Abstract:
A cartridge is provided with a supply housing having at least one exterior surface defining a supply area adapted to receive a donor ribbon of predetermined width and a take-up housing having a main wall that defines a take-up area for receiving donor ribbon of predetermined width. A take-up projection on the take-up housing and the main wall jointly define a take-up window therebetween through which donor ribbon passes into the take-up area. The take-up projection includes at least one tensioning feature so as to pre-load the take-up projection such that the take-up projection is inhibited from warping toward towards the main wall.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    Reference is made to commonly assigned, co-pending U.S. patent application Ser. No. 11/479,853, entitled UNIVERSAL DONOR CARTRIDGE filed Jul. 3, 2006 in the name of Lysiak et al. 
     
     FIELD OF THE INVENTION 
       [0002]    The invention relates to improvements in donor cartridges for use in thermal printers. 
       BACKGROUND OF THE INVENTION 
       [0003]    A thermal printer produces images on a receiver medium by transferring donor material from a donor ribbon to the receiver medium by selectively heating the donor ribbon while simultaneously pressuring the donor ribbon against the receiver medium. In this way, heated donor material transfers from the donor ribbon to the receiver medium to form an image while unheated donor material remains on the donor ribbon. Transfer may be by flow of melted donor material or by movement of sublimated donor material to the receiver medium. The donor ribbon and receiver medium are separated after transfer of the material to yield a receiver medium having a pattern of deposited donor material forming an image. 
         [0004]    Donor ribbon is typically connected between a supply spool, which initially carries a supply of unused donor ribbon, and a take-up spool upon which used donor ribbon is wound. In operation, the take-up spool is rotated to draw donor ribbon from the supply spool and across the print head for use in printing. Often the donor spool and take-up spool are joined together by a structural framework to form a thermal donor cartridge. This structural framework positions the supply spool and the take-up spool in a preferred geometric relationship to facilitate proper loading and can also be used to provide surfaces that enclose or otherwise protect the donor ribbon from damage due to incidental contact and from damage due to exposure to contaminants. Such a thermal donor cartridge is disclosed in commonly assigned, co-pending U.S. patent application Ser. No. 11/479,853 filed Jul. 3, 2006 in the name of Lysiak et al. 
         [0005]    The cartridge disclosed in the above-mentioned U.S. patent application provides a take-up window between a take-up projection and a main wall of a donor ribbon take-up housing. Because the take-up projection needs to be very thin to meet other design criteria, the take-up projection tends to warp. Sometimes, the direction of warp is towards the main wall of the donor ribbon take-up housing; closing down the take-up window. When this occurs, it creates a donor pinch point during printing. Any such pinch point on the take-up side of the cartridge would cause an unusual gradient in the web tension on the take-up side of the thermal head, tending to result in image artifacts and resulting in user dissatisfaction. 
         [0006]    Another potential problem associated with cartridges such as shown in the above-mentioned U.S. patent application pertains to the desire to produce a printer that does not cause unnecessary vibrations. Such vibrations can arise when a receiver material rubs across a lower portion of the take-up projection. The image receiver rubbing on the take-up projection during printing generates a particular vibration due to the flexibility of the guide rib. Such vibration would be considered to be objectionable to many users, and can impact printer performance. 
       SUMMARY OF THE INVENTION 
       [0007]    In one aspect, a cartridge is provided with a supply housing having at least one exterior surface defining a supply area adapted to receive a donor ribbon of predetermined width and a take-up housing having a main wall that defines a take-up area for receiving donor ribbon of predetermined width. A take-up projection on the take-up housing and the main wall jointly define a take-up window therebetween through which donor ribbon passes into the take-up area. The take-up projection includes at least one tensioning feature so as to pre-load the take-up projection such that the take-up projection is inhibited from warping towards the main wall. 
         [0008]    In another aspect, a cartridge is provided with a supply housing adapted to receive a donor ribbon of predetermined width and a take-up housing defining a take-up area. A connecting portion extends between the supply housing and the take-up housing to provide a printing path for the donor ribbon from the supply housing to the take-up area. A main wall and a take-up projection extend between the take-up housing and the connecting portion to define a take-up window therebetween through which the donor ribbon passes into the take-up area. The take-up projection includes at least one tensioning feature so as to pre-load the take-up projection to inhibit the take-up projection from warping toward towards the main wall. 
