Abstract:
A system, including an ink supply system configured to supply ink to a printhead; and an autopurge unit configured to automatically clean the printhead. The autopurge unit includes a solvent supply in fluid communication with a solvent line, a solenoid housing, and a waste container. The solenoid housing includes a first solenoid assembly disposed within an ink line, wherein the ink line is in fluid communication with the ink supply and a first outlet that is configured to be in fluid communication with the printhead; and a second solenoid assembly disposed within a solvent line. The waste container is in fluid communication with a waste delivery line having a waste inlet. The waste inlet is configured to be in fluid communication with a waste line that is in communication with the printhead so that fluid waste from the printhead is deposited into the waste container.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     Embodiments of the present invention generally relate to an inkjet printer, and more particularly, to an inkjet printer having an autopurge system configured to automatically clean a printhead.  
         [0002]     Drop-on-demand inkjet printers include a printhead having a binary array having a large number of print orifices. During printing, ink is ejected through particular orifices based on the nature of a character to be printed on a suitable medium. Ink is not ejected through every orifice at all times during a printing process. Rather, only select orifices are utilized at any one time depending on the nature of the character to be printed. Generally, drop-on-demand inkjet printers differ from continuous inkjet printers, in which a constant stream of drops are passed between charged electrodes, because ink is not ejected through all of the orifices during a particular printing process.  
         [0003]     Due to the fact that ink is not ejected through all of the orifices during a printing process, the orifices that are less frequently used may accumulate dust, dirt, dried ink, and other waste materials over time. Certain orifices may become crusted over, restricted, or blocked because of infrequent use, or simply because the printing system may be idle for an extended period of time. Additionally, the printface, in general, may also accumulate debris, such as dust, dirt, paper debris, and the like.  
         [0004]     In order to purge the orifices and printhead of impurities and other waste products, the printhead is typically manually cleaned. For example, the printhead may be sprayed with a cleaning solvent, and then wiped off.  
         [0005]     Further, some printing systems automatically purge the orifices of waste materials by periodically passing ink therethrough, in order to break up obstructions within the orifices. In general, however, a user still needs to collect the ink and waste materials after they have been passed through the orifices. Such a process, however, is inefficient and time-consuming.  
         [0006]     Thus, a need exists for an efficient system and method of purging a printhead of impurities. Further, a need exists for a self-contained waste removal and collection system.  
       SUMMARY OF THE INVENTION  
       [0007]     Certain embodiments of the present invention provide an inkjet printing system that includes a printhead, a solvent supply, and a first solenoid assembly. The printhead has an orifice plate and a solvent port disposed above the orifice plate. The printhead also includes a vacuum port disposed below the orifice plate. The vacuum port is configured to collect solvent waste fluid.  
         [0008]     The solvent supply is in fluid communication with the solvent port through a solvent supply line. The first solenoid assembly is disposed within the solvent supply line, and is engaged to close a portion of the solvent supply line such that solvent within the solvent supply line that is downstream from the first solenoid assembly is pulsed through the solvent supply line. The solvent that is pulsed through the solvent supply line pulses out the solvent port and passes over the orifice plate, thereby removing waste materials from the orifice plate to form solvent waste fluid.  
         [0009]     The inkjet printing system may also include an ink supply in fluid communication with the orifice plate through an ink supply line, and a second solenoid assembly disposed within the ink supply line. The second solenoid assembly is engaged to close a portion of the ink supply line such that ink within the ink supply line that is downstream from the second solenoid assembly is pulsed through the ink supply line. The ink that is pulsed through the ink supply line pulses out orifices within the orifice plate. The ink pulsed through the orifices removes ink waste materials from the orifices, thereby forming ink waste fluid that passes over the orifice plate.  
         [0010]     The system also includes a waste removal line and a waste container. The waste removal line is in fluid communication with the vacuum port and the waste container such that the solvent and ink waste fluids pass from the vacuum port to the waste container by way of the waste removal line.  
         [0011]     Certain embodiments of the present invention also provide a system including an ink supply system configured to supply ink to a printhead, and an autopurge unit configured to automatically clean the printhead. The autopurge unit includes a solvent supply in fluid communication with a solvent line, a solenoid housing, and a waste container.  
