CONTROL PANEL ARRANGEMENT FOR PRINTING SYSTEM

Abstract: A control panel arrangement for use in a printing system for applying indicia to a workpiece. The arrangement comprises (a) a control panel (6) which can be removed from the printing system (12) by an operator, the control panel (6) containing means (4) by which the operator can control the printing system; (b) control panel holding means (8) on the printing system adapted to hold the control panel (6) in at least two orientations relative to the printing system as selected by the operator; and (c) means (10) for operatively interconnecting the control panel (6) and the printing system (12).

Description: This invention relates to control panel arrangements for postage printing systems, for example to postage meters, and to printing systems having such arrangements. Reference is hereby made to other related copending European patent applications of even date in the name of the same applicant as the present invention: EP-A-0 121 799 corresponding to the U.S. application entitled "Postage printing Apparatus Having a Movable Print Head and a Variable Speed Drum Rotation", Serial No. 473 831, filed on 9th March 1983; and EP-A-0 118 906 corresponding to U.S. application entitled "Postage Printing Apparatus Having a Movable Print Head and a Rotating Print Drum and Ribbon Cartridge", Serial No. 473 418, filed on 9 March 1983. A removable print control panel in a franking machine is known from GB-A-1 508 623, for example. Postage meters for the application of indicia to a mailpiece are in general use today and thus are well known. The postage meter system prints pre-selected postage onto mailpieces or to adhesive-backed labels which are, in turn, applied to mailpieces. The operator pre-selects the value of the postage to be printed by punching it into a keyboad data entry unit in the system. In other systems the value of the postage may be automatically selected by scale and/or rate computer. Before using the meter the first time each day, the operator adjusts the date printed by the system to assure it conforms to the date the article is to be mailed. The day may also be automatically set by an associated digital clock. The value and date information is generally regarded as the variable data within the postage indicia to be imprinted on the mailpiece. In addition, fixed data may be and is generally used in the indicia. The fixed data may include the city and state of the originating mailpiece, the meter number, advertisements and other such information. In addition to postage meters, other types of imprinters may use a similar approach to printing control data in a manner similar to postage meters. These include parcel services, tax stamps, check writing services, and the like. Because some of the data placed in the indicia, such as the date and the value of the postage, must be variable, two printing sections for the indicia are generally combined by the postage meter to print the complete indicia, one section for the fixed data and one for the variable data. One such approach is to use a rotatable printing drum having die plates mounted on its periphery that are adapted to print fixed information. Also located on the periphery of the drum, in the vicinity of the die plates, are a group of settable print wheels which are adapted to print variable information such as the date and postage value. The settable print wheels project through suitable apertures formed in the curved surfaces of the print drum and rotate with the drum. When the drum is rotated or cycled, the die plates and print wheels are suitably inked so as to be capable of imprinting a composite indicia or marking of the fixed and variable data on a mailpiece. In order to vary or pre-set the postage value, a keyboard on the system is used to enter the value desired which automatically varies the operative positions of the print wheels to reflect the desired value. The linkage for setting and changing the print wheels requires an extremely intricate and mechanically complex arrangement. The print wheels are first set to selected rotary positions from the keyboard and then are bodily swung through a rotating printing path in conformance with the movement of the printing drum. The date is normally advanced each day by hand in this type of system. This system provides a way to print fixed and variable data at one printing station with one cycle of the drum. Another device that carries out the general function described above has the fixed information on a relatively flat die plate-like element with the variable information operably contained within the element. The variable data is implemented by settable print wheels which project through apertures in the die-like element. In this latter device, a mailpiece is placed under the element and a movable platform, which forms the bottom of the letter slot, drives the mailpiece up into the element after the latter has been set at the desired value and inked to create the indicia on the envelope. In a third type of known device, the print wheels and associated setting linkages described above and used for the variable data are dispensed with and replaced with an electronically controlled ink jet printing device. This type of apparatus is disclosed in U.S. Patent 3,869,986, assigned to Pitney Bowes, Inc., Stamford, Connecticut. In this device, the drum carries an apertured printing die plate which cooperates with a stationary ink jet printing device located in the drum to produce a composite postage imprint. One aperture is for the date and another for the postage amount. The die plate imprints the fixed data. As the apertures in the die plate pass below the ink jet printing device, a plurality of inked droplets are sequentially ejected ejected through the apertures and onto the mailpiece located at the meter print station. An electronic control is provided to actuate the ink jet printing device in timed relation to the movement of the die plate to form the required number and placement of ink drops on the envelope. This forms the variable data in the indicia; that is, the date and postage value. The device relies on a drum position sensor to determine when the die plate apertures are properly aligned with the ink jet printing device and the postage-receiving portion of the mailpiece. A print signal is generated by the sensor and applied to the electronic control to initiate a sequenced projection of the inked droplets. There has been a need for a compact, low cost and reliable postage meter. It is desirable to produce such a meter which does its printing at one print station so that registration problems are avoided. It is desirable to have the mailpiece compressed sufficiently as the indicia is being applied to it so that print quality standards are met in every cycle. The meter must also meet the usual standards of integrity and security. Although low cost, the meter design desirably should have a high rate of throughput in applying postage indicia for improved convenience and more efficient mail processing. According to one aspect of the invention, there is provided a control panel arrangement for use in a printing system for applying indicia to a workpiece, comprising: (a) a control panel which can be removed from the printing system by an operator, the control panel containing means by which the operator can control the printing system; (b) control panel holding means on the printing system adapted to hold the control panel in at least two orientations relative to the printing system as selected by the operator; and (c) means for operatively interconnecting the control panel and the printing system. According to another aspect of the invention, there is provided a printing system for applying indicia to a workpiece including said control panel arrangement. This invention is applicable to postage meter devices and methods for applying variable and fixed data in the form of indicia to a mailpiece. When so applied, the postage meter device has a rotary printing drum for applying the fixed portion of the data in the indicia and a print head located within the drum for applying the variable portion of the data in the indicia. The print head preferably has two positions, a printing position and non-printing position. The print drum preferably has an opening in its periphery through which the print head operates when in its printing position. The position of the print drum preferably determines when the fixed and variable data are applied to the mailpiece. The movement of the print head is preferably controlled so that it is enabled to assume its printing position when the aperture in the drum is between the mailpiece and the print head. In one embodiment of the invention as applied to a postage meter device, the print head, as it is carried within the drum, automatically is placed in its printing position by the internal configuration of the print drum acting on a print head positioning assembly. The print head reciprocates between its printing and non-printing positions and printing of the variable data is possible only when the head is in the printing position. The print head may be an impact matrix-type printer, the matrix being selectively activated to print depending upon the position of the print head on the mailpiece. The print head mechanism has a self-contained, automatic inked ribbon feeding and storage means which interacts with the print head to produce the variable indicia on the mailpiece. BRIEF DESCRIPTION OF THE DRAWINGS The objects and advantages of the control panel arrangement and postage printing device and method disclosed herein may be understood from the following description of the preferred embodiment as illustrated in connection with the drawings wherein: Figure 1 is a schematic illustration of the exterior of the postage meter with the mailpiece being loaded by an operator located at the side of the meter. Figure 2 is a schematic illustration of the exterior of the postage meter with the mailpiece being loaded by an operator located at the front of the meter. Figure 3 is a schematic illustration of the exterior of the postage meter with the control panel module disengaged from the body of the postage meter in preparation for being re-oriented relative to the body. Figure 4 is a schematic illustration of an indicia placed on a mailpiece by the meter. Figure 5 is a schematic illustration of the printing drum, mailpiece deck and impression roll, without the internal printing mechanism for printing variable data. Figure 6 diagrammatically illustrates a print drum with the internal impact matrix print mechanism looking into the front of the meter drum with the ribbon cartridge and covering components removed. Figure 7 diagrammatically illustrates the linkages of the print head positioning assembly. Figure 8 diagrammatically illustrates a top view of the print drum and print head assembly with the drum and immediate drum shaft area cut away to expose the print head assembly. Figure 9 diagrammatically illustrates the print drum and drum shaft area taken through section A-A of Figure 8, but without the drum being cut away. Figure 10 is a schematic illustration of the drive train for the print drum, exit roller and pivoting deck. Figure 11 is a cross-section view of the ribbon cartridge. Figure 12 is a cross-section view of the drum showing the print head assembly and ribbon cartridge feeding assembly. Figure 13 is a perspective view of the ribbon cartridge. Figure 14 is a view of the ribbon cartridge and postage meter as the operator prepares to install the cartridge into the meter. Figure 15 is a view similar to Figure 14 showing insertion of the cartridge into the meter. Figure 16 is a view of the cartridge after it has been placed in its installed position and the operator is about to lock the cartridge in place. Figure 17 is a view of the apparatus in Figure 12 taken through Section C-C with the cartridge of Figure 11 fully installed therein. Figure 18 is a view of the apparatus in Figure 12 taken through Section B-B. Figure 19 is a view of the cartridge in Figure 11 taken through Section A-A. Figures 20-26, section (a) only, are sequential views of Figure 17 at different points in the cycle of the print drum. Figures 20-26, section (b) only, are sequential views of Figure 18 at different points in the cycle of the print drum. Figures 20-26, section (c) only, are sequential views of Figure 19 at different points in the cycle of the print drum. Figure 27 is a timing diagram of the various components in the postage meter. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Except as otherwise provided herein, the instant postage meter apparatus may be constructed and arranged in a manner similar to that of presently known postage meters and associated apparatus. Therefore, the following description concentrates on those components of the postage meter and their operation which pertain to the invention. The remaining components of the postage meter system may be conventional and are described in a general manner to show the cooperation they have with the invention. A postage meter incorporating the present invention is an improvement over presently known postage meters such as models 5300 and 6300 postage meters manufactured by Pitney Bowes, Inc., Stamford, Connecticut. In addition to the printing module, postage meter systems include an information input module, such as a keyboard for entry of data into the meter and a display for exhibiting certain information in the meter, and a control module for controlling the operation of the system. U.S. Patent 3,978,457, assigned to Pitney-Bowes, discloses a postage meter system which uses a microcomputer set for a control module. U.S. Patent 3,978,457 is specifically incorporated by reference herein in its entirety. To the extent possible, like referenced numerals have been used throughout the drawings herein. It is to be understood that the following is a preferred embodiment of the invention. Although the invention is disclosed in the context of a postage meter, other types of devices may have the invention applied thereto with equal success and these include parcel service meters, tax stamp meters, check writing meters, and other similar devices. Figures 1 and 2 are external views of the low cost postage meter constructed in accordance with the invention. The postage meter has an external cabinet 2 with a control panel module 6 located in any convenient place on the cabinet such as on the top surface thereof. The control panel module 6 is understood to contain all of the features of a conventional postage meter including a keyboard 4 for entering the value of the postage and other data and a display 20 for displaying the value chosen and other data that is useful in the operation of the machine. In Figures 1B and 1C of US Patent 3,978,457 and the related descriptions, the various uses of the keyboard 4 and the display 20 have been shown and described. Figure 1 depicts the postage meter, supported by Table 1, receiving a mailpiece 14 which is loaded into mailpiece slot 12 by an operator located at the side of the machine. An arrow 16 shows the direction in which the mailpiece 14 is fed into the machine from a stack 15 of mailpieces to have postage indicia 30 (shown in Figure 4) applied thereto. Mailpieces are fed as shown in Figure 1 whenever convenient such as when there is a large stack of envelopes about the same size which are to have postage applied thereto. The operator can hold the stack in one hand and feed or "deal" each envelope one at a time into slot 12. The envelopes are fed out of the machine after postage is applied onto the Table 1 or into any suitable collection means. Figure 2 shows the postage meter being loaded with the mailpiece 14 by an operator located in front of the machine. This method of feeding mailpieces into slot 12 can be utilized whenever convenient for the operator such as when a single envelope is to have postage applied. The operator can stand in front of the machine and feed mailpiece 14 with his left hand into slot 12. After mailpiece 14 has had postage applied, the operator can conveniently catch the mailpiece (shown in dotted lines) with his left hand. In both Figures 1 and 2, the mailpiece 14 is slid into the mailpiece slot 12 in the direction shown by an arrow 16. Then, the mailpiece 14 is further fed in the direction shown by an arrow 22 by the printing mechanism to have the postage indicia 30 applied. According to one important feature of the apparatus in accordance with the invention, the mailpieces 14 may be loaded by an operator standing at the side or the front of the machine and still have the operator easily use the control panel module 6. As seen in Figure 3, the control panel module 6 may be lifted out of the rest of the cabinet 2 and orientated conveniently relative to the front of the machine or the side of the machine. The cabinet 2 contains a panel module holder 8 from which the control panel module 6 may be removed and replaced in a re-oriented position. The control panel module 6, in the embodiment shown, contains both the keyboard 4 and the display 20 as well as other devices related to the control of the machine. Since, in this embodiment, the control panel module 6 has equal-length sides, it may be readily slipped into the machine in a front or side orientation as desired by the operator. The control panel module 6 is joined to the control electronics of the postage meter by a control cable 10 continuously during the reorientation process. Figure 4 shows a sample mailpiece, or envelope 14, having the postage meter applied indicia 30 to create a meter stamp on the envelope. The indicia 30, in this embodiment, contains a postage value 32; a date 34 the stamp was made; city and state of origin 36; and an insignia with the postage meter number and country of origin 38. Two edges, 37, of the city and state of origin may be aligned with the two respective edges, 39, of insignia 38 for security purposes. If this is the case, the two lines, 40, printed as described hereinafter with date 34 and value 32 by a suitable print head, such as a matrix print head, can be utilized to detect fraudulently produced indicia. The print head actuation can be controlled precisely to align edges 40 with edges 37 and 39. If, upon visual inspection, these edges are not in alignment, the indicia can then be suspected as being a fraudulent one. The indicia 30 may further include advertising; not shown in Figure 4, alongside the indicia 30 shown, which may also be applied by the postage meter. The term "indicia" is used herein as a general term which is intended to mean the complete printing or print work that is applied by the postage meter onto the mailpiece 14. The portion of the indicia 30 in Figure 4, which relates to the value 32, and the date 34, is the variable portion of the indicia 30. In other words, it may be required to change this information quite often, even as frequently as each cycle of a print drum 50. The remaining portions of the indicia 30, such as the insignia 38, and the city and state 36, are representative of the fixed portions of the indicia 30. The variable portions of the indicia 30 may, in some respects, such as value, vary each time the postage meter makes a print cycle. On the other hand, the fixed portion of the indicia 30 basically remains the same for each print cycle made by the postage meter. The fixed portion, of course, may be changed, if desired, but is not intended to be changed frequently, and when it is changed, the change is generally made under security control. The variable portion of the indicia 30 must be made by a selectable or variable printing system. On the other hand, the fixed portion of the indicia 30 need not be carried out by a selectable printing system. However, in some embodiment, it may be desirable to have even the fixed portions of the indicia 30 printed by selectable printing processes. The postage meter disclosed herein enables the entire indicia 30, both the fixed and the variable portions, to be printed at one station during one cycle of the apparatus. The apparatus has a high mailpiece throughput rate. It is a feature of the postage meter, in accordance with the invention, to precisely match the positions of the fixed and variable portions of the indicia 30 relative to one another in a reliable manner. Referring particularly to Figures 5-8, a preferred embodiment of the postage meter print drum 50 has a variable indicia printing system, in this case an impact matrix print head 114, mounted within the rotating print drum 50 to print the entire indicia 30 in a single rotation of the drum 50. The non-rotating print head 114 prints through a slot 80 in the print drum 50 enabling substantially concurrent matrix printing of variable and fixed data. The print drum 50 is a one-piece molding and rotates about a fixed hollow shaft 122 which extends into the hollow interior of the drum 50. The print drum 50 has on its exterior a printing plate 54 which prints the fixed portion of the indicia 30 onto the mailpiece 14. The print drum 50 has a cam 76 on the interior thereof which controls the variable indicia print head 114 position. A cam 56 pitched to the rear of the drum 50 positions a pivoting mailpiece deck 62 and an impresssion roller 60. The pivoting mailpiece deck 62 and the impression roller mechanism 60 serve to movably support the mailpiece 14 during the printing process. The variable indicia printing system has a print head assembly 110, a print head positioning assembly 112 and a ribbon assembly 230. The print head assembly 114 is mounted within the interior of the print drum 50 on the end of the fixed shaft 122 by a linkage which enables a reciprocating motion of the print head 114 under the control of the cam 76 disposed along the inner face of the print drum 50. The motion, which basically allows a controlled rising and falling of the print head 114, is synchronized with the rotation of the slot 80 in the drum 50. The operative end of the print head 114 which carries out the variable printing process is placed in close proximity to the mailpiece 14 only during printing and then is withdrawn into the interior of the print drum 50 immediately thereafter. The ribbon system used with the matrix print head 114 is supplied in a user-replaceable cartridge 200 also mounted within the print drum 50. The cartridge 200, which rotates with the print drum 50, is arranged to stretch a chord 141 of inked ribbon 140 across the drum slot 80 under the print head 114. Rotation of the print drum 50 and ribbon system causes the rotating chord 141 to slide across the vertically descending tip of the print head 114 deflecting the chord 141 into the slot 80 during printing. The additional ribbon length required when the ribbon 140 is deflected from the chord 141 is delivered and taken up at constant tension by a spring-loaded idler roll means in the cartridge 200. In the preferred embodiment, a small percentage of the total length of ribbon 140 is circulated in and out of a ribbon storage container during each revolution of the print drum 50. The ribbon feed mechanism 230 is actuated mechanically during every cycle by the rotating motion of the