60/277,946 filed on March 22,2001 and serial no.

60/338,892 filed November 5,2001.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to an apparatus that is used for stacking sheets-like material, and more particularly, to an apparatus having particular use for stacking sheet- like material such as mailpieces e. g., envelopes, which apparatus can be used along with a postage meter (franking machine) in a mailing system for stacking the envelopes processed through the postage meter.

2. Description of Prior Developments Sheet stacking machines, such as mail stacking machines, have long been well known, and have been used quite successfully in conjunction with mailing machines or other mail processing or handling machines, such as mail sorting machines, stamp cancellation machines, mail

counting machines, inserting machines and envelope printing machines. Typically, these sheet stacking machines include an elongated frame which defines a feed path along which mail pieces are fed toward a stacking location, the feed path generally being disposed at a lower level than the mail piece output location of the mailing machine or other mail processing or handling machine, so that the ejected mail pieces fall upon an elongated conveyor belt mounted on the frame. This conveyor moves the mail pieces along a feed path to a stacking location, at the end of which there is an upwardly angled wall which forms a ramp against which the mail pieces are stacked by the conveyor belt. A relatively large pressure wheel is pivotally mounted over the conveyor belt at a point along the feed path which permits mail pieces ejected from a mailing machine or mail processing or handling machine to fall on the conveyor belt before passing under the pressure wheel, which rests on mail pieces with sufficient pressure to cause them to maintain effective feeding contact with the conveyor belt.

One problem with many known stacking machines is that they are generally incapable of producing a neat, even stack of mail pieces since the mailpieces do not fall on the conveyor belt in precisely aligned overlapping relationship, thereby resulting in a stack in which the mailpieces lie in slightly staggered relationship. This makes it difficult to handle a full size stack when it must be removed from the stacking machine.

Still another problem generally encountered with many stacking machines used with mail processing equipment is that they do not stack thick mail pieces as effectively

as they stack thin mail pieces because the greater stiffness of thick mail pieces makes it harder to urge these mail pieces under the pressure wheel and to push them up a ramp.

Thus, in the mail processing business and with regard to the technology of stacking sheet like material, there is a need for a reliable stacking apparatus that will insure a proper stacking of sheet materials, produce a neat and orderly stack of sheets, and not be materially affected by variations in the thickness of the sheets.

There is also a need for a reliable stacking apparatus in which the length of the capacity of the stacker has been increased while decreasing the conveyor belt length in a horizontal plane.

SUMMARY OF THE INVENTION The features and advantages of the present invention which overcame the disadvantages of prior art structures are achieved by an apparatus for stacking a stream of moving sheet-like material comprising: a first moving belt positioned at a first level, the first belt adapted to receive sheet material lying in a first orientation and position the sheets downstream of the first belt in an overlapped condition; a second moving belt positioned at a level lower than the first belt and positioned whereby the sheets travel from an end position of the first belt down a step to the second belt ; a first sensor positioned to sense break members in relation to the total thickness of the sheets on the first belt thereby causing an incremental movement of the first belt; a second sensor positioned in contiguous relation to the

step and adapted to sense the sheet-like material as the sheets drop down the step to a second orientation thereby incrementally moving the sheet-like material according to the increasing number of sheets on the second belt as they are stacked thereon in the second orientation; and a movable back stop member adapted to be secured to the second belt, and further adapted to help support and stack the sheets in the second orientation, the stop member moving with the movement of the second belt.

Another embodiment of the present invention relates to an apparatus for stacking a stream of moving mailpieces, the apparatus being adapted to be used in conjunction with a mailing system as the mailpieces are ejected seriatim from the mailing system. The stacking apparatus includes a first moving belt positioned at a first level, the first belt adapted to receive mailpieces lying in a first orientation and position the mailpieces downstream of the first belt ; a second moving belt positioned at a level lower than the first belt and positioned whereby the mail travels from an end position of the first belt down a step to the second belt; a first sensor positioned to sense break members in relation to the total thickness of the mailpieces on the first belt thereby causing an incremental movement of the first relation belt ; a second sensor positioned in contiguous relation to the step and adapted to sense the mailpieces as the mailpieces drop down the step to a second orientation thereby incrementally moving the mailpieces according to the increasing number of mailpieces on the second belt as the mailpieces are stacked thereon in the second orientation ; and a movable back stop member adapted to be secured to

the second belt and further adapted to help support and stack the mailpieces in the second orientation, the stop member moving with the movement of the second belt.

Still a further embodiment of the present invention relates to a method for stacking a stream of mailpieces within a mailing machine comprising the steps of positioning in a first orientation a plurality of mailpieces in an overlapped condition on a first moving belt ; positioning on a second moving belt in a second orientation a plurality of mailpieces from the first moving belt, the second belt being positioned at a lower level than the first belt; stacking the mailpieces in the second orientation on the second belt while supporting the stack of mailpieces on the second belt in the second orientation; and controlling the movement of the second belt in relation to the thickness of the stack of mailpieces on the second belt.