         [0012]     The solenoid housing includes a first solenoid assembly disposed within an ink line and a second solenoid assembly disposed within a solvent line. The ink line is in fluid communication with the ink supply and a first outlet that is configured to be in fluid communication with the printhead; and a second solenoid assembly disposed within a solvent line. The first and second solenoid assemblies are configured to constrict proximate portions (i.e., portions that are proximate the first and second assemblies) of the ink and solvent lines, respectively.  
         [0013]     The waste container is in fluid communication with a waste delivery line having a waste inlet. The waste inlet is configured to be in fluid communication with a waste line that is in communication with the printhead so that fluid waste from the printhead is deposited into the waste container. The system also includes a vacuum adapted to draw the fluid waste into the waste container.  
         [0014]     Certain embodiments of the present invention also provide a method of automatically cleaning a printhead of an inkjet printer. The method includes engaging a first solenoid assembly to constrict a solvent supply line, pulsing solvent through a portion of the solvent supply line that is downstream from the first solenoid assembly due to said engaging, and running the solvent over an orifice plate of the printhead through a solvent port that is in fluid communication with the solvent supply line, wherein the running removes debris from the orifice plate. The method may also include opening a downstream check valve due to the engaging step so that solvent may pass through the downstream check valve, and closing an upstream check valve due to the engaging step so that solvent may not pass through the upstream check valve.  
         [0015]     The method also includes suctioning the solvent and debris into a vacuum port located below the orifice plate, and passing the solvent and debris into a waste removal line having a first end that is fluidly connected to the vacuum port and a second end that is fluidly connected to a waste container, wherein the solvent and debris are deposited into the waste container.  
         [0016]     Additionally, the method may include engaging a second solenoid assembly to constrict an ink supply line, pulsing ink through a portion of the ink supply line that is downstream from the second solenoid assembly due to said engaging; and pulsing ink through orifices of the orifice plate that is in fluid communication with the ink supply line so that waste is removed from the orifices. The ink is suctioned into the vacuum port.  
     
    
     BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS  
       [0017]      FIG. 1  illustrates an isometric view of an autopurge ink system, according to an embodiment of the present invention.  
         [0018]      FIG. 2  illustrates a side view of an autopurge ink system, according to an embodiment of the present invention.  
         [0019]      FIG. 3  illustrates an isometric view of portions of a printing system, according to an embodiment of the present invention.  
         [0020]      FIG. 4  illustrates an isometric view of a printhead and connection line, according to an embodiment of the present invention.  
         [0021]      FIG. 5  illustrates an isometric view of a printface of a printhead, according to an embodiment of the present invention.  
         [0022]      FIG. 6  illustrates a schematic representation of a printing system, according to an embodiment of the present invention.  
         [0023]      FIG. 7  illustrates an isometric view of an autopurge ink system, according to an alternative embodiment of the present invention.  
         [0024]      FIG. 8  illustrates a front view of a printface of a printhead, according to an alternative embodiment of the present invention. 
     
    
       [0025]     The foregoing summary, as well as the following detailed description of certain embodiments of the present invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there is shown in the drawings, certain embodiments. It should be understood, however, that the present invention is not limited to the arrangements and instrumentalities shown in the attached drawings.  
       DETAILED DESCRIPTION OF THE INVENTION  
       [0026]      FIG. 1  illustrates an isometric view of an autopurge ink system  10 , according to an embodiment of the present invention. The system  10  may be used with a drop-on-demand inkjet printer. The system  10  includes an ink supply system  12  mounted on an autopurge unit  14 . The ink supply system  12  includes an ink bottle  16  in communication with an ink reservoir  18 , such that ink passes from the ink bottle  16  into the ink reservoir  18 . The autopurge unit  14  includes a solenoid housing  20  connected to a ink supply system support housing  22 . A solvent supply bottle  24  and a waste container  26  are removably mounted to the ink supply system support housing  22 . For example, the solvent supply bottle  24  and the waste container  26  may threadably engage corresponding reciprocal threaded engagement ports (not shown) located on said ink supply system support housing  22 . Thus, the solvent supply bottle  24  and the waste container  26  may be threaded onto and removed from the ink supply system support housing  22 .  
