Abstract:
A printhead including one or more fluid vias in fluid communication with a fluid supply, each of the one or more fluid vias being associated with a first number of heating elements, the heating elements being divided into groups of a second number of heating elements so as to form a number of primitive groups, and an electrical interface having at least one shift register that receives primitive address data to allow for selective application of electrical signals to the heating elements so that fluid is ejected from the printhead in accordance with image data, the number of primitive groups being dependent on the print resolution of the printhead so that a number of bits required for the at least one shift register to address each heater is independent of the print resolution of the printhead.

Description:
FIELD 
       [0001]    The present invention relates generally to the design of micro-fluidic ejection chips, and in particular, to the systems and method for controlling micro-fluidic ejection chips. 
     
    
     RELATED APPLICATION 
       [0002]    This application is a continuation of and claims priority to U.S. patent application Ser. No. 14/472,307, entitled ADDRESS ARCHITECTURE FOR FLUID EJECTION CHIP, filed Aug. 28, 2014, and is related to U.S. patent application Ser. No. 14/472,297, entitled CHIP LAYOUT TO ENABLE MULTIPLE HEATER CHIP VERTICAL RESOLUTIONS, filed Aug. 28, 2014, the contents of which are incorporated herein by reference in their entirety. 
       BACKGROUND 
       [0003]    In typical inkjet heater chip designs one of the first variables to be fixed is the vertical resolution of drop placement. From this starting point other properties such as the heater addressing matrix, input data register length, chip clock speeds etc. can be defined. Using this method, chips with similar properties except for vertical resolution often have incompatible electrical interfaces which require a unique ASIC, driver card and carrier for each design. While this may provide a cost effective bill of materials for a specific design, the savings can be offset by increased development resources and time to market. Therefore, this design approach is best suited for high volume designs with long product life cycles. 
       SUMMARY OF THE INVENTION 
       [0004]    An object of the present invention is to provide an improved chip architecture that enables shorter development cycles and customized designs to fit individual customer needs. 
         [0005]    A printhead according to an exemplary embodiment of the present invention comprises: one or more fluid vias in fluid communication with a fluid supply, each of the one or more fluid vias being associated with a first number of heating elements, the heating elements being divided into groups of a second number of heating elements so as to form a number of primitive groups; and an electrical interface comprising at least one shift register that receives primitive address data to allow for selective application of electrical signals to the heating elements so that fluid is ejected from the printhead in accordance with image data, the number of primitive groups being dependent on the print resolution of the printhead so that a number of bits required for the at least one shift register to address each heater is independent of the print resolution of the printhead. 
         [0006]    An inkjet printer according to an exemplary embodiment of the present invention comprises: a housing; a carriage adapted to reciprocate along a shaft disposed within the housing; one or more printhead assemblies arranged on the carriage so that the one or more printhead assemblies eject ink onto a print medium as the carriage reciprocates along the shaft in accordance with a control mechanism, wherein at least one of the one or more printhead assemblies comprises: a printhead comprising: one or more ink vias in fluid communication with an ink supply, each of the one or more ink vias being associated with a first number of heating elements, the heating elements being divided into groups of a second number of heating elements so as to form a number of primitive groups; and an electrical interface comprising at least one shift register that receives primitive address data to allow for selective application of electrical signals to the heating elements so that ink is ejected from the printhead in accordance with image data, the number of primitive groups being dependent on the print resolution of the printhead so that a number of bits required for the at least one shift register to address each heater is independent of the print resolution of the printhead. 
         [0007]    In at least one exemplary embodiment, for each of the one or more fluid vias, the first number of heating elements are arranged in a first column on one side of the fluid via and in a second column on another side of the fluid via. 
         [0008]    In at least one exemplary embodiment, the number of primitive groups is calculated according to the following equation: (the first number of heating elements)/(the second number of heating elements). 
         [0009]    In at least one exemplary embodiment, the first number of heating elements is calculated according to the following equation: (resolution per via)(print swath), where units of print swath is inches. 
         [0010]    In at least one exemplary embodiment, the printhead has a print resolution of 1200 dpi and the number of primitive groups is 40. 
         [0011]    In at least one exemplary embodiment, the printhead has a print resolution of 600 dpi and the number of primitive groups is 20. 
