Abstract:
Damage is prevented in printing systems by allowing fluid from the printing system&#39;s fluid delivery system to expand. In one embodiment, this is accomplished by fluidly connecting a fluid expansion receptacle to the fluid delivery system. The fluid expansion receptacle provides volumetric compliance so that if printing fluid in the system expands, such as due to freezing, the fluid is able to expand into the fluid expansion receptacle and not damage the printing system.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     Inkjet printing technology is used in many commercial products such as computer printers, graphics plotters, copiers, and facsimile machines. One type of inkjet printing, known as “drop on demand,” employs one or more inkjet pens that eject drops of ink onto a print medium such as a sheet of paper. The pen or pens are typically mounted to a movable carriage that traverses back-and-forth across the print medium. As the pens are moved repeatedly across the print medium, they are activated under command of a controller to eject drops of ink at appropriate times. With proper selection and timing of the drops, the desired pattern is obtained on the print medium.  
         [0002]     An inkjet pen generally includes at least one drop-generating device known as a printhead, which has a plurality of nozzles or orifices through which the drops of ink are ejected. Adjacent to each nozzle is a firing chamber that contains the ink to be ejected through the nozzle. Ejection of an ink drop through a nozzle may be accomplished using any suitable ejection mechanism, such as thermal bubble or piezoelectric pressure wave to name a few. Ink is delivered to the firing chambers from an ink supply. The ink supply can be wholly contained within the pen body. Such an ink supply is considered to be “on-board” as the whole ink supply is carried on the carriage. With this arrangement, the entire pen, including the printhead, is replaced when the ink runs out.  
         [0003]     In “off-board” or “off-axis” printing systems, the ink supply can comprise a stationary ink container located separately from the pen. The ink container is fluidly coupled to a chamber in the pen body via a fluid delivery system, which typically includes flexible tubing. Printing fluids other than ink, such as preconditioners and fixers, can also be provided. Off-axis printing systems often include multiple ink or fluid containers and multiple pens and printheads. The stationary position and relatively easy access of an off-axis supply can allow for relatively large volumes of printing fluids to be stored and delivered. The use of replaceable fluid containers that are separate from the printhead allows the containers to be replaced without replacing the printhead. The printhead is then replaced at or near the end of printhead life, and not whenever a container is replaced. An off-axis supply also provides for a lighter pen and carriage assembly. This generally requires relatively less energy to move, while moving faster, quieter, and/or with less vibration.  
         [0004]     A concern with printing systems is that during shipping the system can be exposed to freezing temperatures, which could cause printing fluid in the system to freeze. Because most printing fluids contain water, they expand when freezing. This expansion can damage the fluid delivery system, such as causing the tubing to burst. One approach to avoiding such damage is to ship the printing systems without printing fluid. However, this approach creates certain logistical problems. For one, it is usually desirable to test a printing system at the factory prior to shipping to a customer. Such testing requires that the printing system be fully wetted. However, it is difficult and not cost efficient to wet a new printing system, test it, and then remove all of the printing fluid prior to transportation. Also, the occasion may arise where the user needs to return the printing system, such as for service or at the end of a lease. In this case, it is impractical to drain the printing fluid from the system prior to reshipment. 
     
    
     DESCRIPTION OF THE DRAWINGS  
       [0005]     The subject matter that is regarded as the invention is particularly pointed out and distinctly claimed in the concluding part of the specification. The invention, however, may be best understood by reference to the following description taken in conjunction with the accompanying drawing figures in which:  
         [0006]      FIG. 1  is a schematic block diagram depicting a conventional inkjet printing system.  
         [0007]      FIG. 2  is a schematic block diagram depicting one embodiment of an apparatus including a printing system and fluid expansion receptacles.  
         [0008]      FIG. 3  is a perspective view of one embodiment of a fluid expansion receptacle.  
         [0009]      FIG. 4  is another perspective view of the fluid expansion receptacle of  FIG. 3 .  
         [0010]      FIG. 5  is a cross-sectional side view of the fluid expansion receptacle, taken along line  5 - 5  of  FIG. 4 , showing the fluid expansion receptacle connected to a fluid delivery system.  
