CA2090255C

CA2090255C - Mailing machine including sheet feeding speed calibrating means

Info

Publication number: CA2090255C
Application number: CA 2090255
Authority: CA
Inventors: Alton B. Eckert, Jr.; Dennis M. Gallagher; Thomas M. Pfeifer; Richard P. Schoonmaker
Original assignee: Pitney Bowes Inc
Current assignee: Pitney Bowes Inc
Priority date: 1992-02-25
Filing date: 1993-02-24
Publication date: 1997-12-23
Anticipated expiration: 2013-02-24
Also published as: EP0562721A3; DE69309142T2; EP0562721A2; EP0562721B1; DE69309142D1; CA2090255A1

Abstract

A mailing machine base comprising, structure for feeding a sheet having a leading edge and a trailing edge in a path of travel, the sheet feeding structure including a roller, the sheet feeding structure including structure for driving the roller at a desired sheet feeding speed corresponding to a desired reference voltage, structure for controlling the sheet feeding structure, the controlling structure including a microprocessor connected to the roller driving structure, the controlling structure including structure for sequentially sensing the leading and trailing edges of the sheet in the path of travel and providing corresponding successive signals to the microprocessor, the sheet having a predetermined length from the leading edge to the trailing edge thereof: and the microprocessor programmed for providing a predetermined reference voltage corresponding to the desired sheet feeding speed, counting a time interval in response to receiving the successive leading and trailing edge signals, determining whether the counted time interval and the desired time interval are substantially equal, and storing the predetermined reference voltage as the desired reference voltage if the counted and desired time intervals are substantially equal.

The mailing machine base may also comprise a postage meter mounted on the base, the postage meter including a rotary postage indicia printing drum, the base including structure for driving the drum at a desired constant indicia printing speed corresponding to a desired reference voltage, the base including structure for controlling the postage printing drum, the controlling structure including a microprocessor connected to the drum driving structure, the controlling structure including structure for sequentially sensing a commencement and a completion of constant printing speed of the drum and providing corresponding successive signals to the microprocessor, the microprocessor programmed for providing a predetermined reference voltage corresponding to the desired drum printing speed, counting a time interval in response to receiving the successive constant speed commencement and completion signals, determining whether the counted time interval and the desired time interval are substantially equal, and storing the predetermined reference voltage as the desired reference voltage if the counted and desired time intervals are substantially equal.

Description

2 ~
C-674 -C;~n;l~

NU~ILING MAC~II~ IlIICWDIl~G S~E13T E~E:DING l~D PRI~:[NG
SPEED ~'AT~TP~ G NEANS

BACKGROUND OF THE lN V l1:N~l~lON

The present invention is g~erally concerned with apparatus i~cluding sheet fee~; n~ and printing structures, and more particularly with a mailing machine including a base adapted to have mounted ther~on a postage meter, and improved drive systems and control structures therefor.

This application is related to the following concurrently filed Canadian Patent Application by A. Eckert, Jr. et, al. and assigned to the assignee of the present invention: Serial No. (Applicants file C-692) for Mailing Machine Including Short Sheet Length and Skewed Sheet Detecting Means. In addition, this application is related to the following two C~n~d; an Patent Applications filed by A. Eckert, ~r., et. al. and also assigned to the assignee of the present invention: Serial No. filed December 8, lg~2 (Applicants file C-862) for Mailing Machina Including Shutter Bar Control System; and Serial No.
filed December 14, 1992 (Applicants ~ile C-863) for Mailing Machine Including Printing Drum Control System.

As shown in U.S. Patent No. 4,774,446, for a Microproces~or Controlled D.C. Motor For controlling Printing Means, issued September 27, 1988 to Salazar, et.
al. and assigned to the a~signee of the present invention, there is described a mailing machine which includes a base and a postage meter removably mounted thereon. The base includes sheet ~eeding structure for ~eeding a sheet in a downstream path of travel through the machine, and includes two sheet sen~ing structures located a known distance ~rom one another along the path of travel. And~ the postage meter includes a rotary printing drum for printing postage indicia on a sheet while fesding the sheet downstream in the 2~9~7;r}~
path of travel there~ene~th. The sensors successively sense the sheet in the path of travel and provide successive signal~ to a microprocessor to permit the time lapse between the signals to be used ~or calculating a count corresp~nA; n~
to the sheet fee~ speed. Moreover, the base includes a d.c. motor ~or driving the postage printing drum, and an en~o~r coupled to the drum drive sha~t for providing signals indicative of the position thereo~ to a counting circuit which, in turn, provides a count to the lo microprocessor indicative of the peripheral speed of the postage printing drum. And, the computer is programmed to successively sample the counts corresponding to the sheet feeding speed and the speed of the periphery of the drum to adjust the motor drive between sampling time instants and generate a motor drive signal for causing the motor to drive the drum at a velocity which matches the peripheral ~peed of the drum with the sheet fee~;n~ speed.

Thus it is know in the art to provide a closed loop, sampled data, feed back control system in a mailing machine base for continuously matching the peripheral speed of a postage printing drum to the feeding speed of a sheet.

As shown in U.S. Patent No. 4,864,505 ~or a Postage Meter Drive System, issued September 5, 1989 to Miller, et.
al. and assigned to the assignee of the present invention, there is described a mailing machine base haviny a postage meter mounted thereon, wherein the base includes a first d.c. motor for driving the postage printing drum via a drum gear in the meter~ a second d.c. motor for driving the structure for feeding a sheet through the ~çhîne~ and a third, stepper, motor for driving a linkage system connected in bearing engagement with the postage meter shutter bar for moving the shutter bar out o~ and into locking engagement with the drum drive gear.

Thus it is known in the art to provide three separate motors for driving the sheet feeding, shutter bar moving and postage printing drum driving structures in a mailing 2 ~ 9 ~ 2 ~ ~
machine base. And, it is known to provide a stepper motor ~or driving a linkage system to move tha postage meter shutter bar into and out o~ locking engagement with the drum drive gear.

As shown in U.S. Patent No. 4,7~7,311, ~or a Mailing Machine Envelope Transport Sy~tem, ~s~led Novem~er 29, 1988 to Hans C. Mol and assigned to the assig~e~ of the present invention. There is described a mailing machine base having a postage meter mounted thereon, wherein ~he time lapse between spaced sensors in the path of travel o~ a sheet is utilized by a microprocessor for calculating a sheet fee~
speed, and wherein the speed of a stepper motor, connected for driving the postage printing drum under the control of the microprocessor, is adjusted to match the peripheral speed of the drum with the sheet ~eeding speed.

Thus it i5: known in the art to provide a microprocessor driven stepper motor in a mailing machine base ~or driving a postage printing drum at a peripheral speed which matches the speed of a sheet fed therebeneath.

As noted abov~, the structures utilized in the prior art for sheet feeA;n~, shllttQr bar moving and postage printing drum driving purposes include the sophisticated feedback control system of the '446 patent, which continuously controls the motion of a postage printing drum to conform the same to a trapezoidal-.~hape~ velocity versus time profile, having a constant velocity portion which results in the peripheral speed of the drum matching the speed of sheets fed through a mailing machine, and include the relatively inexpensive alternative of the '311 patent, which includes a stepper motor operated for matching the peripheral speed of the drum to the sheet ~ee~ speed without regard to the acceleration and deceleration velocity versus ti~e profile characteristics of the drum. Each of such systems has its drawbacks, for example, encoder are expensive, as are software solutions which take into con~ideration the technical specifications of the motors .
, 2~3~ 3 controlled thereby. And both o~ suah expenses are major considerations in competitively pricing mailing ma~hines for the marketplace. Further, stepper motors are noisy, as are linkage systems, which tend to suffer from wear and tear over time and become noisy. Moreover, the combination of a stepper mokor and linkage ~y~tem for driving a shutter bar tends to cause the moving shutter bar to be ~oisy. In addition to being irritable to customers, noise normally signals wear and tear and, since mailing ~chln~s must normally withstand tha wear and tear of many thou~an~ of operational cycles in the course of their expected u6eful life, maintenance problems are compounded by the use of noisy systems in mailing machines. And7 such considerations are of major importance in generating and retaining a high level of customer satisfaction with the use of mailing mach;ne~. Accordingly:

an object of the invention is to provide an improved, low cost, low operational noise level, mailing machine base;

another object i~ to provide improved miolu~Locessor controlled sheet fee~;ng, shutter bar moving and postage printing drum dr~ving structures in a mailing machine base;

another object is to provide a microprocessor controlled d.c. motor for accelerating sheet feeding rollers at a substantially constant rate to a ~ubstantially constant sheet fee~ing speed;

another object is ~o provide a microprocessor controlled shutter bar moving system in a mailing machine base;

another object is to provide a microproc~ssor controlled d.c. motor for timely accelerating a postage meter drum from rest, in its home position, to a substantially constant velocity; and then maint~in~n~ the velocity constant;

2 ~ ~ ~ s~J ~ . j another o~ject is to pr~ide a microproce~sor controlled d.c. motor for timely co"Llolling deceleration of a postage printing drum ~rom a substantially constant velocity to rest in it~ home position;

another object is to provide a ~ethod and apparatus for calibrating the sheet fee~ speed of sheet feeding rollers to con~orm the speed to a predetermined speed;

another object is to provide a method and apparatus for calibrating the printing spesd of ~-rotary printing drum to conform the printing speed to the speed of a sheet ~ed thereto;

another object is to provide a method and apparatus for detecting skewed sheets fed to a mailing machine base; and another object is to provide a method and apparatus for detecting sheets of insufficient length ~ed to a mailing machine for printing postage indicia thereon.

SUMMARY OF THE lNv~NllON

A mailing machine base compri~ing, means for feeding a sheet having a leading edge and a trailing edge in a path of travel, the sheet fee~ing maans including a roller, the sheet feeding means including ~eans for driving the roller at a desired ~heet feedi ng speed corresponding to a desired reference voltage, means for controlling the sheet feeding means, the controlling means including a microprocessor connected to the roller driving means, the controlling means including mea~s for sequentially sensing the le~ and trailing edges of the sheet in the path of travel and providing corresponding successive signals to the microprocessor, the sheet having a predetermined length from the ls~in~ edge to the trailing edge thersof; and the microprocessor programmed for providing a predetermined reference voltage corresponding to the desired sheet fee~i nq 2~2-~ ~
speed, counting a time interval in response to receiving th~
successive leading and kraili~g edge signals, d~tel ;ning whether the counted time interval and the desired time interval are substankially equal, and storing the predetermined ref~rence voltage as the desired reference voltage if the counted and desired time intervals are ~ubstantially equal.

The mailing ~hine base also comprises a po tage meter mounted on the ba~e, the po~tag~ meter including a rotary postage indi¢ia printing drum, the base including means for driving the drum at a desired constant indicia printing speed corre~p~n~in~ to a desired reference voltage, the base including means for controlling the postage printing drum, the controlling means including a microprocessor connected to the drum driving means, the controlling means including means for sequentially sensing a c -nc- -nt and a completion of constant printing speed of the drum and providing corresponding successive signals to the microproces~or, the microprocessor programmed for providing a predetermined referenoe voltage corresponding to the desired drum printing speed, counting a time interval in response to receiving the successive constant spePd commencement and completion signals, deterr;n;ng whether the counted time interval and the desired time interval are substantially equal, and storing the predetermin~d reference voltage as the desired reference voltage if the counted and desired time intervals are substantially equal.

BRIEF DESCRIPTION OF THE DR~WINGS

As shown in the drawings wherein like reference numerals designate like or corresponding parts throughout th~ several views:

Fig. 1 is a schematic el~vation view of a mailing machine according to the invention, including a base having a postage meter mounted thereon, showing the sheet fee~in~
structure of the base and the postage printing drum of the 2 ~
meter, and showing a microprocessor for co~trolling the motion of th2 sheet feedilg structure and the drum;

Fig. 2 is a sah~matic end view o~ the mailing -chine of Fig. 1, showing ~he postage printing drum, ~rum drive gear and shutter bar of the meter, and showing the shutter bar and drum drive sy~tems o~ the base;

Fig. 3 is a 5Çh - - tiC view o~ ~tructure for sensing the angular position of the shutter bar cam shaft of ~ig. 2, and thus the location of the ~hutter bar relative to the drum drive gear;

Fig. 4 is a schematic view of structure for sensing the angular position of the printing drum idler shaft o~ Fig. 2, and thu~ the location o* the postage printing drum relative to its home position;

Fig. 5 is a s~he~tic view o~ the substantially trapezoidal-shaped velocity versus time profile of desired rotary motion of the postage printing drum of Fig. l;

Fig. 6 is a flow chart of the main line program o~ the microprocessor of the mailing machine base of Fig. 1, showi~g the 6upervisory process steps implementad in the course o~ controlling sheet fee~ing, and shutter bar and postage printing drum motion;
:
Fig. 7 is a flow chart of the sheet feeder routine of the microprocessor of Fig. 1, showing the process steps implemented for accelerating the sheet fe~di ng rollers to a constant f~e~ng spesd, and thereafter maint~ining the speed constant.
:
Fig. 8 i~ a *low chart of the shutter bar routine of the microprocessor of Fig. l, showing the process steps implemen ed for controlling shutter bar movement out o~ and into locking engag2ment with the postage printlng drum drive gear;

2 ~

Fig. 9 is a flow chart of the postage meter drum acceleration and co~stant velocity routine of the microprocessor of Fig. 1, showing the process steps implemented for controlling the rate of acceleration of the posta~e printing drum, ~rom rest in its home position to a substantially constant ~heet fee~n~ and printing speed, and therea~ter controlling the drum to maintain the speed constant;

Fig. 10 is a flow chart of the po~tage printing drum deceleration and coasting routine ~f t~e microprocessor of Fig. 1, showing the process steps implemented for controlling the rate of deceleration of the postage printing drum, from the substantially constant sheet ~eeding and printing speed, to rest in its home position;

Fig. 11 is a flow chart of the power-up routine of the microprocessor of Fig. 1, showing the process steps implemented for selectively causing the sheet fseding speed calibration routine(s) to be implemented;

Fig. 12 is a flow chart of the sheet feeder calibration routine of the microprocessor of Fig. 1, showing the process steps implemented for causing the sheet feeding speed of ~he sheet fee~i~g rollers to be conformed to a predetermined sheet f~e~i ng speed;

Fig. 13 is a flow chart of the rotary printing drum calibration routine of the microprocessor of Fig. 1, showing the process steps implemented for causing the printing speed of the postage printing drum to be conformed to a predetermined sheet fee~i ng speed;

Fig. 14 is a partial, schematic, top plan, view of the mailing machine of Fig. 1, showing successive positions of a sheet relative to the registration fence as the sheet is fad to the sheet sensing structure;

- ~ - 2 ~ e~ 3 Fig. 15 is a diagram showing a typical voltage versus time pxofile of the magnitude of the voltage of the signal provided to the microprocessor of FigO 1 by the sheet sensing structure of Fig. 14 a~ the ~heet i~ fed into blocking relationship with the sensing ~tructure;

Fig. 16 is a partial, schamatic, top plan, view of the mailing machine of Fig. 1, showing successive positions of a sheet which is typically skewed relative to the registration fence as the sheet is fed to the sheet sensing structure;

Fig. 17 is a diagram showing a typical voltage versus time profile of the signal provided to the microproce~sor of Fig. l by the sheet sensing structure of Fig. 16 as the typically skewed sheet is fed into blocking relationship with the sensing structure;

Fig. 18 is a flow chart of the sheet skew detection routine of the microprocessor of Fig. 1, showing the process steps impIemented for detecting successive unskewed, and typically skewed, sheets fed to the mailing machine base;

Fig. l9 is a partial, schematic, top plan view of the mailing machine of Fig. 1, showing successive positions of a sheet which is of insufficient length, are measured in the direction of the path of travel thereof, for example due to being atypically skewed relative to the registration fence, as the sheet is fed to the sheet sensing structure; and Fig. 20 is a diagram showing a typical voltage versus time profile of the signal provided to the microprocessor of Fig. 1 by the sheet sensing structure of Fig. l9 as a sheet of a predete r ; ne~ mini length, as measured in the direction of the path of travel, is fed to the sheet ~ensing structure~

DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown in FIG. 1, the apparatus in which the invention may be incorporated comprises a mailing machine 10 lo~ 2~

including a base 12 and a po~tage meter 14 which i~
removably mounted on the base 12.