         [0012]    In at least one exemplary embodiment, the printhead has a print resolution of 300 dpi and the number of primitive groups is 10. 
         [0013]    In at least one exemplary embodiment, the printhead has a print resolution of 300 dpi, 600 dpi or 1200 dpi and the number of bits is 40. 
         [0014]    In at least one exemplary embodiment, the second number of heating elements is 34. 
         [0015]    In at least one exemplary embodiment, the second number of heating elements is within a range of 8 to 40. 
         [0016]    Other features and advantages of embodiments of the invention will become readily apparent from the following detailed description, the accompanying drawings and the appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    The features and advantages of exemplary embodiments of the present invention will be more fully understood with reference to the following, detailed description when taken in conjunction with the accompanying figures, wherein: 
           [0018]      FIG. 1  is a perspective view of a conventional inkjet printhead; 
           [0019]      FIG. 2  is a perspective view of a conventional inkjet printer; 
           [0020]      FIG. 3  is a block diagram showing the layout of a printhead according to an exemplary embodiment of the present invention; 
           [0021]      FIG. 4  is a block diagram showing the layout of a printhead according to another exemplary embodiment of the present invention; 
           [0022]      FIG. 5  is a block diagram showing the layout of a printhead according to another exemplary embodiment of the present invention; 
           [0023]      FIG. 6  is a block diagram showing the layout of a printhead according to another exemplary embodiment of the present invention; and 
           [0024]      FIG. 7  is a block diagram showing the layout of a printhead according to another exemplary embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0025]    The headings used herein are for organizational purposes only and are not meant to be used to limit the scope of the description or the claims. As used throughout this application, the words “may” and “can” are used in a permissive sense (i.e., meaning having the potential to), rather than the mandatory sense (i.e., meaning must). Similarly, the words “include,” “including,” and “includes” mean including but not limited to. To facilitate understanding, like reference numerals have been used, where possible, to designate like elements common to the figures. 
         [0026]    The address architecture according to exemplary embodiments of the present invention enables the design of heater chips of differing resolutions which can be controlled using a common electrical interface. This allows for realization of multiple vertical drop resolutions from a common base chip design. The invention enables significant improvements over conventional inkjet heater chip designs. For example, a common electrical interface can be used between chips of different resolutions. This simplifies print engine development and also allows for more flexibility during manufacturing since a single base chip can be targeted to multiple resolutions as the business needs dictate. 
         [0027]    One aspect of such a design is that as the heater resolution changes, the data stream to address the heaters may also change. It is desirable to design a single print engine capable of driving heads of multiple resolutions without impacting the electrical interface. 
         [0028]    With reference to  FIG. 1 , an inkjet printhead of the present invention is shown generally as  10 . The printhead  10  has a housing  12  formed of any suitable material for holding ink. Its shape can vary and often depends upon the external device that carries or contains the printhead. The housing has at least one compartment  16  internal thereto for holding an initial or refillable supply of ink. In one embodiment, the compartment has a single chamber and holds a supply of black ink, photo ink, cyan ink, magenta ink or yellow ink. In other embodiments, the compartment has multiple chambers and contains three supplies of ink. Preferably, it includes cyan, magenta and yellow ink. In still other embodiments, the compartment contains plurals of black, photo, cyan, magenta or yellow ink. It will be appreciated, however, that while the compartment  16  is shown as locally integrated within a housing  12  of the printhead, it may alternatively connect to a remote source of ink and receive supply from a tube, for example. 
         [0029]    Adhered to one surface  18  of the housing  12  is a portion  19  of a flexible circuit, especially a tape automated bond (TAB) circuit  20 . The other portion  21  of the TAB circuit  20  is adhered to another surface  22  of the housing. In this embodiment, the two surfaces  18 ,  22  are perpendicularly arranged to one another about an edge  23  of the housing. 
         [0030]    The TAB circuit  20  supports a plurality of input/output (IO) connectors  24  thereon for electrically connecting a heater chip  25  to an external device, such as a printer, fax machine, copier, photo-printer, plotter, all-in-one, etc., during use. Pluralities of electrical conductors  26  exist on the TAB circuit  20  to electrically connect and short the I/O connectors  24  to the input terminals (bond pads  28 ) of the heater chip  25 . Those skilled in the art know various techniques for facilitating such connections. For simplicity,  FIG. 1  only shows eight I/O connectors  24 , eight electrical conductors  26  and eight bond pads  28  but present day printheads have much larger quantities and any number is equally embraced herein. Still further, those skilled in the art should appreciate that while such number of connectors, conductors and bond pads equal one another, actual printheads may have unequal numbers. 