         [0011]      FIG. 6  is a top view of a housing from the fluid expansion receptacle of  FIG. 3 .  
         [0012]      FIG. 7  is a perspective view of another embodiment of a fluid expansion receptacle.  
         [0013]      FIG. 8  is another perspective view of the fluid expansion receptacle of  FIG. 7 .  
         [0014]      FIG. 9  is a cross-sectional side view of the fluid expansion receptacle, taken along line  9 - 9  of  FIG. 8 , showing the fluid expansion receptacle connected to a fluid delivery system.  
         [0015]      FIG. 10  is a side view of the fluid expansion receptacle of  FIG. 7 , shown locked in position. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0016]     Referring to the drawings wherein identical reference numerals denote the same elements throughout the various views,  FIG. 1  shows a conventional inkjet printing system  10 . As used herein, the term “printing system” is intended to encompass any system or device that prints on a print medium (i.e., produces hard copy). Such devices include, but are not limited to, computer printers, graphics plotters, copiers, facsimile machines and the like. Furthermore, the term “inkjet printing system” refers to any device that uses inkjet technology for producing hard copy.  
         [0017]     The inkjet printing system  10  includes a print carriage  12  that includes receiving stations or bays for supporting one or more inkjet pens  14 . In the illustrated embodiment, each inkjet pen  14  includes at least two printheads  16  that eject drops of printing fluid through a plurality of orifices or nozzles formed therein. As used herein, the term “printing fluid” refers to any fluid used in a printing process, including but not limited to inks, preconditioners, fixers, etc. The inkjet pens  14  are fluidly coupled to a fluid delivery system  17  that includes a fluid supply station  18  and one or more supply tubes  20 . The fluid supply station  18  includes one or more fluid containers  22  that hold various printing fluids which can be pressurized or at atmospheric pressure. The supply tubes  20  are typically made of a flexible material.  
         [0018]     By way of example only, the printing system  10  is shown to have six fluid containers  22  and three inkjet pens  14 . In this case, each pen  14  is connected to two of the fluid containers  22  via a pair of corresponding supply tubes  20 , and the pens  14  are configured so that each of the two printheads  16  is in fluid communication with a different one of the two fluid containers  22 . Alternatively, the printing system  10  could be configured to have an equal number of inkjet pens  14  and fluid containers  22 . In such case, each pen  14  would be connected to a corresponding one of the fluid containers  22  via a respective one of the supply tubes  20 .  
         [0019]     The printing system  10  also includes a media transport assembly  24  that is positioned relative to the carriage  12  so as to define a print zone adjacent to the printhead nozzles. The media transport assembly  24  positions a print medium  26 , such as paper, card stock, transparencies or the like, in the print zone so that drops of printing fluid ejected by the printheads  16  are directed toward the print medium  26 . In one embodiment, the carriage  12  is a scanning carriage that traverses the inkjet pens  14  back-and-forth across the print medium  26 . Typically, the printhead nozzles are arranged in one or more columns or arrays such that properly sequenced ejection of printing fluid causes characters, symbols, and/or other graphics or images to be printed on the print medium  26  as the print carriage  12  and the print medium  26  are moved relative to each other.  
         [0020]     The print carriage  12 , the inkjet pens  14 , the fluid containers  22  and the media transport assembly  24  are electrically interconnected to a print controller  28  that controls various system functions. The controller  28  receives data from a host system (not shown) and includes memory for temporarily storing the data. The data defines a print job for the inkjet printing system  10  and includes one or more print job commands and/or command parameters. In response to the data, the controller  28  provides control of the inkjet pens  14 , including timing control for ejection of ink drops from the printhead nozzles. The controller  28  also controls the carriage drive system and the media transport assembly  24  to provide the desired relative positioning of the printhead nozzles and the print medium  26 .  
         [0021]      FIG. 2  shows one embodiment of an apparatus  30  that includes a printing system, such as the inkjet printing system  10  depicted in  FIG. 1 , and one or more fluid expansion receptacles  32  that are fluidly connected to the fluid delivery system  17  in place of the inkjet pens  14 . The fluid expansion receptacles  32 , which are described in more detail below, provide volumetric compliance so as to allow fluid from the fluid delivery system  17  to expand. This allows printing fluid to expand without damaging the printing system  10  when the apparatus  30  is exposed to environments in which the printing fluid could freeze.  
