Patent Publication Number: US-7216954-B2

Title: System for evaporating waste ink in a postage meter

Description:
BACKGROUND 
   This invention relates generally to the field of postage meters and is more particularly concerned with handling of waste ink in postage meters. 
   Postage meters that employ an ink jet printing unit are in widespread use. To maintain printing quality it may be necessary to purge dried or partially dried ink and/or air bubbles from the printing unit. For that reason, it is known to include an ink purge unit in a postage meter that employs ink jet printing. At selected times, the purge unit is engaged with the ink jet printing unit to remove waste ink from the ink jet printing unit. The waste ink is deposited in an absorbent pad. 
   In the United States, postal regulations require that postage meters be rented, not sold, to aid in maintaining the security of postal funds. It is not unusual for postage meters to come off rental after use by a postal patron for a period of time. The postage meters may then be returned to the manufacturer/owner of the meters for refurbishment, if needed. The returned meters may then be rented to other postal patrons. 
   During shipment or handling of postage meters to return the meters to the manufacturer/owner, it may occur that the meters may be tipped over, or carried on their sides or upside down. When this occurs, waste ink may drip out of the absorbent pad to foul parts of the postage meter. In some cases the damage to operating parts of the meter, or disfigurement of the appearance of the postage meter, may be so great that it is not cost effective to refurbish and re-rent the postage meter. In these cases the postage meter may need to be scrapped, leading to an increase in over-all cost to the meter manufacturer/owner. 
   SUMMARY 
   Accordingly, a system and method are provided to prevent fouling of postage meters from waste ink. 
   In one aspect, a postage meter includes a print head, a purge unit for removing ink from the print head, an ink tray for receiving ink removed from the print head by the purge unit, and a mechanism for heating the ink tray. 
   The mechanism for heating the ink tray may include a metal plate for supporting the ink tray and for conducting heat to the ink tray from at least one other component of the postage meter. The at least one other component may include at least one of a power supply and a motor. The metal plate may extend horizontally outwardly from a metal chassis that supports a power supply. The postage meter may include a pad held in the ink tray to absorb ink removed from the print head by the purge unit. 
   In another aspect, a postage meter includes a print head for printing a postage indicia on a mail piece, a metal chassis that includes a horizontal plate extending from the metal chassis, a transport unit for transporting the mail piece past the print head, a motor mounted on the metal chassis and coupled to the transport unit, a power supply mounted on the metal chassis for supplying power to the motor, a purge unit for removing ink from the print head, and an ink tray resting on the horizontal metal plate. The ink tray is for receiving ink removed from the print head by the purge unit. 
   In still another aspect, a method of operating a postage meter includes transporting ink from a print head to an ink tray, and heating the ink tray to promote evaporation of the ink in the ink tray. 
   The heating of the ink tray may include conducting heat to the ink tray from at least one of a power supply and a motor. The ink tray may be supported on a metal plate to which the heat is conducted from the at least one of a power supply and a motor. A metal chassis may conduct the heat to the metal plate from the at least one of a power supply and a motor. 
   By heating the waste ink tray, whether by use of waste heat from other meter components or by other means, evaporation of the waste ink in the tray may be promoted, so that the viscosity of the waste ink may be increased. Consequently, there may be an increased likelihood that the waste ink may be retained in an absorbent pad in the waste ink tray during shipment and handling of the postage meter. As a result, damage and/or befoulment of the meter by waste ink may be reduced or eliminated and the useful life of the meter may be extended. 
   Therefore, it should now be apparent that the invention substantially achieves all the above aspects and advantages. Additional aspects and advantages of the invention will be set forth in the description that follows, and in part will be obvious from the description, or may be learned by practice of the invention. Various features and embodiments are further described in the following figures, description and claims. 

   
     DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings illustrate presently preferred embodiments of the invention, and together with the general description given above and the detailed description given below, serve to explain the principles of the invention. As shown throughout the drawings, like reference numerals designate like or corresponding parts. 
       FIG. 1  is an isometric view of a postage meter in accordance with the invention. 
       FIG. 2  is a partially exploded view showing some of the internal components of the postage meter of  FIG. 1 . 
       FIG. 3  is an isometric view showing the interior of the postage meter of  FIG. 1 , with some of its internal components removed. 