The base 12 (Fig. l) generally includes suitable framework 16 for Aupporting the various component thereof including a housing 18, and a horizontally-exten~in~ deck 20 for supporting ~heetR 22 such a cut tapes 22A, letters, envelopes 22B, cards or other sheet-like materials, which are to be fed through the machine 10. Preferably, the base 12 also includes conventional stru~ture 24 for selectively deflecting an envelope flap 26 from an envelope body 28 together with suitable structure 30 for moistening the strip of glue 32 adhered to the envelope flap 26, preparatory to fee~ the envelope 22B through the machine 10. In addition, the base 12 pr2ferably includes an elongate angularly-exten~;ng deck 34 for receiving and guiding cut tapes 22A past the moistening skructure 30 preparatory to being fed through the machine 10. When mounted on the base 12, the postage meter 14 forms therewith a 36 slot through which the respective cut tapes 22A, envelopes 22B and other sheets 22 are fed in a downstream path of travel 3~ through the machine 10.

For ~eeding sheets 22 into the machine 10, the ba~e 12 preferably includes input ~ee~in~ structure 40 including opposed, upper and lower, drive rollers, 42 and 44, which are axially spaced parallel to one another and conventionally rotatably connected to the framework 16, as by means of shafts, 46 and 48, so as to extend into and across the path of travel 38, downstream from the cut tape receiving deck 34. In addition, the base 12 includes conventional intermediate fePd;n~ structure 50, including a postage meter input roller 52, known in the art as an impression roller, which is suitably rotatably connected to the framework 16, as by means of a shaft 54 so as to extend into and across the path of travel 38, downstream from the lower input drive roller 44. Still further, ~or feeding ~heets 22 from the machine 10, the ~ase 12 includes conventional output fee~ i ng structure 55, including an , 2 ~ ~ ~ 2 ~ ~

o~-~u~ feed roller 5~ which is suitably rotatably connected to the framework 16, as by means o~ a shaft 58, so a~ to extend into and acros~ the path o~ travel 38, downstream ~rom the impression roller 52.

As shown in Fig. 2, the postage meter 14 comprises ~ramework 60 for supporting the various components thereof including rotary printing structure 62. The rotary printing structure 62 includes a conve~tional postage printing drum 64 and a drive gear 6Ç there~or~ which are suitably spaced apart from one another and mounted on a common drum drive shaft 68 which is located above and axially extends parallel to the impression roller drive shaft 54, when the postage meter 14 is mounted on the base 12. The printing drum 64 is conventionally con~tructed and arranged ~or fseding the respective sheets 22 (Fig. 1) in the path of travel 38 beneath the drum 64, and for printing postage data, registration data or other selected indicia on the upwardly disposed surface of each sheet 22. When the postage meter 14 is mounted on the base 12, the printing drum 64 is located in a home position thereo~ which is defined by an imaginary vertical line L ext~;ng through the axis thereof, and the impression roller 5~ is located for urging each sheet 22 into printing engagement with the printing drum 64 and for cooperating therewith for fe~;ng sheets 22 through the machine 10. The drum drive gear 66 (Fig. 2) has a key slot : 70 formed therein, which is located vertically beneath the drum drive shaft 68 and is cent~red along an imaginary vertical line Ll which extends parallel to the home position line L of the printing drum 64. Thus, when the key slot 70 is centered ~eneath the axis of the drum drive shaft 68 the postage meter drum 64 and drive gear 66 are locat~d in their respective home positions. The postage meter 14 additionally includes a shutter bar 72, havin~ an elongate key portion 74 which is transversely dimensioned to fit into the drive gear's key slot 70. The shutter bar 72, which is conventionally slidably connected to the framework 60 within the meter 14, is reciprocally movable toward and away from the drum drivP gear 66, for moving the shutter bar's key - 12 - 2 ~ .i $

portion 74 into and out of the key ~lot 70, under the control of the mailing machines base 12, when th~ drum drive gear 66 is located in its home position. To that end, the shutter bar 72 has a ch~nnel 76 ~o~med therein from its lower surface 7~, and, the base 12 includes a movable lever arm 80, having an arcuately-sh~e~ upper end 82, which extends upwardly through an aperture 84 Pormed in the housing 18. When the meter 14 is mounted on the base 10, the lever arm's upper end 82 fits into the ch~nnPl 7~, in bearing engagement with the ~hutter bar 72, ~or reciprocally moving the bar 72> As thus aonstructed and arranged, the shutter bar 72 is movable to and between one position, wherein shutter bar's key portion 74 is located in the drum drive gear' key slot 70, for preventing rotation of the drum drive gear 66, and thus the drum 64, out of their respective home positions, and another position, wherein tha shutter bar's key portion 74 is located out of the key slot 70, for permitting rotation of the drum drive gear 66, and thus the drum 64.

The postaye meter 14 (Fig. l) additionally includes an output idler roller 90 which is suitably rotatably connected to the framework 60, as by means of an idler shaft 92 which axially extends above and parallel to the ou~put roller drive shaft 58, for locating the roller 90 above and in cooperative relationship with respect to the output feed roller 56, when the postage meter 14 is mounted on the base 12. Further, the base 12 additionally includes conventional sheet aligning structure including a registration fence ~5 de~ining a direction of the path of travel 38, i.eO, exten~ing parallel to the fence 95, and against which an edge 96 (Fig. 2) of a given sheet 22 is normally urged when ~ed to the mailing machine 10 for aligning the given shaet 22 with the direction of the path of travel 38. Moreover, the base 12 (Fig. 1) preferably includes sheet detection structure 37, including a suitable sensor 97A, located upstream from the input feed rollers, 42 and 44, for detecting the presence of a sheet 22 being fed to the machine 10. And, the base 12 preferably includes sheet 2~ 53 feeding trip structur~ 99, including a suitable sensor 99A, located downstream from th~ input feed roller , 42 and 44~
and preferably ~ubstantially one-half of an inch from, and thu~ closely alongside of, the regi8tration fence 94, for ~ensing the lea~ edge 100 and trailing edge lOOA o~ each sheet 22 fed thereby into the mailing machine 10.

A~ shown in Fig. 1, *or driving the input, inteL ~~i~te and o~L~uL sheet fee~n~ stru~u~s 40, 50 and 55, the mailing machine base 12 preferably includes a conYentional d.c. motor 110 having an output shaft 112, and a suitable timing belt and pulley drive train system 114 interconnecting the drive roller shafts 48, 54 and 58 to the motor shaft 112. In this connection, the drive train system 114 includes, for example, a timing pulley 116 fixedly secured to the motor output shaft 112 for rotation therewith and a suitable timing belt 118 which is looped about the pulley 116 and another timing pulley of the system 114 for transmitting motive power ~rom the pulley 116, via the remainder of the belt and pulley system 114, to the drive roller shaft~ 48, 54 and 58.

As shown in Fig. 1, for controlling the angular velocity of the sheet ~ee~;n~ rollers 44, 52 and 56, and thus the speed at which sheets 22 are fed into, through and from the machine 10, the mailing machine base 12 preferably includes a field ef~ect transistor (FET) power switch 120 which i~ conventionally electrically connected to the d.c.
motor 110 for energization and deenergization thereof. In addition, for controlling the sheet fee~;ng speed, the base 12 include~ the sheet detection structure 97 and sheet fee~in~ trip structure 99, a microprocessor 122 to which the FET power switch 120, sheet detection structure 97 and sheet fee~i ng structure 99 are conventionally electrically connected, and a voltage comparing circuit 124 which i~
conventionally electrically interconnected between the microprocessor 122 and d.c. motor 110. Preferably, the voltage comparing circuit 124 include~ a conventional solid state comparator 125, having the output terminal thereof - 14 - 2~

connected to the microprocessor 122. In addition, the comparator 125 has one of the ~nput terminals th2reof connected to the d.c. motor 110, ~or sampling the motor's back-e.m.f. voltage and providing a signal, such as the signal 126, to the comparator 125 which corresponds to the magnitude o~ the back-e.m.f. voltage. And, the comparator 125 ha the other of the input terminals thereof connPcted to the microprocessor 122 via a suitable digital to analog converter 128, ~or providing the comrArator 125 with a signal, ~uch as the signal 127, which corresponds to a predetermined referen~e voltage. Further, the base 12 inclu~es a conventional d.c. power supply 130, to which the FET power switch 120 and microprocessor 122 are suitably connected for receiving d.c. power. Moreover, the base 12 includes a manually operable on and off power switch 132, which is electrically connected to the d.c. supply 130 and is conventionally adapted to be connected to an external source of supply of a.c. power for energizing and dePnergizing the d.c. supply 130 in r~ponse to -nu~l operation of the power switch 132. In addition, ~or con~Lolling the sheet feeding speed, the microprocessor 122 is preferably programmed, as hereinafter discussed in greater detail, to respond to receiving a sheet detection signal, such as the signal 134, from the sensor 97A, to receiving a sheet feeding signal, such as the signal 135 from the sensor 99A, and to receiving successiYe positive or negative comparison signals, such as the signal 136 from the comparator 125, for causing the d.c. motor 110 to drive each of the sheet fee~ing rollers 44, 52 and 56 at the same peripheral speed for feeding sheets 22 through the machine 10 at a constant speed.

As shown in Fig. 2, for driving the shutter bar lever arm 80, the mailing machine base 12 preferably includes a conventional d.c. motor 140, having an output shaft 142, and includes a drive system 144 interconnecting the lever arm 80 to the motor shaft 142. The drive system 144 preferably includes a timing pulley 146 which is suitably fixedly connected to the output shaft 142 for rotation therewith.

15 ~ ~ " r~

In addition, the drive system 144 includes a cam sha~t ~48, which is conventionally journaled to the framework 16 for rotation in place, and includes a rotary cam 150, which is conventionally connected to the ca~ shaft 148 ~or rotation therewith. Moreover, the drive system 144 includes a timing pulley 152, which i~ suitably ~ixedly co~ected to the cam shaft 148 ~or rotation thereof. Preferably, the rotary cam 150 and pulley 152 are integrally ~ormed as a single piecepart which is injection molded from a suitable plastic material. In addition, the drive system 144 includes a conventional timing belt 154, which is suitably looped about the pulleys, 146 and 152, for transmitting rotary motion of the motor drive sha*t 142 to the cam shaft 148, and thus to the rotary cam 150. Still further, the drive system 144 includes the lever arm 80, which is pre~erably conventionally pivotally attached to the framework 16, as by means of a pin 156, and includes a yoke portion 158 depen~ing therefrom. Preferably, the rotary cam 150 is disposed in bearing engagement with the yoke portion 158 for pivoting the yoke portion 158, and thus the lever arm 80, both clockwise and counterclockwise about the pin 156.

For controlling movement of the shutter bar lever arm 80 tFig. 2), and thus :v.- ~t of the shutter bar 72, into and out of the drum drive gear slot 70, the mailing machine 12 includes the microprocessor 122, and includes the sheet feeding trip structure 99 (Fig. 1) which is conventionally electrically connectad to the microprocessor 122. In addition, for controlling shutter bar movement, the machine 10 (Fig. 2) includes a power switching module 160 which is connected between the d. c . motor 140 and microprocessor 122 .
Pre~erably, the switching module 160 includes four FET power switches arranged in an H-bridge circuit configuration for driving the d. c . motor 140 in either direction. In addition, the switching module 160 pre~erably includes conventional logic circuitry for interconnecting the FET
bridge circuit to the d . c . motor 14 0 via two electrical leads, rather than four, and ~or interconnecting the FE~
bridge circuit to the microprocessor 140 via two electrical leads, 161A and 161B, rather than four, such that one oP the leads, 161A or 161B, may be energized, and the other of the leads, 161B or 161A, deenergized, as the case may be, for driving the d.c. motor 140 in e~ther direction~ In addition, for controlling Vt ent of the shutt~r bar 72, the base 12 includes cam shaft sensing ~tructure 162 electrically connected the microprocessor 122. The structure 162 include~ a cam-shaped disk 164, which is conventionally fixedly mounted on the cam ~haft 148 for rotation therewith. The disk 164 (Fig. 3) includes an elongate arcuately-shaped lobe 166, having an arcuately-exten~; ng ~ i ?~ion dl which corresponds to a distance which is slightly less than, and thus substantially equal to, a predetermined linear distance d2 (Fig. 2) through which the shutter bar key portion 74 is preferably moved for moving the shutter bar 72 out of locking engagement with the drum drive gear 66. Preferably however, rather than provide the disk 164, the rotary cam 150 is provided with a lobe portion 166A which is integrally formed therewith when the ¢am 150 and pulley 152 are injection molded as a single piecepart. And, the shaft position sensing structure 162 includes conventional lobe sensing structure 168 having a sensor 170 ~Fig. 3) located in the path of travel of lobe, 166 or 166A as the case may be. As thus constructed and arranged, when the cam shaft 148 (Fig. 2) is rotated counter-clockwise, the lever arm 80 is pivoted thereby about the pin 156 to move the shl~tter bar 72 through the distance d~ and out of locking engagement with the drum drive gear 66. Concurrently, the lobe, 166 or 166A (Fig. 3), is rotated counter-clockwise through the distance d2, causiny the leading edge 172 thereof, followed by the trailing edge 174 thereof, to be successively detected by the sensor 170, for providing first and second successive transition signals, such as the signal 175 (Fig.
2~, to the microprocessor 122, initially indicating that movement of the shutter bar 72 has c_- ~nced and that the shutter bar 72 lobe 166 or 166A (Fig. 3) is blocking the sensor 170, followed by indi¢ating that movement of the shutter bar 72 (Fig. 2~ has been completed and that the - 17 ~

sensor 170 (Fig. 3) is unblocked. Th~rea~ter, when the cam shaft 148 (~ig. ~ i5 rotated clockwi~e, the lever arm 80 is pivoted thereby about the pin 156 to move the shutter bar 72 back through the distance d2 and into locki.ng engagement with the drum drive gear 66. And, concurrently, the lobe, 166 or 166A (Fig. 3), is rotated clockwise, through the distance d2 causing the trailing edge 174 ~hereo~, followed by the 1eA~ ing edge 172 thereof, to be successively detected by the sensor 170, for providing third and fourth succ~ssive transition signals 175 to the microprocessor 122 which again sllcce~sively indicate that movement of the shutter bar 72 has c~ ~nced and that the sensor 170 (Fig. 3) is blocked, and movement of the shutter bar 72 (Fig. 2) has been completed and ~he sensor 170 (Fig. 3) is unblocked. In additionr for controlling movement of the shutter bar 72 (Fig. 2), the microprocessor 122 is preferably programmed, as hereinafter described in greater detail, to respond to receiving a sheet fee~;ng signal 135 from the sensor 99A, and to receiving successive sets of transition signals 175 (Fig. 2) from the sensing structure 168, for timely causing the FET module 160 to drive the d.c. motor 140 to rotate the cam 150 counter-clockwise, for moving the shutter bar 72 through the distance d2 and thus out of lockiny engagemenk ~-ith the drum drive gear 66 and until the second of the successive transition signals 175 is received, and, after a predeter ; ne~ time interval during which the printing drum 64 is driven through a single revolution as hereina~ter discl~sQ~, for causing the FET module 160 to then drive the d.c. motor 140 to rotate the cam 150 clockwise, for moving the shutter bar 72 back through the distance d2 until the fourth of the successive transitions signals 175 is received to indicate that the shutter bar 72 has been moved into locking enga~ement with the drum drive gear 66.

