US 3825251 A
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' non United States Patent [191 Beery et al.
SYSTEM FOR CONTROLLING THE FEED OF DOCUMENTS INTO AND ALONG A DOCUMENT TRANSPORT PATH Inventors: Jack Beery, Farmington; Gerald A. De Carteret, Detroit, both of Mich.
Assignee: Burroughs Corporation, Detroit,
Filed: July 2, 1973 App]. No.: 375,919
References Cited A UNITED STATES PATENTS 3/1962 Solyst 271/57 X 12/1963 Tanguy 271/57 X 11/1966 Jones 271/57 H1972 Beery 271/122 Primary Examiner--Richard A. Schacher Assistant Examiner-Bruce H. Stoner, Jr.
Attorney, Agent, or F irm-Edwin W. Uren; Edward G. Fiorito; Paul W. Fish [5 7 ABSTRACT Disclosed is a control system for document transport mechanism including provisions for controlling the feeding, spacing, and throughput of documents, such as bank checks and the like, into and along a guideway leading from a hopper to discharge equipment which may be a stacker or a series of sorting pockets.
[111 3,825,251 July 23, 1974 The system is capable of operating purely synchronously, purely asynchronously or as a hybrid of the same. If purely synchronous operation is desired, the longest document by its length will determine the constant aiid maximum throughput rate for all other documents. For purely asynchronous operation, each document by its own length determines its own throughput rate. For hybrid operation, a standard document length can be aribtrarily selected whose own throughput rate will be the maximum and also the constant throughput rate for all other relatively sorter documents, and all documents relatively longer than the standard length will determine their own throughput rate by their length which will be less than the standard documents throughput rate.
The system further includes speed retarding means that acts in a digital manner for close control of document speed in the guideway and effects a very efficient separation of overlapping documents clue to the high acceleration-deceleration forces that are quickly built up and, impressed against documents passing through. Additionally, the system includes various rollers disposed serially along the guideway throughput rate.'
57 Claims, 9 Drawing Figures sum 70F 7 3.825.261
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wzsiw P523355? SYSTEM FOR CONTROLLING THE FEED OF DOCUMENTS INTO AND ALONG A DOCUMENT TRANSPORT PATH cRoss REF RENCE TO RELATED PATENTS A patent entitled Document Separator Control System bearing US. Pat. No. 3,635,465 and granted Jan. 18, 1972 to Jack Beery and a patent entitled Controlled Torque Document Feed System bearing US. Pat. No. 3,737,l58 and granted June 5, 1973 to .lack Beery and Donald C. Russell describe and claim document feed, velocity and separator control systems upon which the present invention is an improvement and which are assigned to the same assignee as the present patent application. Also, attention may be called to the patents of Solyst US. Pat. No. 3,027,161 and Zyber US. Pat. No. 3,l59,397 which are assigned to the assignee of the present patent application. I
BACKGROUND OF THE INVENTION 1. Field of-the Invention This invention relates to'the field of sheet item or document feeding and more particularly to control provisions for varying the times of operation of the feed of the documents to the input end of a document transport path, for varying the times of operation and the velocity of the document feed means for impelling the documents into the transport path, and for separating overlapping documents as they are fed into the document transport path.
2. Prior Art I g Previous mechanisms having to do with document feed control at the entrance end of a document transport path did not adequately compensate for queueing documents of unequal lengths thereby leaving the system vulnerable to bunching of documents thereby causing misreading and'missorting of documents and undesired system down time.
With respect to the control of the throughput of the documents, previous workers in this art have suggested the employment of controlled pressures for braking of retarding the documents toassure serial spacing of the documentsalong the transport path. The resultant lag time in feeding back the velocity deviationsof the document'drive member to the velocity control means for the advance of document as well as performing effective separation of overlapping documents.
Another important object of the inventionto employ digital timing logic for controlling document feed on intervals in order to vary the systems throughput rate asynchronously dependent on document length or to keep the throughput rate synchronously constant forcertain desired lengths of documents thereby improving throughput for relatively longer documents while providing a constant maximum throughput for relatively shorter documents.
Another important object of the invention is to provide interdocumental spacing to a degree determined by the speed differentials of document driving members positioned along the transport path in order to define the boundaries of the spacesbetween succeeding documents.
A'further important object of the invention is to em employ high frequency digitized pulsating forces rather than relatively steady forces on a highly accelerating document drive member thereby imposing a series of rapidly applied braking thrusts on the document drive member to reduce it down to a desired average speed for governing the throughput rate.
In carrying out the objects of the invention, a document transport system is provided which is capable of transporting a serial stream of documents of various lengths from a hopper into and along a transport-path at different throughput rates and with various interdocumental spacings and further capable of selfoperably changing to either synchronous or asynchronous operating modes depending on the lengths of the documents. Incorporated in the system is a control circuit which modifies the timing and the operation of the controlling the pressure actuator was due to the analog I nature of the velocity control circuitry.
SUMMARY OF THE INVENTlON I It is an important object of the invention to employ digital timing logic for varying the speed of the document drive elements in order to achieve a desired document throughput rate and interdocumental spacing thereby improving the overall system throughput rate while avoiding problems of document bunching andvide an improved document transport system employing digital rather than analog techniques for controlling document feed or drive meansin relation'to the length of each document and initiates such determination in response to the sensing of the trailing edge of the pre-' ceding document at a point downstream from the feed means. In performing this operation with a mixture of documents of various lengths, the control circuit assigns a particular time frame for each advancing document, with the result that for the synchronous operating mode all documents having a length at or below a prescribed standard the time frames are equal regardless of the length of the documents and for the asynchronous operating mode all documents of a length greater than such standard the time frames will vary depending upon the lengths of the document. Accordingly, the time frames are representative of synchronous periods for relatively short documents and of asynchronous periods for relatively long documents, being directly proportional to their simulated or actual advancement lengths respectively.
The document feed or drive means co-acts with the predetermined time frames representative of the actual or simulated document lengths thereby establishing the throughput rate for each document, using the relationship where the throughput rate is equivalent to the ratio of the document speed to its length. This document feed means, which preferably is a cyclically movable member, and one or more additional downstream higher speed document imparting members, impress a net speed differential upon each document that is high enough so that the previously obtained throughput rate for that document does not vary even though the space between that document and the preceding document is extended to a degree dependent upon the length of the former document.
An important feature of the document transport system is the provision for controlling the speed of the document feed means. Designed to operate in excess of the desired speed for impelling the documents into the transport path, the document driving member is subject to the control of a circuit cooperating with a pressure actuator to retard or brake down the driving member to the desired speed by applying high frequency pressure pulses upon the driving member and any document interposed therebetween. Circuit means continuously determines the velocityv of the document driving member and the extent of any deviation from a predetermined desired velocity and varies the pulsing signals delivered to the pressure actuator in accordance therewith for controlling the impetus with which the driving member impels the documents. The actual velocity and the ideal velocity are continuously compared by digital logic circuitry, and as long as the actual velocity exceeds the desired velocity, a string of rapid pulses for retarding the action of the document driving member will be generated.
Means is provided which will interrupt the string of braking pulses when the string exceeds a prescribed time interval by outputting a blocking pulse to cancel them thereafter so as to compensate for the lag time encountered for the pulsing to take effect due to the multiple mechanism time constants in the system.
