US3288462A

US3288462A - Apparatus for handling superposed sheets

Info

Publication number: US3288462A
Application number: US400307A
Authority: US
Inventors: Robert H Liva
Original assignee: Xerox Corp
Current assignee: Xerox Corp
Priority date: 1964-09-30
Filing date: 1964-09-30
Publication date: 1966-11-29
Anticipated expiration: 1983-11-29
Also published as: SE358035B; GB1122625A

Description

Nov. 29, 1966 R. H. LWA

APPARATUS FOR HANDLING SUPERPOSED SHEETS Filed Sept. 30, 1964 4 Sheets-Sheet l m I M R W O M M WA T EN y vL A m. H w W m w R Y B Nov. 29, 1966 R. H. LKVA APPARATUS FOR HANDLING SUPERPOSED SHEETS 4 Sheets-Sheet 2 Filed Sept. 30, 1964 INVENTOR ROBERT H.L|VA Q ATTORNEYS Nov. 29, 1966 R. H. LHVA 9 9 APPARATUS FOR HANDLING SUPERPOSED SHEETS Filed Sept. 30, 1964 4 Sheets-Sheet :3

O O O 0 0 0 0 0 l/VVE'IVTOI? ROBERT H. LIVA A 7' Tom/E VS av. 29, 1966 R. H. LWA 3,288,462

APPARATUS FOR HANDLING SUPERPOSED SHEETS Filed Sept. 30, 1964 4 Sheets-Sheet 4 INVEA/TQR ROBERT LIVA ATTORNEYS United States Patent York Filed Sept. 30, 1964, Ser. No. 400,307 3 Claims. (Cl. 271-47) This invention relates in general to a sheet feed mechanism and, in particular, to a multiple sheet detecting device to detect the presence of super-posed sheets advanced by a sheet feed mechanism.

More specifically, the invention relates to an improved multiple sheet detecting device that is particularly adapted for use in a sheet feed mechanism to detect the presence of superposed sheets and thereby actuating a sheet diverting mechanism to divert such super-posed sheets from the normal path of sheet travel.

It is, therefore, the principal object of this invention to improve multiple sheet detecting devices for detecting supenposed sheets advanced by a sheet feed mechanism.

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 drawings, wherein:

FIG. 1 illustrates schematically a preferred embodi ment of a xerographic apparatus having a sheet feed mechanism with a multiple sheet detecting device constructed in accordance with the invention;

FIG. 2 is an enlarged front view of a portion of the sheet feed mechanism and paper transport of FIG. 1, with parts of the sheet feed mechanism broken away to show portions of the paper transport and multi-sheet sensing device;

FIG. 3 is a top view of the paper transport mechanism;

FIG. 4 is a sectional view of the paper transport mechanism taken along lines 44 of FIG. 3;

FIG. 5 is an enlarged view of the multi-sheet sensing device; and

FIG. 6 is a perspective view of the multi-sheet sensing device.

General As shown schematically in FIG. 1, the automatic xerographic reproducing apparatus comprises a xerographic plate 21 including a photoconductive layer or lightreceiving surface on a conductive backing and formed in the shape of a drum, which is mounted on a shaft 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 processing stations.

For the purpose of the present disclosure, the several xerographic processing stations in the path of movement of the drum surface may be described function-ally, as follows:

A charging station, at which a uni-form electrostatic charge is deposited on the photoconductive layer of the xerographic drum;

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

A developing station, at which a xerographic developing 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 powdered image in the configuration of the copy being reproduced;

3,283,462 Patented Nov. 29, 1966 A transfer station, at which the xerographic powder image is electrostatically transferred from the drum surface to a transfer material or support surface; and,

A drum cleaning and discharge station, at which the drum surface is brushed to remove residual toner particles remaining thereon after image transfer, and at which the drum surface is exposed to a relatively bright light source to effect substantially complete discharge of any residual electrostatic charge remaining thereon.

