Document feeder apparatus

Abstract: An apparatus (12) for feeding documents from a stack (20) of documents, in single file, to a document track (16) is provided in which velocity sensor (116) detects the speed at which a document pusher (14-3) moves the stack of documents towards a document picking station so that if the movement is too fast, document picking means at the picking station is disabled until a time has elapsed to permit stabilization of pressure on the first document (20-1) to be picked from the stack (20) at the picking station.

Description: The present invention relates to document feeder apparatus, according to the preamble of claim 1. Such a document feeder apparatus is disclosed in DE-C-3 706 810. The purpose of document feeder apparatus is to separate or pick documents from a stack of documents in a hopper and feed them at a particular rate with an inter-document gap therebetween to a downstream module such as a reader, encoder, endorser, microfilmer or a pocket module, by way of a document track. Feeding documents from a stack of documents in the above-mentioned manner generally requires advancing the first document in the stack, while inhibiting the remainder of the documents in the stack by a retard mechanism. The next document in the stack follows the trailing edge of the prior document which was just removed from the stack. The retard mechanism of known apparatus uses a roller which operates in a direction opposite to the direction of an associated feed roller. Such a design generally disadvantageously, requires a separate motor for the feed roller and a separate motor for the retard roller. With such feed and retard rollers, it is generally disadvantageously necessary to be very precise in the adjustment of the rollers relative to each other and so, as the rollers begin to wear, additional maintenance or adjustment is also disadvantageously required. Also, the replacement of such feed and retard rollers, when excessively worn, disadvantageously increases the cost of known apparatus and requires that the maintenance be carried out by a service person. Also, the feed and retard rollers often become "glazed" or slippery in use, and consequently lose their effectiveness. The hopper module which contains the stack of documents to be fed generally uses gravity and a spring to feed the documents in the stack to a point where the first document in the stack can be picked from the stack and fed into the document track. One of the problems of known apparatus is that a constant pressure is not readily maintained on the next document to be picked from the stack as the stack decreases in size during feeding of the documents and as the hopper is subsequently replenished with documents. When the pressure is not constant, misfeeds or nonfeeds can result. It is an object of the present invention to provide document feeder apparatus which reduces the likelihood of misfeeds occurring. According to the present invention, there is provided document feeder apparatus comprising a hopper for storing a stack of documents, biasing means for biasing said stack towards a picking station in said hopper, said biasing means being movable to a retracted position to allow for documents to be added to said stack and being releasable from said retracted position so as to move into contact with said stack, and document picker means located at said picking station, characterized by velocity sensing means for sensing the velocity of said biasing means as it moves from said retracted position towards said stack and control means connected to said sensing means for de-energizing said picker means if the velocity of said biasing means exceeds a threshold value. The present invention is advantageous in that it is simple and inexpensive to manufacture, minimizes the amount of adjustment required for the associated parts and provides a variable load applicator on the stack of documents so that there is a relatively constant load at the "picking" mechanism of the apparatus. It is a particular advantage of the invention that once the hopper has been replenished, the pressure of the biasing means exerted on the stack, as it is reintroduced into contact with the stack, does not lead to a misfeed of the documents introduced to the picking station as the biasing means contacts the stack. The invention is described further hereinafter, by way of example only, with reference to the accompanying drawings in which: Fig. 1 is a plan view of apparatus embodying the present invention; Fig. 2 is a schematic diagram showing various friction forces associated with the apparatus of Fig. 1; Fig. 3 is an elevational view, looking from the direction of arrow A of Fig. 1; Fig. 4 is an enlarged plan view of a retard mechanism shown in Fig. 1; Fig. 5 is a side elevational view, taken from the direction of arrow B of Fig. 1; Fig. 6 is an exploded view, in perspective, of a stabilizer member used