Patent Publication Number: US-8529021-B2

Title: Continuous liquid ejection using compliant membrane transducer

Description:
Reference is made to commonly-assigned, U.S. patent applications Ser. No. 13/089,541, titled “MEMS COMPOSITE TRANSDUCER INCLUDING COMPLIANT MEMBRANE”, Ser. No. 13/089,523, now U.S. Pat. No. 8,409.900, entitled “FABRICATING MEMS COMPOSITE TRANSDUCER INCLUDING COMPLIANT MEMBRANE ”, Ser. No. 13/089,521, now U.S. Pat. No. 8,398,210, entitled “CONTINUOUS EJECTION SYSTEM INCLUDING COMPLIANT MEMBRANE TRANSDUCER”, all filed concurrently herewith. 
     FIELD OF THE INVENTION 
     This invention relates generally to the field of digitally controlled liquid ejection systems, and in particular to continuous liquid ejection systems in which a liquid stream breaks into drops at least some of which are deflected. 
     BACKGROUND OF THE INVENTION 
     Ink jet printing has become recognized as a prominent contender in the digitally controlled, electronic printing arena because, e.g., of its non-impact, low-noise characteristics, its use of plain paper and its avoidance of toner transfer and fixing. Ink jet printing mechanisms can be categorized by technology as either drop on demand ink jet (DOD) or continuous ink jet (CIJ). 
     The first technology, “drop-on-demand” (DOD) ink jet printing, provides ink drops that impact upon a recording surface using a pressurization actuator, for example, a thermal, piezoelectric, or electrostatic actuator. One commonly practiced drop-on-demand technology uses thermal actuation to eject ink drops from a nozzle. A heater, located at or near the nozzle, heats the ink sufficiently to boil, forming a vapor bubble that creates enough internal pressure to eject an ink drop. This form of inkjet is commonly termed “thermal ink jet (TIJ).” 
     The second technology commonly referred to as “continuous” ink jet (CIJ) printing, uses a pressurized ink source to produce a continuous liquid jet stream of ink by forcing ink, under pressure, through a nozzle. The stream of ink is perturbed using a drop forming mechanism such that the liquid jet breaks up into drops of ink in a predictable manner. One continuous printing technology uses thermal stimulation of the liquid jet with a heater to form drops that eventually become print drops and non-print drops. Printing occurs by selectively deflecting one of the print drops and the non-print drops and catching the non-print drops. Various approaches for selectively deflecting drops have been developed including electrostatic deflection, air deflection, and thermal deflection. 
     Micro-Electro-Mechanical Systems (or MEMS) devices are becoming increasingly prevalent as low-cost, compact devices having a wide range of applications. Uses include pressure sensors, accelerometers, gyroscopes, microphones, digital mirror displays, microfluidic devices, biosensors, chemical sensors, and others. 
     MEMS transducers include both actuators and sensors. In other words they typically convert an electrical signal into a motion, or they convert a motion into an electrical signal. They are typically made using standard thin film and semiconductor processing methods. As new designs, methods and materials are developed, the range of usages and capabilities of MEMS devices can be extended. 
     MEMS transducers are typically characterized as being anchored to a substrate and extending over a cavity in the substrate. Three general types of such transducers include a) a cantilevered beam having a first end anchored and a second end cantilevered over the cavity; b) a doubly anchored beam having both ends anchored to the substrate on opposite sides of the cavity; and c) a clamped sheet that is anchored around the periphery of the cavity. Type c) is more commonly called a clamped membrane, but the word membrane will be used in a different sense herein, so the term clamped sheet is used to avoid confusion. 
     Sensors and actuators can be used to sense or provide a displacement or a vibration. For example, the amount of deflection δ of the end of a cantilever in response to a stress a is given by Stoney&#39;s formula
 
δ=3σ(1−ν) L   2   /Et   2   (1),
 
where ν is Poisson&#39;s ratio, E is Young&#39;s modulus, L is the beam length, and t is the thickness of the cantilevered beam. In order to increase the amount of deflection for a cantilevered beam, one can use a longer beam length, a smaller thickness, a higher stress, a lower Poisson&#39;s ratio, or a lower Young&#39;s modulus. The resonant frequency of vibration of an undamped cantilevered beam is given by
 
 f=ω   0 /2π=( k/m ) 1/2 /2π  (2),
 
where k is the spring constant and m is the mass. For a cantilevered beam of constant width w, the spring constant k is given by
 
 k=Ewt   3 /4 L   3   (3).
 
It can be shown that the dynamic mass m of an oscillating cantilevered beam is approximately one quarter of the actual mass of ρwtL (ρ being the density of the beam material), so that within a few percent, the resonant frequency of vibration of an undamped cantilevered beam is approximately
 
 f˜ ( t/ 2π L   2 ) ( E/ρ ) 1/2   (4).
 
For a lower resonant frequency one can use a smaller Young&#39;s modulus, a smaller thickness, a longer length, or a larger density. A doubly anchored beam typically has a lower amount of deflection and a higher resonant frequency than a cantilevered beam having comparable geometry and materials. A clamped sheet typically has an even lower amount of deflection and an even higher resonant frequency.
 
     Based on material properties and geometries commonly used for MEMS transducers the amount of deflection can be limited, as can the frequency range, so that some types of desired usages are either not available or do not operate with a preferred degree of energy efficiency, spatial compactness, or reliability. For example, using typical thin film transducer materials for an undamped cantilevered beam of constant width, Equation 4 indicates that a resonant frequency of several megahertz is obtained for a beam having a thickness of 1 to 2 microns and a length of around 20 microns. However, to obtain a resonant frequency of 1 kHz for a beam thickness of about 1 micron, a length of around 750 microns would be required. Not only is this undesirably large, a beam of this length and thickness can be somewhat fragile. In addition, typical MEMS transducers operate independently. For some applications independent operation of MEMS transducers is not able to provide the range of performance desired. Further, typical MEMS transducer designs do not provide a sealed cavity which can be beneficial for some fluidic applications. 
     Thermal stimulation of liquids, for example, inks, ejected from DOD printing mechanisms or formed by CIJ printing mechanisms is not consistent when one liquid is compared to another liquid. Some liquid properties, for example, stability and surface tension, react differently relative to temperature. As such, liquids are affected differently by thermal stimulation often resulting in inconsistent drop formation which reduces the numbers and types of liquid formulations used with DOD printing mechanisms or CIJ printing mechanisms. 
     Accordingly, there is an ongoing need to provide liquid ejection mechanisms and ejection methods that improve the reliability or consistency of drop formation on a liquid by liquid basis while maintaining individual nozzle control of the mechanism in order to increase the numbers and types of liquid formulations used with these mechanisms. 
     SUMMARY OF THE INVENTION 
     According to an aspect of the invention, a method of continuously ejecting liquid includes providing a liquid ejection system that includes a substrate and an orifice plate affixed to the substrate. Portions of the substrate define a liquid chamber. The orifice plate includes a MEMS transducing member. A first portion of the MEMS transducing member is anchored to the substrate. A second portion of the MEMS transducing member extends over at least a portion of the liquid chamber. The second portion of the MEMS transducing member is free to move relative to the liquid chamber. A compliant membrane is positioned in contact with the MEMS transducing member. A first portion of the compliant membrane covers the MEMS transducing member and a second portion of the compliant membrane is anchored to the substrate. The compliant membrane includes an orifice. Liquid is provided under a pressure sufficient to eject a continuous jet of the liquid through the orifice located in the compliant membrane of the orifice plate by a liquid supply. A drop of liquid is caused to break off from the liquid jet by selectively actuating the MEMS transducing member which causes a portion of the compliant membrane to be displaced relative to the liquid chamber. 
    
    
     
       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. 1A  is a top view and  FIG. 1B  is a cross-sectional view of an embodiment of a MEMS composite transducer including a cantilevered beam and a compliant membrane over a cavity; 
         FIG. 2  is a cross-sectional view similar to  FIG. 1B , where the cantilevered beam is deflected; 
         FIG. 3  is a top view of an embodiment similar to  FIG. 1A , but with a plurality of cantilevered beams over the cavity; 
         FIG. 4  is a top view of an embodiment similar to  FIG. 3 , but where the widths of the cantilevered beams are larger at their anchored ends than at their free ends; 
         FIG. 5  is a top view of an embodiment similar to  FIG. 4 , but in addition including a second group of cantilevered beams having a different shape; 
         FIG. 6  is a top view of another embodiment including two different groups of cantilevered beams of different shapes; 
         FIG. 7  is a top view of an embodiment where the MEMS composite transducer includes a doubly anchored beam and a compliant membrane; 
         FIG. 8A  is a cross-sectional view of the MEMS composite transducer of  FIG. 7  in its undeflected state; 
         FIG. 8B  is a cross-sectional view of the MEMS composite transducer of  FIG. 7  in its deflected state; 
         FIG. 9  is a top view of an embodiment where the MEMS composite transducer includes two intersecting doubly anchored beams and a compliant membrane; 
         FIG. 10  is a top view of an embodiment where the MEMS composite transducer includes a clamped sheet and a compliant membrane; 
         FIG. 11A  is a cross-sectional view of the MEMS composite transducer of  FIG. 10  in its undeflected state; 
         FIG. 11B  is a cross-sectional view of the MEMS composite transducer of  FIG. 10  in its deflected state; 
         FIG. 12A  is a cross-sectional view of an embodiment similar to that of  FIG. 1A , but also including an additional through hole in the substrate; 
         FIG. 12B  is a cross-sectional view of a fluid ejector that incorporates the structure shown in  FIG. 12A ; 
         FIG. 13  is a top view of an embodiment similar to that of  FIG. 10 , but where the compliant membrane also includes a hole; 
         FIG. 14  is a cross-sectional view of the embodiment shown in  FIG. 13 ; 
         FIG. 15  is a cross-sectional view showing additional structural detail of an embodiment of a MEMS composite transducer including a cantilevered beam; 
         FIG. 16A  is a cross-sectional view of an embodiment similar to that of  FIG. 6 , but also including an attached mass that extends into the cavity; 
         FIG. 16B  is a cross-sectional view of an embodiment similar to that of  FIG. 16A , but where the attached mass is on the opposite side of the compliant membrane; 
         FIGS. 17A to 17E  illustrate an overview of a method of fabrication; 
         FIGS. 18A and 18B  provide addition details of layers that can be part of the MEMS composite transducer; 
         FIG. 19A  is a schematic cross-sectional view of an example embodiment of a jetting module of a continuous liquid ejection system made in accordance with the present invention; 
         FIG. 19B  is a schematic cross-sectional view of the example embodiment shown in  FIG. 19A  with the drop generator in an actuated position; 
         FIG. 20  is a schematic top view of another example embodiment of a jetting module of a continuous liquid ejection system made in accordance with the present invention; 
         FIG. 21A  is a schematic cross-sectional view of the example embodiment shown in  FIG. 20 ; 
         FIG. 21B  is a schematic cross-sectional view of the example embodiment shown in  FIG. 20  showing in-plane actuation of a drop generator for drop formation; 
         FIG. 21C  is a schematic cross-sectional view of the example embodiment shown in  FIG. 20  showing out of plane actuation of a drop generator for drop formation; 
         FIG. 22  is a schematic cross-sectional view of an example embodiment of a jetting module showing out of plane actuation of a drop generator for drop formation and drop steering; 
         FIG. 23A  is a schematic cross-sectional view of another example embodiment of a jetting module showing out of plane actuation of a drop generator for drop formation and drop steering; 
         FIG. 23B  is a schematic cross-sectional view of another example embodiment of a jetting module showing out of plane actuation of a drop generator for drop formation and drop steering; 
         FIG. 24A  is a schematic cross-sectional view of another example embodiment of a jetting module showing out of plane actuation of a drop generator for drop formation and increased drop steering control; 
         FIG. 24B  is a schematic cross-sectional view of another example embodiment of a jetting module showing out of plane actuation of a drop generator for drop formation and increased drop steering control; 
         FIGS. 25-27B  show an example embodiment of a continuous liquid ejection system made in accordance with the present invention; 
         FIGS. 28-30  show another example embodiment of a continuous liquid ejection system made in accordance with the present invention; and 
         FIG. 31  shows a block diagram describing an example embodiment of a method of continuously ejecting liquid using the continuous liquid ejection system described herein. 
     
