US3870515A - Method for electrostatic paper stripping by neutralization of transfer charge - Google Patents

Abstract

A method for stripping copy sheets, which are electrostatically supporting toner images, away from an original support surface from which the toner images have been transferred to the copy sheets. The stripping is achieved through the neutralization of the electrostatic charge in the copy sheets which holds them to the surface.

Description

"United States Patent 1191 Kaupp 1451 Mar. 11, 1975 METHOD FOR ELECTROSTATIC PAPER 2,812,709 11/ 1957 Gundlach 96/ 1.4 X I 1 3,045,587 71962 Schwertz .1 96/1.4X IZATION 0F 3,062,536 11/1962 Rutkus et al..... 101/132 X 3,124,457 3/1964 Schwertz 96/l.4 X ['75] lnventor: Norbett H. Kaupp, Newark, N.Y. 3,132,050 5/1964 Huber 118/637 X l 3,240,596 3/1966 Medley et al 96/1 TE [73] Asslgnee: Xerox Corporation, Rochester, N.Y. 3 244 033 4/19 Gundlach h 9 R 3,332,396 7/1967 GUnCllaCh 118/637 2 i 'l' 1,974 3,575,502 4/1971 bppe 355/3 R [21] Appl. No: 433,971 I 9 Application Data 7 Primary Examiner--Roland E. Martin, Jr.

[63] Continuation of Ser. No. 41,668, May 20,1970,

abandoned, -which is a continuation-in-part of "Ser. No. 585,816, Oct.- 11, 1966, abandoned. ABSTRACT 4. 916/ 1 R 96/1 Amethod for stripping copy sheets, which are electro- 7 118/637 35513 statically supporting toner images, away from an origi- [511 P 13/16 G03q 13/2; nal support surface from which the toner images have [58] Fleld Search 96/1 17/1751 been transferred to the copy sheets. The stripping is 118/637 355/3 R achieved through the neutralization of the electro- 'tt' 'th ht h'hhldthmt nc s u she; rsufgigge m e copy see s w 10 o s e, 0

UNITED STATES PATENTS 2,576,882 11/1951 Koole et a1. 226/94 X 9 Claims, 1 Drawing Figure PATENTED 1 I 5 INVENTOR. NORBETT H.KAUPP A TTOR/VEYS METHOD FOR ELECTROSTATIC PAPER STRIPPING BY NEUTRALIZATION OF TRANSFER CHARGE This is a continuation, of application Ser. No. 41,668 filed May 20, 1970, now abandoned, which is a continuation of application Ser. No. 585,816 filed Oct. 11, 1966, and now abandoned. Copending application Ser. No. 200,253 filed Nov. 18, 1971, is a Division of Ser. No. 41,668.

This invention relates to xerography and in particular to a method and apparatus for stripping copy with transferred toner images from a xerographic surface.

In the practice of xerography, as described for example in U.S. Pat. No. 2,297,691, to Chester F. Carlson, a xerographic surface comprising a layer of photoconductive insulating material affixed to a conductive backing is used to support latent electrostatic images. In the usual method of carrying out the process, the xerographic plate is electrostatically charged uniformly over its surface and then exposed to a light pattern of the image being reproduced to thereby discharge the charge in the areas where light strikes the layer. The undischarged areas of the layer thus form an electrostatic charge pattern in conformity with the configuration of theoriginal light pattern.

The latent electrostatic image can then be developed by contacting it with a finely divided electrostatically attractable material such as a powder. The powder is held in image areas by the electrostatic charge on the layer. Where the charge is greatest, the greatest amount of material is deposited; and where the charge is least, little orno material is deposited. Thus, a powdered image is produced in conformity with a light image of the copy being reproduced. The powder is subsequently transferred to a sheet of paper or other surface and suitably affixed thereto to form a permanent print.

The electrostatically attractable developing material commonly used in xerography comprises a pigmented resinous powder referred herein to as toner and a coarse granular material called carrier. The carrier is coated with a material removed in the triboelectric series from the toner so that a charge is generated between the powder and the granular carrier upon mutual interaction. Such charge causes the powder to adhere to the carrier. The carrier, besides providing a charge to the toner, permits mechanical control so that the toner can readily be brought into contact with the exposed xerographic surface for the development of the surface. The powder particles are attracted to the electrostatic image from the granular material to produce a visible powdered image on the xerographic surface.

