EP0476918A2 - Frankiermaschine - Google Patents

Frankiermaschine Download PDF

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Publication number
EP0476918A2
EP0476918A2 EP91308288A EP91308288A EP0476918A2 EP 0476918 A2 EP0476918 A2 EP 0476918A2 EP 91308288 A EP91308288 A EP 91308288A EP 91308288 A EP91308288 A EP 91308288A EP 0476918 A2 EP0476918 A2 EP 0476918A2
Authority
EP
European Patent Office
Prior art keywords
drive
gear
drum
assembly
drum shaft
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP91308288A
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English (en)
French (fr)
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EP0476918B1 (de
EP0476918A3 (en
Inventor
Hugh Mcchesney
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Pitney Bowes PLC
Original Assignee
Pitney Bowes PLC
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Filing date
Publication date
Application filed by Pitney Bowes PLC filed Critical Pitney Bowes PLC
Publication of EP0476918A2 publication Critical patent/EP0476918A2/de
Publication of EP0476918A3 publication Critical patent/EP0476918A3/en
Application granted granted Critical
Publication of EP0476918B1 publication Critical patent/EP0476918B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G07—CHECKING-DEVICES
    • G07B—TICKET-ISSUING APPARATUS; FARE-REGISTERING APPARATUS; FRANKING APPARATUS
    • G07B17/00—Franking apparatus
    • G07B17/00459—Details relating to mailpieces in a franking system
    • G07B17/00508—Printing or attaching on mailpieces
    • G—PHYSICS
    • G07—CHECKING-DEVICES
    • G07B—TICKET-ISSUING APPARATUS; FARE-REGISTERING APPARATUS; FRANKING APPARATUS
    • G07B17/00—Franking apparatus
    • G07B17/00459—Details relating to mailpieces in a franking system
    • G07B17/00508—Printing or attaching on mailpieces
    • G07B2017/00516—Details of printing apparatus
    • G07B2017/00524—Printheads
    • G07B2017/00548—Mechanical printhead