    
    
     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 liquid ejection components typically used in inkjet printing systems. 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 ejection system or the liquid ejection system components described below. 
     Embodiments of the present invention include a variety of types of MEMS transducers including a MEMS transducing member and a compliant membrane positioned in contact with the MEMS transducing member. It is to be noted that in some definitions of MEMS structures, MEMS components are specified to be between 1 micron and 100 microns in size. Although such dimensions characterize a number of embodiments, it is contemplated that some embodiments will include dimensions outside that range. 
       FIG. 1A  shows a top view and  FIG. 1B  shows a cross-sectional view (along A-A′) of a first embodiment of a MEMS composite transducer  100 , where the MEMS transducing member is a cantilevered beam  120  that is anchored at a first end  121  to a first surface  111  of a substrate  110 . Portions  113  of the substrate  110  define an outer boundary  114  of a cavity  115 . In the example of FIGS. IA and  1 B, the cavity  115  is substantially cylindrical and is a through hole that extends from a first surface  111  of substrate  110  (to which a portion of the MEMS transducing member is anchored) to a second surface  112  that is opposite first surface  111 . Other shapes of cavity  115  are contemplated for other embodiments in which the cavity  115  does not extend all the way to the second surface  112 . Still other embodiments are contemplated where the cavity shape is not cylindrical with circular symmetry. A portion of cantilevered beam  120  extends over a portion of cavity  115  and terminates at second end  122 . The length L of the cantilevered beam extends from the anchored end  121  to the free end  122 . Cantilevered beam  120  has a width w 1  at first end  121  and a width w 2  at second end  122 . In the example of  FIGS. 1A and 1B , w 1 =w 2 , but in other embodiments described below that is not the case. 
     MEMS transducers having an anchored beam cantilevering over a cavity are well known. A feature that distinguishes the MEMS composite transducer  100  from conventional devices is a compliant membrane  130  that is positioned in contact with the cantilevered beam  120  (one example of a MEMS transducing member). Compliant membrane includes a first portion  131  that covers the MEMS transducing member, a second portion  132  that is anchored to first surface  111  of substrate  110 , and a third portion  133  that overhangs cavity  115  while not contacting the MEMS transducing member. In a fourth region  134 , compliant membrane  130  is removed such that it does not cover a portion of the MEMS transducing member near the first end  121  of cantilevered beam  120 , so that electrical contact can be made as is discussed in further detail below. In the example shown in  FIG. 1B , second portion  132  of compliant membrane  130  that is anchored to substrate  110  is anchored around the outer boundary  114  of cavity  115 . In other embodiments, it is contemplated that the second portion  132  would not extend entirely around outer boundary  114 . 
     The portion (including end  122 ) of the cantilevered beam  120  that extends over at least a portion of cavity  115  is free to move relative to cavity  115 . A common type of motion for a cantilevered beam is shown in  FIG. 2 , which is similar to the view of  FIG. 1B  at higher magnification, but with the cantilevered portion of cantilevered beam  120  deflected upward away by a deflection δ=Δz from the original undeflected position shown in  FIG. 1B  (the z direction being perpendicular to the x-y plane of the surface  111  of substrate  110 ). Such a bending motion is provided for example in an actuating mode by a MEMS transducing material (such as a piezoelectric material, or a shape memory alloy, or a thermal bimorph material) that expands or contracts relative to a reference material layer to which it is affixed when an electrical signal is applied, as is discussed in further detail below. When the upward deflection out of the cavity is released (by stopping the electrical signal), the MEMS transducer typically moves from being out of the cavity to into the cavity before it relaxes to its undeflected position. Some types of MEMS transducers have the capability of being driven both into and out of the cavity, and are also freely movable into and out of the cavity. 
     The compliant membrane  130  is deflected by the MEMS transducer member such as cantilevered beam  120 , thereby providing a greater volumetric displacement than is provided by deflecting only cantilevered beam (of conventional devices) that is not in contact with a compliant membrane  130 . Desirable properties of compliant membrane  130  are that it have a Young&#39;s modulus that is much less than the Young&#39;s modulus of typical MEMS transducing materials, a relatively large elongation before breakage, excellent chemical resistance (for compatibility with MEMS manufacturing processes), high electrical resistivity, and good adhesion to the transducer and substrate materials. Some polymers, including some epoxies, are well adapted to be used as a compliant membrane  130 . Examples include TMMR liquid resist or TMMF dry film, both being products of Tokyo Ohka Kogyo Co. The Young&#39;s modulus of cured TMMR or TMMF is about 2 GPa, as compared to approximately 70 GPa for a silicon oxide, around 100 GPa for a PZT piezoelectric, around 160 GPa for a platinum metal electrode, and around 300 GPa for silicon nitride. Thus the Young&#39;s modulus of the typical MEMS transducing member is at least a factor of 10 greater, and more typically more than a factor of 30 greater than that of the compliant membrane  130 . A benefit of a low Young&#39;s modulus of the compliant membrane is that the design can allow for it to have negligible effect on the amount of deflection for the portion  131  where it covers the MEMS transducing member, but is readily deflected in the portion  133  of compliant membrane  130  that is nearby the MEMS transducing member but not directly contacted by the MEMS transducing member. Furthermore, because the Young&#39;s modulus of the compliant membrane  130  is much less than that of the typical MEMS transducing member, it has little effect on the resonant frequency of the MEMS composite transducer  100  if the MEMS transducing member (e.g. cantilevered beam  120 ) and the compliant membrane  130  have comparable size. However, if the MEMS transducing member is much smaller than the compliant membrane  130 , the resonant frequency of the MEMS composite transducer can be significantly lowered. In addition, the elongation before breaking of cured TMMR or TMMF is around 5%, so that it is capable of large deflection without damage. 
     There are many embodiments within the family of MEMS composite transducers  100  having one or more cantilevered beams  120  as the MEMS transducing member covered by the compliant membrane  130 . The different embodiments within this family have different amounts of displacement or different resonant frequencies or different amounts of coupling between multiple cantilevered beams  120  extending over a portion of cavity  115 , and thereby are well suited to a variety of applications. 
       FIG. 3  shows a top view of a MEMS composite transducer  100  having four cantilevered beams  120  as the MEMS transducing members, each cantilevered beam  120  including a first end that is anchored to substrate  110 , and a second end  122  that is cantilevered over cavity  115 . For simplicity, some details such as the portions  134  where the compliant membrane is removed are not shown in  FIG. 3 . In this example, the widths w 1  (see  FIG. 1A ) of the first ends  121  of the cantilevered beams  120  are all substantially equal to each other, and the widths w 2  (see  FIG. 1A ) of the second ends  122  of the cantilevered beams  120  are all substantially equal to each other. In addition, w 1 =w 2  in the example of  FIG. 3 . Compliant membrane  130  includes first portions  131  that cover the cantilevered beams  120  (as seen more clearly in  FIG. 1B ), a second portion  132  that is anchored to substrate  110 , and a third portion  133  that overhangs cavity  115  while not contacting the cantilevered beams  120 . The compliant member  130  in this example provides some coupling between the different cantilevered beams  120 . In addition, for embodiments where the cantilevered beams are actuators, the effect of actuating all four cantilevered beams  120  results in an increased volumetric displacement and a more symmetric displacement of the compliant membrane  130  than the single cantilevered beam  120  shown in  FIGS. 1A ,  1 B and  2 . 
       FIG. 4  shows an embodiment similar to  FIG. 3 , but for each of the four cantilevered beams  120 , the width w 1  at the anchored end  121  is greater than the width w 2  at the cantilevered end  122 . For embodiments where the cantilevered beams  120  are actuators, the effect of actuating the cantilevered beams of  FIG. 4  provides a greater volumetric displacement of compliant membrane  130 , because a greater portion of the compliant membrane is directly contacted and supported by cantilevered beams  120 . As a result the third portion  133  of compliant membrane  130  that overhangs cavity  115  while not contacting the cantilevered beams  120  is smaller in  FIG. 4  than in  FIG. 3 . This reduces the amount of sag in third portion  133  of compliant membrane  130  between cantilevered beams  120  as the cantilevered beams  120  are deflected. 
       FIG. 5  shows an embodiment similar to  FIG. 4 , where in addition to the group of cantilevered beams  120   a  (one example of a MEMS transducing member) having larger first widths w 1  than second widths w 2 , there is a second group of cantilevered beams  120   b  (alternating arranged between elements of the first group) having first widths w 1 ′ that are equal to second widths w 2 ′. Furthermore, the second group of cantilevered beams  120   b  are sized smaller than the first group of cantilevered beams  120   a , such that the first widths w 1 ′ are smaller than first widths w 1 , the second widths w 2 ′ are smaller than second widths w 2 , and the distances (lengths) between the anchored first end  121  and the free second end  122  are also smaller for the group of cantilevered beams  120   b . Such an arrangement is beneficial when the first group of cantilevered beams  120   a  are used for actuators and the second group of cantilevered beams  120   b  are used as sensors. 
       FIG. 6  shows an embodiment similar to  FIG. 5  in which there are two groups of cantilevered beams  120   c  and  120   d , with the elements of the two groups being alternating arranged. In the embodiment of  FIG. 6  however, the lengths L and L′ of the cantilevered beams  120   c  and  120   d  respectively (the distances from anchored first ends  121  to free second ends  122 ) are less than 20% of the dimension D across cavity  115 . In this particular example, where the outer boundary  114  of cavity  115  is circular, D is the diameter of the cavity  115 . In addition, in the embodiment of  FIG. 6 , the lengths L and L′ are different from each other, the first widths w 1  and w 1 ′ are different from each other, and the second widths w 2  and w 2 ′ are different from each other for the cantilevered beams  120   c  and  120   d . Such an embodiment is beneficial when the groups of both geometries of cantilevered beams  120   c  and  120   d  are used to convert a motion of compliant membrane  130  to an electrical signal, and it is desired to pick up different amounts of deflection or at different frequencies (see equations 1, 2 and 3 in the background). 
     In the embodiments shown in FIGS.  1 A and  3 - 6 , the cantilevered beams  120  (one example of a MEMS transducing member) are disposed with substantially radial symmetry around a circular cavity  115 . This can be a preferred type of configuration in many embodiments, but other embodiments are contemplated having nonradial symmetry or noncircular cavities. For embodiments including a plurality of MEMS transducing members as shown in  FIGS. 3-6 , the compliant membrane  130  across cavity  115  provides a degree of coupling between the MEMS transducing members. For example, the actuators discussed above relative to  FIGS. 4 and 5  can cooperate to provide a larger combined force and a larger volumetric displacement of compliant membrane  130  when compared to a single actuator. The sensing elements (converting motion to an electrical signal) discussed above relative to  FIGS. 5 and 6  can detect motion of different regions of the compliant membrane  130 . 
