Apparatus and method for controlling a document-handling machine

BACKGROUND

This invention relates generally to the field of handling documents and document-handling machines. More specifically, this invention relates to controlling the timing and motion of documents in a document-handling machine, especially that of mailpieces in a mail-handling machine.

The processing and handling of mailpieces and other documents consumes an enormous amount of human and financial resources, particularly if the processing of the mailpieces is done manually. The processing and handling of mailpieces is performed not only by the Postal. Service, but also by each and every business or other site that communicates via the mail delivery system. Various pieces of mail generated by many departments and individuals within a company must be collected, sorted, addressed, and franked as part of the outgoing mail process. Additionally, incoming mail must be collected and sorted efficiently to ensure that addressees receive it in a minimal amount of time. Because much of the documentation and information being conveyed through the mail system is critical to the success of a business, it is imperative that the processing and handling of both the incoming and outgoing mailpieces be performed efficiently and reliably so as not to negatively affect the functioning of the business.

In view of the above, various automated mail-handling machines have been developed for processing mail (i.e., removing individual pieces of mail from a stack and performing subsequent actions on each individual piece of mail). However, in order for these automatic mail-handling machines to be effective, they must process and handle “mixed mail,” which means sets of intermixed mailpieces of varying size (from postcards to 9″×14″ flats), thickness, and weight. In addition, “mixed mail” also includes “stepped mail” (e.g., an envelope containing an insert which is smaller than the envelope, thereby creating a step in the envelope), tabbed and untabbed mail products, and mailpieces made from different substrates. Thus, the range of types and sizes of mailpieces which must be processed is extremely broad and often requires trade-offs to be made in the design of mixed-mail feeding devices in order to permit effective and reliable processing of a wide variety of mixed mailpieces.

In known mixed-mail handling machines that separate and transport individual pieces of mail away from a stack of mixed mail, the stack of mixed mail is first loaded onto some type of conveying system for subsequent sorting into individual pieces. The stack of mixed mail is advanced as a stack by an external force provided by a stack advance mechanism to, for example, a shingling device. The shingling device applies a force to the lead mailpiece in the stack to initiate the separation of the lead mailpiece from the rest of the stack by shingling it slightly relative to the stack. The shingled mailpieces are then transported downstream to, for example, a separating or singulating device (“singulator”) that completes the separation of the lead mailpiece from the stack so that individual pieces of mail may be transported further downstream for subsequent; processing.

In such a mail-handling machine, the various forces acting on the mailpieces in advancing the stack, shingling the mailpieces, separating the mailpieces, and moving the individual mailpieces downstream often act counterproductively relative to each other. For example, inter-document stack forces exist between each of the mailpieces that are in contact with each other in the stack. These inter-document forces created by the stack advance mechanism, the frictional forces between the documents, and electrostatic forces that may exist between documents, tend to oppose the force required to shear the lead mailpiece from the stack. Additionally, the interaction of the force used to drive the shingled stack toward the singulator and the forces at the singulator can potentially cause a thin mailpiece to be damaged by being buckled as it enters the singulator. Furthermore, in a conventional singulator, there are retard belts and feeder belts that are used to separate the mailpiece from the shingled stack. Both the forces applied by the retard belts and the feeder belts must be sufficient to overcome the inter-document forces previously discussed. However, the friction force generated by the retard belts cannot be, greater than that generated by the feeder belts or the mailpieces will not be effectively separated and fed downstream to the next mail processing device. Moreover, if the feeding force applied to the mailpieces for presenting them to the singulator is too great, “multi-feeding” may occur in which several mailpieces are forced through the singulator without being successfully separated.

Although strong forces seem to be, desirable to accelerate and separate the mailpieces reliably and efficiently, these same strong forces can damage (e.g., buckle) lightweight mailpieces being processed. In response, weak forces may be used to accelerate and separate the mailpieces, but these forces result in poor separation, a lower throughput, and stalling of the mailpieces being processed. The problem is that when both thin mailpieces; which are flimsy and require weak forces to prevent them from being damaged, and thick/heavy mailpieces, which are sturdy and require strong forces for proper separation and feeding, are in the mail stack, stronger stack normal forces may be created due to the thick/heavy mail, requiring stronger nip forces at the singulator; and, these forces may damage the thin mailpieces.

Thus, the apparatus used to separate a stack of mixed mail must take into account the counterproductive nature of the forces acting on the mailpieces and produce an effective force profile acting on the mailpieces throughout their processing cycle to effectively and reliably separate and transport the mailpieces at very high processing speeds (e.g., four mailpieces per second) without physically damaging the mailpieces. However, because the desired force profile acting on a particular mailpiece depends upon the size, thickness, configuration, weight, and substrate of the individual mailpiece being processed, the design of a mixed-mail feeder which can efficiently and reliably process a wide range of different types of mixed mailpieces has been extremely difficult to achieve.

SUMMARY OF THE INVENTION

The present invention provides an apparatus and method for transporting documents along a document feed path from an upstream end to a downstream end. The apparatus includes at least one document-handling subassembly along the document feed path for singulating the documents, controlling gaps between the documents, and/or conveying the documents toward the downstream end; a sensor mounted along the document feed path for sensing the positions of the documents and for generating position signals based on the document positions; and a control apparatus for receiving the position signals and for controlling the velocity and acceleration of the document-handling subassembly so as to regulate the size of the document gaps and to maximize document throughput.

Preferably, the document-handling subassembly includes a singulator. The apparatus may also include a second document-handling subassembly such as an input feeder, between the singulator and the upstream end, for feeding documents along the document feed path, a conveyor belt running between the singulator and the downstream end for conveying the documents downstream along the document feed path after the documents leave the singulator, an aligning area downstream from the singulator, through which the documents are bottom-edge aligned as they are conveyed on the conveyor belt, and a third document-handling subassembly such as a second singulator, placed downstream the aligning area, for further singulating the documents as they are transported from the aligning area. Preferably, the sensor transmits signals to coherently control the velocity and acceleration of the input feeder and singulators so as to control the size of the document gaps and maximize document throughput.

Other document-handling subassemblies include a stack advance mechanism at the upstream end for advancing to the input feeder documents from a document stack at the upstream end, a first output feeder between the singulator and the aligning area for taking the documents from the singulator, and a second output feeder between the second singulator and the downstream end for taking the documents from the second singulator to the downstream end.

Preferably, the sensor is aligned with the beginning of the nip area of the singulator. More preferably, there are at least second through eighth sensors placed downstream the sensor, as follows: the second sensor is aligned after the nip of the singulator; the third and fourth sensors are aligned before and after the nip of the first output feeder, respectively; the fifth and sixth sensors are aligned with the aligning area; the seventh sensor is aligned before the nip-of the second singulator; and the eighth sensor is aligned with the nip of the second output feeder.

