Patent Publication Number: US-8118408-B2

Title: Flow through dispenser having different cross-sectional areas

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     Reference is made to commonly-assigned, U.S. patent application Ser. No. 12/494,331, entitled “FLOW THROUGH DROP DISPENSER INCLUDING POROUS MEMBER”, Ser. No. 12/494,341, entitled “FLOW THROUGH DISPENSER INCLUDING TWO DIMENSIONAL ARRAY”, Ser. No. 12/494,343, entitled “FLOW THROUGH DISPENSER INCLUDING DIVERTER COOLING CHANNEL”, Ser. No. 12/494,346, entitled “FLOW THROUGH DISPENSER INCLUDING IMPROVED GUIDE STRUCTURE”, and Ser. No. 12/494,350, entitled “LIQUID DIVERTER FOR FLOW THROUGH DROP DISPENSER”, all filed concurrently herewith. 
     FIELD OF THE INVENTION 
     This invention relates generally to the field of fluid dispensers and, in particular, to flow through liquid drop dispensers that eject on demand a quantity of liquid from a continuous flow of liquid. 
     BACKGROUND OF THE INVENTION 
     Traditionally, inkjet printing is accomplished by one of two technologies referred to as “drop-on-demand” and “continuous” inkjet printing. In both, liquid, such as ink, is fed through channels formed in a print head. Each channel includes a nozzle from which droplets are selectively extruded and deposited upon a recording surface. 
     Drop on demand printing only provides drops (often referred to a “print drops”) for impact upon a print media. Selective activation of an actuator causes the formation and ejection of a drop that strikes the print media. The formation of printed images is achieved by controlling the individual formation of drops. Typically, one of two types of actuators is used in drop on demand printing—heat actuators and piezoelectric actuators. With heat actuators, a heater, placed at a convenient location adjacent to the nozzle, heats the ink. This causes a quantity of ink to phase change into a gaseous steam bubble that raises the internal ink pressure sufficiently for an ink droplet to be expelled. With piezoelectric actuators, an electric field is applied to a piezoelectric material possessing properties causing a wall of a liquid chamber adjacent to a nozzle to be displaced, thereby producing a pumping action that causes an ink droplet to be expelled. 
     Continuous inkjet printing uses a pressurized liquid source that produces a stream of drops some of which are selected to contact a print media (often referred to a “print drops”) while other are selected to be collected and either recycled or discarded (often referred to as “non-print drops”). For example, when no print is desired, the drops are deflected into a capturing mechanism (commonly referred to as a catcher, interceptor, or gutter) and either recycled or discarded. When printing is desired, the drops are not deflected and allowed to strike a print media. Alternatively, deflected drops can be allowed to strike the print media, while non-deflected drops are collected in the capturing mechanism. 
     Printing systems that combine aspects of drop on demand printing and continuous printing are also known. These systems, often referred to a flow through liquid drop dispensers, provide increased drop ejection frequency when compared to drop on demand printing systems without the complexity of continuous printing systems. As such, there is an ongoing effort to increase the reliability and performance of flow through liquid drop dispensers. 
     SUMMARY OF THE INVENTION 
     According to one feature of the present invention, a liquid dispenser includes a liquid supply channel including an exit having a cross sectional area, a liquid return channel, and a liquid dispensing channel including a cross sectional area and an outlet opening. The outlet opening includes an end that is adjacent to the liquid return channel. The cross sectional area of a portion of the liquid dispensing channel that is located at the end of the outlet opening is greater than the cross sectional area of the exit of the liquid supply channel. A liquid supply provides liquid under pressure from the liquid supply channel through the liquid dispensing channel to the liquid return channel. A diverter member is selectively actuatable to divert a portion of the liquid toward outlet opening of the liquid dispensing channel. 
     According to another feature of the present invention, a method of printing includes providing a liquid dispenser including a liquid supply channel including an exit, the exit having a cross sectional area, a liquid dispensing channel including an outlet opening, the outlet opening including an end that is adjacent to the liquid return channel, liquid dispensing channel having a cross sectional area, the cross sectional area of a portion of the liquid dispensing channel that is located at the end of the outlet opening being greater than the cross sectional area of the exit of the liquid supply channel, and a liquid return channel; providing liquid under pressure from the liquid supply channel through the liquid dispensing channel to the liquid return channel; and selectively actuating a diverter member to divert a portion of the liquid toward outlet opening of the liquid dispensing channel. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the detailed description of the example embodiments of the invention presented below, reference is made to the accompanying drawings, in which: 
         FIG. 1  is a schematic cross sectional view of an example embodiment of a liquid dispenser made in accordance with the present invention; 
         FIG. 2  is a schematic cross sectional view of another example embodiment of a liquid dispenser made in accordance with the present invention; 
         FIGS. 3(A) and 3(B)  are schematic cross sectional views of another example embodiment of a liquid dispenser made in accordance with the present invention; 
         FIGS. 4(A) through 4(H)  are schematic cross sectional views of additional example embodiments of liquid dispensers made in accordance with the present invention; 
         FIGS. 5(A) through 5(C)  are schematic cross sectional views of additional example embodiments of liquid dispensers made in accordance with the present invention; 
         FIG. 6  is a schematic cross sectional view of another example embodiment of a liquid dispenser made in accordance with the present invention; 
         FIGS. 7(A) through 7(E)  are additional schematic cross sectional views of example embodiments of liquid dispensers made in accordance with the present invention; 
         FIGS. 8(A) through 8(D)  are additional schematic cross sectional views of example embodiments of liquid dispensers made in accordance with the present invention; 
         FIGS. 9(A) through 9(F)  are additional schematic cross sectional views of example embodiments of liquid dispensers made in accordance with the present invention; and 
         FIGS. 10(A) through 10(C)  are additional schematic cross sectional views of example embodiments of liquid dispensers made in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present description will be directed in particular to elements forming part of, or cooperating more directly with, apparatus in accordance with the present invention. It is to be understood that elements not specifically shown or described may take various forms well known to those skilled in the art. In the following description and drawings, identical reference numerals have been used, where possible, to designate identical elements. 
     The example embodiments of the present invention are illustrated schematically and not to scale for the sake of clarity. One of the ordinary skills in the art will be able to readily determine the specific size and interconnections of the elements of the example embodiments of the present invention. 
