Abstract:
Vapour removed from the drying chamber of a hardcopy apparatus is condensed and passed to a reservoir from which it is intermittently pumped into an ink supply cartridge. Cartridge supplies ink from a first bag via a first nozzle. As the first bag contracts, it allows a second bag to expand to receive the condensate from reservoir via a valving system and a second nozzle. In addition, a pump supplies air the second bag via piping; by switching over the valving system, it is the same pump which is used to transfer the condensate from reservoir to the cartridge.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to hardcopy apparatus, such as ink-jet printers, which consume ink. In particular it relates to an arrangement for removing the ink waste products, usually predominantly water, from the hardcopy apparatus.  
         BACKGROUND OF THE INVENTION  
         [0002]    The ink used in ink-jet printers comprises typically 20% by volume of pigment or dye with traces of various additives, some of which are volatile. The balance, i.e. substantially 80%, is water. When a swath of such ink is deposited on a print media it requires a drying time before the next swath is printed to avoid bleeding problems between the swaths. An end of plot drying time is also required to avoid ink becoming smeared during transfer of the print media to the next stage.  
           [0003]    To allow the ink to dry naturally takes a relative long time, which has an adverse effect on throughput, so inkjet printers and other hardcopy apparatus which are in heavy use are provided with active drying systems, which eliminate moisture content from the printed surface as quickly as possible. Typically the active drying system comprises a fan and ducting system to blow air over the ink in the print zone, and/or a heater arranged under the printing platen to evaporate the moisture.  
           [0004]    Since the vapour created by the drying system is predominantly water, the atmosphere in a room containing a hardcopy apparatus in heavy use can become unacceptably humid, with condensation forming on windows and walls. A large ink-jet printer can produce approximately 1 litre of water per hour.  
           [0005]    Accordingly, various methods have been proposed to prevent discharge of the water vapour to the environment. In one method, the vapour emerging from the printzone is condensed and conveyed outside of the hardcopy apparatus, for example to a nearby drain. This has the disadvantage of requiring an external hose connection and requires the apparatus to be located close to a local drain. Moreover, since the condensate will contain chemicals in the form of volatile constituents and unused ink, there may be environmental considerations which do not allow the condensate to be discharged in this way.  
           [0006]    In another method, the condensate is collected in a dedicated container within the hardcopy apparatus. This has the disadvantage of requiring within the apparatus additional space which needs to be readily accessible. In addition, time and effort are required to empty the container. The container also requires maintenance. Problems can also arise if the user or service engineer forgets to empty the container before it is full.  
         SUMMARY OF THE INVENTION  
         [0007]    Certain aspects of the present invention seek to overcome or reduce one or more of the above problems.  
           [0008]    According to a first aspect of the present invention there is provided a method of handling condensate from the printzone of hardcopy apparatus comprising the steps of supplying ink from one or more ink cartridges to said printzone, using said ink in a printing operation in said printzone, and, during part of said printing operation, feeding said condensate to said one or more ink cartridges and, during another part of said printing operation, feeding air to said one or more ink cartridges.  
           [0009]    Preferably the condensate is fed to the ink cartridge or one of the cartridges simultaneously with ink being extracted from the cartridge for printing. This provides at least part of the pressure needed to transfer the ink from the cartridge(s) to the printzone. Air is fed to the cartridge simultaneously with ink extraction. This is of assistance since the volume of the condensate is normally less than the volume of the ink removed.  
           [0010]    According to a second aspect of the present invention, there is provided a hardcopy apparatus employing ink from one or more ink cartridges and including a printzone where vapour is produced, means for condensing said vapour to produce a condensate and means for feeding said condensate to said one or more ink cartridges, wherein means are provided for supplying air to said one or more ink cartridges.  
           [0011]    The material collected in the condensing means may include droplets of ink which have not been vapourised, i.e. have remained in liquid form. The term “condensate” is to be understood as including such material.  
           [0012]    In addition, the hardcopy apparatus may have a service station including at least one spittoon for receiving ink from a respective print head in a print head servicing operation. The ink collected by the spittoon is waste ink, which may also be fed to the ink cartridges. The term “condensate” is further to be understood as including such waste ink.  
           [0013]    Preferably the air supply means is a pump and a valving arrangement is provided in a first switched configuration of which said pump supplies air to the cartridge and in a second switched configuration of which said pump causes condensate to be fed to the cartridge. This has the advantage that a single pump is used to transfer the air and condensate to the cartridge.  
           [0014]    According to a third aspect of the present invention, there is provided an ink cartridge for hardcopy apparatus, said cartridge having an interior and first and second nozzles, said interior comprising a bag and an interior region external to said bag, said first nozzle being in communication with the inside of the bag and said second nozzle being in communication with said interior region.  
