Abstract:
In one example, a structure to hold a printhead includes a surface defining an opening through which the printhead orifices may be exposed for printing and a replaceable shield shielding an area of the surface around the opening.

Description:
BACKGROUND 
       [0001]    Inkjet printers utilize printheads that include many tiny orifices through which ink is dispensed on to paper or other print substrate. It is desirable for many inkjet printhead assemblies to wipe the surface of each printhead surrounding the dispensing orifices periodically to remove ink residue that may interfere with good quality printing. 
     
    
     
       DRAWINGS 
         [0002]      FIG. 1  is a block diagram illustrating an inkjet printer with a printhead carriage implementing one example of a replaceable printing fluid shield. 
           [0003]      FIGS. 2 and 3  are perspective bottom and top views, respectively, illustrating a printhead carriage implementing one example of a replaceable printing fluid shield such as might be used in the printer shown in  FIG. 1 . 
           [0004]      FIG. 4  is the perspective view of  FIG. 2  with the printing fluid shield exploded away from the body of the carriage. 
           [0005]      FIGS. 5 and 6  are perspective views of the printing fluid shield in the carriage shown in  FIGS. 2-4 . 
           [0006]      FIG. 7  is a block diagram illustrating an inkjet printer with a print bar implementing another example of a replaceable printing fluid shield. 
           [0007]      FIGS. 8  is perspective view illustrating a print bar implementing one example of a replaceable printing fluid shield such as might be used in the printer shown in  FIG. 7 . 
           [0008]      FIG. 9  is the perspective view of  FIG. 8  with the printing fluid shield exploded away from the body of the print bar. 
       
    
    