The charging station is preferably located, as indicated by reference character A. As shown, the charging arrangement includes a corona charging device 21 which includes a corona discharge array of one or more corona discharge electrodes that extend transversely across the drum surface and are energized from a 'high potential source and are substantially closed within a shielding member.

Next subsequent thereto in the path of motion of the xerographic drum is an exposure station B. An optical scanning or projection system is provided to project a flowing image onto the surface of the photoconductive drum from a stationary original.

The optical scanning or projection assembly comprises a stationary copyboard which consists of a transparent curved platen member 22 such as, for example, a glass plate or the like, positioned on the exterior of the cabinet, which is adapted to support a document to be reproduced, the document being uniformly illuminated and arranged in light projecting relation to the moving lightreceiwing surface of the xerographic drum. Uniform lighting is provided by banks of lamps LMPS arranged on opposite sides of the copyboard. Scanning of the document on the stationary copyboard is accomplished by means of a mirror assembly which is oscillated relative to the copyboard in timed relation to the movement of the xerographic drum.

The mirror assembly, which includes an object mirror 23, is mounted below the copyholder to reflect an image of the document through a lens 24 onto an image mirror 25 which, in turn, reflects the image onto the xerogra-phic drum through a slot in a fixed light shield 26 positioned adjacent to the xerographic drum surface.

Adjacent to the exposure station is a developing station C in which there is positioned a developer apparatus 30 including a casing or housing having a lower or sump portion for accumulating developer material. A bucket ty-pe conveyor is used to carry the developing material to the upper part of the developer housing where it is cascaded over a hopper chute onto the xerographic drum to effect development. A toner dispenser 35 is used to accurately meter toner to the developing material as toner particles are consumed during the developing operation.

Positioned next and adjacent to the developing station is the image transfer station D which includes a sheet feeding arrangement adapted to feed sheets of support material, such as paper or the like, successively to the xerographic drum in coordination with the presentation of the developed image on the drum surface at the transfer station.

The sheet feeding mechanism includes a sheet feed device 40 adapted by means of vacuum feeders to feed the top sheet, of a stack of sheets on a tray 41, to rollers 42 cooperating with the belts of paper transport 44 for advancing the sheet sufficiently to be held by paper transport 44 which in turn, conveys the sheet to a sheet registration device 45 positioned adjacent to the xerographic drum. The sheet registration device arrests and aligns each individual sheet of material and then in timed relation to the movement of the xerographic drum, advances the sheet material into contact with the xerographic drum in registration with a previously for-med xerographic powder image on the drum.

The transfer of the xerographic powder image from the drum surface to the sheets of support material is effected by means of a corona transfer device 51 that is located at or immediately after the line of contact between the support material and the rotating drum. In operation, the electrostatic field created by the corona transfer device is effective to tack the support material electrostatically to the drum surface, whereby the support material moves synchronously with the drum while in contact therewith. Simultaneously with the tacking action, the electrostatic field is effective to attract the toner particles comprising the xerographic powder image from the drum surface and cause them to adhere electrostatically to the surface of the support material.

Immediately subsequent to the image transfer station, there is positioned a stripping apparatus to paper pick-off mechanism 52 for removing the sheets of support material from the drum surface. This device, which is of the type disclosed in Rutkus et al. United States Patent 3,062,- 536, includes a plurality of small diameter orifices supplied with pressurized aeriform fluid by a suitable pulsator or other device. The pulsator is adapted to froce jets of pressurized aeriform fluid through the outlet orifices into contact with the surface of the xerographic drum slightly in advance of the sheet of support material to strip the leading edge of the sheet from the drum surface and to direct it onto an endless conveyor 55 whereby the sheet material is carried to a fixing device 60. At the fixing device, the transferred xerographic powder image on the sheet of support material is permanently fixed or fused thereto as by heat. After fusing, the reproduction is discharged from the apparatus at a suitable point for collection externally of the apparatus by means of the conveyor 65. In the embodiment shown, the reproductions are discharged from conveyor 65 into a receiving tray 61.

