Abstract:
A printing fluid dispenser that has a housing with first and second portions, the first portion being displaceable relative to the second portion. A quantity of printing fluid is contained in the housing and a resilient member deforms in response to displacement of the first portion relative to the second portion to apply pressure to the printing fluid such that it dispenses from an outlet. The first portion has a maximum displacement relative to the second portion, which is designed to correspond with a maximum possible pressure applied by the resilient member to the printing fluid.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This is a continuation of U.S. application Ser. No. 10/760,195 filed on Jan. 21, 2004 all of which are herein are incorporated by reference.  
       CROSS-REFERENCE TO CO-PENDING APPLICATIONS  
       [0002]     The following applications have been filed by the Applicant simultaneously with the present application:  
                                                       7156508   7159972   7083271   7165834   7080894   7201469       7090336   7156489   10/760233   10/760246   7083257   10/760243       10/760201   10/760185   10/760253   10/760255   10/760209   7118192       10/760194   10/760238   7077505   7198354   7077504   10/760189       7198355   10/760232   10/760231   7152959   7213906   7178901       10/760227   7108353   7104629   10/760254   10/760210   10/760202       7201468   10/760198   10/760249   10/760263   10/760196   10/760247       7156511   10/760264   10/760244   7097291   10/760222   10/760248       7083273   10/760192   10/760203   10/760204   10/760205   10/760206       10/760267   10/760270   7198352   10/760271   10/760275   7201470       7121655   10/760184   10/760186   10/760261   7083272   10/760180       7111935   10/760213   10/760219   10/760237   10/760221   10/760220       7002664   10/760252   10/760265   10/760230   7168654   7201272       6991098   10/760228   6944970   10/760215   7108434   10/760257       7210407   7186042   10/760266   6920704   10/760193   10/760214       10/760260   7147102   10/760269   10/760199   10/760241                  
 
 The disclosures of these co-pending applications are incorporated herein by reference.
 
     
    
     FIELD OF THE INVENTION  
       [0003]     The present invention relates to a printer system and in particular to a printing fluid dispenser for refilling removable printer cartridge for an inkjet printer system.  
       BACKGROUND OF THE INVENTION  
       [0004]     Traditionally, most commercially available inkjet printers employ a printhead that traverse back and forth across the width of the print media as it prints. Such a print head is supplied with ink for printing and typically has a finite life, after which replacement of the printhead is necessary. Replacement of the printhead may be necessary due to degradation of the printhead through usage and in some cases the printhead may require placement following depletion of the ink supply. Due to the size and configuration of the traversing printhead, removal and replacement of this element is relatively easy, and the printer unit is designed to enable easy access to this element. Whilst printer systems employing such traditional traversing printheads have proven capable of performing printing tasks to a sufficient quality, as the printhead must continually traverse the stationary print media, such systems are typically slow, particularly when used to perform print jobs of photo quality.  
         [0005]     Recently, it has been possible to provide printheads that extend the entire width of the print media so that the printhead remains stationary as the print media progresses past. Such printheads are typically referred to as pagewidth printheads, and as the printhead does not move back and forth across the print media, much higher printing speeds are possible with this printhead than with traditionally traversing printheads. However as the printhead is the length of the print media, it must be supported within the structure of the printer unit and requires multiple electrical contacts to deliver power and data to drive the printhead, and as such removal and replacement of the printhead is not as easy as with traditional traversing printheads.  
         [0006]     Accordingly, there is a need to provide a printer system that is capable of providing high quality print jobs at high speeds and which facilitates relatively easy replacement of the printhead when necessary. There is also a need to provide such a printer system that can be readily re-filled with printing fluid when desired via an easy to use fluid dispensing system, thereby overcoming the need to replace the components of the printer following depletion of the ink supply.  
       SUMMARY OF THE INVENTION  
       [0007]     Accordingly, in one embodiment of the present invention there is provided a printing fluid dispenser including: 
        A housing comprising first and second portions movable relative to each other;     A reservoir of printing fluid responsive to relative motion of the first and second portions and having an outlet arranged to convey the printing fluid to a point external to the housing; wherein in use bringing the first and second portions towards each other causes egress of the printing fluid through the outlet.        
 
         [0010]     Preferably, the reservoir comprises a deformable container located within the housing and in the event of bringing the first and second portions towards each other, the deformable container compresses.  
         [0011]     The first and second portions of the housing are preferably arranged to slide over each other and a resilient member is preferably disposed between the deformable container and either or both of the first and second portions of the housing. The resilient member preferably has characteristics selected to limit pressure in the deformable container to a predetermined level in use.  
         [0012]     The resilient member may comprise a spring and the first and second portions of the housing may comprise a base and plunger, wherein the spring is located between the deformable container and the plunger.  
         [0013]     The deformable container preferably comprises a deformable membrane.  
         [0014]     In another embodiment of the present invention there is provided a printing fluid dispenser including: 
        a housing comprising a base and a plunger;     a deformable container located within the housing for storing printing fluid;     an outlet coupled to the deformable container and arranged to convey the printing fluid to a point external to the housing; and     a spring located between the deformable container and the plunger having characteristics selected to limit pressure in the deformable container to a predetermined level in use; wherein     in use, bringing the plunger towards the base causes compression of the deformable container between the spring and the base and egress of the printing fluid through the outlet.        
 
         [0020]     It will be appreciated that the printing fluid dispenser of the present invention provides a means for dispensing a range of printing fluids to refill an external reservoir, such as a storage reservoir in an inkjet printer cartridge having a pagewidth printhead. The dispenser employs an easy to use plunging mechanism to expel fluid from the dispenser into an external reservoir to ensure a simple and effective mechanism for refilling the printing fluid in an inkjet printer system. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0021]      FIG. 1  is a perspective view, showing front, top and right-hand sides of a printer cartridge according to a preferred embodiment of the present invention in combination with a printer cradle.  
         [0022]      FIG. 2  is a block diagram of the printer cartridge.  
         [0023]      FIG. 3  is a perspective view, showing front, top and right-hand sides of the printer cartridge prior to insertion into the printer cradle.  
         [0024]      FIG. 4  is a perspective view, showing rear, bottom and left-hand sides of the printer cartridge.  
         [0025]      FIG. 5  is a perspective view, showing, front, bottom and right-hand, sides of the printer cartridge in a partly dismantled state.  
         [0026]      FIG. 6  is a perspective view, showing front, bottom and right-hand sides of the printer cartridge in an exploded state.  
         [0027]      FIG. 7  is a plan view of the underside of a base molding of the cartridge revealing a number printing fluid conduits.  
         [0028]      FIG. 8  is a right-hand plan view of the printer cartridge.  
         [0029]      FIG. 9  is a cross-sectional view of the printer cartridge.  
         [0030]      FIG. 10  is a cross sectional view through a printhead chip nozzle in a first state of operation.  
         [0031]      FIG. 11  is a cross sectional view through the printhead chip nozzle in a second state of operation.  
         [0032]      FIG. 12  is a cross sectional view through a printhead chip nozzle subsequent to ejection of an ink droplet.  
         [0033]      FIG. 13  is a perspective, and partially cutaway, view of a printhead chip nozzle subsequent to ejection of an ink droplet.  
         [0034]      FIG. 14  is a perspective cross section of a printhead chip nozzle.  
         [0035]      FIG. 15  is a cross section of a printhead chip nozzle.  
         [0036]      FIG. 16  is a perspective and partially cutaway perspective view of a printhead chip nozzle.  
         [0037]      FIG. 17  is a plan view of a printhead chip nozzle.  
         [0038]      FIG. 18  is a plan, and partially cutaway view of a printhead chip nozzle.  
         [0039]      FIG. 19  is a perspective cross-sectioned view of a portion of a printhead chip.  
         [0040]      FIG. 20  is a block diagram of the printer cradle.  
         [0041]      FIG. 21  is a perspective, front, left-hand, upper side view of the printer cradle.  
         [0042]      FIG. 22  is a front plan view of the printer cradle.  
         [0043]      FIG. 23  is a top plan view of the printer cradle.  
