Document Separator For Accidental Bunching

Abstract

A document handling device is provided with a feed arrangement having a pair of rollers arranged to cooperate in feeding documents of varying size and thickness singly and sequentially from a stack, without adjustment of the device.

Description

BACKGROUND OF THE INVENTION

The present invention relates to sheet feeding devices, and more particularly to apparatus for feeding sheets of varying widths and thicknesses singly from a stack of sheets without adjustment to the feed mechanism and with a minimum wear of the contact surfaces of the feeding device.

In prior art devices employed for feeding sheet material singly from a stack, various combinations of rollers, belts and throating arrangements have been used to insure that double feeding (the feeding of two or more cards) does not occur during operation of a device. In card or sheet feeders which are to be employed in data processing equipment, it is necessary to attain relatively high speeds in the document feeding devices to satisfy the requirements of electronic or optical card readers which operate at speeds compatible with computer operation. It should be evident that a minimum of operator time spent in making adjustments to the feeder would be of major concern when providing a device which is to be acceptable to the industry. Thus, operation of the feeding device at a relatively high document output and the reliability required in the data processing area, serve to impose strict requirements on the design of such a device.

In the past, friction rollers have been combined with oppositely rotating rollers and stationary plates to perform single sheet feeding from a stack. However, in most of these designs, there is a high rate of wear on the moving parts due to continuous frictional contact between one roller and another, or between a feed roller and a stationary member. Many of these prior art arrangements may also prove to be detrimental to the document being fed in that roller slippage and other friction surfaces contracting the document are capable of smearing or erasing information located on the document surface.

Additionally, many of those devices of the prior art, which are intended to feed sheets singly from a stack, employ auxiliary belts, rollers, and fluid pressure means which tend to increase the physical size of the device and increase the cost of the equipment, while decreasing the reliability and efficiency of operation.

The present invention, therefore, has as an object to provide a device for feeding sheets singly and sequentially from a stack which is effective over a wide range of sizes and thicknesses of sheets without requiring external adjustment of the device.

It is a further object of the invention to provide a sheet feeding device of the type described wherein the contact surfaces of the feeding device are subject to a minimum of wear.

Another object of the invention is to provide a device of the type described wherein smearing, erasing or transferring of ink located on the printed surface of the sheets is minimized.

And yet another object of the invention is to provide a sheet feeding device which is less expensive, simpler in operation and more reliable than those of the prior art.

SUMMARY OF THE INVENTION

The aforementioned objects are achieved in the present invention by providing a device for feeding documents singly and sequentially from a stack which has in combination with means for supporting a stack of documents to be sequentially fed from the top of the stack, document feed means adjacent the stack, and means for guiding the top-most document and each successive document sequentially into the feed means. The feed means comprises a first roller means and a second roller means, each having surfaces juxtaposed one with the other, between which a document is guided and by which a document is subsequently fed. Means are provided for driving the first roller such that the juxtaposed surface rotates in a direction to move the document away from the stack when the document is disposed between the rollers and means are provided for driving the second roller to rotate its mating surface in the opposite direction from the first roller. Torque limiting means are connected between the second roller and the second roller driving means. The torque limiting means is adjusted such that the second roller driving means is not effective to rotate the roller when in contact with the first roller means either directly, or with a single document therebetween. The torque limiting means however is effective to rotate the second roller means when two documents are disposed between the surface of the rollers producing a low friction "slip" surface between the documents. A double feed therefore is prevented by the second document being moved back into the stack through rotation of the second roller means by operation of the second roller drive means.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the invention, reference should be made to the accompanying drawing wherein:

FIG. 1 is an elevational view showing a document feeding device having the present invention employed therein;

FIG. 2 is a perspective view, partially in section, showing a fragmentary portion of FIG. 1, in which details of the structure of the document feeder are taken on an enlarged scale for clarity; and

FIG. 3 is a fragmentary elevational view similar to FIG. 1 but taken on the opposite side of the document feeder, showing further details of the device and also taken on an enlarged scale for clarity.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to FIG. 1, there is shown a device for feeding documents singly and sequentially from a stack which comprises a hopper 10 in combination with a feed device 12 and take-away transport 14. The hopper 10, feed device 12 and transport 14 taken together cooperate to remove the top card from a stack and present it to a station (not shown) downstream on the transport, at which work is performed on the document.

The hopper 10 which is shown in the present embodiment, is of a type which is the subject matter of copending U. S. Patent Application Ser. No. 209,808 filed Dec. 20, 1971 by J.A. Peterson which is assigned to the assignee of the present invention. The construction of the hopper 10, as shown, is therefore explained in greater detail in the aforementioned patent application. However, for the purposes of the present invention it should be understood that any arrangement which will feed a stack of documents such that the top-most documents are moved into the feed device 12 could be employed with the present invention, as the invention is not limited to the details of the construction of the hopper itself.