     As described herein, the example embodiments of the present invention provide a liquid dispenser, often referred to as a printhead, that is particularly useful in digitally controlled inkjet printing devices wherein drops of ink are ejected from a printhead toward a print medium. However, many other applications are emerging which use inkjet printheads to emit liquids (other than inks) that need to be finely metered and deposited with high spatial precision. As such, as described herein, the terms “liquid” and “ink” refer to any material that can be ejected by the liquid dispenser described below. 
     Referring to  FIG. 1 , an example embodiment of a liquid dispenser  10  according to the present invention is shown. Liquid dispenser  10  includes a liquid supply channel  11  that is in fluid communication with a liquid return channel  13  through a liquid dispensing channel  12 . Liquid dispensing channel  12  includes a diverter member  20 . Liquid supply channel  11  also includes an exit area  21 . 
     Liquid dispenser  10  of the present invention does not include a nozzle like conventional flow through liquid dispensing devices. Instead, liquid dispensing channel  12  includes an outlet opening  26 , defined by a beginning  18  and an ending  19 , that opens directly to atmosphere. As such, liquid ejected by liquid dispenser of the present invention does not need to travel through the nozzle of conventional devices which helps to reduce the likelihood of the nozzle area of the device being contaminated or clogged. The beginning  18  of outlet opening  26  also at least partially defines the exit  21  of liquid supply channel  11 . 
     Liquid dispenser  10  also includes a liquid supply  24  that provides liquid  25  to liquid dispenser  10 . During operation, liquid  25 , pressurized by a regulated pressure source  16 , for example, a pump, flows (represented by arrows  27 ) from liquid supply  24  through liquid supply channel  11 , liquid dispensing channel  12 , liquid return channel  13 , and back to liquid supply  24  in a continuous manner. When a drop  15  (also referenced as drop  42  in some of the example embodiments described below) of liquid  25  is desired, diverter member  20  is actuated causing a portion of the liquid  25  in liquid dispensing channel  11  to be ejected through outlet opening  26  along drop ejection guide structure  14 . Typically, regulated pressure source  16  is positioned in fluid communication between liquid supply  24  and liquid supply channel  11  and provides a positive pressure that is above atmospheric pressure. 
     Optionally, a regulated vacuum supply  17 , for example, a pump, can be included in the liquid delivery system of liquid dispenser  10  in order to better control liquid flow through liquid dispenser  10 . Typically, regulated vacuum supply  17  is positioned in fluid communication between liquid return channel  13  and liquid supply  24  and provides a vacuum (negative) pressure that is below atmospheric pressure. 
     Liquid dispenser  10  is typically formed from a semiconductor material (for example, silicon) using known semiconductor fabrication techniques (for example, CMOS circuit fabrication techniques, micro-electro mechanical structure (MEMS) fabrication techniques, or combination of both). Alternatively, liquid dispenser  10  can be formed from any materials using any fabrication techniques known in the art. 
     Referring to  FIGS. 2 ,  3 (A), and  3 (B), additional example embodiments of liquid dispenser  10  according to the present invention are shown. Liquid dispenser  10  includes a liquid supply (shown in  FIG. 1 ) that provides liquid  25  under pressure from liquid supply channel  11  through the liquid dispensing channel  12  to the liquid return channel  13 . Liquid dispensing channel  12  including outlet opening  26  that opens directly to atmosphere. Diverter member  20  is selectively actuatable to divert a portion of liquid  25  toward and through outlet opening  26  of liquid dispensing channel  12  when a liquid drop is desired. 
     Liquid return channel  13  includes a porous member  22 , for example, a filter, which helps to minimize pressure changes associated with actuation of diverter member  20  and a portion of liquid  25  being deflected toward outlet opening  26 . This reduces the likelihood of air being drawn into liquid return channel  13  or liquid spilling over outlet opening  26  of liquid dispensing channel  12  during actuation of diverter member  20 . Porous member  22  is typically integrally formed in liquid return channel  13  during the manufacturing process that is used to fabricate liquid dispenser  10 . Alternatively, porous member  22  can be made from a metal or polymeric material and inserted and affixed to one or more of the walls that define liquid return channel  13 . 
     Regardless of whether porous member  22  in integrally formed or fabricated separately, the pores of porous member  22  can have a substantially uniform pore size. Alternatively, the pore size of the pores of porous member  22  can include a gradient so as to be able to more efficiently accommodate liquid flow through the liquid dispenser  10  (for example, larger pore sizes (alternatively, smaller pore sizes) on an upstream portion of the porous member  22  that decrease (alternatively, increase) in size at a downstream portion of porous member  22  when viewed in a direction of liquid travel). The specific configuration of the pores of porous member  22  typically depends on the specific application contemplated. 
     Porous member  22  is positioned in liquid return channel  13  parallel to the flow direction  27  of liquid  25  in liquid dispensing channel  12  such that the openings (pores) of porous member  22  are substantially perpendicular to the liquid flow  27 . As shown in  FIG. 2 , porous member  22  is positioned in liquid return channel  13  at a location that is removed from outlet opening  26  of liquid dispensing channel  12 . As shown in  FIGS. 3(A) and 3(B) , porous member  22  is positioned in liquid return channel  13  at a location that is adjacent to the end  19  of outlet opening  26  of liquid dispensing channel  12 . Porous member  22  extends from a wall  28  of liquid dispensing channel  12  that is opposite outlet opening  26  of liquid dispensing channel  12 . The difference between atmospheric pressure and the negative pressure provided by the regulated vacuum source  17 , described above with reference to  FIG. 1 , is less that the meniscus pressure of porous member  22 . 
     In  FIGS. 2 ,  3 (A), and  3 (B), liquid return channel  13  is shown having a cross-sectional area that is greater than the cross-sectional area of liquid dispensing channel  12 . Additionally, liquid return channel  13  includes a vent  23  that vents liquid return channel  13  to atmosphere. These features, when taken separately or in combination, also help to minimize pressure changes associated with actuation of diverter member  20  and a portion of liquid  25  being deflected toward outlet opening  26  which reduces the likelihood of air being drawn into liquid return channel  13  or liquid spilling over outlet opening  26  of liquid dispensing channel  12  during actuation of diverter member  20 . Drop ejection guide structure  14  which guides the portion of liquid  25  that has been diverted by actuation of diverter member  20  from outlet opening  26  of liquid dispensing channel  12  toward atmosphere is located downstream relative to outlet opening  26  of liquid dispensing channel  12  and upstream relative to the location of vent  23  of liquid return channel  13 . 