         [0044]      FIG. 24  is a bottom plan view of the printer cradle.  
         [0045]      FIG. 25  is a right-hand plan view of the printer cradle.  
         [0046]      FIG. 26  is a perspective view of the left-hand, front and top sides of the printer cradle in an exploded state.  
         [0047]      FIG. 27  is a right-hand, and partially cutaway, plan view of the printer cradle.  
         [0048]      FIG. 28  is a perspective, rear left-hand and upper view of the printer cradle with print cartridge inserted.  
         [0049]      FIG. 29  is a perspective, rear left-hand and upper side view of the printer cradle with RFI shield removed.  
         [0050]      FIG. 30  is a perspective detail view of a portion of the left-hand side of the printer cradle.  
         [0051]      FIG. 31  is a perspective detail view of a portion of the right-hand side of the printer cradle.  
         [0052]      FIG. 32  is a perspective view of a single SoPEC chip controller board.  
         [0053]      FIG. 33  is a perspective view of a twin SoPEC chip controller board.  
         [0054]      FIG. 34  is a block diagram of a SoPEC chip.  
         [0055]      FIG. 35  is a perspective view of an ink refill cartridge in an emptied state.  
         [0056]      FIG. 36  is a perspective view of the ink refill cartridge in a full state.  
         [0057]      FIG. 37  is a perspective view of the ink refill cartridge in an exploded state.  
         [0058]      FIG. 38  is a cross section of the ink refill cartridge in an emptied state.  
         [0059]      FIG. 39  is a cross section of the ink refill cartridge in a full state.  
         [0060]      FIG. 40  depicts a full ink refill cartridge aligned for docking to a printer cartridge.  
         [0061]      FIG. 41  depicts the ink refill cartridge docked to a printer cartridge prior to dispensing ink.  
         [0062]      FIG. 42  depicts the ink refill cartridge docked to a printer cartridge subsequent to dispensing ink. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0063]      FIG. 1  depicts an inkjet printer  2  which includes a cradle  4  that receives a replaceable print cartridge  6  into a recess formed in the cradle&#39;s body according to a preferred embodiment of the present invention. Cartridge  6  is secured in the cradle recess by a retainer in the form of latch  7  that is connected by a hinge to cradle  4 .  
         [0064]     Visible on the upper surface of print cartridge  6  is an ink refill port  8  which receives an ink refill cartridge during use.  
         [0000]     Print Cartridge  
         [0065]     Referring now to  FIG. 2 , there is depicted a block diagram of removable inkjet printer cartridge  6 . Cartridge  6  includes ink refill port  8  and an ink delivery assembly  10  for storing and delivering ink to a micro-electromechanical pagewidth print head chip  52 . Printhead chip  52  receives power and data signals from cradle  4  (see  FIG. 1 ) via power and data interface  58 . A rotor element  60 , which is mechanically driven by cradle  4  has three faces which respectively serve to: blot printhead chip  52  subsequent to ink ejection; seal the printhead when it is not in use; and act as a platen during printing. Accordingly, rotor element  60  acts as an auxiliary assembly to the printhead in that it assists in maintaining proper printhead functioning. Cartridge  6  also includes an authentication device in the form of quality assurance chip  57  which contains various manufacturer codes that are read by electronic circuitry of controller board  82  of cradle [[ ]]during use. The manufacturer codes are read to verify the authenticity of cartridge  6 .  
         [0066]     With reference to FIGS.  3  to  9 , and initially to  FIG. 6 , structurally cartridge  6  has a body including a base molding  20  that houses a polyethylene membrane  26  including ink storage reservoirs in the form of pockets  28 ,  30 ,  32 ,  34  for each of four different printing fluids. Typically the printing fluids will be cyan, magenta, yellow and black inks. Additional storage reservoirs may also be provided within base molding  20  in order to receive and store an ink fixative and/or an infrared ink as various applications may require. In this regard there may be up to six storage reservoirs provided with base molding  20 . As membrane  26  is filled with printing fluids it expands and conversely, as ink is consumed during printing the membrane collapses.  
         [0067]     Cover molding  36  includes a recess  38  that receives an ink inlet molding  24  having a number of passageways. A number of apertures  42 A- 42 E are formed through recess  38  and are arranged to communicate with corresponding passageways of ink inlet molding  24 . The passages of the ink inlet member convey ink from an externally fitted ink refill cartridge to each of the ink storage reservoirs via a series of ink delivery paths formed into ink membrane  26 . The ink delivery paths connect each aperture  42 A- 42 E of the ink inlet member  24  to its dedicated ink storage reservoir  28 - 34 . The ink is typically delivered under pressure thereby causing it to flow into and expand the reservoirs of membrane  26 . An ink inlet seal  40  is located over the outside of recess  38  in order to seal apertures  42 A- 42 E prior to use.  
         [0068]     Pagewidth printhead chip  52  is disposed along the outside of cartridge base molding  20  in the region below the ink storage reservoirs. As shown in  FIG. 7 , a number of conduits  43 A- 43 E are formed in the underside of the cartridge base molding and are in direct communication with each of ink storage reservoirs  28 ,  30 ,  32 ,  34 . The conduits provide an ink delivery path from the underside of cartridge base molding  20  to inlet ports provided in ink delivery moldings  48  onto which the printhead chip  52  is attached.  
         [0069]     Referring again to  FIG. 6 , ink delivery moldings  48  are preferably made from a plastic, such as LCP (Liquid Crystal Polymer) via an injection molding process and include a plurality of elongate conduits disposed along the length thereof arranged to distribute printing fluids from the reservoirs in membrane  26  to printhead chip  52 . Each of the elongate conduits are dedicated to carry a specific fluid, such as a particular color ink or a fixative and to allow the fluid to be distributed along the length of the printhead. To assist in controlled delivery of the printing fluid an ink sealing strip  45  is placed between cartridge base molding  20  and ink delivery molding  48 . The ink sealing strip is formed with apertures that allow fluid transfer to occur between the two elements, however the strip acts to seal the channels formed in the cartridge base molding to prevent fluid leakage.  
         [0070]     Formed in cartridge base molding  20  adjacent the elongate ink distribution conduits, is an air distribution channel  50  that acts to distribute pressurized air from air inlet port  76  over the nozzles of printhead  52 . The air distribution channel runs along the length of printhead  52  and communicates with air inlet port  76 . A porous air filter  51  extends along the length of air distribution channel  50  and serves to remove dust and particulate matter that may be present in the air and which might otherwise contaminate printhead  52 . Porous air filter  51  has a selected porosity so that only air at a desired threshold pressure is able to pass through it, thereby ensuring that the air is evenly delivered at a constant pressure along the length of the printhead. In use, channel  50  firstly fills with compressed air until it reaches the threshold pressure within the channel. Once the threshold pressure is reached the air is able to pass through porous air filter  51  evenly along the length of the filter. The filtered air is then directed over the printhead.  
         [0071]     The purpose of the pressurized air is to prevent degradation of the printhead by keeping its nozzles free of dust and debris. The pressurized air is provided by an air compressor (item  122  of  FIG. 13 ) incorporated into cradle  4 . An air nozzle (item  124  of  FIG. 13 ) of the compressor pierces air seal  44  upon insertion of cartridge  6  into cradle  4  and mates with air inlet port  76 . An air coverplate  54  is fixed to the cartridge base molding and evenly distributes air across printhead  52  in the manner described above.  
         [0072]     Power and data signals are provided to printhead  52  by means of busbar  56  which is in turn coupled to external data and power connectors  58 A and  58 B. An authentication device in the form of a quality assurance (QA) chip  57  is mounted to connector  58 A. Upon inserting print cartridge  6  into cradle  4  the data and power connectors  58 A and  58 B, and QA chip  57 , mate with corresponding connectors (items  84 A,  84 B of  FIG. 3 ) on cradle  4 , thereby facilitating power and data communication between the cradle and the cartridge. QA chip  57  is tested in use by a portion of controller board  82  configured to act as a suitable verification circuit.  
