US3578859A

US3578859A - Mechanical stripping apparatus

Info

Publication number: US3578859A
Application number: US838902A
Authority: US
Inventors: William K Stillings
Original assignee: Xerox Corp
Current assignee: Xerox Corp
Priority date: 1969-07-03
Filing date: 1969-07-03
Publication date: 1971-05-18
Anticipated expiration: 1988-05-18
Also published as: BE752938A; PL81340B1; DE2032371B2; SU443525A3; CA922771A; ES381384A1; FR2054091A5; NL168962B; DE2032371A1; NL7009831A; DE2032371C3; GB1296763A; NL168962C; JPS4931335B1; SE366849B; CH523150A

Abstract

Apparatus to remove an insulating copy sheet from a moving photoconductive surface, the copy sheet being electrostatically tacked to the surface prior to removal by a corona discharge device during a xerographic image transfer operation. A stripping finger is arranged to lift the leading edge of a sheet being advanced on the photoconductive surface and to direct the sheet upwardly away from the surface. A stationary transport having a smooth flat platen to receive a stripped copy sheet in sliding relation therewith is positioned to intercept the leading edge of the stripped sheet and direct the sheet towards a subsequent processing station. Suction ports in the platen located behind the point of contact of the leading edge of the sheet lift the body of the sheet from the stripper finger and hold the sheet in sliding contact with the platen. Lifting means raise the stripper finger away from the moving surface and further stripping of the sheet is accomplished as the sheet slides along the platen and is lifted from the drum surface.

Description

United States Patent [72] Inventor William K. Stillings Primary Examiner-Harvey C. Hornsby Penfield, N.Y. Assistant Examiner-Bruce H. Stoner {2 l] Appl. No. 838,902 Attorneys-Paul M. Enlow, Norman E. Schrader, James J. [22] Filed July 3, 1969 Ralabate, Ronald Zibelli and Thomas J. Wall [45] Patented May 18, 1971 [73] Assignee Xerox Corporation Roche5ter,N.Y, ABSTRACT: Apparatus to remove an insulating copy sheet from a moving photoconductive surface, the copy sheet being electrostatically tacked to the surface prior to removal by a corona discharge device during a xerographic image transfer [54] MECHANICAL STRIPPING APPARATUS operation. A stripping finger is arranged to lift the leading 13 Claims 5 Drawing ES edge of a sheet being advanced on the photoconductive surface and to direct the sheet upwardly away from the surface. A [52] US. Cl tationary transport having a smooth flat platen to receive a 2 stripped copy sheet in sliding relation therewith is positioned [51] II). Cl .l 15/08 to intercept the leading edge of the heet and direct [50] Fleld 0 Search 271/51, 80, the sheet towards a ubsequent processing station Suction P 1 l0, 12, 14 ports in the platen located behind the point of contact of the [56] R f cud leading edge of the sheet lift the body of the sheet from the e erences stripper finger and hold the sheet in sliding contact with the UNITED STATES PATENTS platen. Lifting means raise the stripper. finger away from the 2,895,552 7/1959 Pomper etal 271/74X moving surface and further stripping of the sheet is accom- 3,2l5,056 l 1/1965 Campbell 271/74X plished as the sheet slides along the platen and is lifted from 3,459,477 8/1969 Anthes 355/12 the drum surface.

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MECHANICAL STRIPPING APPARATUS This invention generally relates to xerography, and, in particular, to apparatus for stripping a final support material having an electrostatically transferred toner image thereon from a moving photoconductive surface.

More specifically, this invention relates to apparatus which is particularly well adapted to removing an insulating copy sheet having an electrostatically transferred toner image loosely adhered thereto from the top surface of a moving photoconductor.

In conventional xerography, a photoconductive surface is unifonnly charged and the charged surface then exposed to a light image of an original to be reproduced. Under the in- 'fluence of the light image, the charge on the surface is selectively dissipated to produce what is known as a latent electrostatic image. The charged latent image is developed, or made visible, by attracting oppositely charged toner particles, which are brought into close proximity to the plate surface, into the image areas. The developed image is then generally transferred to a final support material and the image affixed thereto to form a permanent record of the original document.