The next and final station in the device is a drum cleaning station E, having positioned therein a corona preclean device 66, a drum cleaning device 70 adapted to remove any powder remaining on the xerographic drum after transfer by means of a rotating brush 71, and a discharge lamp LMP-1 adapted to flood the xerographic drum with light to cause dissipation of any residual elec trical charge remaining on the xerographic drum.

To remove residual powder from the xerographic drum, there is disposed a cylindrical brush 71 rotatably mounted on an axle and driven by a motor, not shown. For collecting powder particles removed from the xerographic drum by the brush, there is provided a dust hood 73 that is formed to encompass approximately two-thirds of the brush area. To ensure thorough cleaning of the brush, a flicking bar 74 is secured to the interior of the dust hood adjacent the edge of the outlet duct 75 of the dust hood and in interfering relation with the ends of the brush bristles whereby dust particles may be dislodged therefrom.

For removing dust particles from the brush and dust hood, an exhaust duct 76 is arranged to cover the outlet of the dust hood, the exhaust duct being connected at its other end to the wall of a filter box 77 attached to the dust hood. A filter bag 78 is secured within the filter box, with the mouth ofthe filter bag in communication with the exhaust duct. Motor fan unit MOT-5 and MOT-6, connected to the filter box, produces a flow of air through the filter box drawing air through the area surrounding the xerographic drum and the dust hood, the air entraining powder particles removed from the drum by the brush as the air flows through the dust hood. Powder particles are separated from the air as it flows through the filter bag so that only clean air reaches the motor unit.

Suitable drive means are provided to drive the drum, rotating mirror and sheet feed mechanism at predetermined speeds relative to each other, and to effect operation of the bucket-type conveyor and toner dispenser mechanism and the other operating mechanisms.

Referring now to the drawings, there is provided a frame for supporting the components of the apparatus formed by a base plate 10 supported on legs 9. Vertical outboard and inboard frame plates 11 and 12, respectively, are secured to base plate 10 in spaced relation to each other.

The xerographic drum 20 is mounted on a horizontal driven shaft and the drum is positioned between frames 11 and 12, with the major xerographic components of the machine mounted around the drum.

It is believed that the foregoing description is sufiicient for the purposes of this application to show the general operation of a xerographic reproducing apparatus using a multiple sheet detecting device constructed in accordance with the invention. For further details concerning the specific construction of the xerographic apparatus shown, reference is made to copending application, Serial No. 400,363, filed concurrently herewith on September 30, 1964, in the name of Robert F. Osborne et al.

Referring now to the subject matter of the invention, sheets separated by the sucker feet 365 of the sheet feed device 40 are advanced by the sucker feet into the bit between the rollers 42 and the belts of paper transport 44. Rollers 42 are idler rollers suitably supported between the

frame plates

301 and 302 of the sheet feed device 40. The

frame plates

301 and 302 are held in spaced relation by cross bar 303, which also supports the multi-sheet sensing device of the invention, and these plates are secured to the base plate 10 of the xerographic apparatus.

Paper transport 44 includes a transport casing 401 closed on top by cover plate 412 and partially closed on the bottom by vacuum shoe 408 to form a vacuum chamber connected by an adaptor 413 to a vacuum conduit and motor MOT-7 operated vacuum pump, not shown. The upper surface of transport casing 401 is provided with front and

rear belt guides

402 and 403, respectively, in relation to the path of paper travel, projecting upward in pairs from the casing surface to guide endless belts 414 which are supported and driven by idler roller and

drive shaft

420 and 417, respectively, journaled in bearing assemblies 405 mounted in transport casing extensions 404. Endless belts 414 are driven by chain 419 engaging sprocket 418 fixed to the end of the drive shaft 417, the chain being driven through a drive system to be described. Transport casing 401 is secured to the

frame plates

301 and 302 of the sheet feed mechanism 40 in a position whereby the belts 414 are in cooperating relation to the idler rollers 42 of the sheet feed mechanism to advance the sheet of transfer material delivered thereto by the vacuum feet 365 of the paper feed mechanism 40.