     In the example embodiment shown in  FIG. 3(A) , diverter member  20  includes a heater that vaporizes the first liquid portion. This type of heater is commonly referred to as a “bubble jet” heater. As shown in  FIG. 3(B) , diverter member  20  is selectively movable into liquid dispensing channel  12  during actuation. In this example embodiment, diverter member  20  includes a heater, for example, a bi-layer or tri-layer thermal micro-actuator generally described in one or more of the following commonly assigned U.S. Pat. No. 6,464,341 B1; U.S. Pat. No. 6,588,884 B1; U.S. Pat. No. 6,598,960 B1; U.S. Pat. No. 6,721,020 B1; U.S. Pat. No. 6,817,702 B2; U.S. Pat. No. 7,073,890 B2; U.S. Pat. No. 6,869,169 B2; and U.S. Pat. No. 7,188,931 B2. 
     Referring to  FIGS. 4(A) through 4(H)  and  FIGS. 5(A) through 5(C) , additional example embodiments of liquid dispenser  10  made in accordance with the present invention are shown. Liquid dispenser  10  includes a liquid supply channel  11  that includes an exit  21 . Exit  21  of liquid supply channel  11  has a cross sectional area. Liquid dispensing channel  12  includes an outlet opening  26  that includes an end  19  that is adjacent to liquid return channel  13 . Liquid dispensing channel  12  also has a cross sectional area. As shown in  FIGS. 4(A) through 4(H)  and  FIGS. 5(A) through 5(C) , the cross sectional area of a portion of liquid dispensing channel  12  that is located at the end  19  of outlet opening  26  is greater than the cross sectional area of the exit  21  of liquid supply channel  11 . This feature helps to minimize pressure changes associated with actuation of diverter member  20  and the deflecting of a portion of liquid  25  toward outlet opening  26  which reduces the likelihood of air being drawn into liquid return channel  13  or liquid spilling over outlet opening  26  of liquid dispensing channel  12  during actuation of diverter member  20 . 
     As described above with reference to  FIGS. 2 ,  3 (A) and  3 (B), liquid dispenser  10  also includes a liquid return channel  13  and a liquid supply  24  that provides liquid  25  under pressure from liquid supply channel  11  through liquid dispensing channel  12  to the liquid return channel  13 . Diverter member  20  is selectively actuatable to divert a portion  15  of liquid  25  toward outlet opening  26  of liquid dispensing channel  12 . Also, as described above with reference to  FIGS. 3(A) and 3(B) , diverter member  20  is selectively movable into and out of liquid dispensing channel  12  during actuation. Additionally, diverter member  20  can include a heater or can incorporate using heat in its actuation. 
     Referring to  FIGS. 4(A) through 4(H)  and  FIGS. 5(A) through 5(C) , additional example embodiments of liquid dispenser  10  in which a cross sectional area at the end  19  of liquid dispensing channel  12  is greater than a cross sectional area of an exit  21  of liquid supply channel  11  are shown. Specific example embodiments includes those that describe a meniscus height control device, for example, an active device (for example, a bimetallic or tri-metallic actuator like those described above) that appropriately controls liquid dispensing channel wall expansion, contraction, or combinations thereof, or a passive control configuration (for example, a positioning of the walls of liquid supply channel  11 , liquid dispensing channel  12 , or both) that appropriately controls liquid dispensing channel wall expansion (for example, by creating a step up, step down, or another form of a passive liquid dispensing wall expansion). 
     Generally described, liquid dispensing channel  12  includes a first wall  50  and a second wall  52  positioned opposite each other. First wall  50  and second wall  52  extend from the exit  21  of liquid supply channel  11  to the end  19  of outlet opening  26  of liquid dispensing channel  12 . First wall  50  and second wall  52  are spaced farther apart from each other at the end  19  of outlet opening  26  of liquid dispensing channel  12  when compared to the spacing of first wall  50  and second wall  52  at the exit  21  of liquid supply channel  11 . Typically, first wall  50  and second wall  52  are positioned opposite each other. First wall  50  and second wall  52  can be positioned perpendicular to an area defined by outlet opening  26  of liquid dispensing channel  12 . Alternatively, first wall  50  and second wall  52  can be positioned parallel or substantially parallel to the area defined by outlet opening  26  of liquid dispensing channel  12 . Typically, first wall  50  and second wall  52  are symmetrically positioned relative to each other in order to minimize changes in the flow characteristics of the liquid. 
     In some example embodiments described below, liquid supply channel  11  narrows (or “necks down”) in the vicinity of exit  21  of liquid supply channel  11  as viewed in the direction  27  of liquid flow through liquid dispenser  10 . That is, the wall to wall spacing of a first wall  54  and a second wall  56  of liquid supply channel  11  is closer together near the exit  21  than at a location upstream from exit  21 . As such, the cross sectional area of the exit  21  of liquid supply channel  11  is less than the cross section area of liquid supply channel  11  at a location  58  of the liquid supply channel that is upstream of the exit of the liquid supply channel. This is done to maintain or even increase the velocity of the liquid flowing through liquid dispensing channel  12 . Additionally, in a liquid dispenser  10  array, there is limited space between neighboring liquid dispensers  10 . A narrow exit  21  allows a portion the liquid dispensing channel  12  to be wider than exit  21  in order to control the meniscus height of the liquid in the liquid dispensing channel opening  26  so as to reduce or even prevent liquid spills when the diverter member  20  is not activated. 
       FIG. 4(A)  shows an example embodiment in which the spacing between a portion of first wall  50  and a portion of second wall  52  varies in the vicinity of the end  19  of outlet opening  26  of liquid dispensing channel  12  ultimately ending in liquid return channel  13 . To accomplish this, the corresponding portions of first wall  50  and second wall  52  are positioned at a non-parallel angle relative to each other. Alternatively, first wall  50  and second wall  52  portions can include a radius of curvature. In this embodiment, first wall  50  and second wall  52  also include portions that are portioned parallel to each other. These portions are located upstream relative to the non-parallel portions described previously and extend from the exit  21  of liquid supply channel  11  toward the end  19  of outlet opening  26  of liquid dispensing channel  12 . 
       FIG. 4(B)  shows an example embodiments in which the spacing between first wall  50  and second wall  52  varies from the exit  21  of liquid supply channel  11  to end  19  of outlet opening  26  of liquid dispensing channel  12 . To accomplish this, first wall  50  and second wall  52  are positioned at a non-parallel angle relative to each other. Alternatively, first wall  50  and second wall  52  portions can include a radius of curvature. In this embodiment, first wall  50  and second wall  52  end in liquid return channel  13 . 