       [0009]    The same part numbers designate the same or similar parts throughout the figures. 
       DESCRIPTION 
       [0010]    One undesirable effect of wiping the printheads in an inkjet printer to remove ink residue is the accumulation of ink residue on exposed surfaces around the printheads. In some conventional large format inkjet printers in which high volumes of ink are dispensed from printheads carried by a scanning carriage, a metal shield is permanently installed over the bottom of the carnage around the printheads to protect the carriage against corrosion from ink residue. After a large quantity of ink residue accumulates on the shield, some of the residue can be dislodged during printhead replacement or even during printing and fall on to the print substrate support platen or on to the print substrate. 
         [0011]    It has been discovered that new printhead cross-wiping techniques cause ink residue to accumulate on the bottom of the carriage and along the exposed sides of the printheads so that the carriage can no longer survive to its normal end-of-life service replacement. To help resolve this problem, a new, replaceable shield has been developed to protect the carriage. The new shield is easily removed from the carriage assembly and can be replaced before a potentially damaging quantity of ink residue accumulates on the shield, thus regenerating the surfaces around the printheads to minimize the risk of ink residue reaching the print substrate or the platen throughout the normal useful life of the carriage. 
         [0012]    The examples shown in the figures and described herein illustrate but do not limit the invention, which is defined in the Claims following this Description. 
         [0013]    As used in this document, a “printhead” means that part of an inkjet printer or other inlet type dispenser that dispenses fluid, for example as drops or streams. A “printhead” is not limited to printing with ink but also includes inkjet type dispensing of other fluid and/or for uses other than printing. 
         [0014]      FIG. 1  is a block diagram illustrating an inkjet printer  10  with a printhead carriage  12  implementing one example of a replaceable printing fluid shield  14 .  FIGS. 2-6  illustrate a printhead carriage  12  implementing one example of a replaceable shield  14  such as might be used in the printer  10  shown in  FIG. 1 . Referring first to  FIG. 1 , printer  10  includes a carriage  12  carrying multiple ink pens  16 . Inkjet ink pens  16  are also commonly referred to as ink cartridges or print cartridges and may dispense ink and other printing fluids from a printhead or multiple printheads  18  contained within the pen. As described in detail below with reference to  FIGS. 2-6 , shield  14  covers the exposed bottom surface of carriage  12  in the areas surrounding the dispensing orifices of each pen  16  to collect ink residue that would otherwise accumulate on carriage  12 . Carriage  12  with pens  16  illustrates just one example of a printhead assembly implementing a replaceable shield  14 . Other types of printhead assemblies implementing a shield  14  are possible. For example, instead of ink pens  16  with integrated printheads  18  shown in  FIG. 1 , the printhead(s) could be mounted separately on carriage  12  with replaceable ink containers operatively connected to the carriage mounted printhead(s). 
         [0015]    A transport mechanism  20  advances paper or other print substrate  22  past carriage  12  and ink pens  16 . Pens  16  are connected to printing fluid supplies  24 . Although remote supplies  24  are shown, the printing fluids could be located on carriage  12  or contained within each pen  16 . A controller  26  is operatively connected to carriage  12 , printheads  18  and substrate transport  20 . Controller  26  represents generally the programming, processor(s) and associated memory(ies), and the electronic circuitry and components needed to control the operative elements of a printer  10 . Controller  26  controls the movement of carriage  12  and substrate transport  20 . Controller  28  is electrically connected to each printhead  18  to selectively energize fluid dispensing elements for dispensing ink or other printing fluid in the desired pattern on to substrate  22 . 
         [0016]    Referring now to  FIGS. 2-6 , carriage  12  includes receptacles  28  to hold removable ink pens  16 . For a scanning carriage  12 , ink or other printing fluids are supplied to pens  16 , for example, through flexible tubing  30  shown in  FIG. 2 . Printing fluid may be supplied to pens  16  through tubing  30  from a separate supply station while still allowing carriage  12  to scan back and forth across the print substrate. (According to the coordinate system shown in  FIGS. 2-4 , carriage  12  scans across the print substrate in the X direction, the print substrate moves in the Y direction, and pens  16  dispense fluid in the Z direction.) 
         [0017]    Fluid dispensing orifices  32  on each ink pen  16  are exposed through openings  33  along the bottom surface  34  of carriage  12 . In the example shown, orifices  32  are part of a printhead  18  located in a snout  36  of each pen  16  that protrudes through openings  33  in carnage bottom surface  34 . Shield  14  includes a cover part  35  with openings  37  corresponding to carriage openings  33  so that cover part  35  covers carriage bottom surface  34  in the areas surrounding pen snouts  36 . Although other configurations are possible, it is expected that shield cover part  35  usually will conform to the bottom surface  34  of carriage  12  which, in this example, is flat. Also, in this example, shield  14  includes collars  38  surrounding openings  37  and covering the sides of each pen snout  36 . As noted above, one adverse side-effect of the new cross-wiping technique is the accumulation of ink residue on the exposed sides of snout  36 . Collars  38  on shield  14  collect ink residue that would otherwise accumulate on the exposed sides of snout  36 . 
         [0018]    During servicing, ink residue is wiped from the exposed parts of each printhead  18  at orifices  32 . Ink residue can spatter onto shield  14  during wiping. As noted above, if a sufficient quantity of ink residue collects on shield  14 , some of the residue can be dislodged when a pen  16  is replaced, or even during printing, and fall on to the print substrate support platen or on to the print substrate. To help resolve this problem, shield  14  is attached to carnage  12  with a releasable fastener  40  so that the dirty shield can be easily removed from carriage  12  and replaced with a new or recycled (clean) shield before a potentially damaging quantity of ink residue accumulates on the shield, 
         [0019]    In the example shown in  FIGS. 2-6 , releasable fastener  40  is configured as a pair of magnets  42  on shield  14  and corresponding ferrites or other magnetic features  44  on carriage  12 . Magnets  42  may be positioned in pockets  46  in shield  14  so they are not exposed to ink residue that collects on shield  14 . The magnets  42  could be located on carriage  12  and the ferrites  44  located on shield  14 . Shield  14  may be aligned to carriage  12 , for example, with guide pins  48  protruding from carriage  12  and alignment holes  50  in shield  14  to receive guide pins  48 . In the example shown, one of two alignment holes  50  is significantly larger than the corresponding guide pin  48  to accommodate a misalignment tolerance between the parts. 
         [0020]    A magnetic or other such easy-release fastener  40  may be desirable in implementations in which shield  14  will be routinely replaced by the user rather than a service technician. However, other suitable releasable fasteners are possible, For examples screws may be desirable in implementations in which shield  14  will last until a routine printer service appointment when a service technician can replace shield  14 . 
         [0021]    A replaceable shield  14  need not be resistant to the corrosive effects of the ink residue that collects on shield  14 , at least not to the same degree as that needed for a permanent shield used in conventional printers. Thus, depending on the desired longevity of the shield and the operating environment (e.g. type of ink and temperatures) an inexpensive molded plastic shield  14  may be used. Suitable materials for a replaceable shield  14  include, for example, less expensive acrylonitrile butadiene styrene (ABS) where lower corrosion resistance is acceptable to more expensive polyphenylene oxide (PPO) where higher corrosion resistance is desired. 
         [0022]      FIG. 7  is a block diagram illustrating an inkjet printer  10  with a print bar  52  implementing another example of a replaceable printing fluid shield  14 .  FIGS. 8 and 9  illustrate a print bar  52  implementing one example of a replaceable shield  14  such as might be used in the printer  10  shown in  FIG. 7 . Referring first to  FIG. 7 , printer  10  includes a stationary print bar  52  for dispensing ink or other printing fluid on to substrate  22 . Print bar  52  includes multiple printheads  18  spanning the width of substrate  22 . For a substrate wide print bar  52 , printheads  18  usually will be connected to printing fluid supplies  24  through a set of flow regulators  54  that regulate the flow of ink or other printing fluid to corresponding printheads  18 . Referring now also to  FIGS. 8 and 9 , in this example, shield  14  is attached to the body  56  of print bar  52  with a releasable adhesive  58  that allows shield  14  to be easily removed from print bar  52  and replaced with a new or recycled (clean) shield before excess ink residue accumulates on the shield, Guide pins  48  protruding from print bar body  56  and alignment holes  50  in shield  14  may be used to properly alignment shield  14  to print bar body  56 . 
         [0023]    “A” and “an” used in the claims means one or more. 
         [0024]    As noted at the beginning of this Description, the examples shown in the figures and described above illustrate but do not limit the invention. Other examples are possible, Therefore, the foregoing description should not be construed to limit the scope of the invention, which is defined in the following claims.