As shown in Fig. 2, for driving the drum drive gear 66 and thus the drum 64, the mailing machine base 12 preferably includes a conventional d.c. motor 180, having an output shaft 182, and includes a drive system 184 for interconnecting the drum drive gear 66 to the motor shaft 182 when the postage meter 14 is mounted on the mailing machine base 12. The drive system 184 pre~erably includes a timing pulley 186 wAich is suitably fixedly connected to the motor output shaft 132 ~or rotation therawith. In addition, the drive system 184 includes an idler shaft 188, which is conventionally journaled to the fra~ework 16 for rotation in place, and includes a timing pulley 190, which is conventionally fixedly connected to the idler sha~t 18~ ~or rotation thereof. Moreover, the drive system 184 includes a conventional timing belt 192, which is suitably looped about the pullsys, 190 and 186, for tran~mitting rotary motion of the motor drive shaft 182 to the idler sha~t 188, and thus to tha pulley 190. Preferably, the base 12 additionally includes a pinion gear 194, which is conventionally mounted on, or integrally ~ormed with, the idler shaft 188 for rotation therewith. Further, the base 12 al~o includes an idler shaft 196, which is conventionally journaled to the framework 16 for rotation in place, and includes a drive system o~ t gear 198. Preferably, the output gear 198 is suitably ~; ~n~ioned relative to the drum drive gear 66 such that the gear ratio therebetween is one-to-one. And, the drive system ou~uL gear 198 is conventionally ~ixedly mounted on the idler shaft 196 for rotation thereof and is ~i n~ioned so as to extend upwardly through an aperture 199 formed in the housing 18 to permit the drum drive gear 66 to be disposed in e~hing engagement with the drive system output gear 198, when the postage meter 14 is mounted on the base 12, for driving thereby to rotate the printing drum 64 into and out of engagement with respective sheets 22 fed ~0 into the machine 10.

For controlling rotation of the drive system output gear 198 (Fig. 2) t and thus rotation o~ the printing drum 64, the mailing machine base 12 includes the microprocessor 122, and includes power switching structure 200 connected between the d.c. motor 130 and the microproc~ssor 122.
Preferably, the switching structure 200 includes a first FET
power switch 202, n ;n~lly called a run switch, which is energizeable for driving the motor 180 in one direction, n,~ ~

i.e., clockwise, and includes a seco~ FE~ power switch 204, nominally called a brake switch, connected in shunt with the first FET power switch 202, which is energizeable for dynamically braking the motor 1~0. In addition, for controlling rotation of the printing drum 64, the base 12 includes a voltage comparing circuit 206, which is conventionally electrically interconnected batween the microprocessor 122 and d.¢. motox 180. Preferably, the voltage omparing circuit 206 includes a solid state comparator 208, having the output t~rminal thereof connected to the micropro~e.ssor 122. In addition, the comparator 208 has one of the input terminals thereof connected to the d.c.
motor 180, Por sampling the motor's back-e.m.f. voltage and providing a signal, such as the signal 210 to the comparator 208 which corresponds to the magnitude o~ the back-e.m.f.
voltage. And, the comparator 208 has the other of the input teL ; n~l S thereof connected to the microprocessor 122, via a suitable digital to analog converter 212 for providing the comparator 208 with an analog signal, such as the signal 214, which corresponds to a predetermined reference voltage.
In addition, for controlling rotation o~ the printing drum 64, the base 12 includes idler shaft position sensing structure 220 electrically connected to the miaroprocessor 122. The structure 220 preferably includes a cam-shaped disk 222, which is conventionally fixedly mounted on the idler shaft 196 for rotation kherewith and thus in step with counter-clockwise rotation o~ the drum 64, due to the one-to-one gear ratio between the drive system output gear 19~ and drum drive gear 66. The disk 222 ~Fig. 4) includes two, elongate, arcuately-shaped lobes, 224 and 226. The lobes 224 and 226 are preferably separated from one another by a two degree gap 228 which is bisected by a vertical line L2 which extends through the axis of the disk 222 when the disk 222 is located in its home position, which home position corresponds to the home position of the drum drive gear slot 70 (Fig. 2) and thus to the home position of the printing drum 64. The lobe 224 (Fig. 4) has an arcuately-extending dimension d3, which corresponds to a distance which is preferably slightly less than, and thus ~ 20 -2 ~ 11 '. 3 substantially equal to, the lin~ar distance d4 (Fig. 1) through which the outer periphery of the printing drum 64 is ini~ially driven counter-clockwise from ths home position thereof before being rotated into engagement with a sheet 22 fed into th~ machine 10. And, the lobe 226 (Fig. 4) has an arcuately-ext~n~1ing ~ ~n~ion d5 which correspond~ to a distance which i8 preferably slightly 1~8 tha~, and thus substantially e~ual to, the linear di~tance d6 (Fig. 1) through which the outer periphery of the printing drum 64 is driven coun~er-clockwise upon being rotated out of engagement with a sheet 22 fed thereby through the machine 10. Further, the shaft position sensing structure 220 includes conventional lobe sensing structure 230 having a sensor 232 (Fig. 4) located in the path of travel of the lobes, 224 and 226. As thus constructed and arranged, assuming the shutter bar 72 (Fig. 2) is moved out of locking engagement with the drum drive gear 66, when the drive system output gear 198 commences driving the drum drive gear 66 and printing drum 64 from their respective home positions, the disk 222 (Fig. 4) is concurrently rotated counter clockwise from its home position. As the lobe 224 is rotated through the distance d3, causing the leading edge 234 of the lobe 224, followed by the trailing edge 236 thereof, to be successiv~ly detected by the sensor 232, succPssive first and second transition signals, such as the signal 240 (Pig. 2), are provided to the microproc~ssor 122, initially indicating that drum 64 (Fig. 2) has c~ ~-?nC~d.
rotation from the home position thereof, followed by indicating that the drum 64 has rotated 40~ through the distance d4. In addition, the transition siqnal 240 provided by the sensor 232 detecting the lobe's trailing edge 236 indicakes that the drum 64 has rotated into feeding engagement with a sheet 22 fed into the machine 10.
Thereafter, when the disk 222 and thus the drum 64 (Fig. 1~
continue to rotate counter-clockwise, and the printing drum 64 prints indicia on the sheet 22 as the sheet 22 is fed thereby through the machine 10, until such rotation causes the leading edge 242 ~Fig. 4) of the lobe 226, followed ~y the trailing edge 244 thereof, to be successively detPcted - 21 ~

by the sensor 232. Whereupon the sensor 232 provides successive thixd and fourth tran~ition signals 240 to the mi~,o~Locessor 122, initially indicating that the drum 24 has rotated 335~ and out of ~ee~in~ engagement with the sheet 22, followed by indicating that the drum 64 has rotated through 359~, and thus ~ubstantially through he distance d6 and back to the home position thereof. Still ~urther, for controlling rotation of the pr~nting drum S4, the microproce~sor 122 i preferably prO~L~ ~ 3d, a~
her~ina~ter described in greater detail, to timely respond to the completion of movement o~ the shutter bar 72 out of locking engagement with drum drive gaar 66, to timely respond to the transition signals 240 from the idler shaft sensing structure 230 and to timely respond to receiving s~cce~sive positive or negative comparison signals, such as the signal 248 from the comparator 208, to cause the FET
switch 202 to drive the d.c. motor 180 for initially accelerating the drum 64 through an angle of 40~, followed by driving the drum 64 at a constant velocity through an angle of 295~, to drive each of the rollers 44, 52 and 56 at the same peripheral, sheet feeAing, speed. Moreover, the microprocessor 122 is preferably progra~med to timely ~e~nergize the F~T run switch 202, and to energize the FET
brake switch 204 to thereafter decelerate and dynamically brake rotation of the motor 180 to return the drum 64 through an angle of 25~ to the home position thereof at the end of a single revolution of the drum 64.

In addition, for controlling operation of the base 12 (Fig. 1) and thus the machine 10, the base 12 prefarably includes a conventional keyboard 250 which is suitably electrically connected to the microprocessor 122 by means of a serial communications link 252, including a data input lead 254, for providing signals, such as the signal 255, to the microprocessor 122, a data o~L~u~ lead 256, for providing signals, ~uch as the signals 257 to the keyboard 250, and a clock lead 258 for providing clock signals to the keyboard 250 to synchronize co 1cakion between the keyboard 250 and microprocessor 122. The keyboard 250, - 22 - 2 ~ , t ~ ~

which has a plurality of -nllA~ly actuatable switching keys 260, preferably includes a print mode key 262, which is manually actuatable for causing the base 12 to enter into a sheet ~eeding and printing mode of operation, and a ~o-print mode key 264, which is -n~l~lly actuatable for causing the base 12 to enter into a sheet fee~i n~ but no printing mode of operation. Further, for providing a visual indication to an operator concerning a trouble condition in the machine 10, the keyboard 260 preferably include~ a service lamp 266 which is preferably intermittently energized in a light blinking mode of operation ~n response to ~ignals 257 ~rom the microprocessor 122 whenever the base 12 is in need of servicing, ~or example, due to the occurrenae of a j am condition event in the course of operation thereof.
Moreover, for controlling operation of the base 12, the base 12 preferably includes a manually actuatable test key 270, which is preferably dispos~d within the housing 18 of the base 12 for access and use by manufacturing and maint~nAnce personnel. The test key 210 is conventionally electrically connected to the microprocessor 122 and is ~ 1 ly actuatable to provide a signal, such as the signal 272, to the microprocessor 122 for causing the base 12 to enter into one or more calibration modes of operation, wherein the sheet fee~ing and prin~ing speeds of the base 12 and postage meter 14 are calibrated to ensure that the postage indicia printed on a given sheet 22 is acceptably located thereon.
Further, for storing critical data utilized for operation of the base 12 in various modes thereof, including the calibration mode(s), the base 12 preferably includes a suitable non-volatile memory (NVM~ 274 which is conventionally electrically connected to the microprocessor 122 and operable thereby for storing therein data without loss thereof due to power failure or during power-down conditions. And, to that end, the microprocessor 122 is preferably one of the type which includes an electrically erasibla, pro~r ~hle, read only, memory (EEPROM).

As shown in Fig. 6, in accordance with the invention the microprocessor 122 is preferably programmed to include a - 23 ~

main line program 300, which commence~ with the step 302 of conventionally initializing the microprocessor 122 (Figs. 1 and 2) in responRe to the operator -ml~lly moving the power switch 132 to the "on" position th~reof to e~ergize the d.c.
power supply 120 and thus the mailing machine ba~e 12. ~tep 302 generally includes e~tablishin~ the initial voltage levels at the microprocessor interface port~ which are utilized for ~n~in~ and receiving the signals 275, 272, 134, 176, 175, 240, 136 and 248 to and from the keyboard, tes~ key, ~ensor~ and compaxators ~50, 270, 97A, 99A, 170, 232, 125 and 248, (Fig. 1, 2, 3 and 4~ ~or controlling the various structures of the mailing machine base 12, and setting the interval timers and event counters of the microprocessor 122. Thereafter, the microprocessor 122 executes the step 304 (Fig. 6) of initializing the components of the aforesaid various structures. Step 304 generally entails causing the microproces~or 122 (Figs. 1, 3 and 4) to scan the microprocessor ports connected to the various sensors, 97A, 99A, 170 and 232, and, if necessary, to cause the main line program to enter into a print mode of operation and drive the motors 110, 140 and 180 for causing various components of the ~ase 12 and meter 14, including the drum drive gear 66, and thus the printing drum 64, to be driven to their respective home positions from which operation thereof, and thus of the mailing machine 10 may be initiated.

Assuminy completion of the initialization steps 302 and 304 (Fig. 6), then, according to the invention, the pLO~L
300 enters into an idle loop routine 306 which commences with the step 308 of detel in;n~ whether or nok a a machine error flag ha~ been set, due to the occurrence of various events, hereinafter discussed in greater detail, including, for example, the sheet fee~;ng structures 40, 50 or 55 (Fig.
1) being jammed in thè course of feedin~ a sheet 22 through the machine 10, the shutter bar 72 (Fig. 2) not being fully moved through the di~tance d2 in the course of movement thereof either out of or into locking engagement with the drive gear 66, or the meter drive system 184 being jammed in - 24 - 2q~ 2.

the course of driving ~he same. Assl i n~ a machine error flag has been set, step 308 (Fig. 6), the pLO~l - 300 LeL~ s processing to idle 306, until the condition causing the error flag to be set i8 cured and the error flag is cleared, and a determination is thereafter made that an error flag has not been set, step 308. Whereupon, the microprocessor 1~2 causes the program 300 to implement the step 310 of determining whether or not the sheet feeding or printing speed callbration flag has been set, due to the test key 270 (Fig. 1) having been actuated as hereinafter discus6ed. AS~I ~ng the calibration flag has not been set, step 310 (Fig. 6)~ the program 300 implements the step 312 of determining whether or not a shest detection signal 134 (Fig. 1) has been received from the sensor 97A of the sheet detection structure 97, and, as~l ; ng that it has not been received, step 312 (Fig. 6~, the program 300 loops to idle, step 306, and continuously successively implements steps 308, 310, 312, and 306 until the sheet detection signal 134 is received. Whereupon, the program 300 implements the step 314 of setting the sheet feeder routine flag "on", which results in the routine 300 calling up and implementing the sheet feeder routine 400 (Fig. 7), hereinafter discussed in detail.

As the routine 400 (Fig. 7) is being implemented, the program 300 (Fig. 6) concurrently implements the step 316 of determining whether or not the sheet detection signal 134 has ended, ~ollowed by the step 316A of setting the skew detection routine flag "on", which results in calling up and implementing the sheet skew detection routine 1000 (Fig. 6) hereinafter described in detail. As the skew detection routine 1000 is~being implemented, the program 300 (Fig. 6~
concurrently implements the step 317 of determining whether a skew flag ha~ been set, as hereinafter discussed in detail, indicating that thP sheet 22 (Fig. 1) being fed into the machine 10 is askew relative to the direction of the path of travel 38 defined by the registration fence 95.
Assuming, however as is the normal case that the kew flag is not set, step 317, then, the program 300 (Fig. 6) 2 ~ é~ ~

implements the step 318 of deteL ~ n; ng wh~ther the sheet fee~ing trip ~ignal flag has be2n ~et, indicating that a sheet feeding trip signal 135 (Fig. l) has been receivsd fro~ the sensor 99A o~ the sheet feeding trip structure 99.
Ass~ tha~ it is determined that the sheet detection signal 134 ha~ not ended, step 316 (Fig. 63 and, in additio~, it is determined that the sheet fee~in~ trip signal flag has not been set, tep 318 indicating that the microprocessor 122 has not received the sheet feeding trip signal, then, the program 400 returns processing to step 316 and continuously sl~ccPssively implements steps 316, 317 and 318 until the sheet ~eeding trip signal 135 is receivsd, step 318, before the sheet detection signal 134 is ended, step 316. I~, in the course of such processing, the sheet detection signal ends, step 316, before the sheet ~eeding trip signal is received, step 318, then, the program 300 implements the step 319, of setting the sheet feeder routine flag "off" followed by rekurning processing to step 312.
Thus the program 300 makes a determination as to whether or not both sensors 97A and 99A (Fig. 1~ are concurrently blocked by a sheet 22 fed to the machine 10 and, if they are not, causes sheet feeding to be ended. As a result, i~ an operator has fed a sheet 22 to the mailing machine base 12 and it is sensed by the sensor 97A, but is withdrawn before it is sensed by the sensor 99A, although the sheet feeding routine 400 (Fig. 7) has been called up and started, step 314 (Fig. 6), it will be turned off, step 319, until successive implementations of step 312 result in a determination that another sheet detection signal, step 312, has been received and the program 300 again implements the step 314 of setting the sheet feeder routine flag "on".
Assuming however, that both the sheet detection and feeding signals, 134 and 135, are received, steps 316 and 318, before the ~heet detection sign~l 134 is ended, step 316, then, the program 300 implements the ~tep 320 of deteL inin~
whether the base 12 is in the no~print mode of operation, as a result o~ the operator having actuated the no-print key 264 (Fig. 1). As~ iny that the no-print key 264 has been actuated, step 320 (Fig. 6), due to the operator having 26 2 ~ ~ ~ 2. . i ~

chosen to use the base 12 (Fig. 1) Por ~heet fee~in~
purposes and not for the purposs of op~rating the pos~ag~
meter 14, then, the program 300 (~i~. 6) by-passes the drum driving ~teps thereof and impl~ments the step 320A of causing program proce~sing to be delayed ~or a time interval sufficient to permit the sheet 12 being ~ed by the bas~ 12 to exit the machine 10. As~l ;n~ however, that the base 12 is not in the no-print mode o~ operation, step 320, then the program 300 implements the step 320B of determining whether the base 12 (Fig. 1) i~ in the print mode of operation, as a result of the operator having actuated the print key 262.
Assuming, the inquiry of step 320B (Fig. 6) is negative, due to the operator not having chosen to use the base 12 for both sheet fee~ing and postage printing purposes, then, the program 300 returns processing to step 320 and continuously successively implements steps 320 and 320B until the operator actuates either the print or no-print key, 262 or 264 (Fig. 1) to cause the inquiry of one or the other of steps 320 or 320B (Fig. 6) to be affirmatively determined.
2~ Assuming that the print key 262 is actuated, causing the inquiry of step 320B to be affirmative, then the program 300 implements the step 321 of starting a time interval counter ~or counting a predete~ in~ time interval td (Fig. 5~, of substantially 80 milliseconds, from the time instant that a sheek 22 (Fig. 1) is detected by the sensing structure 99 to the predetermined time instant that the printing drum 64 preferably commences acceleration from its home po~ition in order to rotate into engagement with the leading edge 100 o~
the sheet 22 as the sheet 22 is fed therebeneath.