       FIG. 4(C)  shows an example embodiment in which the spacing between first wall  50  and second wall  52  remains constant along the length of first wall  50  and second wall  52 . In this embodiment, first wall  50  and second wall  52  are positioned parallel relative to each other. In this embodiment, first wall  50  and second wall  52  are recessed from first wall  54  and a second wall  56  of liquid supply channel  11  beginning at the exit  21  of liquid supply channel  11  and continuing toward the end  19  of outlet opening  26  and into liquid return channel  13 . 
     In  FIGS. 4(D) through 4(H)  portions of first wall  50  and second wall  52  are recessed from first wall  54  and a second wall  56  of liquid supply channel  11 . The change occurs more gradually in these embodiments. For example, in  FIGS. 4(D) and 4(H) , first wall  50  and second wall  52  include non-parallel portions  50   a  and  52   a . Non-parallel portions  50   a  and  52   a  begin at the exit  21  of liquid supply channel  11  and end in liquid dispensing channel  12 . Liquid supply channel  11  also includes parallel non-recessed portions  50   b  and  52   b  that begin after the “neck down” region of liquid supply channel and end at the exit  21  of liquid supply channel  11 . Non-parallel portions  50   a  and  52   a  include a radius of curvature in  FIG. 4(H) . The embodiment shown in  FIG. 4(G)  does not include parallel non-recessed portions  50   b  and  52   b . Instead, non-parallel portions  50   a  and  52   a  begin at the exit  21  of liquid supply channel  11  after the “neck down” region of liquid supply channel  11  that ends at exit  21 . 
     In  FIG. 4(E) , first wall  50  and second wall  52  include parallel non-recessed portions  50   b  and  52   b  that begin at the exit  21  of liquid supply channel  11  and extend into liquid dispensing channel  12 . Parallel non-recessed portions  50   b  and  52   b  of first wall  50  and second wall  52  end where non-parallel portions  50   a  and  52   a  begin in liquid dispensing channel  12 . Non-parallel portions  50   a  and  52   a  of first wall  50  and second wall  52  end at the beginning of recessed portions of first wall  50  and second wall  52 . In  FIG. 4(F) , parallel non-recessed portions  50   b  and  52   b  begin prior to the exit  21  of liquid supply channel  11  and extend into liquid dispensing channel  12 . 
     Referring to  FIGS. 5(A) through 5(C) , additional example embodiments of liquid dispenser  10  in which a cross sectional area at the end  19  of liquid dispensing channel  12  is greater than a cross sectional area of an exit  21  of liquid supply channel  11  are shown. In  FIGS. 5(A) and 5(B) , liquid dispensing channel  12  includes a wall  60  positioned opposite outlet opening  26 . Wall  60  extends from the exit  21  of liquid supply channel  11  to the end  19  of outlet opening  26  of liquid dispensing channel  12 . Wall  60  is spaced farther apart from outlet opening  26  at the end  19  of outlet opening  26  of liquid dispensing channel  12  when compared to the exit  21  of liquid supply channel  11 . In  FIG. 5(A) , the change is immediate with wall  60  including a “step down” at the exit  21  of liquid supply channel  11 . In  FIG. 5(B) , the change is more gradual with wall  60  sloping away from outlet opening  26  when viewed in the direction of liquid flow  27  through liquid dispensing channel  12 . 
     In  FIG. 5(C) , wall  60  does not “step down” or slope away. Instead, outer wall  62 , that helps to define end  19  of outlet opening  26 , is offset from outer wall  64  which helps to define the beginning  18  of outlet opening. The offset of outer wall  62  and outer wall  64  creates a cross sectional area at the end  19  of outlet opening  26  of liquid dispensing channel  12  that greater than the cross sectional area of an exit  21  of liquid supply channel  11 . 
     The example embodiments described with reference to  FIGS. 4(A) through 5(C)  included examples of passive control configurations. Other example embodiments can include active devices, for example, those devices described in one or more of the following commonly assigned U.S. Pat. No. 6,464,341 B1; U.S. Pat. No. 6,588,884 B1; U.S. Pat. No. 6,598,960 B1; U.S. Pat. No. 6,721,020 B1; U.S. Pat. No. 6,817,702 B2; U.S. Pat. No. 7,073,890 B2; U.S. Pat. No. 6,869,169 B2; and U.S. Pat. No. 7,188,931 B2. 
     When an active device is implemented liquid dispenser  10  is typically configured as follows. Liquid dispensing channel  12  includes a first wall  50  and a second wall  52  positioned parallel to each other and opposite each other. First wall  50  and second wall  52  extend from the exit  21  of liquid supply channel  11  to the end  19  of outlet opening  26  of liquid dispensing channel  12 . First wall  50  and second wall  52  include a selectively actuatable device that, when actuated, causes the spacing of first wall  50  and second wall  52  to be farther apart from each other at the end  19  of outlet opening  26  of liquid dispensing channel  12  when compared to the exit  21  of liquid supply channel  11 . Alternatively, the active device can be included in a wall  60  of liquid dispensing channel  12  that is positioned opposite outlet opening  26 . Wall  60  extends from the exit  21  of liquid supply channel  11  to the end  19  of outlet opening  26  of liquid dispensing channel  12 . The active device is a selectively actuatable device that, when actuated, causes the spacing of wall  60  to be farther apart from outlet opening  26  at the end  19  of outlet opening  26  of liquid dispensing channel  12  when compared to the exit  19  of liquid supply channel  11 . 
     Referring to  FIGS. 6 through 7(C) , additional example embodiments of liquid dispenser  10  made in accordance with the present invention are shown. These example embodiments describe liquid dispenser  10  configurations which include two dimensional dispenser arrays and monolithic dispenser structures. 
     Generally described, liquid dispenser  10  includes a liquid supply channel  11  that includes an exit  21 . Liquid dispensing channel  12  includes an outlet opening  26  that includes an end  19 . Liquid dispenser  10  also includes a liquid return channel  13  and a liquid supply  24  that provides liquid  25  under pressure from liquid supply channel  11  through liquid dispensing channel  12  to the liquid return channel  13 . Diverter member  20  is selectively actuatable to divert a portion  15  of liquid  25  toward outlet opening  26  of liquid dispensing channel  12 . Also, as described above with reference to  FIGS. 3(A) and 3(B) , diverter member  20  is selectively movable into and out of liquid dispensing channel  12  during actuation. Additionally, diverter member  20  can include a heater or can incorporate using heat in its actuation. 