For purposes of the present description, the hopper 10 is shown to include a follower plate 16 inclined at approximately 45.degree. and supported for movement on a belt 17. The plate when driven by belt movement in the direction of the arrows is effective to move a plurality of documents supported thereon toward the feed device 12. Movement of the feed belt 17 is controlled by a switch or sensor 18 to properly position the first document with respect to the feed device 12.

At the opposite side of the feed device 12, the transport 14 is seen to comprise a pair of rollers 19 and 21 into which a document is fed after passing through the feed device. The roller 21, also serves to support a transport belt 22 which is effective to move the document downstream of the arrangement described to a subsequent work station. The transport 14, as shown, is exemplary in nature and is intended to merely indicate one suitable receptacle for single documents which have been fed by the feed device 12. Other such devices for feeding, stacking or arranging the single documents flowing from the feed device 12 may be substituted, without departing from the spirit of the present invention.

Referring now to FIGS. 2 and 3, in these views there are depicted details of the feed device 12, shown in FIG. 1. The feed device 12 is shown to be driven by a motor 23 which may be mounted on suitable structure adjacent the rollers 19 and 21 of the transport 14. The motor 23 drives the feed device 12 by means of a continuous belt 24, and may also be connected to the rollers 19 and 21 to effect operation of the transport 14. In the device shown, the motor 23 is continuously in operation while the document feeder is activated.

It will be noted from FIG. 2 that the major portion of the feed device 12 is mounted in a housing 26 which is pivotable about a pin 27 when the belt 24 is disengaged from the motor 23 to facilitate access to the components of the feed device 12.

The belt 24 is drivingly engaged to a pulley mounted on a shaft 29 which is supported for rotation in suitable bearings in the housing 26. The shaft 29 is connected to a second shaft 31 through a permanent magnet clutch 32.

The shaft 31 is mounted in suitable bearings in the housing 26 and has mounted thereon a pulley 34 in driving engagement with a second drive belt 36. The belt 36 is further engaged with a pulley 37 mounted on a shaft 38, also supported in the housing 26.

A pair of gears A' and B' are mounted on the shaft 38 for rotation thereby, and in meshing engagement with a pair of gears A and B which are mounted for rotation on shafts 39 and 40, respectively. The shaft 39 is rigidly supported by bearings in the housing 26 for rotation, and has a feed roller 41, attached at one end thereof.

It will be noted that the shaft 40 is not supported rigidly in the housing 26 but is mounted for rotation in a pivotable support 42. The shaft 40 has mounted on it a magnetic particle clutch 43 with the gear B mounted on the input hub of the clutch and a separator roller 44 mounted on that portion of the shaft at the opposite side of the magnetic particle clutch. Thus, the rotation of the separator roller 44 and the portion of the shaft 40 on which it is mounted takes place by torque transmitted through the magnetic particle clutch 43, when the gear B is driven.

The support 42 is mounted for pivotable rotation, having one flange provided with an opening for receiving the shaft 38 and the opposite flange being supported by a shaft 46 which is fixed to the housing 26. The shaft 46 is located on the same center line as the shaft 38, and therefore it should be evident that the support 42 is so supported as to pivot about the center line of the shaft 38.

Referring now to FIG. 3, it will be seen that the pivotable support 42 is provided with an angle member forming an arm 47 extending outwardly from the support. A helical spring 48 is disposed with one end attached to the lower portion of the arm 47 and the opposite end attached to a threaded member 49 which is movable in a slot 50 in the housing 26 to adjust the spring tension. Intermediate of the spring 48 and the support 42, a shock absorber 51 having its piston rod 52 attached to the arm 47 is provided. The shock absorber 51 may be of any type known in the art, either adjustable or chosen to produce a stiffness in the range to provide a dampening effect on the system when a document is released and the spring 48 biases the roller 44 into engagement with the roller 41.

For a detailed description of a typical sequence of operation, reference should be had to FIGS. 1, 2 and 3 taken in sequence. As shown in FIG. 1, the hopper 10 is loaded with a plurality of documents which rest at substantially a 45.degree. angle on the follower plate 16 and a portion of the structure (not shown) adjacent the belt 17. With the motor 23 in operation and the clutch 32 disengaged, both the feed roller 41 and the separator roller 44 are inactive. The sensor which is downstream of the feed device 12 is substantially set up to control the spacing between documents and as such, operates to initiate engagement of the clutch 32 and thereby feed a document from the hopper 10.

When the clutch 32 is engaged, the motor 23 is effective through the belts 24 and 36 to rotate the pair of gears A-A' and the feed roller in the direction shown in FIG. 2. Simultaneously, the gear set B-B' is rotated such that the separator roller 44 is rotated in the same direction as the feed roller 41 with the magnetic particle clutch 43 engaged, provided that the rollers 41 and 44 separated.

It should here be noted, that by pivoting the support 42 about the center line of the shaft 38, the roll 44 is movable relative to the roll 41 without disengagement from the drive gears B-B', as the shafts 40 and 38 which retain the drive gears are maintained a fixed distance apart on centers.

