Abstract:
An ink jet cartridge assembly includes a pen body housing having an ink container, a jet plate coupled to the pen body for ejecting droplets of ink, and an ink inlet port through one wall of the housing. A connection tube is attached to the ink inlet. The connection tube has a septum which is remote from the inlet port, whereby the septum is adapted for connection to an ink supply.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates generally to ink jet printers, and more particularly to an inkjet print head cartridge assembly adapted for installation with reduced leakage.  
         BACKGROUND OF THE INVENTION  
         [0002]    Ink jet type printers typically employ a pen body that is moved in a transverse fashion across a print media. Contemporary disposable ink pen bodies typically include a self-contained ink container, a print head supporting a plurality of ink jet nozzles in combination with the ink reservoir, and a plurality of external electrical contacts for connecting the ink jet nozzles to driver circuitry.  
           [0003]    U.S. Pat. No. 5,686,947, which issued to Murray et al. on Nov. 11, 1997, discloses an inkjet printer which provides a continuous volume of ink to a pen body from a large, refillable ink reservoir permanently mounted within the ink jet printer. Flexible tubing, also permanently mounted within the ink jet printer, connects the reservoir to the pen body.  
           [0004]    Even with the possibility of replenishment of the ink container within a disposable ink jet pen body, there eventually comes a time when the pen body must be replaced. Therefore, there is a substantial need to supply the market with replacement pen bodies. Leakage of ink from pen bodies during installation has been a problem in the industry. Consequently, replacement pen bodies have been shipped with “breathing” caps so that the pressure inside the pen bodies is equal to atmospheric pressure during shipping to deal with the elevation and temperature changes. Installation of pen bodies with breathing caps can be messy, as ink can leak from the ink inlet or from the nozzles during the installation process.  
         SUMMARY OF THE INVENTION  
         [0005]    According to a feature of the present invention, ink pen bodies are provided for shipping with a connection tube that seals off the ink inlet to form a cartridge assembly. The pre-installed connection tube makes installation of cartridge assemblies according to the present invention into a printer a simple task.  
           [0006]    According to another feature of the present invention, an inkjet cartridge assembly includes a pen body housing having an ink container, a jet plate coupled to the pen body for ejecting droplets of ink, and an ink inlet port through one wall of the housing. A connection tube is attached to the ink inlet. The connection tube has a septum which is remote from the inlet port, whereby the septum is adapted for connection to an ink supply. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    These and other objects and features of the invention will become more fully apparent from the following description and appended claims taken in conjunction with the following drawings, where like reference numbers indicate identical or functionally similar elements.  
         [0008]    [0008]FIG. 1A is a front view of an ink jet pen body according to the present invention;  
         [0009]    [0009]FIG. 1B is a rear view of the inkjet pen body of FIG. 1A;  
         [0010]    [0010]FIG. 2 is a perspective view of the ink jet pen body and an attached connection tube to form a cartridge assembly according to the present invention;  
         [0011]    [0011]FIG. 3A is a perspective view of one embodiment of the connection tube shown of FIG. 2;  
         [0012]    [0012]FIG. 3B is a perspective view of another embodiment of the connection tube shown of FIG. 2;  
         [0013]    [0013]FIG. 3C is a perspective view of yet another embodiment of the connection tube shown of FIG. 2 and having a quick disconnect valve fitting;  
         [0014]    [0014]FIG. 4 is a cross-sectional view of the ink jet cartridge assembly taken along line  240 - 240  of FIG. 2;  
         [0015]    [0015]FIG. 5 is a view of an inkjet printer carriage and a disposable ink jet cartridge assembly according to FIGS.  1 - 4  shown connected to an ink line in a printer; and  
         [0016]    [0016]FIG. 6 is a perspective view of an ink jet printer carriage with disposable ink jet cartridge assemblies according to FIGS.  1 - 4  shown being supplied ink by remote large volume reservoirs. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0017]    A preferred pen body for use with the present invention is similar to those pen bodies well known in the art such as the 208-jet™ cartridge, Part No. 12A1970, from Lexmark International Inc., in Lexington, Ky. However, modifications to this basic assembly have been made to provide an opening for supplying ink from an external reservoir. Referring to FIGS. 1A and 1B, a pen body  100  according to the present invention includes a housing  102  as in the Lexmark Part. No. 12A1970, a jet plate  104 , an electrical connector assembly  106 , a memory chip assembly  108 , an ink container  110 , and atop lid  112 . The capacity of ink container  110  is preferably approximately 65 ml volume for commercially available ink jet printers, but other size pen bodies can be used with the present invention.  