An insulating material, such as paper, is more conveniently utilized as the final support material in the xerographic art. The copy sheet is placed over the image bearing photoconductive surface and the backside of the sheet subjected to a spray of ionized air. A charge is built up on the sheet having a magnitude and polarity sufficient to electrostatically attract the toner particles from the photoconductive surface to the copy sheet. However, during transfer, a charge opposite to the charge found in the nonimaged areas on thedrum surface is induced in the paper causing the copy sheet to become electrostatically tacked to the drum surface. Removal of the copy sheet and the toner image loosely adhering thereto has long been a problem in the xerographic art.

Mechanical strippers have been employed with varying degrees of success to remove copy sheets from a moving photoconductive surface in automatic xerographic reproducing apparatus. Probably one of the best known and most widely used of these devices is the mechanical air puffer. The puffer is generally positioned to operate on an inverted photoconductive surface, as for example, the bottom portion of a xerographic drum. The copy sheet is stripped from the surface by introducing a stream of air between the copy sheet and the surface and then allowing the sheet to fall away from the photoconductor where it can be picked up by subsequent forwarding means. Because of the volume and velocity of the air stream required to perform the stripping operation, puffing devices are inherently noisy and therefore undesirable. Furthermore, puffing devices have been found to be dirt producing in that the air stream broadcasts'loose toner particles throughout the automatic reproducing apparatus. In some instances working parts of the machine have become contaminated by a buildup of this residual resin based material.

However, perhaps the most serious drawback associated with mechanical puflers and other mechanical strippers known in the art is the fact that they are best utilized when operating on an inverted photoconductive surface. Although this relationship is the most efiicient from a sheet stripping standpoint it is nevertheless undesirable from a practical standpoint because it severely limits where the various xerographic processing stations can be positioned. For example, in a drum-type xerographic machine, paper stripping operations heretofore have been limited to the lower relatively inaccessible 6 oclock drum position rather than more desirable I2 oclock drum position, thereby necessitating theuse of long and torturous paper paths and complex handling equipment.

Electrostatic stripping, a method of stripping in which the electrostatic tacking forces holding the support material to the photoconductive surface are eliminated or neutralized by subjecting the support material to a second corona discharge of sufficient magnitude and polarity to overcome the electro' static bond holding the sheets to the photoconductive surface technique, the insulating copy sheet, loosely supporting a transferred toner image, is moved past a detacking corotron. After the electrostatic charge bonding the sheet to the drum is neutralized, the copy sheet is allowed to fall under the forces of gravity away from the photoconductive surface. The sheet is then picked up by forwarding means and advanced to a subsequent processing station. Here again, in order to effectively remove the sheet and prevent image degredation, the operation must be performed while the photoconductor is in an inverted position so that the copy sheet does not fall back into contact with the photoconductive surface.

It is therefore a primary object of this invention to improve apparatus for removing an electrostatically tacked image bearing support material from a moving photoconductive surface.

It is a further object of this invention to improve apparatus for removing an electrostatically tacked copy sheet from a moving photoconductive surface whereby the copy sheet may be removed when the surface is in any position.

Yet another object of this invention is to improve sheet stripping apparatus whereby a copy sheet can be readily removed from the upper portion of a rotating xerographic drum surface.

A still further object of this invention is to reduce the dirt level in automatic xerographic machines.

These and other objects as well as other further features of V the present invention are attained by means of a thin wedgeshaped stripper finger riding in contact with a moving photoconductive surface and being arranged so that the apex of the wedge moves between the surface and a copy sheet electrostatically tacked thereto to lift the leading edge of the sheet and direct the sheet away from the moving surface, a stationary transport having a flat smooth working surface thereon supported in close proximity to the stripper and positioned to intercept the leading edge of a stripped sheet and direct the sheet towards a subsequent processing station, vacuum means arranged to pull the contacting sheet away from the stripper finger to hold the sheet in intimate contact with the platen wherein further movement of the surface causes the sheet to slide along the platen and to be pulled from the surface, and means to remove the stripper finger from contact with the photoconductive surface.

