Abstract:
A bulk ink delivery system for ink jet printers and the like includes one or more cartridge housings which conform to the shape of a manufacturer&#39;s standard, ink-filled cartridge so that the cartridge housing may be substituted for the ink-filled cartridge normally associated with the printer. Inside the housing is situated an ink pump, a reservoir, and a control circuit for operating the ink pump. The ink pump replenishes the ink reservoir in the cartridge housing, and receives ink from one of several external ink bottles, one bottle for each color and one bottle for each cartridge housing. The control circuit for operating the pump includes a high volume primary level sensing switch, which monitors the quantity of ink in the internal reservoir within the cartridge housing. The control circuit energizes or de-energizes the pump to add more ink as required to the reservoir in order to maintain a pre-determined level of ink within the reservoir. An external status indicator unit which includes a plurality of indicator lights is viewable to the operator of the printer. The lights indicate the status of the ink delivery system.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]     This application is based on U.S. Provisional Application Ser. No. 60/585,165, which was filed on Jul. 2, 2004, and which is entitled “Bulk Ink Delivery System For Ink Jet Printers and The Like”, the disclosure of which is incorporated herein by reference. Applicants hereby claim priority to the aforementioned application under 35 U.S.C. 120. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     This invention relates to ink jet printers and the like, and more particularly relates to the ink cartridges and the supply of ink for such printers.  
         [0004]     2. Description of the Prior Art  
         [0005]     Ink jet printers, such as those which use the Seiko-Epson Writing Engine, rely primarily on one or more replaceable ink cartridges, one cartridge for each color. The cartridges contain a limited quantity of ink and must be replaced frequently. Cartridge replacement results in printer down time and disrupts the printing operation. This disruption occurs each time just one color cartridge must be changed.  
         [0006]     External bulk ink delivery systems are well known in the art for supplying a larger quantity of ink to the printers. However, such delivery systems are most commonly passive systems, using gravity feed, capillary feed, siphons or other mechanisms, instead of active electrical/mechanical devices, to transfer ink to the printing head.  
         [0007]     Also, such conventional ink delivery systems have inherent limitations, as their use often results in ink starvation or flooding at the printing head. These phenomena occur because the level of the ink immediately adjacent to the printing head is insufficiently maintained either due to limitations of the feed system or the need to manually adjust and replenish the ink reserves.  
       OBJECTS AND SUMMARY OF THE INVENTION  
       [0008]     It is an object of the present invention to provide a bulk ink delivery system for ink jet printers and the like which maintains a constant ink level and thereby minimizes the chance of ink starvation or flooding at the printing head.  
         [0009]     It is another object of the present invention to provide a bulk ink delivery system for ink jet printers and the like which indicates to the printer operator the status of the delivery system.  
         [0010]     It is a further object of the present invention to provide a bulk ink delivery system for ink jet printers and the like which overcomes the inherent disadvantages of known ink delivery systems.  
         [0011]     In accordance with one form of the present invention, a bulk ink delivery system includes one or more cartridge housings which conform to the shape of the manufacturer&#39;s standard, ink-filled cartridges so that the cartridge housing of the present invention may be substituted for the ink-filled cartridge normally associated with the printer. Inside the housing is situated an ink pump, a reservoir, and a control circuit for operating the ink pump. The ink pump replenishes the ink reservoir in the cartridge housing, and receives ink from one of several external ink bottles, one bottle for each color and one bottle for each cartridge housing. The printing head draws ink from the reservoir, as needed.  
         [0012]     The control circuit for operating the pump includes a high volume primary level sensing switch, which monitors the quantity of ink in the internal reservoir within the cartridge housing. The control circuit is responsive to the primary level sensing switch, which is situated within the internal reservoir, and energizes or deenergizes the pump to add more ink as required to the reservoir in order to maintain a predetermined level of ink within the reservoir. The ink is withdrawn by capillary action or the like from the reservoir by the printing head, as the printing head would normally do with a standard replaceable ink filled cartridge. Thus, a steady supply of ink is provided to the printing head, as required, and the chances of ink starvation or flooding at the printing head is minimized. As a safety precaution, a fail safe or secondary level sensing switch, set to trip at a higher ink volume level than the primary level sensing switch, is provided in the reservoir of each cartridge housing, and is used as a back up switch to stop the pump from operating should the primary level sensing switch fail to deenergize the pump when it reaches its predetermined maximum level.  
