US3795025A

US3795025A - Electrophotographic photoreceptor cleaning apparatus

Info

Publication number: US3795025A
Application number: US00308637A
Authority: US
Inventors: K Sadamitsu
Original assignee: Xerox Corp
Current assignee: Xerox Corp
Priority date: 1972-11-21
Filing date: 1972-11-21
Publication date: 1974-03-05
Anticipated expiration: 1991-03-05

Abstract

Photoreceptor cleaning apparatus in an electrophotographic apparatus including a pair of rotating brushes closely enclosed within a brush box and engaging the photosensitive drum. The lower, and first engaged, brush rotates in the same direction as the drum surface. The upper, and second engaged, brush rotates in the opposite direction. An integral planer guide plate and brush flicking member is positioned between and separates the brushes and extends away from the drum. Opposite sides of this guide plate are closely engaged by the brushes. The residual toner on the surface of the drum is swept off away from the drum and along the guide plate towards the center of the brush box and into an appropriate filter.

Description

United States Patent 1 Sadamitsu Mar. 5, 1974 ELECTROPHOTOGRAPHIC PHOTORECEPTOR CLEANING APPARATUS [75] Inventor:

[73] Assignee: Xerox Corporation, Stamford,

Conn.

Katsumi Sadamitsu, lwatsuki, Japan 221 Filed: Nov. 21, 1972 21 Appl. No.: 308,637

[52] US. Cl. 15/256.52, 355/15 [51] Int. Cl G03g 15/00 [58] Field of Search 15/256.52, 256.51, 256.53,

[56] References Cited UNlTED STATES PATENTS 3,411,932 11/1968 Malone ct al l5/1.5 X

3,132,050 5/1964 Huber.. 355/15 Primary Examiner-Leon G/Machlin [5 7 ABSTRACT Photoreceptor cleaning apparatus in an electrophotographic apparatus including a pair of rotating brushes closely enclosed within a brush box and engaging the photosensitive drum. The lower, and first engaged, brush rotates in the same direction as the drum surface. The upper, and second engaged, brush rotates in the opposite direction. An integral planer guide plate and brush flicking member is positioned between and separates the brushes and extends. away from. the

drum. Opposite sides of this guide plate are closely engaged by the brushes. The residual toner on the surface of the drum is swept off away from the drum and along the guide plate towards the center of the brush box and into an appropriate filter.

10 Claims, 1 Drawing Figure ELECTROPIIOTOGRAPHIC PHOTORECEPTOR CLEANING APPARATUS The present invention relates to an improved cleaning device for removing the residual toner from a photosensitive surface in electrophotographic apparatus and more specifically an improved brush cleaning apparatus for increasing the amount of such residual toner which is captured in appropriate filter means, decreasing toner scattering, and therefore reducing the contamination with toner of the interior of the electrophotographic apparatus.

The problems of toner cleaning and machine toner contamination are longstanding ones in the electrophotographic art. Numerous patents and other references, including those cited herebelow, attest to the extensive efforts which have been made in the art to improve surface cleaning within such apparatus. The very fine, dry, electrostatically attractable toner particles which are conventionally used in this art are easily scattered and are very difficult to confine and to remove from surfaces, particularly the surface of the photoreceptor drum in xerographic apparatus. The vigorous brush cleaningaction commonly employed to remove the residual toner from this surface (to which it can adhere strongly) can easily result in dispersing (scattering) this material within the body of the entire apparatus, where it can interfere with machine functions, or seriously damage various components of the apparatus. Particularly, such loose or escaped toner particles are readily attractable to other charged surfaces or charged elements within the apparatus. Conventional brush cleaning brush devices suffer from the disadvantage that if the rotating speed of the brush or brushes is increased to a higher level which is desirable for better cleaning effort, then the toner is more likely to be scattered or thrown out of the brush box by the rapid brush motion, thereby contaminating the interior of the machine.