An added benefit of the digitizing, pulsing pressure nature of the document velocity control is the high acceleration and deceleration forces built up by the pressure actuator in cooperation with the document driving member on overlapping documents to reduce any incidence of two or more such documents proceeding past the pressure actuator point in the transport path. Those overlapping documents which are statically attracted to one another or are stuck together for some other physical reason are more readily separated from one another when subjected to rapid, digitally applied braking thrust pressures for decelerating the documents while subjecting the foremost document to relatively high accelerating forces imparted by the document drive member.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 3 is a typical multi-stage up-binary counter utilized in the illustrated embodiment of the invention;
FIG. 4 is a timing diagram for the binary counter of FIG. 3 used in the feed control subsystem;
FIG. 5 is a schematic block diagram of the velocity control subsystem together with the mechanism it is operatively coupled to according to the invention;
FIG. 6 is a time chart representing the timing sequences between the document feed and velocity rotors;
FIG. 7 is a timing diagram illustrating the pulsing sequence on a given document and the delayed effect thereon in connection with the circuitry of FIG. 5;
FIG. 8 illustrates the interdocument spacing effect between documents of different lengths in connection with the circuitry of FIG. 5; and
FIG. 9 illustrates the dependencies between the throughput rates and document lengths.
DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION For illustrating a preferred embodiment of the invention, the general assembly of mechanical parts making up the systems disclosed in the referenced US. Pat. No. 3,635,465 and the referenced US. Pat. No. 3,737,158 have been selected for this purpose. Accordingly, the document handling assembly illustrated in FIG. 1 includes: a stack of documents 10 contained within a document storage-hopper 12 adjacent to the input end 14 of a document transport path which is shortly assumed by a pair of parallel side walls forming a guide way 16. The illustrated document handling assembly further includes a document dispensing assembly generally indicated at 18 for dispensing documents out of the hopper and into the input end 14 of the transport path, a document drive unit 20 adjacent to the entrance 14 of the transport path, a pressure actuator unit 22 positioned opposite to the document drive unit and cooperable therewith, a document sensing means 24 further downstream in the guideway 16 which is responsive to the passage of each document, and even further downstream a series of high speed roller pairs 25 for driving the documents along the balance of the transport path.
More specifically, a stack of documents 10 are initially stored, preferably on edge, in the hopper 12 prior to being fed into the entering end 14 of the document transport path. The documents are dispensed from the hopper by the document dispensing unit 18 and thence to the inlet 14 of the document drive unit 20 and pressure applying unit 22. The document drive or feed unit 20 includes a drive member 26 in the form of a roller having its peripheral surface thereof treated or otherwise provided with a layer 28 having a high coefficient of friction. Cooperating with the drive unit, the pressure unit 22 functions both to apply braking pressures on the drive roller 26 to slow it down and to separate overlapping documents one from the other, such as will be performed on the document 30 superimposing upon the leading or foremost document 32 which will be directly engaged by the drive roller 26.
Positioned downstream from the drive roller 26 is the document sensing assembly 24 which in the illustrated system comprises a source of radiant energy or lamp 34 on one side of the guideway and directly opposite on the other side of the guideway a photoelectric cell 36 is positioned to receive the light beam from lamp 34 when this beam is not intercepted by a passing document. Other forms of sensing means may be employed, such as a sonic source on one side of the guideway cooperating with a sonic detector opposite thereto. In whatever form the document sensing provision may take, the detector serves as a transducer to convert the received energy into electrical signals which are utilized by the systems as hereinafter described.
The hopper document dispensing assembly 18 herein comprises a wheel 38, sometimes referred to as a document picker or nudger, which actually may consist of a pair of side by side wheels as described in the aforesaid referenced US. Pat. No. 3,635,465 and which are the hopper is provided with an opening permitting the feed wheel to rise therethrough and into'engagement with the end document in the hopper.
Connected to the opposite end of the lever 42 is a switch mechanism 48 and a constant pressure spring 49. The spring 49 functions to bias the nudger wheel 38 through the opening in the plate 46 of the hopper and against the dispensing end of the stack of the documents 10 in the hopper. The amount of displacement of nudger wheel into the hopper is sensed by the switch mechanism 48 which when actuated electrically causes a motor (not shown) to rotate a lead screw 50 in the hopper and move a backup plate 52 toward the exit end of the hopper to compress the stack of documents 10. As the documents are pressed in this fashion, they will in turn force the nudger wheel 38 andassociated end of the lever away from the hopper, thereby opening the switch 48 and discontinuing compression movement of the backup plate 52.
It should be noted that in the schematic view of FIG. 5 to be described hereinafter, a simplified alternative arrangement is'shown for the feeding of documents from the hopper where a motor 145 has its drive shaft attached directly to the nudger roller 38. I
In addition to the roller 26, the document drive or feed assembly 20 includes, as shown at the bottom of FIGS. 2 and 5, a drive shaft 58 upon which the roller is secured for joint rotation and which in this illustrated embodiment of the invention extends through a high response motor 60, such as a moving coil d.c. printed circuit motor with constant current windings of the type recited in the aforesaid references. Such a motor should quickly accelerate to a speed considerably beyond that needed for driving the documents, but its speed will be held down or snubbed by braking pressures applied by the pressure actuator unit 22 as will be explained in more detail hereinafter. The drive shaft 58 terminates with a tachometer generally shown at 62 in FIG. 5 including a disk 64 which has equally spaced apart radial slits 65 and which is jointly rotatable with the shaft, and further including means for sensing the slots which may be a light source 66 and a solar cell 68 or other detector as mentioned in connection with sensor 24. The alternating light and dark conditions of the solar cell as caused by the passage of the slits thereby will generate electrical signal pulses, the frequency of which will be proportional to the rotational velocity of the shaft 58 and roller 26.
The pressure actuator assembly 22 of the presently illustrated embodiment of the invention, certain mechanical features of which are disclosed in the afore-' said US. Pat. No. 3,365,465, comprises an endless scrubber belt 70 driven by a drive pulley 72 along a closed path defined by a pair of pulley wheels 74 and 76 which are mounted for rotation on the supporting plate 78 for the document handling assembly illustrated in FIG. 1. A linear actuator, which is shownin the form of a solenoid 80, has a sheath protected extension 82 of its armature connected to a pair of triangularly shaped plates 84 (only one of which is shown) carrying rollers 86 and 88 at two comers thereof in the manner shown in FIGS. 1 and 5. The relationship of the coil of the solenoid to its armature is such that upon energization of the coil it will thrust the armature toward the document transport path and by means of the rollers 86 and 88 press the adjacent section of the scrubber belt 70 against the frictional surface of the feed roller 26 with increased pressure and any document interposed therebetween. On the other hand, upon deenergization of the solenoid coil the armature will be retracted by the compression in the belt thereby reducing the pressure exerted by the belt upon the drive wheel 26 and upon a document therebetween. The pair of' pulley wheels 74 and 76 and the pair of rollers 82 and 84 are so mounted as to cause the adjacent section of the scrubber belt to closely hug the periphery of the drive wheel 26. The opposite end of the armature extension 82 projects beyond the solenoid and carries a resilient button 83 which strikes a stop for limiting return travel of the armature.
As described in the aforesaid patent the endless separator belt 70 is preferably a flexible urethane foam belt and has that portion of its extent which is positioned in engaging opposition to the drive wheel 26 moving slowly in the direction counter to the periphery of the wheel. In the illustrated embodiment of the invention herein, the separator belt 70 moves slowly in the same direction as the wheel 26. In either case, one purpose of such movement is to spread the wearof the belt by continuously bringing fresh surfaces of the belt into engagement with the drive roller 26 and the documents fed therebetween. In the normal operation of the document transport system, the drive wheel 26 is operated at a rotational speed of approximately 35 r.p.m. which will apply a peripheral speed to the roller such that the roller speed will have an overall average of approximately 60 inches per second. On the other hand, the drive pulley 72 for the endless scrubber belt 70 will be driven at a rotational speed of l r.p.m. which in turn will move the belt at a surface speed not exceeding a preset value, such as approximately 0.16 inchesper second. Any drive force applied in the belt 70 by the document drive roller 26 to move the belt at a faster rate will be restrained by the drive pulley 72 and its source of motive power. It is evident that the linear speed of the belt 70 is substantially slower than the document drive roller 26 and that regardless of its direction of movement the slow moving belt will retard any overlapping documents not directly engaged by the drive roller. and separate it from the document which is directly engaged by the drive roller and subjected thereby to relatively high speed driving forces.