When xerography is practiced on a cylindrically shaped endless xerographic surface, as a drum described for example in U.S. Pat. No. 3,062,536, to J. Rutkus, Jr., et al., the final copy paper is caused to move in synchronous contact with the drum during a portion of the rotation of the drum. During this time, a potential opposite from the polarity on the toner is applied to the side of the paper remote from the drum to electrostatically attract the toner image from the drum to the copy paper. A puff of air or other mechanical means may then be employed to separate the image bearing paper from the drum. The toner image is then fused to the paper for the production of the final xerographic copy.

During the transfer of the toner image from the drum to the paper, the transfer corotron, which is of a positive polarity when negatively charged toner is applied, deposits at positive charge on the copy paper. The copy paper which is an insulator retains the positive charge while inducing a negative charge in the non-image areas of the xerographic drum. This new charge orientation creates an electrostatic bond between the paper and drum.

To separate the paper from the drum, the electrostatic bond therebetween must first be overcome either mechanically or electrostatically. When an air puffer is used to achieve this separation, a relatively high pressure of air must be employed to overcome the attraction of the paper for the drum. However, when high air pressures are employed, there is a tendency of such air to agitate the unfused toner image on the paper and disrupt the image configuration of the toner. This exhibits itself as puffer smears on the final copy. This blowing of toner powder also results in mechanical dirt problems throughout the functioning elements of the system. Furthermore, when a copy is being separated from the xerographic surface, the high pressure of air repels the tonerbearing paper against the output conveyor with a tonerjarring force especially when the electrostatic bond is small. Mechanical fingers have also been employed to effect stripping. Mechanical fingers, however, have a tendency to scratch and abrade the xerographic surface.

The present invention is directed to a method and apparatus for electrostatically stripping copy from a xerographic surface by neutralizing the electrostatic bond between the paper and xerographic surface. This permits xerographic stripping to be practiced without mechanical instrumentalities.

It is, therefore, an object of the instant invention to strip image-bearing xerographic copy from a xerographic surface electrostatically.

it is another object of the invention to remove the electrostatic charges from xerographic copy.

It is another object of the invention to neutralize the electrostatic bond between xerographic copy and a xerographic surface to cause their separation.

It is a further object of the invention to eliminate toner smears, toner dust contamination, drum abra-,

sion, and other deleterious effects caused by the mechanical removal of image-bearing copy from a xerographic surface.

These and other objects ofthe invention are achieved by neutralizing the electrostatic bond which holds xerographic copy to xerographic surfaces after an electrostatic transfer. This neutralization is accomplished by the use of detacking corona emissions sprayed on the face of the image bearing copy sheet remote from the xerographic surface.

For a better understanding of the 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 drawing wherein the FIGURE is a schematic diagram of an automatic xerographic reproducing machine utilizing the principles of the instant invention.

Referring now to the FIGURE, there is shown an embodiment of the subject invention in a suitable environment such as an automatic xerographic reproducing machine. The machine has a xerographic surface 10 formed by a photoconductive layer on a conductive whichthe drum surface is exposed'to I light source to effect substantiallycomplete. discharge of any residual electrostatic charge remaining thereon.

' backing The surface is formed in the shape of a drum of the xerographic drum;'

An exposure station B, at which a light or radiation pattern of a copy to be reproduced is projected onto the. drum'surface to dissipate the drum charge in the exposed areas thereof thereby forming a latent electrostatic image of the copy to be reproduced;

- A development station C, at which the xerographic developing material including toner particles havingan electrostatic charge opposite to that of the latent electrostatic image, are cascaded over the drum surface,

The instant invention requires no puffer or other mechanical stripping mechanisms. In place thereof, a stripping corotron is positioned across-the xerographic drum downstream from the transfer corotron.-

The stripping corotron is adapted to subject the face of the toner-bearing paper remote from the drum and toner image to a spray of ions having a net polarity opposite from that of the transfer corotron. The purpose of the ion spray of the stripping corotron is to neutralize the bond causing charges placed in the copy paper by the transfer corotron. By neutralizing this charge,

the bond between the paper and drum is removed and the stipping of the paper can be achieved by the pull of gravity on the'paper and the resiliency of the paper which makes it return to its original unbent state.