Preferably, the sensor and the second sensor can sense when a document is clear of the singulator, so as to start the input feeder and singulator operating. The third sensor can sense when a document is in the first output feeder, so as to stop the first output feeder from operating if the stop flag is set. The fourth sensor can sense when a document is clear of the first output feeder, so as to start the singulator operating unless the stop flag is set. The fourth sensor can also sense when a document is in the first output feeder, so as to set the stop flag in conjunction with the fifth and sixth sensors. The fifth and sixth sensors can sense an unacceptably small document gap, so as to set the stop flag. The seventh sensor can sense an acceptable document gap, so as to clear the stop flag and to accelerate the first output feeder after the stop flag is cleared. The eighth sensor can sense when a document is clear of the second output feeder, so as to cause the second singulator to send a second document into the second output feeder.

Preferably, the aligning area also includes a seventh document-handling subassembly, e.g., a trap, for preventing a document from being conveyed along the document feed path when the gap between the document and a downstream document is unacceptably small and the first output feeder is unable to stop the document.

The apparatus of the present invention can operate at accelerations as low as 0.5 g, enabling documents to be transported with constant motion through the apparatus, thereby maintaining efficient inter-document gaps without using high accelerations.

Additional advantages of the invention will be set forth in the description which follows, and in part Will be obvious from the description, or may be learned by practice of the invention. The advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, in which like reference numerals represent like parts, are incorporated in and constitute a part of the specification. The drawings illustrate presently preferred embodiments of the invention and, together with the general description given above and the detailed description of the preferred embodiments given below, serve to explain the principles of the invention.

FIG. 1

is a schematic top plan view of a mixed-mail feeder of the prior art;

FIG. 2

is an enlarged and detailed top plan view of a singulator of

FIG. 1

;

FIG. 3

is a schematic top plan, view of the mixed-mail feeder of

FIG. 1

incorporating an embodiment of the present invention;

FIG. 4

is a flowchart of a stack advance mechanism control scheme in accordance with an embodiment of the present invention;

FIG. 5

is a flowchart of an input feeder and first singulator control scheme in accordance with an embodiment of the present invention;

FIG. 6

is a flowchart describing the setting of the stop flag in accordance with an embodiment of the present invention;

FIG. 7

is a flowchart describing the clearing of the stop flag in accordance with an embodiment of the present invention;

FIGS. 8

a

-

8

j

are schematic top plan views of the mixed-mail feeder of the present invention showing the various stages of document handling when no stop flag is set, according to an embodiment of the present invention; and

FIGS. 9

a

-

9

j

are schematic top plan views of the mixed-mail feeder of the present invention showing the various stages of document handling when the stop flag is set, according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1

shows a mixed-mail feeder

1

having conventional framework

2

upon which all of the components of the mixed-mail feeder

1

are mounted. Mixed-mail feeder

1

includes a stack advance mechanism

5

having a continuous conveyor belt

7

mounted for conventional rotation about a plurality of pulleys (not shown) in the direction of arrow “A.” Mounted on the conveyor belt

7

in a conventional manner is an upstanding panel

9

which moves with the conveyor

7

in the direction of arrow “A.” During operation, a stack

11

of mixed mail is placed on the conveyor belt

7

and rests against the panel

9

. Mixed-mail stack

11

includes a lead mailpiece

13

and a second mailpiece

15

. Thus, as conveyor belt

7

begins to move, mixed-mail stack

11

is directed toward an input feeder

17

(also called an “input feed structure” or “nudger”). Input feeder

17

includes a belt

18

which is driven into rotation about a series of pulleys

20

, at least one of which is a driven pulley. Accordingly, as stack advance mechanism

5

forces lead mailpiece

13

into contact with belt

18

, lead mailpiece

13

is laterally moved away from mixed-mail stack

11

. Additionally, a driven belt

19

, which makes contact with the bottom edge of lead mailpiece

13

, also assists in moving lead mailpiece

13

downstream past a guide mechanism

21

and toward a first document singulator

23

(or “singulating apparatus” or “separator”). As shown, the combination of stack advance mechanism

5

, input feeder

17

, and guide plate

21

helps to present the mailpieces-which are removed from mixed-mail stack

11

into first singulator

23

in a shingled manner as is more clearly shown in FIG.

2

.

First singulator

23

operates to separate lead mailpiece

13

from the remaining mixed-mail stack

11

, so that only individual mailpieces are presented to first output feeder

25

for ultimate processing downstream to a processing station

26

, which performs some type of operation (e.g., metering, scanning, etc.) on each individual mailpiece. First singulator

23

includes a feed assembly

49

for feeding each individual document of the stack

43

of shingled mailpieces downstream along a path of travel

51

. First singulator

23

further includes a retard assembly

53

for feeding each next successive document of shingled mailpiece stack

43

, upstream relative to path of travel

51

. That is, feed assembly

49

interacts with lead mailpiece

13

to move it downstream along path of travel

51

, while retard assembly

53

causes the remainder of the documents in shingled mailpiece stack

43

to be moved slightly upstream. Springs

111

and

115

allow the belts and pulleys that make up retard assembly

53

to resist lateral movement due to downstream travel of shingled mailpiece stack

43

. The forces respectively exerted by feed assembly

49

on lead mailpiece

13

and retard assembly

53

on the remaining documents in the stack are sufficient to overcome the inter-document force between the lead mailpiece and the next successive document in the stack. Thus, when first singulator

23

operates as intended, only one document at a time leaves first singulator

23

for presentation to first output feeder

25

. First singulator

23

is further described in U.S. Pat. No. 6,135,441, assigned to the assignee of this invention, the disclosure of which is hereby incorporated by reference.

From first singulator

23

, the separated individual mailpiece is then fed to first output feeder

25

. First output feeder

25

(or “output feed structure”) includes “take-away” rollers

27

,

29

which receive the mailpiece as it exits first singulator

23

and help to transport the mailpiece downstream. Although first output feeder

25

is shown in

FIG. 1

as a roller pair, it could include a belt pair instead of the rollers. The take-away rollers comprise a drive roller

29

and an idler roller

27

. Take-away idler roller

27

is spring loaded by spring

30

and is moveable toward and away from take-away drive roller

29

to accommodate different mailpiece thicknesses. First output feeder

25

transports the mailpiece to the next stage, aligner

31

.