The foregoing description is primarily intended for the establishment of a suitable mechanical environment for the document feeder control system of the present invention and is approximately the same as that described-and illustrated in the aforementioned US. Pat. No. 3,635,465 and patent application Ser. No. 181,525, now U.S. Pat. No. 3,737,158. The present invention includes further apparatus and electrical circuitry used in conjunction with a suitable environment such as has been described.
Referring to FIGS. 2 to 8 inclusive by the characters of reference, there is illustrated an overall system in accordance with the invention for controlling the movement of documents into and along a guideway leading from a hopper or collection station to a discharge station, overall control over such document movement involving feed control, throughput control and control over the separation of the documents. Included in the control system are subsystems utilizing electrical logic circuits and components for accomplishing the desired ends.
In the schematics of FIGS. 2 and5, all the flip flops shown are J-K type flip flops. The flip flops are negative triggering and where the trigger or T input is used, the flip flop is controlled by a pulse on the trigger line. All of the logic gates are positive AND or OR gates. Thus for an output signal from an AND gate to be true, all of the input signals must be true and likewise, for the output signal from an OR gate to be true, at least one input signal must be true. In the preferred embodiment, the voltage level for a True signal is +v and the voltage level for a false signal is ground. Although AND and OR logic is employed in the illustrated embodiment of the invention it should be understood that NAND and NOR logic is equally applicable especially for use with MOS technology.
A subsystem of this overall control system is the feed control circuit provision shown in FIG. 2, whereby documents 10 are advanced from the hopper or collection station 12 leading to the inlet 14 of a document transport path'and thereafter sequentially along the guideway 16 which may terminate in a stacker or a plurality of sorter pockets (not shown). This feed control subsystem includes the document drive or feed roller 26 receiving documents from the nudger wheel 38 and advance the same into the inlet 14 of the transport path extending between the feed wheel 26 and the adjacent section of the scrubber belt 70 and thence into the entrance of the guideway 16, the sensing means 24 for sensing the passage of a document past a predetermined point downstream in the guideway 16, and an improved feed control circuit embraced within the boundary of long dash lines 100 in FIG. 2 for controlling the document feed roller 26 using signals on line 17 from the document sensing means 24.
In the illustrated embodiment of the invention, the feed control circuit embraced within the dash lines 100 of FIG. 2 is composed of first counting means 102, including a six stage flip-flop first binary counter 104 having one set of timed on" output terminals 106 and a second set of complementary timed off output terminals 106', each set of terminals providing progressively longer on" time periods, as 2.5 ms., 5.0 ms., 20 ms., 40 ms. and 80 ms. duration, going from low to high stages, respectively. The terminal set 106 provides normal signals representing the aforementioned time periods, and the other terminal set 106' provides the complement signals of the first set. This is to say, when a signal appears on a terminal in set 106, the corresponding terminal in the other set 106 does not provide a signal. Although six terminals are shown for each set 106 and 106" of the binary counter, all or any combination of these terminals may be used at any one time with the balance of the circuit. For example, possible combinations are the 5 ms., 10 ms., and ms. terminals or the 10 ms., 20 ms., 40 ms. and 80 ms. terminals, respectively of set 106 are used for the operation of the presently described embodiment of the invention, and two terminals representing the 40/ms. and 80/ms. of set 106 are similarly employed for this purpose, the remaining unused terminals of both sets being reserved for use by other parts of the equipment with which the invention may be associated.
A typical six stage binary up-counter suitable for counter 104 is illustrated in FIG. 3. The chain of the six flip-flops Al to A6 and their respective input and out interconnections are shown in this Figure together with the normal and complementary terminals 106 and 106,'respec'tively, which are identified in FIG. 2 by their respective time periods in milliseconds. The binary counter 104 receives clock pulses from a clock pulse generator herein shown in the form of 2.50 ms. crystal controlled square wave oscillator 108 which serves to clock the binary counter. In the operation of the binary counter 104 in the illustrated embodiment of the invention, the counter is conditionally cut off at the selected synchronous time period which in this example is the combination of the second, third and sixth stages of the counting shift register 104 as represented by the normal outputs 5 ms., 10 ms., and 80 ms. equaling ms., at which time the counter will hold until a signal originated by the document .sensing means 24 is received for recycling the counter. The cut off of the counting of the binary counter 104 may be accomplished by tapping the 5 ms., 10 ms. and 80 ms. outputs and AND gating them by gate 110 in the manner shown in FIG. 3 and employing the resultant signal on line 112 to reverse bias the first stage of the binary counter which will stop the counting of the counter. This condition will remain until a document trailing edge signal is sensed so as to reset the binary counter for a new counting cycle.
Referring to FIG. 4, the three normal outputs 5 ms., 10 ms., and 80 ms. of the binary counter 104 limit the counting to 95 ms. as previously mentioned, which cutoff point in the counting cycle is indicated by vertical line 114. The concurrent receipt of the two complementary outputs 40/ms and 80/ms. of the binary counter provide a time period during which the binary counter cannot be reset as will be later described herein, the limit of the period being indicated by vertical line 116 in FIG. 4.
The binary counter 104, upon counting up to a predetemiined point consisting of the three separate time on periods of 80 ms., 10 ms. and 5 ms. or on" signals of subset 106, which collectively represent a duration of 95 ms., will generate a standard or synchronous period of time represented by an output signal signifying the 95 ms. duration at their respective output terminals. This output signal will be conveyed by leads within a conduit or cable to other components of the circuit as described hereinafter. Such a time period signal represents in the illustrated embodiment of the invention the transit time for the trailing edge of an avproportional to the documents actual length.
When the binary counter 104 outputs the complements of the 40 ms. and 80 ms. signals at any given point in time, a non-occurrence of a standard time period will be indicated thereby. The binary counter 104 will then output on complementary terminals 40/ms. and 80/ms. a non-standard time period signal representative of the duration of 37. ms. for indicating the unconditional feed on interval for the document feed member 26. Leads connected to the two complementary terminals are enclosed within a conduit or cable 132 for conduction to other components of the control circuitas later described herein. A signal representativeof the fifth state on. signal is outputted on the 40 terminal on line 133 for conduction to other components of the control circuit as later described herein. A second signal representative of the sixth stage on" signal is outputted on the 80 terminal on line 135 for conduction to other components also of the control circuit as later described herein.
It will be noted that the 95 ms. time period configuration just described is for the 600 dpm mode. If 400 dpm mode is desircd, all that is necessary is to switch the jack from the 5 ms. terminal to the ms. terminal and connect a fourth jack to the 40 ms. terminal as represented by dotted lines 131 in order to obtain a longer time period of 150 ms. which provides a totally synchronous operation as will be explained later herein. By the above accommodation, synchronous operation may be had at almost'any point between 37.5 ms. and 150 Enclosed within the dotted outline 134 (FIG. 2) is a bistable device in theform of a control flip-flop 136 used for driving the document feeding means or roller 26. By line 137 flip-flop 136 is clocked by a high frequency clock pulse generator in the form of a 5 us. (mito the document feed motor 60 to bring the motor to a fast stop for a short time interval, such as 5 ms. After the 5 ms. unconditional stop interval, the DMV 67 is in a conditional stop mode so that upon receipt of a new driving signal on line 147, it will output normal polarity power current on lines 69 to drive motor 60. The unconditional minimum 5 ms. motor stopping interval for motor 60 will allow-the preceding document to spaceout to at least a controllable minimum distance from the subsequent document which is held up by the stoppage of the motor. The motor stoppages provide an average speed for the document feed roller which is substantially lower than that of the high speed downstream rollers 25. As will be more fully explained hereinafter, this speed differential provides the basis for the relative interdocumental spacing.