         [0013]     An external status indicator unit, which includes a plurality of indicator lights, is viewable to the operator of the printer. The lights indicate the status of the ink delivery system of the present invention, such as when the pump is energized to replenish ink to the internal reservoir for each ink color provided to the printing head.  
         [0014]     These and other objects, features and advantages of the present invention will be apparent from the following detailed description of illustrative embodiments thereof, which is to be read in connection with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]      FIG. 1  is a front perspective view of a bracket which holds a plurality of external bottles of ink, which forms part of the bulk ink delivery system of the present invention.  
         [0016]      FIG. 2  is a front perspective view of a status indicator unit forming part of the bulk ink delivery system of the present invention.  
         [0017]      FIG. 3  is a perspective view of one half of the cartridge housing, illustrating the components which are housed therein, which forms part of the bulk ink delivery system of the present invention.  
         [0018]      FIG. 4  is a schematic diagram of the control circuit and pump which is situated within the cartridge housing of the bulk ink delivery system of the present invention, as well as the circuitry for the status indicator unit of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0019]     Turning initially to  FIG. 1  of the drawings, it will be seen that a bulk ink delivery system for ink jet printers and the like first includes a bracket  2  comprised of a plurality of horizontal arms  4 , adjacent arms  4  being spaced apart from each other to define a space therebetween for hanging between adjacent arms a plurality of ink bottles  6 . Preferably, each bottle  6  is dimensioned to hold one liter of ink. The ink bottles  6  have oppositely and outwardly extending flanges at their upper portions which allow the ink bottles to rest on and in between adjacent horizontal arms  4  of the bracket  2 .  
         [0020]     Each ink bottle  6  is provided to hold a particular color for the printer. Furthermore, each ink bottle  6  includes a tube  8  extending into the interior of the bottle and outwardly therefrom to a particular cartridge housing  10 , such as that shown in  FIG. 3  of the drawings. The ink bottles  6  provide an uninterrupted supply of ink to the printer, through the specially designed ink cartridge housings  10 . The ink bottles  6  are easy to replace and refill, and prevent the ingestion of air pockets into the ink lines, which ensures continuous and worry free printing for hundreds of hours at a time.  
         [0021]      FIG. 3  of the drawings shows one half of a replacement cartridge housing  10  for the printer. Depending upon the manufacturer, each printer has an ink cartridge, or a plurality of ink cartridges, which have particular dimensions. It is envisioned to be within the scope of the present invention to design a replacement cartridge housing  10  for substitution with the original, ink-filled cartridge designed for the particular printer. Accordingly, the dimensions of the housing  10  will vary from printer to printer.  
         [0022]     The cartridge housing  10  of the present invention includes a pump  12 , an ink reservoir  14 , and a pair of level sensing switches  16 ,  18 , such as float switches, which are contained within the ink reservoir  14  of the cartridge housing  10 . Also enclosed is a printed circuit board  20  which contains the electronic circuit (shown in  FIG. 4 ) for driving the pump  12  and illuminating the status indicator lights which are found on the status indicator unit  22  shown in  FIG. 2  of the drawings. There will, of course, be several cartridge housings  10 , one for each color, each replacing an original equipment manufacturer&#39;s ink-filled cartridge for the printer.  
         [0023]     The conduit  8  from a particular ink bottle  6  is provided to a connector  24  on the outside of the cartridge housing  10  and is connected thereto. The input connector  24  is connected to an internal conduit  26  which provides ink from the external ink bottle  6  to the pump  12  and, in particular, the diaphragm portion (i.e., impeller unit) thereof. The pump  12 , with its pump motor driving the diaphragm, when energized, forces the ink out of an exit port in the impeller unit through another conduit  28  and into the internal reservoir  14 , where the delivered ink fills the interior of the reservoir to a particular level.  
