Abstract:
A refillable fluid reservoir for a fluid ejection head, including a fluid reservoir having top, bottom and side walls defining an interior volume for having fluid; a venting port provided on one of the reservoir walls; and a fluid inlet port provided on one of the reservoir walls, the venting port and the fluid inlet port being located at substantially the same vertical level to increase volumetric efficiency and reduce staining.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of Invention  
         [0002]     This invention relates to controlling fluid quantity in a fluid ejection head.  
         [0003]     2. Description of Related Art  
         [0004]     Fluid ejector systems, such as drop-on-demand liquid ink printers, have at least one fluid ejector from which droplets of fluid are ejected towards a receiving sheet. For example, scanning inkjet printers are equipped with printheads containing fluid ink. The ink is applied to a sheet in an arrangement based on print data received from a computer, scanner or similar device. To control the delivery of the fluid to the sheet, fluid ejection heads are moved across the sheet to provide the fluid to the sheet, which is ejected as drops. Each drop corresponds to a liquid volume designated as a pixel. Each pixel is related to a quantity needed to darken or cover a particular unit area.  
         [0005]     In order to lower cost and improve performance by limiting inertia, moving-head fluid ejection systems are designed with low-weight fluid ejection heads. In order to minimize weight, the fluid ejection heads contain a relatively small quantity of fluid. Consequently, the fluid ejection heads (or their fluid reservoirs) must either be periodically replaced or refilled. Refillable cartridges are commonly used in home-use printers. Some heavier-use printers in industry attach the fluid ejector via an umbilical tube to a larger tank for continuous refilling. Other heavier-use printers periodically refill the fluid ejection head.  
       SUMMARY OF THE INVENTION  
       [0006]     Refilling cartridges requires frequent interaction by the user, and is considered disadvantageous for fluid ejectors used in volume production or connected by a network to the ejection data source. Umbilical systems can be expensive, requiring pressurization, tubing, tube harness dressing, and can suffer performance degradation from moisture loss, pressure fluctuations due to acceleration or temperature variation, and motion hysterisis from tubing harness drag.  
         [0007]     In the related art, two vertically aligned refill ports are provided on the side of a fluid ejection head. The refill ports are provided at a refill junction in a configuration where a top port is a venting port and a bottom port is a fluid inlet port. The fluid is introduced through a needle or tubing from a refill station which engages the fluid inlet port. Fluid is either pushed into the bottom port under pressure or a vacuum is applied to the top port to draw the fluid in through the bottom port. The fluid is introduced through a needle or tubing which engages the port. Fluid fill volume in a fluid reservoir, however, is limited in such related art designs because when the fluid level reaches either inlet port, the fluid tends to leak when the refill station is disengaged from the port. Thus, whether fluid exceeds the level of the lower port, leakage or staining will occur.  
         [0008]     Consequently, the fluid reservoir  110  in a fluid ejector  100  must be significantly underfilled in order to avoid excess fluid spilling out of the refilled fluid reservoir. This under-filling wastes available reservoir space and reduces the productivity of the fluid ejection device due to the greater frequency of refill operations.  
         [0009]     Accordingly, containers for consumable fluids in various applications of fluid ejection may require a configuration that wastes space and reduces productivity. Such applications include, but are not limited to, ink-jet printers, fuel cells, dispensing medication, pharmaceuticals, photo results and the like onto a receiving medium, injecting reducing agents into engine exhaust to control emissions, draining condensation during refrigeration, etc.  
         [0010]     This invention provides systems, methods and structures to utilize the maximum refill capacity of a fluid reservoir.  
         [0011]     This invention separately provides systems, methods and structure to prevent the spilling of fluid during a fluid refill operation.  
         [0012]     In various exemplary embodiments of the systems, methods and structures of the invention, a refill system for a fluid reservoir includes a venting port and a fluid inlet port. In various exemplary embodiments the venting port and the fluid inlet port are located at the same vertical level. This configuration allows the fluid reservoir to be volumetrically efficient while preventing the leakage of fluid from the fluid inlet port.  
         [0013]     In various exemplary embodiments, a refill system for a fluid reservoir includes a venting port and a fluid inlet port. In various exemplary embodiments, the venting port is located below the inlet port. A tube is run from the vent port and opens at a level at or above the level of the fluid inlet port. This allows the design to maximize the height of the fluid inlet port, while minimizing ink stain.  