         [0022]     Unlike the inkjet pens  14 , the fluid expansion receptacles  32  are not capable of ejecting drops of printing fluid. Thus, the apparatus  30  is incapable of printing. For this reason, the pens  14  generally are replaced with the fluid expansion receptacles  32  only in circumstances in which the printing system will not be used for printing and possibly could be subjected to freezing temperatures. Such circumstances include, but are not necessarily limited to, shipping and long term storage. Once these circumstances are over, the fluid expansion receptacles  32  are removed and pens  14  are installed so as to convert the apparatus  30  into a functioning printing system.  
         [0023]     Although not required, there can be one expansion receptacle  32  for each pen  14  to provide a one-for-one replacement. Thus, the apparatus  30  of  FIG. 2  is shown as having three expansion receptacles  32 . However, it should be noted that the present invention is not limited to printing systems having six fluid containers  22  and three inkjet pens  14 ; it can be used with printing systems having any number of fluid containers and pens, including an equal number of containers and pens. Furthermore, the present invention is not limited to inkjet printing systems and can be implemented with a wide variety of printing systems.  
         [0024]     Turning to  FIGS. 3-6 , one embodiment of a fluid expansion receptacle  32  is shown. This fluid expansion receptacle  32  includes a housing  34  that defines two internal chambers  36 . The housing  34 , which can be made of any suitable material, has four side walls  38 ,  40 ,  42 ,  44 , a bottom wall or base  46 , and an open top. Each one of the four side walls  38 ,  40 ,  42 ,  44  is joined at right angles along its lateral edges to adjacent side walls and along its lower edge to a corresponding edge of the base  46 . While the housing  34  is shown as having a rectangular cross-sectional shape, such configuration should not be interpreted as limiting. Any number of housing shapes may be utilized. The housing  34  includes a divider wall  48  extending between opposing side walls  38  and  42  so as to separate the interior of the housing  34  into the two chambers  36 . The divider wall  48  has a slot  50  formed therethrough from top to bottom and approximately midway between the opposing side walls  38  and  42 . The slot  50  receives a locking tab  52 , which is capable of sliding longitudinally in the slot  50 . The locking tab  52  is a slender, elongated member that extends beyond both ends of the housing  34 . An enlargement  54  is formed on the lower end of the locking tab  52 .  
         [0025]     The housing  34  includes two access holes  56  formed through the base  46  on either side of the divider wall  48  so that each access hole  56  is associated with a respective one of the chambers  36 . As best seen in  FIG. 5 , a hollow needle  58  is mounted in each access hole  56  so as to extend outwardly from the base  46 . A shroud  60  is formed on the base  46  so as to surround the needles  58 . The shroud  60  protects the needles  58  from inadvertent contact and also helps with alignment when installing the fluid expansion receptacle  32 . Two retention hooks  62  are also formed on the underside of the base  46  and extend outwardly therefrom. The retention hooks  62  are located adjacent to the shroud  60 , on opposite sides thereof. A slot  64  is formed in each side of the shroud  60  for receiving the tips of the retention hooks  62 .  
         [0026]     Preferably, although not necessarily, each of the two chambers  36  is filled with a fluid absorbing material  66 , such as foam. The fluid absorbing material  66  captures printing fluid that is received in the chambers  36  so as to prevent leakage of such printing fluid from the fluid expansion receptacle  32 . A film  68  attached to the top surface of the housing  34  retains the fluid absorbing material  66  in the chambers  36  and prevents captured printing fluid from wicking out of the fluid expansion receptacle  32 . The film  68  can be attached in any suitable manner, such as heat staking.  