       FIG. 7  shows an embodiment of a MEMS composite transducer in a top view similar to  FIG. 1A , but where the MEMS transducing member is a doubly anchored beam  140  extending across cavity  115  and having a first end  141  and a second end  142  that are each anchored to substrate  110 . As in the embodiment of  FIGS. 1A and 1B , compliant membrane  130  includes a first portion  131  that covers the MEMS transducing member, a second portion  132  that is anchored to first surface  111  of substrate  110 , and a third portion  133  that overhangs cavity  115  while not contacting the MEMS transducing member. In the example of  FIG. 7 , a portion  134  of compliant membrane  130  is removed over both first end  141  and second end  142  in order to make electrical contact in order to pass a current from the first end  141  to the second end  142 . 
       FIG. 8A  shows a cross-sectional view of a doubly anchored beam  140  MEMS composite transducer in its undeflected state, similar to the cross-sectional view of the cantilevered beam  120  shown in  FIG. 1B . In this example, a portion  134  of compliant membrane  130  is removed only at anchored second end  142  in order to make electrical contact on a top side of the MEMS transducing member to apply (or sense) a voltage across the MEMS transducing member as is discussed in further detail below. Similar to  FIGS. 1A and 1B , the cavity  115  is substantially cylindrical and extends from a first surface  111  of substrate  110  to a second surface  112  that is opposite first surface  111 . 
       FIG. 8B  shows a cross-sectional view of the doubly anchored beam  140  in its deflected state, similar to the cross-sectional view of the cantilevered beam  120  shown in  FIG. 2 . The portion of doubly anchored beam  140  extending across cavity  115  is deflected up and away from the undeflected position of  FIG. 8A , so that it raises up the portion  131  of compliant membrane  130 . The maximum deflection at or near the middle of doubly anchored beam  140  is shown as δ=Δz. 
       FIG. 9  shows a top view of an embodiment similar to that of  FIG. 7 , but with a plurality (for example, two) of doubly anchored beams  140  anchored to the substrate  110  at their first end  141  and second end  142 . In this embodiment both doubly anchored beams  140  are disposed substantially radially across circular cavity  115 , and therefore the two doubly anchored beams  140  intersect each other over the cavity at an intersection region  143 . Other embodiments are contemplated in which a plurality of doubly anchored beams do not intersect each other or the cavity is not circular. For example, two doubly anchored beams can be parallel to each other and extend across a rectangular cavity. 
       FIG. 10  shows an embodiment of a MEMS composite transducer in a top view similar to  FIG. 1A , but where the MEMS transducing member is a clamped sheet  150  extending across a portion of cavity  115  and anchored to the substrate  110  around the outer boundary  114  of cavity  115 . Clamped sheet  150  has a circular outer boundary  151  and a circular inner boundary  152 , so that it has an annular shape. As in the embodiment of  FIGS. 1 and 1B , compliant membrane  130  includes a first portion  131  that covers the MEMS transducing member, a second portion  132  that is anchored to first surface  111  of substrate  110 , and a third portion  133  that overhangs cavity  115  while not contacting the MEMS transducing member. In a fourth region  134 , compliant membrane  130  is removed such that it does not cover a portion of the MEMS transducing member, so that electrical contact can be made as is discussed in further detail below. 
       FIG. 11A  shows a cross-sectional view of a clamped sheet  150  MEMS composite transducer in its undeflected state, similar to the cross-sectional view of the cantilevered beam  120  shown in  FIG. 1B . Similar to  FIGS. 1A and 1  B, the cavity  115  is substantially cylindrical and extends from a first surface  111  of substrate  110  to a second surface  112  that is opposite first surface  111 . 
       FIG. 11B  shows a cross-sectional view of the clamped sheet  150  in its deflected state, similar to the cross-sectional view of the cantilevered beam  120  shown in  FIG. 2 . The portion of clamped sheet  150  extending across cavity  115  is deflected up and away from the undeflected position of  FIG. 11A , so that it raises up the portion  131  of compliant membrane  130 , as well as the portion  133  that is inside inner boundary  152 . The maximum deflection at or near the inner boundary  152  is shown as δ=Δz. 
       FIG. 12A  shows a cross sectional view of an embodiment of a composite MEMS transducer having a cantilevered beam  120  extending across a portion of cavity  115 , where the cavity is a through hole from second surface  112  to first surface  111  of substrate  110 . As in the embodiment of  FIGS. 1 and 1B , compliant membrane  130  includes a first portion  131  that covers the MEMS transducing member, a second portion  132  that is anchored to first surface  111  of substrate  110 , and a third portion  133  that overhangs cavity  115  while not contacting the MEMS transducing member. Additionally in the embodiment of  FIG. 12A , the substrate further includes a second through hole  116  from second surface  112  to first surface  111  of substrate  110 , where the second through hole  116  is located near cavity  115 . In the example shown in  FIG. 12A , no MEMS transducing member extends over the second through hole  116 . In other embodiments where there is an array of composite MEMS transducers formed on substrate  110 , the second through hole  116  can be the cavity of an adjacent MEMS composite transducer. 
     The configuration shown in  FIG. 12A  can be used in a fluid ejector  200  as shown in  FIG. 12B . In  FIG. 12B , partitioning walls  202  are formed over the anchored portion  132  of compliant membrane  130 . In other embodiments (not shown), partitioning walls  202  are formed on first surface  111  of substrate  110  in a region where compliant membrane  130  has been removed. Partitioning walls  202  define a chamber  201 . A nozzle plate  204  is formed over the partitioning walls and includes a nozzle  205  disposed near second end  122  of the cantilevered beam  120 . Through hole  116  is a fluid feed that is fluidically connected to chamber  201 , but not fluidically connected to cavity  115 . Fluid is provided to cavity  201  through the fluid feed (through hole  116 ). When an electrical signal is provided to the MEMS transducing member (cantilevered beam  120 ) at an electrical connection region (not shown), second end  122  of cantilevered beam  120  and a portion of compliant membrane  130  are deflected upward and away from cavity  115  (as shown in  FIG. 2 ), so that a drop of fluid is ejected through nozzle  205 . 
     The embodiment shown in  FIG. 13  is similar to the embodiment of  FIG. 10 , where the MEMS transducing member is a clamped sheet  150 , but in addition, compliant membrane  130  includes a hole  135  at or near the center of cavity  115 . As also illustrated in  FIG. 14 , the MEMS composite transducer is disposed along a plane, and at least a portion of the MEMS composite transducer is movable within the plane. In particular, the clamped sheet  150  in  FIGS. 13 and 14  is configured to expand and contract radially, causing the hole  135  to expand and contract, as indicated by the double-headed arrows. Such an embodiment can be used in a drop generator for a continuous fluid jetting device, where a pressurized fluid source is provided to cavity  115 , and the hole  135  is a nozzle. The expansion and contraction of hole  135  stimulates the controllable break-off of the stream of fluid into droplets. Optionally, a compliant passivation material  138  can be formed on the side of the MEMS transducing material that is opposite the side that the portion  131  of compliant membrane  130  is formed on. Compliant passivation material  138  together with portion  131  of compliant membrane  130  provide a degree of isolation of the MEMS transducing member (clamped sheet  150 ) from the fluid being directed through cavity  115 . 
     A variety of transducing mechanisms and materials can be used in the MEMS composite transducer of the present invention. Some of the MEMS transducing mechanisms include a deflection out of the plane of the undeflected MEMS composite transducer that includes a bending motion as shown in  FIGS. 2 ,  8 B and  11 B. A transducing mechanism including bending is typically provided by a MEMS transducing material  160  in contact with a reference material  162 , as shown for the cantilevered beam  120  in  FIG. 15 . In the example of  FIG. 15 , the MEMS transducing material  160  is shown on top of reference material  162 , but alternatively the reference material  162  can be on top of the MEMS transducing material  160 , depending upon whether it is desired to cause bending of the MEMS transducing member (for example, cantilevered beam  120 ) into the cavity  115  or away from the cavity  115 , and whether the MEMS transducing material  160  is caused to expand more than or less than an expansion of the reference material  162 . 
     One example of a MEMS transducing material  160  is the high thermal expansion member of a thermally bending bimorph. Titanium aluminide can be the high thermal expansion member, for example, as disclosed in commonly assigned U.S. Pat. No. 6,561,627. The reference material  162  can include an insulator such as silicon oxide, or silicon oxide plus silicon nitride. When a current pulse is passed through the titanium aluminide MEMS transducing material  160 , it causes the titanium aluminide to heat up and expand. The reference material  160  is not self-heating and its thermal expansion coefficient is less than that of titanium aluminide, so that the titanium aluminide MEMS transducing material  160  expands at a faster rate than the reference material  162 . As a result, a cantilever beam  120  configured as in  FIG. 15  would tend to bend downward into cavity  115  as the MEMS transducing material  160  is heated. Dual-action thermally bending actuators can include two MEMS transducing layers (deflector layers) of titanium aluminide and a reference material layer sandwiched between, as described in commonly assigned U.S. Pat. No. 6,464,347. Deflections into the cavity  115  or out of the cavity can be selectively actuated by passing a current pulse through either the upper deflector layer or the lower deflector layer respectively. 
     A second example of a MEMS transducing material  160  is a shape memory alloy such as a nickel titanium alloy. Similar to the example of the thermally bending bimorph, the reference material  162  can be an insulator such as silicon oxide, or silicon oxide plus silicon nitride. When a current pulse is passed through the nickel titanium MEMS transducing material  160 , it causes the nickel titanium to heat up. A property of a shape memory alloy is that a large deformation occurs when the shape memory alloy passes through a phase transition. If the deformation is an expansion, such a deformation would cause a large and abrupt expansion while the reference material  162  does not expand appreciably. As a result, a cantilever beam  120  configured as in  FIG. 15  would tend to bend downward into cavity  115  as the shape memory alloy MEMS transducing material  160  passes through its phase transition. The deflection would be more abrupt than for the thermally bending bimorph described above. 
     A third example of a MEMS transducing material  160  is a piezoelectric material. Piezoelectric materials are particularly advantageous, as they can be used as either actuators or sensors. In other words, a voltage applied across the piezoelectric MEMS transducing material  160 , typically applied to conductive electrodes (not shown) on the two sides of the piezoelectric MEMS transducing material, can cause an expansion or a contraction (depending upon whether the voltage is positive or negative and whether the sign of the piezoelectric coefficient is positive or negative). While the voltage applied across the piezoelectric MEMS transducing material  160  causes an expansion or contraction, the reference material  162  does not expand or contract, thereby causing a deflection into the cavity  115  or away from the cavity  115  respectively. Typically in a piezoelectric composite MEMS transducer, a single polarity of electrical signal would be applied however, so that the piezoelectric material does not tend to become depoled. It is possible to sandwich a reference material  162  between two piezoelectric material layers, thereby enabling separate control of deflection into cavity  115  or away from cavity  115  without depoling the piezoelectric material. Furthermore, an expansion or contraction imparted to the MEMS transducing material  160  produces an electrical signal which can be used to sense motion. There are a variety of types of piezoelectric materials. One family of interest includes piezoelectric ceramics, such as lead zirconate titanate or PZT. 