         [0014]     In various exemplary embodiments, the venting port and the fluid inlet port are located at a top portion of the fluid ejection head. In various exemplary embodiments, the venting port and the fluid inlet port located at a top portion of the fluid ejection head have vertical inlet axes. In other various exemplary embodiments, the venting port and the fluid inlet port may have inlet axes which are at an angle relative to a vertical axis.  
         [0015]     In various exemplary embodiments according to the systems, methods and structure of the invention, the fluid inlet port and vent port are sealed by a ball valve seal to prevent fluid from spilling. It should be appreciated that other seals could be used. For example, needle septum, poppet valve, flapper valve, O-ring, piston seal, etc.  
         [0016]     These and other features and advantages of this invention are described in, or are apparent from, the following detailed description of various exemplary embodiments of the systems and methods according to this invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]     Various exemplary embodiments of the devices, systems and methods of this invention will be described in detail with reference to the following figures, wherein:  
         [0018]      FIG. 1  is an isometric view of an exemplary embodiment of a fluid refill system;  
         [0019]      FIG. 2  is an isometric view of a fluid ejection head according to an exemplary embodiment of the invention;  
         [0020]      FIG. 3  is a cross-sectional view of a fluid refill junction according to an exemplary embodiment of the invention;  
         [0021]      FIG. 4  is an isometric view of a second exemplary embodiment of a fluid refill system;  
         [0022]      FIG. 5  is an isometric view of a fluid ejection head according to a second exemplary embodiment of the invention;  
         [0023]      FIG. 6  is a cross-sectional view of a fluid refill junction according to a second embodiment of the invention;  
         [0024]      FIG. 7  is a isometric view of a fluid ejection head according to an exemplary embodiment of the invention; and  
         [0025]      FIG. 8  is an isometric view of a fluid ejection head according to an exemplary embodiment of the invention. 
     
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS  
       [0026]     The following detailed description of various exemplary embodiments of the fluid ejection systems according to this invention may refer to one specific type of fluid ejection system, e.g., an inkjet printer, for sake of clarity and familiarity. However, it should be appreciated that the principles of this invention, as outlined and/or discussed below, can be equally applied to any known or later-developed fluid ejection system, beyond the fluid jet printer specifically discussed herein.  
         [0027]     A fluid ejector, such as, for example, an inkjet printhead, is produced, distributed and/or installed with a fluid reservoir, such as, for example, and ink reservoir, typically filled with a fluid, such as, for example, ink. The fluid ejector, includes, in accordance with this invention, a portion referred to as a refill junction.  
         [0028]      FIGS. 1-3  show a fluid ejection system according to this invention having a fluid ejection head  100  connectable with a fluid refill station  150 . As shown in  FIG. 1 , the fluid ejection head  100  includes a refillable fluid container or reservoir  110  with a refill function  102 . The fluid reservoir  110  of the fluid ejection head  100  can be connected to the refill station  150  when a detector  160  detects, for example, that the fluid level in the fluid reservoir  110  has fallen below a predetermined level. Subsequently, the fluid reservoir  110  of the fluid ejection head  100  can be disconnected from the refill station  150  when the detector detects that the level in the fluid reservoir  110  has risen to, for example, a position above the predetermined level.  
         [0029]     As better shown in  FIG. 2 , fluid ejection head  100  has the refill junction  102  provided on a lateral side of the reservoir  110 . Refill junction  102  includes refill ports  114   a  and  114   b  and alignment holes  130 . In various exemplary embodiments, alignment holes  130  are used to align a retaining clip  111  when securing it to printhead  100  and/or to mate with corresponding alignment features  154  in the refill station  150 .  
         [0030]     In various exemplary embodiments, the retaining clip  111  serves to cover the refill junction  102  between the reservoir  110  and the refill station  150 .  FIG. 2  shows the front face  113  of the retaining clip. An air inlet port and an ink inlet port are collectively shown as refill ports  114 . Each refill port  114  has a respective injection tube or needle  152  on refill station  150  and is aligned thereto.  
         [0031]     When the reservoir  110  is low on fluid, the printhead  100  is transported to the refill station  150 . The refill ports  114  are then positioned to be aligned with the refill station needles or tubing  152  of refill station  150  and are engaged thereto. To aid in alignment, alignment holes  130  may also align with alignment features  154 .  
         [0032]     In various exemplary embodiments, refill port  114   a  is a fluid inlet port and  114   b  is a venting port. It should be appreciated that either refill port  114   a  or  114   b  may be the fluid inlet port on the venting port so long as the needles or tubes  152  located at refill station  150  correctly correspond.  