Aligner

31

(also known as a “deskew area” or a “buffer station”), consisting of two driven belt structures

33

,

35

, helps to buffer the individual mailpieces to ensure that they are aligned on their bottom edges prior to transport downstream. Acting on the bottom edges of the mailpieces is a driven-transport belt

42

, which transports the mailpieces from first output feeder

25

through buffer station

31

to processing station

26

. Preferably, belt structures

33

,

35

may be separated from each other on each side of the mailpiece feed path

51

by a distance of approximately 1.5 inches. This spacing allows most multi-feeds which leave first singulator

23

to be transported through aligner

31

without any large inter-document forces existing between the mailpieces (such as frictional forces), because no significant normal feed force is present when the mailpieces are fed by transport belt

42

. Additionally, it has been found that by using driven belts

33

,

35

, mailpieces which curl up in aligner

31

are still transported out of aligner

31

. In an alternative embodiment, driven belts

33

,

35

could be replaced with fixed-wall structures such as those described in U.S. patent application Ser. No. 09/411,064, assigned to the assignee of this invention, the disclosure of which is hereby incorporated by reference. In such an embodiment, the distance between the walls may be different from the distance disclosed above, based on the maximum height and thickness of the mailpieces handled by the mixed-mail feeder and the height of the walls lining aligner

31

. In addition, antistatic brushes may be mounted onto the fixed-wall structures to help prevent lightweight, static-prone mailpieces, such as envelopes, postcards, and mailpieces wrapped in TYVEK® (manufactured by DuPont), from clinging to the walls.

In addition, aligner

31

could also include a trap subsystem

100

(shown in FIG.

3

), which controls the gap size between mailpieces. Gaps are important because the mail-handling machine may need time for processing that occurs downstream in processing station

26

, such as optical character recognition (OCR) processing. Additionally, proper gap size affects throughput of the mail-handling machine and is also helpful in a situation in which there is a multi-feed going into a second document singulator

39

, as described below. Trap

100

allows transport belt

42

to remain in constant motion while an inter-piece gap is being maintained or lengthened, instead of attempting to achieve the gap by stopping and starting transport belt

42

, which would stop all of the mailpieces on the belt instead of just the mailpieces between which a larger gap is desired.

FIG. 3

shows trap

100

comprising two trap levers

101

,

103

(shown in the open, non-trapping position) which are actuated in order to grab a mailpiece as it moves through aligner

31

.

From aligner

31

, the mailpieces are transported on transport belt

42

past a second guide plate

37

and into second singulator

39

. This singulator is shown in

FIG. 1

to have the identical structure as first singulator

23

, where feed assembly

50

and retard assembly

54

of second singulator are equivalent to feed assembly

49

and retard assembly

53

of first singulator

23

. The feed and retard assemblies of second singulator

39

are shown in

FIG. 1

as being positioned along feed path

51

with the same orientation as the feed and retard assemblies of first singulator

23

. However, in various embodiments of the mixed-mail feeder, the feed and retard assemblies of first singulator

23

could be disposed on opposite sides of feed path

51

as compared to the corresponding structure in second singulator

39

(and second guide plate

37

would also be disposed on the opposite side of feed path

51

). Such opposite disposition is only a desired configuration, however, if the mixed-mail feeder has not already sorted a mail stack at least once. In that case, oppositely disposed singulators could disrupt the sorted order of the mail.

Furthermore, second singulator

39

may not appear in some embodiments. It is preferable, however, to include second singulator

39

because the use of a redundant singulator improves the reliability of separating individual documents from each other. In the case where a multi-feed does pass through first singulator

23

, it is likely that second singulator

39

will effectively separate the documents, of the multi-feed. Additionally, because of the use of second singulator

39

, the singulating nip force at first singulator

23

(as well as at second singulator

39

) applied by each of the springs

111

,

115

can be significantly reduced, thereby preventing damage to thin mailpieces being processed through singulators

23

and

39

. In other words, because second singulator

39

provides a second opportunity to separate any multi-feeds that may occur, problems associated with reducing the nip force in a single singulator structure are largely eliminated.

Subsequent to passing through second singulator

39

, the individual mailpieces are transported into a second output feeder

41

(identical to first output feeder

25

) which acts on the mailpieces together with transport belt

42

to transport the individual mailpieces to processing station

26

.

The mixed-mail feeder shown in FIG.

1

and described above, however, may still encounter some transport problems. It was discussed above, with respect to aligner

31

, that trap subsystem

100

could be incorporated to trap documents in order to control gap size between mailpieces and to improve throughput of the mail-handling machine. One method of enforcing gap is described in aforementioned U.S. patent application Ser. No. 09/411,064. That reference enforces gap by adding a number of sensors mounted along feed path

51

. The sensors detect the positions of the mailpieces and actuate trap levers

101

,

103

any time too small a gap exists between mailpieces which can not be widened by some other upstream document-handling subassembly such as take-away rollers

27

,

29

of first output feeder

25

. The trap subsystem is actuated using an electromagnetic solenoid actuator controlled by a microprocessor controller.

Gap size can also be controlled in other ways. U.S. patent application Ser. No. 09/411,064 also discloses an alternative embodiment to the trap subsystem. That alternative embodiment uses upstream and downstream transport belts, with a small space between them, instead of a single transport belt

42

. The upstream belt begins at first output feeder

25

and ends in the middle of aligner

31

. The downstream belt begins in the middle of aligner

31

, slightly downstream from the end of the upstream belt, and continues to processing station

26

. When a sensor aligned with second singulator

39

senses a multi-feed in that singulator, and a second sensor aligned with output feeder

41

senses a mailpiece in that output feeder, the upstream belt is stopped which allows the downstream belt to clear the multi-feeds or enlarge the document gaps.

Nevertheless, the gap control mechanisms disclosed in U.S. patent application Ser. No. 09/411,064 only control discrete parts of the mixed-mail feeder. What is needed is a more comprehensive and coherent control system to better enforce gap size and to increase document throughput.

The present invention accomplishes these tasks by using sensors mounted along document feed path

51

to coherently control the velocity and acceleration of stack advance mechanism

5

, input feeder

17

, first singulator feed assembly

49

, first output feeder

25

, and second singulator feed assembly

50

. Preferably, the present invention also controls the actuation of trap subsystem

100

.

FIG. 3

is a schematic top plan view of the mixed-mail feeder of

FIG. 1

incorporating an embodiment of the present invention. In addition to the features described with respect to

FIG. 1

,

FIG. 3

also includes light sensors

201

-

241

and

251

, light transmitters

202

-

242

, microprocessor controller.