Thereafter, the program 300 (Fig. 6) implements the step 322 of ~etting the shutter bar routine flag 7'on" r which results in the program 300 calling up and implementing the shu~ter bar routine 500 (Fig. 8), hereinafter discussed in detail, ~or driving the shutter bar 72 (Fig. 2) through the distance d~ and thus out of locking engagement with the drum drive gear 66. As the routine 500 (Fig. 8) is being implemented, the program 300 (Fig. 6~ concurrently implements the step 324 of detel ; ni ng whether or not the - 27 - 2~6.~

shutter bar 72 (Fig. 2~ has stopped in the course of ~eing driven through the distance d2 and thus out o~ lorki ng engagement with the drum drive gear 66. As~ that the shutter bar 72 i stopped, then, the prsgram 300 (Fig. 6) implements the step 326 of causing the shutter bar 72 (Fig.
2) to be driven back into locking engagement with the drum drive gear 66, step 326 (Fig. 6~, followed by ~e~ur-~ing processing to idle, step 306. If however, the shutter bar 72 (Fig. 2~ is not stopped in the course of being driven through the distance d2, and thus out of locking engagement with the dru~ drive gear 66, then, the program 300 (Fig. 6) implements the step 328 of dete~ ;ning whether or not the time interval count, started in step 321, has ended. And, assuming that it has not, the program 300 continuously loops through step 328 until the time interval td is ended.
Thereafter, before the program 300 implements the step 330 of setting the postage meter routine flag "on", which results in the program 300 calling up and implementing the postage meter acceleration and constant velocity, or postage printing, routine 600 (Fig. 9). The p~oy. 300 preferably implements the step 329 (hereinafter discussed in greater detail) of dete~ i ni n~ whether the sheet fee~ing trip signal flag found to be set in step 318 is still set, to determine whether the sheet 22 disposed in blocking relationship with the sensor 99A is still disposed in blocking relationship therewith after the time delay interval td of 80 milliseconds, and thus to determine whether the sheet 22 is o~ su~icient length for printing purposes. Assuming, at this ju~cture, as is the normal case that the ir,~uiry of step 329 is a~firmative, indicating that the sheet 22 is of sufficient length, then, the program 300 implements the step 330 of setting the postage met~r acceleration and constant velocity routine flag "on", which results in the program 300 calling up and implementing the postage meter acceleration and constant velocity, or postage printing, routine 600 (Fig. 9).

As the routine 600 (Fig. 9~ is being imple~ented, the ~oy~am 300 ~Fig. 6) concurrently implements the step 332 of clearing a time inte.rval counter for counting a ~irs~
predete~ ;~ed fault time interval, of preferably 100 millisecon~, during which the microprocessor 122 (Fig. 2~
preferably rsaei~e~ the initial transition signal 240 from the sensing struature 220, due to the printing lobe's le~;ng edge 234 (Fig. 4) being ~en~e~ by the sensor 232, indicating that the postage printing dxum 64 (Fig. 2) has commenced being drivan from its home position by the drum drive gear 66. Accordingly, after clearing the time interval counter, step 332 (Fig. 6), the program 300 implements the step 334 of detel ~n~n~ whether or not the printing drum ~4 has cr ~nce~ movement from its home position. And, assuming that it has not, the p~o~ 300 continuously successively implements the s~lccessive steps of dete~ ; n ~ ng whether or not the first fault time interval has ended, step 336, followed by deteL, ;n;ng whether or not the drum 64 has moved from its home position, step 334, until either the drum 64 has com ence~ moving before the first fault time interval ends, or the first fault time interval ends before the drum has commenced moving. Assuming the first fault time interval ends before the drum has moved, then, the program 300 implements the step 338 of setting a machine error ~lag and causing the keyboard service lamp 266 to c -nce bl;nk;nq, followed by the step 340 of causing a conventional shut-down routine to be implemented.
Accordingly, if the postage printing drum 64 is not timely driven from its home position at the end of the time delay interval td (Fig. 5) of substantially 80 millisecon~, and after c~mmencement of implementation of the postage meter acceleration and constant velocity routine, step 330 (Fig.
6), the program 300 causes processing to be shut down, and a blink;ng light 266 (Fig. 1) to be ener~ized to provide a visual indication to the operator that the mailing machine base 12 or postage meter 14, or both, are in need of servicing. At this ~uncture, the operator o~ the machine 1~
may ~ind, ~or example, that the drum 64 did not move from its home po~ition due to the postage meter 14 having insufficient funds to print the postage value entered therein by the operator for printing purposes, or some other - 29 ~

error condition has occurred in the meter 14 which preludes driving the drum 64 ~rom its h~me position. Alternatively, the operator may ~ind that a jam condition exists in the base 12 which prevent the dr~m drive ge~r 66 from driving the drum 64. Whatever may be the reason ~or the drum 6~ not being timely moved from its home po~ition during the time interval, the operator would normally cure the defect, or call an appropriate service person to do so, before the machine lO i6 returned to normal operation. Accordingly, as shown in Fig. 6, after implementation of the shut-down routine, step 340, the program 300 implements the step 342 of ~k; n~ a determination as to whether or not either o~ the print or no-print mode keys, 260 or 262, (Fig. l) is actuated. And, assuming that a mode key, 260 or 262, has not been actuated, which determination would normally indicate that the trouble condition which resulted in implementation of the shut down routine, step 340 (Fig. 6~
had not as yet been cured, then the program 300 causes processing to continuously loop through step 342 until one of mode keys, 260 or 262, is actuated. Whereupon the program 300 implements the step 344 of causing the error flag to be cleared, followed by returning processing to idle, st2p 306.

Referring back to step 33~ (Fig. 6), and assuming as is the normal case that the postage printing drum 64 is timely moved from its home position, i.e., before the first predeteL ; nq~ fault time interval is ended, step 336 (Fiy.
6), then, the pLOyl 300 causes the time interval counter to be cleared, step 346, and to c ~nce counting a second predetermined fault ~ime in~erval, of pre~erably lO0 milli~econds, during which the microprocessor 122 (Fig. 2~
preferably receives the next transition signal 240 ~rom the sensing structure 220, due to the printing lobe's trailing edge 236 (Fig. 4) being sens~d by the sensor 232, indicating that the postage printing drum 64 (Fig. 2) has rotated through the initial 40~ of rotation thereof from its ho~e position (Fig. 5). Accordingly, a~ter clearing the time interval count~r, step 346 (Fig~ 6), the program 300 - 30 - 2~

implements the ~tep 348 of det2.~ ining whether or not the 40~ transition signal 240 ha~ been received. And, assuming tha~ it has not, the program 300 continuously successively implements the successiYe steps of determining whether or not the second fault time interval has ended, step 350, followed by deteL inin~ whether or not the 40~ transition signal 240 has been received, step 348, until either the 40~
transition signal 240 is received before the second fault time interval ends, or the second ~ault time interval ends before the 40~ transition 3ignal Z40 i5 received. As~l ;ng that the second fault time interval ends before the 40~
transition signal 240 is received, then, the program 300 implements the step 352, corresponding to step 338, of setting a machine error flag and causing the keyboard service lamp 266 to commence blink;n~, followed by implementing the successive machine shut-down and start-up steps 340, 342 and 344, hereinbefore discus~ed in detail, and returning processing to idle, step 306.

On the other hand, as~l ;ng as is the normal ca~e that a determination is made in step 348 (Fîg. 6) that the 40~
transition signal was timely received, i.e., at the end of the time interval tl (Fig. 5) of preferably 40 milli~econds, and thus before the second predetermined fault time interval is ended, step 350 (Fig. 6), then, the program 300 cauces the time interval counter to be cleared and to c~ ?nce counting a third predetermined fault time interval, of preferably 50~ millisecon~, during which the microprocessor 122 (Fig. 2) prefera~ly receives the next transition signal 240 from the sensing structure 220, due to the printing lobe's leading edge 242 (Fig. 4) being sensed by sensor 232, indicating that the postage printing drum 64 (Fig. 2~ has rotated throug~ 335~ of rotation thereof from its home position. Thereafter, the program 300 implements the successive st~ps o~ clearing a second time interval counter, step 356, for counting the duration of actual constant speed of rotation of the postage printing drum 64~ followed by the step 358 of making a determination as to whether or not the 335~ transition signal 240 has been received, step 350.

31 ~ . ,'J ! ~

A~eumin~ that the 335~ transition signal 240 is not received, the program 300 ccntinuously successively implements the succe~sive steps o~ determining whether or not the third ~ault time interval has ended, step 360, 5 followed by determining whether or not the 335~ transition signal 240 has~been received, step 358, until either the 335~ transition signal 240 i~ received before the third fault time interval ends, or the third ~ault time interval ends be~ore the 335~ transition signal 240 is received.
10 As~ ~ng the third ~awlt time interval ends before the 335~
transition signal 240 is received, then, the program 300 implements the step 362, corresponding to step 338, of setting a machine error flag and causing the keyboard service lamp 266 to commence blinking, followed by 15 implementing the successive machines shut-down and start-up steps 340, 342 and 344, as hereinbefore discussed in detail and returning processing to idle, step 306~ However, assuming as is the normal case that a determination is made in step 358 that the 335~ transition signal 240 was timely 20 received, i.e., at the end of the time interval t2 (Fig. 5) of preferably 292 milliseco~, and thus before the third predete- ine~ ~ault time interval is ended, step 360, then, the program 300 implemen$s the step 363 of storing the actual time interval ~f duration of constant speed rotation 25 of the postage printing drum 64, followed by the step 364 of setting the postage met~r deceleration and coasting routine flag "on", which results in the program 300 calling up and implementing the postage meter deceleration and coasting ~ routine 700 (Fig. 10).

As the routine 700 (Fig. 10~ is being implemsnted, the program 300 (Fig. 6) concurrently implement~ the step 366 o~
clearing the time interval counter for counting a fourth predetermined fault time interval, o~ pre~erably 100 milliseconds, during which the microprocessor ~22 ~Fig. 2) 35 preferably receives the last trans~tion signal 240 from the sensing structure 220, due to the printing lobe's trailing edge 244 (Fig. 4) being sensed by the sensor 2 2, indicating that the postage printing drum 64 (Fig. 2) has rotated .

through 359~ of rotation thereof ~rom it~ home position and is thu~ one degree from returning thereto. Theraa~ter, the program 300 implements the step 368 o~ making a determination as to whether or not the 359~ transition ~ignal 240 has been received~ Assuming that it ha~ not, the program 300 continuously sllcce~ively implements the ~uccessive steps o~ determininy whether or not the fourth fault time interval has ended, step 370, followed by deteL i ni ng whether or not the 359~ transition signal 240 has been rece~ed, step 368, until either th~ 359~
transition signal 240 is received before the ~ourth fault time interval ends, or the fourth fault time int~rval end~
before the 359~ transition signal 240 is received. Assuming the fourth ~ault time interval ends before the 359~
transition signal 240 is received, then, tha program 300 implements the step 372, corresponding to step 33~, of setting a machine error flag and causing the keyboard service lamp 266 to commence blinking, followed by implementing the successive machine shut-down and start-up steps 340, 342 and 344, as herein~efore discussed in detail, and returning processing to idle, step 306. However, assuming as is the normal case that a determination is made in step 368 that the 359~ transition signal 240 was timely received, i.e~, substantially at the end o~ the time interval t3 of preferably 40 millisecon~, and thus be~ore the fourth predeteL ;ned fault time interval is ended, step 370, then, the program 300 implements the step 374 of determining whether or not the postage meter cycle ended ~lag has been set, i.e., whether or not the pos~age meter deceleration and coasting routins 700 (Fig. 10) has been fully implemented. As~ i ng that the postage meter cycle ended flag has not been set, step 374, then, the program 30Q
(Fig. 6~ continuously implements step 374 until the postage meter cycle ~nded flag has been set. Whereupon, the program 300 implements the step 378 of settin~ a postage meter trip cycle complete flag.

Thereafter, the program 300 ~ig. 6) implements the step 380 of setting the shutter bar routine flag "on", - 33 ~

which results in the program 300 calling up and implementing the shutter bar routine 500 (Fig~ 8~, as hereinafter discussed in d~tail, for driving the shutter bar 72 (Fig. 2) back through the distance d2 and into lo~k~ n~ engagement with the drum drive gear 66. As the routine 500 is being implemented, the pLO~ 300 concurrently implements the step 382 of detel in;ng whether or not the shutter bar 12 (Fig. 2) has stopped in the course of being driven through the distance d2 and thus into lo~ n~ engagement with the drum dri~e gear 66. Assuming the hutter bar 72 is ~topped, then, the program 300 (Fig. 6) implements the step 384 of setting the machine error ~lag and causing the keyboard service lamp 266 to commence blinking, followed by implementing the successive machine shut-down and start-up steps 340, 342 and 344, hereinbefore discussed in detail, and returning processing idle, step 306. If however, as is the normal case, a determinatiorl is made that the shutter bar 72 has not stopped, then, the program 300 implements the step 386 of deenergizing the FET brake switch 204 (Fig. 2~, to remove the shunt ~rom across the postage meter drive system's d.c. motor 180. Thereafter, the program 300 implements the step 320A of causing processing to be delayed for a predetermined time interval, of preferably 500 milliseconds, to permit the sheet 22 being processed by the machine 10 to exit the base 12, followed by the successive staps 390 and 392, hereinafter discussed in detail, of initially detel ining whether the stored, actual time intervals of acceleration and deceleration of the postage printing drum 64 (Fig. 2~, and the actual movement time interval o~ the shutter bar 72 in either direction, is not egual to the design criteria therefor, followed by incrementally changing the actual time intervals, as needed, to cause the same to respectively be equal to their design criteria value. Thereafter, the program 300 returns processing to idle, step 306.