print drum 50 and the cartridge 200 relative to the reciprocating print head 114. There is little relative sliding of the mailpiece 14 relative to the ribbon 140 and the print drum 50 during the printing operation. Ribbon feeding relative to its cartridge 200 is ordinarily restricted to periods when the print head 114 is not printing. Thus, in the illustrated embodiments, there is no special provision needed to prevent ribbon smear on the mailpiece 14. Figure 5 is a partial view of the postage meter apparatus which includes the print drum 50, the mailpiece deck 62 and the impression roller 60. For the purpose of simplicity, Figure 5 does not include the internal impact matrix printing mechanism 110 by which the variable data is printed. The print drum 50 has attached thereto printing dies, or printing plates 54, that print the fixed portion of the indicia 30. The drum 50 is mounted and journaled for rotation in the direction shown by the arrow by any suitable drive and control means. The drum 50 rotates in the counter clockwise direction bringing plates 54 past an inking roller 70. The roller 70 supplies ink to the plates 54 as they pass over it. Ink can be supplied to the roller 70 by the transfer rollers 72 and 74 which are coupled to any conventional ink supply (not shown). Alternatively, any conventional ink supply can be used to supply ink directly to roller 70 without the use of transfer rollers 72 and 74. The drum 50 and the inking roller system 70 are surrounded by a housing 52. The impression roll 60, which is carried by the mailpiece deck 62, is located under the drum 50. The mailpiece deck 62, impression roller 60 and the inking roller 70 form a printing station where the indicia 30 is placed on the mailpiece 14. The deck 62 pivots about a point 68 and carries a cam follower 59 which follows the cam 56 fixed to the rear of the drum 50 (also shown in Figure 10) due to the bias action of a spring 66. The deck 62 and its components, as well as any mailpiece 14 thereon, are biased toward the print drum 50. The distance from the drum 50 can be determined by the cooperating action of the cam 56 and the follower 59. The apparatus can also have an upstop member 63 which ultimately limits the pivoting of the deck 62, and impression roll 60 towards the drum 50. The deck mechanism 62 also includes an exit roller 64. When a mailpiece 14 is placed on the deck 62 and the deck 62 allowed to bring it up into contact with the drum 50 by the action of the cam 56 and the follower 59, the mailpiece 14 is gripped between the drum 50 and the cooperating impression roller 60, which is raised with the deck 62, so as to be longitudinally fed to the right across the deck 62. The printing plates 54, which are mounted on the drum 50 about the drum slot 80, are inked by the roller 70 and brought into contact with the mailpiece 14 to print the fixed portion of the indicia 30 on the mailpiece 14. As the slot 80 in the drum 50 passes adjacent the mailpiece 14, the variable indicia 30 are printed on the mailpiece 14 in a manner described below. A driven exit roll 64 further aids the movement of the mailpiece 14 to the right after printing contact with the drum 50 has been completed. The cam 56 fixed to the drum 50 is positioned relative to the slot 80 and the printing plates 54 on the drum 50 so that it allows the deck 62 and the impression roller 60 to squeeze the mailpiece 14 up against the drum 50 to remove air trapped within the mailpiece 14 for optimum print quality and then to place the postage indicia 30 on the intended area of the mailpiece 14. In the typical case when postage is placed on the upper right hand corner of an envelope 14, the envelope 14 would have its postage indicia 30 printed just after the leading edge of the envelope passed through the printing station. The slot 80 and a printing plate 54 on the drum 50 would be located to arrive at the station accordingly. After the plates 54 and the slot 80 have passed through the printing area, the cam 56 pushes the follower 58 away from the drum 50, thereby releasing the squeezing action on the mailpiece 14. The exit rollers 64 feed the mailpiece 14 out of the printing station and eventually out of the meter after the deck 62 has been lowered away from the drum 50. The deck 62 and the impression roller 60 are held away from the drum 50 by the control cam 56 to allow entry of the mailpiece 14. As the mailpiece 14 is placed into the mailpiece slot 12 and its leading edge brought into the vicinity of the impression roller 60, its leading edge contacts a lever (not shown) which can be moved a short distance by the mailpiece 14. The movement of the lever initiates rotation of the drum 50 and prevents further entry of the mailpiece 14. The trip lever assembly is conventional in postage meters and can be of the type used in the Pitney Bowes Model 6300 postage meter. It is connected by means of a linkage external to the deck 62 to its remotely-located control hardware. The leading edge margin can be adjusted by bending the trip lever to precisely locate the position of the mailpiece 14 when the drum 50 begins to rotate. After printing is completed, the cam 56 drives the cam follower 59 down, relaxing the grip that the impression roller 60 and the drum 50 had on the mailpiece 14. The system is designed so that the vertical motion of the deck 62 and the impression roller 60 are synchronized to rotation of the drum 50 without the use of expensive or mechanically complex hardware. This is accomplished by the cam 56 mounted on or formed integrally with the drum 50. The impression roller 60 is held depressed and clear of the drum 50 to allow easy entry of the mailpiece 14. Early rotation of the drum 50 allows a controlled rise of the spring-loaded deck 62 until the mailpiece 14 is squeezed between the rotating drum 50 and the impression roller 60. The height of the impression roller 60 may be adjusted by moving the bracket (not shown) on which it is mounted relative to the deck 62. The arrangement of the pivoting deck 62 and the impression roller 60, on the one hand, and the drum 50 on the other hand, provides rolling line contact on the mailpiece 14 during printing at a pressure approaching approximately 200 psi. This provides a most reliable means for handling and printing the different variations in stiffness, compressibility, air content and thickness that occurs when random pieces of mail are metered. This high pressure line of rolling contact enables the print head 114 for the variable indicia 30 to be reliably placed at an optimum distance from the mailpiece 14 without additional means. The impression roller 60 can be made of any suitable material. For instance, it may have a metal core that is rubber covered. It is mounted for rotation on a suitable bracket which is, in turn, attached to the pivoting deck 62 which is spring-loaded upward under the control of the cam 56 fixed to the rear of the drum 50. In some embodiments of the postage meter, space restrictions may require that printing be initiated as early as possible for maximum mailpiece throughput rate. These conditions would favor a configuration wherein the printing plates 54 on the drum 50 are inked after printing. There is a risk to print quality associated with this approach because of the ink drying on the plates 54 before the printing cycle has taken place, especially during lengthy periods between drum cycles. To correct this situation, control logic may be provided for a zero value cycle, that is, a nonprinting cycle to provide fresh ink on the plates 54 after an extended period of time has elapsed since the previous cycle. The print drum 50 may be manufactured in a completely round configuration without having a need for a flat section on its periphery and may be made of any suitable rigid material. A major cost reduction can be achieved over prior printing drums by employing unitary molding fabrication techniques such as die casting or injection molding techniques. These techniques allow the construction of the complex cam 76 inexpensively. This technique also significantly reduces required machining and assembly operations of the drum 50. The one-piece molded drum 50 is a highly cost effective component in view of the very large number of functions derived from its complex shape and its near freedom from the expense of the secondary machining and assembly labor which are characteristic of conventional drums 50. The printing plate 54 for fixed indicia or date 30 may be either integrally molded onto the drum 50 or attached to the drum 50 in the field after the machine is assembled. Suitable drum materials have been found to include either a 25% glass-filled acetal material or a 25% polycarbonate material. Both of these materials are sufficiently durable to withstand the normal repetitive stresses that the drum 50 would be exposed to in cycling. They have also been found to withstand the impact produced by depressing and releasing of the deck 62 as the drum 50 is rotated. To reduce impact loading, an adjustable deck up-stop can be used to limit compression of the rubber covered impression roll. Present commercial postage meters of this type use a rotating solid shaft connected to the print drum 50 to support and cycle the drum 50. The drum 50 shown herein uses a hollow non-rotating shaft 122 for supporting the drum 50. The shaft 122 and other related parts of the drum drive are best depicted in Figure 9 which is described below. The hollow shaft allows the electrical wires to be passed from the main control section of the meter, located outside the drum 50, to the printing head 114 located inside the drum 50. The hollow shaft 122 avoids the need to use commutation rings. Additionally, the non-rotating, hollowshaft 122 provides a convenient support for the printing head 114 inside the drum 50, optimum utilization of the interior cavity space, and a duct for bringing cooling air into the drum 50. The drum 50 also features a closed construction. The drum can provide good EMI shielding for the print head 114 and related circuitry, if desired, when made of a conductive material. The enclosed drum construction maintains a reduced level of dust in the area of the print head 114 and its linkage. The enclosed drum 50 also improves the physical security of the system and prevents tampering. Figures 6-10 are schematic illustrations of various aspects of the print drum 50 and the internal print head assembly 110 for printing variable indicia 30 located within and cooperating with the print drum 50. Referring, more particularly, to Figure 6, the print head assembly 110 is adapted to reciprocate relative to the drum 50. The assembly 110 moves down into the printing station only when the drum slot 80 is between the print head 114 and the mailpiece 14. Reciprocation of the print head assembly 110 is controlled by the angular position of the drum 50 and the action of the print head positioning assembly 112. The apparatus maintains a synchronous operation of the two printing systems; that is, the print head assembly 110 and the drum 50, to produce the indicia 30 on the mailpiece 14 during one cycle of the drum 50. The impact matrix print head 114 is lowered with its associated inked ribbon 140 through slot 80 in the drum 50 to print, by the impact of pins through the ribbon 140, variable information on the mailpiece 14. The printing plates 54, as they have rolling contact with the mailpiece 14, print the fixed information thereon. A portion of the interior surface of the drum can be used as a cam surface for the print head positioning assembly. The mailpiece 14 is brought into contact