US3927937A

US3927937A - Cleaning assembly for an electrostatographic device

Info

Publication number: US3927937A
Application number: US411951A
Authority: US
Inventors: Keyzer Cornelis Jacobus De
Original assignee: Rank Xerox Ltd
Current assignee: Xerox Ltd
Priority date: 1972-11-10
Filing date: 1973-11-01
Publication date: 1975-12-23
Anticipated expiration: 1992-12-23
Also published as: IT999240B; AU6236073A; SE390575B; FR2207843A1; JPS50851A; GB1444794A; ES420425A1; DE2355367A1; NL7215210A; CH574629A5; CA1018243A; FR2207843B1; BR7308771D0; AR200288A1; BE807007A

Abstract

Apparatus for transporting particulate material between first and second zones separated by a dividing wall. A pair of cooperating rollers are sealingly located in an aperture in the wall and are rotated so that material coming into contact with either roll is transported through the nip between the rollers from the first to the second zone. In a particular embodiment, the rollers are located below a cleaning blade acting on a photoreceptor drum and toner dropping from the blade onto the lower roller which runs against the photo-receptor surface is fed into a toner collecting box. The arrangement permits the toner to build up in the toner box above the level of the toner entry point.

Description

[ Dec. 23, 1975 3,469,911 9/1969 355/3 DD 3,728,016 4/1973 Harbour et a1. 355/15 355/15 X [5 1 CLEANING ASSEMBLY FOR AN ELECTROSTATOGRAPHIC DEVICE [75] Inventor:

3,740,789 6/1973 Ticltnor 3,795,025 Sadamitsu........................v

Comelis Jacobus de Keyzer, Venray, Netherlands [73] Assignee: Rank Xerox Ltd., London, England [22] Filed:

Primary Examiner-Fred L. Braun Nov. 1, 1973 2] A l N 411 5 ABS CT 1 l PP- ,9 l A paratus for transporting particulate material between first and second zones separated by a dividing wall. A pair of cooperating rollers are sealingly lo- [30] Foreign Application Priority Data Nov. 10, 1972 Netherlands.......................

725210 cated in an aperture in the wall and are rotated so that material coming into contact with either roll is transported through the nip between the rollers from the In a particular embodiment, the rollers are located below a cleaning blade acting on a photoreceptor drum and toner dropping from the 0 n oo SE n wn D n mo 6 "3 5 a, 2 "5 I w m, mR 5 m3 U My 5 u s 5 3 m. L U C 10 5 mm U IF ,4 1 w 1w blade onto the lower roller which runs against the r collecting photo-receptor surface is fed into a tone References Ciml box. The arrangement permits the toner to build up in UNITED STATES PATENTS the toner box above the level of the toner entry point.

12 Claims, 4 Drawing Figures 351,314 Delmage....................,........... 15/1 U.S. Patent Dec. 23, 1975 Sheet 1 of3 3,927,937

U.S. Patent Dec. 23, 1975 Sheet 2 of3 3,927,937

U.S. Patent Dec. 23, 1975 Sheet 3 of3 3,927,937

CLEANING ASSEMBLY FOR AN ELECTROSTATOGRAPHIC DEVICE This invention relates to an apparatus for transporting particulate material, and is particularly, although not exclusively, concerned with such an apparatus for collecting and storing particulate material, especially toner particles cleaned from the image bearing surface of 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 developed image of toner particles is formed 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 c ing 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 wiper blade 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 carrier particles 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. No. 3,438,706, issued Apr. 15, 1969, to H. Tanaka, et al.; U.S. Pat. No. 3,552,850, issued Jan. 5, 1971, to S. F. Royka, et al.; U.S. Pat. No. 3,634,077, issued Jan. 1 l, 1972, to W. A. Sullivan; U.S. Pat. No. 3,660,863, issued May 9, 1972, to D. P. Gerbasi; U.S. Pat. No. 3,724,019, issued Apr. 3, 1973, to Alan L. Shanly; U.S. Pat. No. 3,724,020, issued Apr. 3, 1973, to Henry R. Till; and U.S. Pat. No. 3,740,789, issued June 26, l973, to Raymond G. Ticknor. Pending applications include German Application DOS No. 2,1 1 L509 by Cannon, filed in Germany, Mar. l0, I971, and published Sept. 23, 1971; Japanese Application No. 46-73818, filed Sept. 23, 197i, (FX/605) and r esponding application filed in the U.S. May 17,

1973, by Shigeru Sadamatsu', and U.S. applications Ser. No. 356,985, filed May 3, 1973, by Richard E. Smith now U.S. Pat. No. 3,848,992 and Ser. No. 356,986, filed May 3, 1973, by Christ S. Hasiotis now U.S. Pat. No. 3,848,993. 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.

