Copy Sheet Handling Apparatus For Electrostatic Office Copiers

Abstract

A bellows, incorporated within a sheet feed roller, is actuated by external actuating apparatus to create a partial vacuum at suction ports in the feed roller periphery. A pivotal pressure pad assembly momentarily presses a sheet stack against the ports, leaving the top sheet adhered to the feed roller which is then rotated to advance the separated top sheet to a prefeed position. Additional actuating apparatus, operating on command, rotates the feed roller through the remainder of a complete revolution to feed the prefed sheet from the apparatus and to reorient the feed roller for the next sheet separation and prefeed cycle.

Description

REFERENCE TO RELATED APPLICATION

Reference is hereby made to the commonly assigned, copending Schrempp and Beck application Ser. No. 74,364 entitled Sheet Separation and Pre-Feed Apparatus, filed Sept. 22, 1970, wherein apparatus herein disclosed is claimed.

BACKGROUND AND OBJECTS OF THE INVENTION

The current emphasis in office copier design is speed of operation. Quite naturally, the faster a copier can produce copies the more available it is to subsequent users. Also, a fast copier conserves the time of the operator, who in a small office situation is typically a secretary whose time is valuable. Not only is it important that a copier produce multiple copies rapidly but also that it be capable of producing a single copy without appreciable delay. In a small office situation, probably the most common copy run is that of a single copy.

An additional important design consideration is the size of the copier. With office space so expensive, it is desirable that the copier be reasonably compact. So called "desk copiers" are available, however, when placed on a desk top such copiers take up a considerable portion of the work surface.

One way in which to reduce the copier size is to go to precut copy paper in lieu of roll copy paper which must be withdrawn and cut to the size of the original sheet during each copy cycle. The precut copy sheets are stacked on a tray or the like and must be individually separated from the stack and fed seriatum through the copier. Reliable separation of a single paper sheet from a stack is not an easy task. If a single copy sheet is not successfully separated and fed, the ensuing copy cycle is a complete waste of time. Moreover, if separation and feeding is performed improperly, the copy sheet may jam up somewhere along its feed path. The copier must then be shut off and the jam cleared, which may require a service call.

Another problem with the use of precut copy sheets is synchronizing the sheet separation and feeding functions with the actual copying process repeated during each copy cycle. To achieve requisite synchronization, a "prefeed" technique is typically resorted to. Generally, this involves separating a single sheet from a copy sheet stack and advancing it to a fixed prefeed position at the conclusion of each copy cycle. Thus, when a next copy cycle is called for a copy sheet is already separated from its stack and is fed through the various copy process station, starting from the prefeed position. This simplifies the problem of synchronization and also significantly shortens the time required for single copy runs.

Accordingly, an object of the present invention is to provide improved apparatus for handling precut copy sheets in an electrostatic office copier.

A further object is to provide apparatus of the above character for separating a copy sheet from a sheet stack, feeding the separated copy sheet to a prefeed position, and thereafter, on command, feeding the prefed copy sheet along the initial portion of its feed path through the copier.

Yet another object is to provide apparatus of the above character wherein the various copy sheet handling functions are coordinated and controlled in an efficient and reliable manner.

An additional object is to provide apparatus of the above character which is compact, inexpensive to manufacture, reliable and fast in operation.

Other objects of the invention will in part be obvious and in part appear hereinafter.

The invention accordingly comprises the features of construction, combination of elements, and arrangement of parts which will be exemplified in the construction hereinafter set forth, and the scope of the invention will be indicated in the claims.

SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided a self-contained feed roller structure which is externally actuated to effect separation of the top sheet of paper or the like from a sheet stack and to feed the separated sheet to a reference or prefeed position. The feed roller has incorporated therein a compressible bellows which is in communication with one or more suction ports in the feed roller surface. The bellows, by virtue of its inherent resiliency, normally assumes a distended condition and is compressed by external actuator means. While the bellows is compressed, the paper sheet stack is elevated so as to bring the top most sheet into sealed contacting engagement with the roller surface surrounding the suction ports. The compacting pressure on the bellows is then released, thereby creating a partial vacuum sufficient to hold the top sheet against the feed roller. The sheet stack is then lowered, thereby separating the stack from the top sheet which remains adhered to the feed roller. The feed roller is then rotated through a predetermined angle to advance the separated sheet to a desired prefeed position.

The actuator means includes a first cam which is rotated to compress and release the bellows within the feed roller. A second cam is rotated in coordination with the first cam to effect the raising and lowering of the sheet stack by a pivotal pressure pad assembly in timed relation with the actuation of the bellows. Drive means rotating in synchronism with the first and second cams selectively engages the feed roller to effect the requisite incremental rotation thereof for advancing the separated sheet to the prefeed position. In addition, cam actuated detent means insure that the feed roller is properly angularly oriented at the conclusion of a sheet separation and prefeed operation.