with the surface of the drum 50 and the printing plates 54 by the impression roller 60 being driven towards the mailpiece 14 and, in turn, driving the mailpiece 14 into the periphery of the drum 50. When the slot 80 is properly aligned between the print head assembly 110 and the mailpiece 14, variable printing can occur on the mailpiece 14 by virtue of the activating of the print head 114 against the ribbon 140. The ribbon 140 moves substantially at the same velocity and direction as the mailpiece 14 and the periphery of the drum 50 while the print head assembly 110 remains stationary during printing. Since the ribbon 140 moves at roughly the same speed as the mailpiece 14, smearing of the mailpiece 14 by the ribbon 140 is negligible. In addition, a different portion of the ribbon 140 is used to print a line of matrix print work during each cycle. The geometry of the system is such that the ribbon 140 is moved relative to the print head 114. The ribbon feeding control mechanism 230 operates in a manner such that the portions of the ribbon 140 on opposite sides of the impact matrix print head 114 are temporarily held or secured against movement during the printing operation. The ribbon 140 is advanced when it is out of engagement with the impact matrix print head assembly 110. This is more completely described hereinafter in conjunction with Figures 17 to 26. This arrangement avoids the necessity of driving the ribbon 140 and the drum 50 in synchronism which is a much more difficult condition to achieve in this type of environment. With the use of this system, the printing drum 50 can maintain a completely circular shape and the interior space of the drum 50 can be utilized more efficiently allowing a smaller print drum 50 to be used. Figure 6 is a diagrammatic illustration of a front view of the print drum 50 with the print head assembly 110 looking from the mailpiece slot 12 end of the postage meter. The mechanism depicted is simplified to clearly show the relative components of the two printing mechanisms. The mailpiece 14 is brought between the print drum 50 and the impression roller 60. In this embodiment, the drum 50 rotates in a counter clockwise direction driving the mailpiece 14 to the right as it rotates in contact with the impression roller 60. As the mailpiece 14 is driven through the nip of the drum 50 and the roller 60, printing occurs on the mailpiece 14 by two printing mechanisms. The first mechanism for printing is one or more printing plates 54 located on the periphery or face of the drum 50 which prints the fixed data on the mailpiece 14. The second mechanism for printing is the print head assembly 110 within the drum 50. The drum 50 has the slot 80 through which the print head assembly 110 reciprocates, in this embodiment upwardly and downwardly, to apply the variable data to the mailpiece 14. The print head assembly 110 movement is controlled by the print head positioning assembly 112 in combination with the cam 76. The shape of the cam 76 controls the print head 114 so that it is lowered through the slot 80 and down to a position adjacent the mailpiece 14 for printing only when the slot 80 is located between the mailpiece 14 and the print head 114. The lowering of the print head 114 is controlled by the cam follower roll 58 which is attached to the print head positioning mechanism 112 and which follows the cam 76 as the drum 50 rotates. A spacer roll 116 drops down onto the inside surface of the drum 50 during printing to correctly space the print head 114 relative to the mailpiece 14. The spacer roll 116, although not essential, is preferable in that is allows the print head 114 to follow the exact shape of drum 50 even though the drum 50 may be slightly out of round. Thus, as the leading edge of the slot 80 comes to the position between the mailpiece 14 and the print head 114, cam 76 causes the print head assembly 110 to drop down through the slot 80 to its printing position. As the trailing edge of the slot 80 approaches the position between the mailpiece 14 and the print head 114, the cam 76 causes the print head assembly 110 to lift back up to its position completely internal to the drum 50 to its non-printing position. The print head 114 reciprocates or oscillates relative to the slot 80 and the drum 50 in this manner during each cycle of the drum 50. The ribbon 140 rotates with the drum 50 while the print head assembly 110 does not rotate. Because of this relative movement the print head assembly 110 contains a ribbon guide 108 which acts to guide a ribbon chord 141 around the print head assembly 110 as the drum 50 carries the ribbon 140 through a complete revolution. While the print head assembly 110 is in its printing position, tension is maintained on the ribbon chord 141 by the print head 114 being positioned through the drum slot 80. The impact matrix printing head assembly 110 is conventional and may be Printhead Model Number LRC P/N 10311-002 supplied by Eaton Corporation, Printer Products, Technical Research Park, Riverton, Wyoming 82501 or other apparatus. This print head 114 is of the dot matrix type (seven pins), which has a recommended driver circuit and standard connector for the pin assignments. The inked ribbon 140 used with the print head assembly 110 is also conventional and can be any compatible type. For instance, it can be a ribbon supplied by Curtis-Young Corporation, 2550 Haddonfield Road, Pennsauken, N.J. 08110 identified as "Nylon 44, Black, Medium #4" in 3/16 inch width. The impact matrix process requires a relatively solid printing surface to assure availability of maximum impact energy for transfer of ink from the ribbon 140 to the mailpiece 14. Precise location of the printing surface relative to the print head 114 is also important to accommodate the relatively short stroke of the print head pins. Both requirements, while readily met in commercial printers, require special consideration when the process is used on a mailpiece 14 in a postage meter. The mailpieces 14 introduced to the postage meter have wide variations in thicknesses, surface textures and sponginess due, in part, to air content. With impact matrix printing, the surface aspects are important because of the throw length limitation of the print pins. By controlling the width of the slot 80 to a minimum in the printing drum 50, it has been found that the quality of the printing can be precisely controlled. The rolling line contact of the print drum 50 compresses the mailpiece 14. By controlling the dimensions of the opening through which the impact matrix print head assembly 110 projects, the high pressure developed by the rolling line contact bridges the aperture by creating a rigid print surface on the mailpiece 14 for the impact matrix pins to strike. Typically the aperture should be in the order of approximately 3/16 of an inch width measured parallel to the axis of the drum 50 and approximately 1.7 inches to 2 inches in length. These dimensions are intended to accommodate the print head assembly 110 described above and will change if a print head 114 of different dimensions is used. The important aspect is that the slot 80 width be closely controlled for minimum width to obtain the bridging effect of the slot 80 to produce a rigid print surface for the pins and the ribbon 140. In this embodiment, the high pressure line of rolling contact approaches to within approximately 0.03 inches of the lines of matrix print work to provide a zone of solid compression of the mailpiece 14. The slot 80 as described, provides suitable compression more effectively than any other known means and with no additional components for this function. The chord 141 of inked ribbon 140, see Figure 6, is stretched under tension between tips 218, 220 of two ribbon cartridge arms 204, 206, which are shown in Figure 11 described below. The ribbon cartridge arm tips 218, 220 and the slot 80 are located approximately in the same plane. The print head assembly 110 has connected thereto two guide plates 148, shown in Figure 12, which keep the ribbon 140 over the pins of the print head assembly 110. The matrix printing is otherwise conventional except for higher then usual sliding contact pressure by the ribbon 140 over the tip of the print head assembly 110. Bulging of mail into the slot 80 is prevented by relative sizes of the slot and the print head assembly 110. Unusual lumps in mail, which may project into the slot 80, tend to force the print head assembly 110 upward against the linkage follower spring, reducing the possibility of damage from this cause. Figure 7 illustrates the linkages of the print head positioning mechanism 112 which are also located inside the drum 50. The print head assembly 110 has been omitted in Figure 7 from the illustration to more clearly show the action of the linkage. A linkage support plate 100 is attached to the nonrotating, hollow shaft 122 (shown in Figure 9) upon which the drum 50 is rotated. The support plate 100 has movably mounted thereon links 102, 104 and 106. The link 102 is mounted to the plate 100 for movement about a pivot 134. The link 106 is mounted on the plate 100 and pivots about a pin 107. The link 104 is joined to and moves relative to the links 102 and 106 through pivot points 136 and 138, respectively. The link 104, which is fastened to the print head assembly 110, carries the print head assembly 110 (shown in Figure 6) in such a manner as to reciprocate the print head 114 relative to the drum 50 in cooperating relationship with the drum slot 80. The movement of the link 104 positions the print head 114 in respective printing and non-printing positions. As the drum 50 turns, the cam 76, being either part of or a discrete element fixed to drum 50, rotates with it and controls the movement of the cam follower roll 58. The cam follower roll 58 is joined to or mounted on the link 106 so that the print head positioning mechanism or assembly 112, and the print head assembly 110 which is mounted on the link 104 (not shown in Figure 7) moves under the control of the follower roll 58 as it rotates with the drum 50. The print head positioning assembly 112 is biased in a direction which holds the print head assembly 110 totally within the drum 50. This is the function of a spring 126 which is attached to the pin 107. The spring 126 is engaged about a spring mount 128 which is attached to the linkage support plate 100 and a spring mount 130 which is mounted on the link 106. Thus, the action of the spring 126 is to bias the print positioning mechanism 112 and the print head 114 into the print position and assure that the cam follower 58 is always in contact with the inside of the drum 50 on the cam 76. The movement of the printing portion of print head 114 is represented symbolically in Figure 7 by the arrow 144. The print head 114, in moving from its non-printing position to its printing position, actually moves in a somewhat arcuate path rather than in a strictly linear fashion in this embodiment. The arcuate path is retraced as the print head 114 moves from its printing to non-printing position. The reason for not making the path linear is to slightly displace the print head 114 from a position directly over its printing position when it is in its nonprinting position. This displacement allows greater clearance for installation and removal of the ribbon cartridge 200 from the drum 50 as described in conjunction with Figures 14 and 16. Figure 8 is a top view of the print drum 50 and the print head assembly 110 with the drum 50 and the immediate portion of the drum shaft 122 area cut away to expose the print head assembly 110. The meter