         [0031]    The heater chip  25  contains a column  34  of a plurality of fluid firing elements that serve to eject ink from compartment  16  during use. The fluid firing elements may embody thermally resistive heater elements (heaters for short) formed as thin film layers on a silicon substrate or piezoelectric elements despite the thermal technology implication derived from the name heater chip. For simplicity, the pluralities of fluid firing elements in column  34  are shown adjacent an ink via  32  as a row of five dots but in practice may include several hundred or thousand fluid firing elements. As described below, vertically adjacent ones of the fluid firing elements may or may not have a lateral spacing gap or stagger there between. In general, the fluid firing elements have vertical pitch spacing comparable to the dots-per-inch resolution of an attendant printer. Some examples include spacing of 1/300th, 1/600th, 1/1200th, 1/2400th or other of an inch along the longitudinal extent of the via. To form the vias, many processes are known that cut or etch the via  32  through a thickness of the heater chip. Some of the more preferred processes include grit blasting or etching, such as wet, dry, reactive-ion-etching, deep reactive-ion-etching, or other. A nozzle plate (not shown) has orifices thereof aligned with each of the heaters to project the ink during use. The nozzle plate may be a thin film layer attached with an adhesive or epoxy. 
         [0032]    With reference to  FIG. 2 , an external device in the form of an inkjet printer for containing the printhead  10  is shown generally as  40 . The printer  40  includes a carriage  42  having a plurality of slots  44  for containing one or more printheads  10 . The carriage  42  reciprocates (in accordance with an output  59  of a controller  57 ) along a shaft  48  above a print zone  46  by a motive force supplied to a drive belt  50  as is well known in the art. The reciprocation of the carriage  42  occurs relative to a print medium, such as a sheet of paper  52  that advances in the printer  40  along a paper path from an input tray  54 , through the print zone  46 , to an output tray  56 . 
         [0033]    While in the print zone, the carriage  42  reciprocates in the Reciprocating Direction generally perpendicularly to the paper  52  being advanced in the Advance Direction as shown by the arrows. Ink drops from compartment  16  ( FIG. 1 ) are caused to be ejected from the heater chip  25  at such times pursuant to commands of a printer microprocessor or other controller  57 . The timing of the ink drop emissions corresponds to a pattern of pixels of the image being printed. Often times, such patterns become generated in devices electrically connected to the controller  57  (via Ext. input) that reside externally to the printer and include, but are not limited to, a computer, a scanner, a camera, a visual display unit, a personal data assistant, or other. 
         [0034]    To print or emit a single drop of ink, the fluid firing elements (the dots of column  34 ,  FIG. 1 ) are uniquely addressed with a small amount of current to rapidly heat a small volume of ink. This causes the ink to vaporize in a local ink chamber between the heater and the nozzle plate and eject through, and become projected by, the nozzle plate towards the print medium. The fire pulse required to emit such ink drop may embody a single or a split firing pulse and is received at the heater chip on an input terminal (e.g., bond pad  28 ) from connections between the bond pad  28 , the electrical conductors  26 , the I/O connectors  24  and controller  57 . Internal heater chip wiring conveys the fire pulse from the input terminal to one or many of the fluid firing elements. 
         [0035]    A control panel  58 , having user selection interface  60 , also accompanies many printers as an input  62  to the controller  57  to provide additional printer capabilities and robustness. 
         [0036]      FIG. 3  is a block diagram showing the layout of a printhead, generally designated by reference number  100 , according to an exemplary embodiment of the present invention. Each heater A on the printhead  100  has a unique address having at minimum a two dimensional address matrix. The printhead  100  includes a fluid via  110  and groups P1-P10 (also referred to herein as “primitive groups”) of heaters A. The total number of heaters on the printhead is therefore P×A. In the examples shown in  FIG. 3 , each group P1-P10 includes 34 heaters for a total of 340 heaters for the via  110 . 
         [0037]    Table 1 illustrates three possible configurations for a 300 dpi, 600 dpi and 1200 dpi printhead. In each case, the print swath is about 1.13 inches and the number of heater addresses A is fixed at 34. It should be appreciated that the number of heaters per group, and hence the number of addresses A, need not be 34, and in other exemplary embodiments the number of heaters per group may be more or less than 34. For example, the number of heaters per group may be within a range of 8 to 40. As shown in Table 1, the only difference in addressing for the three chips is the number of primitives or P groups. 
         [0000]    
       