Once the separated sheet has arrived at the prefeed position, it must then be advanced or fed therefrom for processing. In the case of an electrostatic office copier in which the apparatus of the present invention is immenently applicable, the prefed copy paper sheet is advanced through a charging station, an imaging station and a developing station pursuant to reproducing on the copy sheet the image borne by an original document sheet. The suction feed roller also participates in the feeding of a separated sheet beyond its prefed position. Separate drive means are provided for rotating the feed roller through an angle which would return it to its angular orientation at the beginning of a sheet separation and prefeed operation. Incident to this second increment of feed roller rotation, the previously prefed sheet is advanced by the feed roller to a point where it is engaged by secondary feed rollers operating to completely withdraw the sheet from the apparatus of the invention. Cam means operating in synchronism with the second drive means controls the elevational position of the sheet stack in order that advancement of the prefed sheet beyond its prefeed position will not disturb the stack and also controls the detent means so as to insure that the feed roller is properly angularly oriented for the initiation of the next sheet separation and prefeed operation, which preferably occurs at the conclusion of a copy cycle.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawings, in which:

FIG. 1 is a longitudinal sectional view of an electrostatic photocopier employing the apparatus of the present invention;

FIG. 2 is a perspective view of the sheet separation and prefeed apparatus of the invention;

FIG. 3 is a front elevational view, partially broken away, of the apparatus of FIG. 2;

FIG. 4 is a sectional view taken along line 4--4 of FIG. 3;

FIG. 5 is a longitudinal sectional view of the feed roller included in the apparatus of FIG. 2;

FIG. 6 is a side elevational view, partially broken away, of one of the pressure pads incorporated in the apparatus of FIG. 2;

FIG. 7 is a sectional view taken along line 7--7 of FIG. 3 showing the positions of the various parts at the beginning of a sheet separation and prefeed operation;

FIG. 8 is a sectional view taken along line 7--7 of FIG. 3 showing the positions of the various parts upon achievement of separation of the top sheet from the sheet stack;

FIG. 9 is a sectional view taken along line 7--7 of FIG. 3 showing the positions of the various parts after the separated sheet has been advanced to a prefeed position;

FIG. 10 is a sectional view taken along line 10--10 of FIG. 3 showing the detent means incorporated into the apparatus of the present invention;

FIG. 11 is a fragmentary perspective view of the apparatus for advancing a prefed sheet beyond its prefeed position;

FIG. 12 is a side elevational view of the actuating means incorporated in the apparatus of FIG. 11; and

FIG. 13 is an end elevational view of the actuating means of FIG. 12.

Like reference numerals refer to corresponding parts throughout the several views of the drawings.

DETAILED DESCRIPTION

Referring now to the drawings and first to FIG. 1, the apparatus of the present invention is illustrated as being incorporated in an electrostatic photocopier of the direct imaging type which employs copy paper having a photoconductive coating thereon, such as Electrofax paper. It will be appreciated, however, that the apparatus of the present invention has application in other types of office copiers as well as to sheet handling apparatus generally.

As seen in FIG. 1, a stack 10 of precut copy sheets is supported on a tray 12 with the leading edges of the stacked sheets positioned adjacent the sheet-handling apparatus of the present invention, generally indicated at 14. The sheet-handling apparatus 14 includes a sheet separator and sheet feed roller 16 which, in a manner to be described, is employed to separate the top sheet from the copy sheet stack 10 and then advance the separated sheet to a prefeed position where its leading edge is engaged between feed roller 16 and an idler feed roller 18. As will be seen, separation of the top sheet from the sheet stack 10 is effected, in accordance with the invention, by adapting the feed roller 16 with means for creating a partial vacuum at suction ports formed in its peripheral surface. A pressure pad assembly, generally indicated at 20, is actuated to lift the leading edges of the stack 10 so that the upper surface of the top sheet is pressed against the periphery of the feed roller 16 in sealing relation to the suction ports therein. A partial vacuum is then created at these ports to adhere the top sheet to the feed roller periphery which is then readily separated from the rest of the stack 10 merely by pivoting the pressure pad assembly 20 away from the feed roller 16.

Once separation of the top sheet from the sheet stack 10 has been effected, feed roller 16 is then driven through an increment of rotation such that the leading edge of the separated sheet is advanced through the nip of feed roller 16 and idler roller 18 to a prefeed position. The presence of a prefed sheet is sensed by a switch 22.

As contemplated by the present invention, sheet separation and prefeed occurs at the conclusion of each copy cycle. Upon the initiation of the next copy cycle, the prefeed sheet is then advanced to and through the various copy processing stations. Thus, as seen in FIG. 1, a prefed sheet, indicated at 24, is advanced from its prefeed position by rotation of feed roller 16 through a suitable corona charger 26. Rotation of feed roller 16 continues until the leading edge of copy sheet 24 is engaged between a set of feed rollers 28. During advancement of a prefed sheet beyond its prefeed position, the sheet-handling apparatus 14 is controlled by actuating means, generally indicated at 30.