         [0073]     Rotor element  60  is rotatably mounted adjacent and parallel to printhead  52 . The rotor element has three faces, as briefly explained previously, as follows: a platen face, which during printing acts as a support for print media and assists in bringing the print media close to printhead  52 ; a capping face for capping the printhead when not in use in order to reduce evaporation of printing fluids from the nozzles; and a blotter face, for blotting the printhead subsequent to a printing operation. The three faces of the rotor element are each separated by 120 degrees.  
         [0074]     At opposite ends of rotor element  60  there extend axial pins  64 A and  64 B about which are fixed cogs  62 A and  62 B respectively. The free ends of axial pins  64 A and  64 B are received into slider blocks  66 A and  66 B. Slider blocks  66 A and  66 B include flanges  68 A and  68 B which are located within slots  70 A and  70 B of end plates  22 A and  22 B. The end plates are fixed at either end of cartridge base molding  20 .  
         [0075]     Slider blocks  66 A and  66 B are biased towards the printhead end of slots  70 A and  70 B by springs  72 A and  72 B held at either end by their insertion into blind holes in slider block  66 A and  66 B and by their seating over protrusions into slots  70 A and  70 B as best seen in  FIG. 8 . Accordingly, rotor element  60  is normally biased so it is brought closely adjacent to printhead  52 . During transport, and whilst printer cartridge  6  is being inserted into cradle  4 , rotor element  60  is arranged so that its capping face caps printhead  52  in order to prevent the surrounding air from drying out the printhead&#39;s nozzles.  
         [0000]     Printhead  
         [0076]     A preferred design for pagewidth printhead  52  will now be explained. A printhead of the following type may be fabricated with a width of greater than eight inches if desired and will typically include at least 20,000 nozzles and in some variations more than 30,000. The preferred printhead nozzle arrangement, comprising a nozzle and corresponding actuator, will now be described with reference to FIGS.  10  to  19 .  FIG. 19  shows an array of the nozzle arrangements  801  formed on a silicon substrate  8015 . The nozzle arrangements are identical, but in the preferred embodiment, different nozzle arrangements are fed with different colored inks and fixative. It will be noted that rows of the nozzle arrangements  801  are staggered with respect to each other, allowing closer spacing of ink dots during printing than would be possible with a single row of nozzles. The multiple rows also allow for redundancy (if desired), thereby allowing for a predetermined failure rate per nozzle.  
         [0077]     Each nozzle arrangement  801  is the product of an integrated circuit fabrication technique. In particular, the nozzle arrangement  801  defines a micro-electromechanical system (MEMS).  
         [0078]     For clarity and ease of description, the construction and operation of a single nozzle arrangement  801  will be described with reference to FIGS.  10  to  18 .  
         [0079]     The ink jet printhead chip  52  (see  FIG. 6 ) includes a silicon wafer substrate  8015 . 0.35 Micron 1 P4M 12 volt CMOS microprocessing circuitry is positioned on the silicon wafer substrate  8015 .  
         [0080]     A silicon dioxide (or alternatively glass) layer  8017  is positioned on the wafer substrate  8015 . The silicon dioxide layer  8017  defines CMOS dielectric layers. CMOS top-level metal defines a pair of aligned aluminium electrode contact layers  8030  positioned on the silicon dioxide layer  8017 . Both the silicon wafer substrate  8015  and the silicon dioxide layer  8017  are etched to define an ink inlet channel  8014  having a generally circular cross section (in plan). An aluminium diffusion barrier  8028  of CMOS metal  1 , CMOS metal  2 / 3  and CMOS top level metal is positioned in the silicon dioxide layer  8017  about the ink inlet channel  8014 . The diffusion barrier  8028  serves to inhibit the diffusion of hydroxyl ions through CMOS oxide layers of the drive circuitry layer  8017 .  
         [0081]     A passivation layer in the form of a layer of silicon nitride  8031  is positioned over the aluminium contact layers  8030  and the silicon dioxide layer  8017 . Each portion of the passivation layer  8031  positioned over the contact layers  8030  has an opening  8032  defined therein to provide access to the contacts  8030 .  
         [0082]     The nozzle arrangement  801  includes a nozzle chamber  8029  defined by an annular nozzle wall  8033 , which terminates at an upper end in a nozzle roof  805  and a radially inner nozzle rim  804  that is circular in plan. The ink inlet channel  8014  is in fluid communication with the nozzle chamber  8029 . At a lower end of the nozzle wall, there is disposed a moving rim  8010 , that includes a moving seal lip  8040 . An encircling wall  8038  surrounds the movable nozzle, and includes a stationary seal lip  8039  that, when the nozzle is at rest as shown in  FIG. 10 , is adjacent the moving rim  8010 . A fluidic seal  8011  is formed due to the surface tension of ink trapped between the stationary seal lip  8039  and the moving seal lip  8040 . This prevents leakage of ink from the chamber whilst providing a low resistance coupling between the encircling wall  8038  and the nozzle wall  8033 .  
         [0083]     As best shown in  FIG. 17 , a plurality of radially extending recesses  8035  is defined in the roof  805  about the nozzle rim  804 . The recesses  8035  serve to contain radial ink flow as a result of ink escaping past the nozzle rim  804 .  
         [0084]     The nozzle wall  8033  forms part of a lever arrangement that is mounted to a carrier  8036  having a generally U-shaped profile with a base  8037  attached to the layer  8031  of silicon nitride.  
         [0085]     The lever arrangement also includes a lever arm  8018  that extends from the nozzle walls and incorporates a lateral stiffening beam  8022 . The lever arm  8018  is attached to a pair of passive beams  806 , formed from titanium nitride (TiN) and positioned on either side of the nozzle arrangement, as best shown in  FIGS. 13 and 18 . The other ends of the passive beams  806  are attached to the carrier  8036 .  
         [0086]     The lever arm  8018  is also attached to an actuator beam  807 , which is formed from TiN. It will be noted that this attachment to the actuator beam is made at a point a small but critical distance higher than the attachments to the passive beam  806 .  
         [0087]     As best shown in  FIGS. 13 and 16 , the actuator beam  807  is substantially U-shaped in plan, defining a current path between the electrode  809  and an opposite electrode  8041 . Each of the electrodes  809  and  8041  are electrically connected to respective points in the contact layer  8030 . As well as being electrically coupled via the contacts  809 , the actuator beam is also mechanically anchored to anchor  808 . The anchor  808  is configured to constrain motion of the actuator beam  807  to the left of FIGS.  10  to  12  when the nozzle arrangement is in operation.  
         [0088]     The TiN in the actuator beam  807  is conductive, but has a high enough electrical resistance that it undergoes self-heating when a current is passed between the electrodes  809  and  8041 . No current flows through the passive beams  806 , so they do not expand.  
         [0089]     In use, the device at rest is filled with ink  8013  that defines a meniscus  803  under the influence of surface tension. The ink is retained in the chamber  8029  by the meniscus, and will not generally leak out in the absence of some other physical influence.  
         [0090]     As shown in  FIG. 11 , to fire ink from the nozzle, a current is passed between the contacts  809  and  8041 , passing through the actuator beam  807 . The self-heating of the beam  807  due to its resistance causes the beam to expand. The dimensions and design of the actuator beam  807  mean that the majority of the expansion in a horizontal direction with respect to FIGS.  10  to  12 . The expansion is constrained to the left by the anchor  808 , so the end of the actuator beam  807  adjacent the lever arm  8018  is impelled to the right.  
         [0091]     The relative horizontal inflexibility of the passive beams  806  prevents them from allowing much horizontal movement the lever arm  8018 . However, the relative displacement of the attachment points of the passive beams and actuator beam respectively to the lever arm causes a twisting movement that causes the lever arm  8018  to move generally downwards. The movement is effectively a pivoting or hinging motion. However, the absence of a true pivot point means that the rotation is about a pivot region defined by bending of the passive beams  806 .  