A blade cleaning system for a xerographic copying machine which is described, for example, 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.

In previous machines, the cleaning systems, and in particular the means used to transport cleaned-off toner particles to a suitable receptacle for disposal, or to the primary toner supply for re-use, have been found not always to be the most convenient. For example, in the case where a vacuum system is used, filtering arrangements are necessary to clean the air used to draw the toner particles into the receptacle.

[t is an object of the present invention to provide a novel and efficient apparatus for transporting particulate material, and in particular, for collecting and storing particulate material, especially the particles cleaned from an image-bearing surface in an electrostatographic copying machine.

According to the present invention there is provided an apparatus for transporting particulate material from a first zone into a second zone, characterized in that it comprises two rollers mounted for rotation in rolling engagement with one another, the rollers sealingly engaging sealing means provided at the edges of an aperture in a dividing wall between said first and second zones, whereby particles of said particulate material coming into contact with a said roller in the first zone may be transported through the nip formed between the rollers to be retained in the second zone.

Preferably, the rollers are arranged to transport the particles substantially horizontally through the nip, and the second zone comprises a storage chamber including a volume extending above the level of the nip. This enables maximum use to be made of available space, it being possible to pump the particulate material into the storage chamber such that on build-up of a sufficient amount of particles in the chamber, they will extend above the level of the nip.

Advantageously, at least one of the rollers may have a resilient surface.

The apparatus of the invention is particularly wellsuited for use in collecting and storing toner particles cleaned from the photoresponsive surface of an electrostatographic copying machine, such as a xerographic machine, since the cleanedoff particles can be transported away from the cleaning area continuously and progressively as soon as they have been removed from the surface, leaving the cleaning area substantially free of cleaned-off particles after each copy-producing cycle.

An apparatus for transporting particulate material in accordance with the invention, in particular as applied to a xerographic copying machine, will now be described, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 is a simplified, diagrammatic, cross-section of the transporting apparatus;

FIG. 2 is a perspective view of a portion of the apparatus of FIG. 1;

FIG. 3 is a cross-sectional view of part of a xerographic copying machine which incorporates the transporting apparatus of the invention; and

FIG. 4 is a side elevation of part of the machine of FIG. 3.

Referring to FIG. 1, which is for illustrating the principle of the apparatus of the invention, an upper roller 1 and a lower roller 2 are mounted for rotation in rolling engagement with one another, the motions of the two rollers preferably, but not necessarily, being substantially synchronized with one another. Either or both of the rollers may have a resilient surface, and the rollers are mounted in sealing engagement in an entrance aperture, the upper and lower

horizontal edges

3 and 4 of which are shown in FIG. 1, of a storage chamber 5. The vertical edges (not shown in FIG. I) of the aperture in the storage chamber 5 may be suitably shaped in a cusp-like configuration into the nip between the rollers l and 2, such that sealing strips of a resilient material may be secured to the curved surfaces of the cusp to seal against the moving, curved surface of the rollers, at or near the ends of the rollers. Altematively, as shown in FIG. 2, each roller end face may run close to a plane end plate 7. The seal in these circumstances may be provided either by a plane resilient member secured on the end plate 7, and in rubbing engagement with the end faces of the rollers, or, as shown, by a sealing member 8 shaped with a cusp-like portion 9, the apex of which lies close to the nip between the rollers. The curved surfaces of the cusp-like portion 9 are in rubbing engagement with the curved surfaces of the rollers. The sealing member 8, which may be of polyurethane foam, extends upwards and downwards to seal against the

edges

3 and 4.

Suitably, as in the embodiment shown, the upper roller 1 has a rigid surface, such as stainless steel, and the lower roller 2 has a resilient surface, for example, a chloroprene elastomer such as Neoprene.

Alternatively, both rollers may have a resilient surface, or both rollers may have a rigid surface.

Particulate material, which may be collected by the apparatus of the invention by falling onto the lower roller 2, as indicated by arrow 6 (FIG. 1 is carried by the rotation of the rollers through the nip and into the storage chamber 5. Alternatively, or in addition to collection of the particulate material in the way just indicated, a sump of suitable dimensions may be provided below the lower roller 2, at least partially enclosing the roller 2, so that buildup of the particulate material in the sump allows it to be carried by the rollers into the chamber 5.