     As the MEMS transducing material  160  expands or contracts, there is a component of motion within the plane of the MEMS composite transducer, and there is a component of motion out of the plane (such as bending). Bending motion (as in  FIGS. 2 ,  8 B and  11 B) will be dominant if the Young&#39;s modulus and thickness of the MEMS transducing material  160  and the reference material  162  are comparable. In other words, if the MEMS transducing material  160  has a thickness t 1  and if the reference material has a thickness t 2 , then bending motion will tend to dominate if t 2 &gt;0.5t 1  and t 2 &lt;2t 1 , assuming comparable Young&#39;s moduli. By contrast, if t 2 &lt;0.2t 1 , motion within the plane of the MEMS composite transducer (as in  FIGS. 13 and 14 ) will tend to dominate. 
     Some embodiments of MEMS composite transducer  100  include an attached mass, in order to adjust the resonant frequency for example (see equation 2 in the background). The mass  118  can be attached to the portion  133  of the compliant membrane  130  that overhangs cavity  115  but does not contact the MEMS transducing member, for example. In the embodiment shown in the cross-sectional view of  FIG. 16A  including a plurality of cantilevered beams  120  (such as the configuration shown in  FIG. 6 ), mass  118  extends below portion  133  of compliant membrane  130 , so that it is located within the cavity  115 . Alternatively, mass  118  can be affixed to the opposite side of the compliant membrane  130 , as shown in  FIG. 16B . The configuration of  FIG. 16A  can be particularly advantageous if a large mass is needed. For example, a portion of silicon substrate  110  can be left in place when cavity  115  is etched as described below. In such a configuration, mass  118  would typically extend the full depth of the cavity. In order for the MEMS composite transducer to vibrate without crashing of mass  118 , substrate  110  would typically be mounted on a mounting member (not shown) including a recess below cavity  115 . For the configuration shown in  FIG. 16B , the attached mass  118  can be formed by patterning an additional layer over the compliant membrane  130 . 
     Having described a variety of exemplary structural embodiments of MEMS composite transducers, a context has been provided for describing methods of fabrication.  FIGS. 17A to 17E  provide an overview of a method of fabrication. As shown in  FIG. 17A , a reference material  162  and a transducing material  160  are deposited over a first surface  111  of a substrate  110 , which is typically a silicon wafer. Further details regarding materials and deposition methods are provided below. The reference material  162  can be deposited first (as in  FIG. 17A ) followed by deposition of the transducing material  160 , or the order can be reversed. In some instances, a reference material might not be required. In any case, it can be said that the transducing material  160  is deposited over the first surface  111  of substrate  110 . The transducing material  160  is then patterned and etched, so that transducing material  160  is retained in a first region  171  and removed in a second region  172  as shown in  FIG. 17B . The reference material  162  is also patterned and etched, so that it is retained in first region  171  and removed in second region  172  as shown in  FIG. 17C . 
     As shown in  FIG. 17D , a polymer layer (for compliant membrane  130 ) is then deposited over the first and second regions  171  and  172 , and patterned such that polymer is retained in a third region  173  and removed in a fourth region  174 . A first portion  173   a  where polymer is retained is coincident with a portion of first region  171  where transducing material  160  is retained. A second portion  173   b  where polymer is retained is coincident with a portion of second region  172  where transducing material  160  is removed. In addition, a first portion  174   a  where polymer is removed is coincident with a portion of first region  171  where transducing material  160  is retained. A second portion  174   b  where polymer is removed is coincident with a portion of second region  172  where transducing material  160  is removed. A cavity  115  is then etched from a second surface  112  (opposite first surface  111 ) to first surface  111  of substrate  110 , such that an outer boundary  114  of cavity  115  at the first surface  111  of substrate  110  intersects the first region  171  where transducing material  160  is retained, so that a first portion of transducing material  160  (including first end  121  of cantilevered beam  120  in this example) is anchored to first surface  111  of substrate  110 , and a second portion of transducing material  160  (including second end  122  of cantilevered beam  120 ) extends over at least a portion of cavity  115 . When it is said that a first portion of transducing material  160  is anchored to first surface  111  of substrate  110 , it is understood that transducing material  160  can be in direct contact (not shown) with first surface  111 , or transducing material  160  can be indirectly anchored to first surface  111  through reference material  162  as shown in  FIG. 17E . A MEMS composite transducer  100  is thereby fabricated. 
     Reference material  162  can include several layers as illustrated in  FIG. 18A . A first layer  163  of silicon oxide can be deposited on first surface  111  of substrate  110 . Deposition of silicon oxide can be a thermal process or it can be chemical vapor deposition (including low pressure or plasma enhanced CVD) for example. Silicon oxide is an insulating layer and also facilitates adhesion of the second layer  164  of silicon nitride. Silicon nitride can be deposited by LPCVD and provides a tensile stress component that will help the transducing material  160  to retain a substantially flat shape when the cavity is subsequently etched away. A third layer  165  of silicon oxide helps to balance the stress and facilitates adhesion of an optional bottom electrode layer  166 , which is typically a platinum (or titanium/platinum) electrode for the case of a piezoelectric transducing material  160 . The platinum electrode layer is typically deposited by sputtering. 
     Deposition of the transducing material  160  will next be described for the case of a piezoelectric ceramic transducing material, such as PZT. An advantageous configuration is the one shown in  FIG. 18B  in which a voltage is applied across PZT transducing material  160  from a top electrode  168  to a bottom electrode  166 . The desired effect on PZT transducing material  160  is an expansion or contraction along the x-y plane parallel to surface  111  of substrate  110 . As described above, such an expansion or contraction can cause a deflection into the cavity  115  or out of the cavity  115  respectively, or a substantially in-plane motion, depending on the relative thicknesses and stiffnesses of the PZT transducing material  160  and the reference material  162 . Thicknesses are not to scale in  FIGS. 18A and 18B . Typically for a bending application where the reference material  162  has a comparable stiffness to the MEMS transducing material  160 , the reference material  162  is deposited in a thickness of about 1 micron, as is the transducing material  160 , although for in-plane motion the reference material thickness is typically 20% or less of the transducing material thickness, as described above. The transverse piezoelectric coefficients d 31  and e 31  are relatively large in magnitude for PZT (and can be made to be larger and stabilized if poled in a relatively high electric field). To orient the PZT crystals such that transverse piezoelectric coefficients d 31  and e 31  are the coefficients relating voltage across the transducing layer and expansion or contraction in the x-y plane, it is desired that the (001) planes of the PZT crystals be parallel to the x-y plane (parallel to the bottom platinum electrode layer  166  as shown in  FIG. 18B ). However, PZT material will tend to orient with its planes parallel to the planes of the material upon which it is deposited. Because the platinum bottom electrode layer  166  typically has its (111) planes parallel to the x-y plane when deposited on silicon oxide, a seed layer  167 , such as lead oxide or lead titanate can be deposited over bottom electrode layer  166  in order to provide the (001) planes on which to deposit the PZT transducing material  160 . Then the upper electrode layer  168  (typically platinum) is deposited over the PZT transducing material  160 , e.g. by sputtering. 
     Deposition of the PZT transducing material  160  can be done by sputtering. Alternatively, deposition of the PZT transducing material  160  can be done by a sal-gel process. In the sol-gel process, a precursor material including PZT particles in an organic liquid is applied over first surface  111  of substrate  110 . For example, the precursor material can be applied over first surface  111  by spinning the substrate  110 . The precursor material is then heat treated in a number of steps. In a first step, the precursor material is dried at a first temperature. Then the precursor material is pyrolyzed at a second temperature higher than the first temperature in order to decompose organic components. Then the PZT particles of the precursor material are crystallized at a third temperature higher than the second temperature. PZT deposited by a sol-gel process is typically done using a plurality of thin layers of precursor material in order to avoid cracking in the material of the desired final thickness. 
     For embodiments where the transducing material  160  is titanium aluminide for a thermally bending actuator, or a shape memory alloy such as a nickel titanium alloy, deposition can be done by sputtering. In addition, layers such as the top and bottom electrode layers  166  and  168 , as well as seed layer  167  are not required. 
     In order to pattern the stack of materials shown in  FIGS. 18A and 18B , a photoresist mask is typically deposited over the top electrode layer  168  and patterned to cover only those regions where it is desired for material to remain. Then at least some of the material layers are etched at one time. For example, plasma etching using a chlorine based process gas can be used to etch the top electrode layer  168 , the PZT transducing material  160 , the seed layer  167  and the bottom electrode layer  166  in a single step. Alternatively the single step can include wet etching. Depending on materials, the rest of the reference material  162  can be etched in the single step. However, in some embodiments, the silicon oxide layers  163  and  165  and the silicon nitride layer  164  can be etched in a subsequent plasma etching step using a fluorine based process gas. 
     Depositing the polymer layer for compliant membrane  130  can be done by laminating a film, such as TMMF, or spinning on a liquid resist material, such as TMMR, as referred to above. As the polymer layer for the compliant membrane is applied while the transducers are still supported by the substrate, pressure can be used to apply the TMMF or other laminating film to the structure without risk of breaking the transducer beams. An advantage of TMMR and TMMF is that they are photopatternable, so that application of an additional resist material is not required. An epoxy polymer further has desirable mechanical properties as mentioned above. 
     In order to etch cavity  115  ( FIG. 17E ) a masking layer is applied to second surface  112  of substrate  110 . The masking layer is patterned to expose second surface  112  where it is desired to remove substrate material. The exposed portion can include not only the region of cavity  115 , but also the region of through hole  116  of fluid ejector  200  (see  FIGS. 12A and 12B ). For the case of leaving a mass affixed to the bottom of the compliant membrane  130 , as discussed above relative to  FIG. 16A , the region of cavity  115  can be masked with a ring pattern to remove a ring-shaped region, while leaving a portion of substrate  110  attached to compliant membrane  130 . For embodiments where substrate  110  is silicon, etching of substantially vertical walls (portions  113  of substrate  110 , as shown in a number of the cross-sectional views including  FIG. 1B ) is readily done using a deep reactive ion etching (DRIE) process. Typically, a DRIE process for silicon uses SF 6  as a process gas. 
     As described above, one application for which MEMS composite transducer  100  is particularly well suited is as a drop generator  395  (also commonly referred to as a drop forming mechanism) in a continuous liquid ejection system  300 . Example embodiments of continuous liquid ejection systems are described in more detail below with reference to  FIGS. 19-31  and back to  FIGS. 13 and 14 . When used as the drop generator  395  (drop forming mechanism) in a continuous liquid ejection system, MEMS composite transducer  100  is included in a jetting module  305  (discussed in more detail below) of the continuous liquid ejection system  300 . 