     As shown in  FIG. 6 , liquid dispenser  10  includes a drop ejection guide structure  14  that is positioned adjacent to and in between the end  19  of outlet opening  26  and vent  23 . Extending from the end  19  of outlet opening  26 , guide structure  14  is shaped to direct the portion of the liquid  25  diverted from liquid dispensing channel  12  through a steep angle (represented by arrows  68  and  70 ) relative to the direction  27  of travel of the liquid  25  provided by liquid supply channel  11 . The term “steep angle” is used herein to describe a guide structure  14  shaped to significantly change the direction of drops  15  formed from the portion of liquid  25  that is diverted by diverter member  20 . As such, as used herein, the term “steep angle” means a change in direction of drop travel as compared to the direction of travel of the liquid that is at least greater than 45 degrees and less than or approximately equal to 90 degrees, and more preferably, that is approximately 90 degrees relative to the direction of travel of the liquid provided by the liquid supply channel. 
     As shown in  FIG. 6 , guide structure  14  is shaped to include a radius of curvature  72  which helps the liquid transition through the steep angle. Alternatively, guide structure can be shaped to include plane positioned relative to outlet opening  26  at the desired steep angle, for example, at an angle of approximately 90 degrees. 
     Referring to  FIGS. 7(A) through 7(D) , liquid dispensers  10  including two dimensional dispenser arrays and monolithic structures are shown. In each figure, liquid dispenser  10  includes a first liquid dispenser array  10   a  and a second liquid dispenser array  10   b . Liquid dispenser arrays  10   a  and  10   b  are the same when compared to each other and have been described above with reference to  FIG. 6 . Guide structure  14 , described above, is one feature of liquid dispenser  10  that advantageously facilitates two dimensional dispenser arrays because the change in drop direction created by guide structure  14  allows individual single array liquid dispensers  10   a  and  10   b  to be arranged adjacent to each other in a side by side configuration. 
     Additionally, liquid dispenser  10   a  and liquid dispenser  10   b  can be integrally formed on a common substrate using the fabrication techniques described above thereby creating a two dimensional monolithic liquid dispenser array structure. When compared to other types of liquid dispensers, monolithic dispenser configurations help to improve the alignment of each outlet opening relative to other outlet openings which improves image quality. Monolithic dispenser configurations also help to reduce spacing in between adjacent outlet openings which increases dots per inch (dpi). 
     In  FIGS. 7(B) and 7(C) , a plurality of first liquid dispensers  10   a  are positioned adjacent to a plurality of second liquid dispensers  10   b  in a first direction  74 . Outlet openings  26  of first liquid dispensers  10   a  and outlet openings  26  of second liquid dispensers  10   b  extend in a second direction  76 . In  FIG. 7(B) , outlet openings  26  of first liquid dispensers  10   a  are aligned with outlet openings  26  of second liquid dispensers  10   b  in the second direction  76 . In  FIG. 7(C) , outlet openings  26  of first liquid dispensers  10   a  are offset relative to outlet openings  26  of second liquid dispensers  10   b  in the second direction  76 . 
     The plurality of first liquid dispensers  10   a  and the plurality of second liquid dispensers  10   b  can be configured differently in first direction  74 . For example, in  FIG. 7(A) , first liquid dispensers  10   a  and second liquid dispensers  10   b  are arranged in a side by side configuration in which liquid  25  flows in the same direction  27  through the liquid dispensing channels  12  of the first liquid dispensers  10   a  and the second liquid dispensers  10   b  (substantially left to right as shown in the figure). 
     In  FIG. 7(D) , first liquid dispensers  10   a  and second liquid dispensers  10   b  are arranged in a side by side configuration with liquid  25  flowing in opposite directions  27  through the liquid dispensing channels  12  of the first liquid dispensers  10   a  and the second liquid dispensers  10   b . Additionally, the outlet openings  26  of the first liquid dispensers  10   a  and the outlet openings  26  of the second liquid dispensers  10   b  are positioned adjacent to each other. By including guide structure  14 , described above, in both liquid dispensers  10   a  and  10   b , the outlet openings of liquid dispensers  10   a  and  10   b  can be more tightly packed together resulting in an increase in dots per inch (dpi). In  FIG. 7(E) , first liquid dispensers  10   a  and second liquid dispensers  10   b  are arranged in a side by side configuration with liquid  25  flowing in opposite directions  27  through the liquid dispensing channels  12  of the first liquid dispensers  10   a  and the second liquid dispensers  10   b . Additionally, the outlet openings  26  of the first liquid dispensers  10   a  and the outlet openings  26  of the second liquid dispensers  10   b  are positioned spaced apart from each other at opposite ends of each liquid dispenser. 
     Referring to  FIGS. 8(A) through 8(D) , additional example embodiments of liquid dispensers made in accordance with the present invention are shown. Liquid dispenser  10  includes a liquid supply channel  11  that is in fluid communication with a liquid return channel  13  through a liquid dispensing channel  12 . Liquid supply channel  11  also includes an exit area  21 . 
     Liquid dispensing channel  12  includes an outlet opening  26 , defined by a beginning  18  and an ending  19 , that opens directly to atmosphere. The beginning  18  of outlet opening  26  also at least partially defines the exit  21  of liquid supply channel  11 . Liquid dispensing channel  12  includes a diverter member  20 . 
     Liquid dispenser  10  also includes a liquid supply  24  that provides liquid  25  to liquid dispenser  10 . During operation, liquid  25 , pressurized by a regulated pressure source  16 , for example, a pump, flows (represented by arrows  27 ) from liquid supply  24  through liquid supply channel  11 , liquid dispensing channel  12 , liquid return channel  13 , and back to liquid supply  24  in a continuous manner. When a drop  15  of liquid  25  is desired, diverter member  20  is actuated causing a portion of the liquid  25  in liquid dispensing channel  11  to be ejected through outlet opening  26  along drop ejection guide structure  14 . Drop ejection guide structure  14  which guides the portion of liquid  25  that has been diverted by actuation of diverter member  20  from outlet opening  26  of liquid dispensing channel  12  toward atmosphere is located downstream relative to outlet opening  26  of liquid dispensing channel  12  and upstream relative to the location of vent  23  of liquid return channel  13 . Typically, regulated pressure source  16  is positioned in fluid communication between liquid supply  24  and liquid supply channel  11  and provides a positive pressure that is above atmospheric pressure. 