         [0009]    In one embodiment the tensioning feature is adapted to force the take-up projection into a preloaded position, partially in tension and partially in compression, such as to dampen vibration of the take-up projection. The take-up projection has two ends and extends in a direction transverse to the path, the take-up projection being longer than the width of received donor ribbon. The tensioning feature is positioned on the take-up projection between the lateral edges of received donor ribbon and the end of the take-up projection. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is a top view of one embodiment of a donor cartridge; 
           [0011]      FIG. 2  is a side section view of the cartridge of  FIG. 1 ; 
           [0012]      FIG. 3  is a drive end side view of the cartridge of  FIG. 1 ; 
           [0013]      FIG. 4  is a bottom perspective view of the cartridge of  FIG. 1 ; 
           [0014]      FIG. 5  is a top perspective view of a lower portion of a cartridge that does not include features of the present invention and that illustrates the problem overcome by the present invention; 
           [0015]      FIG. 6  is a side section view of the cartridge of  FIG. 5 ; 
           [0016]      FIG. 7  is an enlarged detail view of a portion of the cartridge of  FIG. 5 ; 
           [0017]      FIG. 8  is a top perspective view of a lower portion of the cartridge of  FIG. 1 ; 
           [0018]      FIG. 9  is a side section view of the cartridge of  FIG. 8 ; and 
           [0019]      FIG. 10  is an enlarged detail view of a portion of the cartridge of  FIG. 8 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0020]      FIGS. 1 ,  2  and  3  illustrate respectively a top, section and drive end side view of a thermal donor cartridge  20 . The thermal donor cartridge  20  has a supply housing  22  with a drive end  23  and a non-drive end  24 . Supply housing  22  is formed from an upper exterior surface  25  and a lower exterior surface  26  that define a supply area  28 . Bearing surfaces  30  and  32  are provided by supply housing  22  and are adapted to receive and position a supply spool  40  having a supply of donor ribbon  42  within supply area  28 . Donor ribbon  42  typically comprises a plurality of patches of different donor material arranged thereon in sets. Such donor materials can include dyes, colorants, inks or any other thermally transferable image forming materials as well as overcoat materials such as generally transparent protective overcoat materials. 
         [0021]    A supply projection  27  is connected to lower exterior surface  26  and extends away from lower exterior surface  26  to allow donor ribbon  42  to pass from supply area  28  to a supply waypoint  29 . As is illustrated in  FIG. 1 , supply-housing  22  provides a supply window  34  through which donor ribbon  42  passes from supply projection  27 . 
         [0022]    Thermal donor cartridge  20  also has a take-up housing  52  with a drive end  53  and a non-drive end  54 . Take-up housing  52  is shown having an upper exterior surface  55  and a lower exterior surface  56  that define a take-up area  58 . Bearing surfaces  60  and  62  are provided by take-up housing  52  and are adapted to receive a take-up spool  68  that is connected to donor ribbon  42 . 
         [0023]    A take-up projection  57  extends away from lower exterior surface  56  to allow donor ribbon  42  to pass from a take-up waypoint  59  to take-up area  58 . As is illustrated in  FIGS. 1 and 2 , take-up housing  52  provides a take-up window  64  through which donor ribbon  42  can be received from take-up projection  57  so that donor ribbon  42  can pass from take-up waypoint  59  into take-up area  58  and onto take-up spool  68 . 
         [0024]    Supply housing  22  and take-up housing  52  are joined to and are held apart by a connecting portion  70  to form a separation area  74  therebetween along a length of thermal donor cartridge  20 . Connecting portion  70  comprises a non-drive end linkage  71  linking non-drive end  24  of supply housing  22  to non-drive end  54  of take-up housing  52 , and a drive end linkage  80  linking drive end  23  of supply housing  22  to drive end  53  of take-up housing  52 . Non-drive end linkage  71  and drive end linkage  80  extend for a distance to define a lateral separation between supply housing  22  and take-up housing  52 . 
         [0025]    Access window  76  allows printing structures to contact donor ribbon  42  so that at least a portion of donor ribbon  42  positioned along printing path  78  can be used for printing without substantially removing donor ribbon  42  from thermal donor cartridge  20 . In practice this typically means that a thermal printhead (not shown) can be advanced against a top surface of donor ribbon  42  to drive donor ribbon  42  against a receiver medium (not shown) that is supported by a platen or such like supporting printing surface (not shown). 