         [0033]     Each refill port  114  is provided with a valve which is normally closed to provide a seal. When the refill station needles or tubes engage the refill ports, the valves are opened. In various exemplary embodiments, one of the needles or tubes applies a pressure less than atmospheric, decreasing the pressure within the reservoir  110  and draining fluid from the second needle or tube that is connected to the fluid supply. In other exemplary embodiments, one of the needles or tubes is connected to a pressurized source of fluid which fills the reservoir  110  through one refill port while the second refill port is vented to atmospheric pressure.  
         [0034]     During this process, fluid may pool on the outside surfaces of the printhead resulting in staining, poor print quality and user contamination.  
         [0035]     In the exemplary embodiment shown in  FIGS. 2-3 , venting port  114   b  is located at substantially the same height as fluid inlet port  114   a . Moreover, both the refill ports  114   a  and  114   b  are located at an upper portion of the fluid ejection head refill junction  102 . This allows maximum use of the space of  110  reservoir, since it allows fluid to fill the reservoir  110  up to the height of fluid inlet port  114   a  before encountering staining.  
         [0036]     As shown in  FIG. 3 , the inlet ports  114 A,  114 B may be provided with a ball valve seal connection  120 . Ball valve seal  120  in exemplary embodiments includes a ball  122  biased by a spring  124  to be in contact with a seal  126 . In one exemplary embodiment, the seal is a compliant seal. In other exemplary embodiments seal  126  may be a septum type seal.  
         [0037]     When the reservoir  110  is to be refilled, the needle or tube engages the ball  122  to overcome the bias of the spring  124  and separates the ball  122  from the seal  126  to create a passage for fluid or air from the refill station to or from the reservoir  110 . When the needle or tube is removed from refill port  114 , the ball  122  is again biased by the spring  124  to come into contact with seal  126  to reduce or prevent fluid or air from escaping into or out of the reservoir  110 .  
         [0038]      FIGS. 4-6  show a second exemplary embodiment of the invention in which the refill ports  114   a ,  114   b  are vertically aligned.  
         [0039]     As in  FIG. 2 , refill ports  114   a  and  114   b  in  FIG. 5  are respectively a fluid inlet port and a venting port. According to an exemplary embodiment of the invention, fluid inlet port  114   a  is located on an upper portion of refill junction  102 . Venting port  114   b  is located below fluid inlet port  114   a . As better shown in  FIG. 6 , venting port  114 B is provided with a tube  128  which opens to the atmosphere at a level at or above the level of the fluid inlet port  114   a . By providing tube  128  with an opening  129  to the atmosphere at or above the level of fluid inlet port  114   a , the reservoir  110  is able to be filled up to the level of fluid inlet port  114   a , which in the exemplary embodiment is located at an upper portion of the refill junction  102 , which in turn is located at an upper portion of the fluid ejection head  100 . As such, even with a vertically aligned configuration, similar fluid capacity can be achieved as the prior embodiment without staining.  
         [0040]     In addition, according to one exemplary embodiment of the systems, methods and structures of the invention, tube  128  may have a ball valve seal whose operation is synchronized with the operation of the valves provided in refill ports  114 .  
         [0041]      FIG. 6  shows a section view of a fluid refill junction and fluid refill ports  114  of  FIG. 5 . According to an exemplary embodiment of the invention, ball valve seal  120  is provided at the junction of refill station  150  and reservoir  110  as in the prior embodiment. The ball valve seal  120  includes a ball  122  biased by spring  124  to be in contact with seal  126 . In one exemplary embodiment, seal  126  is a compliant seal. In other exemplary embodiments, seal  126  can be a septum type seal which is pierced by a needle or has a hole in it to receive a needle or tube from refill station  130  or a combination of a septum type seal with a hole.  
         [0042]     As shown in  FIG. 7 , according to an exemplary embodiment of the systems, methods and structure of the invention the refill ports  114   a, b  may be located at a top portion of the fluid ejection head  100 . The inlet axes of the refill ports  114  may be aligned vertically. In various exemplary embodiments, the inlet axes may be aligned at any suitable angle relative to a vertical axis, as shown in  FIG. 8 . It should be appreciated that refill station  150  needles and tubing must be provided and aligned to match the angle of the inlet axes. These embodiments allow additional fluid capacity for volumetric efficiency, at the possible expense of increased fluid ejector head height.  
         [0043]     While this invention has been described in conjunction with exemplary embodiments outline above, many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, the exemplary embodiments of the invention, as set forth above, are intended to be illustrative, not limiting. Various changes can be made without departing from the spirit and scope of the invention.