200

, control signal bus

260

, and sensor signal bus

270

. Sensors

201

-

241

and transmitters

202

-

242

are mounted along document feed path

51

. Each sensor may be, for example, a photoelectric sensor for detecting light. As shown in

FIG. 3

, each odd sensor

201

-

241

may be paired with an even transmitter

202

-

242

forming a detection pair. Light may be transmitted from the even transmitter to the odd sensor. An absence of light detected by the sensor (i.e., the sensor is blocked) indicates that a mailpiece is on transport belt

42

in the area of that sensor, and the presence of light detected by the sensor indicates that there is no mailpiece in the area of the sensor. The use of detection pairs to indicate the presence or absence of a mailpiece between the detection pair is only one sensor configuration. Other types of sensors and detection configurations can be used. For instance, sensor

251

does not have a transmitter associated with it, yet it is able to detect the position of, input feeder

17

by sensing the presence or absence of light caused by the input feeder's movement during document handling.

FIG. 3

depicts stack advance mechanism

5

and the first and second singulators in the same orientation with respect to each other as is shown in FIG.

1

. However, in some embodiments of the present invention, it is more advantageous (for downstream processing reasons, for example) for the stack advance mechanism to be placed toward the bottom of

FIG. 3

, with first and second singulators also oriented in the opposite position from that shown in

FIG. 3

[i.e., first singulator feed assembly

49

is positioned “above” (more toward the top of

FIG. 3

than) first singulator retard assembly

53

]. In those cases, mail is fed in the direction opposite to that shown by arrow “A.” In either case, however, the present invention operates the same.

The position signals generated by sensors

201

-

241

,

251

are transmitted to microprocessor controller

200

using sensor signal bus

270

. Microprocessor

200

receives the position signals and coherently controls the velocity and acceleration of various structures of mixed-mail feeder

1

according to a protocol described below. The control signals generated by microprocessor controller

200

are transmitted to the various document handling structures using control signal bus

260

.

An objective of the present invention is to transport as many mailpieces as possible without jamming, creating multi-feeds, or unnecessarily accelerating or decelerating the mailpieces. The sensors and the various document-handling subassemblies, such as stack advance mechanism

5

, input feeder

17

, first and second singulator feed assemblies

49

,

50

, first and second output feeders

25

,

41

, and aligner

31

, operate coherently as follows.

Sensor

251

detects the position of input feeder

17

so as to control stack advance mechanism

5

. As previously described with respect to

FIG. 1

, conveyor belt

7

begins to move, directing mixed-mail stack

11

toward input feeder

17

, which is deflected in the direction “A.” The more force with which stack advance mechanism

5

pushes, the more deflection of input feeder

17

, and the more normal inter-document force is generated in mixed-mail stack

11

. Sensor

251

is positioned with respect to input feeder

17

so that when sensor

251

is triggered, input feeder

17

is receiving too great an amount of force from stack advance mechanism

5

. In that case, sensor

251

generates and transmits to microprocessor

200

a signal that the force on input feeder

17

is too great. In a preferred embodiment, there is also a tilt sensor (not shown) in input feeder

17

which senses the position of the input feeder. This sensor generates and transmits to microprocessor

200

a signal that input feeder

17

is tilted too much due to too much force from stack advance mechanism

5

. In response to sensor

251

and the tilt sensor, microprocessor

200

transmits a control signal to stack advance mechanism

5

to stop advancing mixed-mail stack

11

. Stopping the stack advance mechanism also permits the input feeder to be activated (when the proper situation arises downstream, as will be discussed below); when the stack advance mechanism is operating, the input feeder will not operate. The stack advance mechanism will remain stopped so long as both sensor

251

and the tilt sensor are triggered. Once either of these sensors is no longer triggered, because, for example, one or more mailpieces in mixed-mail stack

11

has been transported downstream by input feeder

17

, thus-reducing the size of mixed-mail stack

11

or tilt of input feeder

17

, microprocessor controller

200

transmits a control signal to stack advance mechanism

5

to resume operation. In a preferred embodiment, when stack advance mechanism

5

is accelerated by control signals from microprocessor controller

200

, the acceleration is 1.0 g. Conversely, when stack advance mechanism

5

is decelerated, the deceleration is 0.115 g. Preferably, this acceleration and deceleration result in the stack advance mechanism moving at a velocity of 3.56 inches per second (“ips”) (˜9.04 cm per second (“cps”)).

This protocol is illustrated in the flowchart in FIG.

4

. Step

410

asks whether the “stop flag” is set. The stop flag and conditions for its setting will be discussed below. For the time being, assume that the stop flag is not set. Step

420

then asks whether sensor

251

is triggered by input feeder

17

. If not, step

425

runs (or keeps running) stack advance mechanism

5

. This loop of steps

420

,

425

, and

410

continues until sensor

251

is triggered by the position of input feeder

17

. At that time, step

430

asks whether the tilt sensor in input feeder

17

is triggered. If not, step

425

runs (or continues to run) stack advance mechanism

5

. The flowchart then loops back to determine if sensor

251

is still triggered by input feeder

17

. Going back to step

430

, if the tilt sensor in input feeder

17

is triggered, there is too much force on input feeder

17

and step

415

stops stack advance mechanism

5

and then loops back to steps

410

and

420

.

From input feeder

17

, a mailpiece is transported to first singulator

23

. Sensors

201

,

203

detect the presence or absence of a mailpiece in first singulator

23

so as to control input feeder

17

. Input feeder

17

transports mailpieces

13

,

15

from mixed-mail stack

11

laterally to first singulator

23

via belt

18

, possibly resulting in a stack

43

of shingled mailpieces in first singulator

23

, as is shown in FIG.

2

. Sensor

201

is aligned with the beginning of the nip area

105

in first singulator

23

and sensor

203

is aligned with the end of nip area

105

in first singulator

23

. Preferably, this results in sensor

201

being placed 48 mm upstream the end of nip area

105

; and sensor

203

being placed 9 mm downstream the end of nip area

105

.

When light transmitted from transmitter

204

is blocked from being detected by sensor

203

because of a mailpiece blocking the transmission path, sensor

203

generates and transmits to microprocessor

200

a signal that first singulator

23

is full. In response, microprocessor

200

transmits a control signal to input feeder

17

to stop advancing mailpieces into first singulator

23

. Although one way to achieve this result (i.e., preventing mailpieces from entering first singulator

23

) is by stopping belt

18

, it is preferable to leave belt

18

running at a constant speed and to stop driven nudger rollers in input feeder

17

(not shown in

FIGS. 1

or

3

), which may be mounted on a wall parallel to upstanding panel

9

, from operating. Nudger rollers are further described in U.S. Pat. No. 5,971,391, assigned to the assignee of this invention, the disclosure of which is hereby incorporated by reference.