To initiate operation of the actuating means 30, the copier is turned on to provide continuous drive to feed rollers 32 positioned in a document feed path. A document 36 to be copied is inserted into the nip of feed rollers 32 and the passage of its leading edge therebeyond trips a switch 34 which signals the actuating means 30 into operation. A prefed copy sheet 24 is then advanced by rotation of the feed roller 16 through the corona charger 26 and its leading edge arrives at the nip of feed rollers 28 substantially at the same time as does the leading edge of the original document 36 being fed by feed rollers 32. The copy sheet 24 and the original document sheet 36 then pass through an imaging station, generally indicated at 38, where the copy sheet is selectively discharged by light to transform the image borne by the original document to a latent electrostatic image on the surface of copy sheet 24. From the imaging station 38, the juxtaposed document sheet and copy sheet are fed by feed rollers 40 to feed rollers 42 which are also adapted to separate the sheets such that they may thereafter follow separate paths. Immenently suitable juxtaposed sheet feeding and separating apparatus is disclosed in copending application of Beck and Tomasch entitled Separator for Juxtaposed Sheets, Ser. No. 23,215, filed Mar. 27, 1970 and assigned to the assignee of the present application. The copy sheet 24 and the document sheet 36 are selectively acted upon by operation of the separator feed rollers 42 to develop a separation therebetween, such that the document sheet passes over a separator guide plate 43 while the copy sheet passes under the separator guide plate. The document sheet 36 follows a path defined by guide plates 44 for return to the operator. The copy sheet 24 passes over a guide plate 45 to a development station, generally indicated at 46, where the latent electrostatic image carried thereby is developed into a visible image. The developed sheet precedes along a path defined by guide plates 48 for delivery to the operator.

The feed roller 16, as best seen in FIG. 5, consists of an elongated cylinder 50 with a detent disc 52 secured in its left end and an end cap 54 secured in its right end. A partition 56 is secured within cylinder 50 by screws 57. A bellows 58, formed of a suitable material such as metal, is mounted and hermetically sealed at its left end to one side of partition 56. The other end of bellows 58 is sealed off by an end plate 60. Bellows 58 is formed such that it normally assumes an extended condition as indicated in phantom.

A pair of tubular fittings 62 extend through partition 56 and communicate with the interior of bellows 58. A pair of fittings 64 are secured in the wall of cylinder 50 and are coupled to fittings 62 by separate lengths of flexible tubing 66. The fittings 64 thus provide ports 65 at axially aligned points in the periphery of cylinder 50 which are in pneumatic communication with the interior of bellows 58. It will be understood that while two ports 65 are shown in the illustrated embodiment, an additional number of ports may be provided. Also, a single port 65 may be sufficient for effecting sheet separation and prefeed in the manner to be described.

Still referring to FIG. 5, a rubber gripper ring 68, is carried by the feed roller cylinder 50 at the axial location of each port 65. In the vicinity of each fitting 64, the material of gripper ring 68 is removed and an insert 70 is substituted. Rubber gripper rings 68 are formed of a suitable durometer rubber or other elastomeric material for proper sheet feeding coaction with idler roller 18 (FIG. 1). Insert 70 is preferably of a softer resilient material than gripper ring 68 so that, in the manner to be described, the top sheet of the sheet stack 10 is adequately sealed against the material surrounding the ports 65 by operation of the pressure pad assembly 20 (FIG. 1) at the time a negative pressure or suction is created at the ports 65 by operation of the bellows 58. It will be appreciated that certain elastomeric materials may be conducive to both functions, thus eliminating the need for inserts 70.

Still referring to FIG. 5, the inserts 70 are apertured so as to communicate with the ports 65 provided by fittings 64 and is also recessed to provide a suction cuplike shape for improved adherence of a paper sheet thereto upon actuation of the bellows 58.

As seen in FIGS. 3 and 5, a coaxial stub shaft 74, secured to detent disc 52, serves to mount the left end of feed roller 16; the shaft being journaled in an upright side frame 76 secured to a base 77. The other end of feed roller 16 is rotatably mounted by a sleeve 78 secured in a central bore through end cap 54 and journaled by a bushing 80 mounted by side frame member 82, also secured to base 77 (FIG. 3). An elongated actuating pin 84 extends through sleeve 78 with its left end fastened to end plate 60 of bellows 58. Actuating pin 84 carries an integral cam follower disc 86 at a point beyond bushing 80; the cam follower disc being acted upon by a sheet separation and prefeed actuating mechanism to be described.

As previously noted, the bellows 58 is constructed such that its normal unconstrained condition is that indicated in phantom in FIG. 5. When the bellows 58 is so extended, pin 84 and cam follower disc 86 are pushed to the right, assuming the phantom position shown in FIG. 5. When the cam follower disc 86 is pushed to the left, pin 84 acts to compress the bellows 58. At this point, as will be seen, the top sheet of the stack 10 is brought into sealing engagement about ports 65, whereupon the bellows is released to assume its extended position. This is effective to create a negative pressure or suction at ports 65 sufficient to securely hold the paper sheet thereto.

Turning now to FIG. 2, the sheet separation and prefeed-actuating mechanism is generally indicated at 88. Mechanism 88 is powered from a drive train consisting, in part, of gears 89 and 90, shaft 91 and gears 92 and 93 (FIG. 3) which are all driven as long as the copier is turned on. A shaft 96 for gear 93 constitutes the input shaft to a one revolution clutch 98 which is engaged by actuation of a solenoid 100. Thus, each time the solenoid 100 is actuated, it causes the clutch 98 to couple its input shaft 96 to its output shaft 102 for one complete revolution, after which the two shafts are decoupled. Output shaft 102 carries a radial disc cam 104, a helical cam 106 and a disc 108 having a spur gear segment 110 formed in its periphery and an internal annular cam track 112 with a raised cam segment 114 formed therein. It is thus seen that upon engagement of clutch 98, cam 104, cam 106 and disc 108 are driven through one complete revolution.