Definitions

  • This invention relates to a postage meter.
  • postage meter in this specification is used to mean any franking machine or value symbol issuing meter which can apply symbols or legends to articles which denote a particular value, which may for example be the cost of transporting the article to a defined destination, and which also keep a secure cumulative record of value dispensed.
  • the term is not intended to be restricted to the issuing of value in connection with transport of mail pieces by the Postal authorities.
  • Postage meters as described herein could be employed equally well by private couriers.
  • a value symbol or legend may be any of one or more digits making up a number, one or more alphabetical symbols, other geographical symbols, or magnetically or electrically or optically readable symbols.
  • a typical postage meter includes the following principal components: a means of printing selectable value symbols, a means of keeping account of value symbols printed, and a keyboard or other input means whereby a user can set the amount of value which the machine is to print.
  • An aim of the invention is to provide a compact and easily assembled, yet secure and efficient, postage meter.
  • a postage meter comprising: a rotatable print drum for franking an article, the print drum including settable value-denoting elements and being mounted on a drum shaft for rotation therewith; a series of driving elements each connected to drive a respective one of the value-denoting elements via an intervening drive train; and a gearbox housing within which the drive trains are housed; characterised in that the gearbox housing is split and is appropriately shaped so that it can be mounted on and supported by the drum shaft.
  • the meter further comprises linearly-movable racks located (in known manner) in at least one groove in the drum shaft, each rack being driven by a drive gear which forms the final gear of a respective one of the drive trains.
  • each rack being driven by a drive gear which forms the final gear of a respective one of the drive trains.
  • each drive train includes an encoder disc provided with gear teeth on its perihery and which serves to transmit drive from the driving element (e.g. motor) to gears downstream in the drive train.
  • the driving element e.g. motor
  • a franking machine having a print drum assembly including a print drum and a drum shaft which substantially wholly supports a gearbox containing means for adjusting the position of value-denoting elements within the print drum.
  • the postage meter 1 is intended to be capable of being used with a range of known postage meter bases 2.
  • the postage meter 1 comprises a main cover 3, a hingeable drum cover 4 and a carrying handle 5.
  • the drum cover 4 is pivotable to expose a print drum which prints postage. The print drum will be described later.
  • postage is printed on a mailpiece by passing the mailpiece along a path P running along the top of the postage meter base 2 and underneath the print drum.
  • the postage meter 1 also includes a power input socket 6 and an on-off switch 7.
  • Buttons 131 of a key pad 13 are accessible at the top of the postage meter 1 in order to control the functioning of the postage meter.
  • the buttons 131 are used to input the amount of postage to be printed on the mailpiece; to check the value of the ascending register of total postage value printed; to check the descending register of remaining postage valve available for use; to control the replenishment of postage value stored in the meter; to enter and subsequently use memory functions such as frequently used postage values; and to perform other control and diagnostic functions.
  • a display 14 is provided in order to present information to the user.
  • a slidable knob 8 is provided for controlling a multi-slogan change device on the print drum. Further details are given later.
  • main internal units Within the main cover 3 are located two main internal units: an upper internal unit and a lower internal unit.
  • the upper internal unit contains logic circuitry including a computer for controlling postage meter functions.
  • FIGs 2a-2g illustrate the components of a first assembly 10.
  • the subject matter of Figures 2, 3 and 4 is embodied in our U.K. Patent Application Publication No. 2,236,627. No claim to this subject matter is made in the present application.
  • the upper internal unit is made up of a first assembly 10 (Fig. 4) and a second assembly 20 (Fig. 4).
  • the first assembly 10 comprises a first die casting 12 having a front wall 12a, a rear wall 12b, side walls 12c and 12d, and a top wall 12e.
  • the top wall 12e has apertures therein.
  • the next component of the first assembly is the key pad 13 having an aperture 13a therein.
  • Beneath the key pad 13 is positioned the display 14 and a display printed circuit board 14a.
  • the display 14 is connected to a flying ribbon 14b.
  • An insulating plate 15 is located beneath the board 14a and beneath this is located a metal support plate 16.
  • the parts 12, 13, 14a, 15, 16 have aligned holes 16a therein, so that they can be connected together as a unit by suitable screws of bolts.
  • One such bolt is illustrated in Figure 2g.
  • the second assembly 20 comprises a second die casting 22, a main logic board 24, and a power supply unit 26. These are all seen in Figure 3.
  • the second die casting is a generally planar die casting of a particular shape designed to co-operate and interfit with the first die casting 12. For this purpose it has an upstanding rim 22a and is provided with appropriately positioned through holes 22b.
  • the main logic board has through holes 24b which are aligned in registry with the holes 22b of the die casting, so as to permit assembly.
  • a so-called "Taptite" screw 24a for effecting this connection is shown at the top of Figure 3. Three other screws (not shown) are also used.
  • the second die casting 22 also has through holes 22c which are arranged in registry with holes 26c in printed circuit board 26a which is attached to the power supply unit 26.
  • the holes 22c, 26c permit assembly using screws.
  • Figure 4 illustrates the two assemblies 10 and 20, and this figure also shows side plates 30 which are attached to the second die casting 22 by self tapping screws 32.
  • the screws 32 may be "Taptite" screws.
  • the plates 30 are of metal and serve as part of a heat sink which includes the die casting 22 and, to a lesser extent, the die casting 12. The close physical connection between the parts 12, 22 and 30 permits heat generated in the power supply unit 26 to be effectively dissipated so avoiding undesirable over-heating.
  • the parts 12, 22 and 30 also provide shielding against radio frequency interference and electromagnetic induction effects which might affect the working of the components on the main logic board 24.
  • the lower internal unit includes a base unit 40 which forms the overall base of the postage meter 1 and which is, in use, positioned on top of the underlying postage meter base 2 with which the postage meter 1 is used (see Figure 1).
