US3809012A

US3809012A - Developer seal

Info

Publication number: US3809012A
Application number: US00309386A
Authority: US
Inventors: G Delvecchio
Original assignee: Xerox Corp
Current assignee: Xerox Corp
Priority date: 1972-11-24
Filing date: 1972-11-24
Publication date: 1974-05-07
Anticipated expiration: 1991-05-07
Also published as: JPS4989538A; NL7315272A; CA984133A; GB1438704A

Abstract

A developer housing seal for electrophotographic apparatus in which a developer with carrier beads which roll over part of the photoreceptor surface is applied to a photoreceptor drum inside a developer housing engaging the drum. This developer housing side or end seal, which may be integrally molded of rubber or other suitable materials, includes a multiplicity of overlapping resilient deflector vanes projecting in the direction of drum surface movement. These vanes angularly impact and deflect the carrier beads inwardly, away from the outside edges of the seals, thereby reducing developer leakage under the seals. The seals are in the form of an arcuate segment of the drum circumference extending partly around the drum, and their outer portion continuously engages the drum surface.

Description

C United States Patent 1 [1 11 3,809,012

Delvecchio May 7, 1974 1 DEVELOPER SEAL 57 ABSTRACT [75] Inventor: George 1). Delvecchlo, Briscoe Cove, A developer housing f l rrophotographic apparatus in which a developer with carrier beads which [73] Assignee: X x C ti Stamford, roll over part of the photoreceptor surface is applied C to a photoreceptor drum inside a developer housing engaging the drum. This developer housing side or end [22] Flled' 241972 seal, which may be integrally molded of rubber or [21] Appl, No.; 309,386 other suitable materials, includes a multiplicity of overlapping resilient deflector vanes projecting in the direction of drum surface movement. These vanes an- [52] U.S. Cl 118/637, 117/175, 118/636 gularly impact and deflect the carrier beads inwardly [51] IIBL Cl G03g 13/00 y from the outside edges of the Seals thereby Fleld of Search ducing developer leakage under the Seals. The Seals are in the form of an arcuate segment of the drum cir- [56] References cued cumference extending partly around the drum, and

U TED STATES PATENTS their outer portion continuously engages the drum sur- 3,635,l96 l/l972 Tsilibes 118/637 face- 3,332,328 7/1967 Roth, Jr. 95/l.7

3,424,131 1/1969 Aser et a1. 118/637 3,640,246 2/1972 Jeromin et a1. 118/629 7 Primary ExaminerMervin Stein Assistant Examiner-Leo Millstein Elaims, Dra yving Figures PATENTED MY 1 um I F/G FIG. 4

DEVELOPER SEAL The present invention relates to an improved seal for electrostatographic apparatus, and more specifically to a seal providing improved retention of xerographic developer.

The problems of developer escape and machine contamination thereby are long-standing ones in the electrostatography art. Developer, which typically includes small carrier beads and very fine toner particles thereon, is very difficult to confine. In operation the developer typically must be dry and electrostatically attractable and carry electrical charges. It is subject to considerable movement and agitation within the machine since it is normally cascaded, magnetically brushed, sprayed or otherwise vigorously applied to an imaging surface to be developed with the developer.

The difficulty of confining or sealing the moving developer within desired development areas of the machine is even further aggravated in the classic xerographic machine configuration in which the surface to be developed is a segment of a curved moving surface of a drum of selenium or other photoconductive materials, and the developer must be confined within a large developer housing opening fitting against the desired segment of the photoreceptor surface without damaging or obstructing this surface.

The peculiar characteristics of developer material and the requirements for protecting the photoreceptor surface preclude the use of many types of seals which would be suitable for different materials or different environments. For example, the seals shown in U. S. Pats. Nos. 2,299,045; 3,524,397; 3,725,937; 2,230,283; and 2,064,703. Thus, in successful commercial practice xerographic developer seals have typically comprised simple frictional sealing strips of suitable resilient materials, or magnetic seals. However, magnetic seals are only suitable with developer having magnetically attractable particles therein, such as steel shot carrier beads. In contrast, the present seals are compatible with either magnetic or non-magnetic developer materials.

