasakker Wilhelmus Van
Original assignee: Rank Xerox Ltd
Current assignee: Xerox Ltd
Priority date: 1972-11-10
Filing date: 1973-11-01
Publication date: 1975-03-18
Anticipated expiration: 1992-03-18
Also published as: JPS50849A; IT999241B; FR2206534B1; BR7308767D0; BE807008A; NL7215211A; CA1018242A; AU6235973A; DE2355173A1; FR2206534A1; GB1444795A; CH570641A5; SE386288B; ES420426A1

Abstract

A cleaning assembly for removing residual toner from a photoreceptor comprising a housing including a storage chamber for removed tonger particles. A cleaning device (e.g., blade) is arranged in the housing which has its side edges sealingly engaging the photoreceptor. The housing is suspended for angular movement about a suspension axis extending transversely of the housing and in its operative position it is biased so that its side edges engage the photoreceptor surface. The cleaning device is arranged to be biased into engagement with the photoreceptor by means independent of the housing bias.

Description

United States Patent [191 Van Der Vlasakker Mar. 18, 1975 BLADE CLEANING SYSTEM [75] Inventor: Wilhelmus Van Der Vlasakker,

Venray, Netherlands [73] Assignee: Rank Xerox Limited, London,

England 22 Filed: Nov. 1,1973

21 Appl. No: 411,851

[30] Foreign Application Priority Data Nov. 10, i972 Netherlands....................... 72l52ll [52] US. Cl. 355/15, 15/260551 [51] Int. Cl 003g 15/00 [58] Field of Search 15/256.53, 256.51, 1.5; 355/15; 117/21, 17.5; ll8/637; 96/].4',

[56] References Cited UNITED STATES PATENTS 3,552,850 l/i97l Royka et al l5/256 5l 3,724,019 4/l973 Shanly i5/265.53 3.762.950 10/1973 Royka [5/2565] FOREIGN PATENTS OR APPLICATIONS l24,789 4/l949 Sweden l5/256rSl 2,1 l L509 l,032,957

9/i97l Germany 355/15 6/1966 Great Britain 355/l5 Primary ExaminerEdward L. Roberts Attorney, Agent, or Firm-James .l. Ralabate; Clarence A. Green; Paul Weinstein [57] ABSTRACT A cleaning assembly for removing residual toner from a photoreceptor comprising a housing including a storage chamber for removed tonger particles. A cleaning device (e.g., blade) is arranged in the housing which has its side edges sealingly engaging the photoreceptor. The housing is suspended for angular movement about a suspension axis extending transversely of the housing and in its operative position it is biased so that its side edges engage the photoreceptor surface. The cleaning device is arranged to be biased into engagement with the photoreceptor by means independent of the housing bias.

7 Claims, 7 Drawing Figures saw u or 4 1 BLADE CLEANING SYSTEM This invention relates to a cleaning assembly for an electrostatographic copying machine.

in the well known kind of xerographic copying machine employing a photosensitive member which comprises a drum having a photosensitive surface, a devel oped image of toner particles is forrnfi on the drum, and is then transferred to a sheet of copy material such as paper. Although a very large proportion of the toner particles which form the developed image are usually transferred, there is almost always a small amount of toner remaining on the drum surface after the transfer step. A number of cleaning methods are known, two

such methods being the use of a fur brush, usually in conjunction with a vacuum system, and the use of a wiperblade of a material which will not scratch the delicate surface of the drum. Sometimes it is convenient to recirculate particles collected during cleaning, for example, by means of an auger or a vacuum system, into the primary toner supply, or alternatively the cleaned-off toner particles may be discarded. One reason for discarding cleaned-off toner particles arises in the cascade development process and in the magnetic brush" development process, in which carrier particles are mixed in with the toner particles to carry them onto the drum to develop the image. Some of these carrier particles may find their way to the cleaning station, and so become mixed with the toner particles cleaned from the drum. in the case where the carrier particles are of a magnetic material, such as steel shot, it is possible to arrange for magnetic removal, within the machine, of any carrier particles that are cleaned off with the toner particles.

However, in many cases the carrierparticles are of non-magnetic material, and it may be more convenient to discard the toner particles cleaned from the drum.

A xerographic copying machine in which cleaned off toner particles are discarded is described in U.S. Pat. No. 3,099,943. The machine described in that patent uses a web-type cleaning system, in which a disposable web is advanced in contact with the drum during each copy cycle. The web picks up toner particles, and is discarded after use. A more detailed description of the web cleaning system of this machine is to be found in U.S. Pat. No. 3,099,856.