  • the base unit 40 comprises a base plate 41 and two upwardly extending walls 42.
  • a latch mechanism 50 of generally known design is mounted on the base plate 41 and includes three tumblers 51 which receive upwardly extending projections of the postage meter base 2 when the postage meter 1 is mounted thereon. The projections of the postage meter base 2 are locked into the tumblers 51 by movable plates 52. This arrangement follows a known design.
  • the walls 42 of the base unit 40 contain concave bearing support surfaces 43 and 44.
  • the bearing support surfaces 43, 44 receive, in the assembled postage meter, rear and front bearings 61 and 62 respectively of a print drum assembly 60 (see Figure 5).
  • the bearings 61, 62 rotatably support a print drum 63 and drum shaft 64 which rotate together.
  • the print drum 63 contains, in a known manner, a bank of five rotatable digit wheels 631. At any one time, each digit wheel 631 presents a selectable one of its digits 0 to 9 so that, by rotating all five wheels 631, a selected postage value may be displayed. Then, when the print drum 63 rotates, the displayed postage value may be printed on the mailpiece as it passes underneath the drum 63 along the path P (see Figure 1).
  • the digit wheels 631 are adjusted in a known manner by five longitudinally slidable racks 641 (see Figure 5) that are located in the drum shaft 64. Each rack 641 controls a respective one of the digit wheels 631, so that longitudinal movement of the rack is converted into rotational movement of the digit wheel. This changes the digit that the wheel presents for printing and thereby alters the postage value to be printed.
  • the drum assembly 60 includes a drive gear 65 for rotatably driving the drum shaft 64 and print drum 63.
  • the bottom part of the drive gear 65 projects through an aperture 45 (most clearly seen in Figure 7) in the base plate 41. This arrangement permits the drive gear 65 to be accessible to the postage meter base 2, when the postage meter 1 is mounted thereon, so that the postage meter base may rotatably drive the drive gear 65 and thereby cause rotation of the print drum 63.
  • the drum shaft 64 includes a toothed portion 642 adjacent to the drive gear 65.
  • This toothed portion 642 drives an encoder disc 46 which is rotatably mounted on the base plate 41 (see Figures 7 to 9).
  • the encoder disc has a circumference twice that of the toothed portion 642 and therefore completes a half revolution for every whole revolution of the print drum 63/drum shaft 64. Because it is desired to know when the print drum 63 has completed one revolution and returned to its "home" position, the encoder disc 46 is provided with two slots 461.
  • the slots 461 are on different radii and are approximately diametrically opposite one another.
  • a detector unit 47 straddles the rim of the encoder disc 46 so as to detect the slots 461 by means of interrupted light beam arangements.
  • the detector unit 47 is connected to the main logic board 24 so as to inform the circuitry in the logic board as to when the print drum 63 has completed a full revolution and returned to its home position.
  • a shutter bar 48 is slidably mounted on the base plate 41 and has an end 481 which projects into a slot 651 (see Figure 21) of the drive gear when the print drum 63 is in its home position. In this way, the print drum 63 is prevented from moving.
  • the shutter bar 48 is slid so as to retract its end 481 out of the slot 651 in the drive gear 65. This is done by a known mechanism (not shown) under the control of the main logic board 24.
  • the shutter bar 48 includes a projection 482 which extends into an interposer unit 49 so that the shutter bar 48 may be held locked in its locking position.
  • the interposer unit 49 must be activated by the main logic board 24 so as to release the projection 482.
  • the shutter bar 48 and interposer unit 49 have their positions optically sensed by optical sensor means (not shown).
  • the gearbox assembly 70 comprises a lower portion 71 and an upper portion 72. Both portions are made out of injection moulded plastics material.
  • the gearbox assembly is provided in order to drive the five racks 641 in the drum shaft 64.
  • a slot 643 in the drum shaft 64 in which three of the five racks are, in practice, located, although they are not actually shown in that Figure.
  • a corresponding slot on the underside of the drum shaft 64 as viewed in Figure 10 which contains the remaining two of the five racks 641.
  • the longitudinal position of the racks determines the rotational position of the corresponding five digit wheels in the print drum 63 so that the postage value to be printed may be varied.
  • the gearbox assembly contains two rack drive assemblies.
  • a first one of the rack drive assemblies 73 is located in the lower gearbox portion 71 and extends underneath the drum shaft 64 so as to drive the two lowermost racks 641.
  • An upper rack drive assembly 74 is located in the upper gearbox portion 72 and extends over the drum shaft 64 so as to drive the three racks 641 in the upper part of the drum shaft.
  • a splined drive shaft 741 having a generally pentagonal cross-section as shown in Figure 15, extends the full length of the drive assembly and is rotatably supported at both ends by snap-in bearing clips 742. These bearing clips 742 snap into slots 721 at both ends of the lower half of the upper gearbox portion.
  • Figure 11 shows one of the bearing clips 742 snapped into place in its respective slot 721.
  • the splined drive shaft 741 supports, starting from the left-hand end of the drive assembly as viewed in Figure 13, a first encoder gear 743, an outer half-shaft 744, an inner half-shaft 745, a first cross-over gear 746, a spacer 747, a second cross-over gear 748, a third cross-over gear 749, a spacer 7410, a second encoder gear 7411 and a third encoder gear 7412.
  • the encoder gears 743, 7411, 7412 are each driven by a respective motor, as will be described later.
  • Each one of the cross-over gears 746, 748, 749 is drivingly engaged with one of the three upper racks 641 of the drum shaft 64 when the drum shaft is in its "home” position as shown in Figure 10.
  • Each cross-over gear must be independently rotatable in order to permit independent adjustment of the three racks 641.
  • the third encoder gear 7412 and its associated cross-over gear 748 engage with the splined profile of the drive shaft 741 so that drive may be transmitted from the encoder gear 7412 to the cross-over gear 748 by means of the drive shaft 741 (drive path A in Figure 14).
  • the other components do not engage with the drive shaft 741 so that they are freely rotatable relative thereto. In this way, the encoder gear 7412 may drive its cross-over gear 748 without also at the same time causing rotation of the other components.
  • the second encoder gear 7411 is drivingly engaged with dogs 74101 of the neighbouring spacer 7410.