The prior art in this area includes a number of different brush cleaning structures for xerographic drums. By way of example, dual or tandem cleaning brushes, including brushes apparently rotating in opposite directions, are suggested in earlier patents such as US. Pat. Nos. 3,062,956, 3,103,445 and 3,357,402. Further, the general concept of brush scrapers or flicking blades is well known in the art, as exemplified by US. Pat. No.

. and inexpensive novel structure including a confining brush box and an integral guide plate and brush flicking member located therein commonly engaged between a counterrotating pair of brushes. Further, the brushes are located and driven in'directions relative to the surface being cleaned such that escape of toner from the surface to be cleaned is minimized.

An exemplary embodiment of the present invention is shown and described hereinbelow as incorporated in an otherwise conventional exemplary xerographic apparatus and process. Accordingly, said xerographic process and apparatus need not be described in detail herein, since various printed publications and patents and publicly used machines are available which teach details of various suitable exemplary electrophotographic structures, materials and functions to those skilled in the art. Some examples are disclosed in the books Electrophotography by R. M. Schaffert, and Xerography and Related Processes by John H. Dessauer and Harold E. Clark, both first published in 1965 by Focal Press Ltd., London, England; and the numerous patents and other references cited in these books. All of these references are hereby incorporated by reference in this specification.

Further objects, features and advantages of the present invention pertain to the particular apparatus, steps and details whereby the above-mentioned aspects of the invention are attained. Accordingly, the invention will be better understood by reference to the following description and to the drawings forming a part thereof, which are substantially to scale, wherein:

FIG. 1 is a cross-sectional plan view of an electrophotographic cleaning apparatus in accordance with the present invention.

Referring to FIG. '1, there is shown therein an exemplary cleaning station 10 in accordance with the present invention, together with related exemplary portions of an otherwise conventional xerographic apparatus. Specifically, the cleaning station 10 is shown in operation removing residual toner particles from the surface 13a on the periphery of a photosensitive drum 13. All of the disclosed components would, of course, conventionally be enclosed within the case or skins of the xerographic apparatus.

The cleaning station 10 includes a mateing pair of cleaning brushes, both of which here preferably rotate against the photoreceptor surface 13a at high speed, for example 1,800 revolutions per minute. The two brushes are an upper brush 2a and a lower brush 2b, both closely confined within a matchingly configured brush box 4.

The brush box 4 closely opens to the photoreceptor surface only between upper and

lower edges

4a and 4b thereof, and has a discharge or outlet opening 40. These are its only openings. This outlet opening 4c discharges only into a filter bag 6 within asuction box 5, which it enters through a suction opening 5a. A vacuum is here conventionally maintained on the filter bag 6 by suction means 7 such as a conventional fan or blower shown located at an outlet opening of the suction box 5.

Importantly, as will be discussed in further detail hereinbelow, the pair of

brushes

2a and 2b are kept separated by, and are commonly engaged by, a separating board 3 including integral barrier boards or brush flicking members 3a and 3b.

It may be seen that the cleaning station 10 is conventionally located on the photoreceptor surface 13a between a conventional charging section 14 and transfer section 17.

It will be noted that the elements of the present embodiment are shown in cross-section in FIG. 1 for greater clarity. It will be appreciated, of course, that the components will have regular configurations and end portions. For example, the brush box 4 will, of course, have end walls in the plane of the drawing located at each end of the photosensitive drum l3, and

the

brushes

2a and 2b and the separating board 3 therebetween will obviously extend to these end walls so as to extend across the full width of the photoreceptor 13.