For a better understanding of the present invention as well as other objects and further features thereof, reference is had to the following detailed description of the invention to be read in connection with the accompanying drawings, wherein:

FIG. I illustrates schematically an automatic xerographic reproducing apparatus employing a preferred embodiment of the paper stripping apparatus of the present invention;

FIG. 2 is a partial side elevation in section of the stripping mechanism shown in FIG. 1 illustrating the leading edge of a copy sheet being lifted from a rotating drum surface;

FIG. 3' is a partial side elevation in section of the stripping mechanism shown in FIG. 1 illustrating a copy sheet being advanced along the stationary transport and showing the stripping finger moved out of contact with the rotating drum surface;

FIG. 4 is a partial perspective view illustrating the stripping finger support and lifting mechanism;

FIG. 5 is a sectional view illustrating the internal construction of the stationary transport.

As shown, the automatic xerographic reproducing apparatus comprises a xerographic plate including a photoconductive layer of a light receiving surface 10 placed on a conductive backing and formed in the shape of a drum, generally designated 11, which is joumaled for rotation in the frame of the machine (not shown) about the horizontal axis of shaft 12. The xerographic plate is rotated in the direction indicated to cause a photoconductive surface to pass sequentially through a plurality of xerographic processing stations.

For the purposes of the present disclosure, the several xerographic processing stations in the path of movement of the has been used with some degrees of success. In this stripping drum surfacemay be'described functionally asfollows:

a charging station A, in which a uniform electrostatic charge is deposited on the photoconductive layer on the xerographic drum; an exposure station B, wherein light or radiation pattern of an original document to be reproduced is projectedonto the drum surface to dissipate the charge found thereon in the exposed areas to form a latent electrostatic image;

a development station C, at which a xerographic developing material having toner particles possessing an electrostatic charge opposite to the charge found on the drum surface in the latent image areas are cascaded over the moving drum surface whereby the toner particles adhere to the electrostatic latent image thus making the image visible in the configuration of the original document to be reproduced;

a transfer station D, in which the xerographic powder image is electrostatically transferred from the drum surface to a .final support material and the final support material removed from the drum surface; and, v

a drum cleaning and toner collecting station E. wherein the drum surface is first treated with corona and then wiped with a doctor blade to remove any residual toner particles remaining thereon after image transfer and collected for reuse in the xerographic process and wherein the drum surface is exposed to an incandescent panel to effect substantially complete discharge of any residual electrostatic charge remaining thereon.

In this preferred embodiment, the charging station is preferably located at near the bottom or 6 o'clock drum position which is generally referenced A in FIG. ll. The charging arrangement consists of a corona charging device 13 including a corona discharge array of one or more corona discharge electrodes extending transversely across the drum surface and which are energized from a high potential source (not shown). The corona discharge electrode is substantially enclosed within a shielding member and is adapted to generate a charge confined to the specific exposure area.

Next subsequent thereto in the path of travel of the xerographic drum is an exposure station B wherein a flowing light image of a stationary original is placed on the moving drum surface. Basically the optical scanning and projecting assembly comprises a stationary transparent copy board M adapted to support the original to be copied, an illuminating means LMP-l to uniformly illuminate the original supported on the copy board, an optical scanning system including an object mirror 16 and an image mirror l8 having lens 17 and being arranged in light projecting relationship with the moving drum surface to project successive incremental areas of the original onto the drum surface. The lens element is positioned beneath the copy board and is arranged to move through a path of travel parallel to the plane of the copy board whereby the subject image of the original is scanned in timed relation to the movement of the light receiving drum surface.

Next adjacent to the exposure station is a de\ eloping station C in which is positioned developing apparatus 20 including a housing 28 having a lower sump portion therein capable of supporting a quantity of two-component developer material. A bucket-type conveyor 27, having any suitable drive means associated therewith, is employed to carry the developer material from the sump area to the upper part of the developer housing where it is deposited into hopper 29. The developer material moves downwardly into contact with the upwardly moving photoconductive drum surface where the toner particles are deposited on the image areas in relation to the charge found thereon to form a developed xerographic image. The unused developer material passes from the development zone back into the lower portion of the developer housing where fresh xerographic toner material is supplied in proportion to the amount deposited on the drum surface from dispensing bottle 21.