  • the spacer 7410 is also engaged via dogs 74102 with the third cross-over gear 749.
  • all three components are freely rotatable around the splined drive shaft 741 and thus drive may be transmitted from the encoder gear 7411 to its associated cross-over gear 749 by means of the intervening spacer 7410.
  • This provides a second drive path B which is independent of the first drive path A from the encoder disc 7412 to its cross-over gear 748.
  • the first encoder gear 743 is drivingly engaged with dogs 7443 of the outer half-shaft 744.
  • An internal bore 7441 of the half-shaft 744 has a non-circular cross section so that it drivingly engages a correspondingly profiled outer section of the inner half-shaft 745 which is received in the bore 7441.
  • rotational drive may be transmitted from the outer half-shaft 744 to the inner-half shaft 745.
  • the inner-half shaft 745 is engaged via dogs 7451 with the associated first cross-over gear 746 so as to pass the drive thereonto.
  • there is formed a third drive path C from the encoder disc 743 to the cross-over gear 746. All of the components 743, 744, 745 and 746 are freely rotatable about the splined drive shaft 741.
  • the encoder gears 743, 7411, 7412 are driven by motors 86, 88, 87 respectively (see Figure 13).
  • the spring 7442 also ensures that the two encoder gears 743, 7412 at the ends of the string of components assembled on the drive shaft 741 are axially biassed against the adjacent bearing clips 742. Because the strength of the sping 7442 may be varied, this permits the frictional resistance of the rotational drive between each encoder gear and its associated cross-over gear to be pre-set. The spring 7442 also ensures that the components which are engaged with one another via dogs do not introduce any backlash into the drive between the encoder gears 743, 7411 and their associated cross-over gears 746, 749.
  • All of the components of the rack drive assembly 74, except for the cross-over gears, are made out of plastics material.
  • the cross-over gears are made of metal in order to resist wear caused by driving the three uppermost racks 641.
  • the construction of the lower rack drive assembly 73 shown in Figures 10, 12 and 16 is analogous to that of the upper rack drive assembly 74 just described. The major difference is that the lower rack drive assembly 73, because it only has to drive the two lower racks 641, only has two encoder gears and two cross-over gears.
  • the lower rack drive assembly 73 has a splined drive shaft 731 that is rotatably mounted at both ends in snap-in bearing clips 732.
  • the clips 732 snap into slots (not shown) in the walls of the lower gearbox portion 71.
  • One of the bearing clips 732 when snapped into place is visible in Figure 10.
  • the following components are mounted on the splined drive shaft 731; a first encoder gear 733, a second encoder gear 734, an outer half-shaft 735, an inner-half shaft 736, a first cross-over gear 737, a second cross-over gear 738 and a spacer 739.
  • An axial biassing spring 7310 is also provided.
  • the encoder gears 733, 734 are driven by motors 81, 83 respectively.
  • the encoder gear 733 and cross-over gear 738 have profiles that complement the generally pentagonal profile of the splined drive shaft 731.
  • drive may be transmitted from the encoder gear 733 via the drive shaft 731 to the cross-over gear 738.
  • the remaining components are rotatably mounted on the drive shaft 731.
  • a first drive path D from the encoder disc 733 to its associated cross-over gear 738.
  • a second, independent drive path E is formed by the second encoder gear 734, the outer and inner half-shafts 735 and 736 and the first cross-over gear 737.
  • These components are freely rotatable around the drive shaft 731 and are linked together via dogs 7351 and 7361, with spring biassing, in a manner analogous to that of components 743 to 746 of the upper rack drive assembly 74, described above.
  • the lower rack drive assembly 73 therefore includes two drive paths, from the motors 81, 83, through the encoder discs 733, 734 and onto the cross-over gears 738, 737 respectively.
  • Each of the two cross-over gears 737, 738 independently drives a respective one of the pair of racks 641 in the lower half of the drum shaft 64 when the drum shaft is in its "home" position as shown in Figure 10.
  • Figure 17 shows how each encoder gear 743, 7411, 7412 of the upper rack drive assembly 74 and each encoder gear 733, 734 of the lower rack drive assembly 73 contains apertures which permit the rotational position of the encoder gear to be determined.
  • the arrangement shown in Figure 17 is a cross-section representative of the arrangement relating to the encoder gear 743 or the encoder gear 7411 of the upper rack drive assembly 74.
  • the arrangement in relation to the encoder gear 743 is described.
  • the arrangements for the other four encoder gears are analogous.
  • a dual channel interrupted light beam sensor 7413 (see Figure 11) is positioned in an aperture directly above the encoder gear 743.
  • the encoder gear 743 has an inner annular array of apertures 7431 and an outer annular array of apertures 7432.
  • the sensor located in the aperture straddles the encoder gear 743 so as to have a first light beam at the radial distance corresponding to the inner apertures 7431 and a second light beam positioned at the radial distance corresponding to the outer apertures 7432.
  • a detector is provided for each light beam so as to detect when it is and when it is not interrupted by the solid portions between the apertures associated with that light beam. The information from the two detectors is fed to the main logic board 24.
  • the encoder gear serves the two purposes of acting as a drive gear, as will be described in more detail later, and giving information regarding the position of the associated digit wheel 631.
  • the encoder gear 743 Because of the limited longitudinal movement of the rack 641 associated with the encoder gear 743, the encoder gear only ever rotates less than a single revolution.
  • the positions associated with the digits 0 to 9 of the associated digit wheel 631 are illustrated.
  • the encoder gear 743 When the encoder gear 743 is rotated so that the notional line associated with the indicated value 0 is pointing vertically upwards as viewed in Figure 17, then the associated digit wheel 631 will present the numeral 0 as its contribution to the postage value to be printed.
  • the notional radial line numbered 1 is pointing vertically upwards, the digit wheel 631 will present the numeral 1 for printing.
  • the digit wheel 631 may be rotated to present the numerals 2 to 9 for printing.
  • Each encoder gear is driven by its own motor. It is important that the rotational position of the encoder gear is accurately known so that, by means of feedback the motor may be used to accurately position the encoder gear at the correct rotational position associated with the numeral value desired to be presented on the digit wheel 631 for printing.