uses the fixed, hollow shaft 122 to support the rotating print drum 50. The print head positioning assembly 112 uses two cam followers 58, 116 for controlling the print head 114. Both of these are best seen in Figure 6. The follower roll 58 provides the basic reciprocation action to the print head 114. The follower 116, which is operative on the movement of the print head 114 when it is in or adjacent its printing position, is mounted directly on the print head bracket to provide precise positioning of the print head 114 just before, during and just after matrix printing. Transfer of control of the print head's exact position passes from the follower roll 58 to the follower 116 just before matrix printing begins. The print head 114 is maintained in the up or non-printing position by the follower roll 58 in cooperation with a dwell surface in the cam 76. As mentioned beforehand, the drum 50 and its internal mechanism is carried by the fixed, non-rotating shaft 122 which is, in turn, mounted on the postage meter frame (not shown). The drum 50 is adapted to rotate about the non-rotating shaft 122 through the use of any suitable means, such as a bearing 124. The linkage support plate 100 is also mounted on the non-rotating shaft 122. The drum 50 has the cam 76 located on its internal surface upon which the cam follower roll 58 travels. The cam follower roll 58 is joined to the link 106 through a pivot stud 132. The spring 126 is mounted on a pivot stud bracket 146, which is mounted on the link 106. The link 106 rotates relative to the pivot point 107. The print head assembly 110 has a bracket 120 and a ribbon guide 108 which are carried by the print head positioning assembly 112 by being fastened to the link 104. The print head 114, itself, which is not visible in this figure, acts through the slot 80 in the drum 50. The drum 50 rotates about the fixed shaft 122, being driven therearound by any suitable drive mechanism (not shown). The drive mechanism drives through a gear 78 which is attached to the drum 50. Located between the drum 50 and the gear 78 is the cam 56 which is adapted to control the operation of the pivoting deck 62 and the impression roller 60. Figure 9 is a view of the drum 50 and the drum shaft area taken through section A-A of Figure 8, but without the drum 50 being cut back as in Figure 8. This figure shows the respective positions of a bearing 124, the gear 78 and the cam 56. Any suitable drive train can be used to operate the drum 50 and the deck 62 as described. Figure 10 shows one such apparatus. As a mailpiece 14 is placed into the mail slot 12 of the postage meter, its edge actuates a conventional trip finger to close a switch and start the printing cycle. A suitable drive means, such as a conventional motor 161, drives a gear train 160 which, in turn, rotates the printing drum 50 (not shown in this figure) and the exit feed rollers 64. The motor turns a shaft 182 which successively drives gears 162, 164 and 166. The gear 166 engages the gear 78, which is fixed to the print drum 50 and turns the drum 50 in the counter clockwise direction. The rotation of the gear 78 rotates the cam 56, which is also part of the drum assembly. The cam 56 controls the pivoting action of the deck 62 causing the deck 62 to rise at a constant velocity until the mailpiece 14 is pinched between the impression roller 60 and a feed knurl 212 on the drum 50. The mailpiece 14 is fed through the printing sequence and the deck 62 is driven gently downward beginning near the trailing edge of the mailpiece 14. Both the impression roller 60 and the feed exit roll 64 are driven in this embodiment. The impression roller 60 is driven through the gear train containing gears 170-180. The impression roller 60 is mounted on the same shaft as the gear 180 and turns therewith. The exit roll 64 can be driven by any suitable means such as belts or gears (not shown) also driven by a gear 162. The surface speed of the impression roller 60 is directly synchronized to the drum 50 at all times. Pivoting of the deck 62 is restricted to periods when printing does not occur. The drive system described enables one input to enable a synchronized driving relationship between the drum 50 and the deck 62. Although the print drum 50 can be rotated at any suitable constant speed throughout its cycle, it may also be operated at variable speeds. For instance, the cycle of the drum 50 may incorporate a particular constant speed during that portion of its cycle during which matrix printing takes place and a much higher speed during other portions of its cycle. In this manner, throughput of the mailpiece 14 is increased without intolerable deterioration of the matrix print quality. Exit speed of the mailpiece from the meter after printing is completed is a function of the exit roller speed. The speed of the exit roller 64 can be any suitable speed such as a speed higher than the speed of drum 50. The electronic controls, the operator keyboard 4 and other aspects of a complete postage meter system and their interrelationships with the printing mechanism disclosed herein, are designed in a conventional fashion. For instance, these aspects of the postage meter system described in U.S. Patent 3,978,457 can be used with the printing system disclosed herein. U.S. Patent 3,978,457 relates to a computerized postage meter system utilizing letterpress printing wheels set by electronically controlled solenoids and a stepping motor to print the variable portion of the indicia 30. A computer receives inputs from the keyboard 4 and generates outputs, handled through shift registers and output ports to various parts of the system including the control signals to the solenoids and the stepping motor for setting the print wheels of the postage meter. The present printing system utilizes an impact matrix printer rather than settable print wheels to form the variable portion of the indicia 30. Similar to the description in conjunction with Figure 1a of U.S. 3,978,457, when appropriate postal data information is provided from the input means, such as the input keyboard 4, a suitable device for appropriately driving the impact matrix printer responds to an appropriate output from the postal meter control device such as a CPU. This enables the printing system to cycle and apply the variable and fixed data to the mailpiece 14. The portion of the postage printing system in Figure 1a of the above-referenced patent labeled "PP" is equivalent to the impact matrix print head 114 and its associated mechanism while the portion labeled "SP" can be any suitable device for driving the print head 114 in a manner to print the appropriate variable indicia 30. For instance, the portion labeled "SP" can include a buffer storage means which receives the variable data information from the CPU for the cycle and an impact matrix print head character generator means which controls the activation of the pins of the print head 114 to produce the variable data as the mailpiece 14 moves relative to the print head 114. The impact matrix print head 114 forms the variable indicia 30 by activating selected pins as the mailpiece 14 moves relative to it. The print head 114 in this case can be a column of pins, such as seven individually activatable pins. The area to be printed, in this type of print head 114, is composed of columns, each of which represents a portion of the indicia 30. A particular combination of the pins, controlled by the character generator, is activated when the print head 114 is in each column. The characters generated, in turn, are dependent on the information in the buffer storage as further determined by the CPU of the postage meter. There is also provided in the system a means for controlling the timing of the operation of the impact matrix print head 114. This can be accomplished in any suitable manner. For instance, stationary optical sensors can be placed to detect the passage of certain positions on the rotating drum 50, such as by the passage of lugs or other target means attached to the drum 50, to indicate that the print head 114 be turned on and off. Three such trigger lugs on the drum 50 and a photo-sensor may be used to actuate matrix printing sequences at start-of-print, start-date and end-of-print. A fourth lug may be provided to indicate home position and end of drum cycle. These can be adjustable, both individually and as a unit. In this manner, the variable information in the indicia 30 to be printed can be located in a precise position relative to predetermined position of the fixed indicia 30 formed by the dies on the drum 50. Thus, forgery is much more difficult. The concept of locating the print head assembly 110 in the print drum 50 has a major advantage over the dual station type postage meter system wherein the variable and fixed data are printed serially. In the dual station system, the mailpiece 14 must transit between the printers and the manner in which this is done is critical to the proper alignment of the variable and fixed information. In the present system, proper alignment and resulting synchronization is a manufacturing adjustment and not a field service adjustment. Thus, once the system is manufactured and assembled, no further adjustment of synchronization between the two types of printing processes is necessary to obtain proper registration. Figures 11 and 12 are illustrations of the cross-section of the ribbon cartridge 200 and the print drum 50 showing some of their respective internal mechanisms. Figure 13 is a perspective view of the cartridge 200 from a ribbon chord 141 side. The variable data is printed by the print head 114 working in combination with the inked ribbon 140 in the ribbon cartridge 200 to produce printing on the mailpiece 114 through the slot 80 in the drum 50. The ribbon cartridge 200 is adapted to be disposable. When the spent cartridge 200 is removed, another cartridge 200 with the new ribbon 140 is placed into the drum 50 by the operator. The ribbon 140 is automatically aligned to be fed next to the print head 114 when it is placed in the drum 50. The ribbon 140 is advanced a small amount during each cycle of the drum 50 by the ribbon cartridge feeding assembly 230. After the ribbon 140 has been completely used, an indicator light (not shown) may be displayed to signal to the operator that the cartridge 200 should be replaced. The drum 50 may be inhibited from making any further cycles and the meter from making any further indicia 30 on the mailpiece 14 until the cartridge 200 is replaced. The operator then removes the cartridge 200 and replaces it with a new one. Figures 14 - 16 demonstrate how the cartridge 200 is replaced by the operator. As shown in Figure 14, the operator grasps the cartridge 200 by his fingers and aligns the cartridge arms 204 and 206 and the ribbon chord 141 with a chord access opening 234. This opening 234 is in the ribbon feed assembly mounting plate 232 which is fastened to the drum 50. Referring to Figure 15, the operator then inserts the cartridge 200 into and through the mounting plate 232 until the main portion of the cartridge 200 seats itself adjacent the mounting plate 232 so that ratchet faces 256 and 258 are engaged. Then, referring to Figure 16, the operator flips a lock lever 252 to lock the cartridge 200 in place so that it cannot inadvertently be removed from the drum 50. The locking of the interlock device signals the postage meter in any suitable manner, such as through electromechanical means, that a new cartridge 200 has been placed in the drum 50 and that the meter is ready to again apply postage impressions. The locking device can