         [0024]     First and second level sensing switches  16 ,  18  are provided to ensure that the level of the ink within the internal reservoir  14  is maintained at a predetermined level. The pump  12  will be energized only if the level falls below a threshold lower limit. An ink output conduit  30  is connected to the reservoir  14  at or near its lowest point and communicates with the interior thereof, and is connected to an output connector  32  on another side of the cartridge housing  10 . This output connector  32  mates with another connector of the printer so that the printer may draw by capillary action or the like ink from the bottom of the reservoir  14  of the cartridge housing  10 , as it would do with a conventional ink-filled cartridge which the cartridge housing of the present invention replaces.  
         [0025]     A third conduit  34  is connected interiorly of the cartridge housing  10  between a third connector  35  on a side of the cartridge housing and the reservoir  14 . The third conduit  34  is used as a vent conduit which is connected to the top wall of the reservoir  14  and which communicates with the interior thereof to vent any air and equalize the pressure within the reservoir to the ambient environment.  
         [0026]     The two-level sensing switch system provides a safety backup feature to prevent ink starvation and flooding at the printing head. One level sensing switch  16  is used as the primary control for the operation of the pump  12 , turning it on and off to refill the reservoir  14  as needed, and the other level sensing switch  18  is a back up or safety switch if the first level sensing switch  16  fails.  
         [0027]     Although shown in  FIG. 3 , the ink intake conduit  28  passes through the top of the reservoir  14 , the conduit may be connected to the bottom of the reservoir, below the ink level, in order to minimize agitation and the formation of bubbles in the ink. If the ink intake conduit  28  is connected to the bottom of the reservoir  14 , for example, to a reservoir input port or fitting situated on one of the narrower lateral sides thereof, a short baffle wall (not shown), extending interiorly upwardly in the reservoir from the bottom wall thereof and positioned in horizontal alignment with the reservoir input port connected to the ink intake conduit  28 , may be included. This baffle wall would be further preferably positioned between the reservoir ink input port and the reservoir ink output port or fitting coupled to the ink output conduit  30 , and helps further to minimize agitation and the formation of bubbles in the ink close to the bottom of the reservoir  14 , especially near where the ink is drawn from the reservoir by the printer through the ink output conduit  30 . Also, if it is desired to connect the ink inflow conduit  28  to the top of the reservoir  14 , a stem tube (not shown) extending vertically partially through the interior of the reservoir just short of the bottom of the reservoir or at least below the minimum ink level, may be connected to the top wall of the reservoir at the point that the inflow conduit is connected thereto so that replenishment ink provided to the reservoir will pass through the stem tube and will be discharged therefrom below the level of the ink and further below the lowest level that the level sensing switches  16 ,  18  reside in the interior of the reservoir  14 .  
         [0028]     As further can be seen from  FIG. 3  of the drawings, a printed circuit board  20  which contains the electronic circuitry, as shown in  FIG. 4 , for operating the pump  12  and illuminating the various indicator lights on the separate status indicator unit  22  is situated within the cartridge housing  10 . Electrical wires, such as in a multiple conductor cable (e.g., a multiconductor telephone wire)  36 , are connected to the printed circuit board  20  and carry the signals through the cartridge housing  10  and to the status indicator unit  22 .  
         [0029]     The preferred circuit for operating the pump  12  is shown schematically in  FIG. 4  of the drawings. The circuit shown is for illustrative purposes only, and it is envisioned to be within the scope of the present invention to derive other circuits for operating the pump of each cartridge housing  10 .  