  • the apertures 7431 and 7432 enable this to be done. Assuming 1 to equate to no light being received by a detector, and 0 to equate to light being received by the detector, then the apertures 7431 and 7432 modulate the two light beams to produce a binary output from each of the two light detectors positioned to detect whether or not light is passing through the apertures 7431 and 7432. The two binary outputs combine to produce a quadrature-type output.
  • the two sets of apertures are arranged so that, as the encoder gear 743 rotates, the outputs of the two channels of the two detectors cycle in the following manner as the gear rotates through the 36° associated with moving the digit wheel 631 from one numeral value position (e.g. 2) to an adjacent numeral value position (e.g. 3): 00,01,11,10,00,01,11,10,00.
  • Each pair of outputs is in the following order: output from outer detector and then output from inner detector.
  • the apertures 7431, 7432 make it possible to resolve eight different positions as the encoder gear 743 rotates through 36°.
  • the encoder gear 743 therefore has a resolution of 41 ⁇ 2°. This gives and accuracy of ⁇ 21 ⁇ 4° about a desired position.
  • encoder discs in postage meters have had the apertures 7431, 7432 positioned at twice the circumferential pitch, thereby giving a resolution of 9° (i.e. 41 ⁇ 2° either side of a desired position).
  • the quadrature output at each position associated with a numeral is 00.
  • an output of 00 is also produced at the mid-points between the positions associated with the numeral values.
  • the system must know which of the outputs of 00 correspond to the numeral values and which correspond to the mid-points between the numeral values. This is determined during an initialisation routine when the equipment is first activated ("hard" initialisation).
  • the encoder gear is only able to move from the 0 position to the 9 position by rotating through the intermediate values 1 to 8. It is not able to move directly from 0 to 9. If the gear tries to rotate from 0 to 9, some movement will be possible but the rack 641 will then hit one of its end stops and no further movement will be possible. Likewise, should movement be attempted from 9 to 0, the rack 641 will hit the other one of its end stops after a small degree of movement and then no further rotation will be possible. Once an end stop has been reached, the encoder gear is rotated in the opposite direction and the detector is used to detect the first 00 quadrature output.
  • the logic circuitry assumes that this first 00 quadrature output corresponds to the 0 or 9 position.
  • this assumption will always be correct. For example, if the gear is rotating from 3 to 2 to 1 to 0 in order to find the end stop of the rack, there will be a 00 quadrature output at the 0 position and no further 00 quadrature output because the next such output is at the 9 position and that position cannot be reached from the 0 position. Thus, once the rack reaches its end stop and the encoder gear reverses direction, the first 00 quadrature output to be reached will be the one associated with the 0 position. Because the encoder gear offering 9° resolution only has ten 00 quadrature outputs, moving the rack 641 from end stop to end stop enables the 00 quadrature outputs associated with the 0 and 9 positions to be determined without any possibility of error.
  • the encoder gear 743 has two of its apertures 7431, 7432 blanked out between the notional lines associated with the 0 and 9 positions. Specifically, there is a blanked out one 7431′ of the apertures 7431 and a blanked out one 7432' of the apertures 7432.
  • the apertures chosen to be blanked out are those which thereby prevent the generation of a 00 quadrature output at any point between the 0 and 9 positions of the encoder gear 743. If the encoder gear were to be able to move fully between its 0 and 9 positions, the quadrature output would vary as follows: 00,10,11,11,11,11,11,01,00.
  • the tolerances of the whole assembly would have to be such that there was no possibility, during hard initialisation, of movement between the end stops of the rack 641 causing the production of a 00 quadrature output at the mid-point between the 0 and 9 positions. Because the arrangement shown in Figure 17 prevents a 00 quadrature output being produced at the mid-point, the tolerances of the whole assembly may be relaxed and be kept substantially the same as those associated with an encoder gear offering a 9° resolution instead of the 41 ⁇ 2° resolution as shown in Figure 17. Thus, the Figure 17 arrangement offers the improvement in resolution to 41 ⁇ 2° without the normally associated requirement to double the accuracy of the tolerances associated with manufacturing the whole assembly.
  • the encoder gear 743 is driven by its motor until it hits the end stop adjacent to the 9 position.
  • the gear is then rotated in the opposite direction.
  • the 00 quadrature outputs are detected as they occur and eventually the gear hits the end stop adjacent to the 0 position.
  • the gear is moved back to the first 00 quadrature output and the main logic board 24 treats this as the 0 position.
  • the gear carries on rotating up to the 9 position and then rotates back down to the 0 position. This enables the main logic board to check that there are the required ten positions associated with the 00 quadrature outputs.
  • the gear 743 is at the 7 position when the postage meter is turned off. This fact is stored in the main logic board 24.
  • a "soft" initialisation is performed in order to confirm that the gear 743 was still at the 7 position when the meter was turned back on.
  • the "soft" initialisation involves the gear motor rotating the gear up to the 9 position and then back down to the 0 position, with the extent of movement in both directions being based on the assumption that the gear had indeed remained at the 7 position all the time the postage meter was turned off. If the movement between the 0 and 9 positions is completed without hitting either end stop, then the main logic board 24 knows that it was correct to assume that the gear had remained at the 7 position during power down.
  • the soft initialisation is performed every time from the second power up onwards.
  • the first power up triggers a hard initialisation.
  • the dual channel sensor 7413 used to produce the quadrature output uses two light beams. Each beam is penerated by a light emitting diode (LED) and detected by a photodiode. It has been found that the edges of the apertures 7431, 7432 in the encoder gear 743 diffract any light beam that prazes past them. For each photodiode, this tends to make it more difficult to detect the transition between the light beam (i) passing through an aperture and (ii) being interrupted by the solid portions between the apertures.
  • LED light emitting diode
  • the diffraction phenomenon has a blurring effect, because, even when the line of sight between the LED and the photodiode is blocked by an inter-aperture solid portion, light is able to set off at an angle to the line of sight from the LED and be bent by the diffraction effect at the edge of the aperture so that it falls on the photodiode. In other words, the light follows a zigzag path.