Exemplary xerographic blade type dry toner cleaning apparatus, to which the present invention relates, is disclosed in U.S. Pat. Nos. 3,438,706, issued Apr. 15, 1969. to H. Tanaka, et al.; 3,552,850, issued Jan. 5, 1971, to S. F. Royka, et al.; 3,634,077, issued .Ian. 11, 1972, to W. A. Sullivan; 3,660,863, issued May 9, 1972, to D. P. Gerbasi; 3,724,019, issued Apr. 3, I973, to Alan L. Shanly; 3,724,020, issued Apr. 3, 1973, to Henry R. Till; and 3,740,789, issued June 26, 1973, to Raymond G. Ticknor. Pending applications include German Application DOS 2,1 I 1,509, by Cannon, filed in Germany Mar. I0, I97], and published Sept. 23, 197l; Japanese Application No. 46-73818, filed Sept. 23, 1971 (FX/605) and its corresponding application tiled in the U.S. May [7, 1973, by Shigeru Sadamatsu; and U.S. applications, Ser. No. 356,985, filed May 3, I973, by Richard E. Smith (D/7300l) and Ser. No. 356,986, filed May 3, 1973, by Christ 8. Hasiotis (D/73l96). Toner cleaning systems with a polyurethene cleaning blade are commercially embodied in the Xerox Corporation 4000 and 3100 xerographic copiers. The present invention is an improvement in this technology, and accordingly these references are hereby incorporated by reference in the present specification description.

The blade cleaning system for a xerographic copying machine described in U.S. Pat. No. 3,724,020 includes a blade which is positioned so that it is in a chiselling" configuration relative to the drum, and uses an auger to transport cleaned-off toner particles away from the cleaning area.

The cleaning systems of known xerographic machines have suffered from the following inconveniences. in the web cleaning system used in the machine mentioned above, the cleaning web material has to be removed and replaced every time a certain num ber of cleaning operations have been carried out. This can be rather inconvenient, since replacement of the web by an unskilled operator might lead to damage to the drum, of the ingress of toner particles or other dirt into the machine. On the other hand, it may be undesir able to call a service engineer every time it is desired to change the web. Although brush cleaning, particularly in conjunction with a vacuum system, is an efficient cleaning system, the necessity to provide a vac uum supply and a filtering arrangement may make it rather inappropriate for use in a small machine of the kind described in the above-mentioned patent specifications. Wiper blade cleaning arrangements, although an efficient means for removing residual toner particles from the drum have suffered from the disadvantage that it is not easy to ensure that all the scraped off toner particles are transported away from the cleaning area.

It is an object of the present invention to provide a novel and efficient cleaning assembly for an electrostatographic copying machine. such as a xerographic machine.

According to the present invention there is provided a cleaning assembly for cleaning residual toner particles from a repetitively-movable image-bearing surface of an electrostatographic copying machine, characterized in that it comprises a housing including a storage chamber for removed toner particles, a cleaning device within said housing for removing said particles from the image-bearing surface, said housing having longitudinal engagement edges co-extensive with said surface in the direction of movement of said surface for sealingly engaging the surface, said housing being suspended for angular movement about a suspension axis which extends transversely of the housing, and said housing in its operative position being urged so that said engagement edges are held in engagement with said surface.

Preferably, the cleaning device is a blade mounted transversely of said housing for engaging said surface.

The cleaning assembly may include means for transporting toner particles removed from the image bearing surface to said storage chamber. Advantageously, the means for transporting toner particles is that set forth in co-pending U.S. patent application. Ser. No. 4ll,95l, filed concurrently herewith. That transporting means conprises two rollers mounted for rotation in rolling engagement with one another, at least the lower of said two rollers having a surface of a resilient material, and said lower roller being mounted for rotation in rolling engagement with said surface, the rollers sealingly engaging sealing means provided at the edges of an entrance aperture of said storage chamber.

A cleaning assembly in accordance with the invention will now be described, by way of example only. with reference to the accompanying drawings, in which:

FIG. 1 is a cross-sectional view of part of a xerographic copying machine incorporating the cleaning assembly of the invention;

FIG. 2 is a side-elevation of part of the machine of FIG. 1;

FIG. 3 is a plan view, with parts cut away, of the cleaning assembly shown in FIG. 1;

FIG. 4 is a plan view of the blade holder of the cleaning assembly;

FIG. 5 is a front elevation of the blade holder shown in FIG. 4; and

FIG. 6 is a cross-sectional view, taken on the line 6-6 of FIG. 4, of the blade holder.