As will be more fully explained hereinafter in connection with the operation of the system as a'whole, the elapsed or transit time for relatively long documents will exceed the standard time period of 95 ms. using the 600 dpm mode. The net result in such a case is that the flip-flop 136 will remain on after the binary counter has reached 95 ms. and continue to be on until the sensor 24 has sensed the trailing edge'of the document which will then cause the operation of the binary counter to recycle.
Enclosed within the dotted outline 148 is a bistable device in the form of a first reset flip-flop 150 used cooperatively with a second reset flip-flop to be described hereinafter for resetting the binary counter 104. The flip-flop 150 is pulsed by the high frequency clock pulse generator 138 previously described. Gating 7 means in the form of a gate 152 will output a biasing crosecond) crystal controlled square wave oscillator 138. A circuit logic component in the form of an AND gate 140 will produce a biasing output signal on line 142 to the J input of flip-flop 136 when the binary counter complementary terminals 40 ms. and 80v ms.
signify a non-standard time period of 37.5 ms. or less and will convey such time period signals by conduit 132 concurrently to the two inputs of gate 140. The resulting enabling pulse on line 142 will trigger the flip-flop 136 to its on" state causing it to output an actuating signal on line 144 to the drive amplifier 143 which in turn delivers a driving signal on line 147 to the delayed monostable multivibrator (DMV) 67 which in turn designal on line 154 directly to the input of the flip-flop 150 and indirectly through an inverter 156 which will reverse bias the K input of flip-flop 150 when the output time signals comprising ms., 10 ms. and 5 ms. from the binary counter 104, and collectively representing the standard time period signal'of ms., are concurrently received by the three-inputs of AND gate 152 thus enabling the first reset flip-flop to be triggered to its on state for producing a conditional resetting signal on its output line 158. When no signal is received by gate 152, the flip-flop 150 will be triggered to its off state thus terminating the outputtingof the conditional reset signal on line 158.
Enclosed within the dotted outline 160 is a second bistable device in the form of flip-flop 162' which cooperates with the first reset flip-flop 150 for resetting the binary counter 104. The flip-flop 162 is clocked by the previously described time generator 138. Whenever gating means in the form of AND" gate 165 receives signals on lines 135 and 146 simultaneously, it will output a signal on line 166 to the OR gate 167, similarly, whenever gating means as AND gate 163 receives signals/on lines 133 and 146 simultaneously, it will output a signal on line 161 to the OR gate 167. When the OR gate has been put in a true state by inputting signals 161 or 166, it will output a signal on line 169 to bias the J input of flip-flop 162 thereby enabling it to be triggered to its 1 state thus producing a second conditional resetting signal for cooperative resetting on line 168. Gating means in the form of AND gate 174 is connected to the flip-flop outputs 158 and 168 and upon the concurrent receipt of the two conditional reset signals it will produce an unconditional reset signal which will be reverse biased by inverter 171 to-output on line 176 to the plurality of reset inputs of binary counter 104 as shown in FIG. 3 thus resetting the binary counter to zero. Gating means in the form of AND gate 170 will output a biasing signal on line 172 to the K input of flip-flop 162 when the complementary output terminals 40 ms. and 80 ms. of subset 106' of binary counter 104, representing the non-standard time period signal, are received simultaneously by gate 170, thereby enabling the flip-flop 162 to be triggered to its of state thus terminating the outputting of the second conditional reset signal on line 168. The net result of the interaction between the first and second counterv reset devices 148 and 160 is to control the resetting of the binary counter 104 such that only after the counter has reached its standard time period of 95 ms. and also a trailing edge of a document has been sensed will the counter be reset to zero to thus reinitiate the feeding sequence.
A second subsystem of the overall control system is the document throughput control provision shown in FIG. 5 for controlling the introduction of documents into and along the transport path 16. This provision includes the cyclically movable member or drive wheel 26 for moving documents along the transport path, the velocity-sensing means 62 for providing a continuous determination of the speed of the drive wheel 26, the circuit means illustrated in FIG. 5 for producing a pulsating signal in response to signals from the velocitydetermining means 62, and the pressure actuator assembly 22 which utilizes the pulsating signals to apply pulsating forces upon the highly accelerating drive wheel 26 and any document interposed therebetween to brake the drive wheel down to the desired speed. Such pulsatingforces will not only limit the'rotating speed of the drive wheel 26, but also as a result of the pulsating force of the pressure actuator it will limit or hold down the velocity of the documents in the transport path passing between the scrubber belt 70 of the pressure actuator and the document drive roller 26. By controlling the velocity of the drive wheel 26 in this manner, the throughput rate will be proportionately controlled also where such througput rate is a function puts. Accordingly, starting with the lowest counting stage, the first on and off" outputs are designated Z1 and Z1/ respectively where Z1 will indicate the permissible time when the drive flip-flop 212 must be switched of second stage on and off outputs are designated Z2 and Z2/ outputs respectively where Z2 will indicate the permissible time when the drive flip-flop 212 may be switched on; and the third stage on and of outputs are designated as Z3 and Z3/ outputs respectively where Z3 will indicate the permissible time when the ideal time counting means 194 may be reset. The binary counter 190 is clocked by signals on line 191 from a relatively high frequency clock pulse time generator 192 (as compared to time generator 196) having a period of 5 us. (microseconds) which may be a crystal controlled square wave oscillator. The binary counter 190 will not count beyond Z2 plus 23 but rather will stay at Z2 plus Z3 until reset because of a self-biasing feedback arrangement similar to binary counter 104. The actual completion of a predetermined movement by the driving roller 26, such as the distance separating adjacent slits 65, is sensed by the velocity-determining assembly 62 which will send a signal on line 228 as each slit 65 is sensed to the binary counter 190 resetting it to zero. The binary counter 190, in effect, will establish a status time frame within which a comparison can be made for indicating when the drive flip-flop may be switched on" or off and additionally by its reset points, give indication of the actual velocity of the document drive roller 26, the purpose of which will be explained more fully hereinafter.
A second timing means or counting provision is included in the circuit of FIG. 5 taking the form of binary counter 194 having six flip-flop stages each having on and complementing off outputs. The sixth or final stage on output of the counter 194 produced on line 195, hereinafter referred to as Y6 output, represents in the illustrated embodiment of the invention a predetermined standard time of 2.176 ms. for a predetermined movement of the document drive member 26. As mentioned earlier, this predetermined movement of of the velocity of the drive wheel and the length of the documents engaged thereby and introduced into the guideway 16. An additional advantage is the assistance gained in separating any overlapping documents from the foremost document directly engaged by the drive wheel 26.
