[1]United States Patent Office 32 1 9,99866 3,199,866 SHEET FEED MECHANISM Roger H. Eichorn, Webster, and Donald L. Pease, Jr., Marion, N.Y., assignors i@ Xerox Corporation, Rochester, N.Y., a corporation of New Yorlc Filed May 24, 1963, Ser. No. 282,952 3 Claims. (Cl. 271-79) This invention relates in general to a sheet feed mechanism and, in particular, to a sheet conveyor n-iechan-isn-i for scriatir@i feedin.- of shee' , material to a xerographic drum. Specifically, the invention relates to an improved sheet gripper iiiechanism, of the type disclosed in copending Roger H. Eichorn application, Serial No. 77,956, filed December 23, 1960, now Patent No. 3,100,109, for a she@-t conveyor that is particularly adapted for use in a xerographic reproducing apparatus, ard wliieh is also suitable for use with comparable types of devices. . In the process of xero.-raphy, for example, as d;sclosed in either Carlson Patent 2,297,691, issued October 6, 1942, or in Carlson Patent 2,357,809, issued September 12, 1944, a xerographic plate, compris;ng a layer of photoconductive insulating material on a conductive backing, is given a uniform electrostatic charge over its surface and is then exposed to the subject matter to be reproduced, usually by conventional proi-,etion techniques. This exposure discharges the plate areas in accordance with the radiation intens:ity which reaches them and thereby creates an electrostatic latent image on or in the plate coating. Development of the i-.nage is effected with developer material or developers which comprise, in general, a rnlxture of a suitable pigmen'@ed or dyed clectroseopic powder, here-inafter referred to as toner, and a gra--ular carrier material, which latter functions to carry and to generate triboelectric charges on the toner. More exactly, the flinction of the granular material is to provide the mechanical control to the powder, or to carry the powder to an image surface and, siiiitiltaneously, to provide alniost complete homogeneity of charge polarity. In the developnient of th-- image, the toner powder is broight into surface contact wcih the xero,-raphic plate and is held thereon electrostatically in a T)attern corresponding to the electrostatic latent imag--. Thereafter, the xero.-raphic powder image is transierred to a support material to which it may be fixed by any suitable means. The invention relates to conveyors and in particular to sheet gripper mechanism for conveying sheet material, such as paper or the like, to contact the xerographic plate in synchronized movement therewith Nvhereby the developed xerographic ima,- e from the xerographic plate is transferred in proper re.-istration onto the sheet material. Because of cost and other considerations, it is desirable to use in the sheet conveyor, roller chair@s haviiig relatively small diameter rollers. It is also desirable to have the sheet grippers carried by the roller chains o'L a minimil-m thickness,- preferably of a thickness corresponding to the thickness of the roller chai-.is. It is apparent that the sheet gripper elemep@'s cooperating with eac]4 other to grip a sheet must be biased i-iito cooperative enga.@ement to securely grip the sheet. Because this biasing force can be relatively large whereas the thickness ol. the individual sheet gripper elements is relatively small, the sheet gripper elements can readily be Patented Aug. 10, 1965 2 twisted or deflected as the sheet gripper is caused by cam action to open to receive or reject sheet rnaterial. It is therefore the principal object of this invention @to improve sheet feedin- meclianisms for use in a xerographic apparatus or similar device. A further object of this invention is to improve sheet gripper devices and their actuators to sheet gripper devices t6 securely grip sheet material without deflect-Ion of the sheet gr-ipper elements. 10 I Another object of this invention is to improve sheet gripper devices for use in a sheet conveyor Nvhereby various sized sheet material can be conveyed. Th.-se and other objects of the invention are attained by rheans of a sheet conveyor includina two endless belts, 15 in the form of roller chains, supported by pulley mea:ns for travel in unison in two spaced substantially parallel planes to transport a sheet gripper mechanism from a sheet receiving station to a sheet delivery station. The sheet gripper mechanism incli-ides a gripper bar connected 20 to the endless belts along a line perpendicular to the spaced planes of travel of the endless belts. The gripper bar supports sheet gripping means including at least one movable gripper having a jaw adapted to cooperate with the jaw of a second gripper to grip a sheet therebetween. 