         [0027]     In operation, ink flows from the ink supply system  12  into the autopurge system  14  through appropriate tubing (not shown). The ink flows through the solenoid housing  20  and into tubing (not shown) that allows the ink to pass out of the autopurge ink system  10 . Similarly, solvent passes from the solvent supply bottle  24  into tubing (not shown) through the ink supply support housing  22  and into the solenoid housing  20 . The solvent then passes out of the autopurge system  10  through appropriate tubing (not shown).  
         [0028]      FIG. 2  illustrates a side view of the autopurge ink system  10 . As shown in  FIG. 2 , ink passes into the ink supply support housing  22  by way of an ink supply line  27 , including tubing, that passes into the solenoid housing  20 . The ink supply line  27  is in fluid communication with the ink supply system  12 . A solenoid assembly  29  is disposed within the ink supply line  27 , and is configured to squeeze, crimp, crush, pinch, or otherwise constrict the ink supply line  27  in order to restrict ink flow from a pre-entry position  28  to an exit position  30 . The solenoid assembly  29  may be a solenoid-operated pinch valve, or any other type of device that is configured to constrict or squeeze the ink supply line  27 . Additionally, when the solenoid assembly  29  is actuated or engaged, thereby constricting the ink supply line  27 , ink in the ink supply line  27  that has already passed through the solenoid assembly  29  is pushed at the exit position  30  through the remaining portion of the ink supply line  27  in the direction of arrow A.  
         [0029]     Check valves may be disposed within the ink supply line  27  before and after the solenoid assembly  29 . One check valve may be disposed within the ink supply line  27  upstream of the solenoid assembly  29 , while the other check valve may be disposed downstream the solenoid assembly  29 . For example, the downstream check valve may be disposed within an ink line within a printhead. The check valves within the ink supply line may be operated by way of a manual purge bulb to create a pumping action within the ink line.  
         [0030]     Solvent passes into the solenoid housing  20  through the ink supply support housing  22  by way of a solvent supply line  32 , which includes tubing. The solvent supply line  32  is in fluid communication with the solvent bottle  16  (shown in  FIG. 1 ). An upstream check valve  34  is disposed within the solvent supply line  32  upstream from a solenoid assembly  36 . The solenoid assembly  36  may be a solenoid-operated pinch valve, or any other such device that is configured to constrict or squeeze the solvent supply line  32 . A downstream check valve  38  is disposed within the solvent supply line  32  downstream from the solenoid assembly  36 . When the solenoid assembly  36  is actuated or engaged to constrict or squeeze the solvent supply line  32 , solvent flow from a pre-entry position  40  to an exit position  42  is restricted. Additionally, upon actuation of the solenoid assembly  36 , the upstream check valve  34  closes and the downstream check valve  38  opens up and allows the solvent to pulse or flow forward in the direction of arrow B. When the solenoid assembly  36  is not actuated, the upstream check valve  34  opens and allows solvent to fill the solvent supply line  32  up to the downstream check valve  38 , which is closed, thereby restricting solvent from flowing therethrough. When the solenoid assembly  36  is actuated, thereby squeezing the solvent supply line  32  proximate the solenoid assembly  36  and forcing the downstream check valve  38  open, the fluid filled in the solvent supply line  32  from the solenoid assembly  36  to the downstream check valve  38  flows through the downstream check valve  38  in the direction of arrow B. Alternatively, the solvent supply line  32  may not include the check valves  34  and  38 .  
         [0031]      FIG. 3  illustrates an isometric view of portions of a printing system  44 , according to an embodiment of the present invention. The printing system  44  includes a central processing unit (CPU)  46  in electrical communication with the printing system  44 , including the autopurge ink system  10 . The CPU  46  controls the operation, for example the timing, of the printing system  44 . A connection line  48  is connected to the autopurge ink system  10  and bundles and houses various tubing and electrical wiring from the autopurge ink system  10  to a printhead  50 . The connection line  48  includes a flexible tube  51  that houses an ink line  52  having a tie wrap  53  and an ink line fitting  55  located at a distal end  57  of the ink line  52 . The ink line  52  also includes a proximal end (not shown) that is integrally formed with, or connected to, the ink supply line  27  (shown in  FIG. 2 ). Further, the connection line  48  includes a low ink alarm cable  54 , a waste line  56 , a solvent line  58  having an end (not shown) that is integrally formed or connected to the solvent supply line  32 , a photocell link cable  60 , and a photocell extension cable  62 . The waste line  56  includes a proximal end (not shown) that is integrally formed with, or connected to appropriate tubing (not shown) within the autopurge system  10  that is in fluid communication with the waste container  26 . The connection line  48  may be housed within a rigid tube  64 .  