with the pusher shown in Fig. 1; and Fig. 7 is a schematic diagram of a timing strip used with this invention. Fig. 1 is a plan view of a business machine or terminal 10 in which the apparatus 12 of this invention may be incorporated. The terminal 10 may be an encoder, for example, or other machine mentioned earlier herein. The apparatus 12 includes a hopper module 14, a document track 16, and a control means 18 for controlling the operation of the apparatus 12 in addition to controlling other functions associated with the terminal 10. The function of the apparatus 12 is to pick a first document 20-1 from a stack 20 of documents which are located in the hopper module 14 and to feed the first document 20-1 into the document track 16 which has first and second upstanding side walls 16-1 and 16-2. This process is repeated for the next first document 20-1 in the stack 20 until the entire stack 20 of documents is fed into the document track 16. While the documents in the stack 20 are shown as being of the same size, this is merely a matter of convenience. In reality, a stack of documents can vary in length from about 10.2 cm (4 inches) to about 22.9 cm (9 inches), for example. The top long edge of each document in the stack 20 of documents is shown in Fig. 1. The apparatus 12 also includes feed rollers 22, 24, and 26 which are driven or rotated by an endless belt 28 which is coupled to a drive pulley 30 of a motor 32 which is controlled by the control 18. The feed rollers 22, 24, and 26 have associated pinch rollers 22-1, 24-1, and 26-1 to conventionally move a document, like 20-1, in a downstream direction, which is to the right as viewed in Fig. 1. Additional modules, like an endorsing station or an encoding station (not shown but associated with the terminal 10) may be located downstream of the feed roller 26, for example. The hopper module 14 (Fig. 1) is designed to move a stack 20 of documents along an alignment side 14-1 towards a stop 14-2. A pusher 14-3 resiliently moves the stack 20 of documents towards the stop 14-2. Details of the hopper module 14 will be described hereinafter. The stop 14-2 has an idler roller 32 rotatably mounted thereby, with the idler roller 32 protruding from the stop 14-2 towards the stack 20 of documents to minimize any friction between the stack 20 and the stop 14-2. The idler roller 32 is rotatably mounted on a rod 34 (Fig. 3) which is upstanding from a frame 36 of the terminal 10. The purpose of the apparatus 12 is to pick the documents in the stack 20, one at a time, and feed them at a specific rate, with a gap between successive documents being fed, to the document track 16, which in turn, feeds the documents to a module, like an endorser, for example, which is not shown. The apparatus 12 includes a drive roller 38 (Figs. 1 and 3) and an idler roller 40 which have an endless belt 42 mounted thereon. The drive roller 38 is coupled to the output shaft 44 of a motor 46 to be rotated thereby. The motor 46 is secured to the frame 36, and operates under the control of the control means 18 which includes a controller 18-1. The drive roller 38 and the idler roller 40 have flanges 38-1 and 40-1 which retain the-endless belt on the associated rollers. The idler roller 40 is rotatably supported on a rod 48 which is upstanding from the frame 36. The drive roller 38 and the idler roller 40 are positioned in the frame 36 (Fig. 1) so that the endless belt 42 has a straight or linear portion 42-1 which is parallel to the first document 20-1 to be picked from the stack 20. In the embodiment described, the endless belt 42 is positioned so that the centerline of its width is about 3,3 cm (1,3 inches) above the bottom 16-3 of the document track 16 as measured in a vertical direction, as viewed in Fig. 3. The width of the endless belt 42 is 1.91 cm (3/4 inch) in the embodiment described. Naturally, the specific dimensions and locations of the endless belt 42 can be changed to suit particular applications. The apparatus 12 also includes a retard mechanism 50 shown in Figs. 1 and 4. The retard mechanism 50 functions as a wiper and cooperates with the feed means including the endless belt 42 to permit only one document at a time to be fed from the stack 20 of documents to the document track 16. The retard mechanism 50 includes a support post 52 (Fig. 4) and an arm 54, having one end pivotally mounted on the support post 52, with the remaining or free end having a cylindrical portion 56 which is "C"-shaped in cross section. The retard mechanism 50 also has a retard member 58 which has a first portion 58-1 which engages the stack 20 of documents as shown in Fig. 1, and it also has a second portion 58-2 which is biased towards the linear portion 42-1 of the endless belt 42 by the tension spring 60 shown in Fig. 4. The retard member 58 also has a complementary member 58-3 which extends therefrom to enable the retard member 58 to be mounted on the