  • the diffraction blurring is prevented by placing slots in front of each LED and its associated photodiode.
  • the slots ensure that only light that has travelled along the straight line from the LED to the photodiode will be able to impinge on the photodiode.
  • the lower and upper gearbox portions 71, 72 are made out of plastics material, there is the conflicting requirement of choosing a material which is easy to mould and gives good dimensional accuracy and which also is capable of acting as a bearing for a rotating shaft.
  • the parts of the gearbox assembly 70 which have to act as bearings for rotating shafts are produced as separate inserts which are clipped into place in the walls of the upper and lower gearbox portions 71, 72.
  • the upper and lower gearbox portions which are formed generally as compartmental housings, may be made out of 30% glass filled plastics material.
  • Each encoder gear is driven by a respective motor and reduction gear assembly.
  • the motor 81 drives the encoder gear 733 through a reduction gear assembly 82.
  • the motor 83 drives the encoder gear 734 through a reduction gear assembly 84.
  • the two motors 81, 83 are held in place by pairs of clips 811 and 831.
  • the individual gears of each reduction gear assembly 82, 84 are rotatably mounted in pairs of bearing clips 85.
  • Each bearing clip 85 has two circular apertures 851 for receiving the shafts of the associated reduction gear assembly.
  • the side edges of the clip 85 contain channels 852 which guide the clip 85 when it is slid into a slot 711 formed in the lower gearbox portion 71.
  • a flange 853 which contains an aperture 854.
  • the clip 85 reaches the bottom of the slot 711, the flange 853 rides up a ramp 712 provided adjacent to the bottom of the slot 711.
  • a web 8531 of the flange 853 snaps down round the back of the ramp 712 so as to prevent withdrawal of the clip 85 from the slot 711.
  • the motor 81 may be assembled with its associated clips 85 and reduction gear assembly 82 and then slotted down into the lower gearbox portion 71 to be retained in place by the clips 811 and by the clips 85 engaging with the associated slots 711 and their ramps 712.
  • the resulting positioning of the motor 81, clips 85 and reduction gear assembly 82 is as shown in Figure 10.
  • the splined drive shafts 731, 741 of the rack drive assembly 73, 74 are rotatably mounted in bearing clips 732, 742. These clips are clipped into slots (e.g. slot 721 in Figure 11) in the gearbox portions 71, 72.
  • a representative clip of this type is diagrammatically illustrated in Figure 19.
  • the bearing clip 742 has an aperture 7421 within which is rotably mounted the drive shaft 741.
  • the clip 742 also has a pair of wings 7422 which flex up and over ramps 722 as the clip 742 is inserted into the slot 721.
  • Figure 19 shows only half of the clip 742. The entire clip is shown in Figure 11.
  • the clips 85 are designed so that their channels 852 form a loose fit with the walls of the slot 711. In this way, the reduction gear assembly is able to move slightly so as to prevent binding up between itself and the associated encoder gear.
  • a suitable material for the snap-in clips is a combination of nylon and PTFE.
  • the upper gearbox portion 72 contains the motors 86, 87, 88 and respective reduction gear assemblies 861, 871, 881.
  • the motors and reduction gear assemblies of the upper gearbox portion are preassembled with snap-in bearing clips 85 and then slid down into the compartmental casing of the upper gearbox portion.
  • the motors 86, 87, 88 are held in place by respective pairs of clips 862, 872, 882.
  • the clips 85 are slotted down into respective pairs of slots 863, 873, 883 in a manner analogous to that described in relation to the lower gearbox portion.
  • the ramps positioned at the bottom of the slots 863, 873, 883 for holding in position the clips 85 are not visible in Figures 11 and 13. However, they are provided and have a construction similar to that of ramp 712 illustrated in Figure 18.
  • the motors 86, 87, 88 drive the encoder gears 743, 7412, 7411 respectively.
  • the purpose of the motors is to adjust the positions of the racks and hence alter the positions of the digit wheels in the print drum to the selected postage value set by the user pressing the buttons 131.
  • the lower gearbox portion 71 has a pair of arcuate recesses 713 for receiving plain bearings 66 which permit rotation of the drum shaft 64 and print drum 63.
  • the front bearing 62 is also provided and, as will be described later, this bearing is eventually seated in the bearing support surface 44 of the wall 42 of the base unit 40.
  • the drum shaft 64 has a further groove (not visible in the drawings) similar to the grooves 67 but located between the front bearing 62 (see Figure 10) and the adjacent plain bearing 66.
  • a pair of rack lock plates 68 extend into this extra groove when the print drum 63 is at its "home” position.
  • the rack lock plates 68 are arranged so that they do not interfere with the longitudinal movement of the racks 641 when the print drum 63 is at its "home” position. However, as soon as the print drum starts to rotate, the racks 641 are rotated into locking engagement with the rack lock plates 68. In this way, unwanted longitudinal movement of the racks 641 is prevented during each rotational cycle of the print drum 63.
  • the rack lock plates 68 also serve the function of longitudinally restraining the entire print drum shaft 64. Screws 714 are screwed through a side wall of the housing of the lower gearbox portion 71, through the rack lock plates 68 and into the front bearing 62.
  • the upper gearbox portion 72 is screwed and/or clipped onto the lower gearbox portion to result in the gearbox assembly 70 as illustrated in Figure 11 being disposed around the drum shaft 64 of the print drum assembly 60.
  • the lower and upper gearbox portions 71, 72 have respective bosses 715, 723 used to screw the two gearbox portions together.
  • the lower gearbox portion 71 is provided with four screw holes 716 (see Figure 12).
  • Figure 20 is a diagrammatic illustration of how the gearbox assembly 70 is supported on the base plate 41.
  • Figure 20 also shows how the gearbox assembly 70 is assembled around the drum shaft 64 of the print drum assembly 60. Essentially, the two gearbox portions 71, 72 are clamped around the drum shaft 64 and screwed together.
  • the print drum assembly 60 would be mounted on the base unit 40 and the gearbox assembly 70 would be separately mounted on the base unit 40. Because of this, tolerances had to be carefully controlled in order to ensure that the relative positioning of the print drum assembly 60 and gearbox assembly 70 was satisfactory. The tolerances between the gearbox assembly 70 and print drum assembly 60 have to be carefully controlled in order to prevent inaccurate engagement of the cross-over gears of the gearbox assembly with the racks of the print drum assembly.