For the purposes of this illustrative example, let us assume that theoriginal charge placed on the photowhereby thetoner particles adhere to the latent electrostatic image to form a Xero'graphic powder image in the configuration of the copy being reproduced; I

A transfer station D, at which the xerographic powder image is electrostatically transferred from the drum surface to a transfer or support material and then removed from the drum for fusing the image onto the supportmaterial; and;

A drum cleaning and discharge station E, at which the drum surface is brushed to remove residual toner particles remaining thereon-after image transfer,and at a relatively bright It is believed that the'foregoing description is sufficient for thepurposes of this application to show the general operation of the xerographic reproducing ap- Paratus. V As the drum shaped surface rotates past the developmentstation C, a suitable backing material'12 such as paper is brought into contact with the xerographic sur? face 10 by first sheet feeding mechanisrns14. Other insulating backing materials, such as Mylar or the like, may also be used. The sheet anddrum then move at the same linear speed past a transfer coroton 16 whichacts to electrostatically' draw the toner image from the drum towards the paper. At the same time, however, the electrostatiecharge emitted by the transfer corotron electrostatically tacksthe paper to the drum. The drum and paper then traveltogether to suitable instrumentalities capable of removing the paper from the drum to thereby allow the toner-bearing paper to be trans-.

portedaway by second sheet feeding mechanisms 18, The second sheet feeding mechanisms transport the toner-bearing paper to a fusing station for the production of the final copy. r

Most known machines of this type employ some sort of mechanical instrume'ntalities to strip the imagebearing paper from the'xerographic drums. The puffer, which propelsa jet of air or other aeriform fluid between the paper and drum, is probably the mostcommen means used for stripping. A description of a puffer may be found in the aforementioned Rutkus patent, which patent also more fully describes the other xerographic processing stations referred to above.

conductor is positive and that negative toneriparticles are used to develop the image. In, such case a transfer corotron 16 with a positive DC output greater in magnitudethan the image charges onthe xerographic surface will attract the tonerparticles from the 'xerographic surface to the copy paper to cause the transfer of the image. Such positive emissions as caused by the transfercorotron 16 also tend to buildup a uniform positive charge per unit area on the insulating copy paper. The transfer emissions accepted by the paper in regions overlying the nonimage areas of the photoconductor induce an opposite or negative charge in the conductive substrate portion of thexerographic drum in non-image areas. This charge distribution in nonimage areas of the drum and paper creates an electrostatic attraction therebetween.

The elimination or neutralizationof the electrostatic bond between the paper and drum can be achieved by eliminating-or neutralizing the forces creating the bond. Where the positive transferemissionsremaining in the paper create the bond,equaland opposite negative emissions can remove them. i

The bondbetween, the paper and drum consists of chargeshaving .a constant charge per unit area. It has been determined that the bond causing the charge on the copy paper can be neutralized 'through'the useof an AC corotron which producesan excess of emissions opposite in polarity from the charge in the paper. Such an AC. emission can be achievedthrough the proper se lection of the corotron wire and bias.The selected corotron used for successful detacking of papertraveling at 7.1 inches per second according to the instant invention includes 3.5 mil platinum-iridium wire with a 4,500 RMS volt AC source at 600 CPS with a positive 850 volt DC bias. The wire material and the diameter as well'as the DC bias permits the production of the required excess of. negative emissions. Although both positive and negative ions are emitted, the excess of negative ions will produce the required net negative effect.