The desired direction of rotation of the

brushes

2a and 2b, and the photosensitive drum 13, are all indicated by the arrows shown thereon. The cleaning station is located on the right side of the drum 13 and a the surface 13a thereof is moving upwardly into the cleaning station 10 with the residual toner particles thereon. The two cleaning brushes are each positioned the same distance from the surface 13a, but are arranged substantially vertically, i.e., with the brush 2a vertically positionedabove the brush 2b. The lowermost brush 2b is therefore the first to engage the surface 13a to be cleaned as the drum 13 rotates. This brush 2b is rotated in a direction about its axis opposite to the direction of rotation of the drum 13 so that the outer portion of its bristles or brush elements are moving in the same direction (only faster) as the surface of the 13a at its point of brushing contact therewith. Thus, the brush 2b continuously brushes toner particles from the surface 13a vertically upwards towards the center of the brush box 4. Further, since this brush 212 surface is rapidly moving uphill or vertically upward at its'area of cleaning engagement, both it and the surface 13a continuously move up and away from opening 4b and therefore combine to prevent the escape downward (out of the brush box 4) of any toner particles. Likewise, the direction of brush scattering will always be in a direction opposite to the opening 4b. The upper brush 2a is the second engaged brush and rotates in the direction opposite to the lower brush 2b. Thus, it engages This provides a more vigorous final brushing. The sur- 7 face 13a is moving out of the cleaning station 10 at this point, past the upper edge 4a of the brush box, but since the surface 13 is moving uphill. or vertically upwards the toner is less likely to escape or be carried past the brush 2a or edge 4a, since there is the additional assistance of gravitational forces acting on the toner particles at this point. This is in addition to the below-described air flows and the above-described directional brushing action of the brush 2a, all of which acts together to direct toner particles away from the opening 4a and toward the center of the brush box 4.

The cooperative action of the closely confining configuration of the brush box 4 is an important part of the above. It may be seen that the brush box 4 closely conforms to and contacts the outer sides of both brushes, extending around to the

edges

4a and 4b, which are closely adjacent to the surface 13a. That is, the only escape path for toner particles from the brush box 4 (other than the outlet or filter discharge opening c) is the small space between the brush box and the surface 13a along the

edges

4a and 4b. Note that the inside of the brush box 4 is in the form of two opposing hemicylinders, each having the diameter of the brushes, and connecting with a narrower central rectangular duct output chute.

The outlet or discharge opening of the brush box 4 defines a conduit extending directly away (perpendicularly) from the photoreceptor surface 13a at the cleaning area. Thus, it serves as an air confining and di recting duct forconducting the toner and air expelled by the brushes away from the brushes into appropriate, suitable, or conventional filtering means, as illustrated here by the connected filter bag 6 and suction box 5. The suction means 7 operating on the suction box 5 reduces the air pressure on the outside of the filter bag 6, which results in drawing air continuously through the filter bag from its interior. This in turn reduces the air pressure within the brush box outlet opening 40 to which it is connected. Since, as previously discussed, the only other opening in the brush box 4 is the small gap at the photoreceptor surface 13a at the

edges

4a and 4b, the entire brush box, including these openings, is subjected to a vacuum which assists in the drawing of all these toner particles into the filter bag 6, in an air flow direction (note arrows) the same as the direction mechanically imparted to the particles by the mutual action of'the two brushes against the barrier board 3., as will be described hereinbelow. These twoparallel and cooperative forces on the particles are assisted by a third force, also acting'in the same direction. This; third force is due to the present structure andin effect provides a positive displacement air pump which di rectly supports and adds tothe airflow provided by the sides of the "brushes are closely engaged and confined by'the brush box 4,the two'brushes act to pump air in- 'wardly into the brush box, in the nature of the well known flexible vane positive displacement fluid pump. The air seals provided by the brush box 4 and separating board 3 are, of course'mot completesince the impellers are bristles here rather thansolid vanes, nevertheless thereis generated by this arrangement a significant low pressure air flow powered by the brush rotation, thus increasing the vacuum on the photoreceptor surface and increasing the positive air flow from the outlet of the brush'box 4 into the filter bag 6, This air flow is in addition to'that which is provided by the su'ction means 7.

