Abstract:
In one embodiment, a print bar includes: a substrate having a longer part and a shorter part extending along and parallel to the longer part such that each end of the longer part extends past each end of the shorter part; and multiple printhead dies on the longer part of the substrate. In another embodiment, a modular print bar includes a first module including multiple printhead dies joined together end to end and a second module including multiple printhead dies joined together end to end. The second module is lapped together end to end with the first module.

Description:
BACKGROUND 
     In some inkjet printers a media wide array of stationary printheads is used to print on media moving past the array. For wider media, greater than 12″ for example, individual printhead modules each holding several printhead dies are usually arranged in a staggered configuration in which adjacent modules are offset from one another in the direction the media moves past the printheads. Also, the individual printhead dies within each module usually are also arranged in a staggered, offset configuration, thus creating a compound stagger—die to die and module to module. Offset array configurations make overall printer space less efficient and they present significant difficulties coordinating ink drop placement between printhead dies and between printhead modules to minimize print defects inherent in the staggered configuration. 
    
    
     
       DRAWINGS 
         FIG. 1  is a block diagram illustrating one embodiment of an inkjet printer. 
         FIG. 2  is a bottom plan view illustrating a media wide modular print bar, such as might be used in the printer of  FIG. 1 , according to one embodiment of the disclosure. 
         FIGS. 3 and 4  are more detailed bottom plan views of adjoining printhead modules from the print bar of  FIG. 2 . 
         FIGS. 5 and 6  are more detailed views of one example embodiment of a joint between individual printhead dies in the module shown in  FIG. 3 . 
         FIGS. 7 and 8  are more detailed views of one example embodiment of the joints between individual printhead modules in the print bar of  FIG. 2 . 
         FIGS. 9 and 10  illustrate another example embodiment of the joints between individual printhead modules in a modular print bar. 
         FIGS. 11 and 12  illustrate another example embodiment of the joints between individual printhead modules in a modular print bar. 
         FIGS. 13 and 14  are top plan views of adjoining printhead modules illustrating one example embodiment for supplying ink to each module. 
         FIG. 15  is a detailed view of a portion of the printhead module shown in  FIG. 13 . 
         FIG. 16  is a side elevation view illustrating one example embodiment of a pressure regulator unit for supplying ink to a printhead module. 
     
    
    