         [0032]      FIG. 4  illustrates an isometric view of the printhead  50  and a distal end  66  of the connection line  48 . The printhead  50  includes a connection interface  68  and a printface  70 . The connection interface  68  includes an ink fitting  72  having a quick disconnect button  74 , a waste connection  76 , a low ink alarm jack  78 , a photocell connector  80 , and a solvent connection line  82 .  
         [0033]     As shown in  FIG. 4 , the distal end  57  of the ink line  52  mates with the ink fitting  72 , thereby providing a fluid connection for ink to pass from the autopurge system  10  to the printhead  50  through the connection line  48 . The printhead  50  also includes appropriate tubing (not shown) that allows ink to pass from the ink fitting  72  to the printface  70 .  
         [0034]     The low ink alarm cable  54  mates with the low ink alarm jack  78 , thereby providing a connection between the printhead  50  and the autopurge system  10 . Electrical signals sensed by a low ink sensing device (not shown) positioned within the printing system  44  are passed through the low ink alarm jack  78  through the low ink alarm cable  54 , and eventually onto the CPU  46  (shown in  FIG. 3 ) for appropriate processing  
         [0035]     The waste line  56  connects to the waste connection  76 . As such, waste fluid may pass from the printhead  50  to the waste line  56  through the waste connection  76 . The waste fluid then passes from the waste line  56  to appropriate tubing (not shown) positioned within the autopurge system  10  (shown with respect to  FIGS. 1-3 ) and into the waste container  26  (shown, e.g., in  FIG. 3 ). The autopurge system  10  may include a vacuum pump that suctions waste fluid from the printhead  50  into the waste container  26 , as described above.  
         [0036]     The solvent line  58  connects to the solvent connection line  82  of the printhead  50 . Thus, solvent may pass from the autopurge system  10  to the printhead  50  through the connection of the solvent line  58  and the solvent connection line  82 . Solvent passes through appropriate tubing (not shown) within the printhead  50  to the printface  70 .  
         [0037]     The photocell link  60  connects to the photocell connector  80 . Additionally, the photocell extension cable  62  is configured to mate with a reciprocal connector  84  of a photocell  86 .  
         [0038]      FIG. 5  illustrates an isometric view of the printface  70  of the printhead  50 . The printface  70  includes an ink orifice plate  88  having an ink orifice array  90 , a solvent port  92 , and a vacuum port  94 . During printing, ink pulses through orifices within the ink orifice array  90  onto a suitable medium at appropriate locations and times, which are determined by the nature of the character(s) to be printed. That is, the printhead  50  is utilized with a drop-on-demand printing system.  
         [0039]     Ink may run or drool down the orifice plate  88  in order to clean the orifices located within orifice plate  88 . Ink runs, or drools, down the orifice plate  88  due to gravity and the suctioning action of the vacuum port  94 . The vacuum port  94  is in fluid communication with the waste line  56  (shown in  FIGS. 3 and 4 ), so that excess ink may be vacuumed through the waste line  56  to the autopurge system  10 .  
         [0040]     Additionally, solvent may pulse from the solvent port  92  and run or droll over the orifice plate  88 . The solvent that drools over the orifice plate  88  collects waste materials, such as dust, paper debris, dry ink, and the like, and is collected at vacuum port  94 . That is, waste materials, whether they are picked up by ink or solvent that drools over the orifice plate  88 , are suctioned into the waste line  56  by way of the vacuum port  94 .  
         [0041]      FIG. 6  illustrates a schematic representation of the printing system  44 . Ink is supplied to the printhead  50  through the ink supply line  27  in the direction of arrows A. The solenoid assembly  29  is engaged to contract or squeeze the ink supply line  27  in conjunction with check valves, thereby squeezing ink through the ink supply line  27  downstream from the solenoid assembly  29 , and out orifices within the ink orifice array  90 . Because the ink is squeezed through the ink supply line  27 , the ink pulses out of the orifices of the ink orifice array  90  and drools or runs over the ink orifice plate  88 . As the ink picks up waste materials on the orifice plate array  88 , it drools down the orifice plate  88  in the direction of arrow D, until it is suctioned into the vacuum port  94 .  