         [0018]    Jet plate  104  includes a plurality of ink jet nozzles that may be conventional in design. The jet plate is mounted to a bottom surface of pen body housing  102  such that ink ejected from the jet plate deposits onto paper or other print media which is positioned on a platen below pen body  100 .  
         [0019]    Electrical connector assembly  106  is positioned on pen body housing  102  to align with a mating electrical connector assembly (not shown) on a pen body holder as is conventional for ink jet printers. Connector assembly  106  transfers electrical control signals from the main control electronics in the printer housing to jet plate  104  for controlling the printing operation in a manner well known in the art.  
         [0020]    Memory chip assembly  108  is attached to the pen body housing  102  using a conventional method, such as adhesive and is positioned to align with the mating electrical connector assembly (not shown) on a pen body holder as is conventional for inkjet printers. Memory chip assembly  108  has a memory chip to hold data for the pen body and the ink jet printer system, such as ink type and color and the amount of ink used for the pen body. The function of the memory chip assembly  108  is disclosed in U.S. Pat. No. 5,610,635, which issued to Murray et al. on May 11, 1997.  
         [0021]    Top lid  112 , preferably plastic, is attached, such as by ultrasonic welding, to housing  102 . The top lid has an integral opening and a female portion  114  of a quick disconnect fitting, preferably designed to standard female Luer Lock dimensions.  
         [0022]    [0022]FIG. 2 is a perspective view of the ink jet pen body  100  of FIGS. 1A and 1B and a connection tube  200  attached to pen body  100  to form a cartridge assembly. Connection tube  200  consists of a quick disconnect fitting  210 , a flexible tubing  220  and a septum assembly  230 . The connections from flexible tubing  220  both to quick disconnect fitting  210  and to septum assembly  230  are established by barb fittings. The flexible tubing is preferably made of polyurethane, but can be made of other proper materials. Quick disconnect fitting  210  mates with female portion  114  on top lid  112  of cartridge assembly  100 . Preferably, male portion  210  of the quick disconnect fitting is a conventional Luer Lock fitting. Female portion  114 , which is integral on the pen body and male portion of quick disconnect fitting  210  form a hermetic seal there between when they are connected.  
         [0023]    Many embodiments of connection tube  200  will occur to a person ordinarily skilled in the art. FIGS.  3 A- 3 C provide three examples thereof. In FIG. 3A, quick disconnect fitting  212  is a commercially available part, such as Part No. MTLL210-6 from Value Plastics, Inc. in Fort Collins, Colo. The quick disconnect fitting  214  in FIGS. 3B and 3C has a tube  216  connected to the bottom tip of male portion. Tube  216  is bonded to male portion of quick disconnect fitting  214  by conventional bonding methods known to those of skill in the art such as, for example, by an adhesive bond. The tube  216  may be formed of stainless steel, polyurethane, or other suitable material.  
         [0024]    In FIG. 3A, the septum assembly has two parts, a septum part  232  and an extension part  234  to connect the septum to tubing  220 . The septum is preferably a commercially available part, such as Part No.  84039  from Qosina Company in Edgewood, N.Y. Extension part  234  in FIG. 3A may be replaced by the commercially available parts, such as those shown in FIG. 3B as a barb Luer fitting  236  and an extension tube  238 . FIG. 3C shows an alternative of the septum. A quick disconnect valve fitting  240  is used to achieve the equivalent function of septum  232  to connect pen body  100  to the printer ink line.  