     DESCRIPTION 
     Embodiments of the new print bar were developed in an effort to shrink the print zone in the media transport direction with a readily scalable printhead array that allows high quality printing across media widths of up to several meters. Embodiments are described with reference to inkjet printing. The embodiments shown in the figures and described below, however, are non-limiting examples. Other embodiments are possible and nothing in the following description should be construed to limit the scope of the disclosure, which is defined in the claims that follow this Description. 
     Although embodiments of the new print bar are not necessarily limited to dispensing ink or other liquids, and may be used for dispensing other fluids, inkjet printheads generally are not practical for dispensing fluids composed primarily of gas(es). Thus, “liquid” as used in this document means a fluid not composed primarily of a gas or gases. A “printhead” as used in this document refers to that part of an inkjet type drop dispensing structure or assembly that expels drops of liquid from one or more openings, typically an array of hundreds or thousands of tiny orifices. A “printhead” is not limited to printing with ink but also includes inkjet type dispensing of other liquids and/or for uses other than printing. “Media transport direction” means a direction parallel to the axis along which the print media would move past the printhead modules in a print bar if the print bar were installed in a printer. “Transverse direction” means a direction across the media transport direction. A transverse direction is not necessarily perpendicular to the media transport direction. 
       FIG. 1  is a block diagram illustrating an inkjet printer  10  that includes a print bar  12  spanning the width of a print media  14 . Printer  10  also includes regulator units  16  associated with print bar  12 , a media transport mechanism  18 , an ink supply  20 , and an electronic printer controller  22 . Print bar  12  in  FIG. 1  represents generally an array of modules each carrying one or more printhead dies and the associated mechanical and electrical components for ejecting drops of ink on to a sheet or continuous web of paper or other print media  14 . A typical thermal inkjet printhead die, for example, includes an orifice plate arrayed with ink ejection orifices and firing resistors formed on an integrated circuit chip positioned behind the ink ejection orifices. The printhead die(s) in each module are electrically connected to printer controller  22 , typically through a flexible circuit tape holding multiple electrical conductors (often called signal traces), and fluidically connected to ink supply  20  through regulator units  16 . In operation, printer controller  22  selectively energizes ink ejector elements in a printhead die, or group of printhead dies, in the appropriate sequence to eject ink on to media  14  in a pattern corresponding to the desired printed image. Controller  22  in  FIG. 1  represents generally the programming, processor(s) and associated memories, and the electronic circuitry and components needed to control the operative elements of a printer  10 . 
       FIG. 2  is a bottom plan view illustrating one embodiment of a media wide modular print bar  24 , such as might be used for print bar  12  in the printer of  FIG. 1 .  FIGS. 3 and 4  are more detailed plan views of adjoining printhead modules  26  and  28  in print bar  24 . Print bar  24  and modules  26 ,  28  in  FIGS. 2-4  are viewed looking into the exposed ink ejection orifices, typically the bottom of the print bar  24  when the print bar  24  is installed in a printer. 
     Referring to  FIGS. 2-4 , print bar  24  includes multiple individual printhead modules  26  and  28  joined end to end with one another. Each printhead module  26 ,  28  includes multiple individual printhead dies  30  and  32  joined end to end with one another on a substrate  33 . Printhead dies  30  and  32  are located on a longer part  34  of substrate  33  along the bottom  35  of each module  26 ,  28 . Electrical contacts  36  are located along the outboard side  38  ( FIGS. 5 and 6 ) of each die  30 ,  32  for connection to external circuits. Thus, power and other electrical conductors are routed to printhead dies  30 ,  32  over a longer edge  39  of substrate longer part  34  at the bottom  35  of each module  26 ,  28 , resulting in an alternating configuration of the flex circuits or other suitable cabling feature  40  ( FIG. 2 ) carrying power and other signal traces to modules  26  and  28 . As described in more detail below with reference to  FIGS. 13-16 , ink is routed to printhead dies  30 ,  32  through flow control, pressure regulator units or other suitable ink supply features  42  ( FIG. 2 ) over a shorter edge  43  of a substrate shorter part  44  along the top  45  ( FIGS. 13-16 ) of each module  26 ,  28 , resulting in an alternating configuration of ink supply units  42 . This alternating configuration allows cabling  40  to be routed straight into each module  26 ,  28  to help minimize the length and thus the electrical resistance of the signal traces. Where, as here, cabling  40  is routed over longer edges  39 , then the ink supply should be routed over shorter edges  43  in a similar alternating configuration if the ink is to be brought in from the sides of modules  26 ,  28 . 
       FIGS. 5 and 6  are detailed views of one example embodiment of the joints between individual printhead dies  30  in each module  26  and  28  shown in  FIGS. 2-4 . Due to the smaller scale of  FIGS. 2-5 , the array of ejector orifices is indicated generally by a centerline  46 . The details of one example embodiment for an orifice array  46  are shown in the larger scale of  FIG. 6  in which array  46  consists of four pairs  48  of rows  50  of orifices  52 —the orifices  52  in each pair of rows  50  may be used to eject a different color ink, cyan, magenta, yellow and black (CMYK) for example. Referring to  FIGS. 5 and 6 , orifice array  46  is offset in a triangular configuration  53  at one end  54  of each printhead die  30 ,  32  and both ends  54  and  56  of each die  30 ,  32  are sloped along triangular offset  53  such that orifice array  46  (and orifices  52 ) overlap at the joint  58  between dies  30  and  32 . Although a triangular offset configuration is shown, other suitable overlapping arrangements may be used. While this overlap arrangement makes it easier to minimize print defects at the joint between dies, this arrangement is not easily scaled up for use in media wide printing for wider print media. A single printhead die is currently limited to about 1″ in width due to structural and processing limitations of the silicon die material. In addition, the number of dies that can be mounted together in a single printhead module is limited by the capacity of the mounting substrate to hold the dies in a flat plane. As the width of the printhead module exceeds about 8″ (with 1″ individual printhead dies, for example), a “potato chip” effect is observed in which the printhead dies are no longer held uniformly in a flat plane. Thus, a new modular print bar has been developed to shrink the print zone in the media transport direction with a readily scalable printhead array for printing across wider print media. 