Positioned next and adjacent to the developing station is the image transfer station D. Individual sheets of final insulating copy sheets are fed seriatim into the sheet registering and forwarding apparatus 22 from either upper feed tray 35 or lower feed tray 34. Once registered, the sheets are advanced from the register stop rolls 52, 53 into moving contact with the drum surface. The developed image is often then electrostatically transferred from the drum to a copy sheet by means of transfer corotron 24. As will be explained in greater detail below, the sheet is stripped from the drum surface and forwarded along stationary transport 26 into fuser assembly 30.

The image bearing support material stripped from the drum surface is forwarded along stationary transport 26 into the nip between upper fuser roll 31 and lower fuser roll 32. As the roll is rotated in the direction indicated, the rolls deliver both pressure and heat energy stored therein to the copy sheet to fix th image to the support material.

After leaving the fuser assembly, the fused copy sheet is transported through a curved path into a movable guide and drive roll assembly 36. The movable guides can be prepositioned' to either feed a sheet delivered from the fuser into upper feed tray 35 or into a discharge catch tray 37. The machine can be programmed by means of its control logic system to precondition the paper handling equipment to accept simplex copy into the upper tray 35 from which the copy is once again reprocessed as explained above, through the xerographic transfer station to form a duplex image thereon.

The next and final station in the automatic xerographic reproducing apparatus is a drum cleaning and toner recovery station E at which time residual toner on the drum surface is first subjected to a corona generating device 39 which acts to neutralize the electrostatic bond holding the residual toner to the drum station. The residual toner on the drum is then transported into toner cleaning and recovery housing 40 where the residual is removed from the drum surface by means of a doctor blade (not shown). The removed toner is conveyed longitudinally along the drum surface by means of a screw conveyor and deposited in the collecting area in housing 40. The collected toner is then transported through conveyor tubes 41 back into the developer housing by means of an endless chain belt.

It is believed that the foregoing description is sufficient for the purposes of the present application to show the general operation of a xerographic reproducing apparatus employing a sheet stripping apparatus constructed in accordance with the present invention. It should, however, be noted that in this embodiment, this unique stripping apparatus allows the transfer operation to be performed at the top of the xerographic drum. Because of this unique positioning, it is now quite feasible to perform a duplexing operation in a drum-type machine using only a minimum amount of space and with a minimum amount of paper handling equipment. Although not shown, suitable drive means are provided to drive the drum surface, sheet feeding mechanisms, developer conveyors and other operating mechanisms at predetermined speeds relative to each other for the proper coordination of machine operations.

Referring morespecifically to FIGS. 2-5, a paper support material 50 is first fed from either of the two supply trays 34, 35 (FIG. 1) into stop means 51 of sheet registering roll 52. The forward movement of the leading edge of the individual sheet is momentarily interrupted by the stops for a period of time to allow the edge of the sheet to be properly aligned against the stop. Pinch rolls 53 are then cammed into friction driving contact with the sheet and through means of a control mechanism acting through gears 54 and 55 the sheet rapidly accelerated to drum speed. Once at drum velocity, auxiliary drive means (not shown) continue to advance the sheet into contact with the drum surface so that the drum and the copy sheet move into transfer station D at the same linear speed.

A transfer corotron 24 is positioned in the transfer station just downstream from the point at which the paper insulating sufficient strength on the backside of the copy sheet to attract the toner particles from the drum surface to the insulating material. However, the transfer corotron also-tends to build a uniform charge overlying the nonimaged areas on the drum surface. The transfer emissions accepted by the paper in regions overline these nonimaged areas induce a charge in the paper opposite that found in the substrate portion of the xerographic drum. The net charge distribution, therefore, in the nonimage areas creates an electrostatic attraction which tacks the support material to the drum surface.

