Abstract:
The invention relates to a service station for an inkjet printer. The service station includes at least one cap for capping an inkjet nozzle which is mounted on an inkjet carriage of the inkjet printer. The service station also includes at least one wiper arranged to wipe said nozzle of the inkjet carriage. The wiper is arranged to move towards and away from the inkjet nozzle in response to movement of the inkjet carriage so as to enable the nozzle to be wiped of any residual ink.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to a service station in an inkjet printer, and to an inkjet printer incorporating such a service station.  
         BACKGROUND OF THE INVENTION  
         [0002]    The service station of an inkjet printer includes an apparatus for wiping and capping the nozzles of an inkjet cartridge. The wipers are arranged to wipe the residual ink from the cartridge nozzles after completion of printing. The wiping and capping operations of the service station prevent the nozzles from becoming blocked and thereby extend the life of the inkjet cartridge.  
           [0003]    U.S. Pat. No.  5 , 627 , 574  describes a maintenance device in an inkjet printing apparatus. The maintenance device includes a fixed wiper which is used to wipe residual ink from the inkjet nozzle. However, as the wiper is fixed it is always in contact with the nozzle of the inkjet cartridge as the printing carriage enters and leaves the maintenance device. Accordingly, the arrangement of U.S. Pat. No. 5,627,574 is such that the wiper may cause cross contamination of ink in a multiple inkjet nozzle system. This is because the wiper would wipe over both of the nozzles of the inkjet cartridge and therefore any residual ink from one cartridge nozzle would be deposited on the other cartridge nozzle. This greatly impacts on the performance of the inkjet printer. The present invention seeks to address this problem.  
         SUMMARY OF THE INVENTION  
         [0004]    According to a first aspect of the present invention there is provided a service station for an inkjet printer, said service station including at least one cap for capping an inkjet nozzle which is mounted on an inkjet carriage of said inkjet printer, and at least one wiper arranged to wipe the inkjet nozzle of the inkjet carriage and wherein the wiper is arranged to move towards and away from said inkjet nozzle in response to movement of the inkjet carriage.  
           [0005]    Preferably, said service station includes first and second caps for capping respective first and second inkjet nozzles. The service station preferably includes first and second wipers arranged to wipe said respective first and second nozzles.  
           [0006]    In a preferred form of the invention, the service station includes a main frame arranged to be mounted to a chassis of the inkjet printer, a cap frame on which said first and second caps are mounted and a wiper frame on which said first and second wipers are mounted. The cap frame and wiper frame are connected to said main frame in a manner whereby movement of the cap frame results in the movement of said wiper frame to an in-use position in which said first and second wipers can wipe their respective inkjet nozzles. The wiper frame is preferably arranged to move between a lower or out of use position to an upper or in-use position.  
           [0007]    In a preferred form, the cap frame can move both horizontally and vertically relative to said main frame to achieve capping of said first and second inkjet nozzles. Vertical movement of said cap frame also preferably results in a vertical movement of said wiper frame to said in-use position. Vertical movement of said wiper frame causes said first and second wipers to move from a lower position in which they do not contact their respective inkjet nozzles to said upper position in which the inkjet nozzles are wiped by their respective wipers.  
           [0008]    The service station preferably includes means to lock the wiper frame in the upper position. The lock means preferably includes a spring biased wiper hook which is arranged to be hingedly connected to the wiper frame. The bias for the wiper hook is preferably provided by a spring connection between a portion of the wiper hook and a portion of the wiper frame.  
           [0009]    Release means is preferably provided to release the locking means so that the wiper frame can move from the upper position to the lower position. The release means is preferably activated by the inkjet carriage contacting a release member mounted on the main frame. The release member is preferably an activation arm pivotally mounted on the main frame. The activation arm preferably has a free end arranged to contact said wiper hook when the activation arm is caused to pivot downwardly. Contact of the free end of the activation arm on the wiper hook causes the spring biased wiper hook to disengage from an engagement member on the main frame and to move under the action of the spring bias to the lower position.  
           [0010]    A biasing means, preferably in the form of a leaf spring, is located between the main frame and the wiper frame. The leaf spring serving to bias the wiper frame away from the main frame and into the lower position.  
           [0011]    Preferably, a blotter is arranged to be mounted on the cap frame so that any ink wiped from the nozzles by the wipers is collected by the blotter.  