         [0030]     As shown in  FIG. 4 , a voltage (VDC), which is preferably 5.75 volts, is provided to a first contact of a single pole, single throw level sensing switch  18 , which acts as the safety overflow switch, and to the emitter of a PNP transistor Q 1  (preferably, Part No. 2N5400). As will be seen, the transistor Q 1  is used to switch on an overflow red light emitting diode (LED)  38  when overflow conditions arise, if at all. The other contact of the safety overflow level sensing switch  18  is connected to one contact of the second, primary level sensing switch  16 , which is also a single pole, single throw switch, and to the junction of resistors R 3  and R 4 , which form a resistor divider network, as will be seen. The second contact of the safety overflow level sensing switch  18  is also provided through one wire of the multiconductor cable  36  to the anode of a yellow LED  40  situated on the status indicator unit  22 , which is remotely located from the housing cartridge  10  that fits into the printer and is visible to the operator.  
         [0031]     The base of the PNP transistor Q 1  is connected to the opposite end of resistor R 4 , and the collector of the PNP transistor Q 1  is connected through one wire of the multiconductor telephone wire  36  to the anode of the red LED  38 , which when illuminated indicates an overflow condition, which red LED  38  is situated on the status indicator unit  22 .  
         [0032]     The other contact of the primary operational level sensing switch  16  is connected to one contact of the ink pump  12 , which is used to replenish the ink in the reservoir  14 , and is connected through another wire of the multiconductor telephone wire  36  to the anode of a green LED  42  also situated on the status indicator unit  22  of the delivery system. System ground is provided on another wire of the multiconductor telephone wire  36  to the other leg of resistor R 3  and the other contact of the pump  12 . System ground also is connected to one end of a current limiting resistor R 2  and one end of another current limiting resistor R 1 . The other ends of resistors R 2  and R 1  are respectively connected to the cathodes of the yellow LED  40  and the red and green LEDs  38 ,  42 , as shown in  FIG. 4 . Preferably, resistors R 1  and R 2  are 200 ohm resistors, and each of the red, yellow and green LEDs are about 2.1 volt or 2.2 volt LEDs, drawing about 20 milliamperes.  
         [0033]     The operation of the circuit shown in  FIG. 4  will now be described. Normally, the primary operational level sensing switch  16  and the safety overflow level sensing switch  18  are on (i.e., conductive) and, as can be seen from the circuit diagram of  FIG. 4 , are connected in series to provide 5.75 volts (the preferred voltage) through the safety level sensing switch  18  and the operational level sensing switch  16  to the pump  12 . The pump  12  is driven to pump ink from a respective ink bottle  6  into the reservoir  14  at a controlled rate. The pump  12  is preferably a 12 volt pump, Model No. NF10, manufactured by KNF Flotos of Sweden, and is driven only at 5.75 volts to decrease the flow rate of ink into the reservoir  14  and to prevent agitation of the ink and formation of bubbles within the reservoir. With both level sensing switches on, which means that the ink level in the reservoir  14  is below a threshold level, ink is supplied to the reservoir to increase the level of the ink therein.  
         [0034]     As can be seen from the circuit diagram of  FIG. 4 , when the pump  12  is on, voltage is supplied to the yellow LED  40  to illuminate it, which indicates that the system is functioning properly for that particular cartridge housing  10 . Also, with both level sensing switches  16 ,  18  on, power is provided to the green LED  42  to indicate that pumping of ink is occurring with respect to that particular cartridge housing  10 .  
         [0035]     When the level of the ink in the reservoir  14  reaches a particular threshold level, the operational level sensing switch  16  will open. This breaks the connection to the 5.75 volt power supply, and the pump  12  stops running. Since the operational level sensing switch  16  now opens, no voltage is provided to the green LED  42 , and the LED will de-illuminate, thus indicating that pumping has stopped for this particular cartridge housing  10 .  
         [0036]     For the conditions when 1) both level sensing switches  16 ,  18  are on, and 2) when the operational level sensing switch  16  is off but the overflow level sensing switch  18  is on, the PNP transistor Q 1  will be back biased and, therefore, the red LED  38 , which indicates an overflow condition, will remain off.  