The total'charge between various copy sheets and xerographic surfaces may vary in proportion to the total amount of nonimaged areas available which can accept a charge. For instance, when the copy has relatively small image areas thereon, the background area is increased to thereby increase the total electrostatic attraction between the paper and the drum. Conversely, when large solid area portions are being developed and transferred-there is a minimum of background area and as such the total amount of induced electrostaticattraction between the insulating material and the drum is proportionally minimized. As can be readily understood, a puffer adapted to separate copy from a drum must be capable of separating the strongest charge bond possible if it is to function correctly. However, maximum puffing pressures acting on sheets with a minimum bond often time result in image smears. Furthermore, maximum puffing pressures also increase the amount of dirt produced by increasing the amount of toner particles broadcast throughout the machine.

As the drum continues to rotate in the direction indicated, the image bearing copy sheet, which is now tacked to the drum surface, is forwarded from under the transfer corotron 24 and the copy sheet is now in a condition to be stripped. lnitial sheet stripping is accomplished in the present invention ;by means of a stripper finger 25. The finger is fabricated from a relatively thin material having nonstick or adhesive properties so that the finger will ride freely on the drum surface in nonfriction contact therewith. As positioned in the automatic machine, the finger is supported upon a shafti60 with the thin member in substantially perpendicular relationship to the drum surface. As shown in FIG. 4, the finger is rotatably supported on the free end of the shaft between stationary member 61 and retaining member 62. The stripper finger is movably supported in the shaft upon a screw 63 passing through an elongated aperture 64 in the finger and the screw threaded in stationary member 61. In assembly, the top of the elongated aperture rests upon screw 63 to support'the finger as shown in FIG. 4.

The opposite end of shaft 60 is journaled for rotation intthe sidewalls of support housing 68 and the housing, in tum, supported by mounting bracket 69 which is secured to the machine frame by screws 67 (P16. 2). Mounting bracket 69 also carries a dependent horizontal support flange 70 in which is secured solenoid SOL-1. The solenoid is single acting device which is arranged to act in opposition to torsion spring 72. Spring 72 is coupled to shaft 60 by means of coupling member 74. A crank arm 71, is secured to one end to shaft 60 with the opposite end of the crank pinned to actuating arm 73 of solenoid SOL-1. With the solenoid deenergized, torsion spring 72 is allowed to assume its equilibrium position. The spring acting through coupling 74, normally supports the finger above the drum as illustrated in FIG. 3. Energization of solenoid SOL-1, pulls crank arm 71 downwardlyto move the stripper finger to a second drum contacting position as shown in FIG. 2.

In operation, solenoid SOL-l is energized by means of the machine logic circuitry (not shown) to move the stripper finger 25 down into contact withthe rotating drum surface just prior to the arrival of the leading edge of a copy sheet. It should be clear that the freely mounted finger, upon contacting the drum, is free to rotate about the shaft 60 so that the finger rides under its own weight in contact with the drum surface. The stripper finger is basically shaped in the form of a wedge and is positioned in the machine so that the apex of the wedge moves between the copy sheet and the rotating drum I which. in turn, extends longitudinally substantially across the width of the platen. The platen 78 forms the bottom of a housing 79 in which is located a vacuum chamber 80 (HO. '5) which is in operative communication with vacuum port 89. The vacuum chamber 80 is connected to a vacuum pump (not shown) through tubing 82 connected to exhaust port 81. The top of the vacuum chamber is described by an incline baffle 86 which acts to uniforrnly decrease the cross-sectional area of the vacuum chamber as you move away from the exhaust port 81. The decrease in area is related proportionally to the head loss in negative pressure across the chamber so that a substantially uniform pressure is maintained at exhaust port 89.

Further advancement of copy sheet 50 causes the leading edge of the sheet to contact platen 78 forward of elongated vacuum port 89. At this point the main body of the sheet, that is, the part of the sheet behind the leading edge thereof comes under the influence of the vacuum being pulled through the vacuum port 89. Sufficient negative pressure is maintained within the vacuum chamber to lift the nonimaged side of the advancing sheet away from the stripping finger and to hold the sheet in intimate contact with the platen as shown in H0. 3. Like the stripper finger, the bottom surface of the platen is coated with a nonsticking adhesive material, such as tetrafluoroethylene, so as to provide a surface over which the copy sheet can readily slide.