     Generally referring to  FIGS. 19A-31  and back to  FIGS. 13 and 14 , jetting module  305  includes substrate  110  and an orifice plate  315 . Portions of substrate  110  define a liquid chamber  310 . Orifice plate  315  includes MEMS composite transducer  100  which includes a MEMS transducing member (a first MEMS transducing member in some example embodiments) and a compliant membrane  320 . The orifice plate is affixed to substrate  110 . Typically, compliant membrane  320  is a compliant polymeric membrane made from one of the polymers described above. However, compliant membrane  320  can be any of the compliant membranes described above depending on the specific application contemplated. 
     A first portion  121 ,  151  of the MEMS transducing member is anchored to substrate  110  and a second portion  122 ,  152  of the MEMS transducing member extends over at least a portion of liquid chamber  310 . The second portion  122 ,  152  of the MEMS transducing member is free to move relative to liquid chamber  310 . In  FIGS. 13 ,  14 ,  19 A, and  19 B, the MEMS transducing member includes clamped sheet  150 . In  FIGS. 20-23B , the MEMS transducing member includes cantilevered beam  120 . 
     A compliant membrane  320  is positioned in contact with the MEMS transducing member. A first portion  131  of compliant membrane  320  covers the MEMS transducing member and a second portion  132  of compliant membrane  320  is anchored to substrate  110 . Compliant membrane  320  includes an orifice  135 . 
     Continuous liquid ejection system  300  includes a liquid supply  325  (for example, liquid reservoir  335  and liquid pressure regulator  370  shown in  FIGS. 25 and 28 ) that provides a liquid to liquid chamber  310  under a pressure sufficient to eject a continuous jet  405  of the liquid (shown in  FIGS. 26A and 29 ) through orifice  135  located in compliant membrane  320  of orifice plate  315  (shown in  FIGS. 19A and 19B ). The MEMS transducing member is selectively actuated to cause a portion of compliant membrane  320  to be displaced relative to liquid chamber  310  causing a drop of liquid (shown in FIGS. X and Y) to break off from the liquid jet (shown in FIGS. X and Y). 
     Referring to  FIGS. 13 ,  14 ,  19 A, and  19 B, MEMS composite transducer  100  includes one MEMS transducing member in the form of a clamped sheet  150 . Compliant membrane  320  of orifice plate  315  is initially positioned in a plane, for example, a plane perpendicular to a direction of liquid jet ejection (shown using arrow  330 ) through orifice  135 . In  FIG. 14 , the MEMS transducing member, clamped sheet  150 , is configured to actuate in the plane of compliant membrane  320 . As described above, the MEMS transducing member motion will be predominantly in plane lacks a reference material, or the reference material has much less stiffness than the MEMS transducing material. As the MEMS transducing member is clamped sheet  150  that encircles orifice  135 , in-plane actuation of the MEMS transducing member (shown using the arrow included in  FIG. 14 ) modulates the geometry of orifice  135  causing a liquid drop to break off from the liquid jet. In  FIGS. 19A and 19B , the MEMS transducing member, clamped sheet  150 , is configured to actuate out of the plane of the compliant membrane  320 , the reference material having similar stiffness to the transducing material as described above. Drop generator  395  is shown at rest in  FIG. 19A . 
     Expansion or contraction of the MEMS transducing member causes deflection of compliant membrane  320  (and the MEMS transducing member) into liquid chamber  310  or out of liquid chamber  310  (shown in  FIG. 19B ) causing a liquid drop to break off from the liquid jet. The MEMS clamped sheet transducing member  150 , is shown at rest in  FIG. 19A  and actuated in  FIG. 19B  with deflection of compliant membrane  320  (and the MEMS transducing member) out of liquid chamber  310 . 
     Referring to  FIGS. 20-23B , MEMS composite transducer  100  includes a plurality of MEMS transducing members, a first MEMS transducing member (described above) and a similar second MEMS transducing member. Similar to the first MEMS transducing member, a first portion  121  of the second MEMS transducing member is anchored to substrate  110 . A second portion  122  of the second MEMS transducing member extends over at least a portion of liquid chamber  310 . The second portion  122  of the second MEMS transducing member is free to move relative to liquid chamber  310 . 
     In addition to its configuration relative to the first MEMS transducing member (described above), compliant membrane  320  is similarly positioned in contact with the second MEMS transducing member. A first portion  131  of the compliant membrane covers the second MEMS transducing member and a second portion  132  of compliant membrane  320  is anchored to substrate  110 . In  FIGS. 20-23B , the first MEMS transducing member is cantilevered beam  120  and the second MEMS transducing member is cantilevered beam  120 . The first MEMS transducing member and the second MEMS transducing member are symmetrically positioned relative to orifice  135  of compliant membrane  320 . 
     When MEMS composite transducer  100  includes a plurality of MEMS transducing members, the capabilities of jetting module  305  are increased when compared to jetting modules that do not include a plurality of MEMS transducing members. When so configured, jetting module  305  has the ability to only create (form) liquid drops from the liquid jet ejected through orifice  135  or to create and steer liquid drops from the liquid jet ejected through orifice  135 . 
     Referring to  FIGS. 21A ,  21 B, and  21 C, when it is desired to only create drops, the plurality of MEMS transducing members of MEMS composite transducer  100 , symmetrically positioned relative to orifice  135  of compliant membrane  320 , are actuated simultaneously. Simultaneous actuation of the plurality of MEMS transducing members does not alter the trajectory of the liquid jet that is ejected through orifice  135 . Typically, the trajectory of the liquid jet is perpendicular to orifice plate  315  when the initial position of orifice plate  315  is in a plane perpendicular to a direction of liquid jet ejection (shown using arrow  330 ) through orifice  135 . 
     Drop generator  395  is shown at rest in  FIG. 21A . Actuation of the plurality of MEMS transducing members is in the same direction either in-plane (shown in  FIG. 21B ) or out of plane (shown in  FIG. 21C ) relative to compliant membrane  320 . Again, the plane referred to here is the plane in which compliant membrane  320  of orifice plate  315  is initially positioned, for example, a plane perpendicular to a direction of liquid jet ejection (shown using arrow  330 ) through orifice  135 . As with the clamped sheet configuration discussed above, in-plane actuation of the plurality of MEMS transducing members modulates the geometry of orifice  135  causing a liquid drop to break off from the liquid jet. Alternatively, out of plane actuation by expanding or contracting the plurality of MEMS transducing members, having reference materials of appropriate stiffness, results in deflection of compliant membrane  320  (and the. MEMS transducing member) into liquid chamber  310  or out of liquid chamber  310 ) causing a liquid drop to break off from the liquid jet. The MEMS transducing members  120 , are shown at rest in  FIG. 21A  and actuated in  FIG. 21C  with deflection of compliant membrane  320  (and the MEMS transducing member) out of liquid chamber  310 . 
     Referring to  FIGS. 22-23B , when it is desired to create and steer drops, the plurality of MEMS transducing members of MEMS composite transducer  100 , symmetrically positioned relative to orifice  135  of compliant membrane  320 , are actuated either simultaneously in different, for example, opposite, directions or asynchronously. Actuation of the plurality of MEMS transducing members is out of plane relative to compliant membrane  320 . Again, the plane referred to here is the plane in which compliant membrane  320  of orifice plate  315  is initially positioned, for example, a plane perpendicular to a direction of liquid jet ejection (shown using arrow  330 ) through orifice  135 . 
     Out of plane actuation by expanding or contracting the plurality of MEMS transducing members either simultaneously in different, for example, opposite, directions or asynchronously results in deflection of compliant membrane  320  (and the MEMS transducing member) into liquid chamber  310  or out of liquid chamber  310  which causes the deflection of the ejected liquid jet and causes a liquid drop to break off from the liquid jet. In addition to creating a liquid drop from the liquid jet, the initial trajectory of the ejected liquid jet is altered by the out of plane actuation of the plurality of MEMS transducing members or of one of the plurality of MEMS transducing members. 
     Typically, the initial trajectory of the liquid jet is perpendicular to orifice plate  315  when the initial position of orifice plate  315  is in a plane perpendicular to a direction of liquid jet ejection (shown using arrow  330 ) through orifice  135 . When, for example, the plurality of MEMS transducing members are actuated simultaneously in opposite directions, the trajectory of the liquid jet is altered such that the trajectory of the liquid jet is at a non-perpendicular angle relative to the initial trajectory of the liquid jet or the initial position of orifice plate  315 . The drop that breaks off from the deflected liquid jet travels along the altered trajectory of the liquid jet. In  FIG. 22 , the pair of solid line arrows illustrates one way to actuate the drop generator and the pair of dashed line arrows illustrates another way to actuate the drop generator. Similar results occur when first MEMS transducing member is actuated asynchronously relative to the second MEMS transducing member. In  FIG. 23A , the first MEMS transducing member is actuated by itself either in the direction indicated by the solid line arrow or the direction indicated by the dashed line arrow to achieve drop steering in a first direction. The second MEMS transducing member is actuated by itself either in the direction indicated by the solid line arrow or the direction indicated by the dashed line arrow to achieve drop steering in a second direction. Accordingly, drop steering is effected MEMS composite transducer  100  drop generator of jetting module  305 . 
     The ability to steer drops offers several benefits. For example, drop steering can be used to differentiate between print drops and non-print drops. Alternatively, drop steering can be used to maintain print quality by correcting liquid jets that lack sufficient straightness caused by an accumulation of dust, dirt, or debris on orifice plate  315  or resulting from a manufacturing defect in jetting module  305 . 
     Referring to  FIGS. 24A and 24B , and back to  FIGS. 3 and 4 , respectively, positioning additional MEMS transducing members, for example, cantilevered beams  120 , symmetrically relative to orifice  135  increases the ability of jetting module  305  to control drop steering. As shown in  FIGS. 24A and 24B , four MEMS transducing members are included in orifice plate  315  which provides drop steering in directions along the positioning of each MEMS transducing member as well as in directions between adjacent MEMS transducing members. 
     Additionally, the frequency response of the jetting module shown in  FIG. 24B  is increased when compared to the frequency response of the jetting module shown in  FIG. 24A  because the MEMS transducing members included in the orifice plate shown in  FIG. 24B  stiffen orifice plate  315  by occupying and contacting a greater area of compliant membrane  320  when compared to occupation and contact area of the MEMS transducing members relative to the compliant membrane  320  shown in  FIG. 24A . 
     The drop that breaks off from the liquid jet, described above, is one of a plurality of drops traveling along a first path. Continuous liquid ejection system  300  includes a deflection mechanism and a catcher. The deflection mechanism is positioned to deflect selected drops of the plurality of drops traveling along the first path such that the selected drops begin traveling along a second path. The catcher is positioned to intercept drops traveling along one of the first path and the second path. 