         [0092]     The downward movement (and slight rotation) of the lever arm  8018  is amplified by the distance of the nozzle wall  8033  from the passive beams  806 . The downward movement of the nozzle walls and roof causes a pressure increase within the chamber  8029 , causing the meniscus to bulge as shown in  FIG. 11 . It will be noted that the surface tension of the ink means the fluid seal  8011  is stretched by this motion without allowing ink to leak out.  
         [0093]     As shown in  FIG. 12 , at the appropriate time, the drive current is stopped and the actuator beam  807  quickly cools and contracts. The contraction causes the lever arm to commence its return to the quiescent position, which in turn causes a reduction in pressure in the chamber  8029 . The interplay of the momentum of the bulging ink and its inherent surface tension, and the negative pressure caused by the upward movement of the nozzle chamber  8029  causes thinning, and ultimately snapping, of the bulging meniscus to define an ink drop  802  that continues upwards until it contacts adjacent print media.  
         [0094]     Immediately after the drop  802  detaches, meniscus  803  forms the concave shape shown in  FIG. 12 . Surface tension causes the pressure in the chamber  8029  to remain relatively low until ink has been sucked upwards through the inlet  8014 , which returns the nozzle arrangement and the ink to the quiescent situation shown in  FIG. 10 .  
         [0095]     As best shown in  FIG. 13 , the nozzle arrangement also incorporates a test mechanism that can be used both post-manufacture and periodically after the printhead is installed. The test mechanism includes a pair of contacts  8020  that are connected to test circuitry (not shown). A bridging contact  8019  is provided on a finger  8080  that extends from the lever arm  8018 . Because the bridging contact  8019  is on the opposite side of the passive beams  806 , actuation of the nozzle causes the priding contact to move upwardly, into contact with the contacts  8020 . Test circuitry can be used to confirm that actuation causes this closing of the circuit formed by the contacts  8019  and  8020 . If the circuit closed appropriately, it can generally be assumed that the nozzle is operative.  
         [0000]     Cradle  
         [0096]      FIG. 20  is a functional block diagram of printer cradle  4 . The printer cradle is built around a controller board  82  that includes one or more custom Small Office Home Office Printer Engine Chips (SOPEC) whose architecture will be described in detail shortly. Controller board  82  is coupled to a USB port  130  for connection to an external computational device such as a personal computer or digital camera containing digital files for printing. Controller board  82  also monitors:  
         [0097]     a paper sensor  192 , which detects the presence of print media;  
         [0098]     a printer cartridge chip interface  84 , which in use couples to printer cartridge QA chip  57  (see  FIG. 6 );  
         [0099]     an ink refill cartridge QA chip contact  132 , which in use couples to an ink refill cartridge QA chip (visible as item  176  in  FIG. 37 ); and  
         [0100]     rotor element angle sensor  149 , which detects the orientation of rotor element  60  (see  FIG. 6 ).  
         [0101]     In use the controller board processes the data received from USB port  130  and from the various sensors described above and in response drives a motor  110 , tricolor indicator LED  135  and, via interface  84 , printhead chip  52  (see  FIG. 6 ). As will be explained in more detail later, motor  110  is mechanically coupled to drive a number of mechanisms that provide auxiliary services to print cartridge  6  (see  FIG. 6 ). The driven mechanisms include:  
         [0102]     a rotor element drive assembly  145 , for operating rotor element  60  (see  FIG. 6 );  
         [0103]     a print media transport assembly  93 , which passes print media across printhead chip  52  during printing; and  
         [0104]     an air compressor  122  which provides compressed air to keep printhead chip  52  (see  FIG. 6 ) clear of debris.  
         [0105]     As will be explained in more detail shortly, motor  110  is coupled to each of the above mechanisms by a transmission assembly which includes a direct drive coupling from the motor spindle to an impeller of the air compressor and a worm-gear and cog transmission to the rotor element and print media transport assembly.  
         [0106]     The structure of cradle  4  will now be explained with reference to FIGS.  21  to  31 . As most clearly seen in the exploded view of  FIG. 26 , cradle  4  has a body shaped to complement cartridge  6  so that when mated together they form an inkjet printer. The cradle body is formed of base molding  90  and cradle molding  80 . The base molding acts as a support base for the cradle and also locates drive motor  110 , rotor element roller  94  and drive roller  96 . The base molding is snap fastened to cradle molding  80  by means of a number of corresponding flanges  120  and slots  123 . Cradle molding  80  defines an elongate recess  89  dimensioned to locate print cartridge  6 . A number of indentations in the form of slots  86  are formed in an internal wall of the cradle for receiving complementary protrusions in the form of ribs  78  ( FIG. 4 ) of cartridge  6 . Consequently cartridge  6  must be correctly orientated in order for it to be fully received into cradle molding  80 . Furthermore, the slots ensures that only those cartridges that are supported by the electronics of the cradle, and hence have non-interfering ribs, can be inserted into the cradle, thereby overcoming the problem of the drive electronics of the cradle attempting to drive cartridges having unsupported performance characteristics. Controller  82  is arranged to determine the performance characteristics of cartridges inserted into cradle  4  and to operate each cartridge in response to the determined performance characteristics. Consequently, it is possible for an inkjet cradle to be provided with a starter cartridge having relatively basic performance characteristics and then to upgrade as desired by replacing the starter cartridge with an improved performance upgrade cartridge. For example the upgrade cartridge may be capable of a higher print rate or support more inks than the starter cartridge.  
         [0107]     With reference to  FIG. 25 , drive shaft  127  of motor  110  terminates in a worm gear  129  that meshes with a cog  125 B that is, in turn, fixed to drive roller  96 . Referring again to  FIG. 26 , the drive roller is supported at either end by bearing mount assemblies  100 A and  100 B, which are in turn fixed into slots  101 A and  101 B of cradle mounting  80  (see also  FIG. 30 ). Similarly, rotor element translation roller  94  and pinch roller  98  are also supported by bearing mount assemblies  100 A and  100 B.  
         [0108]     Referring now to  FIG. 30 , opposite the motor end of drive roller  96  there is located a flipper gear assembly  140 . The flipper gear assembly consists of a housing  144  which holds an inner gear  142  and an outer gear  143  that mesh with each other. The inner gear is fixed and coaxial with drive roller  96  whereas housing  144  is free to rotate about drive roller  96 . In use the housing rotates with drive roller  96  taking with it outer gear  143  until it either abuts a stopper located on the cradle base molding  90  or outer gear  143  meshes with rotor element drive cog  146 . The direction of rotation of drive roller  96  is dependent on the sense of the driving current applied to motor  110  by control board  82  (see  FIG. 29 ). The meshing of outer gear  143  with rotor element drive cog  146  forms rotor element drive assembly  145  comprising drive roller  96 , inner gear  142 , outer gear  143  and rotor element drive cog  146 . Consequently, in this configuration power can be transmitted from drive roller  96  to rotor element drive roller  94 .  
         [0109]     With reference to  FIGS. 30 and 31 , the opposite ends of rotor element drive roller  94  terminate in cams  148 A and  148 B which are located in corresponding cam followers  150 A and  150 B. Cam followers  150 A and  150 B are ring shaped and pivotally secured at one side by pivot pins  152 A and  152 B respectively. Hinged jaws  154 A and  154 B are provided for clutching the rotor element slider blocks (items  66 A,  66 B of  FIG. 6 ) of the printer cartridge. The jaws are each pivotally connected to cam followers  150 A and  150 B opposite pins  152 A and  152 B respectively. Upon rotor element drive roller  94  being rotated, cams  148 A and  148 B abut the inner wall of cam followers  150 A and  150 B thereby causing the cam followers to rise taking with them jaws  154 A and  154 B respectively.  
         [0110]     In order to ensure that rotor element  60  is rotated through the correct angle, cradle  4  includes a rotor element sensor unit  156  ( FIG. 20 ) to detect the actual orientation of the rotor element. Sensor unit  156  consists of a light source and a detector unit which detects the presence of reflected light. Rotor element  60  has a reflective surface that is arranged to reflect rays from the light source so that the orientation of the rotor element can be detected by sensor  156 . In particular, by monitoring sensor unit  156 , controller board  82  is able to determine which face of rotor element  60  is adjacent printhead  52 .  