           [0015]    An advantage of this arrangement is that use of the space within the cartridge is optimised. Another advantage is that used cartridges and their contents can be easily recycled. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    A preferred embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings, of which:  
         [0017]    [0017]FIG. 1 is a schematic side view of the print zone of an ink-jet printer in accordance with a first embodiment of the present invention;  
         [0018]    [0018]FIG. 2 is a schematic view of an ink supply and drying system for the printer of FIG. 1;  
         [0019]    [0019]FIGS. 3 and 4 are schematic views of respective modified ink cartridges for use in the system of FIG. 2;  
         [0020]    [0020]FIG. 5 is a schematic view of an ink-jet printer in accordance with a second embodiment of the present invention; and  
         [0021]    [0021]FIG. 6 is a schematic view, corresponding to part of FIG. 2, of an ink supply and drying system for the printer of FIG. 5. 
     
    
       [0022]    It will be appreciated that the drawings are intended for the purpose of explanation and are not to scale.  
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0023]    Referring to the drawings, FIG. 1 shows the print zone  10  of an ink-jet printer comprising a printhead  11  arranged to fire ink drops to deposit ink on a print media  12  travelling across a print platen  14 . As the media  12  moves from printzone  11  from left to right in FIG. 1 it enters a drying chamber  15 . Here the media  11  is subjected to heat produced by a heating lamp  16  arranged within chamber  15 . The relative humidity within the chamber  15  can exceed 90%. The chamber  15  thus contains an aerosol comprising both small ink droplets, which have been ejected but have not been deposited on the print media, and vapour (predominantly water) caused by evaporation from the drying ink. This aerosol is removed by an air ducting system comprising an air inlet  17  and an air outlet  18  which has an extractor fan  19 .  
         [0024]    The extracted vapour is then fed to a condenser  20 , FIG. 2, which produces a condensate of water contaminated with unused ink and volatile components. The condensate is passed to a reservoir  25 .  
         [0025]    [0025]FIG. 2 shows generally an ink supply system  100  for the print zone  10  of FIG. 1. Ink  31  for printhead  11  is supplied in a replaceable cartridge  30  comprising a rigid plastics container  33 . To prevent the access of air to the ink  31  it is held within container  33  inside an impermeable and collapsible plastics bag  32  having a mouth in communication with an outlet nozzle or port  34 . When printing occurs, a volumetric pump  35  is actuated to transfer ink  31  from bag  32  via nozzle  34  to printhead  11 .  
         [0026]    It is known with certain ink-jet cartridges, e.g. Hewlett-Packard types  80 ,  81  and  83 , to inject air into the container  33  to urge ink out of the bag  32 . The extraction of ink is controlled by the volumetric pump  35 , but the required pumping effort is reduced by the injection of air around the bag  32 . In the present embodiment, air is supplied from an air pump  40  via tubing  41 ,  42 ,  43  to an inlet nozzle  36  of the cartridge  30 . However, in the present embodiment, an intermediate valving arrangement  75  is additionally provided. In particular, air pump  40  is connected to the input of a two-way switching valve  50 . When the valve  50  is switched to a first outlet  51 , air is admitted to a first input  61  of a second switching valve  60 . The outlet of valve  60  is connected to an inlet nozzle or port  36  of the cartridge  30  which is connected to the mouth of a second impermeable and collapsible plastics bag  37  within container  33 .  
         [0027]    The ink-jet cartridge  30  is supplied when new with bag  32  full of ink  31  and occupying most of the volume within container  33 . At this stage, bag  37  is in a collapsed state and occupies only a small volume. As pump  35  extracts ink from the bag  32  it becomes smaller and pump  40  is operated to expand bag  37  to occupy the space which is now available. When cartridge  30  is finished, bag  32  is substantially empty of ink and in a collapsed state and bag  37  is substantially expanded state.  
         [0028]    In use, the prior art Hewlett-Packard cartridges were injected solely with air as the ink left its bag. In use of the present embodiment, condensate from the reservoir  25  is injected into the cartridge at certain times. Thus when valve  50  is switched to a second outlet  52  connected to reservoir  25 , condensate is pumped via a third switching valve  70  to a second input  62  of valve  60  and from there into bag  37 . The level of condensate in reservoir  25  is monitored so that it never becomes full and control means are provided so that valves  50 ,  60  operate in ganged manner. The printer has four printheads, and switching valve  70  has a plurality of further outlets  75 ′, which serve to share the condensate among the four ink-jet cartridges as they empty.  