A preferred embodiment of the document throughput control subsystem includes separate means which are provided for establishing the real and the ideal velocities of the drive wheel together with additional means for comparing the respective two velocities. Only when the real velocity is greater than the ideal velocity will action be taken to limit the drive wheel velocity down to the ideal velocity. Specifically, when the document drive roller 26 has moved a predetermined distance, a brief finite time will be provided in which the actual or real time as measured will be compared to a standard or ideal time to move the predetermined distance. When the actual time is less than the standard time, as sampled within the time frame, then the roller 26 must have its speed retarded. To this end there is provided a timing means or counting provision in the form of a binary counter 190 similar to the previously described binary counter 104 but having three flip-flop stages each having on and complementing off outthe drive member 26 is the distance separating any adjacent pair of the radial slits on the disk 64. The binary counter 194 is clocked by signals on line 199 from a relatively low frequency clock pulse time generator (as compared to time generator 192) such as a crystal controlled square wave oscillator 196, having a period of 64 us. (microseconds). The binary counter 194 will not count beyond the Y6 stage output but will stay at stage Y6 until time of reset, by virtue of a self-biasing arrangement similar to binary counter 104. Depending on the desired throughput rate, other combinations of stages for the binary counter 194 could have been used. Gating means in the form of AND gate 198 is connected to the complementing Z1/ and Z2/ outputs and the Z3 output of the binary counter and will output a signal on line 200 when all of these three output signals are concurrently received by the AND gate for resetting the binary counter 194 to zero. The binary counter 194, in effect, represents the desired standard velocity for achieving the selected document throughput rate.
A bistable device in the form of flip-flop 202 for sampling for a Y6 output on line 195 has a sampling output state and a non-sampling output state designed hereinafter as S and 8/ respectively. The flip-flop 202 is ".13 clocked by signals on line 191 from the clock pulse time generator 192. The flip-flop 202 can be triggered to its S output state by a Y6 signal on line 195 to the J input thereof. The flip-flop 202 can be triggered to its S/ outputstate by the absence of a Y6 signal because the K input thereof is always grounded.
Gating means in the form of AND gate 204 will output a signal on line 206 when Z3/, Z2 and S/ signals are received concurrently thereby. Another gating means in the form of AND gate 208 will output a signal on line 210 when Z1, Z2/ and Z3/ signals are received concurrently thereby.
A bistable device characterized by flip-flop 212 is associated with the'solenoid 80 of the document separator and pressure actuator assembly '22 through a driving amplifier 211 so as to cause the pressure actuator to limit the velocity of the document driving member 26. Flip-flop 212 has a driving output state and a nondriving output state designed as D and D/ respectively. The flip-flop 212 is clocked by pulse signals on line 191 from the clock pulse time generator 192 and can be triggered to its D outputstate by a signal on line'206 pulses is as follows: Using the given 5p.s. clock l92,'the
from AND gate 204 to the J input thereof. Flip-flop 212 can be triggered to its D/ output state by a signal received by the K input online 230 which is outputted on line 210 from AND gate 208 and is ORed through OR gate 231 as later described herein. Referring to FIG. 7 and FIG. 5, it can be seen that the logic pulsing as represented at 238 of drive flip-flop 212 is delayed by five microseconds from reacting to the slip sensing shown in 235 due to the need for the logic circuit to determine whether or not speed correction is needed according to the status at that time of binary counter 190.
A block pulse clock generator 214, which may take the form of a delay monostable multivibrator (DMV) or a crystal controlled elapsed time counter, is triggered .by a D signal on line 216 and will count for 10 ms. then output a signal on line 218 for a 10 ms. interval. The output signal on line 218 from the delay monostable multivibrator 214 branches to provide a first signal on line 220 and a second signal on line 222. An inverter gate 224 inverts the second signal so that it becomesan inverted output on line 226. Output signals on lines 206 and 220 have a common terminal so as to produce a signal on line 218 entering the J input of flipflop 212, thereby switching or triggering the flip-flop 212 on the next clock pulse received by it. Output lines 210 and 226 both input into the OR gate 231 so as to produce a signal on line 230 entering the K input of flip-flop 212 when either 210 or 226 signals are present.
Making reference to FIG. 7 as well as FIG. 5, when the DMV 214 is activated by a D signal on line 216 indicating that the actual or real speed of the feed wheel 26 is greater than the desired standard speed, it will delay any action for a first 10 ms. time interval thereby allowing flip-flop 212 to power pulse the associated solenoid 80 with an overall pulse up to 10 ms. as shown by the pulsing interval 232 in FIG. 7, for the purpose 7 of correcting the speed of the document feed wheel 26 and thereby the throughput of the document being acted upon. Next, duringa second 10 ms. time interval 234 (FIG. 7), the .DMV 214 will output a signal to cancel any bias applied to the J input and concurrently normally-bias the K input of flip-flop 212 to thus turn off flip-flop 212 thereby disallowing any power pulsing to the associated solenoid 80 during this second interval. These first and second time periods of conditional pulsing for speed correction and unconditional nonpulsing for non-speed correction respectively provide document velocity correction to the degree needed, but do not allow over-correction of velocity to take place which would otherwise be the result if time lags introduced by mechanism time constants of the system were not compensated for.
It is an additional feature of each power pulse interval, that the logic pulsing occurring within this interval will be sharply delineated as between individual pulses so that when flip-flop 212 (FIG. 5) is clocked or triggered on for an effective interval, the logic pulsing sent to the associated solenoid 80 will reflect a relatively steep falling off and steep return of the power signal between each effective logic pulse. The manner in which the flip-flop 212 outputs these effective logic drive flip-flop 2l2 could be alternately switched on and of ata 51.4.5. rate if the velocity sensing means 66-68 should be designed to detect the slits 65 on the photo disk 64 also at this rate..ln the herein presented mode of operation, this will not happen due to the rela tively low speed of the motor 60. Actual on off switching rates of the pressureactuator 22 effective for separating overlapping documents will usually occur in the low millisecond time period range even though ineffective switching rates may be realized for periods of shorter duration. The actual switching rate at any given time is dependent on the document friction surfaces in contact with the drive wheel 20 and the separator member 70 which will determine how effective the pressure actuator 22 will be in retarding drive wheel 26 speed and thus what the switching rate of pressure actuator 22 must be. The afore-mentioned advantages of having nearly vertical slopes defining the drive pulses thus enabling them to be effective, for purposes of separating overlapping documents, can only be realized when the pulse duration against the given document surface is or appears to be 2.176 ms. or longer. A series of closely spaced logic pulses can give the net impression of one effective pressure actuator pulse even though individually none of them would so qualify due to the insufficient pulse of time 236 between pulses. Thus, in an overspeed condition, any given one logic pulse will notbe any longer in duration than 2.176 ms. 237 as this represents a drive wheel speed just under the ideal drive wheel speed of ips whereby the ideal drive wheel speed does not require any braking thrusts by the pressure actuator 22. Under actual conditions as shown in FIG. 7 a series of non-effective logic pulses of varying durations may precede one effective logic pulse which when considered together will effectively pulse 238 the pressure actuator 22 to retard the drive wheel s velocity and the throughput rate of documents passing therebetweendown to a desired level. As earlier mentioned briefly herein, it will be noted that within the period of the effective pulse as indicated by the bracket 238 in FIG. 7, the duration of the individual pulses vary down from 2.15 ms. to 2.10 ms. then vary up from 2.10 ms. to 2.176 ms. The reason being that there is some lag in reaction time to the logic pulsing in regards to the correction of speed. The non-pulsing interval indicated by the bracket 233 is of sufficient duration (2.170 ms.) so that pulses 238 and 239 will each appear to be effective in their own rightEffective pulse 239, because of the later occurrence of the unconditional 10 ms. nonpulsing interval 234 is allowed to pulse only 1.389 ms. of the 2.176 ms. that it would have pulsed otherwise. The example shown in FIG. 7 represents a pulsing sequence that may typically happen-in the operation of the equipment disclosed depending on the friction coefficient of documents passing through and other environmental dependencies. The positive advantages of these relatively quick downswings and upswings of the output signal 232 from flip-flop 212 will be brought out in more detail in the description of the operation of the system.