         [0037]     As the printer draws ink from the cartridge housing  10  and the level in the respective reservoir  14  falls below the threshold level, the primary operational level sensing switch  16  will again turn on to allow current to pass therethrough to the pump  12 , energizing the pump so that the pump may refill the reservoir  14  with ink, and energizing the green LED  42  in the status indicator unit  22  to indicate that pumping for that particular cartridge housing  10  is occurring.  
         [0038]     As mentioned previously, the safety overflow level sensing switch  18  is provided for safety purposes in the event that the operational level sensing switch  16  becomes jammed or does not open properly when the ink level within the reservoir  14  reaches the threshold level. The contact for the safety overflow level sensing switch  18  is at a higher level than the contact of the operational level sensing switch  16  and, therefore, sets an overflow threshold level in the reservoir  14 . The level of the ink in the reservoir should cause the operational level sensing switch  16  to open at the normal ink threshold level. However, if for some reason this does not occur and the pump  12  remains energized, the safety overflow level sensing switch  18  will open when the ink level in the reservoir reaches the overflow threshold level. When the safety overflow level sensing switch  18  opens, it breaks the circuit providing power to the pump  12  and deenergizes the pump. It also breaks the circuit to the green LED  42 , which now unlit indicates that pumping has stopped for this particular cartridge housing  10 . It further breaks the circuit connection to the yellow LED  40 , which no longer illuminates to indicate that the system is functioning properly.  
         [0039]     With the safety overflow level sensing switch  18  now open, the PNP transistor Q 1  is forward biased through the 5.75 volts provided to its emitter and through the resistor divider network on its base, and turns on to switch on the red LED  38  located at the status indicator unit  22  to indicate that there is an overflow condition for this particular cartridge housing  10 . Preferably, resistor R 4  is 3.3K ohms, and resistor R 3  is 1K ohms. Resistors R 3  and R 4  act as a voltage divider, but also provide proper biasing for the transistor Q 1  to turn it on. The voltage at the junction of resistors R 3  and R 4  is lower than that required to turn on the yellow LED  40  and the green LED  42  or to drive the pump  12 . Thus, the green pumping LED  42  and the yellow system function LED  40  remain off, and no further ink is supplied to the reservoir  14  of the particular cartridge housing  10  when in the overflow mode. However, the red LED  38  illuminates to indicate an overflow condition to the operator. When the overflow condition is corrected, the safety overflow level sensing switch  18  will again close (i.e., its normal conductive condition), and normal operation of the pump circuit will resume.  
         [0040]     In an alternative embodiment of the present invention, and as shown in  FIG. 4 , a timing circuit  44  may be included to interrupt the operation of the pump  12  if the pump has been running continuously for a predetermined period of time. More specifically, connected in series between the pump  12  and the operational level sensing switch  16  may be a single pole, single throw electronic switch  46  which is controlled by a timing circuit  44 , such as an NE555 timer, for example. The electronic switch  46  may be a switching transistor circuit, or a relay controlled by a transistor drive circuit, or the like. The timing circuit  44  may be triggered whenever the operational level sensing switch  16  turns on, and may be set to provide a two minute pulse to the electronic switch  46 , turning the switch on for no more than two minutes, for example. After two minutes has elapsed, the output pulse from the timing circuit  44  ends, causing the electronic switch  46  to open. The timing circuit  44  will be retriggerable every time the operational level sensing switch  16  closes and, because the electronic switch  46  is in series with the operational level sensing switch  16 , the operational level sensing switch will still control the energization of the pump  12  during the two minute window provided by the timing circuit  44  and the electronic switch  46 . If the pump  12  remains running for more than two minutes, the electronic switch  46  will break the circuit to the pump to deenergize it.  