         [0025]    [0025]FIG. 4 is a cross-sectional view of pen body  100  and connection tube  200  attached, taking along line  240 - 240  of FIG. 2. Ink container  110  of pen body  100  is filled with a proper amount of ink  404 . An adequate volume of air  406  remains in ink container  110  after the factory ink filling process. The volume of air serves as a pressure buffer to absorb pressure surges during printing. Adequate air volume for the purpose of pressure buffering can vary greatly as a percentage of the volume of ink container  110 , and is determined by the requirement to the volume of ink  404 . The volume of ink  404  needs to be enough to cover a filter  408 . During printing, pen body  100  moves back and forth, causing ink  404  to slosh in ink container  110 . Therefore, increasing the volume of ink  404  helps to cover filter  408  during printing. When ink container  110  has a volume of approximately 65 ml, it is preferred that the volume of ink  404  be more than 25 ml. Pen body  100  is hermetically sealed by male-to-female quick disconnect fittings  114  and  210  on top and by nozzle plate tape  402  at the bottom. Nozzle plate tape  402  is a commercially available tape relying either on a thin layer of tape adhesive or on electrical static to stick to the nozzle plate. If a layer of adhesive is provided, the adhesive layer on the tape needs to be very thin so as to not form a blockage after tape  402  is removed when pen body  100  is installed into a printer.  
         [0026]    [0026]FIG. 5 is a perspective view of an ink jet print head cartridge assembly including pen body  100  with connection tube  200  installed into a carriage block  700  of a ink jet printer (not shown). An ink line valve  702  is open to expose a septum receiver  704  to connect connection tube  200 . A needle inside septum receiver  704  pierces through septum  232  of the connection tube  200 . Pull fluid communication between ink container  110  of pen body  100  and an ink line (not shown) is established when ink line valve  702  is closed. The internal pressure P in ink container  110  acts to draw ink from the ink line on the printer until internal pressure P equalizes with pressure in the ink reservoir on the printer. After the pressure equalization process, a customer can peal off nozzle tape  402  of nozzle plate  104  and start printing.  
         [0027]    The quick disconnect between septum receiver  704  and septum  232  is preferred to be totally clean hands and easy to operate. The quick disconnect function advantageously enables the easy removal of the ink jet cartridge assembly from carriage block  700 . Thus, when the print quality of jet plate  104  begins to degrade, an inkjet cartridge assembly can be easily removed and replaced with a new cartridge assembly having a new jet plate. The quick connect-disconnect can be achieved as known to one in the art with male-to-female connection when a male quick disconnect valve shown in FIG. 3C is used.  
         [0028]    The volume of ink drawn from the printer ink line to cartridge ink container  110  depends on elevation of the customer. With initial internal pressure P 0  of 20.7 inch Hg, the relationship between the ink volume drawn to ink container  110  and customer&#39;s elevation can be established following the ideal gas law, as known to one skilled in the art, and is shown in the following table, assuming that the ink line in the printer is full of ink just prior to the installation process.  
                                                                 Elevation (ft)   Ink Volume (ml)           at Customer   Drawn to Container                                        0   12.5           1,000   11.5           2,000   10.4           3,000   9.3           4,000   8.1           5,000   6.9           6,000   5.7           7,000   4.4           8,000   3.0           9,000   1.5           10,000   0                      
 
         [0029]    The above table assumes that the ink line is full of ink just before the cartridge assembly installation process. If the ink line is not full, the amount of ink drawn to ink container  110  is less than the volume shown in the table. The volume of ink drawn into container  110  adds to the initial ink volume  404  in container  110 . This ensures that cartridge filter  408  is fully covered during printing operation.  
         [0030]    [0030]FIG. 6 is a perspective of ink jet printer carriage block  700  loaded with a plurality of print head cartridge assemblies according to the present invention. Additional details of printer carriage block  700 , and of an inkjet printer in which it may be used, can be found in afore-mentioned U.S. Pat. No. 5,686,947.