be any suitable type which is able to lock the cartridge to the drum. Although the postage meter embodiment described herein has a cartridge locking device, this feature has been left out of the drawings other than figures 14 - 16 in the interest of keeping the drawings simple. The ribbon system for the stationary impact matrix print head 114 is mounted within the print drum 50 and rotates with the drum 50 during its cycle of operation. Referring to Figures 11 and 12 , it can be seen that the cartridge 200 in Figure 11 is aligned with the drum 50 in Figure 12 so that the two can slide together for installation of the disposable cartridge 200. The ribbon 140 is positioned within the drum 50 such that it engages the matrix print head 114 when the print head 114 is lowered through the print drum slot 80. In accordance with this arrangement, while the print drum 50 is rotated from its home position to the position wherein the print drum slot 80 is aligned with the impact matrix print head 114 over the mailpiece 14, the ribbon chord 141 does not move relative to the cartridge 200. This positions the chord 141 between the impact matrix print head 114 and the mailpiece 14 for printing. A ribbon feed system 230, as shown in Figure 12, rotates with the print drum 50 and is actuated by the reciprocating impact matrix print head assembly 110. This approach simplifies the ribbon feed drive mechanism 230 and avoids the necessity of coupling the mechanism to the stationary drum shaft 122. A mechanism located internal to the replaceable ribbon cartridge 200 provides the uniform ribbon tension during the rise and fall of the matrix print head 114. The cartridge 200 has a construction that includes the two arms 204, 206 which extend the ribbon 140 in the cartridge 200 from the body of the cartridge 200 and positions the ribbon 140 along the chord 141. It is noted that employment of the cartridge arms 204, 206 is such that the cartridge 200 permits the ribbon 140 to be extended out from the body of the cartridge 200. Figures 17 and 18 are views of the apparatus in Figure 12 taken through sections C-C and B-B, respectively. Figure 19 is a view of the cartridge 200 shown in Figure 11 taken through section A-A. These three figures shown the apparatus in its home position. Figure 17 shows the arms 204 and 206 of the cartridge 200 in the area of the print head 114. The ribbon 140 is formed into a chord 141 between these arms 204, 206. The chord 141 interacts with the print head 114 when the print head 114 is activated through the slot 80 of the drum 50. The combination of the ribbon chord 141 and the print head 114 acting through the slot 80, on the one hand, and fixed printing plates 54 on the surface of the drum 50, on the other hand, produce the postal indicia 30. The ribbon guide 108 guides the ribbon chord 141 around the non-rotating print head assembly 110 as the drum 50 rotates thereabout and carries the ribbon cartridge 200 with it. A ribbon feed follower roll 210 interacts with the ribbon feed cam surface 108 to return a short length of the ribbon 140 to the cartridge 200 from the chord 141. Figure 18 is a view of a portion of the components of the ribbon cartridge feeding assembly 230. The feeding assembly 230 includes the feeding assembly mounting plate 232 which is mounted into the recess 235 (see Figure 12) of the drum 50 in a permanent manner. The mounting plate 232 has the additional function of reinforcing the drum 50 and thus makes the use of a molded drum possible. In the preferred embodiment, the mounting plate 232 is manufactured of steel. The mounting plate 232 has the chord access opening 234 which is dimensioned to allow insertion of the cartridge 200 and thus to clear the chord 141 and the cartridge arms 204, 206 upon installation of the cartridge 200 into the drum 50. The mechanism also includes a ratchet 244. The position of the ratchet 244 is controlled by a spring-loaded feed pawl 242 mounted on a two-arm crank 236 and an anti-backup pawl 246. Figure 19 is a partial cross-section of the cartridge 200. The major portion of the length of ribbon 140 is contained within a ribbon storage cavity 214. However, the ribbon 140 is passed out of the storage cavity 214 past an exit spring 216 and the cartridge arm 206 to form the ribbon or chord 141 length. After the chord 141 length is formed, the ribbon 140 comes back towards the body of the cartridge 200, cartridge housing 202, via arm 204 around cylindrical guide 222 and guide roller 224. It then is driven by the knurled ribbon feed roll 212 past a spring-loaded shoe 250 and back into the storage cavity 214. With the exception of the cartridge arms 204 and 206, this mechanism is basically contained within the cartridge housing 202. The following pertains to the balance of forces on the ribbon 140 as it is fed in the cartridge 200. The ribbon cartridge 200 is installed with the chord 141 straight and under tension. The cartridge 200 orientation for proper installation can be indicated by a suitable symbol such as a decal on the cartridge 200 and/or the drum 50. A conventional knurled extension on the feed roll 212 can be used which extends through the cartridge 200 for manual tightening of the ribbon 140 if removal of undesirable slack in the chord 141 length is needed during installation. During installation, a dancer 226 may be bottomed or only slightly deflected as long as it is under tension so as to hold chord 141 straight and under tension. When inserted while the drum 50 is at the home position, which is intended, the chord 141 touches nothing within the drum 50. Rotation of the print drum 50 causes the print head 114 to descend into the drum slot 80 deflecting the ribbon 140 from its straight chord 141 length between tips 218 and 220 of the cartridge arms. In normal operation (after the first cycle), the beginning of descent pulls the ribbon 140 through the arm 204 depressing the dancer 226 against its spring. Ribbon 140 withdrawal from the arm 206 is prevented by a conventional leaf spring at the storage cavity 214 exit during this time. Ribbon 140 withdrawal from the storage cavity 214 entrance is prevented by the spring-loaded shoe 250 bearing on the locked feed roll 212. Continued descent of the print head 114 tip causes the dancer 226 to bottom, preventing further withdrawal of the ribbon 140 through the arm 204. This bottoming increases the ribbon 140 tension and causes withdrawal of a relatively small segment of the ribbon 140 from the storage cavity 214 through the arm 206. At the bottom of descent, continued drum 50 rotation causes no further withdrawal from either arm 204, 206. Constant tension is maintained by the dancer 226 during printing. While the two chord 141 portions on either side of print head 114 tip are constantly changing length during printing, there is no major relative movement between the ribbon 140 and the mailpiece 14. In addition, the length of the ribbon 140 between the cartridge arm tips 218 and 220 remains constant. After printing, ascent of the print head 114 allows the slack in the ribbon chord 141 to be taken up by the dancer 226 which rises to the highest permitted point of its travel. This action draws the excess ribbon 140 into the arm 204, thus returning the portion of the ribbon 140 between the tips of the arms 218, 220 to a straight chord 141 length. Simultaneously with the print head 114 ascent, a cam 208, mounted on the print head assembly 110, actuates the ribbon feed lever 238 against its spring 237. The lever 238 is held in a "cocked" position after completion of ascent by a dwell on the cam 208. After three quarters revolution of the drum 50, measured from its home position, the "cocked" lever 238 is released, driving the feed roll 212 within the cartridge 200 approximately 45 degrees. Rotation of the feed roll 212 drives a small segment of the ribbon 140 into the storage cavity 214 and depresses the dancer 226 somewhat in the process. Differential error between the ribbon 140 length withdrawn from the exit and entered at the feed roll 212 is noncumulative. An over-tightened chord 141 with the dancer 226 bottomed at the initial cartridge 200 installation, for example, causes an abnormally large withdrawal on the first cycle but returns the system to its normal condition at the bottom of descent. Excessive feed at entry causes correspondingly excessive depression of the dancer 226. This condition results in earlier bottoming during the print head 114 descent and increased withdrawal. The ribbon 140 is fed by ribbon feed lever spring 237 on ribbon feed lever 238. This spring is designed to reliably overcome the feed roll 212 torque due to the shoe 250 pressure and also provides the torque necessary to depress the dancer 226. The sequence of positions for the drum 50 and the cartridge 200 shown in Figures 17 - 26 depicts the basic concept and operating sequence of the ribbon feeding mechanism 230. The number of components shown in these figures is purposely minimal to simplify the understanding of the operation. The order of events is basically described as they happen, although some inconsequential liberties have been taken with relative timing between the components for purposes of description. Reference is made to the timing charts in Figure 27 for a more accurate operational timing of the various components. Each figure in the sequence of Figures 17 - 26 shows the relative position of the key components at a particular point during a single revolution cycle of the print drum 50. Figure 17 and the (a) section of Figures 20 - 26 depicts a section through the drum 50 showing the print head assembly 110, including the impact matrix print head 114, arranged to reciprocate on a somewhat curved or accurate path under control of the cam 76 (shown in Figure 6) during rotation of the drum 50. The print head 114 is mounted on the print head positioning assembly 112 (shown in Figures 6 and 7) which is mounted on the support plate 100 (shown in Figure 7). The plate 100 is fixed to the end of the non-rotating shaft 122 (shown in Figure 8) which serves as an axis of rotation for the drum 50. The slot 80 in the drum wall is located in the face of the drum 50. A chord 141 of the inked ribbon 140 for matrix printing is stretched under tension between the tips of the two ribbon cartridge arms 204 and 206. The ribbon chord 141, the print head 114 tip and the slot 80 are all located in the same plane. The rubber covered impression roller 60, which is mounted on the pivoting deck 62 (shown in Figure 5), is spring-loaded upward under control of the cam 56 (shown in Figure 5) which is fixed to the rear of the drum 50. The ribbon feed cam 208 is mounted on the print head bracket 262, reciprocates with the print assembly 110 and is positioned in the same plane as the ribbon feed follower roll 210. Figure 18 and the (b) sections of Figures 20 - 26 depict the ribbon feed mechanism 230 mounted on the feeding assembly mounting plate 232 which is located and fixed into the internal portion of the drum 50 in the recess 235 (shown in Figure 12). The ribbon feed follower roll 210, also shown in the (a) sections of Figures 20 - 26, is mounted behind the plate 232 on the two-arm crank 238 which is spring-loaded in a counterclockwise direction. The crank arm 238, attached to the crank 236 and pivoting with it, carries the spring-loaded feed pawl 242. The pawl 242 is arranged to drive the ratchet 244 one tooth at a time when the crank 236, which has been reciprocated against the loading of spring 237, is released at the appropriate time by the cam 208. This drives the ribbon feed roll 212 within the