         [0027]      FIG. 5  shows a fluid connection between the fluid expansion receptacle  32  and the fluid delivery system  17 , wherein a fluid communication path is established between each chamber  36  and the respective fluid containers  22 . In the illustrated embodiment, there are two fluidic interconnects associated with each fluid expansion receptacle  32 . Each fluidic interconnect includes a septum  70  that is made of a resilient material such as rubber and has a self-sealing slit formed therein. Each septum  70  is retained in a ring or cap  72  that is crimped over the septum  70 . The cap  72  is mounted to a septum bushing  74 , which is fluidly connected to a respective one of the supply tubes  20  (not shown in  FIG. 5 ). When a fluid expansion receptacle  32  is installed in one of the receiving stations of the carriage  12  in place of an inkjet pen, the shroud  60  fits over or encloses the two septa caps  72  associated with the receiving station, and the hollow needles  58  are inserted through the self-sealing slits formed in the respective septa  70 . The shroud  60  is provided with an inner conical portion  76  to facilitate receipt of the septa caps  72  and to align the septa  70  with the needles  58 .  
         [0028]     With the fluid expansion receptacle  32  so installed, a fluid communication path is established between each chamber  36  and its respective fluid containers  22  via the supply tube  20 , the bushing  74 , and the needle  58 . Printing fluid is thus able to freely expand from the fluid delivery system  17  into the chambers  36 . If the apparatus  30  is exposed to freezing temperatures such that the printing fluid freezes, the fluid expands into the chambers  36  and does not damage the fluid delivery system  17 . The chambers  36  should be sized to provide sufficient volumetric compliance for this purpose. The amount of volumetric compliance needed depends on the volume capacity of the fluid delivery system  17 .  
         [0029]     When the fluid expansion receptacle  32  is installed in the manner described above, the retention hooks  62  engage the lower lips formed by the septa caps  72  to hold the fluid expansion receptacle  32  in position. The locking tab  52  can be moved from a retracted position (shown in dotted lines in  FIG. 5 ) to a deployed position (shown in dotted lines in  FIG. 5 ) so that the enlargement  54  engages the lower lips of the septa caps  72  between the two caps  72  to further secure the fluid expansion receptacle  32  in position. This fastening prevents the fluid expansion receptacles  32  from being unintentionally dislodged by the forces exerted thereon by freezing printing fluid. When a user intentionally removes a fluid expansion receptacle  32  from the receiving station, the needles  58  are extracted from the septa  70  and the self-sealing slits re-seal due to the resiliency of the septa  70 .  
         [0030]     Referring to  FIGS. 7-10 , another embodiment of a fluid expansion receptacle  132  is shown. Like that the fluid expansion receptacle of the first embodiment, the fluid expansion receptacle  132  can be used to replace the inkjet pens of a printing system to form an apparatus  30  such as that shown in  FIG. 2 . The fluid expansion receptacle  132  includes a housing  134  that defines two internal chambers  136 . The housing  134 , which can be made of any suitable material, has four side walls  138 ,  140 ,  142 ,  144 , a bottom wall or base  146 , and an open top. Each one of the four side walls  138 ,  140 ,  142 ,  144  is joined at right angles along its lateral edges to adjacent side walls and along its lower edge to a corresponding edge of the base  146 . While the housing  134  is shown as having a rectangular cross-sectional shape, such configuration should not be interpreted as limiting. Any number of housing shapes may be utilized. The housing  134  includes a divider wall  148  extending between opposing side walls  138  and  142  so as to separate the interior of the housing  134  into the two chambers  136 .  
         [0031]     The housing  134  includes two access holes  156  formed through the base  146  on either side of the divider wall  148  so that each access hole  156  is associated with a respective one of the chambers  136 . As best seen in  FIG. 9 , a hollow needle  158  is mounted in each access hole  156  so as to extend outwardly from the base  146 . A shroud  160  is formed on the base  146  so as to surround the needles  158 . The shroud  160  protects the needles  158  from inadvertent contact and also helps with alignment when installing the fluid expansion receptacle  132 . The housing  134  further includes two locating flanges  178  extending outwardly from the base  146 . The locating flanges  178  are situated on the lower rear corners of the housing  134 , behind the shroud  160 . Each locating flange  178  has a substantially triangular shape so as to define a rearward-facing, sloped abutment surface  180 .  
         [0032]     Preferably, although not necessarily, each of the two chambers  136  is filled with a fluid absorbing material  166 , such as foam. The fluid absorbing material  166  captures printing fluid that is received in the chambers  136  so as to prevent leakage of such printing fluid from the fluid expansion receptacle  132 . A film  168  attached to the top surface of the housing  134  retains the fluid absorbing material  166  in the chambers  136  and prevents captured printing fluid from wicking out of the fluid expansion receptacle  132 . The film  168  can be attached in any suitable manner, such as heat staking.  
