WO2012145260A1 - Système d'éjection continue comprenant un transducteur à membrane déformable - Google Patents

Système d'éjection continue comprenant un transducteur à membrane déformable Download PDF

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Publication number
WO2012145260A1
WO2012145260A1 PCT/US2012/033733 US2012033733W WO2012145260A1 WO 2012145260 A1 WO2012145260 A1 WO 2012145260A1 US 2012033733 W US2012033733 W US 2012033733W WO 2012145260 A1 WO2012145260 A1 WO 2012145260A1
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WO
WIPO (PCT)
Prior art keywords
mems transducing
transducing member
compliant membrane
drops
mems
Prior art date
Application number
PCT/US2012/033733
Other languages
English (en)
Inventor
Michael Frank Baumer
James D. Huffman
Hrishikesh V. Panchawagh
Jeremy Matthew Grace
Yonglin Xie
Qing Yang
David Paul Trauernicht
John Andrew Lebens
Original Assignee
Eastman Kodak Company
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US13/089,521 external-priority patent/US8398210B2/en
Priority claimed from US13/089,594 external-priority patent/US8529021B2/en
Application filed by Eastman Kodak Company filed Critical Eastman Kodak Company
Priority to CN201280030136.6A priority Critical patent/CN103619598A/zh
Priority to EP12719833.1A priority patent/EP2699423A1/fr
Publication of WO2012145260A1 publication Critical patent/WO2012145260A1/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
    • B41J2/01—Ink jet
    • B41J2/135—Nozzles
    • B41J2/14—Structure thereof only for on-demand ink jet heads
    • B41J2/14427—Structure of ink jet print heads with thermal bend detached actuators
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
    • B41J2/01—Ink jet
    • B41J2/135—Nozzles
    • B41J2/14—Structure thereof only for on-demand ink jet heads
    • B41J2/14427—Structure of ink jet print heads with thermal bend detached actuators
    • B41J2002/14435—Moving nozzle made of thermal bend detached actuator

Definitions

  • 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.
  • Inkjet 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.
  • Inkjet printing mechanisms can be categorized by technology as either drop on demand ink jet (DOD) or continuous ink jet (CIJ).
  • DOD drop on demand ink jet
  • CIJ continuous ink jet
  • 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.
  • 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)."
  • Micro-Electro-Mechanical Systems 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.
  • a liquid supply provides a liquid to the liquid chamber under a pressure sufficient to eject a continuous jet of the liquid through the orifice located in the compliant membrane of the orifice plate.
  • the MEMS transducing member is selectively actuated to cause a portion of the compliant membrane to be displaced relative to the liquid chamber to cause a drop of liquid to break off from the liquid jet.
  • FIG. 3 is a top view of an embodiment similar to FIG. 1 A, 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. 8A is a cross-sectional view of the MEMS composite transducer of FIG. 7 in its undeflected state
  • FIG. 11 A is a cross-sectional view of the MEMS composite transducer of FIG. 10 in its undeflected state
  • FIG. 1 IB 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
  • 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
  • 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. 21 A is a schematic cross-sectional view of the example embodiment shown in FIG. 20;
  • FIG. 2 IB 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. 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. 23 A 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. 24 A 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;
  • the example embodiments of the present invention provide liquid ejection components typically used in inkjet printing systems.
  • inkjet printheads to emit liquids (other than inks) that need to be finely metered and deposited with high spatial precision.
  • 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.
  • cavity 115 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • a MEMS transducing material such as a piezoelectric material, or a shape memory alloy, or a thermal bimorph material
  • 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's modulus that is much less than the Young'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'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.
  • the Young'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'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.
  • the Young'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.
  • 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.
  • the widths wi see FIG. 1A
  • the widths W2 see FIG. 1A
  • the second ends 122 of the cantilevered beams 120 are all substantially equal to each other.
  • wi 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. IB), 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.
  • 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, IB and 2.
  • FIG. 4 shows an embodiment similar to FIG. 3, but for each of the four cantilevered beams 120, the width wi at the anchored end 121 is greater than the width w 2 at the cantilevered end 122.
  • 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.
  • 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 120a (one example of a MEMS transducing member) having larger first widths wi than second widths w 2 , there is a second group of cantilevered beams 120b (alternatingly arranged between elements of the first group) having first widths wi ' that are equal to second widths w 2 '.
  • group of cantilevered beams 120a one example of a MEMS transducing member
  • second group of cantilevered beams 120b alternatingly arranged between elements of the first group having first widths wi ' that are equal to second widths w 2 '.
  • the second group of cantilevered beams 120b are sized smaller than the first group of cantilevered beams 120a, such that the first widths wi' are smaller than first widths wi, 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 120b.
  • Such an arrangement is beneficial when the first group of cantilevered beams 120a are used for actuators and the second group of cantilevered beams 120b are used as sensors.
  • FIG. 6 shows an embodiment similar to FIG. 5 in which there are two groups of cantilevered beams 120c and 120d, with the elements of the two groups being alternatingly arranged.
  • the lengths L and L' of the cantilevered beams 120c and 120d respectively are less than 20% of the dimension D across cavity 115.
  • D is the diameter of the cavity 115.
  • the cantilevered beams 120 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.
  • the compliant membrane 130 across cavity 115 provides a degree of coupling between the MEMS transducing members.
  • 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. 1 A, 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.
  • 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.
  • 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
  • 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.
  • 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.
  • 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. 1 A, 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.
  • 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. IB.
  • 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. 1 IB 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.
  • 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.
  • 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.
  • 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.
  • the second through hole 116 can be the cavity of an adjacent MEMS composite transducer.
  • FIG. 12A The configuration shown in FIG. 12A can be used in a fluid ejector
  • 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 11 1 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).
  • 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.
  • the MEMS composite transducer is disposed along a plane, and at least a portion of the MEMS composite transducer is movable within the plane.
  • 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.
  • 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.
  • 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.
  • the MEMS transducing member for example, cantilevered beam 120
  • 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 US Patent No. 6,561,627.
  • the reference material 162 can include an insulator such as silicon oxide, or silicon oxide plus silicon nitride.
  • the 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.
  • 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 US Patent 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.
  • 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.
  • 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.
  • mass 118 extends below portion 133 of compliant membrane 130, so that it is located within the cavity 115.
  • 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.
  • 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.
  • layers such as the top and bottom electrode layers 166 and 168, as well as seed layer 167 are not required.
  • Drop forming pulses are provided by the stimulation controller
  • drop 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.
  • drop controller 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • the charge distribution induced on the catcher 435 makes up a portion of the deflection mechanism 425.
  • 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.
  • a single biased electrode in front of the upper grounded portion of the catcher is used and described in US 4,245,226.
  • a pair of additional electrodes are used and described in US 6,273,559
  • the deflection mechanism 425 also includes a second charge electrode 420A located on the opposite side of the jet array 405 from the (first) charge electrode 420.
  • Second charge electrode 420A 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 420A biased to the same potential as first charge electrode 420 produces a region between the charging electrodes 420 and 420A with a very uniform electric field.
  • the deflection mechanism 425 also includes a deflection electrode
  • FIGS. 27 A and 27B also show a graph illustrating the voltage or electrical potential on the charge electrode 420 and second charge electrode 420A at the respective times when a drop 400 breaks off.
  • the periodicity of the electrical potential on the charge electrode 420 and 420A is synchronized with the pulse stimulation signals provided to the drop generator 395 located at each orifice 135.
  • 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.
  • Liquid for example, ink
  • a liquid supply 335 under pressure.
  • 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.
  • 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.
  • 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.
  • pressure regulator 370 typically includes a liquid pump control system.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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. 28and 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).
  • 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 ⁇ 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).
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • catcher 435 is a type of catcher commonly referred to as a "Coanda" catcher.
  • 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.
  • 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.
  • a continuous liquid ejection system in step 600, 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 polymeric membrane is positioned in contact with the MEMS transducing member. A first portion of the compliant polymeric membrane covers the MEMS transducing member and a second portion of the compliant polymeric membrane is anchored to the substrate.
  • the compliant polymeric membrane includes an orifice.
  • 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 polymeric membrane of the orifice plate by a liquid supply.
  • step 605 is followed by step 610.
  • 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 polymeric membrane to be displaced relative to the liquid chamber. Step 610 is followed by step 615 and step 625.
  • step 620 an appropriately positioned catcher intercepts drops traveling along one of the first path and the second path.