         [0029]    In use, cartridge  30  is inserted into the printer. During printing operations, ink is extracted from nozzle  34  and air and condensate are pumped into nozzle  36 . After use, the spent cartridge  30  is removed.  
         [0030]    An advantage of the above-described arrangement is that no special operation is needed to remove the condensate. It is automatically removed simultaneously with the normal removal of a spent ink-jet cartridge, which is, of course, readily accessible. Only a small space is required for reservoir  25  and it does not need to be located in an accessible position. The arrangement is environmentally-friendly since no liquid effluent needs to be discharged via hosing and there are minimal vapour emissions from the print zone. A common pump  40  is used to transfer both air and condensate into the bag  37 .  
         [0031]    Various modifications may be made to the above-described arrangement. For example the air inlet  17  may be omitted in which case air enters solely at the bottom of the chamber  15 .  
         [0032]    Moreover, an additional print media drying and moisture extraction unit  85 , positioned before the print zone  11  in the media axis, may be provided with its own separate connection to the condensing circuit. In another modification, the ink in the printzone may be heated instead or in addition by a resistor  80  located underneath the media path. A hot air circulation system may be provided, with the air being heated remote from the printzone.  
         [0033]    If container  33  is sufficiently airtight, the bag  37  may be omitted as shown in the modified cartridge  130  of FIG. 3. In this case, the air and condensate occupy the interior of the container  33  not occupied by bag  32 .  
         [0034]    As shown in the modified cartridge  230  of FIG. 4, bag  32  may be omitted instead of bag  37 , in which case ink  31  occupies the remainder of the interior not occupied by bag  37 . Instead of a bag or bags, the regions within the interior of the cartridge may be separated by a flexible membrane. Initially, the ink is contained between one side of the membrane and part of the walls of the container  33 ; when the ink has been used up, air and condensate are contained between the other side of the membrane and the remaining part of the walls.  
         [0035]    For hardcopy apparatus with a single printhead, valve  70  may be omitted.  
         [0036]    Instead of pump  40 , a separate pump may be used to transfer condensate from the reservoir  25  into the cartridge  30 .  
         [0037]    Volumetric pump  35  may be omitted, in which case the injection of air or condensate by pump  40  into bag  37  is used to directly control the flow of ink  31  to printhead  11 .  
         [0038]    With a suitable control arrangement, reservoir  25  may be omitted and the outlet tube from condenser  20  may be connected directly to the valving arrangement  75 . Furthermore the valving arrangement  75  may be omitted, in which case the output from condenser  20  may pass straight through into bag  37 , additional air being pumped in as necessary. The output from condenser  20  may reach the bag solely under the forces of gravity, but a pumped arrangement is preferred, especially when the cartridge still contains a large amount of ink and considerable pressure is required.  
         [0039]    In another modification, an ink cartridge is employed with only one nozzle. In this case, condensate is collected in reservoir  25  until the ink bag in the cartridge is substantially empty of ink. Before removal of the cartridge, the condenser is connected to the nozzle by means of a suitable valving arrangement and the condensate is transferred into the ink bag. A suitable operating arrangement may be provided having a button which is actuated to initiate an ink cartridge replacement procedure. Before allowing access to the ink cartridge, the operation arrangement may effect the condensate transfer process automatically.  
         [0040]    In a printer  500  in accordance with a second embodiment of the present invention, FIGS. 5 and 6, printheads e.g.  11  are mounted on a carriage  510  which moves in both directions along a scanning axis indicated by a double-headed arrow  550 . At one end of the scanning axis there is provided a printhead service station  520 , which performs servicing operations on the printheads  11 . One of the operations comprises “spitting”, in which a small volume of ink is ejected from printhead  11  into a receptacle  521  in the service station  520 . The receptable for receiving the ink is known as a “spittoon”. To avoid the problem of waste ink collecting in spittoon  521 , a fluid outlet connection  522  is proivided which connects spittoon  521  to reservoir  25 . Thus waste ink from spittoon  521  is transferred with condensate from condenser  20  back to the ink cartridges  33 .  
         [0041]    In a modification, ink from spittoon  521  is instead connected via a fluid connection  523 , indicated in a broken line in FIG. 6, to the outlet of reservoir  25 .  
         [0042]    The above described arrangements may be used in other forms of hardcopy apparatus including plotters, scanners, photocopiers and facsimile machines.  
         [0043]    What has been described and illustrated herein is a preferred embodiment of the invention along with some of its variations. The terms, descriptions and figures used herein are set forth by way of illustration only and are not meant a&#39;s limitations. Those skilled in the art will recognise that many variations are possible within the spirit and scope of the invention, which is intended to be defined by the following claims and their equivalents in which all terms are meant in their broadest reasonable sense unless otherwise indicated.