25 Pairs of cam means are located adjacent and between the endless belts at the sheet receiving station and the sheet delivery station. I For a better understandin.- of the invention as well as other objects and further features thereof, reference is 30 had to the following detailed description of the invention to be read in connection with the accompanying drawings, wherein: FIG. 1 is a schematic illustration of a xerographic reproducing apparatus havi.-ig a sheet feed mechanism us35 ing a preferr,-d embodiment of a sheet gripper mecliariism of the invention; FIG. 2 is a perspective view of the sheet feed mechanism of the api)aratus of FIG. 1; FIG. 3 is a top view of a preferred form of paper grip40 per mechanism constructed in accordance with the invention; FIG. 4 is an enlar.-ed view of the paper gripper taken along line 4-4 of FIG. 3; FIG. 5 is an enlarged view taken along line 5-5 of 45 FIG' 3; FIG. 6 is an enlar,@ed view taken along line 6-6 of FIG. 3; FIG. 7 is an enlarged view taken along line 7-7 of 50 FIG. 3; and FIG. 8 is an enlarged exploded view in perspective of a portion of the paper gripper mechanism. As shown, the xerographic apparatus conprises a xerographic plate includ;ng a photoconductive layer or 55 light-receivin.- surface on a conductive backin.a and fo.,-med in the shape of a drum, -enerally designated by numeral 20, which is journaled in a frame to rotate in the direction indicated by the arrow to cause the drum surface sequentially to pass a plurality of xerographic 60 process g stations. For the purpose of the present disclosure, the several xerographic processing stations in the path of mover@ient of the drum surface may be described functionally, as follows: 65 A charging station, at which a uniform electrostatic
[2]3 charge is deposited on the photoconductive layer of thexerograph,'c drum; An exposure station, at which a light or radiation pattern of copy to be reproduced is projected onto tlle drum surface to dissipate the drum char,-e in the exposed areas thereof and thereby form a latent el.-etrostatic image of the copy to be reproduced; A developing station, at wh:ich a xerographic developin- material including toner particles having an electrostatic charge opposite to that of the electrostatic latent image are cascaded over the drum surface, whereby the toner particles adhere to the electrostatic latent image to form a xerographic powder image in the configuration of the copy to be reproduced; A transfer station, at which the xerographic powder ima,-e is electrostatically transferred ftom the drum surface to a transfer material or support surface; and, A drum cleaning station, at which the drum surface is first charged and then brushed or wiped to remove residual toner particles remaining thereon after image transfer, and at which the drum surface is exposed to a relatively bright-li.-ht source to effect sub@tantially complete discharge of any residual electrostatic charge remaining thereon. The charging station is preferably located as indicated by reference character A in the schematic illustration of the apparatus. In general, the char.-ing apparatus or corona charging device 21 includes a corona discharge array of one or more discharge electrodes that extend trainsversely across the drum surface and are energized from a high potential source and are substantially enclosed within a shielding member. Next subsequent thereto in the path of motion of the xerographic drum is an exposure station B provided with an optical scanning or projection system to project a flowing image of a document onto the photoconductive surface of the xerographic drum from a sbitable original. The optical scanning or projection assembly consists of a copyboard in the shape of a drum, hereinafter referred to as copy drum 30, which is adapted to support copy to be reproduced and arranged to rotate in light projection relation to the moving lightreceiving surface of the xerographic plate. Uniform lighting is provided by suitable lamps 31 attached to a slotted light reflector 32 mounted adjacent to the copy drum. A slotted light shield 33, adapted t6 protect the xerographic plate from extraneous light, is positioned adjacent to the surface of the xerographic plate. A slot aperture in the light shield extends transversely to the path of movement of the light-receiving surface of the xerographic drum 20 to permit reflected rays from the copy drum to be directed against a limited transverse area of the liglit-receiving surface as it passes thereunder. To enable the