As seen in FIGS. 2 and 3, radial disc cam 104 acts on a cam follower 116a carried by a cam follower arm 116 which is secured at its lower end on a shaft 118 rotatably mounted by brackets 119 (FIG. 3). A hook-shaped actuator 120, secured on the left end of shaft 118, acts on an actuator pin 122 to downwardly pivot a carriage 124, included in the pressure pad assembly 20 (FIG. 1). Carriage 124 is pivotally mounted on a fixed shaft 126, seen in FIGS. 1 and 11. A spring 128 biases cam follower 116a against the periphery of radial disc cam 104.

Still referring principally to FIGS. 2 and 3, the carriage 124 supports a pair of brackets 130, secured thereto by bolts 131. The upper end of each bracket 130 is bent laterally outward so as to support a pressure pad 132. As seen in FIG. 6, each pressure pad, which is formed of a suitable material such as metal, has a threaded shaft 132a which extends through a hole in the lateral portion of bracket 130 and receives a nut 133 clamping the pressure pad thereto. The face of each pressure pad is formed on a radius corresponding to the radius of curvature of the gripper rings 68 (Fig. 2). A recess 132b is formed in the front surface of the pressure pads so as to leave a rim 132c which acts as the pressure transmitting surface for pressing the top sheet of the sheet stack 10 against the surface of insert 70 surrounding ports 65 (FIG. 5). As is seen in FIGS. 1 and 7 through 9, the leading edges of the sheet stack 10 lie in the area between feed roller 16 and the pressure pads 132. The carriage 124 is normally urged toward the feed roller 16 by springs 136 (FIG. 3). Thus, the pressure pads 132 engage the undersurface of the bottom sheet of the sheet stack and lift the leading ends of the stacked sheets upwardly to bring the upper surface of the top sheet adjacent its leading edge into sealing engagement about the ports 65.

As is seen in FIG. 2, the carriage 124 carries lateral extensions which are bent upwardly and extend toward the feed roller and curve downwardly to provide outrigger elements 138 which act to support the lateral edge portions of the sheet stack as the leading edge portions therefore are lifted upwardly toward the feed roller 16 by clockwise pivotal movement of the carriage 124. Outrigger elements 138 also serve as supports for stop elements 140 which extend upwardly in abutting engagement with the leading edges of the sheet stack 10. These stop elements 140 serve to prevent forward movement of the underlying sheets in the sheet stack as the separated top sheet is advanced to its prefeed position and beyond by rotation of the feed roller 16.

Still referring principally to FIGS. 2 and 3, the helical cam 106 carried on shaft 102 acts on the cam follower disc 86 which was described in connection with FIG. 5. In the positions of the various parts shown in FIG. 2, which are their positions at the beginning of each sheet separation and prefeed operation, the trailing end 106a of helical cam 106, assuming counterclockwise rotation thereof, engages the cam follower disc 86 thereby compressing bellows 58 through actuating rod 84. This initial condition is also seen in FIG. 4. After the helical cam 106 is rotated through a small increment of counterclockwise rotation, cam follower 86 is released, permitting the bellows 58 to extend, thereby creating a suction at ports 65. It is seen that as helical cam 106 continues to rotate, the leading, laterally offset end 106b of the cam engages the cam follower disc 86 to cause the bellows 58 to be gradually compressed to the state shown in FIG. 5.

As is seen in FIG. 2, at the beginning of a sheet separation and prefeed operation and before the bellows 58 is released by helical cam 106, cam follower 116a is riding in the valley 104a of radial disc cam 104. Actuator 120 is thus located and held in its extreme clockwise position by spring 128, thereby permitting the carriage 124 to be positioned by spring 136 adjacent the feed roller 16 and press the top sheet of the stack 10 into sealing relation with the ports 65. The actuator 120 is oriented on its shaft 118 such that the pressure pads 132 are always capable of pressing the top sheet against the ports 65 regardless of the number of sheets in the sheet stack 10. As cams 104 and 106 begin to rotate, the first thing that happens is that the cam 106 releases the bellows 58 which then creates the suction at ports 65. The suction or negative pressure at ports 65 is effective to hold the top sheet which is pressed thereagainst by the pressure pads 132 acting through the underlying sheets in the sheet stack. As the radial disc cam 104 continues to rotate, cam follower 116a rides out of valley 104a, thereby causing cam follower arm 116 to rock counterclockwise bringing actuator 120 into depressing engagement with the actuator rod 122. The carriage 124 is then rocked in the counterclockwise direction dropping the leading edges of the underlying sheets in the sheet stack 10 away from the feed roller 16. The top sheet thus becomes separated from the remainder of the stack by virtue of the suction created at ports 65.

Having separated the top sheet from the sheet stack, it remains to advance the separated sheet to a prefeed position. Prefeed is accomplished by rotation of the feed roller by engagement with the gear segment 110 formed on the periphery of disc 108 rotating with cams 104 and 106 on shaft 102. Rather than have mating gear teeth formed on the feed roller 16, it is preferred to provide a ring 150 of rubber or other suitable elastomeric material secured to end cap 54 (FIG. 5) which is engaged by the gear segment 110.