Where a typical two component developer is utilized, the photoreceptor surface being developed is subjected to thousands of carrier beads being rolled and bounced over the photoreceptor surface at any given moment of time. Many of these carrier beads acquire a lateral component of movement and therefor tend to roll out to one end (edge) or the other of the photoreceptor drum surface, where the side (end) seals of the developer housing abuts the drum surface. Thus, the laterially moving carrier beads are continuously attempting to escape under the end seals of the developer housing. Further, such developer material tends to build up or accumulate at these developer housing end seals to interfere with or deteriorate the seals and to encourage further developer escape by virtue of its build-up or entrapment adjacent to or under the seals.

Once developer material escapes from underneath the developer housing seals it can scatter within the body of the entire machine. There it can interfere with or seriously damage various machine components. Loose or escaped toner particles are readily attractable to other charged surfaces or charged elements within the apparatus.

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. Shaffert, 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 incoporated 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 an exploded perspective view of developer housing seals in accordance with the present invention, showing the seals in their position at each side of the developer housing, only pulled away from their normal engagement with the xerographic drum for clarity;

FIG. 2 is a top view of the exemplary apparatus of FIG. 1 showing the seals in operation against the photoreceptor surface;

FIG. 3 is an enlarged cross-sectional view of one seal of FIGS. 1 and 2, taken in a plane perpendicular the drum surface and along the drum axis;

FIG. 4 is a further cross-sectional view taken along the line 4-4 of FIG. 3; and

FIG. 5 illustrates the seal of FIGS. 14 in an exemplary xerographic apparatus.

Referring to FIGS. 1-5, there is shown therein an exemplary pair of seals 10 in accordance with the present invention, together with related exemplary portions of an otherwise conventional xerographic apparatus 20,

of which the seals 10 are components. The pair of seals 10 comprise an outboard seal 10a, viewed exteriorly in FIG. 1, and an inboard seal 1012, view interiorly in FIGS. 1 and 5. The two

seals

10a and 10b are substantially identical, here being allochiral or mirror images of one another. The detailed configuration of both of the

seals

10a and 10b is best shown in the enlarged cross-sectional views of FIGS. 3 and 4.

Both of the

seals

10a and 10b are each preferably cast or molded as an integral, unitary structure of Hypalon rubber (chlorosulfonated polyethylene) or other suitable commercially available resilient sealing material which is not deteriorated by the developer materials and which will closely engage the photoreceptor surface, and be slidable thereagainst. The seals may be cast or formed in the desired a'rcuate segment configurations, or made linearly and/or continuously as by strip molding, and then cut to the desired length and curved during installation to the desired configuration. The latter method of construction is possible because of the fact that the seal may be provided, as shown, in a consistent, even, repetitive pattern along its elongate dimension.

It will be appreciated that while the pair of seals 1 is illustrated here as the edge seal of a xerographic developer housing, that the same seal configuration may also be utilized at other xerographic drum locations for sealing purposes. Further, while only one sealing strip is required at each side, as shown, it will be appreciated that it is possible to parallel the sealing strips with additional seals for increased sealing assurance. It will also be appreciated that while the seals R are disclosed here as held against the photoreceptor drum by the developer housing itself, that other or additional means may be utilized to hold the seals in sealing engagement with the drum surface. For example, various conventional tension or retension means.

Referring to FIGS. 1 and 5 it may be seen that the seals are shown as edge seals for a developer housing 12 which is in sealing engagement with a segment of an imaging surface, here comprising a xerographic photoreceptor drum 14. The seals 10 here serve as the sole seal between the edges of the developer housing and the drum M to retain developer 16 within the developer housing 12. Other suitable or conventional seals will, of course, be provided at the top and bottom edges of the developer housing, as for example the magnetic seals l8 schematically illustrated in FIG. 5. The present seals 10 are particularly designed for side (end) seals. That is, they are designed to provide a seal along the edges of the moving imaging surface extending in the direction of movement of that surface.