     Drops created using these types of drop generators can be are deflected using electrostatic deflection or gas flow deflection. When electrostatic deflection is included in continuous liquid ejection system  300 , the deflection mechanism typically includes one electrode or two electrodes. When one electrode is used, the electrode electrically charges and deflects the selected drops such that the deflected drops begin traveling along the second path. When two electrodes are used, a first electrode electrically charges the selected drops and a second electrode deflects the selected drops such that the deflected drops begin traveling along the second path. When gas flow deflection is included in continuous liquid ejection system  300 , each drop of the plurality of drops has one of a first size and a second size and the deflection mechanism includes a gas flow that deflects at least the drops having the first size such that the drops having the first size begin traveling along the second path. These aspects of continuous liquid ejection system  300  are described in more detail below with reference to  FIGS. 25-30 . 
     Referring to  FIGS. 25-27B , an example embodiment of a continuous liquid ejection system  300  that deflects selected drops using electrostatic deflection is shown. Continuous liquid ejection system  300  includes a liquid reservoir  335  that continuously pumps ink to printhead  375  that ultimately creates a continuous stream of liquid, for example, ink, drops. Continuous liquid ejection system  300  receives digitized image process data from an image source  340 , for example, a scanner, digital camera, computer, or other source of digital data which provides raster image data, outline image data in the form of a page description language, or other forms of digital image data. The image data from the image source  340  is sent periodically to an image processor  345 . Image processor  345  processes the image data and includes a memory for storing image data. The image processor  345  is typically a raster image processor (RIP). The RIP or other type of image processor  345  converts the image data to a pixel-mapped image page image for printing. Image data in image processor  345  is stored in image memory in the image processor  345  and is sent periodically to a drop or stimulation controller  350  which generates patterns of time-varying electrical stimulation pulses to cause a stream of drops to form liquid jets ejected through each of the nozzle orifices included in jetting module  305 . These stimulation pulses are applied at an appropriate time and at an appropriate frequency to drop generator(s) associated with each of the orifices of jetting module  305   
     Jetting module  305  and deflection mechanism  355  of printhead  375  work in concert with each other in order to determine whether liquid, for example, ink, drops are printed on a recording medium  360  in the appropriate position designated by the data in image memory or deflected and recycled via the liquid recycling units  365 . The liquid in the recycling units  365  is directed back into the reservoir  335 . The liquid is distributed under pressure through a back surface of jetting module  305  in printhead  375  to a liquid channel in jetting module  305  that includes a chamber or plenum formed in a silicon substrate. Alternatively, the liquid chamber is formed in a manifold piece to which the silicon substrate is affixed. The liquid preferably flows from the chamber through slots or holes etched through the silicon substrate of jetting module  305  to its front surface, where a plurality of orifices and associated drop generators are situated. The liquid pressure suitable for optimal operation depends on a number of factors, including orifice geometry and fluid dynamic properties of the liquid. Constant liquid pressure is achieved by applying pressure to reservoir  335  under the control of a pressure regulator  370 . 
     During a liquid ejection operation, for example, an ink printing operation, a recording medium  360  is moved relative to printhead  375  by a recording medium transport system  380 , including a plurality of transport rollers as shown in  FIG. 25 , which is electronically controlled by a transport control system  385 . A logic controller  390 , preferably micro-processor based and suitably programmed as is well known, provides control signals for cooperation of transport control system  385  with pressure regulator  370  and stimulation controller  350 . The stimulation controller  350  includes a drop controller that provides the drive signals for creating individual liquid drops from printhead  375  that travel to recording medium  360  according to the image data obtained from an image memory forming part of the image processor  345 . Image data includes raw image data, additional image data generated from image processing algorithms to improve the quality of printed images, or data from drop placement corrections, which can be generated from many sources, for example, from measurements of the steering errors of liquid ejected through each orifice in jetting module  305  as is well-known to those skilled in the art of printhead characterization and image processing. As such, the information in the image processor  345  is said to represent a general source of data for liquid drop ejection, such as desired locations of ink drops to be printed and identification of those drops to be collected for recycling. 
     Depending on the application contemplated, different mechanical configurations for receiver transport control are used. For example, when printhead  375  is a page-width printhead  375 , it is convenient to move recording medium  360  past a stationary printhead  375 . On the other hand, in a scanning-type printing system, it is more convenient to move printhead  375  along one axis (a main-scanning direction) and move the recording medium along an orthogonal axis (a sub-scanning direction), in relative raster motion. 
     Drop forming pulses are provided by the stimulation controller  350 , commonly referred to as drop controller, and are typically voltage pulses sent to printhead  375  through electrical connectors, as is well-known in the art of signal transmission. Once formed, printing drops travel through the air to recording medium  360  and impinge on a particular pixel area of recording medium  360  while non-printing drops are collected by a catcher described below. 
     Referring to  FIGS. 26A and 26B , a continuous liquid ejection printhead  375  is shown. A drop generator  395  causes liquid drops  400  to break off from a liquid jet  405  ejected through orifice  135 . Selection of drops  400  as print drops  410  or non-print drops  415  depends on the phase of the drop break off relative to the charge electrode voltage pulses that are applied to the to a charge electrode  420  that is part of a deflection mechanism  425 . The charge electrode  420  is variably biased by a charging pulse source  430  which provides a sequence of charging pulses that is periodic with a fixed frequency. 
     The charging pulse train preferably includes rectangular voltage pulses having a low level that is grounded relative to the printhead  375  and a high level biased sufficiently to charge the drops  400  as they break off. An exemplary range of values of the electrical potential difference between the high level voltage and the low level voltage is 50 to 200 volts and more preferably 90 to 150 volts. 
     When a relatively high level voltage or electrical potential is applied to the charge electrode  420  as a drop  400  breaks off from the liquid jet  405  in front of the charge electrode  420  (as shown in  FIG. 3A ), the drop  400  acquires a charge and is deflected toward a catcher  435 . Drops  415  that strike the face  440  of catcher  435  form a liquid film  445  on the face  440  of catcher  435 . 
     Deflection occurs when drops  400 ;  415  break off the liquid jet  405  while the potential of the charge electrode or electrodes  420  is provided with a voltage or electrical potential having a non-zero magnitude. The drops  400  then acquire an induced electrical charge that remains upon the drop surface. The charge on an individual drop  400  has a polarity opposite that of the charge electrode and a magnitude that is dependent upon the magnitude of the voltage and the capacity of coupling between the charge electrode and the drop  400  at the instant the drop  400  separates from the liquid jet  405 . This capacity of coupling is dependent in part on the spacing between the charge electrode  420  and the drop  400  as the drop  400  is breaking off. Once the charged drops  400  have broken away from the liquid jets  405 , the drops  400  travel in close proximity to the catcher face  440  which is typically constructed of a conductor or dielectric. The charges on the surface of the drop  400  induce either a surface charge density charge (for the catcher  435  constructed of a conductor) or a polarization density charge (for the catcher  435  constructed of a dielectric). The induced charges in the catcher  435  produce an electric field distribution identical to that produced by a fictitious charge (opposite in polarity and equal in magnitude) located a distance inside the catcher  435  equal to the distance between the catcher  435  and the drop  400 . These induced charges in the catcher  435  are known in the art as an image charge. The force exerted on the charged drop  400  by the catcher face  440  is equal to what would be produced by the image charge alone and causes the charged drops  400  to deflect and thus diverge from its path and accelerate along a trajectory toward the catcher face  440  at a rate proportional to the square of the drop charge and inversely proportional to the drop mass. In this embodiment, the charge distribution induced on the catcher  435  makes up a portion of the deflection mechanism  425 . In other embodiments, the deflection mechanism  425  includes one or more additional electrodes to generate an electric field through which the charged drops pass so as to deflect the charged drops. For example, a single biased electrode in front of the upper grounded portion of the catcher is used and described in U.S. Pat. No. 4,245,226. A pair of additional electrodes are used and described in U.S. Pat. No. 6,273,559 
     Referring to  FIG. 26B , when the break off point of drop  400  from liquid jet  405  occurs when the electrical potential of the charge electrode  420  is at a relatively low level or zero, the drop  400 ;  410  does not acquire a charge. Drop  400 ;  410  travels along a trajectory which is typically an undeflected path and impacts recording medium  360 . 
     Referring to  FIGS. 27A and 27B , a printhead  375  similar to that described with reference to  FIGS. 26A and 26B  is shown. In this embodiment, however, the deflection mechanism  425  also includes a second charge electrode  420 A located on the opposite side of the jet array  405  from the (first) charge electrode  420 . Second charge electrode  420 A receives the same charging pulses from the charge pulse source  430  as first charge electrode  420  and is constantly held at the same potential as first charge electrode  420 . The addition of a second charge electrode  420 A biased to the same potential as first charge electrode  420  produces a region between the charging electrodes  420  and  420 A with a very uniform electric field. Placement of the drop breakoff points between these charge electrodes makes the drop charging and subsequent drop deflection very insensitive to the small changes in breakoff position relative to the charging electrodes or to the small changes in the electrode geometries. This configuration is therefore much more suitable for use with printheads  375  having long arrays of orifices  135 . 
     The deflection mechanism  425  also includes a deflection electrode  450 . The voltage potential between the biased deflection electrode  450  and the catcher face  440  produces an electric field through which the drops  400  must pass. Charged non-print drops  415  are deflected by this electric field and strike the catcher face  440 .  FIGS. 27A and 27B  also show a graph illustrating the voltage or electrical potential on the charge electrode  420  and second charge electrode  420 A at the respective times when a drop  400  breaks off. The periodicity of the electrical potential on the charge electrode  420  and  420 A is synchronized with the pulse stimulation signals provided to the drop generator  395  located at each orifice  135 . 
     Alternatively, electrostatic deflection can be accomplished using individual charging electrodes with one electrode being associated with a corresponding one of the orifices  135  of the orifice array. The individually associated electrodes can charge and deflect selected drops either alone, as described above with reference to  FIGS. 26A and 26B , or in combination with separate deflection electrodes, as described above with reference to  FIGS. 27A and 27B . These types of electrostatic deflection systems have been described in U.S. Pat. No. 7,273, 270, issued on Sep. 25, 2007, to Katerberg; and in U.S. Pat. No. 7,673,976, issued on Mar. 9, 2010, to Piatt et al. 