arm 54 by having the complementary member 58-3 slide into the cylindrical portion 56. The support post 52 and the arm 54 are located below the hopper module 14, and the retard member 58 is positioned in the cylindrical portion 56 so that the second portion 58-2 of the retard member 58 is opposite to and is biased towards the linear portion 42-1 of the endless belt 42. Before discussing the operation of the apparatus 12, it is useful to discuss the friction which exists between certain members of the apparatus 12. In this regard, Fig. 2 shows the various forces working on a document to be fed from the stack 20 of documents and moved to the document track 16. In effect, the documents are separated by differential friction. The second portion 58-2 of the retard member 58 applies a force N (via the spring 60) which is normal or perpendicular to the linear portion 42-1 of the endless belt 42, and the second portion 58-2 also has a coefficient of friction (COF)which is µ₃. The relationship of the COF of each of the members is as follows. The endless belt 42 (Fig. 2) has the highest COF which is equal to µ₁; the second portion 58-2 of the retard member 58 has the next highest COF which is equal to µ₃; and the COF of the documents in the stack 20 of documents is equal to µ₂. Because the endless belt 42 has the highest COF, the force Fadv is the highest, and it is sufficient to drive the document #1 to the right as shown in Fig. 2, while the second portion 58-2 of the retard member 58 provides a force Fretard which is sufficient to stop the second document #2 from being fed to the right. There are inter-document forces Fdoc (shown by arrows 62 and 64). These are some considerations which follow from the various forces due to friction shown in Fig. 2: 1. If the inter-document friction or force Fdoc is too high or the retard friction Fretard is too low, multiple feeding of the documents results; and 2. If the retard friction Fretard is too high or the advance friction Fadv is too low, the documents won't feed. A major part of the design of the apparatus 12 is to ensure that there is no slippage between the endless belt 42 and the document #1 in Fig. 2; this document corresponds to the first document 20-1 in the stack 20 of documents. Relative slip between the document #1 and the endless belt 42 leads to "glazing" of the endless belt 42, and glazing of this belt leads to slippage and a loss of document throughput. Maintaining the required friction of the endless belt 42 is a key to ensuring a successful design. A problem with the documents in the stack 20 of documents is that in addition to coming in a variety of sizes, the documents have varying paper properties. Some of these variations relate to type of paper, thickness, texture, humidity, and surface contaminants, like inks and waxes. Previously, replacement of parts was not necessitated, generally, by wear but by a loss of friction. It is a feature of the present invention that in order to maintain a high friction surface, a controlled amount of wear is desirable in the endless belt 42. Several endless belts, like 42, were tried for the endless belt 42. The material which was found to work the best was a rubber type belt which has some proprietary elements in it. The particular endless belt 42 used is a "Posifeed 3570"™ belt, for example, which is manufactured by and currently available from the Siegling Co. of Charlotte, North Carolina. This particular belt wears out without "glazing." Naturally, other belts possessing these characteristics may be used. Another feature of the apparatus 12 is that when the endless belt 42 wears out, it is easy for an operator to replace the endless belt 42 with a new one. A service call by a maintenance person is not necessary to effect the change or replacement. The retard member 58, in contrast, is made of a material, like urethane, which yields low wear. The cantilever design of the retard member 58 gives some flexibility to the relatively stiff material from which it is made. The flexibility of the second portion 58-2 enables this portion to conform to the linear portion 42-1 of the endless belt 42 without having to maintain tight tolerances between these elements. The arm 54 has a bearing 66 (Fig. 4) in its first end to enable the arm to freely rotate on the support post 52. The spring 60 keeps a sufficient normal force N (Fig. 2) on the endless belt 42. Variations due to wear on the retard member 58 and the endless belt 42 are thereby compensated for by the action of spring 60. The design of the retard mechanism 50 also permits a sufficient "footprint" or area on the rear of the document to perform the restraining function. The retard member 58 can also be replaced, easily, by an operator instead of a service person by simply pulling up on the retard member 58, as viewed in Fig. 4, to remove it, and pushing down on a new one to push it in place. The retard member 58 is