         [0026]    Supply waypoint  29  takes the form of a surface, which can be a stationary surface such as an edge of supply main wall projection  101 , a bar (not shown) or a rotating surface such as a shaft (not shown) around which donor ribbon  42  turns to enter a printing path  78 . Printing path  78  extends from supply waypoint  29 , through access window  76  to take-up waypoint  59 . Donor ribbon  42  turns at take-up waypoint  59  for travel through take-up window  64  to take-up area  58 . Take-up waypoint  59  can be a stationary surface such as an edge of take-up projection  57 , a bar (not shown) or a rotating surface such as a shaft (not shown) around which donor ribbon  42  passes while exiting printing path  78 . 
         [0027]    In this way, thermal donor cartridge  20  provides a donor ribbon path that flows from supply housing  22 , along supply projection  27 , to supply waypoint  29  through access window  76  and along a printing path  78  to take-up waypoint  59 , along take-up projection  57  and into take-up housing  52 . Any of these structures can provide surfaces that contact donor ribbon  42  and that can be used as donor ribbon guides leading the donor ribbon  42  from supply housing  22  through supply side edge  90  of access window  76  to a take-up side edge  92  of access window  76  and to take-up housing  52 . Accordingly, such donor ribbon guides can comprise the donor path. 
         [0028]    Thermal donor cartridge  20  is formed by inserting supply spool  40  and take-up spool  68  into one of a lower housing  86  or an upper housing  88  and assembling the other of the lower housing  86  or upper housing  88  thereto. In the embodiment illustrated, non-drive end linkage  71  comprises an non-drive end linkage upper portion  72  provided by upper housing  88  and a non-drive end linkage lower portion  73  provided by lower housing  86 , while drive end linkage  80  comprises a drive end linkage upper portion  82  on upper housing and a drive end linkage lower portion  84  on lower housing  86 . 
         [0029]    It will be appreciated that in other embodiments of the present invention, supply-housing  22 , take-up housing  52 , and connecting portion  70  can be formed using more or different components and using different assembly techniques. 
         [0030]      FIG. 2  further illustrates geometric relationships between various dimensions of cartridge of  FIGS. 1 ,  2 , and  3 , that will be used in the following discussions of the design the parameters for the thermal donor cartridge  20 .  FIG. 2  shows a cross section view of thermal donor cartridge  20  taken along the line illustrated in  FIG. 1 . 
         [0031]    As can be seen in  FIG. 2 , thermal donor cartridge  20  has a spool separation distance A defined as a separation between a supply spool axis  94  defined by bearing surfaces  30  and  32  for supply spool  40  and a take-up spool axis  96  defined by bearing surfaces  60  and  62  for take-up spool  68 . Within the spool separation distance A is separation area  74  between supply housing  22  and take-up housing  52 . As noted above, separation area  74  extends along a horizontal length B between supply housing  22  and take-up housing  52 . 
         [0032]    Printing path  78  extends along a horizontal length K from supply waypoint  29  to take-up waypoint  59 . Access window  76  extends along a horizontal length C of thermal donor cartridge  20  from a supply side edge  90  to a take-up side edge  92  of access window  76 . 
         [0033]    As is also shown in  FIG. 2 , the arrangement of supply housing  22 , supply projection  27  and connecting portion  70  position supply waypoint  29  at a supply side waypoint offset D measured along a supply spool axis  94  to supply waypoint  29 , while lower exterior surface  26  of supply housing  22  is positioned at a supply housing offset E measured along supply spool axis  94 . As is shown in  FIG. 2 , supply side waypoint offset D is larger than supply housing offset E. This creates a supply side separation F. As will be discussed and illustrated in greater detail below, supply side separation F is intended to provide sufficient separation to allow a pinch roller to be positioned proximate to supply waypoint  29  so that thermal donor cartridge  20  can be used in thermal printers that utilize a dual pinch roller receiver system to move a receiver medium during printing. 