Idler roller 420 is provided with raised belt support portion 423 for supporting the endless belts 414 and a raised center index portion 422 having a radius equal to or greater than the radius of the belt roller portion plus the maximum thickness of the belt webbing, for a purpose to be hereinafter described. The undercut portion 421, between belt support portions 423, of the idler roller 420 permit the vacuum sucker feet of sheet feed mechanism 40 to advance between the belt support portions to advance sheets into contact between the belts and idler rollers. Multiple parallel rows of apertures 409 are provided in the vacuum shoe 408 in the path of travel of endless belts 414. The belts 414 are provided with suitable apertures 415 whereby as the belts travel over the multiple rows of apertures 409 in the vacuum shoe 408, a sheet will be held to the belts on the underside of the paper transport by the vacuum system and be advanced thereby.

The vacuum shoe 408 is provided with a suitable slot opening 410 for the extension of actuator lever 425 of limit switch 8LS whose purpose is to be hereinafter described. Elongated finger slots 411 are provided in the vacuum shoe 408 between and parallel to the path of travel of the belt 414 to permit extension of reject fingers 426 into the path of travel of sheets in order to eject the sheets from the machine operation.

The reject fingers are secured to reject shaft 427 journaled at its outboard end by bearings 431 positioned in the outboard side of transport casing 401 and in bracket 428, the latter being secured to the inner surface of vacuum shoe 408. The reject fingers are normally biased out of the path of paper travel by torsion spring 429 encircling the reject shaft 427, the spring being secured at one end to the shaft and at its other end to bracket 428.

Movement of the reject fingers 426 into the path of travel of sheets conveyed by endless belts 414 is effected by reject solenoid SOL-3 provided with a lever 432 to contact reject arm 430 secured to the outboard end of reject shaft 427.

To prevent the delivery of multiple or superimposed sheets of transfer material to the xerographic drum, the reject solenoid SOL-3 is energized to project the reject fingers 426 into the sheet path through multi-sheet sensing switch 9L8, the closure of which is effected by a multiple sheet sensing device, generally referred to by reference numeral 433 in FIGS. 5 and 6, having a roller cam follower 439 cooperating with the center index portion 422 of idler roller 420 to sense the presence of multiple sheets.

Roller cam follower 439 is journaled on stub shaft 440 fixed to a follower arm 437. The follower arm is journaled on shaft 435 fixed to the upright ends of base 436 secured to cross bar 303 of the sheet feed mechanism 40 in position to permit the roller cam follower 439 to cooperate with the center index portion 422 of idler roller 420 of paper transport 44. Axial alignment of the follower arm 437 on the shaft is maintained by retaining ring 451 positioned in a suitable groove formed in the shaft.

The follower arm 437 is normally biased in a counterclockwise direction, as seen in FIG. 5, by spring 438 bringing the roller cam follower adjacent the center index portion 422 of the idler roller 420. The spring 438 is secured at one end to base 436 and at its other end to a center extension of the follower arm opposite from the roller cam follower 439. Movement of the follower arm 437 in a clockwise direction is affected by the passage of a sheet or sheets between the roller cam follower and the center index portion 422. Movement of the follower arm in this direction is limited by a boss 436a extending from the base 436 into interference relation with the depending lever 437a of the follower arm, and in the counterclockwise direction by a stop screw 443 threaded into the base 436.

The multi-sheet sensing switch 9L8, a normally open switch, is actuated by actuator arm 434 journaled on shaft 435 between the bifurcated journaled portions of follower arm 437. The actuator arm 434 is normally biased in a clockwise direction by a coil spring 441, as seen in FIG. 5, to actuate switch 9L5 thereby closing its contact.