         [0111]     Apart from driving drive roller  96 , motor  110  also drives an air compressor  122  that includes a fan housing  112 , air filter  116  and impeller  114 . Fan housing  112  includes an air outlet  124  that is adapted to mate with air inlet port  76  ( FIG. 6 ) of cartridge  6   
         [0112]     A metal backplane  92  is secured to the rear of cradle molding  80  as may be best seen in side view in  FIG. 25  and in cross section in  FIG. 27 . Mounted to backplane  92  is a control board  82  loaded with various electronic circuitry. The control board is covered by a metal radio frequency interference (RFI) shield  102 . Control board  82  is electrically coupled to cradle connectors  84 A and  84 B via a flex PCB connector  106  and also to an external data and power connection point in the form of USB port connector  130 . USB connector  130  enables connection to an external personal computer or other computational device. Cradle connectors  84 A,  84 B are supported in slots formed at either end of cradle molding  80  and are arranged so that upon printer cartridge  6  being fully inserted into recess  89  of the cradle molding, cradle connectors  84 A and  84 B make electrical contact with cartridge connectors  58 A and  58 B (see  FIG. 6 ).  
         [0113]     Controller board  82  is connected by various cable looms and flexible PCB  106  to QA chip contact  132 . The QA chip contact is located in a recess  134  formed in cradle molding  80  and is situated so that during ink refilling it makes contact with a QA chip  176  located in an ink refill cartridge that will be described shortly.  
         [0114]     Controller board  82  also drives a tricolor indicator LED (item  135  of  FIG. 20 ) which is optically coupled to a lightpipe  136 . The lightpipe terminates in an indicator port  138  formed in cradle molding  80  so that light from the tricolor indicator LED may be viewed from outside the casing.  
         [0115]     Controller Board  
         [0116]     Printer units according to a preferred embodiment of the invention have a fundamental structure, namely a cradle assembly which contains all of the necessary electronics, power and paper handling requirements, and a cartridge unit that includes the highly specialised printhead and ink handling requirements of the system, such that it may be possible for a cradle unit to support a cartridge unit which enables different capabilities without the need to purchase a new cradle unit.  
         [0117]     In this regard, a range of cartridge units, each having a number of different features may be provided. For example, in a simple form it may be possible to provide a cartridge unit of three distinct types: 
        Starter Unit—15 ppm cartridge with 150 ml of ink capacity     Intermediate Unit—30 ppm cartridge with 300 ml of ink capacity     Professional Unit—60 ppm cartridge with +300 ml of ink storage capacity. 
 
 Such a system may be supported on one cradle unit with the user able to purchase different cartridge units depending upon their requirements and cost considerations. 
       
 
         [0121]     In the case of the professional unit, it may be required that a special cradle unit be provided that supports the more developed and refined functionality of such a cartridge unit. Cartridge units of different functionality may bear indicia such as color coded markings so that their compatibility with the cradle units can be easily identified.  
         [0122]     In this regard,  FIG. 32  shows the main PCB unit for a cradle unit operating at 15-30 ppm, whilst  FIG. 33  shows a main PCB unit for driving a cartridge unit operating at 60 ppm. As can be seen the PCBs are almost identical with the main difference being the presence of 2 SoPEC chips on the 60 ppm PCB. Hence, even if a user has purchased a cradle unit which may not initially support a more powerful cartridge unit, the present system structure makes it easy for the cradle unit to be easily upgraded to support such systems.  
         [0123]     The printer preferably also includes one or more system on a chip (SoC) components, as well as the print engine pipeline control application specific logic, configured to perform some or all of the functions described above in relation to the printing pipeline.  
         [0124]     Referring now to  FIG. 4 , from the highest point of view a SoPEC device consists of 3 distinct subsystems: a Central Processing Unit (CPU) subsystem  301 , a Dynamic Random Access Memory (DRAM) subsystem  302  and a Print Engine Pipeline (PEP) subsystem  303 .  
         [0125]     The CPU subsystem  301  includes a CPU  30  that controls and configures all aspects of the other subsystems. It provides general support for interfacing and synchronizing the external printer with the internal print engine. It also controls the low-speed communication to QA chips (which are described elsewhere in this specification). The CPU subsystem  301  also contains various peripherals to aid the CPU, such as General Purpose Input Output (GPIO, which includes motor control), an Interrupt Controller Unit (ICU), LSS Master and general timers. The Serial Communications Block (SCB) on the CPU subsystem provides a full speed USB1.1 interface to the host as well as an Inter SoPEC Interface (ISI) to other SoPEC devices (not shown).  
         [0126]     The DRAM subsystem  302  accepts requests from the CPU, Serial Communications Block (SCB) and blocks within the PEP subsystem. The DRAM subsystem  302 , and in particular the DRAM Interface Unit (DIU), arbitrates the various requests and determines which request should win access to the DRAM. The DIU arbitrates based on configured parameters, to allow sufficient access to DRAM for all requesters. The DIU also hides the implementation specifics of the DRAM such as page size, number of banks and refresh rates.  
         [0127]     The Print Engine Pipeline (PEP) subsystem  303  accepts compressed pages from DRAM and renders them to bi-level dots for a given print line destined for a printhead interface that communicates directly with up to 2 segments of a bi-lithic printhead. The first stage of the page expansion pipeline is the Contone Decoder Unit (CDU), Lossless Bi-level Decoder (LBD) and Tag Encoder (TE). The CDU expands the JPEG-compressed contone (typically CMYK) layers, the LBD expands the compressed bi-level layer (typically K), and the TE encodes Netpage tags for later rendering (typically in IR or K ink). The output from the first stage is a set of buffers: the Contone FIFO unit (CFU), the Spot FIFO Unit (SFU), and the Tag FIFO Unit (TFU). The CFU and SFU buffers are implemented in DRAM.  
         [0128]     The second stage is the Halftone Compositor Unit (HCU), which dithers the contone layer and composites position tags and the bi-level spot layer over the resulting bi-level dithered layer.  
         [0129]     A number of compositing options can be implemented, depending upon the printhead with which the SoPEC device is used. Up to 6 channels of bi-level data are produced from this stage, although not all channels may be present on the printhead. For example, the printhead may be CMY only, with K pushed into the CMY channels and IR ignored. Alternatively, the encoded tags may be printed in K if IR ink is not available (or for testing purposes).  
         [0130]     In the third stage, a Dead Nozzle Compensator (DNC) compensates for dead nozzles in the printhead by color redundancy and error diffusing of dead nozzle data into surrounding dots.  
         [0131]     The resultant bi-level 6 channel dot-data (typically CMYK, Infrared, Fixative) is buffered and written to a set of line buffers stored in DRAM via a Dotline Writer Unit (DWU).  
         [0132]     Finally, the dot-data is loaded back from DRAM, and passed to the printhead interface via a dot FIFO. The dot FIFO accepts data from a Line Loader Unit (LLU) at the system clock rate (pclk), while the PrintHead Interface (PHI) removes data from the FIFO and sends it to the printhead at a rate of ⅔ times the system clock rate.  
         [0133]     In the preferred form, the DRAM is 2.5 Mbytes in size, of which about 2 Mbytes are available for compressed page store data. A compressed page is received in two or more bands, with a number of bands stored in memory. As a band of the page is consumed by the PEP subsystem  303  for printing, a new band can be downloaded. The new band may be for the current page or the next page.  
         [0134]     Using banding it is possible to begin printing a page before the complete compressed page is downloaded, but care must be taken to ensure that data is always available for printing or a buffer under-run may occur.  
         [0135]     The embedded USB1.1 device accepts compressed page data and control commands from the host PC, and facilitates the data transfer to either the DRAM (or to another SoPEC device in multi-SoPEC systems, as described below).  
         [0136]     Multiple SoPEC devices can be used in alternative embodiments, and can perform different functions depending upon the particular implementation. For example, in some cases a SoPEC device can be used simply for its onboard DRAM, while another SoPEC device attends to the various decompression and formatting functions described above. This can reduce the chance of buffer under-run, which can happen in the event that the printer commences printing a page prior to all the data for that page being received and the rest of the data is not received in time. Adding an extra SoPEC device for its memory buffering capabilities doubles the amount of data that can be buffered, even if none of the other capabilities of the additional chip are utilized.  