The parameters of e the above described corona source are by way of illustration only, and-the invention is operable over an extremely wide range of parameters. The detacking corotron described above was used with the machine of the above referredto Rutkus patent. The paper employed varied from heavier than normal'l 10: pound paper down to tissue type 13 pound paper with no variation in'the effectiveness'ofthe stripping. The wide range of paper'weights usable to practice the invention was considered significent. Paper has an inherenttende'ncy to straighten itself out after being bent, as when moved through an arc of the drum surface during transfer. Even the lightest and most flexible papers tested, when neutralized by the stripping emissions, has the ability to fall from the drum under their own weight and resiliency. Furthermore, the neutralizing effect allowed successful stripping of line copy as well as solid area copy with no readjustments of the stripping corotron and rendered the stripped paper free from virtually all static charges for easy handling thereafter.

Pure DC emissions, equal and opposite from the 'charge in the paper, have also been found capable of eliminating this paper-to drum bond. An ion flow from a DC source, large enough to minimize the bond but just slightly lower than the potential which would repel the'toner back onto the drum, wasalso successfully used. Such an emission source included a 3.5 mil plati num-iridium corotron wire with a negative DC bias to -providea current of 2'microamps per inch when run on the machine of theabove referred to Rutkus patent.

' However, 'the critical rameters to which such a'DC corotron must be held makes the AC corotron more economically feasible. Such parameters include uniformity of cross-sectional diameter of the corotron wire, uniformity of wire material, uniformity of speed between the corotron and image as well as uniformity of input current to the corotron lt was not found necessary vto'hold the AC embodiment to such critical parameters. I

While the instant invention has been described as being carried out on a drum-shaped xerographic surface in an-automatic and continuous machine, it should be realized that the inventionis equally applicable to other xerographic machines, as for example, ones employing continuous beltshaped xerographicsurfaces. In such case, the stripping would preferably take place at a location wherethe belt was being guided around a roller.

In operation, as developed xerographic images on the drum'shaped surface move beyond the development station C, the drum contains residual charges in nonimage areas and higher charges in image areas. The image areas also have charged toner particles in an image-wise configuration corresponding to the object to be reproducedL'The drum with its toner images, then passes to a point just before the transfer corotron 16 at which point a sheet of copy paper contacts the drum for concurrent movement therewith. Passage of the paper and image bearing xerographic surface beneath the first or transfer corotron 16 acts to produce an ion flow opposite in polarity from the charge on the toner to thereby electrostatically transfer the toner image from the drum to the paper and to electrostatically tack the paper to the drum. Continued movement of the ation of the final permanent copy.

The stripping corotron has an extended utility in that it is usable to decrease the electrostatic bond between the copy and the drum to a less than copy stripping amount. In such case a mechanical stripper, such as a puffer, would be used in combination with the bond decreasing corotron to effect the final removal of the copy from the drum. Greatly reduced puffing pressure, however, would be needed and many of the problems caused by puffing would be minimized.

It is obvious that the stripping corotron needed to carry out the instant invention is readily adapted for incorporation into existing commerical xerographic machines. It isalso usable for making fused and unfused masters as well as conventional zerographic copy. The various polarities described are also illustrative since they could obviously be varied by one skilled in the art to effect the same paper stripping ability, as for example, in the stripping of positive copy made from negative optical originals.

While the present invention, as to its objects and advantages, has been described herein as carried out in specific embodiments thereof, it is not desired to be limited thereby; but it isintended to cover the invention broadly within the spirit and scope of the appended claims.

I claim:

1. A method of producing xerographic copy including the steps of forming on a member a developable latent electrostatic image having an electrical charge pattern of image and non-image areas,

.developing the image on the member with charged toner particles, moving an insulating backing sheet into contact with the surface of the member in registration with the developed image,

electrostatically transferring the toner particles to the insulating backing sheet with direct current ion emissions opposite in polarity from the charge on the toner particles, and

subjecting the sheet with toner' images to alternating ion emissions from an ion emitting device spaced therefrom to substantially eliminate the eletrostatic bond between the backing sheet and the member created by the electrostatic transferring.

2. The method as set forth in claim 1 wherein the subjecting of the sheet is accomplished with a corotron emitting both positive and negative ion emissions but with an excess of emissions of the polarity'the same as that on the toner particles.

3. The method as set forth in claim 1 wherein the subjecting of the sheet is accomplished with a corotron having an alternate current power source with a direct current bias.