           [0012]    The caps are preferably located on a cap mount which snap fits to the cap frame.  
           [0013]    The wipers preferably snap fit onto respective wiper mounts which are integrally formed with the wiper frame.  
           [0014]    The cap frame is preferably connected to the chassis or the main frame by a tension spring. The tension spring serving to return the cap frame from a position in which the caps cover their respective nozzles to a clear position in which the caps do not cover their respective nozzles.  
           [0015]    The service station is preferably arranged to be used in an inkjet printer having an inkjet carriage mounted on a shaft. The service station is mounted on a chassis of the printer such that the inkjet carriage can be driven along the shaft and over the service station so as to enable the inkjet carriage to contact a portion of the cap frame. Contact between the inkjet carriage and the portion of the cap frame causes the cap frame to move with the inkjet carriage to a home position. The cap frame is mounted on the main frame in such a manner that contact between the cap frame and the inkjet carriage cause both a substantially horizontal and a substantially vertical change in the positioning of the cap frame relative to the main frame. To this end, the cap frame preferably includes at least one pin extending therefrom which is arranged to be located in a ramp formed in the main frame. Movement of the cap frame due to contact by the inkjet carriage causes the cap frame to move along and up the ramp thereby changing the vertical positioning of the cap frame relative to the chassis as well as its horizontal positioning.  
           [0016]    Preferably, the cap frame has two pairs of opposed pins extending therefrom. The pins being arranged to extend from the sides of the cap frame and to move in respective ramps formed in the main frame.  
           [0017]    The wiper frame preferably includes at least one pin extending therefrom and arranged to be located within a groove formed in the main frame. The wiper frame pin is preferably arranged to move upwardly in the groove in the main frame as a result of the end of the pin engaging in an aperture formed in the cap frame. Accordingly, said substantially vertical movement of said cap frame during movement of the inkjet carriage to the home position causes said pin of said wiper frame to move upwardly within the groove formed in the main frame.  
           [0018]    Preferably, the wiper frame includes two pairs of opposed pins mounted on the sides of the wiper frame, each pin being arranged to be received in a respective groove formed in the main frame. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]    An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:  
         [0020]    [0020]FIG. 1 is a perspective view of an inkjet printer showing a service station in accordance with an embodiment of the invention. FIG. 2 is a perspective view of the service station shown in FIG. 1. FIG. 3 is an assembly view of the components of the service station shown in FIG. 2. FIG. 4 is a front view showing the inkjet carriage over the service station and the caps capping the nozzles of the inkjet carriage. FIG. 5 is a front view showing the inkjet carriage moving away from the service station.  
         [0021]    [0021]FIG. 6 is a front view showing the wiper hook of the service station in the upper position. FIG. 7 is a front view similar to that shown in FIG. 6 but with the wiper hook in the lower position. FIG. 8 is a front view showing the wipers in the upper position wiping the nozzles of the inkjet cartridge. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0022]    [0022]FIG. 1 illustrates an inkjet printer  10  having a chassis  12 , an inkjet carriage  14 , a shaft  16  and a service station  18 . The inkjet carriage  14  is arranged to be driven along the shaft by a motor. The components of the inkjet printer  10  other than the components of the service station  18  are standard within the art.  
         [0023]    The inkjet carriage  14  carries a pair of inkjet nozzles  20 . When the inkjet printer  10  is not in use, the inkjet carriage  14  is driven along the shaft  16  until it is located above the service station  18 . The carriage  14  is located above the service station  18  so that the nozzles  20  can be capped by respective caps  22  which are located in the service station  18 .  
         [0024]    The components of the service station  18  are best illustrated in FIGS. 2 and 3. As shown in FIG. 3, the service station  18  includes a main frame  30  which is arranged to be mounted to the chassis  12  by a pair of screws (not shown). The service station  18  also includes a cap frame  32  on which the pair of caps  22  are arranged to be mounted and a wiper frame  34  on which a pair of wipers  36  are arranged to be mounted. As will be explained in more detail subsequently, the cap frame  32  and the wiper frame  34  are mounted on the main frame  30  in such a manner that when the inkjet carriage  14  moves into a position above the service station  18  and thereby contacts a portion of the cap frame  32 , the cap frame  32  is caused to move in a direction substantially parallel to the longitudinal axis of the shaft  16 . In addition to this substantially horizontal movement and during the same operational time, the cap frame  32  is caused to move substantially vertically. In other words, contact between the inkjet carriage  14  and cap frame  32  results in a change in both the horizontal and vertical positioning of the cap frame  32 . The inkjet carriage  14  and cap frame  32  will continue to move substantially horizontally until the leading end  14   a  of the inkjet carriage  14  reaches a home position wherein it strikes the end wall  12   a  of the chassis  12 .  