optical system to be enclosed within a relatively sinall cabinet, a folder optical system,including an object mirror 34, a lens 35, and an image mirror 36, is used in the preferred embodiment of the apparatus. A document fed through document guides 37 to the copy drum is removably secured thereon by a suitable gripper mechanism for movement therewith in timed relation to the movement of the xerographic drum whereby a flowing image of the copy is projected onto the xerographic drum. The copy is held against the surface of the copy drum until gripped by means of document retaining guides 38. Pressure guides 39 and document guard 41 retain and guide the trailing edge of the document on the copy drum. After the copy is scanned, it is released from the copy drum to be transported out of the machine by the copy drum and document f,-cd out rollers 42 through document feed out guide 43. Adjacent to the exposure station is a developing station C in which there is positioned a developer apparatus 50 includin.- a developer housing having a lower or sump portion for accumulating developer material 51. Mounted within the developer hotising is a driven bucket-ty_T)o 3,199,866 4 conveyor 52 used to carry the developer material previously supplied to the developer housing to the upper portion of the developer housing from where the develoder material is cascaded over a hopper chute 53 onto the drum. As the developer material cascades over the drum, toner particles of the developer material adhere electrostatically to the previously formed electrostatic latent image areas on the drum to form a visible xerographic 10 powder image; the remainin.- developer material falling off the periph,--ral surface of the drum into the bottom of the developer housing. To-iier particles consumed during the developing operation to form the xerographic powder images are replenished by a ton-.r dispenser 54, 15 mounted within the developer housing. Pos;tioned next adj;acent to the developing station is the iinage transfer station D which includes suitable sheet feedi-ng mechanism adapted to feed sheets of paper successively to the xero.-rapliic drum i-@i coordination with 20 the presentotion of the developed image on the drum at the transfer station. Th-. sheet feeding mechan:@sm include.- a sheet source such as paper tray 60 'Lor a plurality of sheets of a suitable support riiaterial that is, sheets of paper or@ the like, separator rollers 61 adapted to feed 25 the top she,-t oL4 the stack of stipport material through a -uide 67 to a she--t conveyor mechanism 62 having sheet gripper r@iec.ianisms 63 thereon wwch carry the sheet sut)- po-t material inlo contact with the rotating xero.-rapi@ic dum iTi coordination with the appearance of a developed 30 image at the transfer station. The transfer of the xerographic powder image from the drum s,,irface to the support material is effected by means of a corona t@-ansfer device 64 that is located at or immediately after the pol:@it of contact between the support 35 riiateria a t e rotiting xerog c rum. T corona tfansfer device 64 is stibstantia sin-tilar to the coro@ia discharge device that is employed at the charging station i-@i that it also inciiides an array of one or more corona discharge electrodes that are energized from a suitable 40 high potential so,,irce and extend transversely across the drum surface and are substantially enclosed with a shielding memb-,r. In operation, tiie electrostatic field created by the corona transfer device is effective to tack the transfer r-qaterial electrostatically to the drum surface and 45 simultaneously with the tacking action, the e'@ectrostatic f@eld is ef,--ectiv-. to attract the toner particles comprisinthe xerograph-le powd,-r image from the drum surface and cause them to adhere electrostatically to the surface of the support material. 50 As the paper gripper mechanism continues to move forward ip its closed circuit, it will strip the slipport material from the xerographic drt,.m and carry it to a fixing device, such as, for example, heat 'Luser 70, whereat the developed and transferred xerographic powder inia,-e on the support 55 material is perman,-ntly fixed thereto. After fusin,@, tic fnished copy is preferably discharged from the apparatus at a suitable point for collection extemally of the apparatus. To accomplish this, there is provided a pp-ir of delivery rollers 65 and 66 by means 60 of which the copy is delivered from the machine after it is released by the gripper mechanism. Suitable cam means 63 and 4.9 are provid--d at the receiving and delivery stations of the conveyor mechanism, respectively, to actuate the paper grippers of the sheet gripper mech65 anisms at tliese statio-iis to receive or dischar,-e a sheet of suT)Port iraterial. The next and fi..-lal station i-,i the device is a drum cleaning station E whereat any powder remaining on the xero-raphic drum after the transfer step is removed and 70 whereat the xerographic drum is flooded with light to cause dissipation of any residual electrical charge remaining on the xero-raphic drum. To aid in the removal of any residual powder remainin.- on the xerographic drum, there is provided a corona 75 precleanir@g device 84 that is substantially similar to the