         
               
               
               
               
             
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 300 
                 600 
                 1200 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Number of Heaters per Column 
                 170 
                 340 
                 680 
               
               
                 Resolution per Via (dpi) 
                 300 
                 600 
                 1200 
               
               
                 Resolution per Column (dpi) 
                 150 
                 300 
                 600 
               
               
                 Heater Spacing (um) 
                 169.3 
                 84.7 
                 4.23 
               
               
                 Print Swath (in) 
                 1.136 
                 1.135 
                 1.133 
               
               
                 Number of Heaters per Via 
                 340 
                 680 
                 1360 
               
               
                 Number of Addresses 
                 34 
                 34 
                 34 
               
               
                 Number of Primitives 
                 10 
                 20 
                 40 
               
               
                   
               
             
          
         
       
     
         [0038]    By fixing the number of addresses at 34, the length of the on chip register required to contain the encoded value is fixed at 6 bits (so as to encode the decimal value of each of the 34 addresses). This will be the case for all three resolutions, thereby allowing for a common electrical interface for the address data. 
         [0039]    In the 1200 dpi case, the number of primitives is set at 40, so that in order to address each primitive, a total of 40 bits is required.  FIG. 4  illustrates the addressing for the 1200 dpi case. As shown, the primitive groups P1-P40 of printhead  300  are addressed using two shift registers, with one bit for each primitive group. There are a total of 40 P data  bits divided into the two registers Shift Register 1 and Shift Register 2 for 20 bits per register. 
         [0040]      FIG. 5  illustrates the addressing for the 600 dpi case. Since half as many addresses are needed as compared to the 1200 dpi case, the number of primitives of printhead  400  can be set at 20, which is half as many primitives used in the 1200 dpi case. The P data  bit shift register used in the 1200 dpi case can also be used in the 600 dpi case. However, each four element R1-R 4 group within the shift register can now be used to address a corresponding pair of primitives instead of a corresponding group of four primitives. 
         [0041]      FIG. 6  illustrates the addressing for the 300 dpi case. Since only ¼ as many addresses are needed as compared to the 1200 dpi case, the number of primitives of printhead  500  can be set at 10, which is ¼ as many primitives used in the 1200 dpi case. The P data  bit shift register used in the 1200 dpi case can also be used in the 300 dpi case. However, each four element R1-R4 group within the shift register can now be used to address a single primitive instead of a corresponding group of four primitives. 
         [0042]    Further exploring the 300 dpi case, and as described in U.S. patent application Ser. No. 14/472,297 (attorney docket number 35968/1048), the contents of which are incorporated herein by reference in their entirety,  FIG. 7  shows four power FETs, FET1, FET2, FET3 and FET4 connected in parallel and available to drive a single heater element A. Each power FET has a corresponding pre-drive circuit (not shown) used to charge (turn on) and discharge (turn off) the FET to switch heater current when addressed. By maintaining a unique pre-drive and register bit for each FET and tying the FETs in parallel, the heater chip driving circuit can now select the drive strength which best fits the application. The ability to select the drive strength allows the heater chip control circuit to shape the firing current rise and fall times. 
         [0043]    Table 2 shows the values for selecting primitive groups for the 300, 600 and 1200 dpi cases. Shown are the minimum values needed to select all primitives where the X parameters represent cases where the drive strength could be increased if desired. 
         [0000]    
       