As the disc 108 rotates counterclockwise, a cam follower 152 carried by a cam follower arm 154 is rocked downwardly by cam segment 114. The other end of cam follower arm 154 is secured on an elongated shaft 156 which is appropriately mounted by means not shown. The other end of shaft 156 carries a detent release arm 158 which supports at its free end a pawl 160 adapted to operate against detent disc 52 secured to the left end of feed roller 16. The detent disc 52, as best seen in FIG. 10, is formed having a pair of radial walls 52a and 52b.

Returning to FIG. 2 it is seen that as disc 108 rotates counterclockwise, cam follower arm 154 disengages the pawl 160 from the radial wall 52a of detent disc 52. This frees the feed roller 16 for clockwise rotation as the gear segment teeth 110 bite into the ring 150. Before the last tooth of gear segment 110 rotates out of driving engagement with the ring 150, cam segment 114 terminates, thereby permitting the pawl 160 to rise back into engagement with the periphery of detent disc 52 before it encounters radial wall 52b; this movement being induced by return spring 162. As radial wall 52b encounters pawl 160 to terminate further rotation of feed roller 116, the last tooth of gear segment 110 still drivingly engages rubber ring 150. This insures that the feed roller 16 is angularly oriented at the termination of the prefeed operation precisely at the point where radial wall 52b is engaged by pawl 160. It is for this reason that an elastomeric ring 150 is preferred over a gear ring as it would require stringent manufacturing tolerances to insure that the gears disengage precisely at the point where the pawl 160 engages the radial wall 52b of detent disc 52. It will be appreciated if the drive of feed roller 16 terminates short of the detent position determined by radial wall 52b, the separated sheet will not be prefed to the desired prefeed position. On the other hand, if the drive terminates after the tip 160 engages radial wall 52b, an interference situation is created which would result in damage to various parts of the apparatus. Rubber ring 150, however, yields to release the last gear tooth of segment 110 as the pawl 160 inhibits further feed roller rotation. This slippage insures proper angular orientation of the feed roller at the conclusion of the prefeed operation.

The positions of the various parts of the sheet handling apparatus 14 at various stages in the sheet separation and prefeed operation are shown in FIGS. 7 through 9. In FIG. 7 the parts are shown in their positions at the beginning of a sheet separation and prefeed operating cycle, which positions are also illustrated in the perspective view of FIG. 2. Thus, the pressure pads 132 are pressing the leading edge portions of the sheet stack 10 against the feed roller 16 under the force of the carriage springs 136 (FIG. 3). Solenoid 100 is pulsed and the one revolution clutch 98 is engaged to rotate its output shaft 102 through a complete revolution. The first event is the creation of a suction at each of the feed roller ports 65 caused by the disengagement of the helical cam trailing edge 106a from the cam follower disc 86. As previously noted, the bellows 58 springs to its extended condition; the resulting internal expansion of the bellows being effective to create the suction or negative pressure at ports 65. Thereafter, radial disc cam 104 operates through cam follower arm 116 and actuator 120 to pivot the carriage 124 downwardly to remove the underlying sheets of the stack from the feed roller 16. The top sheet 10a, however, is held against the feed roller ports 65 by the suction thereat. This condition is shown in FIG. 8.

Also at this time, the cam segment 114 carried by disc 108 acts through cam follower arm 154 and detent release arm 158 to remove pawl 160 from engagement with the radial wall 52a of detent disc 52. The feed roller is thus free to be rotated by gear segment 110 in the clockwise direction through an angle A (FIG. 10) of approximately 100.degree.. As seen in FIG. 9, the separated top sheet 10a of the sheet stack 10 has been advanced through the nip of idler roller 18 and the gripper rings 68 on feed roller 16 to a prefeed position. During prefeed of the top sheet 10a, stop elements 140 prevent the underlying sheets of the stack from being dragged forward by prefeeding movement of top sheet 10a. Switch 22 is actuated by the top sheet as it is advanced to the prefeed position and thus senses that a sheet has been successfully prefed.

As the clutch output shaft 102 continues to rotate through the remainder of its complete revolution, helical cam 106 reengages cam follower disc 86 with its leading edge 106b to gradually compress bellows 58. This action does not disturb the prefed top sheet 10a since it is engaged in the nip of feed roller 16 and idler roller 18. As radial disc cam 104 continues to rotate through to the conclusion of its complete revolution, cam follower 116a again rides into valley 104a, whereupon the carriage springs 136 pivot the carriage 124 in the clockwise direction bringing the pressure pads 132 upwardly to press the underlying sheets of the sheet stack against the feed roller 16. Thus, the carriage 124 assumes the position shown in FIG. 7, while the feed roller 16 remains in the orientation shown in FIG. 9.