[3]3,199,866 ri, corona dischar.-e device that is employed at chara@g station A. Removal of residual powder from the xerographic drum is effected by means of a web cleaner device 80 adapted to continuously feed a clean fibrous web material into wiping contact with the xero-,raphic drum. As shown, the web material 55 is taken from a supply roll 81 and transported around a cleaning or pressure roll 82, preferably made of rubber, onto a take-up or rewind roll 83. Any residual el-.ctrical chan-.e remaining on the xerographic drum is dissipated by li,-Iat from the fluorescent lamp 85 mounted in a suitable bracket above the xero.-raphic drum, a suitable starter and ballast bein.- provided for energizing the fluorescent lamp. Suitable drive means drive the xero.-radhic drum, ',he copy drum, the sheet conveyor mechanism at predetermined sp-.eds relative to each other, and to effect operation of th-- paper separator roll, and the N@ieb cleaner mechanism, the latcer bting driven at a speed or speeds whereby relative movement between the xerographic drum and the web mat.-rial is effected. Suitable drive mcans are also provided for effectin.- operation of the conveyor mechanism and toner disp--nser of the developin.- apparatus assembly. It is believed that the fore-oing description is sufficient for the pi,- rposes of this application to show the .-encral operation of the xerographic reproducing apparatus. For further details concerning the specific construction of the xerographic reproduc-n@ apparatus, refere@ice @s made to copending Eichorn et al. application, Serial No. 162,779, now Patent No. 3,099,943 filed Dece@-nber 28, 1961, and to portions of this specification wherein specific elements cooperating with the sheet feed mechan;sm are illustrated and described although they form no part of the instant invention. Referrin.- now to the slbject matter of the invention, the sheet conveyor mechanism 62 includes two endless belts, in the forr@i of roller chains 321, which extend from a set of dr.:ve sprockets 322 carried by shaft SH3 to, and around, a set of s-orockets 323 oii shaft SH4. These two sets of sprockets are fixedly positioned on their respective shaft to space the roller chains apart from each other by a distance greater than the len.-th of the drum to afford complete use of the xerographic drum surface. In the embodiment of the sheet conveyor mechanism shown, the roller chains carry tnvo sheet gripper mechanisms. The sheet gripper mechanisms 63 are equally spaced from each other alonthe length o'L the chains, and are positioned on the chains at right an.-les to the path of travel of the chains for movement therewith in a circuit between sheet rece,'.Vir.,g and sheet delivery stations, identified as the output area of the paper guide 67, and the delivery rollers 65 and 61@q, respectively. Suitable cam elements 68 and 69 are provided at these stations to actuate the sheet gripper mechanisms. Two paper -.r;-Ppers are used in the -@nachine shown so that as one sheet gripper mechanism is moved from the receiving station carryin@ sheet malerial to the delivery station, the other sheet a.ripper mechanism will advance from the delivery station to the rec-@iving station to be in position to receive the next sheet from paper guide 67. For fi-irth.-r details concerning the specific construction of the sheet feeding mechanism of the x,-ro-raphic reproducing apparatus, reference is made to th,'referenced copending Eichorn et al. appl--cation, Serial No. 162,779. Referrin- now to the subj-.ct matter of the invention, there is shown in FIGURES 3-8, inclusive, a preferred embodiment of the sheet gripper mechanism of the invention. As shown, each sheet @ripper mechanis-@n 63 includes a gripper bar 350 of a length to exteid substantially between the two roller chains 321 to be conn--c'Led thereto by means of clips 354 forming part of the chains Nvhen connected thereto, as is well known in the art. The gripper 6 bar includes a gripper bar bracket 351 and a sheet grippe@r' jaw 355 formed so that the top surface of the gripper bar is positioned tan-,entiary to or slightly below the pitch line of the chains, whereby the gripper bar as it passes beneath the xero.