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  • Micromachines (AREA)

Abstract

L'invention concerne un système d'éjection continue de liquide comprenant un substrat (110) et une plaque (315) à orifice fixée au substrat. Des parties du substrat définissent une chambre (310) à liquide. La plaque à orifice comprend un élément transducteur à MEMS. Une première portion de l'élément transducteur à MEMS est ancrée au substrat. Une deuxième partie de l'élément transducteur à MEMS s'étend par-dessus au moins une partie de la chambre à liquide et est libre de se déplacer par rapport à la chambre à liquide. Une membrane déformable (320) est positionnée en contact avec l'élément transducteur à MEMS. Une première partie de la membrane déformable recouvre l'élément transducteur à MEMS et une deuxième partie de la membrane déformable est ancrée au substrat. La membrane déformable comprend un orifice (135). Une alimentation en liquide amène un liquide à la chambre à liquide sous une pression suffisante pour éjecter un jet continu du liquide à travers l'orifice situé dans la membrane déformable de la plaque à orifice. L'élément transducteur à MEMS est actionné sélectivement pour provoquer un déplacement d'une partie de la membrane déformable par rapport à la chambre à liquide afin d'amener une goutte de liquide à se détacher du jet de liquide.
PCT/US2012/033733 2011-04-19 2012-04-16 Système d'éjection continue comprenant un transducteur à membrane déformable WO2012145260A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
CN201280030136.6A CN103619598A (zh) 2011-04-19 2012-04-16 包括柔性膜换能器的连续喷射系统
EP12719833.1A EP2699423A1 (fr) 2011-04-19 2012-04-16 Système d'éjection continue comprenant un transducteur à membrane déformable

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US13/089,521 US8398210B2 (en) 2011-04-19 2011-04-19 Continuous ejection system including compliant membrane transducer
US13/089,594 US8529021B2 (en) 2011-04-19 2011-04-19 Continuous liquid ejection using compliant membrane transducer
US13/089,594 2011-04-19
US13/089,521 2011-04-19

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WO2012145260A1 true WO2012145260A1 (fr) 2012-10-26

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CN114513729B (zh) * 2022-01-07 2023-07-07 华为技术有限公司 电子设备及声学换能器

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CN103619598A (zh) 2014-03-05

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