         [0034]    Similarly, the arrangement of take-up housing  52 , take-up projection  57 , and connecting portion  70  position take-up waypoint  59  at a take-up side waypoint offset G measured along a take-up spool axis  96  from take-up waypoint  59  to take-up spool axis  96 , while lower exterior surface  56  of take-up housing  52  is positioned at a take-up housing offset H measured along take-up spool axis  96 . As is shown in  FIG. 2 , take-up side waypoint offset G is larger than take-up housing offset H. This creates a take-up side separation J. As will be discussed and illustrated in greater detail below, take-up side separation J is intended to provide sufficient separation to allow a pinch roller to be positioned proximate to take-up waypoint  59  so that thermal donor cartridge  20  can be used in thermal printers that utilize a dual pinch roller receiver system to move a receiver medium during printing. 
         [0035]    As best seen in  FIG. 10 , take-up window  64  is defined between take-up projection  57  of the lower cartridge and a main wall  100  of the upper cartridge half. Referring for a moment to  FIG. 5 , which is included to illustrate a potential problem associated with cartridges similar to that of the present invention, a modified take-up projection  57   a  tends to warp due to its necessary thinness. Sometimes, modified take-up projection  57   a  tends to warp towards main wall  100  of the upper cartridge half. This is illustrated in  FIGS. 5 ,  6  and  7 . When this occurs, it creates a donor pinch point during printing. Any such pinch point on the take-up side of cartridge  20  would cause an unusual gradient in the web tension on the take-up side of the thermal head, tending to result in image artifacts and resulting in user dissatisfaction. 
         [0036]    Another potential problem associated with cartridges such as shown in  FIGS. 5 ,  6  and  7  pertains to the desire to produce a low vibration printer. As can be seen in  FIG. 3 , receiver material rubs across the lower portion of modified take-up projection  57   a . The image receiver rubbing on the modified take-up projection  57   a  during printing generates a particular vibration due to the flexibility the portion of modified take up projection  57   a . Such vibration could be considered to be objectionable and potentially create an objectionable acoustic noise. 
         [0037]    In order to overcome the potential problems of “donor pinch” and unnecessary vibration, one or more tensioning features are provided that preload take-up projection  57 . In one embodiment illustrated in  FIG. 8 , a pair of tensioning features  102  and  104  have been positioned towards the outermost ends of take-up projection  57  so as to be between the lateral edges of the donor and the ends of take-up projection  57 . As can be seen in  FIG. 8  and perhaps more clearly in  FIGS. 9 and 10  (particularly when compared to  FIGS. 5-7 , respectively), the tensioning features pre-load take-up projection  57  so that it does not warp toward towards main wall  100  of the upper cartridge half, eliminating the risk of creating a donor pinch point during printing. The tensioning features also force take-up projection  57  into a preloaded position, partially in tension and partially in compression, which tends to dampen the sounds created by vibration of the take-up projection  57 . 
         [0038]    The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention. 
       PARTS LIST 
       [0000]    
       
           20  cartridge 
           22  supply housing 
           23  drive end 
           24  non-drive end 
           25  upper exterior surface 
           26  lower exterior surface 
           27  supply projection 
           28  supply area 
           29  supply waypoint 
           30  bearing surface 
           32  bearing surface 
           34  supply window 
           40  supply spool 
           42  donor ribbon 
           52  take-up housing 
           53  drive end 
           54  non-drive end 
           55  upper exterior surface 
           56  lower exterior surface 
           57  take-up projection 
           57   a  modified take-up projection 
           58  take-up area 
           59  take-up waypoint 
           60  bearing surface 
           62  bearing surface 
           64  take-up window 
           68  take-up spool 
           70  connecting portion 
           71  non-drive end linkage 
           72  non-drive end linkage upper portion 
           73  non-drive end linkage lower portion 
           74  separation area 
           76  access window 
           78  printing path 
           80  drive end linkage 
           82  drive end linkage upper portion 
           84  drive end linkage lower portion 
           86  lower housing 
           88  upper housing 
           90  supply side edge of access window 
           92  take-up side edge of access window 
           94  supply spool axis 
           96  take-up spool axis 
           100  main wall 
           101  supply main wall 
           102  tensioning feature 
           104  tensioning feature 
         A spool separation distance 
         B separation area horizontal length 
         C horizontal length of access window 
         D supply side waypoint offset 
         E supply housing offset 
         F supply side separation 
         G take-up side waypoint offset 
         H take-up housing offset 
         J take-up side separation 
         K horizontal length between waypoints