As shown in Fig. 7, according to the invention, the sheet f~e~in~ routine 400 c. -nc~s with the step 401 of determining whether or not the sheet feader routine flag ~ 34 ~ 2 ~

setting is "o~~" due to an error ~vent occurring, such a~
one of the sheet feeder ja~ conditions hereinbefore discussed, in the cour~e of operation of the mailing ~achine base 12. Assuming that the ~heet feeder routine flag setting is "o~f~', step 401, the routine 400 continuously loops through step 401 unti~ the ~heet feeder routine llof~"
flag has been cl~ared, i.e., reset to "on", ~or example, due to the jam condition having been cured. However, assuming that the sheet feeder routine flag setting is "on" then, the routine 400 implements the step 402 of clearing a time interval timer and setting khe same for counting a first predetermined time interval, of preferably 30 millisecon~-c, during which the d.c. motor 110 (Fig. 1) is prefQrably energized for slowly accelerating the sheet feeding rollers, 44, 50 and 55, at a substantially constant rate during the predetermined time interval to a sheet feeding speed of twenty six inches per second for feeding one sheet 22 each 480 milliseconds. Thus the routine 400 (Fig. 7) cau~es the microprocessor 122 to implement the step 404 of energizing and d~energizing the FET power ~witch 120 ~Fig. 1) with a ~ixed, pulse-width-modulated, signal, such as the signal 405, which preferably includes 10 positive duty cycle energization pulses of one millisecond each in duration, separated by 10 deenergization time intervals of two milliseconds each in duration, so as to provide one energization pulse during each successive three millisecond time interval ~or 10 successive time intervals, or a total of 30 milliseconds. The energization pulses are .e~7cc~sively amplified by the ~T switch 120 (Fig. 1) and applied thereby t~ the d c~ motor 110 for driving the rollers 44, 52 and 56, ~ia the belt and pulley sy~tem 114.
Thereafter, the routine 400 (Fig. 7) implements the step 408 of deteL i n i ng whether or not the acceleration time interval has ended. Assuming the acceleration interval has not ended, step 408, the routine 400 loops to step 404 and successively implements steps 404 and 408 until the acceleration time interval is ended, step 408. In this connection it is noted that the preferred acceleration time interval of 30 milliseconds 1s not critical to timely accelerating the - 35 ~

s~eet feeding rollers 44, 52 and ~6 (Fi~ to the desired sheet feeding speed of 26 inches per sec~nd, since the time interval required for a given sheet 22 to be detected by the sensor s7A to ~he time instant it i~ fed to the nip of the S upper and lower input feed rollers, 42 and 44, is much greater than 30 milliseconds. A~ ; nr3 the time interval has ended, step 408, the routine 400 then implements the step 410 of initializing an event counter for counting a maximu~ predetermined number o~ times the counter will be permitted to be incremented, as hereina~ter discussed, befora it is concluded that a jam aondition exi ts in the sheet feeding structure. Thereafter, the routine 400 causes the microprocessor 122 to implement the step 412 of deter ;n;n~ whether or not the sheet feeder routine flag setting is lloff", due to an error event occurring, such as one of the jam conditions hereinbefore discussed, in the course of operation of the mailing machine base 12 As~l ; ng that the sheet feeder routine flag ~etting is "off", step 4~2, the routine 400 returns processing the step 401. Whereupon, the routine 400 continuously loops through step 401, as hereinbefore discussed, until the flag is reset to "on". Assuming, however that the sheet feeder routine flag setting is "on", for example due to the jam condition having been cleared, then, the routine 400 implements the step 414 of delaying routine processing for a predetermined time interval, such as two milliseconds, to allow Xor any transient back e.m.f. voltage discontinuities occurring incident to deenergization of the d.c. motor 110 to be damped. Thereafter, the routine 400 causes the microprocessor 122 (Fig. 1) to sample the ~u~p~L signal 136 from the comparator 125 to determine whether or not the d.c.
motor back e.m.f. voltage signal 126 is greater than the re~erence voltage signal 127, step 416 (Fig. 7).

Assume as in normal case that the back e.m.f. voltage is greater the re~erence voltage, step 416 (Fig. 7~, due to the rollers 44, 52 and 56 having been acaelerated to a shee~
~ee~;ng speed which is slightly greater than the desired sheet ~eeding speed of 26 inches per second, because the - 36 - ~ 2~j~3 rollers 44, 52 and 56 are no~ then under a loadO At thi3 juncture the sheet fee~;ng speed is substantially equal to the desired sheet feeding speed, and, in ord~r to maintain the desired sheet fee~ing speed, the routine 400 implemenks the successive steps o~ delaying processin~ one-hal~ a millisecond, followed by the step ~20 o~ clearing the ja~
counter, i.a., resetting the count to zero, and again implementing the step 416 o~ dete. ~ n~ n~ whether or not the motor back e.m.f. voltage is greater than the reference voltage. As~l in~ that the inquiry o~ step 416 re~;n~
affirmative, the routine 400 repeatedly implements steps 418, ~20 and 416 until the back e.m.f. voltage is not greater than the reference voltage, at which juncture it may be concluded that the sheet feeding speed of the rollers 42, 52 and 56 is no longer substantially at the desired sheet feeding speed. Accordingly, the routine 400 then implements the step 424 of incrementing the jam counter by a single count, followed by the step 426 of determining whether or not the number of times the jam counter has been in~L~--~nted is equal to a predeteL ;ne~ ~i count of, ~or example, 100 counts. And, assuming that the maximum count has not been reached, step 426, the microprocessor 122 causes the FE~ power switch 120 to be energized, step 428, for applying a d.c. voltage, such as the power supply voltage 134, to the motor 110, followed by delaying processing for a fixed time interval, step 430, of preferably two milliseconds, and then deenergizing the FET switch 431, step 431, whereby the FET
power switch 120 is energized for a predetermined time interval of preferably two milliseconds. Thereafter, processing is retuxned to step 414. Accordingly, each time the routine 400 sllccessively implements steps 414, 416, 424, 426, 428, 43~ and 431, the FET switch 120 and thus the d.c.
motor 110, is energized for a fixed time interv~l, steps 428, 430 and 431, and the jam counter is incremented, step 424, unless there i~ a determination made in step 416 that the d.c. motor back e.m.f. voltage is greater than the reference voltage, i.e., that the d.c. motor 110 is being driven substantially at the constant sheet feeding speed.

Referring back to step 416 (Fig. 7), and assuming that the comparison initially indicates that the ~ack e.m. f t iS
not greater than the reference voltage, indicating that the sheet fee~;ng rollers 44, 52 and 56 were not acaelerated substantially to the desired sheet feeding speed of 26 inches per second in the course o~ implementation o~ steps 402, 404, and 408, then, the routine 400 continuously successively implements step 424, 426, 428, 430, 431, 412, 414 and 416 until, as hereinbefore discussed the back e.m.f.
voltage ~cee~ the reference voltage, step 416, before the jam count -~ izes, step 426, or the jam count maximizes, step 426, before the back e.m.f. ~oltage s~cee~.~ the re~erence voltage.

Since each of such jam counts, step 426 tFig. 7), is due to a determination having been made that the d.c. motor back e.m.f. voltage is not greater than the reference voltage, step 416, it may be concluded that there is no d.c.
motor back e.m.~. voltage when the jam count reaches the ~; count, step 42~o That is, it may be concluded that the d.c~ motor 110 is stalled due to a sheet f~eAing jam condition occurring in the mailing -~h;ne 10. Accordingly, if the jam count has reached the m~i count, the routine 400 implements the successive steps of setting the sheet ~eeder ~lag "off", step 432, causing the keyboard service lamp 266 to cc -nce bl;~king, step 434, and then setting a : machine error ~lag for the main line program 300 ~Fig. 6).
Thereafter, t~e routine (Fig. 7) 400 le~uLI.s processing to step 401. Whereupon, assuming that the motor jam c~ndition is not cleared, the routine 400 will continuously loop through step 401 until the jam condition is cured and the "off" flag setting is cleared.

As shown in Fig. 8, according to the invention, the shutter bar routine 500 c~ ?nc~ with the step 502 of determining whether or not the shutter bar routine flag setting is "off", due to an error event occurring, such as the shutter bar 72 ~Fig. 2~ having been stopped in the couxse of being driven out o~ or into locking ~ngagement 2 ~
with the drive gear 66 i~ the cour~e of prior operation thereo~. Assuming that t~ ~hutter bar routine flag setting is "o~f", the routine 500 continuously 10DPS through step 502 until the shutter bar routine ~lag "o~f" setting has been cleared, i.e., reset to "ont', for example due to jam condition thereo~ having been cured. AS~I i ng as is the normal case that the shutter bar routine flag setting is "on" then, the routine ~0~ implements the step 503 o~
clearing a counter for counting the number of positive duty cycl~ energization pulses the microproc~Ror 122 (Fig. 2) thereafter applies to the FET power 8Wit~h in~ module 160 ~or drivinq the d.c. motor 140. Thereafter the routine 500 implements the successive steps 504 and 506 o~ energizing the appropriate lead, 161A or 161B, of FET power switch module 160 (Fig. 2), dep~n~;n~ upon the desired direction of rotation of the d.c. motor 140, with a first, fixed, pulse-vidth-modulated, signal, such as the signal 505, which preferably includes a single po~itiYe duty cycle energization pulse of from 500 to 800 microseconds in duration, step 504, followed by a single deenergization time interval of from 500 to 200 microseconds in duration, step 506, so as to provide one energization pulse during a one millisscond time interval. The signal 505, which is amplified by the FET switching modul2 160 and applied thereby to the d.c. motor 140, thus drives the motor 140 in the appropriate direction o~ rotation corresponding to the selected lead 161A or 161B, to cause the cam 150 to pivot the shutter bar lever arm 80 in the proper direction about the pivot pin 156 for causing the arm 80 to slidably move the shutter bar 70 partially through the distance d2 for movement thereof either out of or into locking engagement with the drum drive gear 66. Thereafter, the routine 500 (Fig. 8) implements th~ step 507 of incrementing the pulse count~r, cleared in step 503, a single count, followed by the step 508 of dete~ in;ng whether or not the shutter bar sensor 110 (Fig. 3) is blocked due to the shutter bar lobe's leading edge 172, or 174, being sensed thereby, indicatinq that the movement of the shutter bar 72 (Fig. 2) either out of or into locking engagement with the drum drive gear 66 2 ~ ~
has c~ enced, AS~ q the shutter bar sensor 170 (Fig. 3) is not blocked, then, the routine 500 (Fig. 8) implements the ~tep 510 of determining wheth~r or not a count of the - ~er of energizatis~ pul~e~ applied to the FET switch 140, step 504, has re~he~ a fir~t maximum count o~ preferably 35 pulses. As~uming the pul e count i8 less than the count, then, the routine 500 cau~es processing to be returned to step 504 and to continuously successively implement steps 504, 506, 507, 508 and 510, until either the shutter bar sensor 170 is blocked, step 508, be~ore the pulse count -~t izes, step 510, or $he pulse count -~; ;zes, step 51Q, before the shutter bar sensor 170 is blocked, step 508. As~ in7 the shutter bar sensor 170 is blocked, step 508, before the pulse count maximizes, step 510, then, the routine 500 implements the step 512 o~
setting a shutter bar sensor blocked flag and returning processing to step 510. Whereupon the routine 500 continuously successi~ely implements steps 510, 504, 506, 507, 508, and 512 until the pulse count -~i ;zes, step 510, followed by implementing the successive steps 514 and 516 of again energizing the appropriate lead, 161A or 161B, of FET
switching module 160, depending on the desired direction of rotation of the d.c. motor 140, with a #eCon~ fixed, pulse-width-modulated, signal 505, which preferably includes a single positiYe duty cycle energization pulse of from 250 to 400 microseconds in duration, step 514, and thus a duty cycle which is a predetermined percentage of, i.e., preferably 50~ ~f, the duty cycle of the fixst pulse-width-modulated signal 505, followed by a single deenergizati~n time interval of from 750 to 600 microseconds in duration, step 516, so as to provide one energization pulse during a one millisecond time interval. On the other hand, with reference to step 508, assuming the shutt~r bar sensor 170 is not blocked, be~ore the pulse count maximizes, step 510, then, the routine 500 directly implements the successive steps 514 and 516 without having set the shutter bar sensor ~locked flag in step 512~ Accordingly, whether or not the shutter bar sensor blocked ~lag is sat, step 512, the routine 500 implements the suc~csive steps 514 and 516 2 ~ ~P~
of energizing the F~T switahing module 160 with the second pulse-width-modulated signal 505 hereinbefore discussed.
Accordingly, during tha initial 15 millisecond time interval of energization of the FET ~witch, the sensor 170 may or may not have b0en blocked by the shutter bar 72, that is, the shutter bar 72 may ox may not have c~ -nce~ movement in either direction. And, in either eventuality the FET
switching module 160 i again energized to either initially move or continue to move the shutter bar 72. Thereafter, ~0 the routine 500 implements the step 517 of incrementing the pulse ~ounter, cleared in step 5~3, a single count, followed by the 518 dete~ i ni ~g whether or not the shutter bar sensor 170 is then or was previously blocked. Assuming the shutter bar sensor 170 is not blocked, then, the routine 500 implements the step 520 of determining whether or not the sensor 170 is unblocked and, in addition, whether or not the sensor blocXed flag is also set. Thus, the inquiry of step 520 is concerned with the occurrence of two events, that is, that the shutter bar sensor 170 (Fig. 3~ becomes blocked and, thereafter, becomes unblocked by the lobe, 166 or 166Ao As~- i n~ that the shut~er bar sensor 170 is not unblocked, whether or not the blocked sensor ~lag is set, or that the sensor 170 is unblocked but the blocked sensor flag is not set, then the routine 500 implements the step 522 of determlning whether or not the total count of the number of energization pulses applied to the FET switch 140, step 514, has reached a total maximum fault count of preferably 75 pulses. Assuming the total pulse count has not maximized, then, the routine 500 causes processing to be returned to step 514 and to continuously successively implement steps 514, 516, 517, 518, 5Z0 and 522 until the shutter bar sen~or is blocked and thereafter un~locked, step 520. Assuming as is the normal case that the shutter bar sensor is blocked, step 518, before the total pulse count has maximized, step 522, then, the routine 500 implements the step 523 of setting the sensor blocked flag before implementing step 520. If however, the ~hutter bar sensor is not therea~ter additionally unblocked, step 520, before the total pulse count has maximi~ed, step 522, the routine 500 concludes - 41 ~ Q'~ ~Ij 2 ~ 3 that either a fault in the po~tage meter 14 or a jam condition in the ba~e 12 is preYenting shutt~r bar movement.
Accordingly, the xoutine 500 implements the ~tep 524 of setting a shutter bar time out flay, ~ollowed by the step 526 of setting the shutter bar routine flag "off" and returning processing to step 502. Whereupon, processing will continuously loop through step 502 until the postage meter fault or jam condition is cured and the shutter bar routine flag is ~et "on". At this juncture it will be assu~ed, as is the no~mal case, that before the total pulse count has r~xi ; zed, step 522, the shutter bar sensor 170 is timely unblocked after having been blocked, step 520, i.e.
typically at the end of a desired predetermined time interval of preferably 30 milliseconds and thus typically when the pulse count is equal to 30. Thus the xoutine 500 answers khe inquiry of step 520, and implements the step 527 of storing the pulse count which, due to each count occurring during successive time intervals of one millisecond, corresponds to the actual time interval required to drive the shutter bar 72 (Fig. 2) through substantially the distance d2, without seating the same, and thus substantially either out of or into locking engagement with drum drive gear 66. Thereafter, in order to slow down movement of the shutter bar 7~ (Fig. 2), before the positively seating the same, the routine 500 preferably implements the step 528 (Fig. 8) of causing the microprocessor 122 (Fig. 2) to apply a two millisecond reverse energization pulse, to the FET switch lead 161A or 161~, as the case may ~e, which is opposite to the lead 161A
or 161B to which the enexgizati~n pulses of steps ~4 and 514, were applied. ~hereafter, the routine 500 implements the step 530 of delaying routine processing for a fixed time interval, of preferably twenty milliseconds, followed by the step 531 of clearing the pulse countex. ~hereupon, in order to positively seat the shutter bar while at the same time easing the shutter bar 72 to a stop to reduce the audible noise level thereof, the routine 500 implements the successive s~eps 532 and 534 of energi~ing the FET switching module 160 with a third ~ixed pulse width-modulated signal, - ~2 ~

of preferably a single positive duty cycle energizati~n pulse o~ 500 microseconds in duration, ~ollowed by a single deenergization time interval of 10 milliseconds in duration, step 534. Thereafter, the routine 500 impl~ments the step 535 of incrementing the pulse counter cleared in st~p 531 by a ~ingle count! followe~ by the step 536 of determining whether or not the nu~ber of energization pulses applied in step 532 is equal t~ a predet~ ;ne~ maximum count, o~
preferably four plllse~ A~suming that the pulse count has not maximized, then, the routine 500 returns proce~ing to step 532 and continuously 81~CC~BiV~ly implements steps 532, 534 ~nd 536 until the pulse count ~i ;zes step 536.
Whereupon the routine implements the step 526 of setting the shutter bar routine ~lag "off" and returning processing to step 502, which, as hereinbefore discussed, is continuously implemented by the routine 500 until the shutter bar routine flag setting is;'~on".