Sensors

201

and

203

together detect when first singulator

23

is clear of mailpieces (sensor

203

detects a trailing edge of a mailpiece). When these two sensors are thus clear, first singulator

23

is deemed to be completely empty. Sensors

201

and

203

generate and transmit signals to microprocessor

200

, which, when downstream document-handling subassemblies are in operation (exceptions to which will be discussed shortly), then transmits a control signal to input feeder

17

to resume advancing mailpieces into first singulator

23

. In addition, in order to preserve throughput, first singulator

23

is triggered by operation of input feeder

17

. (Although this discussion describes the triggering of first singulator

23

, it is more precise to describe in a preferred embodiment that first singulator feed assembly

49

is triggered by operation of input feeder

17

, because first singulator retard assembly

53

is preferably continuously running at a constant backward velocity, preferably at 4 ips (˜10.2 cps).) Alternatively, even if input feeder

17

has not been restarted because either sensor

201

or

203

is blocked, first singulator feed assembly

49

can be restarted to transport a mailpiece toward first output feeder

25

if a downstream mailpiece has completely cleared first output feeder

25

and sensor

213

.

Using this scheme, mailpieces are efficiently fed. In a preferred embodiment, when the driven nudger rollers of input feeder

17

are accelerated by control signals from microprocessor controller

200

, the acceleration is 0.5 g. Conversely, when the driven nudger rollers of input feeder

17

are decelerated, they decelerate to a stop. Preferably, this acceleration results in the driven nudger rollers operating at a velocity of 37.4 ips (˜95 cps). When triggered, first singulator feed assembly

49

also accelerates at 0.5 g, but operates at a final velocity of 42 ips (˜107 cps). Even though the accelerations of the two document-handling subassemblies when approaching the final velocities are the same, the velocity of the first singulator feed assembly is generally greater than that of the input feeder so that there is a tension between the first singulator feed assembly and the input feeder to pull the document downstream.

This protocol is illustrated in the flowchart in FIG.

5

. Again, as with the discussion of

FIG. 4

, the first step, step

510

, asks whether the stop flag is set. The setting of the stop flag will be discussed below. For the present discussion, assume that the stop flag is not set and has not previously been set. Step

520

asks whether sensor

203

is blocked by a mailpiece in first singulator

23

. If so, step

525

stops the driven nudger rollers of input feeder

17

. However, as shown by steps

530

,

535

, and

537

, first singulator feed assembly

49

is only stopped if sensor

213

is also blocked. If the answer to step

520

is that sensor

203

is not blocked, step

540

asks whether sensor

201

is blocked.

If sensor

201

is not blocked, first singulator feed assembly

49

runs in step,

565

and driven nudger rollers run in step

567

(assuming the previous stop flag is not set, see step

560

), so long as downstream document-handling subassemblies are operating (i.e., the stop flag is not set, discussed below). If the answer to step

540

is that sensor

201

is blocked, step

550

asks whether sensor

213

is blocked. If not, first singulator feed assembly

49

runs (step

552

) and the driven nudger rollers continue to run, if they are running, or do not start, if they are stopped. If sensor

213

is blocked, both the driven nudger rollers and first singulator feed assembly

49

stop (steps

555

,

557

).

From first singulator

23

, a mailpiece is transported to first output feeder

25

. Sensors.

211

,

213

detect the presence or absence of, a mailpiece in that output feeder. These sensors operate in conjunction with sensors

221

-

227

in aligner

31

and sensor

231

near the entrance to second singulator

39

so as to primarily control first output feeder

25

, trap subsystem

100

, and feed assembly

50

of second singulator

39

, and also to control stack advance mechanism

5

, input feeder

17

, and first singulator feed assembly

49

. A key aspect of this control scheme is the setting of the stop flag (alternatively termed issuance of “stop commands”). The stop flag is set in the event the gap between mailpieces in aligner

31

becomes unacceptably small, as may happen if a multi-feed has advanced to second singulator

39

. Preferably, the stop flag is set when there is not at least a two-sensor clearance between mailpieces. In other words, if fewer than two adjacent sensors

221

,

223

,

225

,

227

,

231

are blocked by consecutive mailpieces, then the stop flag is set.

Preferably, sensors

211

,

213

are placed 20 mm on either side of the nip of first output feeder

25

. Sensors

221

,

223

,

225

,

227

, and

231

are preferably evenly spaced through the aligner at 65 mm intervals.

The setting of the stop flag increases the gap between the mailpieces by preventing upstream mailpieces from moving downstream. This is preferably accomplished by stopping rollers

27

,

29

of first output feeder

25

at the correct moment and may be supplemented by actuating trap subsystem

100

within aligner

31

. Once the stop flag is cleared, a protocol is required to restart the various document-handling subassemblies to keep from losing control over the gap.

FIG. 6

illustrates the “two-sensor look-ahead” protocol for setting the stop flag. In step

610

, sensor

213

looks for the leading edge (“LE”) of a mailpiece. If the LE is detected, step

620

then looks ahead to the next two sensors,

221

and

223

, and asks if either of those is blocked. If so, there is less than a two-sensor gap between the mailpiece whose leading edge is at sensor

213

and a downstream mailpiece. In that case, step

625

sets the stop flag.

If, in step

610

, no leading edge is detected at sensor

213

or, in step

620

, neither

221

nor

223

is blocked, the protocol proceeds to step

630

to look for a leading edge at sensor

221

. If the leading edge is detected at sensor

221

, step

640

then looks ahead to the next two sensors,

223

and

225

, and asks if either of those is blocked. If so, there is less than a two-sensor gap between the mailpiece whose leading edge is at sensor

221

and a mailpiece further downstrearm. Again, in that case, step

625

sets the stop flag. If, in step

630

, no leading edge is detected at sensor

221

or, in step

640

, neither

223

nor

225

is blocked, the protocol proceeds to step

650

to look for a leading edge at sensor

223

. If the leading edge is detected at sensor

223

, step

660

then looks ahead to the next two sensors,

225

and

227

, and asks if either of those is blocked. If so, there is less than a two-sensor gap between the mailpiece whose leading edge is at sensor

223

and a mailpiece further downstream. Step

625

sets the stop flag if that is the case.

If, in step

650

, no leading edge is detected at sensor

223

or, in step

660

, neither

225

nor

227

is blocked, the protocol proceeds to step

670

to look for a leading edge at sensor

225

. If the leading edge is detected at sensor

225

, step

680

then looks ahead to the next two sensors,

227

and

231

(which is adjacent second singulator

39

), and asks if either of those is blocked. If so, there is less than a two-sensor gap between the mailpiece whose leading edge is at sensor

225

and a mailpiece further downstream. In such a case, step

625

sets the stop flag. If, in step

670

, no leading edge is detected at sensor

225

or, in step

680

, neither

227

nor

231

is blocked, the protocol loops-back to step

610

to look for a leading edge at sensor

213

. This protocol illustrated in

FIG. 6

is constantly. performed.