         
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
               
                   
                   
                 R20 
                 R19 
                 R18 
                 R17 
                 R16 
                 R15 
                 R14 
                 R13 
                 R12 
                 R11 
                 R10 
                 R9 
                 R8 
                 R7 
                 R6 
                 R5 
                 R4 
                 R3 
                 R2 
                 R1 
               
               
                   
               
             
             
               
                 1200 dpi 
                 Pdata1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
               
               
                   
                 Pdata2 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
               
               
                  600 dpi 
                 Pdata1 
                 X 
                 1 
                 X 
                 1 
                 X 
                 1 
                 X 
                 1 
                 X 
                 1 
                 X 
                 1 
                 X 
                 1 
                 X 
                 1 
                 X 
                 1 
                 X 
                 1 
               
               
                   
                 Pdata2 
                 X 
                 1 
                 X 
                 1 
                 X 
                 1 
                 X 
                 1 
                 X 
                 1 
                 X 
                 1 
                 X 
                 1 
                 X 
                 1 
                 X 
                 1 
                 X 
                 1 
               
               
                  300 dpi 
                 Pdata1 
                 X 
                 X 
                 X 
                 1 
                 X 
                 X 
                 X 
                 1 
                 X 
                 X 
                 X 
                 1 
                 X 
                 X 
                 X 
                 1 
                 X 
                 X 
                 X 
                 1 
               
               
                   
                 Pdata2 
                 X 
                 X 
                 X 
                 1 
                 X 
                 X 
                 X 
                 1 
                 X 
                 X 
                 X 
                 1 
                 X 
                 X 
                 X 
                 1 
                 X 
                 X 
                 X 
                 1 
               
               
                   
               
             
          
         
       
     
         [0044]    Further considering the 300 dpi case, Table 3 shows the values for selecting minimum drive strength while Table 4 shows the values for selecting maximum drive strength. 
         [0000]    
       
         
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 3 
               
               
                   
               
               
                   
                   
                 R20 
                 R19 
                 R18 
                 R17 
                 R16 
                 R15 
                 R14 
                 R13 
                 R12 
                 R11 
                 R10 
                 R9 
                 R8 
                 R7 
                 R6 
                 R5 
                 R4 
                 R3 
                 R2 
                 R1 
               
               
                   
               
             
             
               
                 300 dpi 
                 Pdata1 
                 0 
                 0 
                 0 
                 1 
                 0 
                 0 
                 0 
                 1 
                 0 
                 0 
                 0 
                 1 
                 0 
                 0 
                 0 
                 1 
                 0 
                 0 
                 0 
                 1 
               
               
                   
                 Pdata2 
                 0 
                 0 
                 0 
                 1 
                 0 
                 0 
                 0 
                 1 
                 0 
                 0 
                 0 
                 1 
                 0 
                 0 
                 0 
                 1 
                 0 
                 0 
                 0 
                 1 
               
               
                   
               
             
          
         
       
     
         [0000]    
       
         
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 4 
               
               
                   
               
               
                   
                   
                 R20 
                 R19 
                 R18 
                 R17 
                 R16 
                 R15 
                 R14 
                 R13 
                 R12 
                 R11 
                 R10 
                 R9 
                 R8 
                 R7 
                 R6 
                 R5 
                 R4 
                 R3 
                 R2 
                 R1 
               
               
                   
               
             
             
               
                 300 dpi 
                 Pdata1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
               
               
                   
                 Pdata2 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
               
               
                   
               
             
          
         
       
     
         [0045]    In this example, to maintain a common electrical interface the Pdata register for all three cases would be fixed to the 20 bits. 
         [0046]    While particular embodiments of the invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications may be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.