As shown .~n Fig. 9, according to the invention, the postage meter accelsration and constant velocity routine 600 com ?nçes with the step 602 of dete- ;ning whether or not the postage meter acceleration and constant velocity routine flag setting is "off", as is the normal case, until, in the course of execution of the main line program 300 (~ig. 6), : the program 300 implements the step 330 o~ setting the acceleration and constant velocity routine flag "on".
Assuming that the acceleration routine flag setting is "o~f", step 602 (Fig. 9), then, the routine 600 conkinuously implements step 602 until the "o~f" flag setting is cleared.
Whereupon, the routine 600 implements the step 603 of clearing and starting a time interval timer for measuring the actual time interval required to accelerate the postage printing drum 64 (Fig. 1) from its home position and into printing and ~eeding engagement with a sheet 22 ~ed therebenea~h. Thereafter, the routine 600 (Fig. 9) implements the successive steps 604 and 606 o~ energizing the FET run switch 202 ~Fig. 2~ with a fixed, pulse-width-modulated, signal, such as the signal 605, which preferably includes a single positive duty cycle -- 43 ~ ~ ; r~

energization pul~e of 1.5 mi~lt~c~n~ in duration, step 604, followed by a single deenergization time interval of 2 milliseconds in duration, step 606, so as to provide one energization pulse having a positive polarity duty cycle during a 3.5 mill;~scon~ time interval. Thereafter, the routine 600 implements the step 608 of causing the microprocessor 122 (Fig. 2) to sample the output signal 248 from the compara~or 208 to determine whether or not the d.c.
motor back e.m.f. voltag~ signal 210 is greater than the reference voltage si~nal Z14. I~ th~ comparakor signal 248 indicates that the back e.m.f. voltage is not greater than the reference voltage, step 608 (Fig. 3), it may ~e concluded that the p~stage printing drum 24 has not yet completed acceleration to the pred2te, ;ne~ constant velocity (Fig. 5), since the reference voltage corresponds to the predetel ined constant velocity that the drum 24 (Fig. 1) is preferably driven for fe~di n~ and pr~nting postage indicia on sheets 22 at a speed corr~sponding to the sheet f~e~in~ speed o~ the sheet feeding rollers 44, 52 and 56. Thus if the inquiry of step 608 (Fig. 9) is nega~ive, the routine 600 Le~r-ns processing to step 604, followed by continuously successively implementing steps 604, 606 and 608 until the d.c. motor back e.m.f~ voltage is greater than the re~erence voltage. Whereupon it may be concluded that the postage printing drum 6~ is being driven substantially at the predeteL ;ne~ constant velocity causing the periphery thereof to be driven at the desired sheet ~ee~ins and printing speed. Accordingly, the routine 600 then implements the successive steps of stopping the acceleration time ~terYal timer, step 60g, Pollowe~ by the 8t p 60~A of storing the actual time interval required for acceleration of the drum 64 (Fig. 1) to the constant velocity (Fig. 5).
Thereafter, in order to drive tha drum 64 to maintain the velocity constant, the routine 600 ~Fig. 9) preferably implements the successive steps 610 and 612 of energizing the FET run switch 202 with a second, pred~termined, pulse-width-modulated signal, which preferably includes a single positive duty cycle energization pulse of 4 milliseconds in durationl step 610, followed by a single 2 0 3 ~ hJ ~ ~
deenergization time interval of 2 milliseconds in duration, ~tep 612, so as to provide one energization pulse having a positive polarity duty cycle during a six millisecond time interval. Whereupon, the routine 600 implements the step 61~, correspon~in~ to ~tep 608, of deter~inin~ whether or not the d.c. motor back e~m.f. voitage is greater than the reference voltage, indicating that th~ postaga printing drum 64 is being driven faster than the predetermined constant velocity (Fig. 5) correspon~ing to the reference voltage, and thus faster than the sheet fee~ng speed of the rollers 44, 52 and 56 (Fig. 1). Assuming that the back e.m.f.
~oltage is greater than the reference voltage, step 614 (Fig. 9) the routine 600 continuou~ly successively implements the successive ~teps of dPlaying routine processing for 500 microsecon~, step 616, followed by ~ Lning processing to and implementing step 614, until the back e.m.f. voltage is not greater than the reference voltage. At which time it may be concluded that the d.c.
motor velocity ls less than, but substantially equal to, the constant veloc~ty corresponding to the re~erence voltag~, and thus less than, but substantially equal to, the sheet fee~ng speed of the sheet feeA;~g rollers ~4, ~2 and 56.
At this juncture, the routin0 600 implements the step 618 of detes ; n i ng whether or not the postzge meter acceleration and constant velocity routine ~lag setting is "off", indicating that the constant velocity time interval t2 (Fig.
5) has ended, so as to dete~mine whether or not the drum 64 should or should not be ~ecelerated to the home position.
If the ~lag setting is "on", in order to maintain constant velocity of the drum 64, the routine 600 (FigO 9) continuously successively implements the successiYe steps 610, 612, 614, 616 and 618 until the postage meter routine flag sstting is "of~". on the other hand, if the flag setting is "o~f", stap 61S, the routine 600 returns processing to step 602. Whereupon the drum 64 commences coasting and, as hereinbefore discussed, the routine 600 continuously implements step 602 until the postage meter acceleration routine flag is reset to "on".

- 45 ~

As shown in Fig. 10, according to the invention, the postage meter de~eleration and coasting routine 700 c~ -nc~ with th~ step 702 o~ d~ter ; n; n~ whether or not the deceleration and coasting routine flag setting is "off", a5 i8 the normal case, until, in the course of executi~n of the main line pr~ 300 (Fig. 6)~ the program 300 implement the step 364 of setting the deceleration and coasting routi~é flag "on". Accordingly, i~ the inquiry of step 702 (Fig. 10) is negative, the routine 700 continuously implements step 702 until the deceleration and coasting routine flag setting i9 "on". Whereupon the routine 700 implements the step 704 of setting the acceleration and constant velocity routine flag "o~f", which, as previously discussed, results the routine 600 (Fig. 9) returning processing to step 602. Thereafter, the routine 700 (Fig.
10) implements the successive steps of delaying routine processing for a time interval of preferably 100 microseconds, step 708, followed by the step 709 of clearing and starting ~a deceleration time interval timer for measuring the actual time interval required to decelerate the po~tage printing drum 64 (Fig. 1) out of feeding engagement with a sheet 22 being fed thereby and to return the drum 64 to its home position. Thereafter, in order to Cl -nce deceleration of the drum 64, the routine 700 initially implements the successive steps 710 and 712 of energizing the FET brake switch 204 (Fig. 2) with a first, fixed, pulse-width modulated signal, such as the signal 709, which preferably includ~s a single positive duty cycle energization pulse of 4 milliseconds in duration, step 710, followed by a single deenergization time interval of 2 millisecon~ in duration, step 712, so as to provide one energization pulse having a positive polarity duty cycle during a 6 millisecond time in~erval. Then, the routine 700 implements the step 713 of clearing a counter for counting the number of positive duty cycle energiz~tion pulses that the microprocessor 122 (Fig. 2) will thereafter apply to FET
brake switch 204 in order to continue decelerating rotation of the drum 64 to its home position. Thus the routine 700 (Fig. 10) thereafter implements the successive steps 714 and 2 ~
716 o~ energi~ing the FET brake switch 204 with a second fixed, pulse-width ~ ated signal 70~, which preferably includes a single positive duty cycle energization pulse o f one milliseconds in duration step 714, followed by a ~ingle deenergization ti~e interval of 2 ~illiseconds in duration step 716, so as to provide one energization pulse having a positive duty cycle polarity during a 3 milliseconfl time interval. Whereupon, the routine 700 implements the s~lccessiYe steps Q~ incrementing the pulse counter, cleared in step 713, a single count, followed by the step 718 of determining whether or not the pul~e count applied in step 714 is equal to a predetermined -~i count, of preferably 6 pulses. Assuming that the pulse count has not ~ ized step 718, then the routine 700 returns processing to step 714 and continuously successively implements steps 714, 716 and 718 until the pulse count -~i ;zes, step 718. At this juncture, rotation of the postage printing drum 24 will have been decelerated ~or a predetermined time ir.terval t4 (Fig.
5) of preferably substantially 24 milliseconds v~ the 40 milliseconds t3 preferably allotted for returning the drum 64 to its home position. Thus the drum 64 will have been decelerated sufficiently to permit the drum 24 (Fig. 1) substantially to coast to its home position. Accordingly, the routine 700 then implements the step 720 of reducing the value of the reference voltage signal 214 (Fig. 2) provided to the comparator 208 by the microprocessor 122, ~ollowed by the successive steps 720 and 722 of eneryizing the FET run swîtch 202 with a first, fixed, pulse-width modulated signal 605, which includes a single positive duty cycle energization pulse of prefexably 500 microseco~ in duration, step 720, followed by a single deen~rgization time interval of two milliseconds in duration, so as to provida one positive duty cycle energization pulse during a two and one-hal~ milli~econ~ ti~e interval. Whereupon the routine 700 implements the ~tep 724 of cc -ncing deterr;nin~
whether or not the microprocessor 122 (Fig. 23 has received the last transition signal 240, due to th~ trailing edge 244 (Fig. 4) o~ the printing lobe ~26 being detected by the sensor 232, indicating that the postage printing drum 64 ~ 47 (Fig. 1) has returned to its home position, step 724.
AS~ ; ng the drum home position signal 240 has not been received, step 724, then, the routin~ 790 implements the step 726 of causing the microproces~or 122 (Fig. 23 to sample the comparator output signal 248 to determina whether or not the d.c. motor ~ack e.m.f. ~ignal alo i~ greater than the re~llced reference voltage signal 214. Thus, although the drum ~4 will have initially been driven to its home position since the reference voltage has been re~-~ce~, the comparator 208 will at l~ast initially indicate that the d.c. motor ~ack e.m.f. ~oltage is greater than the reduced reference voltage, step 726, (Fig. lO) indicating that the d.c. motor is rotating too fast with the result that the routine 700 will continuously successively implement the successive steps of delayiing routine processing for 500 microseconds, step 728, allowing the drum to coast to the home position, followed by again implementing step 726, until the back e.m.f., voltage is no longer greater than the reduced reference voltage. At this juncture it is noted that although the drum home position signal 240 (Fig. 2) has not be~n received, since the d.c. motor back e.m.~. is less than the reference voltage it may be concluded that the drum 64 has coasted substantially to the home position. Thu~, the routine 700 ~Fig. 10) then implements the successive steps o~ stopping the deceleration time interval timer, step 729, set in step 709 followed by storing the actual deceleration time interval, step 729A. Whereupon the microprocessor 122 drives the drum 64 to its home position by returning processing to step 720 and succ~ssively implementing steps 720, 722 and 724, with the result that the dru~ home position signal 240 is received, step 724. Thus~ due to utilizing a reduced reference voltage, when comparing the same to the motor back e.m.f. voltage, the drum 64 is permitted to coast under the control of the micr~processor 122 until just prior to returning to its home position, at which juncture the drum is driven to its home position under the control of the microprocessor 122. Thereafter, the routine 700 implements the step 730 of energi~ing the FET
brake switch 204 with a single po~itive polarity duty cycle 2 ~ n ~
pulse of thirty milli.~econ~.~ in duration, to positively stop rotation o~ the drum 64 (Fig. 2l at the home position.
Whereupon the routine 700 (Fig. ~0) implements the successive steps o~ setting a postag~ meter cycle end flag for the main line program, ~tep 732, followed by causing the deceleration and coasting routine flag to be sek to lloff", step 734, and then returning proce~sing to step 702, which, as hereinbe~ore ~i~c~ e~, is continuously implemented until the postage meter routine d~ccleratiDn and coasting routine flag setting is 'lon".

As hereinbe~ore noted, in the course of implementation of the shutter bar routine 500 (Fig. 8), and, in particular, in the course of implementation of step 527, the actual time interval required to drive the shutter bar 72 (Fig. 2) in either direction through the distance d2 is stored during each sequence of operation of the routine 500 (Fig. 8).
Correspondingly, in the course of implementation of the postage meter acceleration and constant velocity routine 600 (Fig. 9) and, in particular in step 609A thereof, the actual time interval required to accelerate the postage printing drum 64, from rest to the desired sheet ~eeding and printing speed of 26 ;~oh~s per second, is stored during each sequence o~ operation of the routine 600 ~Fig. 9). And~ in the course implementation of the postage meter deceleration and coasting routine 700 (Fig 10), and, in particular, in step 729A thereof, the actual time interval required to decelerate the postage printing drum 64, from the constant sheet fee~;ng speed thereof to substantially at rest at the home position thereof, is stored during each sequence of operation of the routine 700 (Fig. 10). Moreover, as hereinbefore discussed, each sequence of operation of the shutter bar, acceleration and deceleration routines 500 (Fig. 8), 600 (Fig. 9) and 700 (Fig. 10~, is under the control of the mai~ lina program 300 (Fig. 6), which preferably includes the step 3~0, implementad in the course o~ each sheet 22 ~eing fsd through the machine 10, of making successive or parallel determinations as to whether the stored actual value of the time interval for driving the - 4g -2 ~ i 5 shutter bax in either direction is not equal to the preferred time interval o~ 30 ~illisecon~, whether the stored actual values of the time interval ~or acceleratin~
the postage meter drum is not equal to the preferred time interval of 40 milli~econ~-q, and whether the stored actual value of time i~terval for deceleration o~ postage meter drum is not equal to 40 milliseco~/ step 3909 As~l ;ng the inquiry of step 390 is negatiYe, the routine 300 returns processing it idle, ~tep 306. A~suming however, that the 19 inquiry of step 390 i~ affirmative, with respect to one or more of the deter~inations, then, the routine 300 implements the step 392 of selectively changing the duty cycle of the energization pulses provided to the H-bridge FET module 160 (Fig. 2) or ~ET run switch 202, or both, during each sequence o~ operation thereof, by predetermined incremental per¢entages or amounts tending to cause the shutter bar drive motor 140 or postage meter drum drive motor 180, or both, to timely drive the shutter bar 72 or timely accelerate or decelerate the drum 64, as the case may be, in accordance with the preferred, design criteria, time intervals noted above.

As shown in Fig. 11, according to the invention the microprocessor 122 is preferably additionally programmed to include a power-up routine 800 which is called up in response to the operator manually moving the power switch 132 (Fig. 1) to the "on" position thereof to energize the d.c. power supply 122 and thus the mailing machine base 12.
The routine 800 preferably c_ ~nces with the step 802 of determining whether or not the test key 270 (Fig~. 1) has been manually actuated, for example at the time o~
completion manufacture of the mailing machine base 1~ or thereafter in the course of the operational li~e of the base 12, preferably by a qualified manufacturer's representative having access to the test key 270. Assuming that the test key 270 (Fig. 1) is not actuated, step 802 (Fig. 11), the power-up routine 800 implements the step 804 of calling up and commencing implementation of the main line program 300 ~Fig. 6). Whereupon, the ~ain line program 300 is implemented as hereinbefore discussed. On the other hand, assuming the test key 270 (Pig. 1) is actuated, then before implementing the step 804 of calling up and imple~enting the main line ~Loy~m 300 (Fig. 6), the routine 800 (Fig~ 11) preferably initially implements the step 806 of calling up and implementing the sheet feeder calibration routine 850 (Fig. 12) followed by the step 808 of calling up and implementiny the print drum cali~ration routine (Fig. 13~.
Alternati~ely, when the test key 270 (Fig. 1) is actuated, step 802 (Fig. 11~ the routine 800 ~ay only call up and implement the print drum calibration routine, step 808.