-raphic drum will not jam against the peripheral surface of the xero,-raphic drum. A sheet gripper jaw 355, which may be a separate element fixed to the gripper bar bracket, as shown, or formed integral therewith, extends across the rear of the 10 gripper bar bracket (in terms of the direction of travel of the gripper bar). The sheet gripper jaw 355 is positioned to have surface contact with the leading edge of a sheet of support material as it advanced from the paper guide 67. The sheet gripper jaw cooperates with the 15 tang portions of jaws 362 of the gripp--rs 361 to grip a sh,-et of support material inse.-ted therebetween. Preferably, the sheet gripper jaw 355 is provided at its trailing edge (in terms of the direction of travel), with a concave shape cutout 358 with which the tang portions or jaws 20 362 cooperate to slightly bend the leadin.- edge of a sheet gripped therebetween. Each of the grippers 361 is mounted, by means of pins 371 suitably secured to the pin retaining portions 353 on the leading edge of the -ripper bar bracket, for movement 25 in two directions relative to the fixed sheet gripper jaw 355; that is, for movement from a first position in wmch the tangs or jaws of th.- -ripper are in spaced relation to the sheet grii)per jaw to receive a sheet of support material therebetween, and for movement to a second 30 position in which the tangs or jaws of the gripper are in engagement with the sh,-et gripper jaw or with a sheet of support material sandwiched therebetween. Each -@pper is provided with a depending -,Uide por@ tion or tang 363 terminating in a curved-lip portion 364 35 which is slidably received in sil-itable elongated slots 356 and 352 formed in the sheet gripper jaw and gripper bar braelcet, respectively. The guide portioi or tang 363 serves as a guide or stop for the leading edge of a she.-t and, also as an actuating lever by means of which 40 gripper is actuated. Each gripper is also provided w th a central bent arm or sprin.- tang 373 received in the notched or secured portion 372 of a pin 371. The central bent arm or sprin.- tang of the gripper and the recess 372 in the pin 371 serve a dual function. They accurately 45 restrain and retain the gripper and the pin relationshin to gripper and, this arrangement permits quick and reliable changing of parts. 'fhe tan.- portion or jaw 362 of a or@nper 361 are normally biased into contact with the sheet -ripper jaw 50 355 or with a sheet therebetween by means of a @pring 365. Each sl)ring 365 is formed with a central portion 367, coiled portion 366 on the opposite sides of the central portion and with bent arms 368 at opposite extremities, thereof. Each spring is mounted with its coil,-d por55 tion 366 encircling a pin on opposite sides of the gripper with which it cooperates, the central portion of the spring enga,@ing the curved lip portion 364 of the gripper 361 and with the bent arm portions extendin.- throuah suitable apertures 357 and 353 in the gripper jaw and -iipper 60 bar bracket, respectively, to en.-age the underside of the the gr@Dper bracket. Re.Lerr-ing now to FIG. 1, a sheet of support material, such as paper, forwarded into the paper guide 67 by the action of the separator rollers 61 is buckled as the sepa65 rator rollers continue to advance the sheet after forward motion has been arrested by the -ate of the paper guide. Thus, as a pai)er -ripper advances over the guide, the @ate will be forced open as the paper gr@t)per strikes i-t and, at the same time, the cam follower of the sheet 70 gripper mechanism, that is, the dependin.- guide portion or tan- 363 of each of the sheet grippers will strike the cam assembly 68 secured adjacent to the ge(te of the pap,-r guide. As the cam follower of the sheet -ripper mechanism contacts the cam assembly, the jaws (>f the 75 individual paper grippers will be open to receive the