Still a further embodiment of the present invention relates to a modular mailing system including a module for stacking a stream of moving mailpieces. The stacking module includes the above-described features for a stacking apparatus as described hereinabove.

BRIEF DESCRIPTION OF THE DRAWINGS The foregoing aspects and other features of the present invention are explained in the following description, taken in connection with the accompanying drawings, wherein:

FIG. 1 is a side plan view of a stacking apparatus in accordance with the features of the present invention along with an apparatus which feeds sheet-like material to the stacker; FIG. 2 is a side plan view of a portion of the stacking apparatus in accordance with the features of the present invention particularly illustrating the overlapping feeding arrangement of the sheets-like material; FIG. 3 is a side plan view of a portion of the stacker apparatus in accordance with the features of the present invention particularly illustrating how the sheet's are supported by a support member on a second belt and how the orientation of the sheet members change from a first (primarily horizontal) orientation to a second (primarily vertical) orientation; and FIG. 4 is a side plan view of the entire stacker apparatus in accordance with the features of the invention illustrating the positioning of the various motors and sensors used in conjunction with the stacking apparatus.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT (s) The stacker apparatus in accordance with the features of the present invention can be used for stacking any type of sheets-like material, such as for example, sheets of paper, sheets of thin plastic etc. which are being fed through some sort of sheet conveying system. For purposes of being able to explain the details of the

present invention in the form of an example, this application shall describe a stacker apparatus that is used for stacking paper sheets in the form of mailpieces (e. g. envelopes) which are being fed within a mailing machine system. As shown in Fig. 1, the stacking apparatus 10 in accordance with the present invention is comprised of two different levels of belt-type conveyors, i. e. a first belt conveyor 11 called the"landing belt" and a second belt type conveyor 12 called the"stacking belt", the second belt or stacking belt being positioned lower than the first belt conveyor 11. As shown, the end portion 13 of the first belt conveyor is in contiguous relation and slightly overlaps the beginning portion 14 of the second or"landing"belt 12.

In accordance with the example that is being presented herein, mailpieces (e. g. envelopes) being fed within mailing system 15 are fed seriatim to first belt member 11 in a first orientation, or basically in a horizontal position. As illustrated in Fig. 2, envelopes 16 are fed seriatim from a mailing machine system 15 (see Fig. 1), and are positioned on belt 11 in an overlapped arrangement due to the interaction of break member 17 on the horizontally orientated envelopes.

The envelopes 16 are received on belt 11 from a mailing machine system 15. Mailing machine system 15 could be, for example, a modular mailing system, and the envelopes could be directly received on belt 11 from a mailing machine module where the envelope has been processed by a moistener and sealed, and is now ready to be stacked for further processing. The envelopes are received from mailing machine system 15 and placed in an overlap position on the first conveyor belt 11 (see Figs. 1 and

2). The mailing machine system 15 feeds the envelopes 16 out onto the belt conveyor machine 11 at a relatively fast pace in sequential, serial fashion, i. e. in seriatim so that the envelopes are oriented in a substantially horizontal position on belt 11. Mailing machine system 15 does not feed envelopes 16 in an overlapped condition but this occurs due to break member 17 and the speed of belt 11. The primary purpose of the first belt conveyor 11 and brake member 17 is to slow down the speed of the traveling envelopes 16 and place the envelopes in an overlapped arrangement, as clearly illustrated in Figs.

1-3. First belt conveyor 11 is positioned below the conveyor (not shown) within mailing machine system 15.

Brake member 17 is positioned over first conveyor belt 11 as clearly shown in Fig. 2. Brake member 17 is preferably formed of a plurality of stiff spring loaded finger members with a roller at the end laying on belt 11 (e. g. plastic fingers) that function to stop the movement of envelopes 16 and position the envelopes so that they lie in an overlapped arrangement on belt 11 as shown in Fig. 2. First conveyor belt 11 moves in an incremental fashion to accomplish the overlapped arrangement of the envelopes on belt 11. In operation, brake member 17 is first hit by the fast moving envelope 16 as it exits the mailing machine system 15 and the leading edge of each envelope drops down on conveyor belt 11 in a substantially horizontal position. A signal is sent from the mailing machine system 15 (e. g. from a feeder module in a modular mailing system) to the drive system for belt 11 as each envelope 16 is forwarded to belt 11. When the drive system for belt 11 receives such a signal it moves one increment ahead. This type of incremental movement by belt 11 produces the overlapped arrangement for a

