Abstract:
A container including a first tank for receiving a liquid, a second tank that is selectively pressurizable, a check valve for permitting fluid flow from the first tank to the second tank, and a manifold structure having a first port fluidically coupled to the first tank and a second port fluidically coupled to the second tank.

Description:
BACKGROUND 
     The subject disclosure is generally directed to drop emitting apparatus. 
     Drop on demand ink jet technology for producing printed media has been employed in commercial products such as printers, plotters, and facsimile machines. Generally, an ink jet image is formed by selective placement on a receiver surface of ink drops emitted by a plurality of drop generators implemented in a printhead or a printhead assembly. For example, the printhead assembly and the receiver surface are caused to move relative to each other, and drop generators are controlled to emit drops at appropriate times, for example by an appropriate controller. The receiver surface can be a transfer surface or a print medium such as paper. In the case of a transfer surface, the image printed thereon is subsequently transferred to an output print medium such as paper. Some ink jet printheads employ melted solid ink. 
     It can be difficult to reduce bubbles in the ink provided to the drop generators. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic block diagram of an embodiment of an ink jet printing apparatus. 
         FIG. 2  is a schematic block diagram of an embodiment of a drop generator that can be employed in the printhead of the ink jet printing apparatus shown in  FIG. 1 . 
         FIG. 3  is a schematic block diagram of an embodiment of a recirculating ink delivery system that can be employed in the printing apparatus of  FIG. 1 . 
         FIG. 4  is a schematic block diagram of an embodiment of a manifold structure that can be employed in the recirculating ink delivery system of  FIG. 3 . 
         FIG. 5  is a schematic block diagram of an embodiment of another manifold structure that can be employed in the recirculating ink delivery system of  FIG. 3 . 
         FIG. 6  is a schematic isometric view generally illustrating a plurality of ink drop generators that are fluidically coupled to a finger manifold of the manifold structure of  FIG. 4  or  FIG. 5 . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is a schematic block diagram of an embodiment of a printing system that includes a supply of solid ink  11  which provides solid ink to a solid ink melter  13 . The solid ink melter  13  provides melted solid ink  33  to an ink reservoir  17  which supplies melted solid ink  33  to a printhead assembly  20  that can include a plurality of drop emitting drop generators  30  ( FIG. 2 ) for emitting drops of ink, for example. By way of illustrative example, the ink reservoir  17  can be attached to the printhead assembly  20  or integral therewith. 
     A controller  10  selectively energizes the drop generators of the printhead assembly  20  by providing a respective drive signal to each drop generator of the printhead assembly  20 . Each of the drop generators can employ a piezoelectric transducer. As other examples, each of the drop generators can employ a shear-mode transducer, an annular constrictive transducer, an electrostrictive transducer, an electromagnetic transducer, or a magnetorestrictive transducer. The printhead assembly  20  can be formed of a stack of laminated sheets or plates, such as of stainless steel, having suitable openings formed therein, for example. 
       FIG. 2  is a schematic block diagram of an embodiment of a drop generator  30  that can be employed in the printhead assemblies  20  of the printing apparatus shown in  FIG. 1 . The drop generator  30  includes an inlet channel  31  that receives melted solid ink  33  from a manifold, reservoir or other ink containing structure. The melted ink  33  flows into a pressure or pump chamber  35  that is bounded on one side, for example, by a flexible diaphragm  37 . An electromechanical transducer  39  is attached to the flexible diaphragm  37  and can overlie the pressure chamber  35 , for example. The electromechanical transducer  39  can be a piezoelectric transducer that includes a piezo element  41  disposed for example between electrodes  43  that receive drop firing and non-firing signals from the controller  10 . Actuation of the electromechanical transducer  39  causes ink to flow from the pressure chamber  35  to a drop forming outlet channel  45 , from which an ink drop  49  is emitted toward a receiver medium  48  that can be a transfer surface or a print output medium, for example. The outlet channel  45  can include a nozzle or orifice  47 . 
       FIG. 3  is a schematic block diagram of an embodiment of a recirculating ink delivery system that can be employed in the printing apparatus of  FIG. 1 . The recirculating ink delivery system includes a first tank  17 A that receives ink  33  through a valve  71 , for example. The first tank  17 A can be selectively pressurized, for example by controllably introducing pressurized air from a source of pressurized air  73  through a valve  75 . 