also designed to provide a curved "lead-in" from the first portion 58-1 to the second portion 58-2 for leading the documents into the document track 16. The operation of the terminal 10 is as follows. When it is desired to feed a document or documents from the stack 20 of documents, the controller 18-1 (Fig. 1) issues the appropriate signals to the motor 46 to start the picking of the first document 20-1 and to start the drive motor 30 to receive the documents which are fed into the document track 16. The apparatus 12 includes the necessary sensors 68 (shown schematically) which are positioned along the document track 16 to give an indication of the leading and trailing edges of the documents as is conventionally done. A first sensor 68 is located just upstream from the feed roller 22 to monitor the inter-space distance between the trailing edge of one document (the one just picked) and the leading edge of the next successive document. Another sensor 68 is located just downstream from feed roller 26 to monitor the inter-space distance between the documents leaving the apparatus 12, assuming the documents are moving downstream away from the apparatus 12 at a known constant speed. When the motor 46 is stepped or rotated, the first document 20-1 is picked from the stack 20 and moved to the right as viewed in Fig. 1. The retard member 58 then functions to permit only the first document 20-1 to be moved to the document track 16, as previously described. The inter-space distance is achieved by picking the document much more slowly than the speed of the document in the document track 16, thus allowing the trailing edge of the document just picked to move away from the leading edge of the next successive document. When the leading edge of the document just picked is detected at the sensor 68 near the feed roller 26, both motors 46 and 30 are stopped, if necessary, to provide the appropriate inter-space distance between the trailing edge of one document (the one downstream from the apparatus 12) and the next successive document (the one just picked). When the appropriate inter-space distance is reached, both motors 46 and 30 are again energized or stepped to feed the next document. The speed of motor 30 is determined by the required speed of the documents leaving the apparatus 12. It is desirable to pick documents as slowly as possible while still maintaining the required documents per minute feed rate. Accordingly, after each document 20-1 is picked, if the inter-space distance is too-large, the speed of the document picking motor 46 is increased by approximately 1%. If the inter-space distance is too small, the speed of the document picking motor 46 is decreased by approximately 1%. The picking speed is thus varied by the controller 18-1 between the limits of 46% and 60% of the speed of a document moving in the document track 16 and will tend to seek an optimum speed. This process is repeated until all the documents in the stack 20 of documents has been fed. Additional details of the hopper module 14 (Fig. 1) alluded to earlier herein, are shown in Figs. 5 and 6. The pusher 14-3 includes a housing 14-4 having a front planar face or panel 70, a rear panel 72, and side panels 74 and 76 (Fig. 5). The rear panel 72 is shaped to conform to a roller 78 which has a large mass to move the stack 20 of documents towards a picking station which includes the endless belt 42 and the retard mechanism 50 described earlier herein. The roller 78 has a support shaft 80 extending slightly from each side, and the side panels 74 and 76 have mating recesses therein to receive the support shaft 80. The housing 14-4 of the pusher 14-3 is made of plastic, and the side panels 74 and 76 can be pushed apart, slightly, to receive the ends of the shaft 80 to rotatably mount the roller 78 between the side panels 74 and 76. The hopper module 14 also has a left side wall 14-5 (Fig. 1) and a floor 82 with spaced, parallel rails 84 upstanding therefrom to support the stack 20 of documents and to enable the roller 78 to roll thereon with a minimum of friction. The rails 84 are spaced across the entire width of the hopper module 14; however, the pusher 14-3, including the roller 78, extends from the alignment side 14-1 to the idler roller 32, as shown best in Fig. 1. This is the area of the stack 20 of documents which is pushed against the stop 14-2, the idler roller 32, and the linear portion 42-1 of the endless belt 42. In the embodiment described, the roller 78 has a diameter of 4.5 cm (1.75 inches), a length of about 10.2 cm (4 inches), and a weight of about 15 N (3.3 pounds). The angle of the floor 82 of the hopper module 14 relative to a horizontal plane, as viewed in Fig. 5, is about 8 degrees. Under these circumstances the roller 78 exerts a force of about 2 N (0.46 pounds) against the stack 20 of documents. Naturally, for different applications, the parameters of the roller 78 and related