FIG. 7 is a perspective scrap view of part of the machine of FIG. 1, showing how the cleaning assembly of the invention may be retained in its retracted, inoperative position.

The copying machine partially depicted in FIGS. 1 and 2 is the machine described in US. Pat. Nos. 3,099,943 and 3,099,856, with the exception of the cleaning assembly, which in the present case comprises a blade arrangement. Thus, although in all other essential respects the copying machine is the same as that described in the two earlier specifications, the web cleaning arrangement of the earlier specifications has been replaced by an entire new cleaning assembly.

Referring to FlGS. I and 2, a xerographic drum 10, which has a coating of a photoconductive material such as selenium, is mounted for rotation about its axis, so that any given portion of the surface of the drum may be carried past the usual processing stations of a xerographic machine. These stations comprise a charging station constituted by a corona discharge device 11, an optical exposure station 12, a development station 13, a transfer station at which transfer of a developed image to a copy paper sheet is assisted by a corona discharge device 14, a pre-clean corona discharge station IS, a cleaning station constituted by cleaning assembly 16, and a discharge lamp 17. A document to be copied is carried around a copy drum l8, and a flowing image of the document to be copied is projected via lens 19 onto the drum 10 at exposure station 12. Copy paper sheets (not shown) are fed around a copy paper conveyor arrangement 20, to receive the developed image from the drum 10, the developed image being fixed to the copy paper sheet as it passes through a fuser 21.

The cleaning assembly 16 includes a casing 22 and a storage chamber 23 which is in the form of a transparent box-like structure removably attached to the main casting 22 by means, for example, of clips 24, (FIGS. 2 and 3). The cleaning assembly 16 is suspended by means of a hanger 25 on a bar 26, the axis of which is parallel with the axis of the drum 10. The bar 26 is rigidly mounted in the main machine frame (not shown). Hanger 25 is restrained from movements longitudinally of the bar 26 by means of screws 27, but the bent over portion 28 at the upper end of hanger 25 is slotted to permit angular movements of the cleaning assembly 16 about the bar 26. Cleaning assembly 16, in the absence of any restraints, tends to move under gravity into engagement with the drum I0, i.e., into the position shown in the drawings. In order to hold the cleaning assembly 16 in engagement with the drum, two springs 29 are rigidly secured at their upper ends to the bar 26, and at their lower ends bear on the casting 22 to urge it in a clockwise direction as seen in FIG. I.

The longitudinal edges 30 of the casting 22 which engage the circumference of the drum 10 at its two ends, are of the same radius as the surface of the drum. Sealing engagement is achieved along the curved edges 30 key means of foam polyurethane seals (not shown).

Pivotally mounted transversely between the end plates 31 of the assembly 16 is a cleaning blade assembly 32 which is shown in greater detail in FIGS. 4. 5, and 6. A blade holder 33 is pivoted for angular movements on a rod 34 about a horizontal axis extending parallel with the axis of the drum 10. Rod 34 has a central portion of square cross-section, with end portions of circular cross-section which are journaled in the end plates 31 of the cleaning assembly 16. The blade holder 33 includes a generally horizontal arm 35, and a generally vertical arm 36, the arm 35 carrying a weight 37 which urges the arm 36 in a clockwise direction about the pivot rod 34. The cleaning blade 38 is secured in place on the arm 36 by means of a bronze spring clip 39 which extends along the whole length of the blade. The portion of the arm 36 which grips the blade 38 is inclined at an angle such that if the cleaning assembly were in its operative position, but the drum 10 were removed, the blade would make an angle of 32 with the tangent plane at the line of contact between the blade and the drum surface. Under normal operating condi' tions, however, the blade bends through about 10. so that the actual contact angle in operation of the machine is 22 with the tangent plane at the line of contact. The preferred contact angle is 22, but contact angles within the range 22 to 60 have been found satisfactory.