Once the stop flag is set, the protocol illustrated in the flowchart in

FIG. 7

takes over in order to determine when to clear the stop flag. Step

710

constantly watches for the setting of the stop flag. When the stop flag is set, step

712

stops first output feeder

25

(i.e., stops take-away rollers

27

,

29

), step

714

stops first singulator feed assembly

49

, step

716

stops the driven nudger rollers in input feeder

17

, and step

718

stops stack advance mechanism

5

. Note that the combination of steps

710

and

718

is equivalent to steps

410

and

415

in

FIG. 4

, and the combination of steps

710

,

714

, and

716

is equivalent to steps

510

,

515

, and

537

in FIG.

5

.

After these four document-handling subassemblies stop in steps

712

-

718

, step

720

looks to see whether sensor

211

is blocked, i.e., whether there is a mailpiece in first output feeder

25

. As discussed above, one of the triggers for the stop flag to be set is that there is a leading edge at sensor

213

and less than a two-sensor gap between the document at sensor

213

and the next downstream mailpiece (steps

610

and

620

). If this is the condition that caused the stop flag to set, then the mailpiece is still likely to be in first output feeder

25

and sensor

211

will be blocked. In that case, the stopping of first output feeder

25

and take-away rollers

27

,

29

will stop the mailpiece from proceeding into aligner

31

. For longer mailpieces, it is also possible for the leading edge to be at sensors

221

,

223

, or

225

, and for the tail portion of the mailpiece to still be in first output feeder

25

. In these cases also, sensor

211

will be blocked and the stopping of first output feeder

25

and take-away rollers

27

,

29

will stop the mailpiece from proceeding into aligner

31

.

If the stop flag was set because the leading edge of the mailpiece was at sensors

221

,

223

, or

225

(steps

630

,

650

, and

670

) and there was less than a two-sensor gap, it is possible, (for smaller mailpieces) for the mailpiece to have cleared first output feeder

25

. In that case, the answer to step

720

is “no” (sensor

211

is not blocked), and the stopping of first output feeder

25

cannot stop the mailpiece from proceeding downstream. In that situation, the trap must be actuated, as indicated by step

725

.

Once the response to step

720

is resolved, the mail-handling machine looks to clear the stop flag to resume mail flow from the upstream document-handling subassemblies. Because a leading cause of the stop flag being set is a multi-feed that has advanced to second singulator

39

, causing documents to back up in aligner

31

and reducing the inter-piece gaps, second singulator

39

has to clear before the upstream mailpieces are allowed to move. However, in order for feed assembly

50

of second singulator

39

to run, second output feeder

41

must be clear. These conditions are set forth beginning with step

730

.

Step

730

asks whether sensor

241

, which is preferably adjacent the nip of second output feeder

41

, is blocked. If so, second output feeder

41

is transporting a mailpiece to processing station

26

and directs step

735

to stop second singulator feed assembly

50

(or cause it to remain stopped). So long as sensor

241

is blocked, second singulator feed assembly

50

will not move. Once the mailpiece clears second output feeder

41

and sensor

241

, step

737

starts second singulator feed assembly

50

. Step

740

then asks whether sensor

231

, which is adjacent the entrance to second singulator

39

, is blocked. If so, second singulator

39

still has at least one document in it and the upstream documents should not be sent downstream until the second singulator clears. This condition is indicated by the loop around step

740

. Once second singulator

39

is clear, sensor

231

will be unblocked, allowing step

745

to open the trap (if it had been actuated) and step

747

to start the first output feeder. Step

750

then clears the stop flag.

After a stop flag is cleared, first singulator feed assembly

49

is not immediately restarted in order to enforce the gap created by the setting of the stop flag. Thus, if a mailpiece is in first output feeder

25

during the time the stop flag was set, an immediate starting of first singulator feed assembly

49

would result in too small a gap between the document in first output feeder

25

and the next document leaving first singulator

23

, thereby possibly causing the stop flag to be set again when the.document leaving first singulator

23

arrives at first output feeder

25

. To minimize this possibility, a second flag (“previous stop flag”) is set in step

755

after the stop flag is cleared. Returning to

FIG. 5

, once the stop flag is clear, step

510

returns “no.” If both sensors

203

and

201

are unblocked (steps

520

and

540

), first singulator

23

is clear. Step

560

then asks whether the previous stop flag is set. As mentioned before with respect to

FIG. 5

, if the previous stop flag is not set, first singulator feed assembly

49

is set to run in step

565

and the nudger rollers of input feeder

17

can start to run in step

567

. If the previous stop flag is set, the first singulator feed assembly cannot run until a trailing edge passes sensor

221

adjacent the beginning of aligner

31

. Step

570

accomplishes this task. If the trailing edge of the mailpiece previously stopped in first output feeder

25

or in trap

100

has not yet passed sensor

221

, the flowchart in

FIG. 5

loops back to the beginning (step

510

) to confirm that first singulator

23

is still clear before testing again whether sensor

221

is clear. Once the trailing edge passes sensor

221

, step

575

clears the previous stop flag and starts the first singulator feed assembly and driven nudger rollers in steps

565

and

567

.

FIGS. 8 and 9

illustrate the general operation of an embodiment of the present invention. Shown are three mailpieces, lead mailpiece

13

, second mailpiece

15

, and third mailpiece

16

, each of which has a leading edge (“LE”) and a trailing edge (“TE”).

FIG. 8

illustrates normal operation when there are no multi-feeds through first singulator

23

.

FIG. 8

a

is a snapshot of the mailpiece-handling protocol at a first increment in time. Each of the mailpieces

13

,

15

,

16

also includes an arrow

13

a

,

15

a

,

16

a

, respectively, denoting that the mailpiece is currently moving in the direction of the arrow. Mailpieces

13

,

15

,

16

are shown in stack advance mechanism

5

and input feeder

17

, with driven nudger rollers in input feeder

17

preferably accelerating at 0.5 g to 37.4 ips and first singulator feed assembly

49

preferably accelerating at 0.5 g to 42 ips.

FIG. 8

b

shows the next increment of time in which all three mailpieces have advanced to first singulator

23

, and mailpiece

13

has been driven into nip

105

, leaving mailpieces

15

and

16

shingled behind. When the leading edge of mailpiece

13

(“LE

13

”) is sensed by sensor

203

, the driven nudger rollers of input feeder

17

are decelerated to a stop, to prevent mail from being overstuffed into the first singulator (

FIG. 5

, steps

520

&

525

). Mailpieces

15

,

16

are stopped by first singulator retard assembly

53

, and each of mailpieces

15

,

16

also includes an X

15

b

,

16

b

, respectively, denoting that the mailpiece is currently stopped. Input feeder

17

also includes an X

17

b

to indicate that the nudger rollers have stopped.