  • the arrangement shown in the accompanying figures has the gearbox assembly 70 mounted directly on the print drum assembly 60.
  • the upper gearbox housing 72 and the lower gearbox housing surround and are supported by the drum shaft 64. This makes it easier to ensure that the cross-over gears of the gearbox assembly 70 engage accurately with the racks 641 of the print drum assembly 60.
  • the two assemblies 60, 70 form a single unit which is mounted as one on the base unit 40. This is done by positioning the front main bearing 62 in the bearing support surface 44 of the base unit 40.
  • the front bearing 62 has a pair of screw holes 621 so that it may be screwed onto the underlying base wall 42.
  • the other end of the drum shaft 64 carries the rear bearing 61 and this sits in the bearing support surface 43.
  • the gearbox assembly 70 is not directly mounted on the base unit 40. It is only indirectly mounted on the base unit 40 via the print drum assembly 60.
  • a pad 75 of resilient material is placed between the end of the lower gearbox portion 71 remote from the drum shaft 64 and a boss 53 of the base unit 40.
  • this pad 75 does not serve to determine the positioning of the gearbox assembly.
  • the position of the gearbox assembly 70 relative to the base unit 40 is determined by the positioning of the gearbox assembly 70 on the print drum assembly 60. This has the consequence that positioning the drum shaft assembly 60 on the saddles 43, 44 (Fig. 6) automatically results in the proper positioning of the gearbox relative to the base unit 40, as well as properly positioning the cross-over gears relative to the racks.
  • the limited backlash clutch is located partly within the rear bearing 61.
  • the rear bearing 61 has a circular bore 611 which rotatably supports the drum shaft 64.
  • the drive gear 65 which is supported on a hub 652 of a disc-like cam 653.
  • the slot 651 by means of which the shutter bar 48 is able to lock the print drum assembly 60 in its "home” position, extends through both the disc-like cam 653 and the drive gear 65.
  • the drive gear 65/disc-like cam 653 is non-rotatably mounted on the drum shaft 64 in order to permit this locking of the print drum assembly 60 in its "home” position.
  • the hub 652 also carries the toothed portion 642 described previously in relation to Figure 5.
  • the print drum assembly 60 When the print drum assembly completes a cycle comprising a single revolution, the print drum assembly 60 must be brought to a halt at a position at which the shutter bar 48 may move into the slot 651 so as to provide the locking action.
  • the postage meter base 2 contains a drive mechanism which drives the drive gear 65 to effect the rotation of the print drum assembly 60. Even when the drive mechanism of the postage meter base 2 is switched off at or slightly before the completion of a single revolution of the print drum 63, the inertia of the whole arrangement is such that some overshoot of the print drum assembly 60 and hence of the print drum shaft 64 past the "home" position may occur. There is therefore a need for a limited amount of backlash so as to permit the print drum assembly 60 to reverse a small extent so that the shutter bar 48 may slide into the slot 651 in order to lock the print drum assembly in its home position.
  • the print drum assembly 60 must be prevented from freely rotating in the reverse direction in order to prevent fraudulent interference with the postage meter.
  • each recess 612 runs a small distance in the circumferencial direction but, as it does so, the radial distance of its circumferential wall from the central axis 613 of the rear bearing 61 gradually decreases. This is most readily apparent in Figures 22, 22a and 22b.
  • a roller 614 is provided in each recess 612.
  • a clutch plate 90 is disposed between the rear bearing 61 and the drive gear 65.
  • This clutch plate has four generally circumferentially extending tabs 91 and four drive tabs 92 that extend generally perpendicularly to the plane of the rest of the clutch plate.
  • the circumferential tabs 91 all point in the forward direction of rotation of the print drum assembly 60.
  • Each one of the drive tabs 92 extends into a respective one of the recesses 612, behind the associated roller 614. As may be seen from Figures 22, 22a and 22b, each drive tab 92 is located in the deeper part of its recess 612.
  • the drive tabs 92 also serve to hold in place the rollers 614 to prevent them from being shaken loose by somebody trying to interfere with the postage meter.
  • the print drum 63 In addition to carrying the digit wheels 631 for printing postage value, the print drum 63 also carries a rotatable device 635 for printing a selectable one of a number of slogans on the mailpiece being franked (see Figure 5).
  • a Maltese Cross 632 is provided on the print drum 63 in order to rotate the multiple slogan device 635.
  • the Maltese Cross 632 has been rotated either by means of physically being directly rotated or by means of some extension knob directly mounted thereon.
  • the Maltese Cross 632 if turned directly would require the lifting up of a drum cover, such as drum cover 4 shown in Figure 1, in order to achieve access thereto.
  • a knob is provided on the Maltese Cross 632, it could in the prior art arrangements project out of the housing so as to dispense with the need of having to move the drum cover.
  • the disadvantage of having such a knob is that it is a moving part on the exterior of the housing and rotates every time the print drum assembly 60 is rotated when a mailpiece is franked.
  • a mechanism which can be activated from outside the housing of the postage meter but which does not rotate or otherwise move when the print drum assembly 60 is activated to frank the mailpiece.
  • a lever 633 is pivotably mounted on the base unit 40 by means of an adaptor 421 so as to be pivotable about a pivot 6331.
  • the lever 633 is pivoted through a limited rotational range by means of depressing the slidable knob 8 previously described in relation to Figure 1. Upon depressing the knob 8 downwards, the lever 633 is caused to rotate clockwise as viewed in Figure 23 to the dotted position shown in Figure 23a.
  • a pawl 634 which is able to rotate relative to the lever 633 only in a clockwise direction A, as viewed in Figure 23a.
  • the pawl 634 is prevented from rotating anti-clockwise relative to the lever 633 by means of an abutment 6332.
  • the pawl 634 moves up into engagement with the Maltese Cross 632 and causes the Maltese Cross to rotate anti-clock wise (arrow B) through 90° so as to change the slogan being printed.
  • the rotation of the Maltese Cross 632 with the print drum 63 merely causes the pawl 634 to rotate clockwise relative to the lever 633, thereby effecting a ratchet action.
  • This ratchet action ensures that an accidental act of keeping the knob 8 depressed does not jam the Maltese Cross 632 and prevent the print drum assembly 60 from rotating.