     The recirculating ink delivery system further includes a second ink tank  17 B that receives ink from the first tank  17 A via a check valve  77  that permits flow only from the first tank  17 A to the second tank  17 B. The second tank  17 B is selectively pressurizable, for example by controllably introducing pressurized air from the source of pressurized air  73  via a valve  79 . 
     The second tank  17 B is fluidically coupled to an input port  60 A of a manifold structure  60 , while the first ink tank  17 A is fluidically coupled to an output port  60 B of the manifold structure  60 . 
     The manifold structure  60  further includes a plurality of outlets  60 C that provide ink to drop generators, for example via intermediate finger manifolds  161  ( FIGS. 4 and 5 ). 
     The manifold structure  60  can be implemented in the printhead assembly  20  along with the drop generators  30  and the fluidic connections between the manifold structure  60  and the drop generators  30 . As described earlier, the printhead assembly  20  can comprise for example a stack of laminated sheets or plates. The first tank  17 A and the second tank  17 B can be attached to the printhead assembly, for example. 
     In normal printing operation, the first tank  17 A and the second tank  17 B are both vented to atmosphere, and ink  33  is appropriately introduced into the first tank  17 A. Since both tanks are vented to atmosphere, ink will flow into the second tank  17 B until the ink levels in both tanks  17 A,  17 B are substantially equalized. Ink can flow from either tank into the manifold structure  60 , which in turn feeds the drop generators. 
     The ink in the second tank  17 B can be recirculated, for example to reduce bubbles in the ink. With the ink in the tanks at a level that is less than full, for example at about half full, the second tank  17 B is pressurized while the first tank is vented to atmosphere. This closes the check valve  77  which prevents ink from flowing to the second ink tank  17 B, and causes ink to flow from the second tank  17 B to the manifold structure. This in turn causes ink to flow from the manifold structure  60  to the first tank  17 A where ink accumulates. When the first tank  17 A is full or when the second tank  17 B is nearly empty, for example, the second tank  17 B is vented to atmosphere, which allows the ink levels to be generally equalized in the first and second tanks  17 A,  17 B. After the ink levels are generally equalized, the foregoing transfer can be repeated, as appropriate. In this manner, the second tank  17 B comprises a source tank and the first tank comprises a sink tank, wherein ink is transferred from the source tank to the manifold structure  60 , and ink is transferred from the manifold structure  60  to the sink tank. 
     Purging can be accomplished for example by pressurizing the first tank  17 A and the second tank  17 B, which forces ink to flow from the manifold to the drop generators. 
       FIG. 4  is a schematic illustration of an embodiment of a manifold structure  60  that can be employed in the recirculating ink delivery system of  FIG. 3 . The manifold structure  60  includes an elongated primary manifold  61  and a plurality of finger manifolds  161  fluidically connected thereto. An input port  60 A and an output port  60 B can be located at longitudinally separated end portions of the primary manifold  61 . Recirculation flow is from the input port into the primary manifold, and from the primary manifold to the output port. 
     A plurality of ink drop generators  30  can be fluidically connected to each finger manifold, as schematically depicted in  FIG. 6 . 
       FIG. 5  is a schematic illustration of an embodiment of another manifold structure  60  that can be employed in the recirculating ink delivery system of  FIG. 3 . The manifold structure  60  includes a first elongated primary manifold  61  and a second elongated primary manifold  62  transversely separated from the first elongated primary manifold  61 . A plurality of finger manifolds  161  are fluidically connected between the first primary manifold  61  and the second primary manifold  62 . An input port  60 A can be located at one end portion of the first primary manifold  61 , while an output port  60 B can be located at one end portion of the second primary manifold  62 , for example at an end portion that is farthest from the input port  60 A. Recirculation flow is from the input port into the first primary manifold  61 , from the first primary manifold  61  into the finger manifolds  161 , from the finger manifolds  161  into the second primary manifold  62 , and from the second primary manifold  62  to the output port  60 B. 
     A plurality of ink drop generators  30  can be fluidically connected to each finger manifold, as schematically depicted in  FIG. 6 . 
     The claims, as originally presented and as they may be amended, encompass variations, alternatives, modifications, improvements, equivalents, and substantial equivalents of the embodiments and teachings disclosed herein, including those that are presently unforeseen or unappreciated, and that, for example, may arise from applicants/patentees and others.