When LE

13

is sensed by sensor

213

(at the exit of first output feeder

25

) in

FIG. 8

c

, first singulator feed assembly

49

stops to allow first output feeder

25

to strip mailpiece

13

from first singulator

23

(steps

530

&

537

). X's

49

b

indicate that first singulator feed assembly

49

has stopped.

When the trailing edge of mailpiece

13

(“TE

13

”) passes sensor

203

, and sensors

201

and

203

are clear, the driven nudger rollers and first singulator feed assembly

49

will accelerate up to speed (steps

565

&

567

) in order to retain adequate throughput by keeping first singulator

23

full. When the leading edge of mailpiece

15

(“LE

15

”) passes sensor

201

, if sensor

213

is blocked (by mailpiece

13

), the driven nudger rollers and first singulator feed assembly

49

stop (steps

555

&

557

). Once TE

13

passes sensor

213

, first singulator feed assembly

49

runs (step

552

) and the driven nudger rollers remain stopped, as shown in

FIG. 8

d

. Once mailpiece

13

is in aligner

31

, mailpiece

13

is driven by under-riding transport belt

42

. Preferably, transport belt

42

runs continuously at a constant velocity of 42 ips (˜107 cps).

When LE

15

reaches sensor

203

, the driven nudger rollers remain stopped (step

525

), but, because sensor

213

is not blocked, first singulator feed assembly

49

will keep going (step

535

). Then, as shown in

FIG. 8

e

, once LE

15

reaches sensor

213

, because sensor

203

is blocked, first singulator feed

5

assembly

49

stops (step

537

) and first output feeder

25

strips mailpiece

15

from first singulator

23

. LE

15

passing sensor

213

also starts the two-sensor look-ahead protocol, but because both sensors

221

and

223

are clear, no stop condition is met (steps

610

&

620

).

FIG. 8

f

shows the trailing edge of mailpiece

15

(“TE

15

”) passing sensor

203

. When sensors

201

and

203

are clear, the driven nudger rollers and first singulator feed assembly

49

are accelerated up to speed (steps

565

&

567

).

FIG. 8

f

also shows that the stop condition is again not met when LE

15

passes sensor,

221

, because sensors

223

and

225

are clear (steps

630

&

640

). The aligner indirectly drives mailpiece

13

into second singulator

39

(

FIG. 8

g

), the feed assembly of which was accelerated (preferably at 2.0 g) up to velocity (preferably 35.4 ips (˜90 cps)) when mixed-mail feeder

1

was turned on.

When the leading edge of mailpiece

16

(“LE

16

”) passes sensor

201

, if sensor

213

is blocked (by mailpiece

15

), the driven nudger rollers and first singulator feed assembly

49

stop (steps

555

&

557

), as shown in

FIG. 8

g

.

FIG. 8

g

also shows that the stop condition is again not met when LE

15

passes sensor

223

, because sensors

225

and

227

are clear (steps

650

&

660

).

Once TE

15

passes sensor

213

, first singulator feed assembly

49

runs (step

552

) because sensor

203

is clear, but the driven nudger rollers remain stopped. When LE

16

reaches sensor

203

, the driven nudger rollers remain stopped (step

525

), and, because sensor

213

is not blocked, first singulator feed assembly

49

will keep running (step

535

). Then, as shown in

FIG. 8

h

, once LE

16

reaches sensor

213

, because sensor

203

is blocked, first singulator feed assembly

49

stops (step

537

) and first output feeder

25

strips mailpiece

16

from first singulator

23

.

FIG. 8

h

also shows sensor

241

blocked by mailpiece

13

, which causes second singulator feed assembly

50

to stop, as indicated by X

50

b

. Second output feeder

41

strips mailpiece

13

from second singulator

39

. Preferably, second output feeder

41

runs constantly at 35.4 ips (˜90 cps).

FIG. 8

i

shows the trailing edge of mailpiece

16

(“TE

16

”) passing sensor

203

. When sensors

201

and

203

are clear, the driven nudger rollers and first singulator feed assembly

49

are accelerated up to speed (steps

565

&

567

).

FIG. 8

i

also shows TE

13

passing sensor

241

toward processing station

26

. This re-accelerates second singulator feed assembly

50

at 2.0 g, preferably, so that second singulator feed assembly

50

is running at 35.4 ips by the time mailpiece

15

reaches second singulator

39

.

When LE

15

passes sensor

241

, second singulator feed assembly

50

stops, as shown in-

FIGURE 8

j

. Mailpiece

16

continues to be transported through aligner

31

toward second singulator

39

. When TE

15

passes sensor

241

toward processing station

26

, second singulator feed assembly

50

will accelerate, driving mailpiece

16

through to second output feeder

41

and on to processing station

26

.

FIG. 9

illustrates operation when a stop condition is activated. Such a condition might occur if mailpieces

13

and

15

enter aligner

31

together (i.e., a multi-feed).

FIG. 9

a

shows mailpieces

13

and

15

multi-feeding in first singulator

23

, where the driven nudger rollers have just stopped when LE

13

passed sensor

203

(step

525

).

When LE

13

is sensed by sensor

213

, first singulator feed assembly

49

stops (steps

530

&

537

). When TE

15

passes sensor

203

, and sensors

201

and

203

are clear, the driven nudger rollers and first singulator feed assembly

49

will accelerate up to speed (steps

565

&

567

). When LE

16

passes sensor

201

, if sensor

213

is blocked (by mailpieces

13

and

15

), the driven nudger rollers and first singulator feed assembly

49

stop (steps

555

&

557

), as shown in

FIG. 9

b.

Once TE

15

passes sensor

213

, first singulator feed assembly

49

runs (step

552

), but the driven nudger rollers remain stopped. Once mailpieces

13

and

15

are in aligner

31

, mailpieces

13

and

15

are driven by under-riding transport belt

42

. When LE

16

reaches sensor

203

, the driven nudger rollers remain stopped (step

525

), and, because sensor

213

is not blocked, first singulator feed assembly

49

will keep running (step

535

). Then, as shown in

FIG. 9

c

, once LE

16

reaches sensor

213

, because sensor

203

is blocked, first singulator feed assembly

49

stops (step

537

) and first output feeder

25

strips mailpiece

16

from first singulator

23

. LE

16

passing sensor

213

also starts the two-sensor look-ahead protocol, but because both sensors

221

and

223

are clear, no stop condition is met (steps

610

&

620

).