         [0025]    Movement of the cap frame  32  causes the wiper frame  34  to also move substantially vertically. This results in the wipers  36  moving from a lower position where they are well clear of the nozzles  20  to an upper position in which they can contact the nozzles  20  of the inkjet carriage  14 . The wiper frame  34  is maintained in the upper position by means of a spring-loaded wiper hook  38 . The wipers  36  and attached wiper frame  34  are returned to the lower position when the inkjet carriage  14  is caused to contact an activation arm  40  mounted on the main frame  30 . This action will be described in more detail below.  
         [0026]    The main frame  30  is arranged to be connected to the chassis  12  of the inkjet printer  10  by means of four threaded connectors (not shown) which pass through the mounting points  42 . The main frame  30  also includes four ramps  44  which are formed in the side walls  45  of the main frame  30  and are configured to receive respective pins  46  located on the cap frame  32 . The ramps  44  are configured so that when the leading end  14   a  of the inkjet carriage  14  contacts the arm  32   a  of the cap frame  32 , the cap frame  32  is driven along the ramps  44  resulting in both a horizontal and vertical movement of the cap frame  32 . The cap frame  32  and inkjet carriage  14  will move along the shaft  16  until the inkjet carriage  14  reaches the home position.  
         [0027]    During the movement of the inkjet carriage  14  to the home position in accordance with a preferred embodiment of the invention, the cap frame  32  is caused to move approximately 8 mm horizontally and 3.8 mm vertically.  
         [0028]    The cap frame  32  is arranged to be located on the main frame  30  so that the pins  46  engage within their respective ramps  44 . The cap frame  32  also includes side plates  48  which extend downwardly from the body  32   b  of the cap frame  32 . Each side plate  48  includes a pair of substantially rectangular shaped apertures  52  which are arranged so that they can receive the respective pins  54  which extend outwardly from the side walls  34   a  of the wiper frame  34 . This arrangement of the pins  54  within the apertures  52  is such that when the cap frame  32  moves vertically as a consequence of its contact with the inkjet carriage  14 , the pins  54  of the wiper frame  34  are captured within the apertures  52  thereby causing the wiper frame  34  to be moved vertically. The movement of the wiper frame  34  is substantially vertical due to the engagement of the body of the pins  54  within respective elongate grooves  56  formed in the side walls  45  of the main frame  30 .  
         [0029]    The caps  22  are arranged to be located on cap mounts  23  which snap fit onto the cap frame  32 . A blotter  59  to blot any ink stemming from the wipers  36  is also mounted on the cap frame  32 .  
         [0030]    Extending substantially vertically above the wiper frame  34  are a pair of wiper mounts  69 . Each of the wiper mounts are arranged to receive a wiper  36 . Each wiper  36  is preferably snap-fitted onto its respective wiper mount  69 . The wiper frame  34  is configured so that it can be located within the body of the main frame  30  and so that the pins  54  extend through their respective vertical grooves  56  formed in the main frame  30  and through the apertures  52  formed in the side plates  48  of the cap frame  32 .  
         [0031]    A leaf spring  62  is sandwiched between the main frame  30  and the wiper frame  34  and tends to push the wiper frame  34  downwardly so as to locate the wipers  36  in the lower position. As stated previously, the wiper hook  38  is provided to lock the wiper frame  34  in the upper position. The wiper hook  38  is configured so that it can be hingedly mounted to the wiper frame  34  by virtue of a hinge pin  64  on the wiper hook  38 . Hinge pin  64  is arranged to be located in a pair of opposed seats  66  formed in the wiper frame  34 . When the wiper hook  38  is connected to the wiper frame  34  a spring  67  (as shown in FIGS. 6 and 7) is connected between spring connection point  68  on the wiper hook  38  and connection point  70  on the wiper frame  34 . The positioning of the pin  64 , seats  66  and connection points  68 ,  70  are such that when the wiper frame  34  is in the upper position the spring  67  tends to rotate the wiper hook  38  in a clockwise direction. This rotation of the wiper hook  38  causes a locking groove  72  formed in the wiper hook  38  to engage about a protrusion  73  formed on the main frame  30 . This is best illustrated in FIG. 6. In this manner the wiper frame  34  and attached wipers  36  are maintained in the upper position.  
