Abstract:
A printer is disclosed. The printer includes an ink jet print head having a plurality of nozzles to mark a printable recording medium with ink and an ink system to provide ink to the nozzles. The ink system includes a print head capping system to cap the nozzles whenever the nozzles are not in use and a hydration system to supply a hydration fluid to the print head capping system to provide moisture to the ink at the nozzles while the nozzles are capped.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates generally to the field of ink jet printing systems. More particularly, the invention relates to maintaining a print engine within an ink jet printing system. 
       BACKGROUND 
       [0002]    An ink jet printer is an example of a printing apparatus that ejects droplets of ink onto a recording medium, such as a sheet of paper, for printing an image on the recording medium. The ink jet printer includes a print engine having one or more ink jet print heads provided with an ink cartridge that accommodates the ink. In operation of the print engine the ink is supplied from the ink cartridge to ejection nozzles of each print head so that a printing operation is performed by ejection of the ink droplets from selected ejection nozzles. 
         [0003]    Whenever an ink jet printer remains idle for a duration after printing, print heads may lose water within the ink through the ejection nozzles as the water is absorbed within the capping system, lost to the ambient air, or absorbed within ink that has become less hydrated. As water is lost from the ink, the viscosity may increase, and/or the ink suspension may become unstable, resulting in jetouts. Jetouts typically result in poor image formation quality and require up to several hours of print head maintenance to recover functionality. 
         [0004]    In ink jet printers implementing Magnetic Ink Character Recognition (MICR) inks, the MICR particles may settle in, and clog, the print head caps and ambient lines. In either event, service personnel are required to spend additional time manually hydrating the print heads or cleaning jetouts. 
         [0005]    Therefore, a print head hydration system is desired. 
       SUMMARY 
       [0006]    In one embodiment, a printer is disclosed. The printer includes an ink jet print head having a plurality of nozzles to mark a printable recording medium with ink and an ink system to provide ink to the nozzles. The ink system includes a print head capping system to cap the nozzles whenever the nozzles are not in use and a hydration system to supply a hydration fluid to the print head capping system to provide moisture to the ink at the nozzles while the nozzles are capped. 
         [0007]    In another embodiment, a method is disclosed. The method includes monitoring a fluid detection system within an inkjet printer, determining when hydration fluid may be provided to a print head capping system and supplying a hydration fluid from a hydration system to the capping system to provide moisture to ink at print head nozzles while the nozzles are capped. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    A better understanding of the present invention can be obtained from the following detailed description in conjunction with the following drawings, in which: 
           [0009]      FIG. 1  illustrates one embodiment of a printing system; 
           [0010]      FIG. 2  illustrates one embodiment of a print engine; and 
           [0011]      FIG. 3  illustrates another embodiment of a print engine; and 
           [0012]      FIGS. 4A-4C  are flow diagrams illustrating embodiments of operation for a print head hydration system. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    A print head hydration system is described. In the following description, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without some of these specific details. In other instances, well-known structures and devices are shown in block diagram form to avoid obscuring the underlying principles of the present invention. 
         [0014]    Reference in the specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment. 
         [0015]      FIG. 1  illustrates one embodiment of a printing system  100 . Printing system  100  includes a print application  110 , a server  120  and a printer  130 . Print application  110  makes a request for the printing of a document. Print server  120  processes pages of output that mix all of the elements normally found in presentation documents, e.g., text in typographic fonts, electronic forms, graphics, image, lines, boxes, and bar codes. 
         [0016]    Print server  120  subsequently communicates with printer  130 . Printer  130  includes a control unit  140  and a print engine  160 . Control unit  150  receives print jobs into printer  130 . Further, control unit  150  processes and renders objects received from print server  120  and provides sheet maps for printing to print engine  160 . Moreover, control unit  150  may include processing logic that may include hardware (e.g., circuitry, dedicated logic, programmable logic, microcode, etc.), software (such as instructions run on a processing device), or a combination thereof. 
         [0017]    Print engine  160  includes print heads  165 , which provide an imaging process to mark a printable recording medium (e.g., paper). In one embodiment, print heads  165  includes forty print heads, each having fourteen hundred nozzles. However, other embodiments of print engine  160  may be implemented. Further, print engine  160  includes an ink system that provides ink to print heads  165 . 
         [0018]      FIG. 2  illustrates one embodiment of a print engine ink system  200 , which includes a print head capping and maintenance system  220  and a hydration system  250 . Print head capping and maintenance system  220  includes a cap  222 , vacuum manifold  224  and ambient manifold  226 , which operate as a maintenance station for pulling ink through and from a print head during maintenance. 
         [0019]    Particularly, cap  222  is used to cover a print head  165  during idle or maintenance to prevent drying, and is uncapped during printing. Vacuum manifold  224  is coupled to a vacuum source via one or more hoses to pull ink from a print head  165 . Ambient manifold  226  is coupled to an air source that is used to relieve the vacuum prior to removing cap  222  in order to prevent damage to print heads  165 . 
         [0020]    Print head capping and maintenance system  220  also includes a pump coupled to vacuum manifold  224  via a solenoid to pump ink into a waste ink tank  228 . Waste ink tank  228  is also coupled to ambient manifold  226  via a separate solenoid. As discussed above, print heads  165  or caps  222  may lose water during printing, resulting in conditions that may lead to jetouts. 
         [0021]    According to one embodiment, hydration system  250  delivers a hydrating fluid (e.g., water) into print head capping and maintenance system  220  whenever it is determined that hydrating the print heads  165  is required. Hydration system  250  includes a controller  252 , a manifold  254  and a water tank  256 . Additionally, hydration system  250  includes sensors  251 ,  253  and  255 , pumps P 1  and P 2 , and solenoids S 1 -S 10 . 
