Patent Publication Number: US-6334391-B1

Title: Ink cartridge valve system

Description:
BACKGROUND 
     1. Field of the Invention 
     This patent relates to liquid dispensing cartridges for automated dispensing systems. More specifically, this patent relates to a dispensing valve system attachable to an ink cartridge that automatically opens and closes in response to pressure from the ink. 
     2. Description of the Related Art 
     Lithography is a printmaking process dating back to the 1700s in which ink is applied to a plate having both image and non-image areas. The image areas are ink-receptive and water-repellent. The non-image areas are water-receptive and ink-repellent. In rotary type lithographic presses the ink plate is mounted on a cylinder that rotates during printing. In one typical configuration, the plate cylinder picks up the ink at the image areas and transfers the image to a blanket cylinder which then transfers the image to the paper. 
     In multi-color sheet-fed presses, up to ten inking stations can be placed in series. Each station has its own ink feeding system and handles a separate color. As the paper sheet moves from station to station, a new color is put down at each station. 
     Because lithographic ink is thixotropic, conventional lithographic ink feeding systems require a complex system of drums, vibrators and fountain rollers. In a typical lithographic ink feeding system, workers remove lithographic ink from a drum (or, in some cases, smaller tins) with specially made spatulas and spread the ink across a tray (the ink fountain). Fountain rollers roll against the ink fountain to pick up the ink and transfer it to the plate cylinder. The process is labor intensive and subject to error. 
     Storing lithographic ink in drums can result in wasted ink if the entire drum is not used because it is difficult to store and reuse ink in drums. The lithographic ink itself is prone to oxidation which can result in color variations from one press run to another, and even from sheet to sheet within a single run. In addition, upon exposure of the ink to the atmosphere, volatile organic compounds (VOCs) evaporate, which can cause ink spoilage. 
     Consequently, many modern printers, including sheet fed lithographic printers, use smaller cartridges to dispense ink. During printing the ink cartridge moves back and forth across the fountain, dispensing ink into the fountain or directly onto an ink form roller to provide an even, consistent layer of ink. In automated presses, the amount of ink in the fountain is continually monitored and replenished as needed. 
     Ink cartridges can be easily filled, transported, used and reused. The cartridge minimizes exposure of the ink to the atmosphere and also minimizes the amount of residual ink left in the cartridge after use. The cartridge typically comprises a hollow cylindrical body, a plunger at one end and a dispensing fitment at the opposite end. The cylindrical body is filled with ink. The plunger serves as a piston within the cylindrical body to extrude the contents of the dispenser when the plunger is forced toward the dispensing end by, for example, pneumatic pressure. 
     The dispensing fitment is mounted in sealing engagement within the dispensing end of the cylindrical body and has a valve and nozzle for controlling the flow of ink. In one ink cartridge described in U.S. application Ser. No. 09/470,747, now U.S. Pat. No. 6,192,797 owned by the assignee of the present application, the valve is recessed below the edge of the cartridge and the nozzle extension is detachable so that the valve and nozzle extension do not become damaged during shipment. When ready to use at the printing plant, the nozzle extension is attached to the recessed valve and extends beyond the end of the cylindrical body. The valve must be manually opened to allow ink to flow. 
     While this type of dispensing cartridge is suitable for its particular purpose, it requires that the valve be manually opened and closed. Thus there exists a need for an improved ink cartridge dispensing valve system that operates in response to pressure from the ink to open and close. 
     Therefore it is an object of the present invention to provide an ink cartridge dispensing valve system that opens and closes in response to pressure from the ink. 
     Another object of the present invention is to provide an ink cartridge dispensing valve system that can be attached to a recessed universal attachment post at the printing press. 
     A further object of the present invention is to provide an attachable dispensing valve that can be used in a sheet fed lithographic printing press with a hand gun or with an automated printing system. 
     Still another object of the present invention is to provide an ink cartridge dispensing valve system that minimizes exposure of the ink to the atmosphere. 
     Yet another object of the present invention is to provide an ink cartridge dispensing valve system having a recessed universal attachment post for easy packing, shipping and storing. 
     Further and additional objects will appear from the description, accompanying drawings, and appended claims. 
     SUMMARY OF THE INVENTION 
     The present invention is an improved ink cartridge of the type used to dispense ink in automatic lithographic presses. The ink cartridge comprises a hollow cylindrical body for holding a supply of extrudable ink and has a dispensing end and a plunger end. The plunger end is closed by a plunger adapted to serve as a piston within the cylindrical body to extrude the contents of the dispenser when the plunger is forced toward the dispensing end by pneumatic or mechanical pressure. The dispensing end is closed by a dispensing fitment affixed thereto by glue or other suitable means. The improvement comprises an attachment post mounted over a central aperture in the dispensing fitment, the attachment post having a sidewall and a top wall, the top wall having a plurality of openings therein; a nozzle mounted over the attachment post and defining a substantially cylindrical space; a plate mounted within the substantially cylindrical space, the plate having a central opening; and a spring mounted within the substantially cylindrical space on the side of the plate away from the attachment post top wall to bias the plate in sealing engagement with the attachment post top wall. When pressure is exerted on the plate by the ink, the spring compresses, allowing ink to be extruded through the nozzle. 
    