elements can be changed. The roller 78 is part of a biasing means which resiliently biases the pusher 14-3 from a loading station, shown approximately in Fig. 5, to a picking station including the linear portion 42-1 of the endless belt 42. The biasing means also includes a tension spring 86 and a coupling means 88 (Fig. 5). The coupling means 88 is used for coupling the housing 14-4 to the floor 82 at a slot 90 (Fig. 1) therein so as to maintain the front panel 70 of the pusher 14-3 parallel to the stop 14-2 and the linear portion 42-1 of the endless belt 42. The coupling means 88 includes a stabilizer member 92, shown best in Figs. 5 and 6. The stabilizer member 92 includes a curved portion 94 and a plate 96 depending therefrom. The plate 96 has a first bearing or idler roller 98 rotatably mounted thereon, and it also has a second idler roller 100 rotatably mounted on an opposite side of the plate 96 as shown best in Fig. 6. The coupling means 88 also includes a plate 102 which has a slot 104 therein to receive the roller 100, with the plate 102 being secured to the underside of the floor 82 of the hopper module 14. The slot 104 is widened in the area 104-1 to enable the roller 100 to be biased towards this area 104-1 by a spring 106 when the pusher 14-3 is pushed slightly to the right of the position shown in Fig. 5 to enable the pusher 14-3 to be detachably held in a retracted loading position. When the pusher 14-3 is in the loading position, a new stack of documents, like 20, may be stacked in the hopper module 14. The spring 106 has one end thereof fitting into a mating recess in the plate 102, and the remaining end thereof is secured to the plate 102 by a screw 108. After a new stack 20 of documents has been loaded into the hopper module 14, the pusher 14-3 is released from the loading position by pushing it slightly to the left with reference to Fig. 5, whereupon the pusher 14-3 moves under the action of gravity and the spring 86 until it comes into contact with the stack 20. The tension spring 86 (Fig. 5) has one end thereof connected to a frame member 110 of the terminal 10 and the remaining end thereof connected to the plate 102 of the stabilizer member 92. The tension spring is designed to be active in helping the roller 78 move the stack 20 of documents towards the stop 14-2 until the pusher 14-3 moves from the position shown in Fig. 5 to a position in which the pusher 14-3 is about 12.7 cm (5 inches) from the stop 14-2 in the embodiment described. This is important in order to have a constant pressure on the first document 20-1 in the stack 20 of documents as the first document contacts the linear portion 42-1 of the endless belt 42 to avoid nonfeeds or misfeeds. The assembly of the pusher 14-3 (Fig. 3) is as follows. After the roller 78 is mounted in the housing 14-4 as previously described and is positioned as shown in Fig. 5, the curved portion 94 of the stabilizer member 92 is passed through the slot 90 (Fig. 1) in the floor 82. Thereafter, the front end of the curved portion 94 fits into an opening 112 in the housing 14-4 and a fastener 114 (Fig. 5) is used to secure the stabilizer member 92 to the housing 14-4. The plate 102 is then secured to the underside of the floor 82. The curved portion 94 of the stabilizer member 92 which fits into the slot 90 (Fig. 1) is used to maintain the front panel 70 of the pusher 14-3 parallel to the linear portion 42-1 of the endless belt 42. When the pusher 14-3 is pushed from the stop 14-2 to the retracted loading position shown approximately in Fig. 5, the roller 98 contacts the underside of the floor 82 and keeps the top of the pusher 14-3 from moving to the right (as viewed in Fig. 5) to prevent binding of the pusher 14-3 relative to the floor 82. A particular feature of the present invention is that a velocity sensing means is employed to detect the velocity of the pusher 14-3 as it moves from the loading position towards the stack 20 of documents. Normally, replenishment of the hopper 14 takes place when the stack 20 of documents has decreased to about the quarter of its original size due to the feeding operation. In order to replenish the hopper (14), the pusher (14-3) is manually retracted to the loading position and, while documents continue to be picked at the picking station (14-2, 42-1), new documents are added to the stack (20). The pusher (14-3) is then manually released from the loading position and moves into contact with the stack (20). The velocity sensing means (116) senses the velocity of the pusher (14-3) during its travel towards the stack (20). If the velocity of the pusher 14-3 exceeds a predetermined level, the pusher 14-3 applies too much pressure to the first document 20-1 as it impacts on the stack 20 of documents, thereby being liable to cause a misfeed or preventing the document from being fed. However, according to the invention, if the predetermined velocity is exceeded, the