Each of the seals 10a and 101) are elongate resilient sealing strips fastened to one edge of the developer housing 12 and extending therefrom toward, and into sealing engagement with, the surface of the drum 14. Both of the sealing strips extend in their elongate dimension in the direction of movement of the drum surface 14 along one edge of the drum. That is, the sealing strips are in a plane perpendicular the axis of rotation of the drum, and extend along the circumferiential surface thereof, at each outside edge of the drum. The latteral dimension or width of the sealing strips 10 is quite small in comparison to the width of the imaging surface so as not to obstruct any substantial area thereof. However, a portion of the sealing strip does extend for a short distance onto the surface of the drum 14 within the developer housing I2 as will be explained further herein.

Both of these seals Wu and Itlb, although preferably a unitary structure, may be considered for purposes of description herein as having two portions serving two different functions; a first or outer portion 22 and a second or inner portion 24. The first portion 22 comprises a continuous, uniform and linear sealing member or blade, whose lower surface continuously slidably engages the surface of the drum I4 to provide a continuous seal therewith. (Note FIG. 3). This first portion 22 of the seal also provides for suitable mounting means, such as the rivets illustrated in FIG. 1, along its upper edge for mounting the entire sealing strip projecting from the edges of the developer housing side walls.

The second portion 24 of the seals Mia and 10b comprises a multiplicity of spaced apart and continuously overlapping thin directional deflecting vanes or fins 26 inside of the first seal portion 22. It may be seen that each of the vanes 26 is independently resiliently cantilevered from the inside surface of the first portion 22 of the sealing strips. Each deflecting vane 26 extends angularly inwardly on the imaging surface away from the first portion 22, and also extends angularly in the direction of movement of the imaging surface. Thus, the vanes 26 overlie and extend into a small edge area of the imaging surface. The vanes are positioned edge-wise to the drum surface, and their bottom edges sealingly engage the drum surface.

The primary function of the deflecting vanes 26, comprising the second portion 24 of each seal 10, is to extend deflectingly into the path of any developer on the imaging surface which should attempt to approach the first portion 22 of the seals, to deflect such developer back toward the central portion of the imaging surface and to prevent it from approaching or accumulating adjacent the first portion 22 of the seals. Any carrier beads which would normally roll into engagement with, escape under, or contaminate the seals are resiliently deflected away from the seals by the vanes 26. Since the vanes 26 overlap continuously in the direction of movement of the drum 14 surface, and since the bottom edges of each deflecting vane are in engagement with the drum surface, any carrier bead approaching the seal 10 will impact angularly with the side of at least one surface of the vanes 26 and be deflected inwardly of the drum thereby.

With the seals 10 mounted at the side ofthe drum l4 and extending in a generally vertical direction, as illustrated, it may be seen that the vanes 14 are pointing downwardly. Thus, any developer which might otherwise tend to become entrapped in the spaces between adjacent vanes 26, will tend to be removed by gravational forces, assisted by the fact the vanes tend to independently flex or vibrate from their frictional engagement with the moving drum 14 surface.

It may be seen particularly from FIG. 2 that the sealing strips 10a and llOb located at opposite sides of the developer housing together form a distinctive herringbone pattern as viewed against the drum surface. The multiplicity of vanes 26 have a configuration of uniform comb teeth which are angularly mounted. The angular disposition of the vanes 26 is not critical. A suitable configuration is illustrated here with the vanes 26 all extending linearly from the first portion 22 of the seal at approximately 45, forming an accute angle therewith opening in the direction of movement of the drum surface.

It may be seen that since the multiplicity of vanes 26 are in a continuous band of uniform width in the direction of motion of the drum surface, that they are mutually supportive and to an extent are inherently redundant. Some of the vanes 26 may be frictionally engaged by the drum 141 surface to the extent that they are deformed inwardly against the first portion 26 of the seal, yet the remaining undeflected vanes 26 will continue to extend into the same path and sweep that same edge area of the drum 14 adjacent the first portion 22 clear of developer.