It should be appreciated that every document introduced into the transport path is never out of operative engagement with the feed wheel 26 or one or more of the faster rollers 25 downstream in the guideway 16. Furthermore, every document will be momentarily in contact with both the feed wheel 26 and the initial set of faster rollers 25 as it moves from one to the other along the transport path. When such occurs, the feed wheel 26, by virtue of its higher effective friction coefficient and the associated gripping pressures that are rate of 600 dpm for this mode because all documents 6 inches will be given a simulated period that is 95 ms. When the binary counter 104 has been reset to zero, it will begin to count until it reaches 95 ms. Concurrently at the time of reset of the binary counter, the feed motor 60 will be turned off unconditionally for 5 ms. by virture of the binary counter having been reset,
' thereafter the feed motor will turn on and stay on for applied thereto, will dominate or override the faster rollers and will hold the document down to the peripheral speed of the feed wheel. Once free of the feed wheel 26, each document will then be under exclusive control of the faster rollers 25 in the guideway and will be moved at a substantially higher speed than when under the control of the feed wheel. Until the trailing edge of the document passes by the sensor 24, the feed wheel 26 will continue to rotate and in so doing will advance the next successive document part way through the throat passage with the result that the leading portion thereof will project slightly beyond the feed wheel. Once the trailing edge of the leading document is detected by the sensor 24, the feed wheel is quickly stopped for a time interval that will vary dependent upon the length of the document with which is is now in operative engagement.
OPERATION Summarizing the operational modes of the system: A meritorious feature of the system is its capability of being operated at different throughput rates. In the illustrated embodiment of the invention this is demonstrated by two throughput speed modes, as shown in FIG. 9, a relatively fast 600 dpm hybrid asynchronoussynchronous mode 242 or a relatively slow 400 dpm synchronous mode 244.
The faster 600 dpm is a hybrid mode, the reason being that for document lengths equal to or less than 6 inches, 258, the system illustrated herein operates synchronously, while for document lengths of greater than 6 inches and up to the maximum length of 8% inches, 260, the system operates asynchronously. It should be understood that the selected length of 6 inches which determines the maximum throughput is somewhat arbitrary and may be considered as representing those document lengths that statistically occur the oftenest, where it is assumed that a mixture of relatively long and short documents will be sent through the system.
Referring to FIGS. 4, 6 and 9, synchronous operation 246 for the 600 dpm mode functions only when the document length is s 6 inches. The synchronous time period of 95 ms. is the average time to process 6 inch documents. The 95 ms. time interval being the synchronous period, it also defines the constant throughput 32.5 ms. unconditionally. It should be noted that the feed wheel flip-flop 136 will produce a drive signal unconditionally for the first 37.5 ms. but that for the first 5 ms. of that interval the drive signal will be suppressed by blocking action of the DMV unit 67. The sensing of the trailing edge of the preceding document by the sensor 24 will turn off the feed motor 60 any time after the mark 116 represented in the time scale of FIG. 4 and up to the ms. markll4 of this scale. If the trailing edge signal was sensed before 37.5 ms. (mark 116) had elapsed, then the feed motor will turn off right at mark 116. In the 600 dpm synchronous mode, when the binary counter attains 95 ms., (mark 114) the whole system recycles again.
For a asynchronous operation 248 the 600 dpm mode operates only when the document length is greater than 6 inches, the asynchronous period being variable and dependent on each document length. Once the binary counter 104 has been reset to zero, it will begin to count and by definition will continue until 95 ms. is reached. At the 95 ms. level, the binary counter will hold and will continue to hold until a document trailing edge is sensed which will reset and thereby start the recycling of the binary counter. For documents within the range of greater than 6 inches and up to 8% inches the document trailing edge may be sensed anywhere from 95 ms. to 138 ms. elapsed time respectively depending on the length of the document, thus the throughput rate will also vary from 600 dpm to 400 dpm respectively. Reference may be made to FIG. 9 where this asynchronous operation is denoted by slope 240. Concurrently with the resetting of the binary counter, the feed motor will turn off, then immediately turn on after the 5 ms. stopping interval, thus the entire sequence of events is reinitiated.
The 400 dpmmode 250 operates synchronously only, regardless of the document length. The synchronous period of ms. is longer than the single period of any one document in the range of document under consideration. Because of the longer period (150 ms. v 95 ms.) all documents up to the maximum length of 8% inches must be each processed in this period, but because only one document can be processed per time frame or 150 ms. period, this operates to slow the throughput rate for this mode down from the previously described maximum of 600 dpm to a constant 400 dpm for this mode. Because the 400 dpm mode always operates synchronously, the explanation given for synchronous operation of the 600 dpm mode is equally applicable here. The only difference is the different time periods (150 ms. v 95 ms.) and the document lengths range (4% inches to 8% inches v 4% inches to 6 inches) respectively allowable for the 400 dpm mode versus the synchronous operation of the 600 dpm mode respectively.
Referring to FIG. 8, once the document period is as-v certained, the documents length whether actual or simulated, will also be defined, which when combined with the peripheral speed of the document feed member 26 will determine the throughput rate according to the following formula:
An example of this is in the '600 dpm mode which would be as follows: In the synchronous mode for any document equal to or less than 6 inches (cut-off length), the simulated document length will be 6 inches. The average speed of document driving member 26 will be 60 ips (inches per second) as will be discussed in the subsequent paragraph, thus throughput rate is equal to 600 dpm (documents per minute).
Viewed in another way, the drive wheel 26, by imparting a desired peripheral velocity to documents passing thereby, may be regarded as a means of establishing an allowable throughput rate range within which the exact throughput rate for any given document will be a function of its own length.
Referring to FIG. 8, in all modes there is a need for interdocumental spacing. This is accomplished by turning off the high accelerating drive motor 60 for an unconditional ms. interval depending on the documents length every time the trailing edge of the preceding document is sensed. The turning off and on of the motor 60 for this purpose has the net effect of lowering the average peripheral speed of the document feed means or wheel 26 down to 60 inches per second, and also of momentarily holding back the document 252 immediately subsequent to the document 254 whose trailing edge is sensed. An additional advantage gained from quickly turning off and on the motor 60 is the digitizing effect realized, thus separating overlapping documents in a manner similar to that done by the pressure actuator as will be explained in detail further on in this description. Further downstream from the document trailing edge detector 24 in the guideway are the document drive rollers 25 also operating on passing documents where the peripheral speed of such rollers is 150' inches per second. This relatively constant speed differential between the document feed wheel 26 and the rollers 25 has the net effect of spacingthe documents. Given these speeds, the spacing between documents will be approximately 1 times the length of the subsequent document according to the following formula: SDL subsequent document length DR speed of drive rollers (25) FR speed of feed rollers (26) Interdocumental spacing (IDS) SDL (DR/FR 1) i As an example of this, referring to FIG. 8, if DR 25 is Referring to FIG. 7, it is desirable to keep the document driving member 26 rotating at a desired peripheral speed when its motor is turned on thereby in turn giving documents passing by the desired throughput rate. To accomplish this, a highly accelerating motor has, been chosen to drive the document feed member 26 which has maximum peripheral speed substantially in excess of the desired peripheral speed. The pressure actuator 22 will impose high frequency braking'thrusts against the document driving member 26 retarding its peripheral velocity. and the throughput rate of documents passing therebetween down to a desired level. In the illustrated embodiment of the invention,
18 only amaximum of approximately four of these effective logic pulses will occur in any given sequence, that is to say, in a total pulsing'time frame of 10 ms., after which the circuit logic is inhibited from energizing the pressure actuator for 10 ms. so as to compensate for mechanism time constants of the system.