controller 18-1 interrupts the energization of the motor 46 for a predetermined time until the pressures against the first document 20-1 stabilize to acceptable levels. Thereafter, the motor 46 is energized to resume feeding by the endless belt 42. In the embodiment described, the predetermined velocity is 9,4 cm (3.69 inches) per second, and the predetermined time is 0.26 second. Naturally, different applications might require different velocities and times. To determine the velocity of the pusher 14-3 as it moves towards the stop 14-2, the velocity sensing means includes a light sensor combination, shown schematically as sensor 116, and a timing strip 118 (Fig. 7). The strip 118 has a repeated pattern of a wide bar 120 (4mm), wide space 122 (4 mm), narrow bar 122 (2mm), narrow space 126 (2mm), and wide bar 120, to repeat the pattern, when reading from right to left as viewed in Fig. 7. The controller 18-1 has the necessary software for interpreting the signals from the sensor 116 (Fig. 5). A wide bar 120, followed by a wide space 122 indicates reading in one direction, while a wide space 122 followed by a wide bar 120 indicates reading in the opposite direction. One complete repetition of the pattern of the strip 118 is used to determine the velocity of the pusher 14-3 as it moves towards the stop 14-2. The strip 118 is positioned on the underside of the floor 82 and runs along the length of the plate 102 shown in Fig. 5 to coact with the sensor 116 which is mounted on the stabilizer member 92 to move with the pusher 14-3. The detection of one pattern (two bars and two spaces), starting with any bar or space, is used by the controller 18-1 to calculate the direction and speed of the pusher 14-3. The use of the sensor 116 and strip 118 enables the velocity to be detected substantially along the length of the hopper module 14.

Claims: Document feeder apparatus (10) comprising a hopper (14) for storing a stack of documents (20), biasing means (14-3) for biasing said stack (20) towards a picking station (14-2,42-1) in said hopper (14), said biasing means (14-3) being movable to a retracted position to allow for documents to be added to said stack (20) and being releasable from said retracted position so as to move into contact with said stack, and document picker means (42) located at said picking station (14-2,42-1), characterized by velocity sensing means (116) for sensing the velocity of said biasing means (14-3) as it moves from said retracted position towards said stack (20) and control means (18-1) connected to said sensing means (116) for de-energizing said picker means (42) if the velocity of said biasing means (14-3) exceeds a threshold value. Apparatus according to claim 1, characterized in that said control means (18-1) is arranged to de-energize said picker means (42) for a predetermined time period. Apparatus according to any one of the preceding claims, characterized by resilient means (86) coupled to said biasing means to assist the biasing of said stack of documents (20) towards said picking station (14-2,42-1). Apparatus according to claim 3, characterized in that said resilient means (86) is arranged to assist the biasing of said stack of documents (20) only until said biasing means (14-3) reaches a predetermined distance from said picking station (14-2,42-1). Apparatus according to any one of the preceding claims, characterized in that said hopper (14) has a floor (82) which slopes downwardly towards said picking station (14-2,42-1) and said biasing means (14-3) includes roller means (78) rotatably mounted in a housing (70,72,74) for moving down said slope. Apparatus according to claim 5, characterized in that said biasing means (14-3) includes coupling means (88) for coupling to said floor (82) by way of a slot to maintain a planar face (70) of said biasing means (14-3) parallel to a document abutting surface (14-2,42-1) of said picking station. Apparatus according to claim 5 or 6, characterized in that said floor (82) has rails (84) upstanding therefrom for supporting said stack of documents (20) and upon which said roller means (78) is arranged to roll. Apparatus according to any one of the preceding claims, characterized by resilient means (106) for releasably securing said biasing means (14-3) in said retracted position. Apparatus according to any one of claims 5, 6, 7 or 8, characterized in that said velocity sensing means (116) includes light transceiver means. Apparatus according to claim 9, characterized by pattern means (118) provided on the underside of the floor (82) for receiving light from, and reflecting light to, said transceiver means.

Inventors: GUIDO JOSSEPH, SEYMOUR KENNETH S, SONNENBURG DENNIS T, GUIDO, JOSSEPH, SEYMOUR, KENNETH S., SONNENBURG, DENNIS T.
Applicants: AT & T GLOBAL INF SOLUTION, AT&T GLOBAL INFORMATION SOLUTIONS INTERNATIONAL INC.
Application year: 1993
Main classification: B65H7
IPC codes: B65H3