All three of the above-described forces acting on the toner particles, as well as the above-described configuration of the brush box, greatly assist in the degree of cleaning, and therefore copy quality, as well as preventing the toner from being scattered outside of the cleaning station 10 in the cleaning operation.

Considering now in further detail the structure and function of the separating board 3, it will be noted that the two

brushes

2a and 2b are positioned closely enough together so that without the separating board 3 they would normally engage and interfere with one another on their common, facing sides. The barrier board 3 provides a continuous planer separating surface extending uninterruptedly between the two brushes. It is preferably constructed as a smooth sheet metal plate. It may be seen that the separating board 3 extends from relatively closely adjacent the surface 13a to beyond the opposite side of the brushes, in a plane perpendicular to, and extending away from, the surface 13a (in a generally horizontal plane). The sides of the

brushes

2a and 2b which are adjacent one another each engage a substantial area of opposing sides of the board 3. This is accomplished by the brushes being mounted so that the board extends substantially inside the normal diameter of the brushes. The separating board 3 extends sufficiently on both sides of the pair of brushes to extend outside of their normal diameters and thus prevent interference between the two brushes. Thus, the sides of the brushes facing one another are substantially compressed and their peripheries are forced to travel in a linear path along the surfaces of the separating board 3 directly away from the photoreceptor drum rather than in their normal circular path. Thus, the toner particles on the brushes cannot escape and are moved linearly away from the photoreceptor surface. The brushes also by this action are in cleaning engagement with most of the surface of the separating board 3, so that the-board 3 cannot accumulate a build-up of toner material. 1

Protruding integrally from the separating board 3 at the outlet side thereof (the side furthest away from the photoreceptor surface 13a) is a barrier board or flicking blades 3a and 3b. The barrier boards 3a and 3b are positioned to flick or scrape the toner off the

respective brushes

2a and 2b. They extend only slightly above the surface of the separating board 3 and are positioned so that the flicking action which occurs from the brushes flicks the toner substantially in the desired direction (away from the photoreceptor surface) thus adding a further propulsion means for the toner particles.

It may be seen that the total separating board 3 has a generally T-shaped structure. The base or principal portion of the T is defined by the main separating board 3 itself. The-barrier boards 3a and 3b together forming v a small cross-bar to the T, extending generally perpendicular to the base or main plane of the separating board 3. The barrier board 3a extends upwardly from the upper surface of the separating board 3 and the barrier board 312 correspondingly extends downward from the lower surface of the board 3. They are preferably formed in an integral portion of the separating board 3, which may be a unitary structure formed by welding, extrusion, casting or the like.

In conclusion, it may be seen that by cooperative effort of all of the above-described components that in the operation of the cleaning station described herein a number of differently generated air flow and mechanical forces cooperatively act to remove substantially all of the toner from the photoreceptor surface at the cleaning station 10 and project it into the filter means. Furthermore, it may be seen that this is accomplished with a simple, inexpensive, and easy to manufacture structure of non-critical components. It allows otherwise conventional cleaning brushes to be operated at higher cleaning speeds with improved cleaning efficiency and reduce scattering or loss of toner. the exemplary embodiment described herein is presently considered to The preferred; however, it is contemplated that further variations and modifications within the purview of those skilled in the art can be made herein. The following claims are intended to cover all such variations and modifications as fall in true spirit and scope of the invention.

What is claimed is:

1. In an electrostatographic apparatus having brush cleaning apparatus for removing particulate material from a moving surface therein, the improvement comprising:

a brush box having an inlet opening positioned closely adjacent to said surface to be cleaned;

a counterrotating driven pair of cleaning brushes located within and substantially enclosed by said brush box, both said brushes being in rapid rotational brushing engagement with said surface to be cleaned through said inlet opening in said brush box;

a separating member positioned between and separating said brushes, said separating member extending away from said inlet opening and surface into the interior of said brush box,

said separating member compressively engaging both of said brushes at their common, facing, sides over a substantial surface area of said brushes;

and brush cleaning means engaging said brushes at a side thereof opposite from said surface and within said brush box.