       FIGS. 7 and 8  are more detailed views of one example embodiment of the joints between individual printhead modules  26  and  28  in print bar  24  ( FIG. 2 ). Referring to  FIGS. 7 and 8 , the step  60  formed by the offset between longer and shorter parts  34  and  44  at the ends  62 ,  64  of each module  26 ,  28  fit together to form overlapping joints  66  ( FIG. 7) and 68  ( FIG. 8 ). This type of joint is commonly referred to as a lap joint. Thus, modules  26  and  28  are lapped together end to end at joints  66  and  68 . (Where, as here, the parts joined are in line with one another, the lap joint is sometimes referred to as a half lap or half lap splice.) 
     Referring now to  FIG. 7 , printhead dies  30  in modules  26  are oriented such that an offset die end  54  is adjacent to module right end  64  at joint  66 . Printhead dies  32  in modules  28  are oriented such that a non-offset die end  56  matching offset die end  54  in module  26  is adjacent to module left end  62  at joint  66 . Conversely, and referring to  FIG. 8 , printhead dies  32  in modules  26  are oriented such that a non-offset die end  56  is adjacent to module left end  62  at joint  68  and printhead dies  30  in modules  28  are oriented such that an offset die end  54  is adjacent to module right end  64   64  at joint  68 . In an alternative configuration shown in  FIGS. 9 and 10 , modules  26  and  28  are lapped together at joints  66  and  68  through a sloped transition  67  between longer part  34  and shorter part  44 . Thus, the orifice arrays  46  (and, therefore, orifices  52 ) in printhead modules  26  and  28  overlap at each lap joint  66  and  68 . In these configurations, orifice arrays  46  in modules  26  and  28  are minimally offset from one another in the media transport direction but otherwise form a substantially seamless orifice array  46  in the transverse direction from module to module to module, etc. 
     The use of a lap joint allows overlapping orifice arrays  46  at joints  66  and  68  without staggering printhead modules  26  and  28 , thus combining the benefits associated with overlapping orifices (ease in minimizing print defects along the joints) with the benefits of a linear array of printhead modules (space efficient and scalable). To accommodate lap joints  66  and  68 , the line of printhead dies  30 ,  32  in adjoining modules  26  and  28  is offset in the media transport direction. That is to say, the line of printhead dies in adjoining modules is staggered in the media transport direction. This offset/stagger, however, is on the order of the width of a printhead die which is much smaller than the stagger/offset in conventional media wide array of printhead modules. 
       FIGS. 11 and 12  illustrate another example embodiment of joints  66  and  68 . Referring to  FIG. 11 , printhead dies  30  are oriented such that an offset die end  54  is adjacent to the right end  64  in modules  26  and to the left end  62  of modules  28  at joint  66 . Referring to  FIG. 12 , printhead dies  30  are oriented such that a non-offset die end  56  is adjacent to the left end  62  of modules  26  and to the right end  64  of modules  28  at joint  68 . The configuration of dies  30  at joints  66  and  68  in  FIGS. 11 and 12  may be advantageous in some implementations because it allows for identical printhead dies  30  on each printhead module  26  and  28 . That is to say, the end printhead dies are the same as the other printhead dies on each module  26 ,  28  in the die configuration shown in  FIGS. 11 and 12 . In the die configuration of  FIGS. 7-10 , by contrast, each end die  32  is different from the other dies  30 . 
       FIGS. 13 and 14  are plan views of adjoining printhead modules  26  ( FIG. 13) and 28  ( FIG. 14 ) illustrating one example embodiment for supplying ink to modules  26  and  28  and distributing ink to each printhead die  30 ,  32 .  FIG. 15  is a detailed view of a portion of printhead module  26  shown in  FIG. 13 .  FIG. 16  is a side elevation view illustrating one example embodiment of a regulator unit  70 , such as might be used for regulator units  16  in  FIG. 1 . Referring to  FIGS. 13-16 , in the example embodiment shown, four regulator units  70  are operatively coupled to each printhead module  26 ,  28 . Each regulator unit  70  may be used to supply a different color ink, cyan, magenta, yellow and black (CMYK) for example. Referring specifically to  FIG. 16 , ink is pumped or otherwise delivered to each regulator unit  70  at an inlet  72 , from a remote ink supply  20  ( FIG. 1 ) for example. Each regulator unit  70  represents generally any suitable combination of elements for controlling the flow and regulating the pressure of ink supplied to printhead modules  26  and  28 . In a typical regulator unit  70 , for example, ink flows from inlet  72  through a flow control valve  74 , pressure regulator  76 , and filter  78  to an outlet  80 , and from outlet  80  to an inlet  82  to printhead module  26 . The components of regulator unit  70  may include conventional flow control, pressure regulator and filter components well known to those skilled in the art of inkjet printing. Although a separate pressure regulator unit  70  is shown for each of four different color inks, other configurations are possible. For example, a single, dual-chambered regulator unit  70  may be used to supply two different color inks to two module inlets  82 . 
     Referring again to  FIGS. 13-16 , ink is distributed from module inlets  82  to printhead dies  30 ,  32  in each module  26 ,  28  through a series of conduits  84  that span the length of dies  30 ,  32 . Using the example noted above, each conduit  84  carries a different color ink from the corresponding pressure regulator unit  70  to printhead dies  30  and  32 . Other configurations are possible. For example, more than four conduits will be used if additional inks or other fluids are desired. Openings (not shown) along the bottom of each conduit  84  allow ink to flow into the slots in each printhead die  30 ,  32  that feed the expulsion chambers (not shown) for individual orifices  52  ( FIG. 6 ). For the orifice array  46  shown in  FIG. 6 , each conduit  84  would supply a different color ink to each pair  48  of rows  50  of orifices  52  (through the corresponding feed slots and firing chambers in printhead dies  30 ,  32 ). In the embodiment shown in  FIGS. 13-16 , ink is routed to each inlet  72  over the shorter edge  43  of module shorter part  44 . This configuration facilitates the adaptation of a conventional pressure regulator unit for use as unit  70  and helps provide clearance for ink supply lines (not shown) into inlets  72 . 
     The present disclosure has been shown and described with reference to the foregoing exemplary embodiments. It is to be understood, however, that other forms, details and embodiments may be made without departing from the spirit and scope of the disclosure which is defined in the following claims.