FIG. 9

d

shows TE

16

passing sensor

203

. When sensors

201

and

203

are clear, the driven nudger rollers and first singulator feed assembly

49

are accelerated (steps

565

&

567

).

FIG. 9

d

also shows that the stop condition is again not met when LE

16

passes sensor

221

, because sensors

223

and

225

are clear (steps

630

&

640

). Multi-feed

13

/

15

is shown entering second singulator

39

.

FIG. 9

e

shows TE

16

just before it passes sensor

213

. Driven nudger rollers and first singulator feed assembly

49

are still running because sensors

201

and

203

are clear. Second singulator

39

is separating mailpiece

13

from mailpiece

15

, as mailpiece

16

is being transported into aligner

31

. The two-sensor look-ahead sees LE

16

at sensor

223

and checks to see if sensors

225

and

227

are clear (steps

650

&

660

). Because sensor

227

is not clear, the stop flag is set (step

625

).

Once the stop flag is set,

FIG. 9

f

shows that first output feeder

25

is stopped (step

712

), indicated by X

25

b

, first singulator feed assembly

49

is stopped (step

714

), and driven nudger rollers are stopped (step

716

). It is preferable that first output feeder

25

is decelerated at 1.0 g. If TE

16

were still in first output feeder

25

, rollers

27

,

29

would catch mailpiece

16

and stop it from advancing into aligner

31

. Sensor

211

is checked to see if a mailpiece is still in first output feeder

25

(step

720

). In

FIG. 9

f

, the answer is no, so trap

100

must be actuated (step

725

). Trap

100

is positioned in aligner

31

such that it will stop the shortest mailpiece at the last stopping position and, at the same time, will not pinch the longest mailpiece which is waiting at second singulator

39

. When the flag was set, second singulator feed assembly

50

remained running in order to clear the multi-feed. Once LE

13

passed sensor

241

, second singulator feed assembly

50

stops (step

735

), and second output feeder

41

strips mailpiece

13

from second singulator

39

.

In

FIG. 9

g

, the stop flag is still set, and mailpiece

13

is clear of sensor

241

, thus re-accelerating second singulator feed assembly

50

(step

737

) and mailpiece

15

. Because mailpiece

15

blocks sensor

231

, all upstream document handling subassemblies remain stopped (step

740

).

Once TE

15

clears sensor

231

, the trap can open (step

745

) and first output feeder

25

can start up again (step

747

), as shown in

FIG. 9

h

. First output feeder

25

is preferably accelerated at 1.0 g to achieve a desired velocity of 42 ips (˜107 cps). The stop flag is then cleared (step

750

) and the previous stop flag is set (step

755

). Although sensors

201

and

203

are clear (steps

520

&

540

), because the previous stop flag is set (step

560

), first singulator feed assembly

49

and the driven nudger rollers are not restarted until mailpiece

16

clears sensor

221

(step

570

).

FIG. 9

i

shows mailpieces

15

and

16

advancing. Because mailpiece

15

blocks sensor

241

, second singulator feed assembly

50

stops. Because mailpiece

16

has not yet passed sensor

221

, first singulator feed assembly

49

and the driven nudger rollers are still not yet restarted. Once TE

16

clears sensor

221

, as shown in

FIG. 9

j

, the previous stop flag is cleared (step

575

) and first singulator feed assembly

49

and the driven nudger rollers are reaccelerated (steps

565

&

567

).

The conditions and protocol for preferred operation of the document-handling subassemblies are summarized in TABLE 1.

Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific embodiments, details, and representative devices shown and described herein. Accordingly, various changes, substitutions, and alterations may be made to such embodiments without departing from the spirit or scope of the general inventive concept as defined by the appended claims. For example while the preferred embodiment is described in connection with a mail-handling machine, any apparatus for handling mixed or same sizes/thicknesses of documents or other articles can use the principles of the invention. Additionally, while singulators incorporating belts are described, it is known to use rollers in lieu of the belts. Furthermore, the retard assembly of second singulator

39

can also optionally be driven in two directions (backward and forward) to effectively process shearable documents. In addition, the preferable velocities and accelerations, as well as the preferable sensor placements, may be modified based on the dimensions, thicknesses, and weights of the documents being processed.

TABLE 1

Subassembly

Motion

Accel

Decel

Velocity

Start Trigger(s)

Stop Trigger(s)

Stack Advance

Accel/Vel/Decel

1.0 g

0.115 g

3.56 ips

Either or both sensor 251 or tilt

Sensor 251 and tilt sensor

sensor not tripped: stack advance

tripped: stack advance

runs

stops

Nudger Rollers

Accel/Vel/Decel

0.5 g

Stop

37.4 ips

Trailing edge at sensor 203 and

Stop flag set; Leading edge

sensor 201 unblocked if no piece

at sensor 203; Leading edge

previously “trapped”; triggered

at sensor 213 if sensor 201

when trailing edge passes sensor

is blocked

221 if piece previously “trapped”

Belt 18

Constant

—

—

TBD

—

—

First Singulator

Accel/Vel/Decel

0.5 g

Stop

42 ips

Triggered with nudger rollers or

Stop flag set; Leading edge

Feed

trailing edge at sensor 213 if no

at sensor 213 if sensor 201

piece previously “trapped”; if piece

or sensor 203 is blocked

previously “trapped,” trailing edge

passes sensor 221

First Singulator

Constant

—

—

4 ips

—

—

Retard

First Output

Accel/Vel/Decel

1.0 g

1.0 g

42 ips

Trailing edge passes sensor 231 if

Stop flag set

Feeder

stop flag set; otherwise running at

constant velocity

Transport belt

Constant

—

—

42 ips

—

—

Trap

On exception

—

—

—

Stop flag set and trailing edge is

Trailing edge passes sensor

passed sensor 211

231 if stop flag set

Second

Accel/Vel/Decel

2.0 g

Stop

35.4 ips

Trailing edge at sensor 241

Leading edge at sensor 241

Singulator Feed

Second

Constant

—

—

4 ips

—

—

Singulator

Retard

Second Output

Constant

—

—

35.4 ips

—

—

Feeder

Number	Name	Date	Kind
4451027	Alper	May 1984	A
5423527	Tranquilla	Jun 1995	A
5445369	Golicz et al.	Aug 1995	A
6135441	Belec et al.	Oct 2000	A

Apparatus and method for controlling a document-handling machine

Information

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Date Filed

Date Issued

Inventors

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Agents

CPC

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US

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Term Extension

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US Referenced Citations (4)