[4]3,199,866 7 sheet from the paper guide. Because of the slight buckle in the sheet and because at this time the separating rollersare still attemptin- to advance the sheet, the sheet as it unbuckles will be forced betwe,-n the jaws of -the paper .-ripper. As the dependin.- .-uide portion and curved lip 5 portion of the grippers slide off cams 63, the jaws will close by the bias;n,@ action of springs 365 to @rip th-- sheet At the de'@ivery statioj3, the sheet gripper mcchanism passes between the delivery rollers 65 and 66 and as it 10 does so, the grippers are again actuated by means of a cam 69 thereby releasin.- the sheet from the sheet grivner mechanism for discharge from the machine. In operation, the electrostatic field created by the corona transfer device 64 is effective to tack the support 15 material electrostatically to the drum surface, whereby the support material rtioves synchronolsly with the drum while in contact therewith. As the sheet gripper mechanism, carrying the sheet of support material, moves away from the xerographic drum to the delivery station, it pulls 20 the sheet away from the surface of the drum, a@,ainst t.'qe electr@ostatic forces tending to retain the support material to the drum. On a continuous straight line path of travel of the sheet aripper mechanism, the sheet of support material would be uniforiii'iy pulled away from the surface 25 of the drum in a line substantially parallel to the path of travel of the paper gripper and a lineal speed equal to the peripheral speed of the xerographic drum. This, of course, would reqtiire the use of a conveyor having a strai,-ht line run from the drum of a len.-th at least equal 30 to the lengch of the largest sheet of support material to b-- transported by the sheet conveyor mechanism. To reduce th-, overall size of the xerographic apparatus, a conveyor is used in the machin-- which has a strai,@ht run from the drum of a length less than the len@-th of 35 the largest sheet which can be conve@ted by the sheet ,conveyor mechanism. Thus, in the apparatus shown, the trailin- ed-e of a sheet of transfer material co-ald still be in contact with th-- xeragraphi-- drum -vvhile the leading ed@e of the sheet carried by the sheet gripper 40 mechanisni would be at the delivery station of the aPparatus. As shown by the rise position of the cams 69, the sh.-et is carried by a sheet -ripper mechanism which travels between d.-I;very rollers 65 and 66 and partly 45 ,around the sprockets 323 before the sheet, @rippers arQ actuated by the cams to release the rheet. In the apparatus shown, - the position of each -ripper 361 on the aripper bar, and the shape ef each cam 69 to actuate the gripper are such. that the sheet is readily re50 leased to be fed between the delivery rollers. 65 and 66, rather than being fully carried around the axis of delivery roller 65 by the sheet gi-i-oper machani:-:m. The sheet -ripper mechanism is supported on the chains in, a rranner to allow the leadl:nl- ed,,e of th,- sheet .@rj'pper 55 mechanism to be deflected outward as it travels around the sorockets 323 adiacent tc) the cams 69, while the trailing edge ol' the, sheet -ripper mechanism and tlerefore, the leadin.- ed.-e of the sheet ;s maintained on a substantially uniform radius of rotation about-the sproe,@,ets 60 thereby keepin@- the linaal speed-of the paper uniform. The shect- is carried in this path until the @rinpers are opened by cams 69 to release th.- sheet. As the grippers are actuated by the cams 69, to r.-lease the sheet, the jaws of the -ripper are ca=ed upon in an are. The 65 radius of the @rippers is a faster opening radius than the radius of the paper, as it tends to straighten, to prevent re-rippin- a,' the paper as the grippers are gripped a.@ain. As shown in FIG. 1, the I-,adin.- ed.-e of the paper would start to travel in an arc around the sprock10 ets, but as the leadin- ed-e ot the sheet is released by the sheet gripper mechanism, the elasticity of the paper will cause the leading eci,@e of the sheet to snap up into a strai-ht line into the plane of the remainder of th-. 7,5 sheet whereby the paper is dischar- d in a sl-ai- t line ,e @h path from the delivery rollers 65 and 66. It is apparent that a sheet gripper mechanism col@ str-acted in accordance with the inven'Lion can be @'abricated from relatively th;n sheet metal stock material because of the novel configuration of the individual sheet gripper mechanisms and the particular configuration of the sprin- v/hich prevents warping or dis+ortion of the sheet giipper,. the spring actin@- as a stiffener to the cam follower portion of each indivlidual sh,-et gripper. While the invention has been described with reference to the structures disclosed here:ln, it is not confined to the details set forth. It is also appare@it that the term "depending" is used to describe the structure, as shown in t!-@e drawi-il@,,, and this term is not us--rl to limit the de-qii@io.,i oF -,i.-para-' s. This V.-r, @ in1 4catioia is ' tended to cover slich modifications or chan@-@es as may come within the purposes of the improvements or the scope of the following claims. What is