     Optionally, a regulated vacuum supply  17 , for example, a pump, can be included in the liquid delivery system of liquid dispenser  10  in order to better control liquid flow through liquid dispenser  10 . Typically, regulated vacuum supply  17  is positioned in fluid communication between liquid return channel  13  and liquid supply  24  and provides a vacuum (negative) pressure that is below atmospheric pressure. 
     Liquid dispenser  10  also includes a liquid cooling channel  32  positioned relative to liquid dispensing channel  12 . Diverter member  20  includes a first side  20   a  that faces liquid dispensing channel  12  and a second side  20   b  that faces liquid cooling channel  31 . Diverter member  20  is selectively actuatable using heat energy to divert a portion  15  of liquid  25  toward outlet opening  26  of liquid dispensing channel  12 . Diverter member  20  either includes a heater or incorporates using heat in its actuation. The liquid flowing through liquid cooling channel  32  helps to cool diverter member  20  after diverter member  20  has been actuated. This helps to increase the frequency at which diverter member  20  can be actuated thereby improving the overall print speed of liquid dispenser  10 . 
     As shown in  FIGS. 8(A) and 8(B) , diverter member  20  is selectively movable into and out of liquid dispensing channel  12  during actuation. Diverter member  20  is an actuator that uses heat energy to change the position of the actuator relative to the liquid dispensing channel. Examples of these types of actuators include, for example, a bi-layer or tri-layer thermal micro-actuator described above with reference to  FIGS. 3(A) and 3(B) . In  FIG. 8(A) , diverter member  20  is cantilevered on one end  82  to a wall  80  of liquid dispenser  10  that helps define liquid dispensing channel  12  and liquid cooling channel  32 . In  FIG. 8(B) , diverter member  20  is anchored on both ends  82  to the wall  80  of liquid dispenser  10  that helps define liquid dispensing channel  12  and liquid cooling channel  32 . 
     In  FIGS. 8(C) and 8(D) , diverter member  20  includes a heater that is commonly referred to as a “bubble jet” heater which, when actuated, vaporizes a portion of the liquid  25  flowing through liquid dispensing channel  12  creating a vapor bubble  33  and causing another portion of the liquid  25  to be diverted toward outlet opening  26 . 
     Referring back to  FIGS. 8(A) through 8(D) , liquid cooling channel  32  is supplied using a second liquid supply channel  31  in liquid communication with liquid cooling channel  32  to provide a second liquid  84  through liquid cooling channel  32 . In  FIGS. 8(A) through 8(C) , liquid supply channel  11  and liquid cooling channel  32  feed into a common liquid return channel  13 . 
     In  FIG. 8(D) , liquid supply channel  11 , referred to as a first liquid supply channel, and second liquid supply channel  31  are physically distinct from each other which allows liquid  25 , referred to as a first liquid, and second liquid  84  to be different types of liquid when compared to each other. For example, second liquid  84  can include properties that increase its ability to remove heat while liquid  25  is an ink. A second liquid return channel  34  is in liquid communication with liquid cooling channel  32 . Liquid return channel  13 , referred to as a first liquid return channel, and second liquid return channel  34  are physically distinct from each other. 
     In the example embodiment shown in  FIG. 8(D) , a second liquid supply  86  is in liquid communication with liquid cooling channel  32 . During operation, second liquid  84 , pressurized above atmospheric pressure by a second regulated pressure source  35 , for example, a pump, flows (represented by arrows  88 ) from second liquid supply  86  through second liquid supply channel  31 , liquid cooling channel  32 , second liquid return channel  34 , and back to second liquid supply  86  in a continuous manner. Optionally, a second regulated vacuum supply  36 , for example, a pump, can be included in the liquid cooling system of liquid dispenser  10  in order to better control cooling liquid flow through liquid dispenser  10 . Typically, second regulated vacuum supply  36  is positioned in fluid communication between second liquid return channel  34  and second liquid supply  86  and provides a vacuum (negative) pressure that is below atmospheric pressure. Again, liquid  25 , referred to as a first liquid, and second liquid  84  can be different types of liquid when compared to each other. Alternatively, liquid  25  and second liquid  84  can be the same type of liquid. 
     First liquid supply  24 , using regulated pressure source  16  and, optionally, regulated vacuum source  17 , regulates the velocity of the first liquid  25  moving through liquid dispensing channel  12  while second liquid supply  86 , using second regulated pressure source  35  and, optionally, second regulated vacuum source  36 , regulates the velocity of second liquid  84  moving through liquid cooling channel  32  so that liquid pressure on both sides of diverter member  20  is balanced. This helps to minimize differences in liquid flow characteristics that may adversely affect liquid diversion and drop formation during operation. Alternatively, liquid dispensing channel  12  and liquid cooling channel  32  can be sized such that liquid pressure on both sides of diverter member  20  is balanced. 
     Referring to  FIGS. 9(A) through 9(F) , additional example embodiments of liquid dispensers made in accordance with the present invention are shown. Liquid dispenser  10  includes a liquid supply channel  11  that is in fluid communication with a liquid return channel  13  through a liquid dispensing channel  12 . Liquid supply channel  11  also includes an exit area  21 . 
     Liquid dispensing channel  12  includes an outlet opening  26 , defined by a beginning  18  and an ending  19 , that opens directly to atmosphere. The beginning  18  of outlet opening  26  also at least partially defines the exit  21  of liquid supply channel  11 . Liquid dispensing channel  12  includes a diverter member  20 . In  FIGS. 9(A) through 9(F) , diverter member  20  includes a heater that is commonly referred to as a “bubble jet” heater, described above. Alternatively, diverter member  20  can include the thermal micro-actuator also described above. 
     Liquid dispenser  10  also includes a liquid supply  24  that provides liquid  25  to liquid dispenser  10 . During operation, liquid  25 , pressurized by a regulated pressure source  16 , for example, a pump, flows (represented by arrows  27 ) from liquid supply  24  through liquid supply channel  11 , liquid dispensing channel  12 , liquid return channel  13 , and back to liquid supply  24  in a continuous manner. When a drop  15  of liquid  25  is desired, diverter member  20  is actuated causing a portion of the liquid  25  in liquid dispensing channel  11  to be ejected through outlet opening  26  along drop ejection guide structure  14 . Drop ejection guide structure  14  which guides the portion of liquid  25  that has been diverted by actuation of diverter member  20  from outlet opening  26  of liquid dispensing channel  12  toward atmosphere is located downstream relative to outlet opening  26  of liquid dispensing channel  12  and upstream relative to the location of vent  23  of liquid return channel  13 . Typically, regulated pressure source  16  is positioned in fluid communication between liquid supply  24  and liquid supply channel  11  and provides a positive pressure that is above atmospheric pressure. 