         [0033]      FIG. 9  shows a fluid connection between the fluid expansion receptacle  132  and the fluid delivery system  17 , wherein a fluid communication path is established between each chamber  136  and the respective fluid containers  22 . In the illustrated embodiment, there are two fluidic interconnects associated with each fluid expansion receptacle  132 . Each fluidic interconnect includes a septum  170  that is made of a resilient material such as rubber and has a self-sealing slit formed therein. Each septum  170  is retained in a ring or cap  172  that is crimped over the septum  170 . The cap  172  is mounted to a septum bushing  174 , which is fluidly connected to a respective one of the supply tubes  20  (not shown in  FIG. 9 ). When a fluid expansion receptacle  132  is installed in one of the receiving stations of the carriage  12  in place of an inkjet pen, the shroud  160  fits over or encloses the two septa caps  172  associated with the receiving station, and the hollow needles  158  are inserted through the self-sealing slits formed in the respective septa  170 . The shroud  160  is provided with an inner conical portion  176  to facilitate receipt of the septa caps  172  and to align the septa  170  with the needles  158 .  
         [0034]     This fluid expansion receptacle  132  is used in conjunction with printing systems in which the carriage  12  is provided with one or more pen latches. A pen latch is a conventional element used in many printing systems that is pivotally attached to the carriage and is ordinarily used to latch one or more inkjet pens in place in the carriage receiving stations.  FIG. 10  shows the fluid receptacle  132  secured in position with a pen latch  182 . In this case, the pen latch  182  is pivotally connected to the carriage (not shown in  FIG. 10 ) at pivot point  184 . By operating the handle  186 , the pen latch  182  can be locked into a latching position as shown in  FIG. 10 . The pen latch  182  can also be opened into a release position by pulling up on the handle  186 . To secure the fluid expansion receptacle  132 , a pocket shipping restraint  188  having sloped side edges  190  is first placed into the receiving station of the carriage. The pocket shipping restraint  188  is designed to fit into the receiving station and take up the load an inkjet pen would normally receive. The fluid expansion receptacle  132  is then placed into the receiving station so that the abutment surfaces  180  of the flanges  178  engage the appropriate side edge  190  of the pocket shipping restraint  188 . The fluid expansion receptacle  132  is thus aligned with the fluid delivery system  17  (not shown in  FIG. 10 ). The pen latch  182  is then locked into its latching position so that the fluid expansion receptacle  132  is locked into position between the pen latch  182  and the pocket shipping restraint  188 .  
         [0035]     With the fluid expansion receptacle  32  installed in the manner described above, a fluid communication path is established between each chamber  136  and its respective fluid container  22  via the supply tube  20 , the bushing  174 , and the needle  158 . Printing fluid is thus able to freely expand from the fluid delivery system  17  into the chambers  136 . If the apparatus  30  is exposed to freezing temperatures such that the printing fluid freezes, the fluid expands into the chambers  136  and does not damage the fluid delivery system  17 . The chambers  136  should be sized to provide sufficient volumetric compliance for this purpose. The amount of volumetric compliance needed depends on the volume capacity of the fluid delivery system  17 . The pen latch  182  prevents the fluid expansion receptacles  132  from being unintentionally dislodged by the forces exerted thereon by freezing printing fluid. When a user intentionally removes a fluid expansion receptacle  132  from the receiving station, the needles  158  are extracted from the septa  170  and the self-sealing slits re-seal due to the resiliency of the septa  170 .  
         [0036]     While the illustrated embodiments show two fluidic interconnects per fluid expansion receptacle and receiving station, it should be noted that the present invention is not so limited. For example, there could be only one fluidic interconnect per fluid expansion receptacle and receiving station. In this case, the fluid expansion receptacles would have a single chamber rather than two. Such an arrangement could be implemented with printing systems having one inkjet pen for every fluid container.  
         [0037]     While specific embodiments of the present invention have been described, it will be apparent to those skilled in the art that various modifications thereto can be made without departing from the spirit and scope of the invention as defined in the appended claims.