    
     THE DRAWINGS 
     FIG. 1 is an exploded perspective view of an ink cartridge dispensing system according to the present invention; 
     FIG. 2 is a cross-sectional view of the ink cartridge dispensing system of FIG. 1 shown in the closed position; 
     FIG. 3 is a cross-sectional view of the ink cartridge dispensing system of FIG. 1 shown in the open position; and 
     FIG. 4 is a top plan view of the attachment post of the ink cartridge dispensing system of FIG.  1 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Turning to the drawings, there is shown in FIG. 1 an exploded view of an ink cartridge dispensing system  10  made according to the present invention for use with a sheet fed lithographic press. The ink cartridge dispensing system  10  comprises a nozzle  12 , a spring  14 , an annular plate  16  and an attachment post  18 . The attachment post  18  may be formed as an integral part of the dispensing fitment  20 . 
     The dispensing fitment  20  is mounted in sealing engagement with the top end of the cartridge body  22 . The dispensing fitment  20  may be glued to the cartridge body  22  or attached by any other suitable means. The top end of the cartridge body  22  terminates in a rim or edge  24 . 
     Preferably, the cartridge body  22  is made of convolutely wound paper lined internally with polymeric material, although any suitable materials may be used, including, depending on the application, metal or plastic. In the preferred embodiment the dispensing fitment  20 , attachment post  18  and nozzle  12  are made of plastic. In practice, the cartridge body  22  typically is about nine or thirteen inches long, but any suitable length may be used depending on need. 
     In automated lithographic printing presses, the ink cartridge is mounted in an inverted position within a cartridge carriage (not shown). During operation, the carriage moves laterally along the length of a fountain roller while an ink level sensor constantly monitors the amount of ink in the fountain roller to determine the exact locations where ink is needed. When a low level of ink is detected by the sensor, the controller activates an air supply which forces air against a pneumatically controlled plunger slidingly engaged within the cartridge, which then forces ink onto the fountain roller. The ink cartridge dispensing system  10  of the present invention was specifically designed to work with automated ink dispensing systems of the type just described. 
     The dispensing fitment  20  is generally cup-shaped and comprises a substantially circular disk  26  and an annular sidewall  28  formed around the periphery of the disk  26  and extending upwardly therefrom (upward being defined as the direction away from the bottom or plunger end). An aperture is located at the center of the circular disk  26  through which ink may flow. A closure flange  30  extends radially outwardly from the top end of the annular sidewall  28 . When the dispensing fitment  20  is fully inserted into the cylindrical body  22 , the closure flange  30  abuts the rim  24  of the cylindrical body  22  to prevent further insertion of the dispensing fitment  20 . 
     The attachment post  18  is mounted on the circular disk  26  over the central aperture. As shown in FIGS. 2 and 3, the attachment post  18  has a substantially cylindrical sidewall  32  extending upwardly from the perimeter of the circular aperture and a convex top wall  34 . As best seen in when viewed from above (FIG.  4 ), the convex top wall  34  comprises a top plug  36  centrally disposed over the circular disk aperture and connected to the sidewall  32  by four arcuate bridges  38 . The top plug  36 , bridges  38  and sidewall  32  define four openings  40  through which the ink can flow when the dispensing system  10  is in the open position. 
     Referring to FIGS. 2 and 3, the nozzle  12  fits over the attachment post  18  in fixed relationship thereto. In the illustrated embodiment, the nozzle  12  is screwed upon the externally threaded sidewall  32 , although any suitable means of attachment will suffice. 
     The spring  14  and the annular plate  16  are disposed within the nozzle  12  in a cylindrical space  42  above the attachment post  18 . The plate  16  has a centrally disposed hole  44  through which ink may flow. The plate  16  is made of a material that is impervious to ink, such as polyethylene. In the preferred embodiment shown in FIG. 3, the hole  44  has a cylindrical portion  46  and a concave portion  48 . The upper wall  50  of the concave portion  48  mates with the convex top wall  34  of the attachment post  18  to form a seal when the dispensing system is in the CLOSED position (FIG.  2 ). 
     The spring  14  also has a hole in the middle and/or is pervious to ink. The spring  14  is compressible and resilient, and serves to bias the plate  16  against the attachment post  18  to seal off the flow of ink. 
     The CLOSED position of the dispensing system  10  is shown in FIG.  2 . The spring  14  is expanded so that the spring  14  and plate  16  fill the cylindrical space  42  within the nozzle  12 . The spring  14  biases the plate  16  against the attachment post  18 . In this position, the plate  16  is seated against the plug  36  to seal off the channel  44  through the plate  16 . Ink cannot flow through the nozzle. 
     The OPEN position of the dispensing system is shown in FIG.  3 . When pressure from the ink impinges on the dispensing system  10 , the spring  14  compresses and the plate  16  disengages the attachment post top wall  34 . Ink then flows through the openings  40  in the attachment post top wall  34  and through the nozzle  12 . 
     Thus the present invention provides a dispensing system for an ink cartridge having a spring loaded plate  18 . The cartridge automatically dispenses ink when the plunger end is depressed, forcing ink through the nozzle. The present invention is particularly suitable as an ink dispenser for use with a sheet fed lithographic press having an automatic ink level sensor. 
     Other modifications and alternative embodiments of the invention are contemplated which do not depart from the spirit and scope of the invention as defined by the foregoing teachings and appended claims. For example, it is contemplated that attachment post top wall may be flat or some other suitable shape. It is intended that the claims cover all such modifications that fall within their scope.