Having successfully prefed a top sheet 10a, it now remains to advance the prefed sheet on through the copier process stations and also to return the feed roller 16 to its proper angular orientation for the beginning of another sheet separation and prefeed operation. To this end, the actuating means 30 mentioned in connection with FIG. 1 and illustrated in detail in FIGS. 11 through 13 is uniquely adapted. As best seen in FIG. 13, the actuating means 30 includes a drive pulley 170 which is continuously rotated by a drive belt 172 for as long as the copier is turned on. Pulley 170 is mounted on a shaft 174 which serves as the input shaft to a one revolution clutch 176. The clutch output shaft 178 is adapted to rotate a radial disc cam 180, a disc 182 and a second radial disc cam 184. As seen in FIG. 13, a solenoid 186 is pulsed to pull down on a link 188 which is connected to the free end of a pivotally mounted arm 190. A spring 192 (FIG. 12) normally urges the arm 190 upwardly to engage a stop 190a against a ledge 194a formed in the periphery of a detent plate 194. It is thus seen that when solenoid 186 is pulsed, the free end of arm 190 is pulled downwardly to release the detent plate 194, thereby permitting the output shaft 178 to rotate in the counterclockwise direction as seen in FIG. 12 through a complete revolution, as driven by a clutch input shaft 174. At the completion of a revolution, detent ledge 194a again encounters the stop 190a in arm 190 to inhibit further counterclockwise rotation.

As seen in FIGS. 11 and 12, radial disc cam 180 acts on a cam follower 200 carried by a cam follower arm 202 which is secured at its other end on a shaft 204. The other end of shaft 204 carries a sector gear 206 which engages a spur gear 208 carried on a shaft 210 supported by a U-shaped bracket 212. The other end of shaft 210 carries an actuator arm 214 which is oriented in actuating relation to an actuator pin 216 carried by carriage 124. Cam follower 200 is urged against the periphery of radial disc cam 180 by a return spring 218 acting on a return spring arm 220 secured on shaft 204.

It is thus seen that when radial disc cam 180 is rotated in the counterclockwise direction, cam follower arm 202 is rocked downwardly as the cam follower 200 rides up on the rise 180a. This results in clockwise rotation of actuator arm 214 and downward pivotal movement of carriage 124 to remove the pressure pads 132 from the vicinity of the feed roller 16. It will be recalled that the orientation of the radial disc cam 104 in FIG. 2 at the conclusion of a prefeed operation is such that the pressure pads are permitted to press the leading edges of the sheet stack against the feed roller periphery. Thus, as the prefed sheet is advanced beyond its prefeed position, the pressure pads 132 must again be removed from the periphery of the feed roller so as not to interfere with the feeding of the prefed sheet. Radial disc cam 180 serves this purpose.

Returning to FIGS. 11 and 12, radial disc cam 184 acts on a cam follower 224 carried by a cam follower arm 226 which is urged in the counterclockwise direction by return spring 227. Cam follower arm 226 is pivotally mounted on a shaft 228 and carries a pin 230 which is received in an elongated slot 232 formed in the free end of detent release arm 158. This lost motion connection permits the pawl 160 to be released from detent disc 52 by rotation of disc 108 (FIG. 2) or radial disc cam 184. Thus, to advance a prefed sheet 10a beyond its prefeed position, cam follower 224 rides up on cam rise 184a upon rotation of radial disc cam 184 to free pawl 160 from radial wall 52b. Cam rise 184a terminates at 184b and the pawl is permitted to assume a position in intercepting relation to radial wall 52a as feed roller 16 is rotated in the clockwise direction.

To drivingly rotate feed roller 16, a spur gear 240 is secured on shaft 74 extending from the left end of the feed roller. As disc 182 is rotated through a complete revolution, gear segment teeth 182a formed in the periphery thereof engage spur gear 240, thus imparting clockwise rotation to feed roller 16. From FIG. 1 it is seen that such rotation advances a prefed sheet through corona charger 26 to the nip of feed rollers 28. The length of gear segment 182a is such that feed roller 16 is rotated through slightly less than an angle B (FIG. 10) which, when added to angle A, constitutes a complete revolution of the feed roller necessary to reorient it to its angular position at the beginning of a sheet separation and prefeed operation. This angular position is determined by the engagement of pawl 160 with radial wall 52a of detent disc 52.

To avoid an interference situation, gear segment 182a disengages from spur gear 240 before the feed roller 16 has been rotated completely through angle B. The final increment of feed roller rotation to bring radial wall 52a of detent disc 52 into abutting engagement with pawl 160 is induced by a column spring 244 which is secured to a face of spur gear 208 as best seen in FIG. 11. The free end of column spring 244 moves upwardly into engagement with a ledge 246 formed on the periphery of detent disc 52 as cam follower 200 rides off the termination 180b of cam rise 180a formed in radial disc cam 180 near the conclusion of a complete rotation thereof. Column spring 244 acts against ledge 246 to rotate feed roller 16 through a very small angle to the point where pawl 160 engages radial wall 52a, thereby finally positioning the feed roller for the next sheet separation and prefeed operation.

It will be noted particularly from FIG. 12, that the prefed sheet feeding rotation of the feed roller 16 occurs within the first approximately 60.degree. of rotation of the gear segment disc 182. As seen from FIG. 1, the sheets being separated, prefed and then fed are significantly longer in length than the circumference of feed roller 16, thus a complete revolution of the feed roller is not sufficient to clear the top sheet 10a from the sheet-handling apparatus 14. A complete feed roller revolution is sufficient however to advance a copy sheet from its position on the sheet stack 10 to the nip of feed rollers 28. At this point, feed rollers 28, in effect, act to pull the top sheet without further rotation of feed roller 16 as the sheet is cleared from the sheet-handling apparatus 14. In order to facilitate this operation, a Teflon pad 250 (FIG. 2) is embedded in each gripper ring 68 carried by feed roller 16. The Teflon pads 250 are positioned such that they are aligned with idler feed roller 18 when the feed roller 16 is oriented for the beginning of a sheet separation and prefeed operation which is also its orientation during the time that a prefed sheet is being cleared from the sheet-handling apparatus 14 by feed rollers 28. The Teflon pads 250 thus provide a relatively frictionless surface over which the sheets may be dragged, and thus damage to the sheet is avoided.