         [0137]     Each SoPEC system can have several quality assurance (QA) devices designed to cooperate with each other to ensure the quality of the printer mechanics, the quality of the ink supply so the printhead nozzles will not be damaged during prints, and the quality of the software to ensure printheads and mechanics are not damaged.  
         [0138]     Normally, each printing SoPEC will have an associated printer QA, which stores information printer attributes such as maximum print speed. An ink cartridge for use with the system will also contain an ink QA chip, which stores cartridge information such as the amount of ink remaining. The printhead also has a QA chip, configured to act as a ROM (effectively as an EEPROM) that stores printhead-specific information such as dead nozzle mapping and printhead characteristics. The CPU in the SoPEC device can optionally load and run program code from a QA Chip that effectively acts as a serial EEPROM. Finally, the CPU in the SoPEC device runs a logical QA chip (ie, a software QA chip).  
         [0139]     Usually, all QA chips in the system are physically identical, with only the contents of flash memory differentiating one from the other.  
         [0140]     Each SoPEC device has two LSS system buses that can communicate with QA devices for system authentication and ink usage accounting. A large number of QA devices can be used per bus and their position in the system is unrestricted with the exception that printer QA and ink QA devices should be on separate LSS busses.  
         [0141]     In use, the logical QA communicates with the ink QA to determine remaining ink. The reply from the ink QA is authenticated with reference to the printer QA. The verification from the printer QA is itself authenticated by the logical QA, thereby indirectly adding an additional authentication level to the reply from the ink QA.  
         [0142]     Data passed between the QA chips, other than the printhead QA, is authenticated by way of digital signatures. In the preferred embodiment, HMAC-SHA1 authentication is used for data, and RSA is used for program code, although other schemes could be used instead.  
         [0143]     A single SoPEC device can control two bi-lithic printheads and up to six color channels. Six channels of colored ink are the expected maximum in a consumer SOHO, or office bi-lithic printing environment, and include:  
         [0144]     CMY (cyan, magenta, yellow), for regular color printing.  
         [0145]     K (black), for black text, line graphics and gray-scale printing.  
         [0146]     IR (infrared), for Netpage-enabled applications.  
         [0147]     F (fixative), to prevent smudging of prints thereby enabling printing at high speed.  
         [0148]     Because the bi-lithic printer is capable of printing so fast, a fixative may be required to enable the ink to dry before the page touches the page already printed. Otherwise ink may bleed between pages. In relatively low-speed printing environments the fixative may not be required.  
         [0149]     In the preferred form, the SoPEC device is color space agnostic. Although it can accept contone data as CMYX or RGBX, where X is an optional 4th channel, it also can accept contone data in any print color space. Additionally, SoPEC provides a mechanism for arbitrary mapping of input channels to output channels, including combining dots for ink optimization and generation of channels based on any number of other channels. However, inputs are typically CMYK for contone input, K for the bi-level input, and the optional Netpage tag dots are typically rendered to an infrared layer. A fixative channel is typically generated for fast printing applications.  
         [0150]     In the preferred form, the SoPEC device is also resolution agnostic. It merely provides a mapping between input resolutions and output resolutions by means of scale factors. The expected output resolution for the preferred embodiment is 1600 dpi, but SoPEC actually has no knowledge of the physical resolution of the Bi-lithic printhead.  
         [0151]     In the preferred form, the SoPEC device is page-length agnostic. Successive pages are typically split into bands and downloaded into the page store as each band of information is consumed.  
                                           Sub-   Unit               system   Acronym   Unit Name   Description                   DRAM   DIU   DRAM   Provides interface for DRAM               interface   read and write access for the               unit   various SoPEC units, CPU and                   the SCB block. The DIU provides                   arbitration between competing                   units and controls DRAM access.           DRAM   Embedded   20 Mbits of embedded DRAM.               DRAM       CPU   CPU   Central   CPU for system configuration               Processing   and control.               Unit           MMU   Memory   Limits access to certain memory               Management   address areas in CPU user mode.               Unit           RDU   Real-time   Facilitates the observation of               Debug Unit   the contents of most of the CPU                   addressable registers in SoPEC,                   in addition to some pseudo-                   registers in real time.           TIM   General   Contains watchdog and general               Timer   system timers.           LSS   Low Speed   Low level controller for inter-               Serial   facing with the QA chips               Interfaces           GPIO   General   General IO controller, with               Purpose   built-in Motor control unit,               IOs   LED pulse units and de-glitch                   circuitry           ROM   Boot ROM   16 KBytes of System Boot ROM                   code           ICU   Interrupt   General Purpose interrupt               Controller   controller with configurable               Unit   priority, and masking.           CPR   Clock,   Central Unit for controlling               Power   and generating the system               and Reset   clocks and resets and powerdown               block   mechanisms           PSS   Power Save   Storage retained while system               Storage   is powered down           USB   Universal   USB device controller for               Serial Bus   interfacing with the host USB.               Device           ISI   Inter-   ISI controller for data and               SoPEC   control communication with other               Interface   SoPECs in a multi-SoPEC system           SCB   Serial   Contains both the USB and ISI               Communi-   blocks.               cation               Block       Print   PCU   PEP   Provides external CPU with the       Engine       controller   means to read and write PEP       Pipe-           Unit registers, and read and       line           write DRAM in single 32-bit       (PEP)           chunks.           CDU   Contone   Expands JPEG compressed contone               Decoder   layer and writes decompressed               Unit   contone to DRAM           CFU   Contone   Provides line buffering between               FIFO   CDU and HCU               Unit           LBD   Lossless   Expands compressed bi-level               Bi-level   layer.               Decoder           SFU   Spot FIFO   Provides line buffering between               Unit   LBD and HCU           TE   Tag   Encodes tag data into line of               Encoder   tag dots.           TFU   Tag FIFO   Provides tag data storage               Unit   between TE and HCU           HCU   Halftoner   Dithers contone layer and               Compositor   composites the bi-level spot               Unit   and position tag dots.           DNC   Dead   Compensates for dead nozzles by               Nozzle   color redundancy and error               Compensator   diffusing dead nozzle data into                   surrounding dots.           DWU   Dotline   Writes out the 6 channels of               Writer   dot data for a given printline               Unit   to the line store DRAM           LLU   Line   Reads the expanded page image               Loader   from line store, formatting the               Unit   data appropriately for the bi-                   lithic printhead.           PHI   PrintHead   Responsible for sending dot               Interface   data to the bi-lithic print-                   heads and for providing line                   synchronization between multiple                   SoPECs. Also provides test                   interface to printhead such as                   temperature monitoring and Dead                   Nozzle Identification.                  
 
         [0152]     Ink Refill Cartridge  
         [0153]     As previously explained, printhead cartridge  6  includes an ink storage membrane  26  that contains internal ink reservoirs  28 - 34  that are connected to an ink refill port  8  formed in the top of cover molding  36 . In order to refill reservoirs  28 - 34  an ink dispenser in the form of an ink refill cartridge is provided as shown in FIGS.  35  to  42 . The structure of refill cartridge  160  will be explained primarily with reference to  FIG. 37  being an exploded view of the cartridge.  
         [0154]     Ink cartridge  160  has an outer molding  162  which acts as an operation handle or “plunger” and which contains an internal spring assembly  164 . Spring assembly  164  includes a platform  178  from which spring members  180  extend to abut the inside of cover molding  162 . The spring members bias platform  178  against a deformable ink membrane  166  that is typically made of polyethylene and contains a printing fluid, for example a colored ink or fixative. Ink membrane  166  is housed within a polyethylene base molding  170  that slides within outer molding  162 , as can be most readily seen in  FIGS. 38 and 39 . An ink outlet pipe  182  extends from membrane  166  and fits within an elastomeric collar  172  formed in the bottom of base molding  170 . A seal  174  covers collar  172  prior to use of the ink refill cartridge.  