2. The apparatus of claim 1 wherein said brush box closely confines the opposing, outer, sides of said pair of brushes, and wherein said brushes together with said separating member and said brush box form a positive displacement air pump for pumping air away from said surface to be cleaned.

3. The apparatus of claim 1 wherein said separating member and said brush cleaning means together integrally comprise a generally planar thin T-shaped structure extending continuously between the two brushes, wherein said separating member forms the base of said T and wherein said brush cleaning means comprises integral brush flicking members forming the cross of said T.

4. The apparatus of claim 1 wherein said pair of brushes are positioned in the path of movement of the surface to be cleaned so that the brush first engaging said surface in the direction of movement of said surface brushes said surface in the same direction as said surface is moving, and the second brush engaging said surface brushes said surface against the direction of movement of said surface.

5. The apparatus of claim 1 wherein said pair of brushes are mounted with the first said brush positioned vertically above the second said brush;

and wherein means are provided for moving said surface to be cleaned in a generally vertically upward direction past said cleaning brushes;

and wherein said second and lowermost brush first engages said surface in its upward movement and is rotated to brush upwardly against said surface;

and wherein said surface in its continued upward movement is secondly engaged by said first and uppermost brush, which first brush is rotated to brush downwardly against said surface. I

6. The apparatus of claim 1 wherein opposite interior portions of said brush box having a hemicylindrical configuration conforming to the outside surfaces of the opposite sides of said brushes.

7. The apparatus of claim 6 further including vacuum filter means, wherein said brush box has a central outlet duct extending from said brushes and from said separating member away from said surface to be cleaned, which outlet duct connects with said vacuum filter means.

8. The apparatus of claim 4 wherein said separating member and said brush cleaning means are integral and member and said'brush box form a positive displacement air pump for pumping air away from said surface to be cleaned.

' 10. The apparatus of claim 5 wherein said separating member is a flat plate member extending beyond said brushes and wherein said surface to be cleaned is a xerographic photoreceptor drum.

Claims

1. In an electrostatographic apparatus having brush cleaning apparatus for removing particulate material from a moving surface therein, the improvement comprising: a brush box having an inlet opening positioned closely adjacent to said surface to be cleaned; a counterrotating driven pair of cleaning brushes located within and substantially enclosed by said brush box, both said brushes being in rapid rotational brushing engagement with said surface to be cleaned through said inlet opening in said brush box; a separating member positioned between and separating said brushes, said separating member extending away from said inlet opening and surface into the interior of said brush box, said separating member compressively engaging both of said brushes at their common, facing, sides over a substantial surface area of said brushes; and brush cleaning means engaging said brushes at a side thereof opposite from said surface and within said brush box.

5. The apparatus of claim 1 wherein said pair of brushes are mounted with the first said brush positioned vertically above the second said brush; and wherein means are provided for moving said surface to be cleaned in a generally vertically upward direction past said cleaning brushes; and wherein said second and lowermost brush first engages said surface in its upward movement and is rotated to brush upwardly against said surface; and wherein said surface in its continued upward movement is secondly engaged by said first and uppermost brush, which first brush is rotated to brush downwardly against said surface.

8. The apparatus of claim 4 wherein said separating member and said brush cleaning means are integral and comprise a generally planar and T shaped structure extending between the two brushes, and wherein said surface to be cleaned is a xerographic photoreceptor drum.

9. The apparatus of claim 4 wherein opposite interior portions of said brush box have a hemicylindrical configuration closely conforming to and confining the outside surfaces of the opposite sides of said brushes, and wherein said brushes together with said separating member and said brush box form a positive displacement air pump for pumping air away from said surface to be cleaned.

10. The apparatus of claim 5 wherein said separating member is a flat plate member extending beyond said brushes and wherein said surface to be cleaned is a xerographic photoreceptor drum.