An additional function of radial disc cam 184 is to actuate a switch 252 seen in FIGS. 11 and 12. Switch 252 has a switch-actuating arm 254 which is actuated by the raised cam surface 184a of radial disc cam 184. This switch serves as an interlock switch which is used to enable the actuation of solenoid 100 to initiate a sheet separation and a prefeed operation. While the actuating arm 254 of switch 252 bears against the lower cam surface 184c of radial disc cam 184, solenoid 100 is disabled and a sheet separation and prefeed operation cannot be initiated.

From the foregoing description, it is seen that the operating sequence, in summary, is as follows. Assuming a separated sheet has been prefed to the prefeed position, preparatory to the next copy cycle, the copier is turned on and on original document 36 is inserted into the nip of feed rollers 32 (FIG. 1). Switch 34 is triggered by the passage of the leading edge of the document beyond feed rollers 32 and, as a result, solenoid 186 (FIG. 13) is energized to engage one revolution clutch 176. The prefed sheet 10a, which is in the position shown in FIG. 9, is then fed by rotation of feed roller 16 through the corona charger 26 and into the nip of feed rollers 28, arriving there at the same time as does the leading edge of document sheet 36. The feed roller 16 remains in the orientation shown in FIGS. 1 and 7, while the sheet 10a is cleared from the sheet handling area by the feed rollers 28. Near the completion of the full 360.degree. rotation of radial disc cam 184, the actuating arm 254 of switch 252 rides up on the raised cam surface 184a thereof. This occurs just after the time that the sheet 10a has cleared the area of the sheet-handling apparatus 14 and the resulting actuation of switch 252 triggers the solenoid 100 to initiate a sheet separation and prefeed operation. Preferably, switch 22 is connected in series with switch 252 so that solenoid 100 cannot be triggered by switch 252 if a prefed sheet 10a has not cleared the sheet handling apparatus. As previously described, the sheet separation and prefeed actuating means 88 then operates to separate and advance a top sheet 10a from the sheet stack 10 and advance it to the prefeed position shown in FIG. 9.

Switch 22 senses whether or not a sheet is in the prefeed position preparatory the initiation of the next copy cycle. If when the copier is turned on and switch 22 senses that no sheet is in the prefeed position, such as would occur after the copy paper supply has been exhausted and the stack 10 is replenished, the control logic may be designed such that switch 22 initiates a succession of sheet separation and prefeed operations until a sheet 10a is successfully separated and prefed. It will be observed that whatever the initial orientation of feed roller 16, it will be indexed through an increment equal to angle A (FIG. 10) each time the sheet separation and prefeed actuating mechanism 88 is triggered by solenoid 100. During one of these indexing steps, pawl 160 engages radial wall 52a to stop the feed roller 16 at the proper orientation for the initiation of a sheet separation and prefeed operation. This is permitted since gear segment 110 will slip on ring 150 after feed roller rotation has been inhibited by pawl 160. With the next pulsing of solenoid 100, a top sheet 10a is separated and prefed, whereupon switch 22 is tripped and the copier is then prepared for a normal copy cycle.

It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained and, since certain changes may be made in the above construction without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Claims

Having described the invention, what is claimed as new and desire to secure by Letters Patent is:

1. Copy-sheet-handling apparatus for electrostatic copiers, said apparatus comprising, in combination:

A. a tray for supporting a stack of precut copy sheets;

B. a roller mounted for rotation, said roller including:

1. means for retaining a copy sheet against the periphery of said roller;

2. first and second drive-engagable means;

C. a carriage supporting the leading edge portions of the stacked sheets, said carriage

1. adapted for movement from a first position remote from said roller to a second position adjacent said roller to lift the stack and press a surface portion of the top sheet thereof against said retaining means;

D. sheet separation and prefeed control means operating in sequence during each operating cycle to

1. position said carriage to its second position,

2. actuate said retaining means to retain the top sheet against the periphery of said roller,

3. position said carriage to its first position to remove and separate the underlying sheets from the top sheet of the stack, and

4. engage said first drive-engagable means to rotate said roller through a first predetermined increment of rotation and thereby advance the separated top sheet to a prefeed position,

E. a pair of feed rollers stationed in the copy sheet feed beyond said prefeed position; and

F. copy cycle feed control means operating upon the initiation of a copy cycle to engage said second drive-engagable means and rotate said roller through a second increment of rotation to feed a prefed copy sheet from said prefeed position to the nip of said feed roller pair.

2. The apparatus defined in claim 1, wherein said first and second increments of roller rotation total 360.degree..

3. The apparatus defined in claim 2, wherein said roller further includes detent means and said sheet separation and prefeed control means and said copy cycle feed control means act on said detent means to precisely define said first and second increments of roller rotation.