However, this is normally prevented, except by the passage of multiple-sheets between the roller cam follower 439 and the center index portion 422, by the depending lever 437a of follower arm 437 contacting an extending portion of the actuator arm 434 to rotate this arm in a counterclockwise direction out of contact sutficiently with the actuator of switch 9L8 to prevent closure of its contact.

When multiple sheets are advanced between the roller cam follower and the center index portion, the follower arm 437 and its depending lever are rotated sufiiciently clockwise to permit the spring 441, only, to bias the actuator arm 434 into actuating contact with the actuator of switch 9L8 to close its contact.

Adjustment for the thickness of sheets, to regulate the open and closing action of the actuator arm with the switch 9LS is effected by adjusting screw 444 threaded into the bottom portion of the actuator arm.

As a sheet is fed to the idler roller 420 by the vacuum feet of sheet feed mechanism 40, the sheets pass between the previously described center index portion 422 of the idler roller 420 and the roller cam follower 439 of the sheet sensing device. In the event of multiple or superimposed sheets being fed between these rollers, actuator arm 434 is permitted to rotate sufficiently to close sensing switch 9LS to energize solenoid SOL3 thereby extending the reject fingers into the path of travel of the sheets to eject them into an abort or reject tray 445 located beneath paper transport 44.

While the invention has been described with reference to the structure disclosed herein, it is not to be confined to the specific details set forth or to the specific environment set forth, as, for example, it is apparent that the apparatus may be modified as described above or it may be used in other type devices to effect multiple sheet detection. Other modifications or changes may readily become apparent to those skilled in the art, and, therefore, this application is intended to cover such modifications or changes as may come within the purposes of the improvements of the scope of the following claims.

What is claimed is:

1. A multiple sheet detecting device for use in a sheet feeding mechanism having a conveyor to forward sheets, said multiple sheet detecting device including a base,

a shaft secured to said base,

a follower arm pivotally mounted on said shaft, said follower arm having a lever portion and an arm portion,

a cam follower journaled on said arm portion in position to cooperate with a portion of said conveyor to sense the thickness of sheets forwarded therebetween,

bias means connected to said follower arm to normally bias said cam follower into cooperating relation with said conveyor,

a switch mounted on said base, and

an actuator arm journaled at one end on said shaft, the opposite end being positioned to actuate said switch,

means connected to said actuator arm to normally bias said actuator arm into contact with said switch to actuate said switch, said actuator arm having a portion positioned in interference relation to said lever portion of said follower arm whereby said actuator arm is movably held out of actuating contact with said switch.

2. A sheet transport device including a frame,

a pair of belt shafts journaled on said frame in spaced relation to each other,

endless belts carried by said belt shafts and driven thereby to provide upper and lower runs thereof.

vacuum suction means mounted in said frame and positioned adjacent the lower runs of said belts for holding sheets to the lower surface of the lower runs during transport of the sheets,

a deflecting device mounted in the frame and adapted when actuated to extend between the lower runs of said belts for deflecting the sheets away from the transport device, and

a multiple sheet detecting apparatus operatively associated with said deflecting device and positioned adjacent said belts to sense the feeding of multiple sheets by the belts and produce actuation of said deflecting device in response to the presence of multiple sheets, said multiple sheet detecting apparatus including a base,

a shaft secured to said base,

a follower arm pivotally mounted on said shaft,

said follower arm having a lever portion and an arm portion,

gauge means on said arm portion in position to cooperate with a portion of one belt shaft to sense the thickness of sheets forwarded therebetween,

bias means connected to said follower arm to normally bias said gauge means into cooperating relation with said belt shaft,

a switch,

an actuator arm journaled on said shaft and positioned to actuate said switch, and

means connected to said actuator arm to normally bias said actuator arm into contact with said switch to actuate said switch,

said actuator arm having a portion positioned in interference relation to said lever portion of said follower arm whereby said actuator arm is movably held out of actuating contact with said switch.