         [0155]     At the bottom of base molding  170  there extends a lug  190 , which acts as a locating feature, shaped to mate with refill port of an inkjet printer component such as the ink refill port  8  of printer cartridge  6 . The position of outlet pipe  182  and collar  172  relative to lug  190  is varied depending on the type of printing fluid which the ink refill cartridge is intended to contain. Accordingly, a printing fluid system is provided comprising a number of printing fluid dispensers each having an outlet positioned relative to lug  190  depending upon the type of printing fluid contained within the dispenser. As a result, upon mating the refill cartridge to port  8 , outlet  192  mates with the appropriate inlet  42 A- 42 E and hence refills the particular storage reservoir  28 ,  30 ,  32 ,  34  dedicated to storing the same type of printing fluid.  
         [0156]     Extending from one side of the bottom of base molding  170  is a flange  184  to which an authentication means in the form of quality assurance (QA) chip  176  is mounted. Upon inserting ink cartridge  160  into ink refill port  8 , QA chip  176  is brought into contact with QA chip contact  132  located on cradle  4 .  
         [0157]     From the outside wall of base molding  170  there extends a retaining protrusion  168  that is received into an indentation being either pre-plunge recess  165  or post-plunge recess  169 , both of which are formed around the inner wall of top cover molding  162  as shown in  FIGS. 37 and 38 . Pre-plunge recess  165  is located close to the opening of the top-cover molding whereas post-plunge recess  169  is located further up the inner wall. When ink cartridge  160  is fully charged, retaining protrusion  168  is engaged by pre-plunge recess  165 . As will be more fully explained shortly, in order to overcome the engagement a deliberate plunging force, exceeding a predetermined threshold, must be applied to the top cover molding. Plunging discharges the ink through outlet  172 , and overcomes the bias of spring assembly  164  so that base molding  170  is urged into top cover molding  162  until retaining protrusion  168  is received into post-plunge recess  169 .  
         [0158]     Example of Use  
         [0159]     In use printer cartridge  6  is correctly aligned above cradle  4  as shown in  FIG. 3  and then inserted into recess  89  of upper cradle molding  80 . As the cartridge unit is inserted into cradle  4 , data and power contacts  84 A and  84 B on the cradle electrically connect with data and power contacts  58 A and  58 B of cartridge  6 . Simultaneously air nozzle  124  of air compressor assembly  122  penetrates air seal  44  and enters air inlet port  76  of cartridge  6 .  
         [0160]     As can be seen in  FIG. 27 , the inner walls of recess  89  form a seat or shelf upon which cartridge  6  rests after insertion. A number of resilient members in the form of springs  190  are provided to act against the cartridge as it is brought into position and also against the retainer catch, as it is locked over the cartridge. Consequently the springs act to absorb shocks during insertion and then to hold the cartridge fast with the cradle  4  and latch  7  by securely bias the cartridge in place against the latch. In an alternative the springs might instead be located on latch  7  in which case cartridge  6  would be biased against cradle  4 .  
         [0161]     Any attempt to insert the cartridge the wrong way around will fail due to the presence of orientating slots  86  and ribs  78  of cradle  4  and cartridge  6 . Similarly, a cartridge that is not intended for use with the cradle will not have ribs corresponding to orientating slots  86  and so will not be received irrespective of orientation. In particular, a cartridge that requires driving by a cradle having a twin SoPEC chip controller board will not have the correct rib configuration to be received by a cradle having a single SoPEC chip controller board.  
         [0162]     When the cartridge unit is first inserted into cradle unit  4 , and during transportation, rotor element  60  is orientated so that its capping face engages printhead  52  thereby sealing the nozzle apertures of the printhead. Similarly, when the printer unit is not in use the capping surface is also brought into contact with the bottom of printhead  52  in order to seal it. Sealing the printhead reduces evaporation of the ink solvent, which is usually water, and so reduces drying of the ink on the print nozzles while the printer is not in use.  
         [0163]     A remote computational device, such as a digital camera or personal computer, is connected to USB port  130  in order to provide power and print data signals to cradle  4 . In response to the provision of power, the processing circuitry of controller board  82  performs various initialization routines including: verifying the manufacturer codes stored in QA chip  57 ; checking the state of ink reservoirs  28 - 34  by means of the ink reservoir sensor  35 ; checking the state of rotor element  60  by means of sensor  156 ; checking by means of paper sensor  192  whether or not paper or other print media has been inserted into the cradle; and tricolor indicator LED  135  to externally indicate, via lightpipe  136 , the status of the unit.  
         [0164]     Prior to carrying out a printing operation a piece of paper, or other print media, must be introduced into cradle  4 . Upon receiving a signal to commence printing from the external computational device, controller board  82  checks for the presence of the paper by means of paper sensor  192 . If the paper is missing then tricolor LED  135  is set to indicate that attention is required and the controller does not attempt to commence printing. Alternatively, if paper sensor  192  indicates the presence of a print media then controller board  82  responds by rotating rotor element  60  to a predetermined position for printing.  
         [0165]     In this regard, upon detection of a printing mode of operation at start-up or during a maintenance routine, rotor element  60  is rotated so that its blotting face is located in the ink ejection path of printhead  52 . The blotting surface can then act as a type of spittoon to receive ink from the print nozzles, with the ink received ink being drawn into the body of rotor element  60  due to the absorbent nature of the material provided on the blotting surface. Since rotor element  60  is part of the printer cartridge  6 , the rotor element is replaced at the time of replacing the cartridge thereby ensuring that the blotting surface does not fill with ink and become messy.  
         [0166]     Subsequent to detecting a print command at USB port  130  and confirming the presence of print media, controller board  82  drives motor  110  so that drive roller  96  begins to rotate and, in cooperation with pinch roller  98 , draws the print media past printhead  52 . Simultaneously, controller board  82  processes print data from the external computational device in order to generate control signals for printhead  52 . The control signals are applied to the printhead via cradle interfaces  84 A,  84 B, carriage interfaces  58 A,  58 B and flex PCB contacts at either end of printhead chip  52 . Printhead chip  52  is bilithic, i.e. has two elongate chips that extend the length of the printhead, data is provided at either end of the printhead where it is transferred along the length of each chip to each individual nozzle. Power is provided to the individual nozzles of the printhead chips via the busbars that extend along the length of the chips. In response to received data and power, the individual nozzles of the printhead selectively eject ink onto the print media as it is drawn over the platen face of rotor element  60  thereby printing the image encoded in the data signal transmitted to USB port  130 .  
         [0167]     Operation of motor  110  causes air compressor  122  to direct air into the cartridge base molding. The air is channeled via fluid delivery paths in cartridge base molding  20  into the space behind air filter  51 . Upon the air pressure building up to a sufficient level to overcome the resistance of the air filter  51 , air is directed out through pores in air filter  51  along the length of the bottom of the cartridge base molding. The directed air is received between printhead chip  52  and air coverplate  54  whilst the printer is operating and is directed past the printhead chip surface, thereby serving to prevent degradation of the printhead by keeping it free of dust and debris.  
         [0168]     Referring now to  FIG. 40 , the first step of the ink refilling procedure is initiated by refill sensor  35  indicating to controller board  82  that there is a deficiency of printing fluid in storage reservoirs  28 ,  30 ,  32 ,  34 . In response to the signal from the ink cartridge QA chip that the ink is nearly depleted, controller board  82  activates indicator LED  138  to inform the user that another refill is necessary. Alternatively, the detection of whether there is a deficiency of printing ink might instead be calculated by the electronics of the controller board. As the volume of ink per nozzle injection is known and is consistent throughout the operation of the printhead (approximately 1 picolitre) the amount of ink delivered by the printhead can be calculated as well as the consumption of each color or type of ink. In this regard controller board  82  is able to monitor the consumption of each printing fluid and once this level has reached a predetermined level, the tricolor indicator LED can be asserted to indicate to a user that there is a need to replenish the printing fluids.  