The blade 38 is of rectangular cross-section so that the edge which contacts the drum is a edge. The blade is of a soft material, such as polyurethane rubber. and in view of the rectangular cross-sectional shape. may be reversed when wear becomes apparent along one edge. Other suitable materials for the blade are:

polysiloxane rubber, polytetrafluoroethylene. poly trifluorochloroethylene resin. styrenebutadiene rubber, nitrile rubber, nitro-silicone rubber. flexible polyurethane foam, polyethylene resin, and blends, mixtures and copolymers thereof. The weight 37 causes the blade holder 33 to urge the blade 38 about the pivot rod 34 in a clockwise direction, and therefore into engagement with the drum 10, when the cleaning assembly 16 is in its operative position. In order to remove the drum 10 from the machine. the cleaning assembly 16 is retracted from its operative position by rotating it against the action of spring 29 in an anti-clockwise direction. The cleaning assembly l6 may then be fixed into a retracted position as will be described below with reference to FIG. 7, so that the drum 10 can be removed without any danger of unnecessary contact by the cleaning assembly 16. A stop surface 40 is provided on the casting 22 such that the arm 35 of blade holder 33 engages the stop whenever the cleaning assembly 16 is in its retracted position. This stop prevents the weight 37 from urging the blade 38 beyond a certain position, thus enabling the blade to be maintained out of contact with the drum 10 when the cleaning assembly 16 is in its retracted position.

In addition to the pivotal mounting of the blade holder 33 about the rod 34, blade holder 33 is also pivotally mounted, as its center, about a substantially vertical axis on the pivot rod 34. A pivot pin 41 is provided for this purpose. This additional pivotal movement of the blade holder 33 allows the blade to be self-aligning so that the line of contact between the blade and the drum is always parallel with the axis of the drum.

As a measure aimed at reducing wear by continued contact between certain points of the cleaning blade and cofiesponding points around the drum, the blade holder 33 is reciprocated longitudinally by reciprocating the rod 34 longitudinally. Referring to FIG. 3, one end of the rod 34 carries a compression spring 50 which acts between the end plate 31, and the shoulder formed at the point where the section of rod 34 changes from square to round. The spring 50 thus urges the rod 34 normally away from the end carrying the spring 50. The end of the rod 34 remote from spring 50 carries a cam follower 51, which is urged by the spring 50 into sliding engagement with the cam surface of a cam 52. Cam 52 is in the form of a nylon gear wheel with an inward facing surface which is non-planar, and which on rotation imparts the desired reciprocating motion to the rod 34 via cam follower 5]. Cam 52 is driven by a gear wheel 53 mounted on the drive shaft 54 of drum [0. In order to ensure that different parts of the drum surface are engaged by different parts of the blade on successive rotations of the drum, the cam gear is provided with 67 teeth, whereas the gear wheel 53 on the drum drive shaft is provided with 30 teeth.

The drum rotates in an anti-clockwise direction, as seen in FIG. 1, any residual toner particles (together with any other unwanted particles) remaining on the drum after the transfer operation being cleaned from the drum by the cleaning assembly 16. The cleaning blade 38 scrapes residual toner particles from the surface of the drum l0, and causes them to fall towards the lower roller 42 of a particle transporting apparatus. The roller 42 is mounted with the assembly 16 for substantially synchronized rotation in rolling engagement with an upper roller 43, as well as with the drum 10. The lower roller 42 has a surface ofa chloroprene elastomer such as Neoprene, and the upper roller 43 is of stainless steel. The

rollers

42 and 43 are driven from a gear wheel 44 (FIG. 2) which is mounted on one end face of the drum l0. Roller 42 carries a gear wheel 45 which meshes with gear wheel 44, and roller 43 carries a gear wheel 46 which meshes with gear wheel 45. The number of teeth on each gear wheel is proportional to the radius of its associated drum and roller, whereby the roller 42 is substantially synchronized for rolling engagement with the drum l0, and the roller 43 is synchronized for rolling engagement with roller 42.

As shown in FIG. 1, roller 42 contacts the surface of drum 10, whereby a seal is formed to prevent toner particles from falling under gravity from the cleaning area. However, in case there is any leakage, or accidental spillage, a catch tray 47 is provided directly below the roller 42.

Toner particles (and any other particles) scraped from the drum by the blade 38 fall onto the surface of roller 42, which rotates in a clockwise direction as viewed in FIG. 1. Thistransports the toner particles into the storage chamber 23.