As shown in Fig. 12, the sheet feeder~ or fee~ing speed, calibration routine 850 commences with the step 852 of causing the microprocessor 122 (Fig. 1) to provide a re~erence voltage signal 127 (Fig. 1) predete. ine~ by suitable data stored in the non-volatile memory (NVM) 274 of the mi¢roprocessor 122, and fetched therefrom for use by the routine ~50, to correspond to the desired sheet feeding speed, of twenty-six inches per second, of the sheet feeding rollers 44, 52 and 56. Thereafter the routine 850 implements the step 854 o~ setting the sheet ~eeder routine flag "on", which results in the routine 850 calling up and implementing the sheet feeder routine 400 (Fig. 7~. As the sheet ~eeder routine 400 is being implemented, the routine 850 (Fig. 12) concurrently implements the step 856 of deter ;ning whether or not the sheet feeder sensing structure 99A (Fig. 1) has detected a sheet 22 fed to the mailing machine base 12, and, asY~ in~ that it has not, the routine 850 ~Fig. 12) continuously loops through step 856. At this juncture, the operator preferably feeds one of the elongate cut tapes 22A, having a longitudinally-ext~n~ length of preferably six ; nche~, to the mailing machine base 12, as a result of which the inquiry of step 856 (Fig. 12) becomes affirmativ0, and, the routine 850 implements the step 858 of clearing and starting a timer for counting a time interval ~r~m the time instant the sensor 99A (Fig. 1) detects the leading edge 100 of the cut tape 22A to the time instant that the sensor 99A

~ 51 ~ s~ r~

detects the trailing edge lOOA of the cut tape 22A.
~ccordingly, subsequent to starting the timer, step 858 (Fig. 12) the routine ~50 implements the step 8S0 of determining whether or not the sen60r 99~ (Fig. l) becomes unblocked after havi~g been blocked. That is, whether the sensor 99A has detected the trailing edge lOOA o~ the cut tape 22A. Asx~ ; n7 the sen~or 99A has not detected the cut tape trailing edge lOOA, step ~60 (Fig. 12), the routine 850 continuously suc~es~ively implements step 860 until the 1~ sensor 99A is u~blocked after haYing been bloaked.
Whereupon, the routine 850 implements the step 862 of stopping the time interval timer, followed by the s~ep 864 of dete r ; n; ng whether the actual, measured, tlme interval for ~ ;nq the six inch cut tape 22A (Fig. 1) is equal to the desired time interval ~or feeding a sheet, i.e., at a constant speed of 26 inches per second. Ass~ i n~ the measured and desired time intervals are equal, step 864 (Fig. 12), the routine 850 implements the step 868 of storing the predete- ine~ reference voltage of step 852, as the desired reference voltage for subsequent use by the microprocess~r 122 (Fig. l) for, as hereinbefore discussed, causing sheets 22 to be fed at the desired constant sheet fee~n~ speed of 26 ;nche~ per second. Thereafter, the routine 850 implements the step 870 of setting the sheet fee~in~ routine flag ~loff'l, followed by the step 872 of returning processing to step 808 (Fig. ll) of the power-up routine 800, for implementation of postage meter, or printing speed, calibration routine 900 (Fig. 13). on the ~ther hand, as~l i n~ the actual and desired time intervals are not equal, step 864 (Fig. 12), then, the routine 850 implements the step 874 of calculating a new predete.~ined reference voltage, which is either greater or less than the initial predetermined reference voltage of ~tep 852, depsnding upon ~hether the actual time interval was less than or greater than the desired time interval, step 864, and returns processing to step 85S. Whereupon the routine 850 again successively implements steps 856, 858, 860, 862 and 864 and thus makes a second determination, step 864, as to whether the measured and desired time intervals are - 52 ~ s equal. Assuming at this juncture that the inquiry o~ step 864 is a~firmative, the routine 850 then implements the successive steps 868, ~70, and 872 o~ storing in the ~VM 274 (Fig. 1) thQ calculated reference voltage, step 866 (Fig.
12), ~hich xesulted in the ~ red and de~ired time intervals being found to b2 e~ual ln step 864, as the new desired, predetermined, reference voltage for subsequent use by the sheet fee~ing routine 400 (Fig. 7). Assuming however, that the inquiry of step 866 continues to be negative, the routine 850 continuously implements the sllccP.ssive steps 856, 858, 860, 862, 864 and 874 until the measured and desired time intervals are equal, followed by the step 868 of storing the latest calculated raference as the new desired reference voltage for use by the sheet feeding routine 400 ~Fig. 7) ~e~ore implementing the successive step 870 and 872 (Fig. 12) of sett.ing the sheet feeder routine flag "off" and returning processing to the power-up routina 800 as hereinbefore discussed.

As shown in Fig. 13, the postage meter, or printing speed, calibration routine 900 preferably commences with the : step 902 of dete~ ;n;n~ whether or not the print key 262 (Fig. 2) is actuated, and, assuming that it is not actuated, continuously successively impl~ments step 902 (FigO 13~
until it is actuated. Whereupon, the routine 900 implements the step 904 of causing the microprocessor 122 (Fig. 2J to provide a reference voltage signal 214 (Fig. 2), predete~ ;ne~ by suitable data stored in the NVM 274 (Fig.
1) of the microprocessor 122 and ~etched therefrom for use by the routine 900, corresponding to the desired constant velo~ity (Fig. 5) at whiGh the postage printing drum 64 (Fig. 2) is to be driven such that the peripheral feeding, or printing, speed thereof corresponds to the preferred sheet feeding speed of 26 inches per second. Thereafter, the routine 900 implements step 905 of causing the main line 3~ pro~ram 300 (Fig. 6) to be implamented, followed by the step 906 (Fig. 13) of setting the calibration flag.

- 53 - ~

~s shown in Fig. 6, when the calibration ~lag is set, step 310, the main line psOyL 300 bypasses step 312, 314, 316, 317, 318, 320 and 32~B, which are concerned with operation of the sheet ~ee~;n~ ~tructure (Fig. 1), in response to a sheet 22 being detected by both o~ the sensing structures 97A and 99A, as here~nbe~ore discusse~ in detail.
Thus, if the calibration flag is ~et, step 310, the routine 300 does not imple~nt the step 314 o~ setting the sheet feeder routine flag "on", as a result of which the sheet ~eeA; ng routine 400 (Fig. 7) is not implemented. Rather, the routine 300 (Fig. 6) loops to step 321 to start c~unting the time delay t-d (Fig. 5), of 80 milliseconds, during which a sheet 22 (Fig. 1) would normally be fed fr~m the time instant it is sensed by the sQnsor 99A to th~ time instant acceleration o~ the postage printing drum 64 is commenced, followed by implementing ~he step 322 of setting the shutter bar routine flag l'on", and then implementing the remainder of the main line program 300, including driving the drum 64 through a single revolution.

Accordingly, after setting the calibration flag, step 906 (Fig. 13), causing the main line program 300 (Fig. 6) to be concurrently implsmented, the routine 900 (Fig. 13~
implement~ the step 908 of deteL ining whether or not the postage meter trip cycle is complete, that is, determining whether or not the postage meter trip cycle complete flag has been set, step 378 (Fig. 6). Thus the program 900 (Fig.
13) deteL ;nes whether or not the last transition signal 240 (Fig. 2) has been received by the microprocessor 122, indicating that the trailing edge 244 (Fig. 4) of the printing lobe 226 has been detected by the sensor 232 and thus that the drum 64 (Fig. 1) has been returned substantially to its home position. Assuming that the routine 900 (Fig. 13~ makes a determination that the trip cycle is not complete, step 908, then, the routine 900 continuously loops through step 908 until the trip cycle is complete. ~hereupon the routine 900 implements the step 910 of ~etermining whether or not the measured, actual, time interval, from the time instant o~ commencement of constant 54 -- L~ , ", ", speed rotation of the drum 64 (Fig~ 2) tc the time instant that such constant speed rotation iB complete, is equal to the de~ired, predeter~ined, ti~e interval of 292 milliseconds corresponding to the pr~ferred, pxedeteL ine~
sheet feeding speed of 26 in~he~ per secon~. In this aonnection it i~ noted, as hereinhPfore discus~ed, in the course of implementation~ o~ the main line p,oy~ 300 (Fig.
6) a time interYal counter is cl0ared, in step ~56, to c -nc~ counting the actual time interval of constant printing speed of rotation of the drum 64, and, in step 363, upon completion of constant speed rotation, the actual time interval of duration thereof is stored. Accordingly, step 910 (Fig. 13) includes the step of fetching the stored, actual, time interval of duration of constant printing speed of rotation o~ the drum 64 for comparison with the desired time interval. Assuming that the measured and desired time intervals are equal, the routine 900 implements the step 912 of storing the desired reference voltage of step 904 as the reference voltage for, as hereinbefore discussed causing the drum 64 to feed and print postage indicia at the desired constant printing, and sheet feeding, speed, followed by the step 914 of returning processing to step 804 (Fig. 11) of the the power-up routine 800 for implementation of the main line program 804. On the other hand, assuming the measured and desired time intervals are not equal, step 910 (Fig.
13), then, the routine 900 implements the step 916 of calculating a new predetermined reference voltage which is either greater of less than the initial predetermined reference voltage of step 904, depending upon whether the measured time interval is less than or greater than the desired time interval. ~hereafter, the routine 900 implements a salected proaessing delay of for example 100 to 500 mill;.s~con~, step 918, to permit completion of implementation of other processing routines, including for example the shutter bar routine 500 (Fig. 8), followed by returning processing to step 905 (Fig. 13). Whereupon the routine 900 continuously successively implements steps 905, 906, 908, 910, 916 and 918 until the measured and desired time intervals are e~ual, step 91Q. At which time the - 55 ~

routine 900 then implements the ~uccessive steps 912 and 914 of storing the latest calculated reference voltage, step 916, which resulted in the s~a~red and desired time intervals being ~ound to be equal, ~tep 910, as the new, S desired, predetermined, reference voltage ~or ~ubsequent use by the microproce~sor 122 (Fig. 2) ~or providing the reference voltage signal 214 to the comparator 208 for causing the d.c. motor 180 to drive the drum 64 at the desir~d printing, and thus sheet feed~n~, speed of 26 inches pex second.

As shown in Fig. 1, assuming as is the normal case, each sheet 2~ fed to the mailing machine base 12 is urged by the operator into engagement with the registration fence 95 for guidance thereby downstream in the path of travel 30 to the input feed rollers 42 and 44. Whereupon the sheet 22 is fed downstream by the rollers 42 and 44, in the path of travel 30, with the inboard edge 96 (Fig. 2) thereof disposed in engagement with the registration fence 95 (Fig.
1) and is detected by the sheet feeding trip structure 99.
Accordingly, the leading edge 100 of each sheet 22 is fed into blocking relationship with the sheet fee~;n~ trip sensor 99A. And, as shown in Fig. 14, since the sensor 99A
is located closely alongside of the registration fence 95, the portion of the leading edge 100 of the sheet 22 which is next adjacent to the inboard edge 96 thereof is detected by the sensor 99A. Moreover, as the leading edge 100 of the sheet 22 is progressi~ely fed downstream in the path of travel 30, the magnitude of the analog voltage signal 135 (Fig. 1) provided to the microprocessor 122 by the sensing structure 99 changes from an unblocked voltage maximum Vum (Fig. 15) to a blocked voltage minimum Vb o~ nominally zero volts. Further, the transitlon time interval Tt durinq which the voltage magnitude V135 o~ the aforesaid signal 135 changes from 75% of the unblocked voltage -~; Vum to 25%
thereof is normally substantially 100 microseconds.

As shown in Fig. 16, wherein the inboard edge 96 of a given ~heet 22 being fed downstream in the path of travel 30 - 56 ~ "~"~

is typically ~kewed, relative to the registration fence 95, the leading end of the inboard edge 96 is spaced outwar~ly from the registration fence 95. And, due to the sen~or 99A
being located clo~e to the regi~tration fenc~ 95, the inboard edge 96~ ra~her than the leading edge 100, of the sheet 22 is fed into blocking relationship with the sensor 99A. Since the sensor 99A is then more gradually blocked by the inboard edge 96 of the moving ~heet 22 than it is when the le~i n~ edge 100 (Fig. 14~ thereo~ is fed into blocking relationship with the sensor 99A, the transition time interval Tt (Fig. 17) during which the voltage magnitude V135 of the aforesaid ~ignal 135 changes from 75% to 25% of the ~ unblocked voltage Vum increases.

With the above thoughts in mind, according to the invention the microprocessor 122 (Fig. 1) is preferably programmed to successively sample the signal 135 at two millisecond time intervals and to prevent operation of the postage meter 14, if during any two successive sampling tlme intervals the voltage magnitude V135 (Fig. 17) o~ the aforesaid signal 135 is equal to or less than 75% of the m unblocked voltage but not less than 25% of the ~-Yi unblocked voltage Vum, in order to prevent improperly locating the postage indicia imprintation on the sheet 22. To that end, as ~ereinbefore discll~se~, the main line program 300 (Fig. 6) preferably includes the step 316A
of setting the skew detection routine flag "on", for calling up and implementing a sheet skew detection routine, whenev~r the main line program 300 is impleme~ted. And, the microprocessor 122 (Fig. 1) ls preferably progL~ to include the sheet s~ew detection routine 1000 shown in Fig.
18.

As shown in Fig. 18, the sheet skew detection routine 1000 pre~erably com ~n~ with the step 1010 of sampling the voltage magnitute V135 of the signal 135 (Fig. 1~ from the sheet trip sensor 99A, ~ollowed by the step 1012 (Fig. 18~
of determining whether or not the samplsd voltage magnitude V135 is greater than 75~ of the ~i m unbloaked voltage - 57 - ~$~J ~ 4~ :?~:~

Vum. Assuming a ~heet 2;2 (Fig. 14) has not been fed into blocking relationship with the sensor 99A, the inquiry o~
step 1012 (Fig, 18) will be affirmative, and the routine lOOo will implement the step 1014 of storing data in a predetermined, first, or ~lag No. 1, ragister of the microproc~sor 122 (Fig. 1), indicating that the ~en~or g9A
i~ unblocked, A~L . i ~ however that the voltage magnitude V13~ of the sen-~or voltage signal 135 is not greater than 75~ of the maximum u~blo~ked voltage vu~, step 1012 (Fig.
lo 18), as would be the case i~ a sheet 22 (Fig. 14) were fed into blocking relation6hip with the sensor s9A, then, the routine 1000 i(Fig. 18) implements the ~tep 1018 of determining whether the actual voltage magnitude V135 of the signal 135 is less than 25% of the unblocked voltage 9~i Vum. Assuming that the sheet 22 (Fig. 14) which was fed into blocking relationship with the sensor s9A is not skewed relative to the registration fence 95, or that the sample voltage magnitude V135 (Fig. 15) was not made within the loo microsecond transition time interval when the voltage magnitude V135 changed from 75% to 25% of the unblocked voltages maximum Vum, then, the inquiry of step 1018 (Fig.
18) will be af~irmatively answered. Whereupon the routine 1000 implements the step 1020 of storing data in the aforesaid flag No. 1 register indicating that the sensor s9A
is blocked. If however a determination is made in step 1018 that the sample voltage magnitude V135 is not less than 25%
of the maximum unblocked voltage Vum, then, the routine lOoo assumes that the sample voltage magnitude ~135~ which caused the inquiry of step 1012 to indicate that a sheet 22 had heen Ped into blocking relationship with the sensor 99A, was made at a time instant when the sheet 22 was either within the 100 microsecond transition time interval Tt as shown in Fig. 15 or within a greater transition time interval Tt as shown in Fig. 17. Accordingly, the routine loo implements the step 1022 (Fig. 18~ of storing data in the ~lag No. 1 register to indicate that the sample voltage magnitude V135 is within the transition time interval T~, or equal to 25%
to 75% of the maximum unblocked voltage Vum. That i5, the routine lOoo stores data correspon~n~ to a potential skew condition, SK, in the flag No. 1 register.

After implementation of the appropriate ~tep 1014, 1020 or 1022 (Fig. 18), of storing an unblocked sensor, blocked sensor or potential sk~wed sheet condition, in the flag No.
1 register, then, the routine 1000 implements the step 1024 of delaying processing ~or a two millisecond time interval followed by repeating the voltage sampling and analysis processing hereinbefore discu~ed, but storing the results thereof in a second, predet~r~ined, register. More particularly, the routine 1000 implements the step 1026 of again sampling the voltage magnitude V135 of the sheet feed trip sensor signal 135 (Fig. 1), followed by again deteL i ni n~ in step 1028 whether the sample voltage magnitude V135 is greater than 75% of the -~; unblocked voltage Vum. Assuming that the inquiry of step 1028 is af~irmative, indi-.ating that the sensor 99A is not blocked, the routine 1000 implements the step 1030 of storing data corresponding to an unblocked sensor 99A in a secon~, predete- ;ne~ r sr flag No. 2, register. On the other hand, assuming that the inquiry of step 1028 is negative, indicating that the sensor 99A is blocked, then, the routine 1000 implements the step 1032 of detel in;ng whether the sample voltage magnitude V135 is less than 25% of the unblocked voltage maximum Vu~. As previously discussed, assuming that the sheet 22 found to have blocked the sensor 99A in step 1028 is either not skewed or is not within the 100 microsecond transition time interval, then, the $nquiry of step 1032 will be affirmative, and the routine 1000 will implement the step 1034 of storing data corresponding to a blocked sensor condition in the flag No. 2 register. On the other hand, if the inquiry of step 1032 is negative, indicating that the sheet 22, found to hav~ blocked the sensor 99A in step 1028, is within the transition time interval Tt ~Fig. 15 or 17), then, the routine 1000 implements the step 1036 o~ storing data in the flag No. 2 register indicating that the sheet 22 is within the ~ 3~
transit~n time interval Tt and thu~ that a potential ~kew condition exists.