Referring to FIG. 5 and FIG. 7, the exact interactions between the mechanism and the circuitry in regards to velocity control are as follows: After being reset by the detection of a slit 65 by the movement-determining means 66-68, the status counting means 190 will commence counting. When the status counting means reaches its third counting stage or Z3," the ideal or standard time counting means 194 will be reset and commence counting. If the next slit 65 is detected by said movement-determining means 66-68 in less than 2.176 ms. from the'time that the last one was detected, then the cyclically movable member 26 is moving too fast. In such a case, the Z1 stage will switch the flipflop 212 off and 5 ms. later the Z2 stage will switch the flip-flop 212 back on for logic pulsing to energize the pressure actuator 22 and thereby brake the cyclically movable member 26 at least until the next subsequent slit 65 is detected. Alternatively, if the next slit is not detected until after 2.176 ms. from the time that the last one was detected, then the cyclically movable member 26 is moving slower than the desired ideal speed. In such a case, the Z1 stage will switch the flip-flop 212 of and the Z2 stage will be inhibited from turning on the flip-flop 212 thereby leaving flip-flop 212 in an off" state with the result that the pressure actuator 22 will not be energized and thus no braking of the cyclically movable member 26 will be had until at least the time the next subsequent slip is detected.
Referring to FIG. 5, another important aspect of the feed control subsystem is the indirect but substantial effect ithas on separating a plurality of overlapping items or documents 10 passing between the cyclically movable driving member 26 and the pressure applying belt member 70 into a serial stream for efficient handling downstream in the guideway 16. The document feed member 26 moves in a first or forward direction at'what approaches a normal or ideal speed. Thebelt member moves at a second speed much slower than the normal speed of the drive member26. As previously considered herein, the pressure actuator will apply effective pulsating forces to the scrubber member 70 which will in turn apply the effective pulsating forces to the drive member 26 and any documents interposed therebetween in order to slow it down to ap proximately the normal or ideal speed.
When a single item or document 32 enters the area between the document drive member 26 and the belt member 70, the feed member 26 will be in operative contact with a first broadside surface of the document to move it in the first direction and at the peripheral speed of the feed member 26 due to its relatively high friction coefficient. The document 32 will be also exposed on its reverse or second broadside surface to the belt member 70, but will not be significantly affected by it due to the relatively lower friction coefficient between the foremost documents second broadside surface and the belt member 70, as compared to documents first broadside surface and the friction coefficient of the feed member, and likewise the second speed of the belt member 70 being so much slower than the drive members speed, it will not significantly affect the document.
When a plurality of documents are presented to the input end 14 of the transport path, the relatively low friction coefficient of the belt member 70 should be higher than the interdocument friction coefficient of any overlying documents 30 under ideal conditions and thus under ideal conditions the belt member 70 should be able to hold back and separate any overlying documents 30 thereby allowing only the foremost document 32 to pass through in the first or drive direction due to its higher frictional contact with the drive member 26. The above operation will operate under even less than ideal conditions which may occur when the moisture content of the documents is relatively high tending to make them stick or when static electricity attracts the documents to one another contributing to a relatively high interdocumental friction coefficient.
The present invention provides a solution for problems such as those encountered above. The document feed member 26 applies an initial high acceleration force in the first direction to the first broadside surface of the foremost document 32 and thereby also to the overlapping documents 30. The pressure actuator 80 applies sharp effective pulsating forces through the belt member 70 to one or more overlapping documents 30 and the foremost document 32 resulting in relatively high acceleration/deceleration forces being applied to those documents (See FIG. 7). The resultant braking impulses will overcomethe inertia of the overlapping documents 30 due to their low interdocumental friction coefiicient and thereby cause all of them to lose adhesion and separate from each other and the foremost document. Thus, in that instant when the documents movably slip with respect to'one another, their interdocumental friction coefficient approaches zero thereby making them extremely susceptible to the now relatively much higher friction coefficients of the feed wheel 26 and the belt member 70 resulting in the advancement of the foremost document 32 and the holding back of the one or more overlapping documents 30. The only document that will pass through at any given time thenwill be the front document 32 whose velocity will be that of the peripheral surface of the drive member 26 because the first broadside surface of the document is in direct contact with the drive member 26 whose relatively high friction coefficient disallows any separation between the front document and the drive member. The advantages of such instantaneously high acceleration/deceleration braking forces would not be realizable with inexact and slower reacting analog systems but rather only with an effective digitizing pulsing system as has been described herein.
It is apparent from the foregoing description that the invention has the ability of taking successive documents from a hopper and feeding them serially into a transport path at a throughput rate that is constant for document lengths less than a given length and lengthdependent if above the given length. A distinctive feature lies in coacting a document driving member that is accelerative in its effect with a speed retarding member that outputs, at a variable frequency, a stream of digitized pressure braking pulses of equal magnitude to slow the driving member and documents flowing therebetween down to a desired throughput rate. The resultant effect is' to give very close control of the throughput rate by changing the frequency rate of the digitized power pulses and additionally any overlapping documents will be subjected to the shock effect of such digitized pulses to assist in their separation. After each document has cleared a predetermined downstream point, the document driving member will be abruptly powered down, and the shock of this interruption will be felt by the succeeding document and any other overlapping therewith and thereby lossening any statically or otherwise attracted overlapping documents to assure their separation. Downstream from the first document drive member is a second speed imparting member whose relatively higher speed creates a speed differential which, together with the throughput rate of the next subsequent document, will be effective to give an adequate spacing between documents in the transport path.
From the foregoing description of a specific apparatus illustrating the fundamental features of the invention, it will now be apparent to those skilled in the art that the invention may be constructed in a variety of forms without departing from the true spirit and scope thereof. Accordingly, it is to be understood that the illustrated apparatus disclosed herein is a preferred embodiment of the invention and that the invention is not to be limited thereby but only by the appended claims.
What is claimed is:
1. A mechanism for feeding and separating documents in singular order from a stack thereof, comprising:
means for initiating the flow of individual documents from the stack; feed means including a cyclically movable document drive member and carrying a frictional document engaging surface positioned adjacent to the initiating means to receive and to move each document along a feed path; retard means for slowing the movement of each document along the path, said feed and retard means cooperating to form a throat passage therebetween through which the documents are singularly fed;
means for applying driving forces to said cyclically movable member tending to move the same and a document engaged thereby at a speed substantially in excess of a desired linear speed; pulsing means for applying pulsating braking forces on said retard means to cause the same to transmit such pulses to said document drive member to slow its cyclical movement and a document engaged thereby down to said desired linear speed; and
means for varying the number of pulsating forces applied by said pulsing means to said drive member directly in proportion to the difference between said desired and excess speeds. 2. In a mechanism for feeding and separating documents, as defined in claim 1 wherein said means for applying driving forces further includes control means including:
means for sensing-the trailing edge of a document at a point downstream from said feed means;
counter means for determining the standard time that an average length document should take to traverse the feed path;
means for terminating the advancing of said feed means when a document trailing edge has been detected by said sensing means; and
means for determining when both a trailing edge has been detected by said sensing means and said counter means has reached its standard time, whereby said cyclically movable member, in association with said control means, is operative to give a document with which it is in contact, a throughput rate'proportional to its own length if longer than the average length, or if shorter, a throughput rate proportional to that of the average length document.
3. In a mechanism for feeding and separating documents as defined in claim 2 wherein said feed means further includes a drive roller for advancing documents which are positioned downstream from said cyclically movable member, said drive roller further having a speed substantially'greater than the speed of said cyclically movable member thereby imparting a spacing interval between documents to a degree dependent only on this speed differential and the throughput rate for that document.