3. A superposed sheet detecting device for use in a sheet feeding mechanism having a conveyor to forward sheets, said superposed sheet detecting device including a base,

a shaft secured to said base,

a follower arm pivotally mounted on said shaft,

said follower arm having a lever portion and an arm portion,

gauge means on said arm portion in position to cooperate with a portion of said conveyor to sense the thickness of sheets forwarded therebetween,

bias means connected to said follower arm to normally bias said gauge means into cooperating relation with said conveyor,

a switch,

References Cited by the Examiner UNITED STATES PATENTS 2,312,357 3/1943 Odquist et al.

2,417,145 3/1947 Ward 20988 X 2,822,170 2/1958 Frantz 271-74 X 3,194,554 7/1965 'Hilpman et a1. 271-57 3,227,275 1/1966 Cody 27174 M. HENSON WOOD, JR., Primary Examiner.

ALLEN N. KNOWLES, Assistant Examiner.

Claims

2. A SHEET TRANSPORT DEVICE INCLUDING A FRAME, A PAIR OF BELT SHAFTS JOURNALED ON SAID FRAME IN SPACED RELATION TO EACH OTHER, ENDLESS BELTS CARRIED BY SAID BELT SHAFTS AND DRIVEN THEREBY TO PROVIDE UPPER AND LOWER RUNS THEREOF. VACUUM SUCTION MEANS MOUNTED IN SAID FRAME AND POSITIONED ADJACENT THE LOWER RUNS OF SAID BELTS FOR HOLDING SHEETS TO THE LOWER SURFACE OF THE LOWER RUNS DURING TRANSPORT OF THE SHEETS, A DEFLECTING DEVICE MOUNTED IN THE FRAME AND ADAPTED WHEN ACTUATED TO EXTEND BETWEEN THE LOWER RUNS OF SAID BELTS FOR DEFLECTING THE SHEETS AWAY FROM THE TRANSPORT DEVICE, AND A MULTIPLE SHEET DETECTING APPARATUS OPERATIVELY ASSOCIATED WITH SAID DEFLECTING DEVICE AND POSITIONED ADJACENT SAID BELTS TO SENSE THE FEEDING OF MULTIPLE SHEETS BY THE BELTS AND PRODUCE ACTUATION OF SAID DEFLECTING DEVICE IN RESPONSE TO THE PRESENCE OF MULTIPLE SHEETS, SAID MULTIPLE SHEET DETECTING APPARATUS INCLUDING A BASE, A SHAFT SECURED TO SAID BASE, A FOLLOWER ARM PIVOTALLY MOUNTED ON SAID SHAFT, SAID FOLLOWER ARM HAVING A LEVER PORTION AND AN ARM PORTION, GAUGE MEANS ON SAID ARM PORTION IN POSITION TO COOPERATE WITH A PORTION OF ONE BELT SHAFT TO SENSE THE THICKNESS OF SHEETS FORWARDED THEREBETWEEN, BIAS MEANS CONNECTED TO SAID FOLLOWER ARM TO NORMALLY BIAS SAID GAUGE MEANS INTO COOPERATING RELATION WITH SAID BELT SHAFT, A SWITCH, AN ACTUATOR ARM JOURNALED ON SAID SHAFT AND POSITIONED TO ACTUATE SAID SWITCH, AND MEANS CONNECTED TO SAID ACTUATOR ARM TO NORMALLY BIAS SAID ACTUATOR ARM INTO CONTACT WITH SAID SWITCH TO ACTUATE SAID SWITCH, SAID ACTUATOR ARM HAVING A PORTION POSITIONED IN INTERFERENCE RELATION TO SAID LEVER PORTION OF SAID FOLLOWER ARM WHEREBY SAID ACTUATOR ARM IS MOVABLY HELD OUT OF ACTUATING CONTACT WITH SAID SWITCH.