With the copy sheet securely held against the flat platen, solenoid SOL-1 is deenergized allowing torsion spring 72 to return to its equilibrium position thereby lifting stripper finger 25 away from the drum surface. At this time the copy sheet is held in sliding relationship with the flat platen 78 so that further rotation of the drum surface advances the copy sheet along the platen towards the next subsequent processing station. Although the negative-pressure acting on the sheet permits the copy sheet to be freely moved along the stationary platen, it nevertheless is strong enough to pull or strip the electrostatically tacked copysheet from the drum surface. In practice, it has been found that sheets of varying bond weight and size can be readily stripped from the top of a rotating drum surface and forwarded along a Teflon" coated platen as herein described when the platen is positioned about 30 to a horizontal plane adjacent to the drum surface and a negative pressure of between 1.5 and 2.5 inches of water maintained at the vacuum port.

In this embodiment of the present invention, the copy sheet is forwarded between upper fuser roll 31 and lower fuser roll 32 of fuser assembly 30. Lower fuser roll 32 is coated with an elastomeric resilient material of a lower durometer than the coating placed on upper fuser roll 31. with the rolls placed in a cooperative pressure driving condition, as shown-in HQ. 2, contact between the roll is maintained over several degrees of arc. A radiant heat source 33 is placed in close proximity with the lower fuser roll and functions to maintain the surface of the roll as a temperature sufficient to heat fuse the toner image supported on the copy sheet. The fuser rolls are rotated so that the copy sheet being forwarded along platen 78 and the rolls are moving at the same linear speed. As can be seen, with the leading edge of the sheet secured between the fuser rolls, the trailing edge of the sheet is free to pass, through the transfer station. Because either the trailing'edge or leading edge of the sheet is being positively driven at sometime during the transfer and stripping operation the present apparatus is fully able to handle cut sheets of support material. The only limitation as to the size sheet that can be handled by the apparatus of the present'invention is the distance that the fuser rolls are located from the transfer station, which in practice is relatively short.

Referring once again to FIG. 5, a switch 83 is mounted within transport housing 79 above vacuum chamber 80. Switch actuator arm 84 passes through the vacuum chamber and platen 78 and extends into the copy sheet path of travel. Switch 83 functions as a sensing device to detect the passage of a copy-sheet through the transport station. Failure of a copy sheet to pass through the station at a predetermined time indicated to the machine control circuitry that a misfeed has occurred causing the machine to be shutdown.

Although a pair of cooperating fuser rolls are disclosed in this embodiment of the invention as a means of further forwarding the cut sheets of material. it should be quite clear to one skilled in the art that any paper forwarding means could be utilized with equal adaptability to further advance a copy sheet leaving stationary transport 26. For example, cooperating pinch rolls could be employed to advance the copy sheet to a subsequent processing station located at a relatively remote position in relation to the transfer station without departing from the teachings of the present invention. While this invention has been disclosed with reference to structure disclosed herein, it is not confined to the details set forth. and this application is intended to cover such modifications or changes as may come within the scope of the following claims.

lclaim:

1. In a xerographic transfer device of the type wherein an insulating sheet is electrostatically tacked to a moving image support member by means of a corona generating device, apparatus to remove the tacked sheet from the moving member including: i

a thin wedge-shaped finger positioned substantially perpendicular to the image support surface of the member with 'the apex of the wedge being arranged to lift the leading edge of the electrostatically tacked sheet from the member and direct the sheet away from said surface,

a stationary transport supported in close proximity to said finger to intercept the leading edge of the stripped sheet and further direct said sheet along a predetermined path of travel,

vacuum means associated with said transport to lift said sheet directly into contact therewith from said wedgeshaped finger and support the sheet in intimate sliding contact with said transport.

2. The apparatus of claim 1 wherein said transport is a smooth surfaced platen along which the sheet is capable of moving in sliding contact therewith.

3. The apparatus of claim 2 wherein said platen is coated with an adhesive material.

4. The apparatus of claim 2 wherein the surface of the platen in sliding contact with said sheet is covered with a coating of tetrafluoroethylene.