cartridge 200 approximately 45 degrees through the face-ratchet coupling surfaces 256 and 258 (shown in Figures 13,14 and 15) attached to the ratchet 244 and the feed roll 212. The feed mechanism 230 is arranged to drive the feed roll 212 intermittently counterclockwise each cycle made by the print drum 50. Clockwise rotation of the feed roll 212 is prevented at all times by the anti-backup pawl 246. Figure 19 and the (c) sections of Figures 20 - 26 depict the interior of the user-installable, disposable cartridge 200. The ribbon 140 stored in the storage cavity 214 is lead from the cavity 214 and pinched by a leaf-type exit spring 216. After passing the spring 216, it is partially folded over itself, at approximately a 90 degree angle, to change direction and pass from the body of the cartridge 200 rearward along the inside of the cartridge arm 206 to the arm tip 220 (seen in Figure 13). At the arm tip 220, the ribbon 140 is again partially folded over itself, at approximately a 90 degree angle, and directed into the configuration of chord length 141 (shown in Figures 11, 13 and 14). In a similar manner, the ribbon 140 is partially folded over itself, at approximately a 90 degree angle, at the left end of the chord 141 to be directed back to the body of the cartridge 200 along the inside of the arm 204 (see Figure 11). At the end of the arm 204, it is fed around the cylindrical guide 222 and over the guide roller 224. The guide roller 224 is carried on the dancer 226 which is pivotally supported on the mount 228 and spring-loaded in the clockwise direction. After passing the roller 224, the ribbon 140 is lead around the knurled feed roller 212 and is held in close contact with the feed roller 212 by the spring-loaded shoe 250 before re-entering the storage cavity 214. The dancer 226 functions as a tension lever maintaining tension on the ribbon 140 between the exit spring 216 and the feed roller 212 including the ribbon chord 141. The ribbon 140 is restrained from being withdrawn from the storage cavity 214 exit by the friction induced by the exit spring 216 and from being withdrawn from the storage cavity 214 entrance by the feed roller 212. The feed roller 212 is restrained from rotating backwards, or in the clockwise direction, by the action of the anti-backup pawl 246. Figures 20(a) - (c) show the relative positions of the components after the drum 50 has been driven approximately 55 degrees in a counterclockwise direction from its 0 degree or home position. Up to this point in the cycle, the relative positions of the reciprocating components within the drum 50 have not changed. The deck 62 has not moved from its home position (shown in Figure 5) and the mailpiece 14 has remained stationary against the trip lever. These elements are all maintained in their respective locations while the drum 50 rotates through the first 55 degrees of the cycle. An interlock system in the postage meter, depicted generally by the interlock 252 in Figures 15 and 16, assures that the disposable ribbon cartridge 200 may only be removed or installed by the user with the drum 50 at its home position. The access cover 24 can only be opened with the drum 50 in home position and the meter cannot be operated with the cover 24 open. Interlock means (not shown) prevents operation with no ribbon 140 whether or not the cover 24 is closed. The ribbon chord 141, stretched under tension between the tips 218 and 220 of the arms 204 and 206, respectively, is placed by the operator into the access opening 254 in the circular ribbon feed plate 232 with the arms 204 and 206 engaged in grooves (not shown) on the inside of the drum wall. The grooves enable the arms 204, 206 to function as drawer slides. When the cartridge 200 reaches the position of being fully entered into the drum 50, spring-loaded engagement of the face ratchets, 256 and 258 (shown in Figures 13, 14 and 15) takes place to couple the drive ratchet 244, located in the drum 50, to the feed roll 212, located in the cartridge 200. The ribbon chord 141 can be inserted into the drum 50 without touching any component during entrance into the drum 50. The cartridge 200 is locked to the ribbon feed mounting plate 232 and the drum 50 once fully entered. In this manner, the cartridge 200 is loaded into the drum 50 and the ribbon feed mechanism 230 and the cartridge 200 are able to rotate as one unit. As the leading edge of the mailpiece 14 enters the meter to have postage applied thereto, it contacts a conventional postage meter trip lever, as described earlier herein, which moves a short distance. This movement initiates rotation of the drum 50 and prevents further entry of the mailpiece 14. The spring-loaded impression roller 60 is held clear of the drum 50 by its control cam 56 (shown in Figure 5) to allow entry of the mailpiece 14. After approximately 50 degrees of rotation, as shown in Figure 20, the ribbon chord 141 has rotated into contact with the print head 114 tip which has, up to this point in the cycle, been at rest in its "up" or non-printing position. The print head 114 now begins its descent towards the slot 80 and the mailpiece 14. No events, as yet have taken place in the components shown in Figures 20(b) and 20(c). At approximately 67 degrees of rotation, shown in Figure 21, the print head 114 tip has partially descended, deflecting the ribbon chord 141 from its straight line orientation between the cartridge arm tips 218 on arm 204, and 220, on arm 206. This forces the dancer 226 downward into contact with the down-stop surface 260. With the lightly spring-loaded dancer 226 prevented from absorbing further ribbon 140 once it is stopped by the down-stop 260, tension in the chord 141 increases. The increased tension causes additional ribbon 140 to be with drawn from the storage cavity 214 through the exit spring 216 and arm 206 as descent of the print head 114 continues. With completion of descent at about 71 degrees, as shown in Figure 22, approximately ¼ inch of the ribbon 140 has been withdrawn from the storage cavity 214 and light tension is maintained on the ribbon 140 by the dancer 226. The print head 114 tip is now fixed in its lowermost position within the slot 80 in the drum 50. The ribbon 40 is restrained from side-slipping off the print head 114 tip by thin guide flanks, 148 (best shown in Figure 12), fastened to the flanks of the tip of the print head 114. As the print head 114 descends, the trip lever, which had been restraining the mailpiece 14, is unlatched at approximately 60 degrees and yields forward about its pivot within the deck 62 leaving the mailpiece 14 free to advance. Simultaneous with the descent of the print head 114, the spring-loaded deck 62 (shown in Figure 5), which is biased upwardly, is allowed to rise under control of its operating cam 56 until the rubber-covered impression roller 60 contacts the mailpiece 14. The mailpiece 14 is pinched against the rotating drum 50 and feed is thereby initiated to the mailpiece 14. The drum 50 continues to rotate with the print head 114 accurately fixed in its "down" or printing position by means of the follower roller 116 (see Figure 6) which rides on the inside surface of the drum 50. This arrangement fixes the print head 114 and its ribbon 140 adjacent the periphery, of the drum 50 which is in rolling contact with the mailpiece 14. As the drum 50 rotates, the leading edge of the fixed indicia printing plates 54, on the periphery of the printing drum 50, is brought into registered relationship with the impact or printing wires in the print head 114 tip which provide the variable information. It is possible to simultaneously initiate both printing processes at approximately 75½ degrees of the drum cycle. Both processes take place at the line of rolling contact between the drum 50 and the impression roller 60. The high pressure at the line of rolling contact is particularly suited to matrix printing on the mailpiece 14. The fixed indicia printing plate 54 on the periphery of the drum 50 may be inked just prior to printing by a conventional one-inch diameter ink inpregnated ink roller fixed to the frame of the meter in the lower left quadrant of the drum 50 (shown in Figure 5) . As mentioned earlier herein, inking may also occur just after printing when using the first cycle of the drum 50 as a dead cycle after a relatively long period of non-use. The ink roller 70 is positioned to just clear the outside diameter of the drum 50 and just contacts the surface of the fixed indicia printing plate 54 on the periphery of the drum 50 after a few degrees of rotation. During printing, the deflected ribbon chord 141 maintains a constant length of ribbon 140 between the cartridge arm tips 218 and 220 (Figure 11). This creates a condition for mechanically generating an ellipse at the intersection of the two ribbon segments leading from the arm tips 218 and 220 where the arm tips 218 and 220 are the focii. The geometry is configured to have that portion of the ellipse disposed over the printing arc be a very close approximation of the outside diameter of the drum 50. The arrangement provides for relatively little movement of the ribbon 140 relative to the mailpiece 14 which would tend to smudge the mailpiece 14. The impact matrix print head 114, which prints the variable data in this embodiment, is precisely synchronized to the fixed data printing plate 54 on the periphery of the printing drum 50 by means of adjustable timing lugs on the drum which are sensed by photo-electric means on the frame of the machine. Although adjustable timing lugs are used in this embodiment, it will be understood that other mechanical or electrical sensing means might also be used. At the completion of printing, the ribbon feed follower roll 210 has rotated into contact with the cam surface 208 attached to the print head mounting bracket 262. The rise of the print head 114, beginning at approximately 125½ degrees in the drum cycle, as shown in Figure 23, causes the cam 208 to engage the ribbon feed follower roll 210. This forces the ribbon feed arm to rotate clockwise against its spring-loading. This advances the feed pawl 242 one tooth on the ratchet 244. The ratchet 244, then, again remains fixed by the anti-backup pawl 246. Simultaneously, during the rise of the print head 114, the ribbon 140 is restored to a straight chord length 141 (such as shown in Figure 17), and the dancer 226 takes up the ribbon slack in the clockwise direction away from the downstop 260. With completion of the rise of the print head 114 at approximately 143 degrees of drum cycle, as shown in Figure 24, the print head 114 is maintained in its "up" position. The ribbon feed follower roll 210 has advanced past that portion of its activating cam surface 208 which provides a controlled advance of the crank arm 240 and enters a dwell period. During this period, the arm 240 is maintained in a "cocked" (or clockwise) position. The ribbon chord 141 has rotated tangent to the track of the ribbon guide 108. The ribbon guide 108 guides the ribbon 140 clear of the print head assembly 110 within the drum 50 as shown in Figures 25 and 26. This arrangement allows a more compact drum design by the simple provision of assuring clearance of the print head assembly 110 as the drum 50 completes its cycle. Continued rotation of the drum 50, which may include the printing of a fixed indicia advertisement after printing the variable information via the print head 114, causes the deck 62 (see Figure 5) to be driven downward by its control cam 56. This releases the feed action on the mailpiece 14 by the drum 50. The feeding of the mailpiece 14 is