Once the particulate material is inside the chamber 5, it remains there, being unable to escape because of the seals, described above, around the aperture in the storage chamber 5. The storage chamber 5 extends above the level of the nip, so that when the level of particulate material rises above the level of the nip, the apparatus acts as a pump, and causes the level of particulate material within the storage chamber 5 to continue to rise until the chamber is full.

An embodiment of the apparatus of the invention as applied in the cleaning system of a xerographic copying machine will now be described with reference to FIGS. 3 and 4. The copying machine depicted 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 patents, the web cleaning arrangement of the earlier patents has been replaced by an entire new cleaning assembly.

Referring to FIGS. 3 and 4, 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 1 1, 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 15, a cleaning station constituted by cleaning assembly l6, and a discharge lamp ]7. A document to be copied is carried around a copy drum ]8, 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 casting 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. 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 l0, 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. 3.

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 by 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. 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 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 conditions, 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 90 edge. The blade is of a soft material, such as polyurethane, and in view of the rectangular cross sectional shape may be reversed when wear becomes apparent along one edge.

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 16 may then be fixed into a retracted position 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 this pivotal mounting of the blade holder 33 about the rod 34, blade holder 33 is also pivotally mounted, at 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 corresponding points around the drum, the blade holder 33 is reciprocated longitudinally by reciprocating the rod 34 longitudinally.

Further details of the cleaning assembly are described in a copending US. patent application, Ser. No. 411,851 filed concurrently herewith.

The drum 10 rotates in an anti-clockwise direction, as seen in FIG. 3, 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 10, and causes them to fall towards the lower roller 42 of a particle transporting apparatus of this invention. The roller 42 is mounted within 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 of a 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. 4) which is mounted on one end face of the drum 10. 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 or roller, whereby the roller 42 is substantially synchronized for rolling engagement with the drum 10, and the roller 43 is synchronized for rolling engagement with roller 42.

As shown in FIG. 3, 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. 3. This transports 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 of a 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 shaped as shown in FIG. 2. 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 bottom of 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.

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

Improv ed 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:

1. An apparatus for collecting particles removed from a movable image bearing surface of an electrostatographic apparatus comprising;

means for removing said particles from said movable image bearing surface;

a chamber for receiving said particles;

7 a first roller and a second roller mounted for rotation in rolling engagement with one another, with a nip being formed between said rollers, said rollers being positioned to collect said particles removed by said removing means and to transport said particles through said nip into said chamber.

2. An apparatus as in claim 1, wherein said rollers are arranged to transport said particles substantially horizontally.

3. An apparatus as in claim 2, wherein said first roller is arranged to collect said particles and is positioned in sealing engagement with said image bearing surface.

4. An apparatus as in claim 3, wherein said first roller is positioned below said second roller and further including means to drive said rollers for substantially synchronized rotation with the movement of said image bearing surface.

5. An apparatus as in claim 1 wherein said rollers are positioned in an aperture in a dividing wall between said chamber and said removing means, and wherein sealing means are provided at the edges defined by said aperture, said sealing means sealingly engaging said rollers.

6. An apparatus as in claim 5 wherein said removing means comprises a resilient blade cleaning element.

7. An apparatus as in claim 5 wherein at least one of said rollers has a resilient surface.

8. An apparatus as in claim 7, wherein one of said rollers has a surface of a chloroprene clastomer and the other has a surface of stainless steel.

9. An apparatus as in claim 5, wherein said chamber extends above the level of said nip, whereby said particles in said chamber can build up and extend above the level of said nip.

10. An apparatus as in claim 5 further including means to drive said rollers for substantially synchronized rotation with the movement of said image bearing surface.

11. An apparatus as in claim 5 wherein said first roller includes a resilient surface and wherein said first roller is in rolling engagement with said movable image bearing surface.

12. An apparatus as in claim 11 wherein said first roller is positioned below said second roller.

Claims

1. An apparatus for collecting particles removed from a movable image bearing surface of an electrostatographic apparatus comprising; means for removing said particles from said movable image bearing surface; a chamber for receiving said particles; a first roller and a second roller mounted for rotation in rolling engagement with one another, with a nip being formed between said rollers, said rollers being positioned to collect said particles removed by said removing means and to transport said particles through said nip into said chamber.

8. An apparatus as in claim 7, wherein one of said rollers has a surface of a chloroprene elastomEr and the other has a surface of stainless steel.