Abstract:
A configurable printhead that includes a plurality of potential signal inputs. The printhead preferably contains logic that is responsive to a signal from a printer controller or elsewhere that specifies the number potential signal inputs that are going to be used for signal (data) transmission. Configurability of the input lines and clock speeds permits use of the printhead in a range of printer environments and may serve to reduce EMI. Printer arrangements and a processing method are also disclosed.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to printers and printerheads and, more specifically, to configurable printer and printhead arrangements.  
         BACKGROUND OF THE INVENTION  
         [0002]    Many types of printers are known and they include ink jet, laser and various thermal and impact printers. Ink jet printers include those that are thermally actuated (e.g., resistive element) and those that are mechanically actuated (e.g., piezo-electric element). Representative ink jet printers include those made by Hewlett Packard, Canon and Epson, etc. The present invention is applicable to all printers and particularly to ink jet printers.  
           [0003]    In a representative prior art ink jet printer, control logic and other components propagate signals to a printhead. These signals typically include a clock signal, power, print data and configuration information, etc. The printhead is typically mounted on a moveable carriage and the signals are delivered by a flexible cable or the like.  
           [0004]    The number of signal lines, the speed of data transmission and the type of signal conductors, amongst other design features, may vary depending on the intended use of the printer. For example, in an environment where EMI is not of particular concern (e.g., slow clock rates, etc.) and/or there are plenty of available connecting leads, a ribbon cable may be used to connect to the printhead. When EMI is of concern, then more expensive co-axial leads or the like may be utilized. Furthermore, when connecting lead availability is limited, then a high speed serial conductor may be utilized as opposed to multiple lower speed conductors.  
           [0005]    Thus, conventional printheads are designed to have a specific configuration that naturally corresponds to their intended purpose. These printheads cannot readily be used in other printing devices, however, that perform a different function or operate in a different environment. A new printhead must be designed and built for the new function or environment.  
           [0006]    A need thus exists for a printhead that is configurable for use in a range of printer environments/configurations. A need also exists for a printhead that is configurable so as to reduce EMI.  
         SUMMARY OF THE INVENTION  
         [0007]    Accordingly, it is an object of the present invention to provide a printhead in which signal lines coupling to the printhead may be configured into a desired format.  
           [0008]    It is another object of the present invention to provide a printhead that permits a user to select parameters such as transfer rate and number of transmission lines so as to reduce EMI.  
           [0009]    It is also an object of the present invention to provide a printer that incorporates and/or facilitates use of such a printhead.  
           [0010]    These and related objects of the present invention are achieved by use of a configurable printhead apparatus and method as described herein.  
           [0011]    The attainment of the foregoing and related advantages and features of the invention should be more readily apparent to those skilled in the art, after review of the following more detailed description of the invention taken together with the drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    [0012]FIG. 1 is a schematic diagram of a printer and printhead in accordance with the present invention.  
         [0013]    [0013]FIG. 2 is a cross-sectional view of a representative firing chamber for use in the printhead of FIG. 1 in accordance with the present invention.  
         [0014]    [0014]FIG. 3 is a schematic diagram of demultiplexing and configuration logic in accordance with the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0015]    Referring to FIG. 1, a schematic diagram of a printer and printhead in accordance with the present invention is shown. Printer  10  preferably includes a housing  12  in which are provided print media input/output (I/O) unit  14 , a power supply  16 , an ink supply  18 , controller logic  25  and a printhead  40 , amongst other related components. The print media I/O unit preferably includes paper input and output trays, guides, and appropriate sensors and transport mechanisms, etc. Power supply  16  provides regulated DC at appropriate voltage levels.  
         [0016]    Ink supply  18  may be formed integrally with printhead  10  or formed separately. Ink supply  18  may be provided in a refillable or replaceable manner. Ink level detection logic  19  is preferably provided with ink supply  18  to indicate an ink volume level. Suitable ink supply arrangements are known in the art.  
         [0017]    Printer  10  preferably receives print data from a host machine  5  which may be a computer, facsimile machine, Internet terminal, camera, plotter or other device that is capable of propagating print data to printer  10 .  
         [0018]    Printhead  40  is preferably provided on a moveable carriage  41  that may move transversely along guide rods as is known. Transverse motion is indicated by two headed arrow A. It should be recognized, however, that printhead  40  could be stationary and, for example, formed as wide as a sheet (or section of a sheet) of print media, such as paper.  
         [0019]    Printhead  40  preferably includes a substrate  42  of a semiconductive or other suitable material on/in which are formed a plurality of firing chambers  80  (shown in FIG. 2) each preferably with an associated ink expulsion point or nozzle  44 . The nozzles may be grouped into primitives  45  which are subsets of nozzles in which only one nozzle (or less than all nozzles) is fired per firing interval. While FIG. 1 illustrates four nozzles per primitive, more of less than this number may be provided. The use of primitives may decrease power consumption and lead interconnects and may address fluidic concerns.  