     Referring to  FIGS. 28-30 , an example embodiment of a continuous liquid ejection system  300  that deflects drops using gas flow deflection is shown. Continuous liquid ejection system  300  includes an image source  340 , for example, a scanner or computer which provides raster image data, outline image data in the form of a page description language, or other forms of digital image data. The image data is converted to half-toned bitmap image data by an image processing unit  345  which also stores the image data in memory. A plurality of control circuits  455  read data from the image memory and applies time-varying electrical pulses to a drop generators  395  each associated with an orifice of printhead  375 . The pulses are applied at an appropriate time, and to the appropriate drop generator  395 , so that drops that break off from a continuous liquid jet form spots on recording medium  360  in the appropriate position designated by the data in the image memory. 
     Recording medium  360  is moved relative to printhead  375  by a recording medium transport system  380 , which is electronically controlled by a recording medium transport control system  385  which is controlled by a micro-controller  390 . The recording medium transport system  380  shown in  FIG. 28  is a schematic only, and many different mechanical configurations are possible. For example, a transfer roller is used in some applications as recording medium transport system  380  to facilitate transfer of drops to recording medium  360 . Such transfer roller technology is well known in the art. When printhead  375  is a page width printheads  375 , it is most convenient to move recording medium  360  past a stationary printhead. However, when printhead  375  is a scanning type printhead, it is usually most convenient to move printhead  375  along one axis (the main scanning direction) and recording medium  360  along an orthogonal axis (the sub-scanning direction) in a relative raster motion. 
     Liquid, for example, ink, is contained in a liquid supply  335  under pressure. In the non-printing state, continuous liquid drop streams are unable to reach recording medium  360  due to a catcher  435  that collects the drops for recycling by a recycling unit  365 . Recycling unit  365  reconditions the liquid and feeds it back to reservoir  335 . Such recycling units are well known in the art. The liquid pressure suitable for optimal operation depends on a number of factors, including orifice geometry and properties of the liquid. A constant liquid pressure is achieved by applying pressure to reservoir  335  under the control of liquid pressure regulator  370 . Alternatively, the reservoir  335  can be left unpressurized, or even under a reduced pressure (vacuum), while a pump is used to deliver liquid from reservoir  335  under pressure to printhead  375 . In this example embodiment, pressure regulator  370  typically includes a liquid pump control system. As shown in  FIG. 28 , catcher  435  is a type of catcher commonly referred to as a “knife edge” catcher. 
     Liquid is distributed through a back surface of printhead  375  through a liquid channel  460  located in jetting module  305 . The liquid preferably flows through slots or holes etched through a silicon substrate of printhead  375  to its front surface, where a plurality of orifices and associated drop generators are situated. When printhead  375  is fabricated from silicon, drop generator control circuits  455  can be integrated with printhead  375 . Printhead  375  also includes a deflection mechanism which is described in more detail below with reference to  FIGS. 29 and 30 . 
     Referring to  FIG. 29 , a schematic view of a continuous liquid ejection printhead  375  is shown. A jetting module  305  of printhead  375  includes an array or a plurality of nozzles orifices  135  formed in an orifice plate  315 . In  FIG. 29 , nozzle plate  315  is affixed to jetting module  305 . However, as shown in  FIG. 30 , nozzle plate  315  is an integral portion of jetting module  305 . Liquid, for example, ink, is ejected under pressure through each orifice  135  of the array to form jets  405  of liquid. In  FIG. 29 , the array or plurality of orifices  135  extends into and out of the figure. 
     The plurality of control circuits  455  read data from the image memory and apply time-varying electrical pulses to each drop generator  395  to form liquid drops  400  having a first size (or volume)  465  and liquid drops having a second size (or volume)  470  from each liquid jet. To accomplish this, jetting module  305  includes a drop generator (or drop forming device)  395 , described above, that, when activated, perturbs each jet  405  of liquid, for example, ink, to induce portions of each jet to breakoff from the jet and coalesce to form drops  465  and  470 . One drop generator  395  is associated with each orifice  135  of the orifice array. The application of time-varying electrical pulses to each drop generator  395  using control circuits  455  is known with certain aspects having been described in, for example, one or more of U.S. Pat. No. 6,491,362 B1, issued to Jeanmaire, on Dec. 10, 2002; U.S. Pat. No. 6,554,410 B2, issued to Jeanmaire et al., on Apr. 29, 2003; U.S. Pat. No. 6,575,566 B1, issued to Jeanmaire et al., on Jun. 10, 2003; U.S. Pat. No. 6,588,888 B2, issued to Jeanmaire et al., on Jul. 8, 2003; U.S. Pat. No. 6,793,328 B2, issued to Jeanmaire, on Sep. 21, 2004; and U.S. Pat. No. 6,851,796 B2, issued to Jeanmaire et al., on Feb. 8, 2005. 
     When printhead  375  is in operation, drops  465 ,  470  are created in a plurality of sizes or volumes, for example, drops having a first size or volume (small drops)  465  and drops having a second size or volume (large drops) 470 . The ratio of the mass of the large drops  470  to the mass of the small drops  465  is typically an integer between 2 and 10. A drop stream  475  including drops  465  and  470  travels along a drop path or trajectory  480 . 
     Printhead  375  also includes a gas flow deflection mechanism  485  that directs a flow of gas  490 , for example, air, through gas flow ducts  515 ,  520  and past a portion of the drop trajectory  480  commonly referred to as a deflection zone  495 . As the flow of gas  490  interacts with drops  465 ,  470  in deflection zone  495  it alters the drop trajectories. As the drops  465 ,  470  pass out of the deflection zone  495  they are traveling at an altered trajectory that is at an angle, often referred to as a deflection angle, relative to the undeflected drop trajectory  480 . 
     Small drops  465  are more affected by the flow of gas than are large drops  470  so that the resulting small drop trajectory  500  diverges from the large drop trajectory  505 . That is, the deflection angle for small drops  465  is larger than for large drops  470 . The flow of gas  490  provides sufficient drop deflection and therefore causes sufficient divergence of the small and large drop trajectories so that catcher  435  (shown in  FIGS. 28 and 30 ), positioned to intercept drops traveling along one of the small drop trajectory  500  and the large drop trajectory  505 , collects drops traveling along one of the trajectories while allowing drops following the other trajectory to impinge recording medium  360  (shown in  FIGS. 28 and 30 ). 
     Referring to  FIG. 30 , a positive pressure gas flow structure  510  of gas flow deflection mechanism  485  is located on a first side of drop trajectory  480 . Positive pressure gas flow structure  510  includes a first gas flow duct  515  that includes a lower wall  525  and an upper wall  530 . Gas flow duct  515  directs gas flow  490  supplied from a positive pressure source  535  at downward angle  0  of approximately a  45 ° relative to liquid jet  405  toward drop deflection zone  495  (shown in  FIG. 2 ). An optional seal(s)  540  provides a fluid seal between jetting module  305  and upper wall  530  of gas flow duct  515 . 
     Upper wall  530  of gas flow duct  515  does not need to extend to drop deflection zone  495  (as shown in  FIG. 29 ). In  FIG. 30 , upper wall  530  ends at a wall  545  of jetting module  305 . Wall  545  of jetting module  305  serves as a portion of upper wall  530  ending at drop deflection zone  495 . 
     Negative pressure gas flow structure  550  of gas flow deflection mechanism  485  is located on a second side of drop trajectory  480 . Negative pressure gas flow structure  550  includes a second gas flow duct  520  located between catcher  435  and an upper wall  555  that exhausts gas flow from deflection zone  495 . Second duct  520  is connected to a negative pressure source  560  that is used to help remove gas flowing through second duct  520 . An optional seal(s)  540  provides a fluid seal between jetting module  305  and upper wall  555 . 
     As shown in  FIG. 30 , gas flow deflection mechanism  485  includes positive pressure source  535  and negative pressure source  560 . However, depending on the specific application contemplated, gas flow deflection mechanism  485  includes only one of positive pressure source  535  and negative pressure source  560 . 
     In operation, gas supplied by first gas flow duct  515  is directed into drop deflection zone  495 , where it causes large drops  470  to follow large drop trajectory  505  and small drops  465  to follow small drop trajectory  500 . As shown in  FIG. 3 , drops  465  traveling along small drop trajectory  500  are intercepted by a front face  440  of catcher  435 . Small drops  465  contact face  440  and flow down face  440  and into a liquid return duct  565  located or formed between catcher  435  and a plate  570 . Collected liquid is either recycled and returned to reservoir  335  (shown in  FIG. 1 ) for reuse or discarded. Large drops  470  bypass catcher  435  and travel to recording medium  360 . Alternatively, catcher  435  can be positioned to intercept drops  470  traveling along large drop trajectory  505 . Large drops  470  contact catcher  435  and flow into liquid return duct  565  located or formed in catcher  435 . Collected liquid is either recycled for reuse or discarded. Small drops  465  bypass catcher  435  and travel to recording medium  360 . 
     As shown in  FIG. 30 , catcher  435  is a type of catcher commonly referred to as a “Coanda” catcher. However, the “knife edge” catcher shown in  FIG. 28  and the “Coanda” catcher shown in  FIG. 30  are interchangeable and either can be used with the selection typically depending on the application contemplated. Alternatively, catcher  435  can be of any suitable design including, but not limited to, a porous face catcher, a delimited edge catcher, or combinations of any of those described above. 
     Referring to  FIG. 31 , an example embodiment of a method of continuously ejecting liquid using the continuous liquid ejection system described above is shown. The method begins with step  600 . 
     In step  600 , a continuous liquid ejection system is provided. The system includes a substrate and an orifice plate affixed to the substrate. Portions of the substrate define a liquid chamber. The orifice plate includes a MEMS transducing member. A first portion of the MEMS transducing member is anchored to the substrate. A second portion of the MEMS transducing member extends over at least a portion of the liquid chamber. The second portion of the MEMS transducing member is free to move relative to the liquid chamber. A compliant membrane is positioned in contact with the MEMS transducing member. A first portion of the compliant membrane covers the MEMS transducing member and a second portion of the compliant membrane is anchored to the substrate. The compliant membrane includes an orifice. Step  600  is followed by step  605 . Typically, the compliant membrane is a compliant polymeric membrane made from one of the polymers described above. However, compliant membrane can be any of the compliant membranes described above depending on the specific application contemplated. 
     In step  605 , a liquid is provided under a pressure sufficient to eject a continuous jet of the liquid through the orifice located in the compliant membrane of the orifice plate by a liquid supply. Step  605  is followed by step  610 . 
     In step  610 , a drop of liquid is caused to break off from the liquid jet by selectively actuating the MEMS transducing member which causes a portion of the compliant membrane to be displaced relative to the liquid chamber. Step  610  is followed by step  615  and step  625 . 
     In step  625 , optionally, the formed drop is steered by the MEMS transducing member. Step  625  is followed by step  615 . 
     In step  615 , the drop is one of a plurality of drops traveling along a first path. An appropriately positioned deflection mechanism deflects selected drops of the plurality of drops traveling along the first path such that the selected drops begin traveling along a second path. Step  615  is followed by step  620 . 
     In step  620 , an appropriately positioned catcher intercepts drops traveling along one of the first path and the second path. 
     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 
     