       FIG. 4  is an exploded view of a waste ink tray assembly that is shown in  FIGS. 2 and 3 . 
   

   DETAILED DESCRIPTION 
   In the postage meter of the present invention, a waste ink tray is heated to promote evaporation of the ink held in the tray. The volume of the waste ink may thus be decreased, and the viscosity of the waste ink may be increased, making it substantially less likely that waste ink will be released from an absorbent pad in the waste ink tray during shipment and handling of the postage meter. 
   Referring now to the drawings, and particularly to  FIG. 1 , the reference numeral  10  generally indicates a postage meter provided in accordance with the invention. 
   The postage meter  10  includes a housing  12  formed of a lower case section  14  and an upper case section  16 . A slot  18  formed in the front  20  of the housing  12  allows a mail piece (not shown) to be transported through the postage meter  10 . The postage meter  10  also includes a transport unit  22  (partially visible through the slot  18 ) positioned at the slot  18  to transport the mail piece from an infeed side  24  of the slot  18  to an outfeed side  26  of the slot  18 . The postage meter  10  further includes a user interface  28  at the front  20  of the housing  12 , and a lever  30  positioned below the slot  18  to aid in clearing jams from the transport unit  22 . 
     FIG. 2  is a partially exploded view showing some of the internal components of the postage meter  10 . In addition to the above-mentioned transport unit  22  (which is more clearly visible in  FIG. 2 ), the postage meter  10  includes an ink jet print head  40 . In accordance with conventional practices, the transport unit  22  may operate to transport a mail piece (not shown) past the print head  40  so that the print head  40  may print a postage indicia on the mail piece. 
   The postage meter  10  also includes a waste ink purge unit  42 . At appropriate times, the purge unit  42  may come into engagement with the print head  40  to remove excess ink, dried or partially dried ink and/or air bubbles from the print head  40 . By a mechanism which is not shown, the print head  40  may be moveable in fore-and-aft directions between a print position adjacent the front of the meter  10  and a purge position that is aft of the print position. When in the print position, the print head  40  may operate to print postage indicia on mail pieces. When in the purge position, the print head  40  may be purged of waste ink by the purge unit  42 . 
   The postage meter  10  further includes a metal chassis  44 . The metal chassis  44  includes a vertical section  46  to which certain components (not shown in  FIG. 2 ) of the postage meter  10  may be mounted. The metal chassis  44  also includes a horizontal metal plate  48  which may be integrally formed with at least part of the vertical section  46  of the metal chassis. The metal plate  48  extends horizontally outwardly from the metal chassis  44  in a forward direction. 
   Also included in the postage meter  10  is a waste ink tray assembly  50 . When the postage meter  10  is in an assembled condition (not shown in  FIG. 2 ), the metal chassis  44  may rest on the bottom  52  of the lower case section  14  of the housing  12 , with the waste ink tray assembly  50  supported by and resting on the metal plate  48 . When the postage meter  10  is in its assembled condition, the waste ink tray assembly  50  is positioned below the purge unit  42  to receive from the purge unit  42  waste ink removed from the print head  40  by the purge unit  42 . 
     FIG. 3  is an isometric view showing the interior of the postage meter  10 , with some of its internal components removed. For example, the transport unit  22 , purge unit  42  and print head  40  shown in  FIG. 2  are omitted from  FIG. 3  to allow other components to be more readily seen. 
   As seen from  FIG. 3 , the postage meter  10  includes a motor  60  mounted on the vertical section  46  of the metal chassis  44  above the waste ink tray assembly  50 . A shaft and pulley arrangement, which is not shown, may be provided to couple the motor  60  to the transport unit  22  ( FIGS. 1 and 2 , not shown in  FIG. 3 ) to allow the motor  60  to drive the transport unit  22  so that the transport unit  22  may transport mail pieces through the slot  18  ( FIG. 1 ) and past the print head  40  ( FIG. 2 ). 
   The postage meter  10  also includes a power supply  62  mounted on the vertical section  46  of the metal chassis  44  to the right of the motor  60  and the waste ink tray assembly  50 . The power supply  62  supplies power to the motor  60  and to other components (not shown in  FIG. 3 ) of the postage meter  10 . For example, the power supply may supply power to the purge unit  42 . During operation of the postage meter  10 , the power supply  62  and/or the motor  60  may generate excess heat, which is conducted through the metal chassis  44  to the metal plate  48  ( FIG. 2 ) on which the waste ink tray assembly  50  rests. 