4. The apparatus defined in claim 1, which further includes an idler roller positioned to coact with said roller to feed a copy sheet beyond said prefeed position.

5. The apparatus defined in claim 4, wherein the length of a copy sheet exceeds the circumference of said roller, and said roller includes a low friction surface segment angularly positioned to be juxtaposed to said idler roller when said roller concludes said second increment of rotation, whereby the trailing portion of the copy sheet may be drawn through the nip of said roller and said idler roller by said feed roller pair without rotating said roller.

6. The apparatus defined in claim 1, wherein the operating cycle of said sheet separation and prefeed control means is initiated during the concluding portion of the operating cycle of said copy cycle feed control means, said latter means including signal means for initiating an operating cycle of said sheet separation and prefeed control means.

7. The apparatus defined in claim 1, wherein

1. said sheet separation and prefeed control means includes:

a. a first shaft adapted to execute a complete revolution to define an operating cycle thereof,

b. a first cam on said first shaft adapted to position said carriage to its first and second positions,

c. a second cam on said first shaft adapted to actuate said retaining means, and

d. a first segment gear on said first shaft engaging said first drive-engagable means, and

2. said copy cycle control means includes:

a. a second shaft adapted to execute a complete revolution to define an operating cycle thereof,

b. a third cam on said second shaft adapted to position said carriage to its first and second positions,

c. a second segment gear on said second shaft engaging said second drive-engagable means,

d. signal means for initiating an operating cycle of said sheet separation and prefeed control means, and

e. a fourth cam on said second shaft adapted to actuate said signal means during the concluding portion of the operating cycle of said copy cycle feed control means.

8. The apparatus defined in claim 7, wherein said roller carries a detent disc having first and second detents for defining first and second angular detent positions for said roller, said apparatus further including:

A. a pawl carried by a detent release arm, said detent release arm

1. being actuated by said sheet separation and prefeed control means to disengage said pawl from said first detent and release said roller for rotation from said first detent position through said first increment of rotation to said second detent position where said pawl engages said second detent, and

2. being actuated by said copy cycle feed control means to disengage said pawl from said second detent and release said roller for rotation from said second detent position through said second increment of rotation to said first detent position where said pawl engages said first detent.

9. The apparatus defined in claim 7, wherein said second segment gear disengages said second drive-engagable means before said roller reaches said first detent position and said copy cycle feed control means further includes resilient means engaging said detent disc to rotate said roller to said first detent position.

10. The apparatus defined in claim 1, wherein said carriage includes a stop element engaging the leading edges of the underlying sheets of the stack during feeding of the separated top sheet.

11. The apparatus defined in claim 1, wherein said retaining means comprises negative pressure-generating means self-contained within said roller for creating a suction at ports formed in the periphery of said roller.

12. The apparatus defined in claim 1, which further includes sensing means for detecting the presence of a sheet in the prefeed position.

13. Copy-sheet-handling apparatus for electrostatic copiers, said apparatus comprising, in combination:

A. a roller mounted for rotation, said roller including:

1. self-contained suction-generating means for creating a suction force at a port formed in the peripheral surface thereof, and

2. first and second drive-engagable means;

B. a tray for supporting a stack of precut copy sheets;

C. a carriage movable toward and away from said roller and carrying a pressure pad aligned with said port for lifting the stack to press a surface portion of the top sheet into sealing relation with said port;

D. sheet separation and prefeed control means operating said carriage and said suction generating means to retain the top sheet against said roller as said carriage is moved away from said roller to separate the top sheet from the sheet stack and engaging said first drive-engagable means to rotate said roller through a first predetermined increment of rotation and thereby advance the separated top sheet to a prefeed position;

E. copy cycle feed control means operating upon the initiation of a copy cycle to engage said second drive-engagable means and rotate said roller through a second increment of rotation to feed a prefed copy sheet beyond its prefeed position; and

F. a pair of feed rollers engaging the leading edge of the prefed copy sheet shortly before the conclusion of said second increment of roller rotation.

14. The apparatus defined in claim 13, wherein said roller carries detent means acted upon by said sheet separation and prefeed control means and said copy cycle feed control means to define said first and second increments of roller rotation, said first and second increments of roller rotation totaling 360.degree..

15. The apparatus defined in claim 13, wherein said suction-generating means comprises a bellows, said sheet separation and prefeed control means acting on said bellows during the operating cycle thereof to expand and compress said bellows to create said suction force.

16. The apparatus defined in claim 14, wherein said roller carries a resilient ring for coaction with an idler roller to feed a separated top sheet, said port opening at the periphery of said ring, the length of a copy sheet exceeding the circumference of said roller, a low-friction surface segment imbedded in said ring at an angular position to be juxtaposed with said idler roller when said roller concludes said second increment of rotation, whereby the trailing portion of the copy sheet may be readily drawn through the nip of said ring and said idler roller by said feed roller pair without rotation of said roller.

17. The apparatus defined in claim 16, wherein said copy cycle feed control means further includes signal means actuated during the concluding portion of the operating cycle thereof and after a copy sheet has been drawn completely through the nip of said roller ring and said idler roller to initiate an operating cycle of said sheet separation and prefeed control means.