         [0041]     It is also envisioned that the timing circuit  44  can interrupt the power circuit to the pump  12  if more than a predetermined period of time, such as two minutes, has elapsed during a single continuous pumping cycle. The timing circuit  44 , activated upon closure of the operational level sensing switch  16 , would cause a latching circuit  47 , such as a bistable multivibrator or flip flop, connected thereto and controlling the electronic switch  46  to latch the switch in an open condition, thus breaking the circuit to the pump  12 , if the operational level sensing switch  16  remains on for more than two minutes. The latching circuit  47  could also drive and be connected to the anode of another LED, such as a blue LED  48 , to indicate that an error has occurred in that the pump  12  was running continuously for more than a predetermined amount of time. The pump  12  will, of course, stop functioning when the electronic switch  46  opens. The blue LED  48  will indicate to the operator that a malfunction has occurred, or there is something wrong with the pump  12  of that particular cartridge housing  10 . A switch (not shown) may be provided to the reset input of the latching circuit and may be activated by the operator after he has inspected the cartridge housing  10  and the operation of the pump  12  and the control circuit for the pump.  
         [0042]     The timing circuit  44  provides another safety feature to the ink delivery system of the present invention. It ensures that the pump  12  will not run continuously for more than a predetermined period of time, thus further preventing an overflow condition.  
         [0043]     The status indicator unit  22  is illustrated by  FIG. 2  of the drawings. It basically includes a power supply  50 , which generates 5.75 volts DC (direct current), which is provided through the multiconductor cable  36  to each of the cartridge housings  10 . The status indicator unit  22  also includes a plurality of modular connectors  52 , one for each cartridge housing  10 , which receives the modular jack connector  54  of each multiconductor cable  36  from each cartridge housing. The female connectors  52  which receive the modular jack connectors  54  are wired to the power supply  50  and to respective red, yellow and green (and optionally blue) LEDs  38 ,  40 ,  42 ,  48  for each of the cartridge housings  10 . If desired, a color coded label  56  may be positioned next to each row of LEDs associated with a respective ink bottle  6  so as to identify the particular cartridge housing connected to a corresponding ink bottle and associated with a particular row of colored LEDs.  
         [0044]     The operator may easily view the rows and columns of LEDs  38 ,  40 ,  42 ,  48  to determine the operational status of each cartridge housing  10  and whether such is functioning properly. Also, because the ink bottles  6  are viewable to the user, and are at least partially translucent or transparent, the operator may easily determine whether a particular ink bottle must be replaced.  
         [0045]     The bulk ink delivery system of the present invention minimizes any interruption in the operation of the ink jet printer or the like. The status of each cartridge housing  10  is indicated by its associated LEDs  38 ,  40 ,  42 ,  48 , which are viewable remotely by the operator on the status indicator unit  22 . Ink starvation and overflow conditions are virtually eliminated. The redundancy in the level sensing switches  16 ,  18  addresses situations where the primary operational level sensing switch  16  fails. The level of ink in the separate ink bottles  6  is viewable by the operator so that he may easily replace or refill bottles, as required, with little or no interruption to the printing operation.  
         [0046]     Because the cartridge housings  10  have the same dimensions, and configurations, and placement of the connectors  24 ,  32 ,  36  as the original equipment, ink-filled cartridges they replace, the operator can easily substitute the cartridge housing  10  of the present invention with the original equipment ink-filled cartridges.  
         [0047]     It should be noted that  FIG. 3  shows one end of the multiconductor cable  36  passing through a grommet lining an opening formed through the thickness of the wall of the cartridge housing  10 , with the individual conductors being hard-wired to the printed circuit board  20 . An alternative to this would be to have modular jack connectors  54  at both ends of the multiconductor cables  36  so that the jack connectors mate with female connectors  52  not only on the status indicator unit  22 , as shown in  FIG. 2 , but also on the ink cartridge housings  10 , in place of the multiconductor cable  36  passing through the grommeted housing opening. The female connectors  52  on the cartridge housings  10  would be wired directly to the printed circuit boards  20 . In this way, the multiconductor cables  36  may be separable from the cartridge housings  10  and may be used with any of the cartridge housings, reused if a cartridge housing is replaced, or replaced by a different cable independently of the cartridge housing.  
         [0048]     Although illustrative embodiments of the present invention have been described herein with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments, and that various other changes and modifications may be effected therein by one skilled in the art without departing from the scope or spirit of the invention.