     FIG. 4  is an exploded view of the waste ink tray assembly  50 . As seen from  FIG. 4 , the assembly  50  includes an ink tray  70 , an absorbent pad  72  (which is held in the ink tray  70  when the assembly  50  is in an assembled condition) and a cover membrane  74 . The cover membrane  74  covers the pad  72  and substantially closes the ink tray  70  when the assembly  50  is in the assembled condition. As discussed in co-pending, commonly-assigned patent application Ser. No. 10/737,282, entitled, Ink Jet Printing System For Containment And Evaporation Of Waste Ink, hereby incorporated herein by reference, the cover membrane  74  may be such as to allow vapor to pass therethrough while substantially preventing passage of liquids. 
   In operation of the postage meter  10 , the power supply  62  is energized. Mail pieces are presented seriatim to the infeed side  24  of the slot  18  and are transported by the transport unit  22  (driven by motor  60 ) through the slot  18  past the print head  40 , which prints postage indicia on the mail pieces. The mail pieces are then ejected from the outfeed side  26  of the slot  18 . 
   On appropriate occasions, the print head  40  is moved from its print position (not shown) to its purge position (not shown), to allow the purge unit  42  to engage the print head. By action of one or both of the purge unit  42  and the print head  40 , excess ink, dried or partially dried ink and/or air bubbles are removed from the print head  40  by the purge unit  42 . The resulting waste ink is transported by the purge unit  42  to the waste ink tray assembly  50  and received by the pad  72  and the ink tray  70 . 
   The power supply  62  and/or the motor  60  generate excess heat, some of which is conducted by the metal chassis  44  to the metal plate  48  and the ink tray  70 . The heat conducted to the ink tray  70  by the metal plate  48  causes a modest increase in temperature in the waste ink tray assembly  50  and in the waste ink contained therein. The increase in temperature promotes evaporation of the waste ink. The evaporation of the waste ink reduces the volume of the waste ink, and increases the viscosity of the waste ink. 
   If it happens that the postage meter is handled or shipped after a period of usage, the decreased volume and increased viscosity of the waste ink in the waste ink tray assembly  50  may tend to prevent the waste ink from escaping from the waste ink tray assembly during shipment and handling. As a result, the postage meter may better tolerate shipment and handling, and may be substantially free of befoulment from waste ink. This may reduce or eliminate the need to refurbish the postage meter prior to re-renting and/or may make it unnecessary to scrap the postage meter due to such befoulment. Consequently, the postage meter may have an increased useful life or may have a lower operating cost and/or greater revenue-generating capacity over its total life cycle. In addition, with improved evaporation of waste ink, it may be feasible to reduce the size of the waste ink tray, thereby saving space in the housing of the postage meter. 
   In the embodiment illustrated herein, excess heat from the power supply and/or transport motor are conducted by a metal chassis, on which the power supply and motor are mounted, to the waste ink tray assembly via a metal plate extending from the chassis. In addition or alternatively, other mechanisms may be provided to heat the waste ink tray assembly, either with or without use of excess heat from operating components of the postage meter. For example, a thermally conductive foil strip or strips or a heat pipe may be provided to conduct excess heat from the power supply or motor to the waste ink tray assembly. In addition or alternatively, a separate source of heating such as a resistive electrical heating element may be provided adjacent to the waste ink tray assembly to heat the waste ink tray assembly. In other embodiments, the metal plate (if present) upon which the waste ink tray assembly rests may extend directly from the power supply rather than from a portion of the metal chassis that is apart from the power supply. 
   In some embodiments, the waste ink tray assembly may be modified by, for example, omitting the cover membrane. 
   The words “comprise,” “comprises,” “comprising,” “include,” “including,” and “includes” when used in this specification and in the following claims are intended to specify the presence of stated features, elements, integers, components, or steps, but they do not preclude the presence or addition of one or more other features, elements, integers, components, steps, or groups thereof. 
   A number of embodiments of the present invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the following claims.