transferred to the set of conventional power-driven exit rollers 64. Release may occur at any point over the approximate range of 206 degrees to 263 degrees of the drum cycle, depending on the thickness of the mailpiece 14, as shown in Figure 25. Continuation of the drum 50 rotation allows the ribbon feed follower roll 210 to drop off the end of the dwell portion of the cam surface 208 at approximately 266 degrees, as shown in Figure 26. This "fires" the spring-loaded feed arm 210 to advance the ratchet 244 one tooth in the counterclockwise direction. This action drives the feed roller 212, in the cartridge 200, approximately 45 degrees to enter approximately ¼ inch length of ribbon 140 into the storage cavity 214. This also causes the dancer 226 to be pulled downward, in a counterclockwise direction, against its spring loading. Further rotation of the drum 50 produces no event of significance and all components maintain their relative positions as the drum 50 completes its cycle and returns to its home position ready for the next entry of a mailpiece 14. Reference is made to Figure 27 for an approximate timing of the activation of the various elements described above in conjunction with Figures 17-26 as well as their relationship to the position of the drum 50 during its cycle. One cycle is 360 degrees. More specifically, the upper curves A and B show the position of the impression roller 60 face relative to the face of the drum 50. Movement of the impression roller 60 is, of course, accomplished by movement of the mailpiece deck 62 on which the impression roller 60 is carried. The horizontal coordinate of the curves in Figure 27 is the degree of rotation of the drum 50 about its axis. The vertical coordinate of curves A and B is the vertical displacement of roll 60 and shows various amount of clearance, abuttment, or penetration between the face of the drum 50 and the impression roller 60. The curve A represents the relative position of the faces of the drum 50 and the impression roller 60 when no mailpiece 14 is disposed intermediate these faces. The up-stop, referred to above, limits the upward travel of the deck 62 thereby limiting the over travel of the impression roller 60 during impact compression of the rubber, such as the rubber covering, on roll 60, as shown at point "f". This limits impact forces on the drum 50 and, thus, enables the use of low cost, lower strength drum materials feasible in the apparatus. The curve B shows the relative positions of these faces when a mailpiece 14 is intermediate the faces. The apparatus will ordinarily be dimensioned for use with a mailpiece having a ¼ inch maximum thickness, after air is driven out of the mailpiece 14 by the compression of the impression roller 60 and the drum 50. The curve D shows the timing of the variable print indicia 36 during the rotational cycle of the drum 50. The curve E shows the radial position of the tip of the print head 114 relative to the face of the drum 50. It will be seen that the tip of the print head 114 is substantially flush with the face of the drum 50 during printing of the variable indicia 36. Maximum retraction is about 0.568 inches. In some forms of the invention the replaceable ribbon cartridge 200 may be mounted so as to remain stationary instead of rotating with the drum 50. The rotational speed of the drum may vary during a rotational cycle. The drive means to accomplish this may be electrical or, alternatively, may utilize a non-circular gear drive. For example, a stepping motor may be driven at one stepping rate in one quadrant and at a second stepping rate in all other quadrants. It should be understood that the foregoing description and timing is only illustrative of the invention. Alternatives and modifications in the structural and functional features and timing of the system can be devised by those skilled in the art within the scope of the appended claims.

Claims: A control panel arrangement for use in a printing system for applying indicia to a workpiece, comprising: (a) a control panel (6) which can be removed from the printing system (12) by an operator, the control panel (6) containing means (4) by which the operator can control the printing system; (b) control panel holding means (8) on the printing system adapted to hold the control panel (6) in at least two orientations relative to the printing system as selected by the operator; and (c) means (10) for operatively interconnecting the control panel (6) and the printing system (12). An arrangement according to claim 1 characterised in that the means for operatively interconnecting the control panel and the printing system includes an electrical cord means (10). An arrangement according to claim 1 or 2 characterised in that the printing system is a postage meter (12), the workpiece is a mailpiece (14) and the control panel (6) includes means (4) for the operator to select the value of postage to be metered onto the mailpiece. A printing system for applying indicia to a workpiece characterised by a control panel arrangement according to any one of the preceding claims. A printing system according to claim 4 characterised by: (a) a cyclically operating drum means (50) for feeding the workpiece (14) through the system, the periphery of the drum means having an aperture (80) therein; (b) means (60) for maintaining the workpiece against the drum means (50) as the workpiece is fed by the drum means; (c) means (78,160,161) to cycle the drum means; (d) print had means (114) located internal to the drum means having a printing position and non-printing position, the print head means (114) being automatically placed adjacent the workpiece (14) through said aperture (80) in the drum means (50) to its printing position, when the aperture (80) is between the print head means (114) and a workpiece (14); and (e) means (110,112) to activate the print head means (114) when it is in its printing position. A system according to claim 5 characterised in that the drum means (50) is arranged to control the automatic placement of the print head (114) in its printing position. A system according to claim 5 or 6 characterised in that the print head means (114) has means to select data printed thereby for each cycle of the drum means (50). A system according to any one of claims 5 to 7 characterised in that the print head means (114) is of the impact type. A system according to claim 8 characterised in that the print head means is an impact matrix print head (114) and includes a cooperating inked ribbon means (140) to print on the workpiece. A system according to any one of claims 4 to 9 characterised in that the drum means (50) is supported for rotation by a shaft means (122). A system according to claim 10 characterised in that the drum means (50) has a driven member (78) and the drum means is cycled about its shaft means (122) by a motor means (161) and drive means (160) which act through the driven member. A system according to any one of claims 4 to 11 characterised in that the print head means (114) is arranged to reciprocate between its non-printing and printing positions as the drum means (50) is cycled. A system according to claim 12 characterised in that the reciprocating movement of the print head means (114) is controlled by the drum means (50). A printing system according to claim 4 characterised by: (a) a cyclable drum means (50) for feeding the workpiece (14) through the system, the periphery of the drum means having an aperture (80) therein; (b) means (60) for maintaining the workpiece against the drum means (50) as the workpiece is fed thereby; (c) a print head means (114) located within the drum means (50) for printing indicia on the workpiece (14); (d) means (58,76,112) for reciprocating the print head means (114) between printing and non-printing positions, the printing position placing the operative portion of the print head means (114) through the aperture (80) in the drum means (50) adjacent the workpiece; and (e) control means (50) for inhibiting the print head means from reciprocating to its printing position unless the aperture (80) in the drum means is between the print head means (114) and mailpiece and for inhibiting printing by the print head means (114) unless the print head means is in its printing position. A system according to claim 14 characterised in that the drum means (50) is the control means for inhibiting the print head means from reciprocating to its printing position. A printing system according to claim 4 for printing indicia having variable and fixed data portions on a workpiece (14) during a single cycle of operation, comprising: (a) a cyclable drum means (50) for feeding the workpiece (14) through the apparatus, the periphery of the drum means having an aperture (80) therein and a printing means (54) for applying the fixed data to the workpiece; (b) means (60) for maintaining the workpiece (14) against the drum means (50) as the workpiece is fed by the drum means; (c) means (78,160,161) to cycle the drum means (50); (d) variable data print head means (114) located internal to the drum means (50) having a printing position and non-printing position, the print head means (114) being automatically placed adjacent the workpiece through the aperture (80) in the drum means (50) to its printing position, when the aperture (80) is between the print head means and workpiece; (e) means (58,76,112) to activate the print head means (114) when it is in its printing position; and (f) means for varying the data to be printed by the print head means (114) whilst the fixed data portions of the indicia are printed onto the workpiece during one cycle of the drum means. A system according to any one of claims 5 to 16 characterised in that the drum means includes peripherally disposed printing means (54). A system according to claim 17 characterised in that the drum means includes a drum having integrally molded cam means and printing means. A system according to claim 18 characterised in that the drum means includes a generally circular metallic reinforcing plate (232) which is generally coaxially disposed with respect to the drum. A printing system according to claim 4 characterised by: (a) a cyclably operable drum means (50) for feeding the workpiece through the system, the drum means including printing means (54); (b) means (78,160,161) to cycle the drum means (50) and activate the printing means; (c) means (60) for maintaining the workpiece (14) against the drum means (50) while the printing means (54) prints on the workpiece, the means (60) for maintaining being mounted adjacent the drum means (50); and (d) means for controlling the means (60) for maintaining including means (56,62) for pivoting the workpiece (14) against the printing means (54) while printing takes place and to hold the workpiece clear of the drum means (50) as the workpiece enters the system before printing takes place. A system according to claim 20 characterised in that the drum means (50) controls the means (60) for maintaining the workpiece against the drum means. A system according to claim 17 wherein the drum means is a one-piece member. A system according to claim 20 wherein the means for maintaining the workpiece against the drum means is a pivoting deck means (62) having a roller means (60) thereon to maintain the workpiece against the drum means and, further including, upstop means for the deck means for limiting the impact of the roller means against the drum means.

Inventors: CLARK, JOHN I.
Applicants: PITNEY BOWES, INC.
Application year: 1984
Main classification: G07B17
IPC codes: B41J32, B41J2, B41J13, B41J3, G07B17, B41J35