         [0022]    In one embodiment, controller  252  controls the pumping of water from hydration system  250  into print head capping and maintenance system  220 . In such an embodiment, controller  252  activates/deactivates one or more solenoids, manifold  254  and pumps in response to input received from one of the sensors. For example, controller  252  activates solenoid S 1 , manifold  254  solenoids S 3 -S 10  and pump P 1  in order to pump water from tank  256  into a line coupled to vacuum manifold  224  upon sensor  257  providing a signal that the print head capping and maintenance system  220  moisture level is too low or a time limit has been reached. 
         [0023]    The above embodiment is implemented for pigment and dye print head  165  applications.  FIG. 3  illustrates another embodiment of print engine  160  in which hydration system  250  pumps water into a line coupled to ambient manifold  226  in order to perform MICR cleaning. 
         [0024]    According to one embodiment, hydration system  250  operates in one of three cycles: Start; Fill and Purge. The Start sequence is implemented to initialize hydration system  250  to ensure that conditions are adequate at print head capping and maintenance system  220  for hydration. In one embodiment, hydration may only occur when the printer has been printing for a predetermined length of time (e.g., 10 minutes). In a further embodiment, hydration is restricted to a length of time (e.g., once per twenty-four hour period). 
         [0025]      FIGS. 4A  is a flow diagram illustrating one embodiment of operation for a Start cycle performed at hydration system  250 . At decision block  402 , it is determined whether the print head  165  is in an away position. If so, a start timer within controller  252  is activated, processing block  404 . Otherwise control is returned to decision block  402  where it is again determined whether the print head  165  is in the away position. 
         [0026]    At decision block  406 , it is determined, by checking the start timer, whether the print head  165  has remained in the away position. If the print head  165  has not remained in the away position, hydration will not start. As a result, control is returned to decision block  402  where it is determined whether print heads  165  are in the away position. 
         [0027]    If the print head  165  has remained in the away position, it is determined whether the print head  165  has been in the away position for a predetermined period of time (e.g., ten minutes), decision block  408 . If not, control is returned to decision block  408 . If the predetermined period has expired since the print head  165  has been in the away position, it is determined whether the fluid level in tank  256  is low (e.g., sensor  253  is on), processing block  410 . In one embodiment, a warning message indicating low tank level is generated prior to returning control to decision block  402  upon a determination that the fluid level in tank  256  is low. 
         [0028]    Otherwise, it is determined whether the fluid at cap  222  is at a predetermined threshold level (e.g., sensor  257  is on), decision block  412 . If the fluid level is detected as being at the predetermined threshold level a warning message providing an indication to check sensor  257  is generated prior to returning control to decision block  402 . 
         [0029]    If cap  222  is not at the predetermined threshold level, it is determined whether twenty-four hours has elapsed since the previous Fill cycle has been completed, decision block  414 . If twenty-four hours has elapsed, the Fill cycle is performed, processing block  416 . If not, control is returned to decision block  402 . 
         [0030]      FIG. 4B  is a flow diagram illustrating one embodiment a Fill cycle performed at hydration system  250 . In one embodiment, the Fill cycle supplies fluid to print head capping and maintenance system  220  until sensor  257  detects that the fluid has reached the predetermined level or moisture threshold (e.g., has the water reached a fill limit, or has the humidity in cap reached an appropriate limit?). At processing block  422 , a fill timer at controller  252  is activated. 
         [0031]    At processing block  424 , controller  252  activates Pump P 1 , solenoid S 1  and the manifold  254  solenoids. At decision block  428 , it is determined whether the timer has timed out. If the timer has timed out, controller  252  deactivates Pump P 1 , solenoid S 1  and the manifold  254  solenoids, processing block  430 . At processing block  432 , hydration system  250  may enter the Purge cycle. Additionally, a warning message may be generated indicating the timeout. 
         [0032]    If the timer has not timed out, it is determined whether the print head  165  has remained in the away position, processing block  440 . If the print head  165  has not remained in the away position, control is returned to processing block  432  where hydration system  250  may enter the Purge cycle. Otherwise, a determination is made as to whether the fluid at cap  222  is at the predetermined threshold (e.g., sensor  257  is on), decision block  442 . 
         [0033]    If the hydration fluid is not detected as being at the predetermined threshold control is returned to decision block  428  for determination of a timeout. If cap  222  is at the predetermined threshold level, controller  252  deactivates Pump P 1 , solenoid S 1  and the manifold  254  solenoids, processing block  444 . At processing block  446 , the twenty-four hour timer is reset. 
         [0034]      FIG. 4C  is a flow diagram illustrating one embodiment a Purge cycle performed at hydration system  250 . In one embodiment, the Purge cycle is implemented to flush the ink lines to prevent clogging from dehydrated ink or ink that contains settling particulate. At processing block  462 , all pumps and solenoids within hydration system  250  are deactivated. At processing block  464 , the fill timer is reset. 
         [0035]    At processing block  466 , controller  252  activates Pump P 2 , solenoid S 2  and the manifold  254  solenoids. At processing block  468 , a wait state is initiated. In one embodiment, the wait state is maintained for ten seconds. At processing block  468 , controller  252  deactivates Pump P 2 , solenoid S 2  and the manifold  254  solenoids. At decision block  480 , a determination is made as to whether the fluid at cap  222  is at the predetermined threshold. If cap  222  is at the predetermined threshold, a warning message may be generated providing an indication to check the purge system. If not at the predetermined threshold, the Start cycle may be initiated. 
         [0036]    Throughout the foregoing description, for the purposes of explanation, numerous specific details were set forth in order to provide a thorough understanding of the invention. It will be apparent, however, to one skilled in the art that the invention may be practiced without some of these specific details. Accordingly, the scope and spirit of the invention should be judged in terms of the claims which follow.