     Optionally, a regulated vacuum supply  17 , for example, a pump, can be included in the liquid delivery system of liquid dispenser  10  in order to better control liquid flow through liquid dispenser  10 . Typically, regulated vacuum supply  17  is positioned in fluid communication between liquid return channel  13  and liquid supply  24  and provides a vacuum (negative) pressure that is below atmospheric pressure. 
     Liquid dispenser  10  also includes a drop ejection guide structure  14  that reduces viscous drag on the portion of the liquid  25  that has been diverted by diverter member  20 . Drop ejection guide structure  14  includes a liquid structure  44  in  FIGS. 9(A) and 9(B)  and a solid structure  43  in  FIGS. 9(C) through 9(F) . Guide structure  14  is positioned on a portion  90  of a surface  92  of liquid dispenser  10  that is positioned downstream relative to outlet opening  26  of liquid dispensing channel  12 . Guide structure  14  is also positioned at an angle relative to outlet opening  26 . Guide structure  14  provides a path that leads to atmosphere for drops  42  and helps to ensure that drops  42  formed from consecutive portions of liquid  25  that have been diverted by diverter member  20  travel with consistent drop characteristics. These drop characteristics include at least one of a drop volume, a drop velocity, and a drop direction. 
     Surface portion  90  that includes guide structure  14  can be contrasted with another portion  94  of surface  92  that does not include structure that reduces viscous drag on the portion of liquid  25  that has been diverted by diverter member  20 . This other portion  94  can be located anywhere down stream from outlet opening  26 . 
     In  FIGS. 9(A) and 9(B) , guide structure  14  that reduces viscous drag includes a liquid filled ejection guide  44  structure positioned at an angle relative to outlet opening  26  of liquid dispensing channel  12 . Liquid filled guide structure  44  can be a ramp made from a liquid as shown in  FIG. 9(A)  or can be a solid ramp with liquid filled pockets as shown in  FIG. 9(B) . The liquids used in either form of liquid ramp can vary and include, for example, the same liquid as that of liquid  25 . 
     Referring to  FIGS. 9(C) and 9(D) , guide structure  14  can be a grooved drop ejection guide structure  43  positioned at an angle relative to outlet opening  26  of liquid dispensing channel  12 . This structure is also referred to as a grooved ramp in which the grooves are positioned along the direction of drop travel. Referring to  FIGS. 9(E) and 9(F) , guide structure  14  can be include a super hydrophobic drop ejection guide structure  43  positioned at an angle relative to the outlet opening of the liquid dispensing channel. Super hydrophobic drop ejection guide structure  43  includes a plurality of recesses containing air formed in a solid ramp structure. These air filled recesses form an air pocket that drops  42  travel along. In addition, the structures described above can include a hydrophobic coating over one or more of the surface that the drops  42  travel over. Alternatively, the structure  14  that reduces viscous drag can include a hydrophobic coated ejection guide structure, for example, a ramp structure positioned at an angle relative to outlet opening  26  of liquid dispensing channel  12 . 
     Referring to  FIGS. 10(A) through 10(C) , additional example embodiments of liquid dispensers made in accordance with the present invention are shown. Liquid dispenser  10  includes a liquid supply channel  11  that is in fluid communication with a liquid return channel  13  through a liquid dispensing channel  12 . Liquid supply channel  11  also includes an exit area  21 . 
     Liquid dispensing channel  12  includes an outlet opening  26 , defined by a beginning  18  and an ending  19 , that opens directly to atmosphere. The beginning  18  of outlet opening  26  also at least partially defines the exit  21  of liquid supply channel  11 . Liquid dispensing channel  12  includes a diverter member  20 . 
     Liquid dispenser  10  also includes a liquid supply  24  that provides liquid  25  to liquid dispenser  10 . During operation, liquid  25 , pressurized by a regulated pressure source  16 , for example, a pump, flows (represented by arrows  27 ) from liquid supply  24  through liquid supply channel  11 , liquid dispensing channel  12 , liquid return channel  13 , and back to liquid supply  24  in a continuous manner. When a drop  15  of liquid  25  is desired, diverter member  20  is actuated causing a portion of the liquid  25  in liquid dispensing channel  11  to be ejected through outlet opening  26  along drop ejection guide structure  14 . Drop ejection guide structure  14  which guides the portion of liquid  25  that has been diverted by actuation of diverter member  20  from outlet opening  26  of liquid dispensing channel  12  toward atmosphere is located downstream relative to outlet opening  26  of liquid dispensing channel  12  and upstream relative to the location of vent  23  of liquid return channel  13 . Typically, regulated pressure source  16  is positioned in fluid communication between liquid supply  24  and liquid supply channel  11  and provides a positive pressure that is above atmospheric pressure. 
     Optionally, a regulated vacuum supply  17 , for example, a pump, can be included in the liquid delivery system of liquid dispenser  10  in order to better control liquid flow through liquid dispenser  10 . Typically, regulated vacuum supply  17  is positioned in fluid communication between liquid return channel  13  and liquid supply  24  and provides a vacuum (negative) pressure that is below atmospheric pressure. 
     In  FIGS. 10(A) through 10(C) , diverter member  20  is selectively actuatable and imparts heat energy directly to a first portion of liquid  25  to divert a second portion of liquid  25  toward outlet opening  26  of liquid dispensing channel  12 . First liquid portion and second liquid portion are different portions of liquid  25 . Diverter member  20  is non-moving and located in a fixed position. Diverter member  20  includes a stationary heater. As liquid dispenser  10  does not include a conventional nozzle, liquid dispenser  10  is less likely to experience clogging in the area of the outlet opening. 
     In the example embodiment shown in  FIG. 10(A) , diverter member  20  includes a heater that vaporizes the first liquid portion. This type of heater is commonly referred to as a “bubble jet” heater, described above. In the example embodiments shown in  FIGS. 10(B) and 10(C) , diverter member  20  is a heater that heats a portion of liquid  25  to change a liquid flow characteristic. For example, diverter member  20  can be a heater that reduces viscosity of the first portion of the liquid  25  to cause a velocity change in the first portion of the liquid and in the second portion of the liquid. This change in velocity causes a directional change in the second portion of liquid  25 , either toward outlet opening  26  or away from outlet opening  26  depending on the specific configuration of liquid dispenser  10 . Heaters that change viscosity are known, having been described in one or more of the following commonly assigned U.S. Pat. No. 6,079,821; U.S. Pat. No. 6,213,595 B1; U.S. Pat. No. 6,254,225 B1; U.S. Pat. No. 6,217,156 B1; U.S. Pat. No. 6,217,163 B1; and U.S. Pat. No. 6,505,921 B2. 