         [0042]     Similarly, solvent passes through the solvent supply line  32  onto the printhead  50  through the action of the solenoid assembly  36 . As the solenoid assembly  36  is engaged, it constricts the solvent supply line  32 . Consequently, the downstream check valve  38  is forced open and solvent within the solvent supply line  32  up to that point is squeezed through the portion of the solvent supply line  32  that is downstream from the downstream check valve  38 , and into the solvent port  92 . When the solenoid assembly  36  is engaged, the upstream check valve  34  closes thereby precluding solvent from passing therethrough. Upon disengagement of the solenoid assembly  36 , the downstream check valve  38  closes, thereby preventing solvent from passing therethrough, while the upstream check valve  38  opens, thereby allowing solvent to fill the solvent supply line  32  up to the downstream check valve  38 .  
         [0043]     As solvent is squeezed through the solvent supply line  32  in the direction of arrows B, the solvent is passed to the solvent port  92 . The squeezing action of the solenoid assembly  36  causes solvent to pulse out of the solvent port  92 . As the solvent pulses through the solvent port  92 , it drools or runs down the orifice plate  88  in the direction of arrow E, thereby collecting waste materials. The solvent and collected waste materials are then suctioned into the vacuum port  94 .  
         [0044]     In general, ink is pulsed through the orifices of the orifice array  90  in an ink waste removal process as described above in order to remove crusted materials, dried ink, and the like from the orifice plate  88 . Further, solvent is pulsed through the solvent port  92  to drool down the orifice plate  88  in a solvent waste removal process, as described above, in order to remove external debris, such as paper, dust, ink deposits, and the like. Waste material, including ink, solvent, and collected waste products (such as dried ink deposits, dust, and the like) are suctioned through the waste line  56  and into the waste container  26  by way of a vacuum  96 . The vacuum  96  may be housed within the autopurge system  10 , or it may optionally be separate and distinct therefrom.  
         [0045]     As discussed above, during a cleaning process, ink and solvent drool, or run, over the orifice plate  88  in order to collect and/or remove waste materials therefrom. The ink and solvent, however, do not spit or jet from the orifice plate  88 . In general, ink is pulsed through the orifices of the orifice array  90  in order to clean the orifices of minor debris. The ink and minor debris drool over the orifice plate  88  and are suctioned into the vacuum port  92 . Additionally, solvent is pulsed through the solvent port  92  to wash excess ink and other debris from the orifice plate  88  as it drools over the orifice plate  88 . The waste material that is suctioned into the vacuum port  94  is then collected in the waste container  26 .  
         [0046]     The CPU  46  or other suitable controller may be programmed to clean the orifice plate  88  through the ink waste removal process and/or the solvent waste removal process, as described above. In particular, the CPU  46  may direct only an ink waste removal process, or a solvent waste removal process at any one time. Alternatively, both processes may be performed simultaneously.  
         [0047]      FIG. 7  illustrates an isometric view of an autopurge ink system  100 , according to an alternative embodiment of the present invention. The autopurge ink system  100  includes ink supply system  12  mounted to a side of, instead of over, the autopurge unit  14 . Overall, the autopurge unit  14  and the ink supply system  12  may be oriented in various configurations. Operation of the autopurge ink system  100  is similar to that described above with respect to the autopurge unit  10 .  
         [0048]      FIG. 8  illustrates a front view of a printface  102  of a printhead  104 , according to an alternative embodiment of the present invention. The printface  102  includes an ink orifice plate  106  having an ink orifice array  108 , a solvent port  110 , and a vacuum port  112 . In general, the printhead  104  is similar to the printhead  50 , except that vacuum port  112  is wider and generally larger than the vacuum port  94  shown, for example, in  FIG. 5 . As such, the vacuum port  112  is capable of receiving large debris build-up, and is less likely to smear ink on a passing substrate.  
         [0049]     Embodiments of the present invention provide an efficient system and method of purging a printhead of impurities. In particular, certain embodiments of the present invention provide a self-contained waste removal and collection system. Further, the solenoid assemblies provide a system and method of pulsing ink and solvent to the printhead, without the need for expensive fluid flow systems and the like. Additionally, embodiments of the present invention provide a system for automatically purging and cleaning an array of a drop-on-demand printer.  
         [0050]     While the invention has been described with reference to certain embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.