         
         
           
               100  MEMS composite transducer 
               110  substrate 
               111  first surface of substrate 
               112  second surface of substrate 
               113  portions of substrate (defining outer boundary of cavity) 
               114  outer boundary 
               115  cavity 
               116  through hole (fluid inlet) 
               118  mass 
               120  cantilevered beam 
               121  anchored end (of cantilevered beam) 
               122  cantilevered end (of cantilevered beam) 
               130  compliant membrane 
               131  covering portion of compliant membrane 
               132  anchoring portion of compliant membrane 
               133  portion of compliant membrane overhanging cavity 
               134  portion where compliant membrane is removed 
               135  hole (in compliant membrane), orifice 
               138  compliant passivation material 
               140  doubly anchored beam 
               141  first anchored end 
               142  second anchored end 
               143  intersection region 
               150  clamped sheet 
               151  outer boundary (of clamped sheet) 
               152  inner boundary (of clamped sheet) 
               160  MEMS transducing material 
               162  reference material 
               163  first layer (of reference material) 
               164  second layer (of reference material) 
               165  third layer (of reference material) 
               166  bottom electrode layer 
               167  seed layer 
               168  top electrode layer 
               171  first region (where transducing material is retained) 
               172  second region (where transducing material is removed) 
               200  fluid ejector 
               201  chamber 
               202  partitioning walls 
               204  nozzle plate 
               205  nozzle 
               300  continuous liquid ejection system 
               305  jetting module 
               310  liquid chamber 
               315  orifice plate 
               320  compliant membrane 
               325  liquid supply 
               330  liquid ejection arrow 
               335  liquid reservoir 
               340  image source 
               345  image processor 
               350  stimulation controller 
               355  deflection mechanism 
               360  recording medium 
               365  liquid recycling units 
               370  pressure regulator 
               375  printhead 
               380  recording medium transport system 
               385  recording medium transport control system 
               390  logic controller 
               395  drop generator 
               400  liquid drops 
               405  liquid jet 
               410  print drops 
               415  non-print drops 
               420  charge electrode 
               420 A second charge electrode 
               425  deflection mechanism 
               430  charging pulse source 
               435  catcher 
               440  face 
               445  liquid film 
               450  deflection electrode 
               455  plurality of control circuits 
               460  liquid channel 
               465  drops 
               470  drops 
               475  drop stream 
               480  trajectory 
               485  gas flow deflection mechanism 
               490  gas flow 
               495  deflection zone 
               500  small drop trajectory 
               505  large drop trajectory 
               510  positive pressure gas flow structure 
               515  gas flow ducts 
               520  gas flow ducts 
               525  lower wall 
               530  upper wall 
               535  positive pressure source 
               545  wall 
               550  negative pressure gas flow structure 
               555  upper wall 
               560  negative pressure source 
               565  liquid return duct 
               570  plate 
               600  provide continuous liquid ejection system 
               605  provide pressurized liquid 
               610  drop formation 
               615  selected drop deflection 
               620  drop interception 
               625  optional drop steering