4. In the method of producing xerographic copy which includes the steps of charging a cylindrically shaped photoconductive member with an electrostatic charge, exposing the charged member to dissipate the charge in a patterned configuration of image and nonimage areas corresponding to an object to.be reproduced, developing the surface of the exposed member with charged toner particles to create a toner image, moving the leading edge of an insulating backing sheet into contact with the surface of the photoconductive member so that the sheet is in registration with the toner image and electrostatically transferring the toner particles to the insulating backing sheet with emissions of a single polarity the improvement comprising,

7 subjecting the sheet 'withthe toner image thereon to ion emission of alternating polarity to thereby decrease the electrostatic bond-between the backing sheet and photoconductive member created by the electrostatic transfer. v 5. in the method. of producing xerographic copy which includes the step of forming a'developable latent electrostatic image on a member, developing the surface .of'the member with charged toner particles of a first polarity to create toner images, sequentiallymoving insulating backing sheets into contact with the surface .of the member in registration with the toner im ages thereon and electrostatically transferring the toner particles to the insulating backing sheet with direct current ion emissions, the improvement comprising,

subjecting thesh'eets with toner images thereon to corotron emissions'of alternating pola'rity with the majorityof emissions being of the 'same polarity as the charge on the toner particles to thereby decrease the electrostatic bond between the backing sheets and member created by the electrostatic transfer to thereby permit the toner bearing backing sheet to fal'l'frornthe member. 6. A method of transferring charged xerographic toner images from a developed latentelectrostatic im-' age-bearing member toinsulating backing-sheets, and

I of stripping the toner-bearing backing sheet from the memberincluding, v

sequentially feeding insulating backing sheets into contact'with the developed member withthe leading edge ofeach sheet in registration with the leading edge of a developed latent electrostatic image,

bringing the member and sequentially fed backing then bringing the member and sequentially fed backing sheets into the influence of analternating current corotron means positioned on the side of the insulating backing sheetsremote from the member to subject the insulating backing sheets to alternat ing corona emissions to thereby minimize the electros tatic bond between the toner-bearingsheets and the member and; v

catchingthe toner-bearing backing sheets with sheet feed means as they sepa'ratefrom the member.

8. In the'methodIof producing a xerographic copy whichincludes the steps of charging a photoconductive surface with an electrostatic charge, exposing the charged surface to dissipate the charge in an image configuration corresponding to the object to be reproduced, developing the exposed surface with charged electrostatically attach toner images to the backing v sheets and electrostatically tack the backing sheets to the member, then bringing the member and sequentially fed backing sheets into the influence of an alternating cur- I rent corotron means positioned on the side of the insulating backing sheets remote from the member to subject the insulating backing sheets to alternating corona emissions to thereby minimizethe elec trostatic bond between the toner-bearing sheets and the member and, catching the toner-bearing'backing sheets with sheet feed means as theyseparate-from the member. 7-. A method of transferring charged xerographic l toner images from a developed latent electrostatic image-bearing member tojinsulating backing sheets, and

of stripping the toner-bearing backing sheet from the member including,

toner particles and'eleetrostatically transferring the toner'particles to an insulating backing sheet, including electrostatically bonding the backing sheet to the photoconduc'tive surface by applying charges of a first polarity onto thebacking sheet, the improvement, comprising:

subsequently decreasing the electrostatic bonding between the backing sheet andthe photoconductive surface to electrostatically strip the toner-' bearing backing sheet from the photoc'onductive surface,

wherein the electrostatic bonding decreasing step is carried out by applying to the backing sheet corona emissions having a net second polarity opposite from the first polarity charges on the backing sheet and large enough to minimize said electrostatic bonding but lower than the potential which would repel the tonerparticles back onto-the photoconductive surface; and i the backing sheet is then allowed to separate from the photoconductive surface where said surfaceis cylindrical by the self-straightening resiliency of the backing sheet. a '9. The method of claim 8 wherein the corona emissions of the second polarity are applied by an AC. co-

rona generator.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. I 3, 870, 515

DATED 1 March 11, 1975 INVENTORtS) Norbett H. Kaupp It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Page 1, line 10, change "continuation-in-part" to --continuation--.