4. In a mechanism for feeding and separating documents as defined in claim 1 wherein said-pulsing means includes:
means for detecting when said cyclically movable member has actually moved a predetermined distance;
first counter means that is resettable by a signal from said detecting means and operative, as it counts up, to output status signals'indicating when said retarding means must not brake and subsequently in time when said retarding means may conditionally brake said cyclically movable member; and
second counter means resettable by said first counter means for determining the ideal time for the cyclically movable member to move the predetermined distance whereby whenever said second counter means has counted up to its ideal time after said first counter means has outputed its status signal for braking, the cyclically movable member is moving faster than the predetermined speed and braking by said retard means will occur, otherwise, if the ideal time occurs before the status signal for braking then the cyclically movable member is moving too-slow and no braking by said retard means will take place.
5. A control system for document feed and conditioning for serial travel along a guideway comprising:
means fofsuccessively feeding documents into the entrance of a document transport path; means in the transport path downstream from said document feeding means for detecting the trailing edge of a passing document and for producing an electrical signal when such detection occurs;
means for operating the feeding means alternately at on and off" periods of time and such that each on period is approximately equivalent to the transit time for a document to travel the distance from the entrance of the transport path to that point in the transport path when the trailing edge of such document passes said sensing means, said feeding means further operable to engage one side of each successive document and urge each such document down the transport path at a first speed, giving a throughput rate in excess of that desired where the throughput rate is a function of the speed imparted to and the length of the given document;
means for sensing the speed of said feeding means; pressure actuator means positioned opposite to said feeding means and forming a throat therebetween through which the documents are successively advanced, said pressure actuator means being engageable with the side of each document opposite to that engaged by the feeding means and cooperating therewith for applying a pressure both on each such document and the feeding means, said applied pressure causing each such document to be gripped by said feeding means and said actuator means and further causing a retardation in the speed with which the feeding means urges each such document down the guideway; pulsing means operable to transmit a stream of pulses spaced in time to said pressure actuator for causing the same to apply pulsating pressures upon the feeding means and any document passing therebetween; means rendering said pulsing means responsive to said speed sensing means and varying the effective pressure appliedby said pulses in proportion to the speed of said feeding means thereby acting to retard the feeding means down to a second speed giving the desired throughput rate range where the exact throughput rate for a given document is a function of its length; and document advancing means positioned downstream from said trailing edge sensing means for imparting a third speed to each document passing thereby which is substantially greater than said second speed whereby interdocument spacing is achieved by the relatively constant differential between said second speed and said third speed, and the given throughput rate for the subsequent document. 6. In a document control system as defined in claim 5 wherein said feed control means further includes means operative to define a cycle period constituting the sum of each said of period and adjacent 011" period which is the time interval needed to process one document, said cycle period being characterized as synchronous to represent relatively short documents or being characterized as asynchronous to represent relatively long documents depending on the selected cutoff document length differentiating relatively long and short documents from one another,'whereby said cutoff document length determines the boundary between synchronous operation with a constant throughput rate and asynchronous operation with a variable throughput rate.
7. In a document control system as defined in claim 6 including means for interrupting the operation of said feeding means for a finite time interval as the trailing edge of each document in transit through the transport path is sensed by said document trailing edge detecting means resulting in the lowering of the overall average of said second speed thereby establishing the desired throughput rate range and also providing for an absolute minimum interdocumental spacing.
8. A control system for document feed and conditioning for serial travel along a guideway comprising:
means for successively feeding documents into the entrance of a document transport path, said feeding means being further operable to engage one side of each successive document and urge each such document down the guideway at a first speed giving a throughput rate in excess of that desired in the transport path;
means in the transport path downstream from said feeding means for detecting the trailing edge of a passing document and for producing an electrical signal when such detection occurs;
means for controlling the operation of the feeding means alternatively for an on" interval and then and of interval, said on interval approximately equivalent to the transit time for a docu- 1O ing means further operable to engage one side of each successive document and urge each such document down the guideway at a first speed in excess of the desired document throughput rate for the transport path; means in the transport path downstream from said feeding means for detecting the trailing edge of a passing document and for producing an electrical signal when such detection occurs;
means for controlling the operation of the feeding ment to travel the distance from the entrance of the transport path to that point in the transport path when the trailing edge of such document passes said sensing means, the sum of said on interval path is detected by said trailing edge sensing means thereby providing an overall average third speed for the system which is less than said second speed, said third speed serving to define the desired throughput rate range where the exact rate is a function of a document length;
document advancing means positioned downstream from said trailing edge sensing means for imparting a fourth speed to each document passing thereby which is substantially greater than said third speed whereby interdocument spacing is achieved by the relatively constant differential between said third speed and said fourth speed, and the throughput rate of the subsequent document.
means alternately for an on interval and then an off interval, said on interval approximately equivalent to the transit time for a document to travel the distance from the entrance of the transand said off interval constituting a period for the port path to that point in the transport path when gg z g f g g gzs ggg rg gg the trailing edge of sucfh dofument passeslsaiddsensci in means, the sum 0 sai on interva an sai short documents or asynchronous representing relinterva] constituting a period for the process, atwely long documents depenqing on Standard ing of one document, said period can be selected ggz t i g llfg g na si gft g dlfferrsntlzge g fg to be synchronous representing relatively short standard leng%h determines fli ouiici arj ei w in ijocumems or asygchrolziqus repreislemmg g ong documents epen mg on t e cut-0 ocuig 2:5:i ;355 32 83 gggggg ifigg g gggggg ment length selected to differentiate between relathroughput rate where throughput rate is a func- 2& 2 335 333,z g gg ggzg fi lg ifig gfiggg 2532;212:233 lmpaned to and the length of the between synchronous operation with a constant means for sensingthe Speed of Said feeding means throughput rate and asynchronous operation with pressure actuator means positioned opposite to said s gfigfi gg ggzgg gz fi i igg tg gzg 3:
feeding means and forming a throat therebetween len th of the iven docimem p through which the documents are successively adg vanced said p e Ssur e actuator means being means for sensing the speed of said document drive gageable with the side of each document opposite means to that engaged by the feeding means and coopep pressure actuator means positioned opposite to said ating therewith for applying a gripping pressure on 5 feeding means and forming a throat therebetween each such document. through which the documents are successively ada pulsing means operatively coupled to said speed sensvanced i pressilre actuator means bemg ing means and Operable to transmit a Stream of gageable with the side of each document opposite pulses spaced in time to said pressure actuator for engaged by the fedmg m l and cooper' causing the Same to apply alternating gripping and 40 atmg therewith for applying a gripping pressure on releasing pressures on the document driving means F Such document; and and any document passing therebetween, the pulsing means operatively coupled to said speed sensber of said pulses per document varying in propop mg means and operable to transmit a stream of tion of the speed of said feeding means thereby to f- Spaced m to said pressure actuator for brake said feeding means down to a second speed causlrlg the Same to apply ahematmg gnppmg and less than Said fi t Speed; releasing pressures on said feeding means and any means for interrupting the operation of said feeding q Passmg therebetwieni number of means for a finite time interval as the trailing edge 531d Pulses P f Varying proportion to of each document in transit through the transport the Speed of Sald feeding means thereby to brake said feeding means down to a second speed less than said first speed where said second speed defines the desired throughput rate.
10. A control system for document feed and conditioning for serial travel along a guideway comprising:
means for successively feeding documents into the entrance of a document transport path, said feeding means further operable to engage one side of each successive document and urge each such document down the guideway at a first speed giving a throughput rate in excess of that desired in the transport path where the throughput rate is a function of the speed imparted to and the length of the given documents;
9. A control system for document feed and condi- 5 tioning for serial travel along a guideway comprising:
means for successively feeding documents into the entrance of a document transport path, said feedmeans in the transport path downstream from said feeding means for detecting the trailing edge of a passing document and for producing an electrical signal when such detection occurs;