         [0020]    Referring to FIG. 2, a cross-sectional view of a representative firing chamber  80  for use in printhead  40  of FIG. 1 is shown. The term firing chamber refers generally to the collection of components that expel an ink drop. Suitable firing chambers are known in the art and include firing chambers having different components and configurations than shown in FIG. 2. Firing chamber  80  includes an orifice layer  81 , in which nozzle  44  is formed, a barrier layer  82  that helps define ink well  83 , a passivation layer (or like protection layer)  84  and an ink expulsion element  85  such as a resistor or mechanical actuator or the like. A firing signal is delivered to the expulsion element via conductive material  89 . The above components are preferably formed on a semiconductive substrate  86 .  
         [0021]    The firing chamber of each nozzle preferably receives a firing signal and a nozzle select signal. Such configurations are known in the art.  
         [0022]    Referring again to FIG. 1, nozzle select data is preferably delivered over any, some or all of lines  51 - 54  (discussed in more detail below). These lines are input to demultiplexing (demux) logic  60  and a single stream of print data is preferably output from the demux logic (over line  49 ) and delivered to the firing chambers. Which of lines  51 - 54  is used for signal transmission is preferably determined by a code loaded into configuration register  62 . This code is transmitted over line(s)  56 . A master clock signal is preferably delivered over line  57 . Other printhead configuration data, as is known in the art, is preferably provided to the printhead over line(s)  59 . This other data may include nozzle fire order, set point temperature, scan direction, etc. Logic for implementing and processing these other features is represented with reference numeral  63 .  
         [0023]    Configuration register  62  in conjunction with demux logic  60  and the master clock signal permits a selection of which of the print data lines to use in a given printhead implementation. For example, if EMI is not a significant consideration, it is conceivable that a single secure conductor such as a co-axial conductor (or other conductor) could be provided at line  51  and the demux logic setup to stream this serial data directly through to the nozzles (over line  49 ).  
         [0024]    In another implementation, it is conceivable that to reduce EMI, print data is split, for example, into four components and each component is sent at 1 MHz (as opposed to sending an undivided print data signal at 4 MHz). The demux logic (using the clock signal and configuration register value as a guide) then assembles the four components into a stream at 4 MHz that is fed to the nozzles.  
         [0025]    In this latter implementation, the print data signal is divided or generated in component parts in controller logic  25 . Logic for generating print data in a divided or component format, termed generation logic  28 , may include a multiplexer or serial to parallel shift register or other suitable logic. Controller  25  controls which of data lines  51 - 54  propagate data and sends an appropriate clock signal over line  57 .  
         [0026]    Referring to FIG. 3, a schematic diagram of demux and configuration logic in accordance with the present invention is shown. This logic preferably includes configuration register  62 , next state logic  64 , state register  65 , zero detect logic  67  and shift register  70 . Operation is generally as follows for an embodiment in which four possible data transfer lines are provided.  
         [0027]    A value indicative of the number (e.g., 1-4) of transmission lines  51 - 54  to use in data transmission is propagated from controller logic  25  to configuration logic  62 . These values may be 00,01,10,11 (or more, if more data lines are utilized). If, for example, all four lines are going to be used and the master clock signal is at 4 MHz, then data is preferably sent on each of lines  51 - 54  at 1 MHz. This results in a significant EMI reduction compared to sending the data on one line at 4 MHz.  
         [0028]    If three of lines  51 - 54  are used, then signals are propagated on the utilized lines at 1.33 MHz, and if two of lines  51 - 54  are used, then signals are propagated on the utilized lines at 2 MHz.  
         [0029]    The next state and state register logic are preferably configured to effectively form a count down counter. The configuration register is loaded with a value and the counter counts down from this value until zero is reached. Zero detect logic  67  recognizes this event and in response generates a latch signal that achieves a new load of data from lines  51 - 54  (or those of lines  51 - 54  that are activated) into shift register  70 .  
         [0030]    The master clock signal is also coupled to shift register  70 . A bit is preferably shifted out with each occurrence of the master clock signal.  
         [0031]    If, for example, a two (01) were loaded into configuration register  62 , then locations  73  and  74  of shift register  70  would not be used. If 00 were loaded, then only location  71  would be used and the shift register latch and an output clock signal would occur at each master clock interval.  
         [0032]    It should be recognized that the demux and configuration logic can be configured to latch on the positive and the negative transitions of the clock signal. This would permit, in the above example with 4 data lines, the use of a 2 MHz clock signal as opposed to a 4 MHz clock signal. This would reduce EMI caused by the clock signal. In addition, or alternatively, a phase locked loop  91  or the like (see FIG. 1) could be provided within the clock signal path to increase the frequency of the clock signal in the printhead. This permits propagation of a slower clock signal over line  57 , and thus further reduces EMI.  
         [0033]    While the invention has been described in connection with specific embodiments thereof, it will be understood that it is capable of further modification, and this application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice in the art to which the invention pertains and as may be applied to the essential features hereinbefore set forth, and as fall within the scope of the invention and the limits of the appended claims.