Col. 4, line 13, change "stipping" to -stripping-.

Col. 6, line 12, change "zerographic" to -xerographic.

fiigned and Sealed this twenty-third Day of September1975 [SEAL] Arrest:

RUTH C. MASON C. MARSHALL DANN i-tnvsring Officer ('mnmixxr'mu'r ujlau'nrs and Trademarks Dedication 3,870,515.N0rbett H. Kaupp, Newark, N.Y. METHOD FOR ELECTRO- STATIC PAPER STRIPPING BY NEUTRALIZATION OF E. Patent dated Mar. 11, 1975. Dedication filed Oct. 21, 1982, by the assignee, Xerox Corp.

Hereby dedicates to the Public the entire remaining term of said patent.

[Ofiicial Gazette July 12, 1983.]

Claims (9)

1. A method of producing xerographic copy including the steps of forming on a member a developable latent electrostatic image having an electrical charge pattern of image and non-image areas, developing the image on the member with charged toner particles, moving an insulating backing sheet into contact with the surface of the member in registration with the developed image, electrostatically transferring the toner particles to the insulating backing sheet with direct Current ion emissions opposite in polarity from the charge on the toner particles, and subjecting the sheet with toner images to alternating ion emissions from an ion emitting device spaced therefrom to substantially eliminate the eletrostatic bond between the backing sheet and the member created by the electrostatic transferring.

2. The method as set forth in claim 1 wherein the subjecting of the sheet is accomplished with a corotron emitting both positive and negative ion emissions but with an excess of emissions of the polarity the same as that on the toner particles.

3. The method as set forth in claim 1 wherein the subjecting of the sheet is accomplished with a corotron having an alternate current power source with a direct current bias.

4. In the method of producing xerographic copy which includes the steps of charging a cylindrically shaped photoconductive member with an electrostatic charge, exposing the charged member to dissipate the charge in a patterned configuration of image and non-image areas corresponding to an object to be reproduced, developing the surface of the exposed member with charged toner particles to create a toner image, moving the leading edge of an insulating backing sheet into contact with the surface of the photoconductive member so that the sheet is in registration with the toner image and electrostatically transferring the toner particles to the insulating backing sheet with emissions of a single polarity the improvement comprising, subjecting the sheet with the toner image thereon to ion emission of alternating polarity to thereby decrease the electrostatic bond between the backing sheet and photoconductive member created by the electrostatic transfer.

5. In the method of producing xerographic copy which includes the step of forming a developable latent electrostatic image on a member, developing the surface of the member with charged toner particles of a first polarity to create toner images, sequentially moving insulating backing sheets into contact with the surface of the member in registration with the toner images thereon and electrostatically transferring the toner particles to the insulating backing sheet with direct current ion emissions, the improvement comprising, subjecting the sheets with toner images thereon to corotron emissions of alternating polarity with the majority of emissions being of the same polarity as the charge on the toner particles to thereby decrease the electrostatic bond between the backing sheets and member created by the electrostatic transfer to thereby permit the toner bearing backing sheet to fall from the member.

6. A method of transferring charged xerographic toner images from a developed latent electrostatic image-bearing member to insulating backing sheets, and of stripping the toner-bearing backing sheet from the member including, sequentially feeding insulating backing sheets into contact with the developed member with the leading edge of each sheet in registration with the leading edge of a developed latent electrostatic image, bringing the member and sequentially fed backing sheets into the influence of electrostatic means positioned on the side of the insulating backing sheets remote from the member to charge the backing sheets with a charge having a polarity opposite from the charge on the toner particles to thereby electrostatically attach toner images to the backing sheets and electrostatically tack the backing sheets to the member, then bringing the member and sequentially fed backing sheets into the influence of an alternating current corotron means positioned on the side of the insulating backing sheets remote from the member to subject the insulating backing sheets to alternating corona emissions to thereby minimize the electrostatic bond between the toner-bearing sheets and the member and, catching the toner-bearing backing sheets with sheet feed means as they separate from the member.