series of envelopes 16. Brake member 17 is preferably made of stiff plastic fingers with a roller on their end laying on belt 11 and is formed of, for example, three stiff plastic finger elements in the same row. The end 18 of the brake member 17 have a roller to them as illustrated in Fig. 2. The bottom portion of break member 17 is laying on the first belt conveyor 11. The brake member 17 also includes a limit switch as specifically illustrated in Fig. 4. The function of the limit switch is to detect when the thickness of the envelope is very large. When this occurs the limit switch sends a signal to the first conveyor belt 11 to increase the speed of belt 11 and get the thick envelopes out of the brake area quickly. This is done to prevent the mailing machine system 15, which is in the process of continuously feeding envelopes 16 onto first conveyor 11, from being jammed up. The first conveyor belt 11 should always have the envelopes placed thereon in an overlapped fashion prior to the envelopes being transferred to the second belt 12. By employing a limit switch as described above, the balancing of the overlapped envelopes reverses a possible jam, and the mailing system is operated on an ad-hoc basis.

The brake member 17 can be switched to a 90-degree orientation assuming that the conveyor's orientation relative to the mailing machine system is switched 90 degrees. The screws that hold the brake in the frame must be undone and the brake physically attached at a 90- degree orientation.

There is a control mechanism for the overall control of the overlapped stack of envelopes being carried by the first conveyor 11 to a backstop support member 20 located

on and secured to the second conveyor belt 12 (see Fig.

3). As the stack of envelopes 16 against the backstop 20 gets thicker and smaller wheel 21 against the stack of envelopes (see Fig. 4) moves clockwise, and furthermore when the back stop 20 gets to a certain position, signals are conveyed to the second conveyor belt 12 to move incrementally. Fig. 4 also shows the location of various sensors and motor control sensors that are used in the system. The larger wheel 22 keeps track of very thick envelopes being carried by the first conveyor belt 11 and with its sensor can instruct the second conveyor belt 12 to move incrementally for the thicker envelopes.

It is preferable to have a drop off between the first and second conveyors 11 and 12. The reason for this is that if there is no such drop off, and the back plate 20 on the second conveyor belt 12 is at a steep angle, the envelopes 16 could fall over onto the second conveyor 12.

The bottom portion 16A of each of the envelopes 16 rest against the backstop 20 and slip down into the space 25 provided by the envelope drop point. The envelopes resting against back plate 20 on a second conveyor belt 12 are now in a substantially vertical position. A series of sensors 30,31 and 32 are positioned along the second conveyor belt 12 for the purpose of measuring the amount of capacity that is being used on conveyor belt 12 to support envelopes in a substantially vertical position. When, for example envelopes 16 have started to be dropped onto second conveyor 12, a trip sensor 33 which is built in above the step between belts 11 and 12, detects envelopes as they drop. Sensors 33 causes stepper motor 34 to turn on and incrementally move the stack of now vertically positioned envelopes 16 away from

the step area until the sensor is not longer triggered and the movement of belt 12 stops. Movement of belt 12 causes movement of back plate 20 since back plate 20 is secured to belt 12. There is approximately a 50 m. m step down distance from the first conveyor belt 11 to the second conveyor belt 12. The step (drop) from the first conveyor 11 to the second conveyor 12 can be as small as possible so long as the bottom portions 16A of envelope 16 keep together against back stop 20. As illustrated in Fig. 4, envelopes 16 enter the mail stream from a mailing system designated by arrow 29. The envelopes could be directly from a postage meter, a feeding device or an addressing system. The envelops are positioned substantially horizontally and move long until they turn towards a substantially vertical position and drop on to the second conveyor belt 12.

Conveyor belt 11 advances each time an envelope 16 arrives from the mail stream. The distance of a the advance depends upon the envelope length, (the envelope length information generally comes from a Feeder device) and the thickness of the arriving envelope.

Although back plate 20 is in a secure locked position onto conveyor belt 12, it has the option of being able to be moved by hand to reset the position of the back plate.

In the structure shown in Fig. 4 there is illustrated the use of three sensors along the second conveyor belt 12, i. e. a 0% sensor (indication that no envelopes are being supported on conveyor belt 12) ; a 75% full sensor (indicating that 75% of conveyor belt is being used, i. e. stacked with envelopes) ; and a 95% full sensor (indicating that 95% of conveyor belt 12 is being used i. e. stacked with envelopes).

When the back plate 20 reaches the 75% sensor 31, the postage meter positioned in the mailing machine will given an acoustic signal. On reaching the 95% full sensor 32, the entire postage meter stops working.

The 75% and 95% full sensors (31 and 32) are movable according to user needs. In addition, in accordance with the features of the present invention, the sensors employed in the system described herein can be optical, mechanical or electrical sensors.

It should be understood that the foregoing description is only illustrative of the invention. Various alternatives and modifications can be devised by those skilled in the art without departing from the invention. Accordingly, the present invention is intended to embrace all such alternatives, modifications and variances which fall within the scope of the appended claims.