The lower roller 42 and upper roller 43 rotate in sealing engagement with scrapers 48 and 49 respectively, that are mounted along the lower and upper horizontal edges of an aperture in the casting 22. The scrapers 48 and 49 are ofa polyester resin such as Mylar. Seals are also provided at the ends of the

rollers

42 and 43 by means, for example, of polyurethane foam seals having cusp-shaped portions which fit into the nip between the rollers adjacent their ends. Thus, any toner particles remaining on either of the rollers within the storage chamber are scraped off by the scrapers 48 and 49. The scrapers 48 and 49, together with the end seals, accordingly, prevent return flow around the edges of the aperture in the casting 22. Furthermore. the rolling engagement of

rollers

42 and 43 also prevents toner particles within the storage chamber 23 from flowing back into the cleaning area.

As toner particles are scraped off the drum they are transported by the

rollers

42 and 43 into the storage chamber 23, falling initially under gravity into the bottomof storage chamber 23. The level of particles gradually builds up, the seals being adequate to ensure that although the level of toner particles may rise above the level of the nip, the level will continue to rise until the storage chamber 23 is full. At this point, the whole cleaning assembly is removed from the machine. and storage chamber 23 is removed from the casting 22. The collected particles are then discarded.

In order to enable the cleaning assembly to be fixed in its retracted position, for example, to allow the xerographic drum to be removed, the gear wheel 45, which is carried by the lower roller 42, is provided with an axial extension 55 (FIG. 7). The extension 55 has a hollow end portion for engagement by a pin 56 carried by an arm 57. The arm 57 is hinged by a vertical pivot pin 58 on a side plate 59 of the machine. The arm 57 is spring urged away from the gear wheel 45, but can be fixed in the position shown in FIG. 7 by means of a releasable fastener 60. Although only the roller 42 is shown, the whole cleaning assembly 16 can be held in the retracted position by means of the pin 56.

Some of the advantages of the invention described above in relation to its use in a xerographic copying machine are as follows:

Improved cleaning of the xerographic drum surface is achieved, since particles cleaned off the drum are almost immediately transported away from the cleaning area, leaving the cleaning area substantially free of cleaned-off particles after each copy-producing cycle.

The transporting apparatus lends itself to construction in a very compact form which is ideally suited to smaller machines.

The fact that it is possible to use a storage chamber having a volume above the level of the nip between the rollers of the transporting apparatus optimizes the use of available space.

What is claimed is:

l. A cleaning assembly for removing residual particles from a moving image-bearing surface ofan electrostatographic apparatus, comprising:

a housing including a chamber for receiving removed particles, said housing having longitudinal engagement edges extending in the direction of movement of said surface for engaging said surface. said housing being mounted for angular movement about an axis which extends transversely of the housing, and said housing in its operative position being biased so that said engagement edges are held in engagement with said surface; and

a cleaning device within said housing for removing said particles from said image-bearing surface, said device being pivotably mounted in said housing, said device being biased into engagement with said surface by means independent of said housing bias.

2. An assembly as in claim I wherein said device comprises a blade.

3. An assembly as in claim 2 wherein said blade is mounted in a blade holder that is pivotably mounted in said housing about a first axis which extends transversely of said housing and wherein said blade is biased into engagement with said surface by a weight connected to said blade holder.

4. An assembly as in claim 3 wherein said blade holder is pivotably mounted about a second pivot axis perpendicular to said first pivot axis.

ing surface to said chamber.

i i l

Claims

1. A cleaning assembly for removing residual particles from a moving image-bearing surface of an electrostatographic apparatus, comprising: a housing including a chamber for receiving removed particles, said housing having longitudinal engagement edges extending in the direction of movement of said surface for engaging said surface, said housing being mounted for angular movement about an axis which extends transversely of the housing, and said housing in its operative position being biased so that said engagement edges are held in engagement with said surface; and a cleaning device within said housing for removing said particles from said image-bearing surface, said device being pivotably mounted in said housing, said device being biased into engagement with said surface by means independent of said housing bias.

2. An assembly as in claim 1 wherein said device comprises a blade.

5. An assembly as in claim 4 wherein said housing includes a stop surface for engagement by said blade holder to ensure disengagement of said blade from said moving surface when said cleaning assembly is moved away from said moving surface about said axis.

6. An assembly as in claim 5 wherein said housing axis comprises a suspension axis and said housing is spring assisted about said suspension axis into sealing engagement with said moving surface.

7. An assembly as in claim 6 further including means for transferring said particles removed from said moving surface to said chamber.