It may be seen that with a multiplicity of small angularly disposed deflecting vanes that an overlapping configuration can be provided with redundant deflecting capability, yet without occupying any substantial width and therefore not obstructing any substantial area of the imaging surface. Yet this multiplicity of small vanes is sufficient to direct the flow of developer on the drum surface away from the seal and from the edge of the drum and thus to inhibit carrier beads from riding on or escaping from, the edge of the drum at the developer housing seal.

In conclusion, as may be seen from the above description, an improved developer seal is disclosed herein which is more effective yet which is simple, inexpensive and easy to manufacture of non-critical components, and is compatible with other existing or conventional xerographic machines components. The exemplary embodiment described herein is presently considered to be 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 within the true spirit and scope of the invention.

What is claimed is:

1. ln electrophotographic apparatus wherein a developer is applied to a moving imaging surface from a developer housing in sealing engagement with a segment of said imaging surface, the improvement in a seal between said developer housing and an edge of said imaging surface comprising:

an elongate resilient sealing strip fastened to at least one edge of said developer housing and extending in said elongate dimension in the direction of movement of said imaging surface along at least one edge of said imaging surface,

said sealing strip having a first portion in continuous linear sealing engagement with said imaging surface,

said sealing strip having a second portion comprising a multiplicity of spaced apart and continuously overlapping directional deflecting vanes inside of said first portion,

said deflecting vanes extending angularly inwardly on said imaging surface from said first portion and extending angularly in the direction of movement of said imaging surface, overlying a small edge area of said imaging surface, to extend deflectingly into the path of said developer on said imaging surface,

said multiplicity of deflecting vanes being positioned to continuously deflect developer away from said first portion of said sealing strip.

2. The apparatus of claim 1 wherein said imaging surface is a cylindrical drum photoreceptor and said seal ing strip is in the form of an arcuate segment of the circumference of said drum at one side of said drum.

3. The apparatus of claim 1 wherein one of said sealing strips are each located at opposite sides of said developer housing and said imaging surface, and together said opposing sealing strips form a herringbone pattern.

4. The apparatus of claim 1 wherein said sealing strip, including said vanes, is an integral unitary molding of rubber.

5. The apparatus of claim 1 wherein each of said vanes is independently resiliently cantalevered from said first portion of said sealing strip. a

6. The apparatus of claim 5 wherein one of said sealing strips are each located at opposite sides of said derubber.

Claims

1. In electrophotographic apparatus wherein a developer is applied to a moving imaging surface from a developer housing in sealing engagement with a segment of said imaging surface, the improvement in a seAl between said developer housing and an edge of said imaging surface comprising: an elongate resilient sealing strip fastened to at least one edge of said developer housing and extending in said elongate dimension in the direction of movement of said imaging surface along at least one edge of said imaging surface, said sealing strip having a first portion in continuous linear sealing engagement with said imaging surface, said sealing strip having a second portion comprising a multiplicity of spaced apart and continuously overlapping directional deflecting vanes inside of said first portion, said deflecting vanes extending angularly inwardly on said imaging surface from said first portion and extending angularly in the direction of movement of said imaging surface, overlying a small edge area of said imaging surface, to extend deflectingly into the path of said developer on said imaging surface, said multiplicity of deflecting vanes being positioned to continuously deflect developer away from said first portion of said sealing strip.

2. The apparatus of claim 1 wherein said imaging surface is a cylindrical drum photoreceptor and said sealing strip is in the form of an arcuate segment of the circumference of said drum at one side of said drum.

5. The apparatus of claim 1 wherein each of said vanes is independently resiliently cantalevered from said first portion of said sealing strip.

6. The apparatus of claim 5 wherein one of said sealing strips are each located at opposite sides of said developer housing and said imaging surface, and are allochiral, and together said opposing sealing strips form a herringbone pattern.

7. The apparatus of claim 6 wherein said imaging surface is a cylindrical drum photoreceptor and said sealing strip is in the form of an arcuate segment of the circumference of said drum.

8. The apparatus of claim 6 wherein said sealing strip, including said vane, is an integral unitary molding of rubber.