7. A method of transferring charged xerographic tonEr images from a developed latent electrostatic image-bearing member to insulating backing sheets, and of stripping the toner-bearing backing sheet from the member including, sequentially feeding insulating backing sheets into contact with the developed member with the leading edge of each sheet in registration with the leading edge of a developed latent electrostatic image, bringing the member and sequentially fed backing sheets into the influence of a direct current corotron means positioned on the side of the insulating backing sheets remote from the member to charge the backing sheets with corona emissions having a polarity opposite from the charge on the toner particles to thereby electrostatically attach toner images to the backing sheets and electrostatically tack the backing sheets to the member, then bringing the member and sequentially fed backing sheets into the influence of an alternating current corotron means positioned on the side of the insulating backing sheets remote from the member to subject the insulating backing sheets to alternating corona emissions to thereby minimize the electrostatic bond between the toner-bearing sheets and the member and, catching the toner-bearing backing sheets with sheet feed means as they separate from the member.

8. IN THE METHOD OF PRODUCING A XEROGRAPHIC COPY WHICH INCLUDES THE STEPS OF CHARGING A PHOTOCONDUCTIVE SURFACE WITH AN ELECTROSTATIC CHARGE, EXPOSING THE CHARGED SURFACE TO DISSIPATE THE CHARGE IN AN IMAGE CONFIGURATION CORRESPONDING TO THE OBJECT TO BE REPRODUCED, DEVELOPMENT THE EXPOSED SURFACE WITH CHARGED TONER PARTICLES AND ELECTROSTATICALLY TRANSFERRING THE TONER PARTICLES TO AN INSULATING BACKING SHEET, INCLUDING ELECTROSTATICALLY BONDING THE BACKING SHEET TO THE PHOTOCONDUCTIVE SURFACE BY APPLYING CHARGES OF A FIRST POLARITY ONTO THE BACKING SHEET, THE IMPROVEMENT COMPRISING: SUBSEQUENTLY DECREASING THE ELECTROSTATIC BONDING BETWEEN THE BACKING SHEET AND THE PHOTOCONDUCTIVE SURFACE TO ELECTROSTATICALLY STRIP THE TONER-BEARING BACKING SHEET FROM THE PHOTOCONDUCTIVE SURFACE, WHEREIN THE ELECTROSTATIC BONDING DECREASING STEP IS CARRIED OUT BY APPLYING TO THE BACKING SHEET CORONA EMISSIONS HAVING A NET SECOND POLARITY OPPOSITE FROM THE FIRST POLARITY CHARGES ON THE BACKING SHEET AND LARGE ENOUGH TO MINIMIZE SAID ELECTROSTATIC BONDING BUT LOWER THAN THE POTENTIAL WHICH WOULD REPEL THE TONER PARTICLES BACK ONTO THE PHOTOCONDUCTIVE SURFACE, AND THE BACKING SHEET IS THEN ALLOWED TO SEPARATE FROM THE PHOTOCONDUCTIVE SURFACE WHERE SAID SURFACE IS CYLINDRICAL BY THE SELF-STRAIGHTENING RESILIENCY OF THE BACKING SHEET.

8. In the method of producing a xerographic copy which includes the steps of charging a photoconductive surface with an electrostatic charge, exposing the charged surface to dissipate the charge in an image configuration corresponding to the object to be reproduced, developing the exposed surface with charged toner particles and electrostatically transferring the toner particles to an insulating backing sheet, including electrostatically bonding the backing sheet to the photoconductive surface by applying charges of a first polarity onto the backing sheet, the improvement comprising: subsequently decreasing the electrostatic bonding between the backing sheet and the photoconductive surface to electrostatically strip the toner-bearing backing sheet from the photoconductive surface, wherein the electrostatic bonding decreasing step is carried out by applying to the backing sheet corona emissions having a net second polarity opposite from the first polarity charges on the backing sheet and large enough to minimize said electrostatic bonding but lower than the potential which would repel the toner particles back onto the photoconductive surface; and the backing sheet is then allowed to separate from the photoconductive surface where said surface is cylindrical by the self-straightening resiliency of the backing sheet.

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