5. The apparatus of claim 4 wherein said platen has a vacuum port extending thereacross transverse to the direction of sheet travel, said port being positioned behind the point at which a sheet is directed into contact with said platen whereby the body of the sheet is pulled into intimate contact with said platen.

6. The apparatus of claim 5 having subsequent sheet advancing means to engage a sheet directed along the predetermined path of travel and further advance said sheet.

7. The apparatus of claim 6 wherein said wedge-shaped finger rides in contact with said moving member.

8. The apparatus of claim 7 having further means to remove said wedge from in contact with said member when a sheet is lifted into intimate sliding contact with said platen.

9. Apparatus for transferring a developed toner image from a horizontally supported rotating image support including:

means to bring a sheet of insulating transfer material into synchronous moving contact with a toner image on the rotating drum surface,

a corona generator positioned adjacent to the top of said rotating drum and being arranged to s ray the back of said sheet moving in contact with said rum with an ion discharge of a polarity and strength sufficient to transfer toner material from the drum surface to the support material,

a stripper hinge positioned adjacent said corona generating device in the direction of drum rotation and being adapted to ride in contact with the drum surface to move between the drum surface and the support sheet wherein the sheet is lifted from the rotating surface and directed upwardly away from said surface,

a stationary platen supported in close proximity to said stripper finger to intercept the leading edge of the upwardly moving sheet and direct said sheet along a predetermined path of travel,

a vacuum port extending across said platen transverse to the direction of sheet travel and being positioned behind the point on said platen where the leading edge of the sheet is intercepted, and

means to provide a negative pressure at the port being of sufficient strength to lift the body of the sheet from the stripper finger into close sliding contact with said platen.

10. The apparatus of claim 9 wherein the stripper finger is arranged to ride freely in contact with said drum surface.

H. The apparatus of claim 10 further including means to lift said stripper finger from the drum surface when said sheet is lifted into close sliding contact with said platen.

12. The apparatus of claim 11 wherein the surface of said platen is sliding contact with said sheet is coated with an adhesive material.

13. The apparatus of claim 12 further including subsequent sheet advancing means to engage a sheet directed along the predetermined path of travel and further forward said sheet.

Claims

1. In a xerographic transfer device of the type wherein an insulating sheet is electrostatically tacked to a moving image support member by means of a corona generating device, apparatus to remove the tacked sheet from the moving member including: a thin wedge-shaped finger positioned substantially perpendicular to the image support surface of the member with the apex of the wedge being arranged to lift the leading edge of the electrostatically tacked sheet from the member and direct the sheet away from said surface, a stationary transport supported in close proximity to said finger to intercept the leading edge of the stripped sheet and further direct said sheet along a predetermined path of travel, vacuum means associated with said transport to lift said sheet directly into contact therewith from said wedge-shaped finger and support the sheet in intimate sliding contact with said transport.

9. Apparatus for transferring a developed toner image from a horizontally supported rotating image support including: means to bring a sheet of insulating transfer material into synchronous moving contact with a toner image on the rotating drum surface, a corona generator positioned adjacent to the top of said rotating drum and being arranged to spray the back of said sheet moving in contact with said drum with an ion discharge of a polarity and strength sufficient to transfer toner material from the drum surface to the support material, a stripper hinge positioned adjacent said corona generating device in the direction of drum rotation and being adapted to ride in contact with the drum surface to move between the drum surface and the support sheet wherein the sheet is lifted from the rotating surface and directed upwardly away from said surface, a stationary platen supported in close proximity to said stripper finger to intercept the leading edge of the upwardly moving sheet and direct said sheet along a predetermined path of travel, a vacuum port extending across said platen transverse to the direction of sheet travel and being positioned behind the point on said platen where tHe leading edge of the sheet is intercepted, and means to provide a negative pressure at the port being of sufficient strength to lift the body of the sheet from the stripper finger into close sliding contact with said platen.

11. The apparatus of claim 10 further including means to lift said stripper finger from the drum surface when said sheet is lifted into close sliding contact with said platen.