     Typically, diverter member  20  is positioned in liquid dispensing channel  12  opposite outlet opening  26 . However, diverter member  20  can be positioned in liquid supply channel  11 . For example, diverter member  20  can be located on a wall  100  of liquid supply channel  11  that is an extension of a wall  102  of liquid dispensing channel  12  that is opposite outlet opening  26  of liquid dispensing channel  12 . When positioned in liquid supply channel  11 , diverter member  20  is located upstream relative to outlet opening  26 . When located upstream relative to outlet opening  26 , diverter member  20  can be located on a wall  104  of liquid supply channel that is adjacent to outlet opening  26  of liquid dispensing channel  12 . Diverter member  20  can also be positioned in liquid return channel  13 . For example, diverter member  20  can be located on a wall  106  of liquid return channel  13  that is an extension of a wall  102  of liquid dispensing channel  12  that is opposite outlet opening  26  of liquid dispensing channel  12 . When positioned in liquid return  13 , diverter member  20  is located downstream relative to outlet opening  26 . When located downstream relative to outlet opening  26 , diverter member  20  can be located on a wall  108  of liquid return channel  13  that is adjacent to outlet opening  26  of liquid dispensing channel  12 . 
     Combinations of diverter member  20  locations are also permitted. For example, in  FIG. 10(A) , diverter members  20  are positioned in liquid supply channel  11 , liquid dispensing channel  12 , and liquid return channel  13  on walls that are opposite outlet opening  26  and on walls that are adjacent to outlet opening  26 . In  FIGS. 10(B) and 10(C) , diverter members  20  are positioned in liquid supply channel  11  and liquid dispensing channel  12  on walls that are opposite outlet opening  26  and on walls that are adjacent to outlet opening  26 . 
     In  FIGS. 10(B) and 10(C) , liquid dispensing channel  12  includes a Coanda surface  110  that the liquid  25  travels along. The Coanda surface  110  is positioned opposite outlet opening  26 . Liquid  25  traveling along this surface tends to stay in contact with surface  110  unless diverter member  20  is actuated. This allows liquid supply channel  11  and liquid return channel  13  to be offset relative to each other making the ejection of liquid drops  42  less complicated (when compared to conventional dispensers). In  FIG. 10(B) , Coanda surface  110  is planer and angled away from the outlet of liquid supply channel  11 . In  FIG. 10(C) , Coanda surface  110  includes a radius of curvature that angles away from the outlet of liquid supply channel  11 . 
     When the velocity of the liquid in the liquid dispensing channel  12  is below a threshold velocity (the specific velocity varies depending on the application that the liquid dispenser  10  is being used for), the liquid in the liquid dispensing channel  12  stays in contact with surface  110  in the liquid dispensing channel  12  due to Coanda effect. When the velocity of the liquid in the liquid dispensing channel  12  is above the threshold velocity, the momentum of the liquid overcomes the Coanda effect and the liquid in the liquid dispensing channel  12  detaches from surface  110  in the liquid dispensing channel  12  and the liquid is diverted out of the opening  26  of the liquid dispensing channel  12  to form liquid drops  42 . 
     The Coanda effect on the liquid in the liquid dispensing channel  12  can be enhanced or reduced through asymmetric heating of the liquid in the liquid supply channel  11  through activation of different heaters located on the walls of the liquid supply channel  11 . Asymmetric heating causes a portion of the liquid to be heated, the portion of heated fluid has lower viscosity and higher velocity than the adjacent unheated fluid portion. When the asymmetric heating enhances the Coanda effect, the liquid in the liquid dispensing channel  12  stays in contact with surface  110  in the liquid dispensing channel  12  and flow towards to the liquid return channel  13 . When the asymmetric heating reduces the Coanda effect, the liquid in the liquid dispensing channel  12  detaches from surface  110  in the liquid dispensing channel  12  and the liquid is diverted out of the opening  26  of the liquid dispensing channel  12  to form liquid drops  42 . 
     The example embodiments described above can be implemented individually (by themselves) or in combination with each other to obtain the desired liquid dispenser performance. Accordingly, a liquid dispenser of the present invention can include more than one feature described above. As such, the diverter member features described with reference to  FIGS. 10(A) through 10(C) , the guide structure features described with reference to  FIGS. 9(A) through 9(F) , the spill reduction features described with reference to  FIGS. 2 through 5(C) , the drop directional control features and monolithic two dimensional array features described with reference to  FIGS. 6(A) through 7(E) , and the diverter member cooling features described with reference to  FIGS. 8(A) through 8(D)  can be used in various combinations with each other. 
     The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the scope of the invention. 
     PARTS LIST 
     
         
           10  liquid dispenser 
           10   a  first liquid dispenser array 
           10   b  second liquid dispenser array 
           11  liquid supply channel 
           12  liquid dispensing channel 
           13  liquid return channel 
           14  drop ejection guide structure 
           15  drop 
           16  regulated pressure source 
           17  regulated vacuum supply 
           18  beginning 
           19  ending 
           20  diverter member 
           20   a  first side 
           20   b  second side 
           21  exit 
           22  porous member 
           23  vent 
           24  liquid supply 
           25  liquid 
           26  outlet opening 
           27  arrows 
           28  wall 
           31  second liquid supply channel 
           32  liquid cooling channel 
           33  vapor bubble 
           34  second liquid return channel 
           35  second regulated pressure source 
           36  second regulated vacuum supply 
           42  drops 
           43  solid structure 
           44  liquid structure 
           50  first wall 
           50   a  non-parallel portions 
           50   b  parallel non-recessed portions 
           52  second wall 
           52   a  non-parallel portions 
           52   b  parallel non-recessed portions 
           54  first wall 
           56  second wall 
           58  location 
           60  wall 
           62  outer wall 
           64  outer wall 
           68  arrows 
           70  arrows 
           72  curvature 
           74  first direction 
           76  second direction 
           80  wall 
           82  end 
           84  second liquid 
           86  second liquid supply 
           88  arrows 
           90  surface portion 
           92  surface 
           94  another portion 
           100  wall 
           102  wall 
           104  wall 
           106  wall 
           108  wall 
           110  Coanda surface