         [0169]     Light from the indicator LED is transmitted by lightpipe  136  in order for an external indication to be presented to an operator of the printer at indicator port  138  of cradle  4 . This indication can convey to the user the color or type of ink that requires replenishing. The controller board can also send a signal via USB port  130  to the remote computational device to display to the user via the computational device the type of ink that requires replenishment.  
         [0170]     In order for the refilling procedure to proceed, printer cartridge  6  must be in place in printer cradle  4 . An ink refill cartridge  160  of the required type of ink is then brought into position over the ink refill port  8  that is situated on the upper surface of printer cartridge  6 . As previously described, ink refill port  8  includes a series of inlets  42 A- 42 E protected by a sealing film  40 . Beneath sealing film  40  there are located a number of printing fluid conduits  42 A- 42 E which provide direct access to ink storage reservoirs  28 ,  30 ,  32 ,  34 . An ink inlet is provided for each of the printing fluids, namely C, M, Y, K and Infrared and fixative where required. The position of the inlet for each of the different fluids is strategically placed laterally along inlet port  8  so that the ink outlet pin  182  of refill cartridge  160  automatically aligns and communicates with the particular one of inlets  42 A- 42 E for the specific printing fluid that cartridge  160  contains and which is to be is to be replenished.  
         [0171]     The second step of the ink refilling stage is shown in  FIG. 41 . In this figure, refill cartridge  160  has been docked into refill port  8  in the cartridge unit. Upon docking of refill cartridge  160  into refill port  8 , ink refill QA chip  176  automatically aligns with QA contact  132  on the cradle unit. Controller board  82  interrogates the various codes stored in QA chip  176  in order to verify the integrity and authenticity of ink refill cartridge  160 . If controller board  82  determines that QA chip  176  verifies the presence of authentic ink, namely from the appropriate manufacturer and of the required color or type, then it sets indicator LED  135  to show yellow, thereby indicating that refill cartridge  160  is accepted. Alternatively, controller board  82  may determine that an error state exists and in response set LED  135  to red in order to indicate that there is a problem with the refill cartridge. For example, an error state may be determined to exist if QA chip  176  failed to pass the verification step. Furthermore, it will often be the case that only one of reservoirs  28 ,  30 ,  32 ,  34  is in need of replenishment. For example, a reservoir that is assigned to store cyan colored ink may require refilling. In that case, should QA chip  176  indicates that ink refill cartridge  160  contains non-cyan ink then controller board  82  will set indicator LED  135  to red in order to flag an error state.  
         [0172]     It will be realized that in order for a QA assured refill to occur, communication between all parts of the printer unit is required. That is, printer cartridge  6  must be positioned in printer cradle  4  and ink refill cartridge  160  must be docked with cartridge  6  so that ink refill QA chip  176  is in contact with ink QA chip contact  132 . This ensures that each refilling action is controlled and reduces the potential for incorrect refilling which may damage the working of the printer.  
         [0173]     As shown in  FIG. 41 , when ink refill cartridge  160  is docked in refill port  8  of cartridge unit  6 , ink outlet pin  28  penetrates sealing film  40  and one of apertures  42 A- 42 E of the refill port to communicate with a corresponding one of ink inlets  24 . Ink inlet  24  is provided as an elastomeric molding so that penetration of ink seal  32 , which is located over ink refill cartridge outlet pin  28 , occurs automatically. As a consequence, self-sealing fluid communication is ensured between the ink stored in refill cartridge  160 , ink delivery conduits  43 A- 43 E and storage reservoirs  28 - 34 . The self-sealing fluid communication results in a pressurised fluid flow of ink into one of reservoirs  28 ,  30 ,  32 ,  34  occurring upon outer molding  162  being depressed.  
         [0174]     As shown in  FIG. 42 , the third stage of the ink refilling procedure occurs when top cover molding  162  is depressed thereby expelling the ink present within the ink refill cartridge  160  into one of printer cartridge reservoirs  28 - 34 . Following depressing of outer molding  162  it is apparent to an operator that the ink refill cartridge  160  has been spent and can therefore be removed from printer cartridge  6  as the refill stage is now complete. Upon completion of the refill stage refill sensor  35  generates a signal indicating that the printing fluid level in each of reservoirs  28 - 34  is greater than a predetermined level. In response to the signal from the refill sensor, controller board  82  sets indicator LED  135  to shine green thereby indicating to the operator that the refill process has been successfully completed.  
         [0175]     The force with which ink is expelled from ink refill cartridge  160  is determined by the degree of plunging force applied to the top cover molding  162  by an operator. Accordingly top cover molding  162  acts as an operation handle or plunger for the ink refill cartridge. Consequently it is possible that if the refilling step is not done carefully or done in haste, that the ink may be delivered to printer cartridge  6  at an unduly high pressure. Such a pressure could cause the ink stored within printer cartridge  6  to burst the ink storage membrane  26  and hence cause an ink spill within the cartridge unit that might irreparably damage the printer cartridge. The internal spring molding  164  prevents inadvertent bursting of the membrane by providing a safety mechanism against over pressurizing the ink being expelled from the refill unit. In this regard spring molding  164  is designed to limit the maximum force transmitted from the plunging of top cover molding  14  to deformable ink membrane  26 . Any force applied to top cover molding  14  which would cause ink to be expelled at a pressure above a maximum allowable level is taken up by spring molding  164  and stored within the spring members  180 . Spring molding  164  is suitably designed to prevent undue force being instantaneously applied to refill ink membrane  166 . That is, its deformation and/or elastic characteristics are selected so that it limits pressure in the membrane to a predetermined level.  
         [0176]     As shown most clearly in  FIGS. 38 and 39  a retaining protrusion  168  is located on the side of base molding  170 . Whilst ink cartridge  160  is in its pre-plunged state, retaining protrusion  168  mates with pre-plunge recess  165 . Engagement of protrusion  168  with the pre-plunge recess provides an additional measure of security during the refill process. This is because the engagement prevents unintended forces being applied from the top cover molding onto the internal ink membrane  166  and so prevents inadvertent plunging of the top cover during transport or delivery. Subsequent to docking of ink refill cartridge  160  with refill port  8 , top cover  162  is plunged with sufficient force to overcome the engagement of retaining protrusion  168  by pre-plunge recess  165 . Plunging top cover molding  162  causes platform  178  of the spring assembly  164  against ink membrane  166  thereby expelling the ink through outlet pipe  182  and into printer cartridge ink reservoir membrane  166 . In order to overcome the initial engagement of retaining protrusion  168 , an initial high force may have to be applied. Spring member  164  momentarily acts to protect ink membrane  166  from being over pressurized for this instance. Following the initial application of force normal plunging proceeds.  
         [0177]     As shown in  FIG. 38 , upon completion of the refilling step, retaining protrusion  168  comes into engagement with a locking feature in the form of post-plunge recess  169  which is located towards the top of the inside wall of ink cartridge outer molding  169 . Mating of retaining protrusion  168  with upper recess  169  locks ink cartridge outer molding  169  to base molding  170  subsequent to discharging of the ink. It will be realized that this arrangement overcomes the potential for a user to attempt to replenish ink refill cartridge  162  with an inferior ink which could cause damage to the nozzles of the printer cartridge as well as the ink refill cartridge. In its post-plunged configuration, the spent ink refill cartridge may be returned to a supplier. The supplier will be provided with a tool to unlock the refill cartridge and return the top cover to its upper position wherein authentic ink can be refilled into the refill unit for re-use and QA chip  176  reprogrammed to verify the authenticity of the ink.  
         [0178]     It will, of course, be realized that the above has been given only by way of illustrative example of the invention and that all such modifications and variations thereto, as would be apparent to persons skilled in the art are deemed to fall within the broad scope and ambit of the invention as defined by the following claims.  
         [0179]     While the present invention has been illustrated and described with reference to exemplary embodiments thereof, various modifications will be apparent to and might readily be made by those skilled in the art without departing from the scope and spirit of the present invention. Accordingly, it is not intended that the scope of the claims appended hereto be limited to the description as set forth herein, but, rather, that the claims be broadly construed.