         [0032]    Mounted on the main frame  30  by means of a hinge pin  80  is the activation arm  40 . The activation arm  40  is arranged to pivot about the hinge pin  80  until a portion of the activation arm  40   a  contacts against a stop  82  formed on the main frame  30 . When the activation arm  40  is caused to pivot due to contact by the inkjet carriage  14 , a pin  40   b  formed on the free end of the activation arm  40  is caused to contact against a slant face  84  formed on the wiper hook  38 . This contact is sufficient to release the protrusion  73  formed on the main frame  30  from the locking groove  72 . Accordingly, the wiper frame  39  under the action of the leaf spring  62  can be returned to the lower position. This movement of the wiper hook  38  is best illustrated in FIG. 7. The downwardly projecting arrow in FIG. 7 represents the pressure applied to the activation arm  40  by the underside of the inkjet carriage  14 . The portion  100  of the inkjet carriage  14  which contacts the activation arm  40   a  is shown in FIG. 8.  
         [0033]    In accordance with a preferred embodiment of the invention, the inkjet carriage  14  is required to move 22.5 mm along the shaft  16  and away from the home position before it contacts the activation arm  40 . This means that when the wiper frame  34  is located in the upper position, the inkjet carriage  14  can move back and forth along the shaft  16  so as to cause the nozzles  20  to wipe over their respective wipers  36  provided the inkjet carriage  14  does not move greater than 22.5 mm away from the home position. Once the carriage  14  moves a distance greater than 22.5 mm from the home position contact of the inkjet carriage  14  with the activation arm  40  will cause the wipers  36  to be moved to their lower position. The back and forth motion of the inkjet carriage  14  to wipe the nozzles  20  is shown schematically in FIG. 8.  
         [0034]    As will be readily appreciated from FIG. 4, the caps  22  are mounted on the cap frame  32  so that when the cap frame  32  is caused to moved vertically upward by virtue of the contact between the arm  32   a  and the inkjet carriage  14 , the caps  22  are caused to raise and to engage against the underside of the nozzles  20 . The wiper hook  38  maintains the wiper frame  34  in the upper position, while the action of the carriage  14  pushing against the cap frame  32  provides sufficient capping force to the caps  22  to ensure a proper seal between them and the end of the nozzles  20 .  
         [0035]    It will be appreciated from the discussion above that the wipers  36  are maintained in their lower position until they are required to wipe the end of the nozzles  20 . The nozzles are only raised to the upper position when the inkjet carriage  14  is positioned relative to the service station  18  so that each respective wiper  36  can only wipe against its respective nozzle  20 . To explain this in more detail, it should be appreciated that typically the inkjet carriage  14  would carry a first nozzle  20  for black ink and a second nozzle  20  for coloured ink. Similarly, the wiper frame  34  would carry a first wiper  36  which is arranged to wipe the first nozzle and second wiper  36  which is arranged to wipe the second nozzle  20 . The arrangement of the ramps  44  in the main frame  30  is such that movement of the cap frame  32  is controlled so that the wiper frame  34  is timely raised so that it reaches the upper position once the first nozzle (the rightmost nozzle as viewed in FIG. 8) has passed above the leftmost wiper on the wiper frame  34 . This ensures that there is no cross contamination of the inks as a consequence of any contact between the wipers  36  and nozzles  20 .  
         [0036]    It will also be appreciated by those skilled in the art that the previously described arrangement is simple in its construction and that it does not require a secondary motor to drive the service station  18 . Any movement of the components of the service station  18  is a consequence of contact with the inkjet carriage  14  as it is driven by a primary motor (not shown) along the shaft  16 .  
         [0037]    While the embodiments described herein are preferred, it will be appreciated from the specification that various alternatives, modifications, variations or improvements therein may be made by those skilled in the art are within the scope of the invention, which is defined by the claims.