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Security & Cryptography (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Devices For Checking Fares Or Tickets At Control Points (AREA)
EP19910308288 1990-09-21 1991-09-11 Frankiermaschine Expired - Lifetime EP0476918B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9020634 1990-09-21
GB9020634A GB2248042B (en) 1990-09-21 1990-09-21 A postage meter

Publications (3)

Publication Number Publication Date
EP0476918A2 true EP0476918A2 (de) 1992-03-25
EP0476918A3 EP0476918A3 (en) 1992-07-15
EP0476918B1 EP0476918B1 (de) 1996-05-15

Family

ID=10682564

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19910308288 Expired - Lifetime EP0476918B1 (de) 1990-09-21 1991-09-11 Frankiermaschine

Country Status (5)

Country Link
EP (1) EP0476918B1 (de)
JP (1) JPH04261877A (de)
CA (1) CA2051932A1 (de)
DE (1) DE69119519T2 (de)
GB (1) GB2248042B (de)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2102346A (en) * 1981-05-22 1983-02-02 Pitney Bowes Inc Postage meter value selecting system
US4398458A (en) * 1981-03-23 1983-08-16 Francotyp Gesellschaft Mbh Adjustment device for postage metering and value stamping machines
EP0177050A2 (de) * 1984-10-04 1986-04-09 Pitney Bowes Inc. Frankiermaschine mit drehender Wertwählervorrichtung
EP0177049A2 (de) * 1984-10-04 1986-04-09 Pitney Bowes Inc. Frankiermaschinen mit einer mit einem Schneckengetriebe ausgerüsteten Zahnstangenbewegungsanordnung
GB2166389A (en) * 1984-10-04 1986-05-08 Pitney Bowes Inc Electronic postage meter print wheel setting optimization system

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2177656B (en) * 1985-07-04 1989-04-05 Roneo Alcatel Ltd Value selection mechanism for postal franking machines
FR2665782B1 (fr) * 1990-08-07 1993-06-11 Alcatel Satmam Dispositif de reglage de molettes d'impression dans un machine a affranchir.

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4398458A (en) * 1981-03-23 1983-08-16 Francotyp Gesellschaft Mbh Adjustment device for postage metering and value stamping machines
GB2102346A (en) * 1981-05-22 1983-02-02 Pitney Bowes Inc Postage meter value selecting system
EP0177050A2 (de) * 1984-10-04 1986-04-09 Pitney Bowes Inc. Frankiermaschine mit drehender Wertwählervorrichtung
EP0177049A2 (de) * 1984-10-04 1986-04-09 Pitney Bowes Inc. Frankiermaschinen mit einer mit einem Schneckengetriebe ausgerüsteten Zahnstangenbewegungsanordnung
GB2166389A (en) * 1984-10-04 1986-05-08 Pitney Bowes Inc Electronic postage meter print wheel setting optimization system

Also Published As

Publication number Publication date
DE69119519T2 (de) 1996-12-05
EP0476918B1 (de) 1996-05-15
DE69119519D1 (de) 1996-06-20
GB2248042A (en) 1992-03-25
CA2051932A1 (en) 1992-03-22
GB9020634D0 (en) 1990-10-31
EP0476918A3 (en) 1992-07-15
JPH04261877A (ja) 1992-09-17
GB2248042B (en) 1994-07-13

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