After implementation o~ the appropriate step~ 1030, 1034 or 1036 (Fig. 18) of storing data correspnn~;ng an unblocked or blocked sensor condition, or potential skewed sheet condition, in th~ ~lag No. 2 regi6ter, then, the routine 1000 implements the step 1038 of deteL ~nin~ whether ox not both the flag No. 1 and ~lag No. 2 registers have potential skew condition data stored therein. ~hu~, the routine 1000 dat~ ~ ne8 whether._.two s~ccessive sample voltage maqnitudes V135 of the sheet feeder trip signal 135, made at time instants separated by substantially two milliseconds, both indicate that a sheet 22 is disposed is partial blocking relationship with the sens~r 99A, to determine whether or not the sheet 22 is skewed as shown in Figs. 16 and 17. Accordingly, assuming that both registers have potential skew data stored therein, ~tep 1038, the routine 1000 implements the step 1040 of setting a skew flag for the main llne program, which, as shown in Fig. 6, at step 317, resul~s in the main line program 300 implementing the step 317A of setting a machine error flag and causing the keyboard lamp 266 to co ?n~e blinking, followed by causing the microprocessor 122 to implement the conventional shut-down routine 340 and, thereafter, the successive steps 340 and 344 hereinbe~ore discussed. If however, one or the other or both of the flag No. 1 and No. 2 regiaters do not have data corresponding to a potential skew condition stored therein, step ~038 (Fig. 18), then, the routine 1000 implements the step 1042 of dete~ i ning whether the flag No.
2 register has data corresponding to a blocked sensor condition stored therein. Assuming the flag No. 2 register data corresponds to a blocked sensor condition, indicating that the sheet 22 i~ not within the transition time interval Tt (Fig. 17), and thu~ that the sheet 22 is not skewed, the routine 1000 implements the step 1044 of setting the sheet feeder trip signal flag for the main line program, which results in the main line program 300 (Fig. 6) determining, in step 318, that the flag is set, followed by implementing - 60 - 2~

successive steps nor~ally resulting in causing po tage indicia to he printed on the ~heet 22. On the other hand, if the inquiry of step 1042 is negatively an wered, that i5, the routine 1000 deter~ines that the data in the flag No. 2 register does not correspond to a blocked sensor condition, indicating that a sheet 22 is not being fed in path of travel 30 to the po~tage meter 14, the routine 1000 implements the step 1046 of clearing the sheet feeder trip signal flag for the main line ~OyL~. WheLeu~on the main line program 300 (Fig. 6~ determine~ in step 31~3, that the sheet feeding trip signal ~lag t 8 not ~et, followed by causing the successive steps 316, 316A, 317 and 318 to be implemented until either the skew flag is set, step 317, before the trip signal flag is set, step 318, or the trip signal flag is set, step 318, before the skew flag is set, step 317, as hereinbefore discussed in greater detail.

Accordingly, the routine 1000 (Fig. 18) is constructed and arranged to~sample the signal voltage magnitude V135 at two millisecond time intervals and to either implement the step 1040, of setting the skew flag to cause the main line program 300 to enter into a shut-down routine rather than cause postage indicia to be pri~ted on the skewed sheet 22, or the step 1044,, of setting the sheet feed trip signal flag to cause the main line program 300 to enter into processing eventuating in causing postage indicia to be : prin~ed on an unskewed sheet 22, or the step 1046, of clearing the ~heet feed trip signal flag to cause the main line program 300 to e~ter into a processing io~p until either a skewed or an unskewed sheet 22 is fed to the machine 10. Thereafter, the routine 1000 implements the step ~048 of copying, i.e., transferring, the contents of the flag No. 2 registar into the flag No. 1 register, ~ollowed by returning processing to step 1024 for implementation of the two millisecond time delay before again sampling the signal voltage magnitude V135, followed by the successive steps 1026-1048 inclusive, as hereinbefore discussed.
Accordingly, the routine 1000 is also constructed and arranged to ensure that each successive 2 millisecond 2 ~
sampling of the ~ignal voltage magnitude V135 is suocessively compared in step 1038 to the previous sample voltage magnitude V135 in order to ~lc~-essively det~ ine whether or not a given sheet 22 ~Fig~. 14, 15, 16 and 17~
fed into blocking ~elationship with the sensor 9~A is or is not a skewed sheet 22.

As shown in Fig. 19, wherein the inb~ard edge 96 of a given sheet 22 bei~g fed downstream in the path of ~ra~el 30 is atypically skewed~ relati~e t~ the registration fence 95, lo the trailing end o~ the inb~ard edge 96 is spaced outwardly from the registration fence 95. And, although the leading edge 100 o~ the sheet 22 is ~ed into blocking relationship with the sensor 99A, the inboard edge 96, rather than the trailing edge lOOA, of the heet 22 is fed out of bloc~ing relationship with the sens~r 99A. Under such oiL~ ~ances and, more generally, whenever the overall length Lo ~Fig. 14 or 1~ of a given sheet 22, as measured in the diraction of the path of travel 30, is less than a predetermined minimum length, corresponding to a predetermined minimum, sheet-length transition time interval Ttl (Fig. 20) o~
substantially 80 millis~co~ , during which the voltage magnitude V135 of the sheet feed trip signal 135 changes from 25% of the maximum unblocked voltage Vum to 75% of the -~; unblocked voltage Vum, the overall sheet length Lo is insufficient for postage printing purposes.
:
With the above thoughts in mind, according to the invention, the microprocessor 122 (Fig. 1) i8 preferably pLOyL ~1 to prevent operation of the postage meter 14, if a sheet 22 ~Fig. 19) fed into blocking relationship with the sensor 99A is fed out o~ blocking relationship with the sensor 99A before the end of a predetermined time interval of substantially 8Q milliseconds. Thus the mailing machine 10 is preferably provided with short sheet length detecting structure. More particularly, as here;nhefore noted in the course of discussing the main line program 300 (Fig. 6), the main line program 300 is constructed and arranged, through the implementation of steps 321 and 328 thereof, to - ~2 delay commencement of acceleration of the postage printing drum 64, step 330, for a t~me interval of substantially 80 milliseconds, after a sheet 22 i8 fed into blocking relationship with the sensor 99A, causing the sheet ~eeding trip signal flag to be set, step 318, to permit the shutter bar 68 to be moved out of locking engagement with the drum dri~e gear 66, steps 322 and 324, and to permit the sheet 22 to be fed down~tream in the path of travel 22, from the sensor 99A, for engagement by the postage printing drum 64.
Further, as previously noted, when the substantially 80 millisecond time interval has ended, step 328, the program 3~0 implements the step 329, corresponding to step 318~ o~
determining whether the sheet feed trip signal ~lag is set.
Thus, according to the invention, the microprocessor 122 preferably makes a determination as to whether the sheet 22 ~ound to be disposed in blocking relatio~h;p with the sensor 99A, causing the inquiry of step 318 to be affirmatively answered, is still in blocking relationship with the sensor 99A after the predeterminad intervening time delay, steps 321 and 328, of substantially 80 millise~onds.
Assumin~ as is the normal case that the inquiry of step 329 is affirmative, then, the program 300 implements the step 330 of setting the postage meter acceleration and constant velocity routine flag "o~", followed by initiating processing which, as hereinbefore discussed in detail, normally eventuates in the postage meter 14 printing postage indicia on the sheet 22. On the other hand, if the inquiry of step 329 is negative, indicating that the sheet 22 (Fig.
19) is no longer disposed in blocking relationship with the sensor 99A, then, the main line pro~ram 300 (Fig. 6) preferably implements the step 329A of setting a machine error flag and GaUSing the keyboard lamp 266 to commence bl;nk;~1, followed by causing the microprocessor 122 to implement the conventional shut-down routine 340 and, thereafter, the successive steps 340 and 344, hereinbe~ore discussed in detail.

Accordingly, the main line program 300 is constructed and arranged to sample the signal voltage magnitude V135 - ~3 - ~ 3 (Fig. 20) both before and a~ter a substantially 80 millisecond time delay td (Fig. 5) and to enter into a shut-down routine rather than cause postage indicia to be printed on the sheet 22, if the secon~ sample voltage magnitude V135 indicates that the overall longitu~in~
length Lo of the sheet 22 (Fig. 14 or 18), as measured in the direction of the path of travel 30, is not more than a predetermined length of substantially two inches. In this connection it is noted that ~ ing that a given, atypical, sheet 2~, exempli~ied by the atypically skewed sheet 22 shown in Fig. 19, is fed downstream in the path o~ travel 30 at the prePerred, design criteria, speed of substantially 26 inches per second, the sheet 22 will be fed into and out of blocki ng relationship with the sensor 99A during a sheet-length, transition time interval Ttl of substantially 80 milliseconds, which corresponds to an overall sheet length Lo (Fig. 19), as measured in the direction oP the path of travel 30, of substantially two i nches .

Claims

1. A mailing machine base including a sheet feeding apparatus, said sheet feeding apparatus comprising:

(a) means for feeding a sheet having a leading edge and a trailing edge in a path of travel, the sheet feeding means including a roller, the sheet feeding means including means for driving the roller at a desired sheet feeding speed corresponding to a desired reference voltage;

(b) means for controlling the sheet feeding means, the controlling means including a microprocessor connected to the roller driving means, the controlling means including means for sequentially sensing the leading and trailing edges of the sheet in the path of travel and providing corresponding successive signals to the microprocessor;

(c) the sheet having a predetermined length from the leading edge to the trailing edge thereof; and (d) the microprocessor programmed for 1.) providing a predetermined reference voltage corresponding to the desired sheet feeding speed,

2.) counting a time interval in response to receiving the successive leading and trailing edge signals, - 64a -

3.) determining whether the counted time interval and the desired time interval are substantially equal, and

4.) Storing the predetermined reference voltage as the desired reference voltage if the counted and desired time intervals are substantially equal.

2. The mailing machine base according to Claim 1, wherein the microprocessor is programmed for changing the predetermined reference voltage to a new predetermined reference voltage if the counted and desired time intervals are not substantially equal.

3. The mailing machine base according to Claim 1, wherein the microprocessor is programmed for storing the desired time interval.

4. The mailing machine base according to Claim 1 including a non-volatile memory for storing the desired reference voltage.

5. The mailing machine base according to Claim 1, wherein the sheet is a cut tape.

6. The mailing machine base according to Claim 1, wherein the microprocessor is programmed for calculating a new predetermined reference voltage if the counted and desired time intervals are not substantially equal.

7. The mailing machine base according to Claim 6, wherein the microprocessor is programmed for repeating steps 2 and 3 if the new predetermined reference voltage is calculated, and the microprocessor is programmed for storing the new predetermined reference voltage as the desired reference voltage if the counted and desired time intervals are substantially equal when steps 2 and 3 are repeated.

8. The mailing machine base according to Claim 1, wherein the predetermined reference voltage was previously stored as the desired reference voltage, and the programming for providing the predetermined reference voltages includes fetching the predetermined reference voltage.

9. The mailing machine base according to Claim 1, wherein the microprocessor is programmed for causing the roller driving means to start driving the roller at a sheet feeding speed corresponding to the predetermined reference voltage, and the microprocessor is programmed for causing the driving means to stop driving the roller if the predetermined reference voltage is stored as the desired reference voltage.

10. The mailing machine base according to Claim 9, wherein the microprocessor is programmed for causing the roller driving means to start driving the roller at a sheet feeding speed corresponding to the predetermined voltage, the microprocessor is programmed for causing the driving means to drive the roller at a sheet feeding speed corresponding to the new predetermined reference voltage after the new predetermined reference voltage is calculated, and the microprocessor is programmed for causing the driving means to stop driving the roller if the new predetermined reference voltage is stored as the desired reference voltage.

11. The mailing machine base according to Claim 1 including switching means connected to the microprocessor and operable to permit the microprocessor to implement steps 1 - 4 when the sheet is fed to the base.

12. The mailing machine base according to Claim 11, wherein the switching means includes a manually operable test key normally inaccessible to an operator of the base, and the test key is normally accessible to and operable by the manufacturer of the base.

13. A mailing machine comprising:

(a) a base and a postage meter mounted on the base, the postage meter including a rotary postage indicia printing drum, the base including means for driving the drum at a desired constant indicia printing speed corresponding to a desired reference voltage;

(b) the base including means for controlling the postage printing drum, the controlling means including a microprocessor connected to the drum driving means, the controlling means including means for sequentially sensing a commencement and a completion of constant printing speed of the drum and providing corresponding successive signals to the microprocessor;

(c) the microprocessor programmed for 1.) providing a predetermined reference voltage corresponding to the desired drum printing speed, 2.) counting a time interval in response to receiving the successive constant speed commencement and completion signals, 3.) determining whether the counted time interval and the desired time interval are substantially equal, and 4.) storing the predetermined reference voltage as the desired reference voltage if the counted and desired time intervals are substantially equal, and (d) further comprising a switching means connected to the microprocessor, said switching means including a manually operable test key normally inaccessible to an operator and normally accessible to a manufacturer of the base, the switching means including a print key normally accessible to the operator of the base, and the microprocessor being - 67a -programmed for bypassing a sheet feeding mode of operation thereof when both the test key and print key are operated.

14. The mailing machine according to Claim 13, wherein the microprocessor is programmed for changing the predetermined reference voltage to a new predetermined reference voltage if the counted and desired time intervals are not substantially equal.

15. The mailing machine according to Claim 13, wherein the microprocessor is programmed for storing the desired time interval.

16. The mailing machine according to Claim 13 including a non-volatile memory for storing the desired reference voltage.

17. The mailing machine according to Claim 13 wherein the drum includes a peripheral surface having a substantially arcuately-extending indicia printing portion, and the sensing means including means for sensing commencement and completion of rotation of the printing portion through a printing position thereof for providing the signals.

18. The mailing machine according to Claim 13, wherein the microprocessor is programmed for calculating a new predetermined reference voltage if the counted and desired time intervals are not substantially equal.

19. The mailing machine according to Claim 18, wherein the microprocessor is programmed for repeating steps 2 and 4 if the new predetermined reference voltage is calculated, and the microprocessor is programmed for storing the new predetermined reference voltage as the desired reference voltage if the counted and desired time intervals are substantially equal when steps 2 and 4 are repeated.

20. The mailing machine according to Claim 13, wherein the programming for providing the predetermined reference voltage includes fetching the predetermined reference voltage.

21. The mailing machine according to Claim 13, wherein the microprocessor is programmed for causing the drum driving means to start driving the drum at a printing speed corresponding to the predetermined reference voltage, and the microprocessor is programmed for causing the driving means to stop driving the drum if the predetermined reference voltage is stored as the desired reference voltage.

22. The mailing machine according to Claim 21, wherein the microprocessor is programmed for causing the drum driving means to start driving the drum at a printing speed corresponding to the predetermined voltage, the microprocessor is programmed for causing the driving means to drive the drum at printing speed corresponding to the new predetermined reference voltage after the new predetermined reference voltage is calculated, and the microprocessor is programmed for causing the driving means to stop driving the drum if the new predetermined reference voltage is stored as the desired reference voltage.

23. The mailing machine according to Claim 13 including switching means connected to the microprocessor and operable to permit the microprocessor to implement steps 1 - 4 without feeding a sheet to the machine.

24. The mailing machine according to Claim 23, wherein the switching means includes a manually operable test key normally inaccessible to an operator and normally accessible to a manufacturer of the base, the switching means including a print key normally accessible to the operator of the base, and the microprocessor is programmed for bypassing a sheet feeding mode of operation thereof when both the test key and print key are operated.