It will further be noted that the separator roller 44 is not directly driven by the shaft 40 but is driven through the magnetic particle clutch 43. The magnetic particle clutch 43 is shown as illustrative of an adjustable torque limiting device which restricts the torque at the separator roller 44 to a value less than the torque which is put into the system at the gears B-B'. The device used is a model 97015-012 Fast Step Clutch and Brake Unit, manufactured by Lear Siegler Incorporated and has a rated torque of 15 pound-inch. As is known to one familiar with this type of magnetic power clutch, the application of a voltage to the device causes engagement of the clutch and torque to be applied from the input shaft to the output shaft. When the torque set up by the particular voltage is overcome by the rotated portion of the shaft, the clutch will slip, acting as a drag-type clutch or torque limiting device. As indicated above therefore, with the roller 44 out of contact with the roller 41 (either through slippage between a pair of documents therebetween or by being manually held apart), and the clutch 43 energized, the roller 44 is rotated in the same direction as the roller 41.

Referring to FIG. 3, the rollers 41 and 44 are seen to be forced into engagement by virtue of the spring 48 and its adjustment relative to the arm 47. Thus, the feed roll 41 and the separator roller 44 impart to one another a normal force which is readily adjustable through movement of the fixed end of the spring 48 along the slot 50 of the housing 26. Each of the juxtaposed rollers 41 and 44 is provided with a surface of high friction material to provide a high tangential resistance between the rollers when in contact. The normal force between the rollers 41 and 44 is adjusted such that the torque at the roller 44 provided through the clutch 43 is overcome by rotation of the roller 44 when in contact with the separator roller, or in contact with the separator roller with a single document therebetween. During normal feeding operations, when a single document is introduced between the feed roller 41 and the separator roller 44 (roller 44 being rotated by roller 41 and the clutch 43 slipping) the document is transferred downstream in normal fashion.

However, when a double feed occurs, and two documents enter between the rollers 41 and 44, slippage occurs between the two documents, and the roller 44 no longer has the proper torque applied to it by the roller 41 to overcome the torque produced at the clutch 43. Thus, the shaft 40 takes over, and rotates the roller 44 in an opposite direction to its feeding direction and sends the document back into the hopper 10 from which it is fed on the next feed cycle.

Both the feed roll 41 and the separator roller 44 have high friction materials bonded to their circumferential surfaces. Therefore, when the separator roll 44 is spring loaded against the feed roll 41, the amount of torque transferred to the separator roll in the counter-clockwise direction (as viewed in FIG. 2) is adjusted by varying the spring force such that it is greater than the torque applied in the clockwise direction by the magnetic particle clutch 43. The separator roll 44 now rotates in a counter-clockwise direction, driven by the feed roll 41 due to the friction between the two rolls, creating no relative motion between the two rolls which could cause wear.

From the foregoing, therefore, it should be evident that the present invention provides a device which overcomes objectionable features of prior art feed devices and which operates in a simple manner to provide sequential feeding from a stack of documents.

This normal feed condition exists when the juxtaposed rolls are in contact and there is no document between them and also when there is a single document being driven through. If only a single document is present, the torque may still be transferred through the document due to the fact that the friction between the single document and the rolls is also great enough to overcome the torque applied in the clockwise direction by means of the magnetic particle clutch. However, when two or more documents enter between the rolls, the separator roll immediately reverses in the clockwise direction and feeds the excess document back into the stack until there is only a single document between the rolls which is the proper, or next document. The separator roll then is again driven in the counter-clockwise direction by the mating surface of the feed roll. Thus, there is no relative movement between the rolls or auxiliary rolls, etc., as the above takes place completely and passively due to the lesser amount of friction between two or more sheets of paper or other material of which the documents comprise. As paper to paper or document to document friction is not enough to overcome the torque applied by the magnetic particle clutch, the separator roll rotates clockwise until a multi-sheet feed has been cleared.

No adjustment is necessary to accommodate narrow document thicknesses due to the self-adjusting gap between the rollers, and the spring tension applying the normal force between the rolls need seldom be made after the device is in operation.

Claims

What is claimed

1. In a device for feeding documents singly and sequentially from a stack, feed means comprising a first roller and second roller each having surfaces juxtaposed one with the other for imparting motion to a document placed there between,

a first gear interconnected to said first roller and a second gear interconnected to said second roller,

a drive shaft having one drive gear engaging said first gear and another drive gear engaging said second gear,

said second roller and said second gear being mounted in a housing and said housing being pivotably mounted for rotation about the axis of said drive shaft to bring said juxtaposed surfaces into mating engagement whereby said second gear and said other drive gear are maintained in driving engagement and a fixed distance apart on centerlines during rotation of said housing.

2. The device of claim 1 which further includes torque limiting means connecting said second roller to said second gear.

3. The device of claim 2 which further includes biasing means attached to said housing for urging first and second rollers into mating engagement.

4. The device of claim 3 wherein said torque limiting means is a magnetic particle clutch.

5. The device of claim 1 which further includes means for rotating said drive shaft, and

clutch means interconnecting said drive shaft with said means for rotating said shaft.