Fluid ejection device with reduced crosstalk - Patents.com

Abstract

To stabilize the drop size and velocity of fluid ejected from each fluid ejector and enable precise and accurate printing.SOLUTION: A fluid ejection apparatus includes a plurality of fluid ejectors. Each fluid ejector includes a pumping chamber, and an actuator configured to cause fluid to be ejected from the pumping chamber. The fluid ejection apparatus includes a feed channel fluidically connected to each pumping chamber, and at least one compliant structure formed in a surface of the feed channel. The at least one compliant structure has lower compliance than the surface of the feed channel.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates generally to fluid ejection devices. [Background technology]

[0002] In some fluid ejection devices, fluid droplets are ejected from one or more nozzles onto a medium. The nozzles are fluidly connected to a fluid path that includes a fluid pumping chamber. The fluid pumping chamber can be actuated by an actuator, which causes the ejection of the fluid droplets. The medium can be moved relative to the fluid ejection device. The ejection of the fluid droplets from a particular nozzle is timed as the medium moves, causing the fluid droplets to land at a desired location on the medium. The ejection of the fluid droplets in the same direction with uniform size and velocity allows for uniform deposition of the fluid droplets on the medium. Summary of the Invention [Means for solving the problem]

[0003] When an actuator of a fluid ejector is activated, pressure fluctuations can propagate from the pumping chamber into the connected inlet and outlet feed channels. This pressure fluctuation can propagate into other fluid ejectors connected to the same inlet or outlet feed channel. This fluid crosstalk can adversely affect print quality.

[0004] To mitigate the propagation of pressure fluctuations, compliant microstructures can be formed in one or more surfaces of the inlet feed channel, the outlet feed channel, or both. The presence of the compliant microstructures in the feed channel increases the compliance available at the surface of the feed channel, damping pressure fluctuations occurring in that feed channel. In some examples, the compliant microstructures include a recess formed in a bottom surface of the feed channel. A membrane covers the recess and deflects into the recess in response to an increase in pressure in the feed channel, thus damping pressure fluctuations. In some examples, the compliant microstructures include a nozzle-like structure formed in a bottom surface of the feed channel. As pressure in the feed channel increases, a meniscus at the outwardly facing opening of each nozzle-like structure can dampen pressure fluctuations. The presence of such compliant microstructures can thus reduce fluidic crosstalk between fluid ejectors connected to the same inlet or outlet feed channel, thus stabilizing the droplet size and velocity of fluid ejected from each fluid ejector, enabling precise and accurate printing.

[0005] In a general aspect, a fluid ejection device includes a plurality of fluid ejectors, each of which includes a pumping chamber and an actuator configured to eject fluid from the pumping chamber. The fluid ejection device includes a feed channel fluidly connected to each pumping chamber and at least one compliant structure formed in a surface of the feed channel, the at least one compliant structure having a lower compliance than the surface of the feed channel.

[0006] Implementations may include one or more of the following features.

[0007] At least one compliant structure comprises a plurality of recesses formed in a surface of the feed channel and a membrane disposed across the recesses. In some cases, the membrane seals the recesses. In some cases, a depth of each recess is less than a thickness of the surface of the feed channel. In some cases, the membrane is configured to deflect into the recesses in response to an increase in fluid pressure in the feed channel. In some cases, the recesses are formed in one or more of a bottom or top wall of the feed channel. In some cases, the recesses are formed in a side wall of the feed channel.

[0008] At least one compliant structure comprises one or more dummy nozzles formed in a surface of the feed channel. In some cases, each dummy nozzle includes a first opening on an interior surface of the surface and a second opening on an exterior surface of the surface. In some cases, a convex meniscus is formed at the second opening in response to an increase in fluid pressure in the feed channel. In some cases, each fluid ejector includes a nozzle formed in a nozzle layer, and the dummy nozzle is formed in the nozzle layer. In some cases, the dummy nozzle is substantially the same size as the nozzle.

[0009] Each fluid ejector includes a nozzle formed in a nozzle layer, which defines a surface of a feed channel.

[0010] Each fluid ejector includes an actuator and a nozzle, where actuation of one of the actuators causes fluid to be ejected from a corresponding nozzle. In some cases, actuation of one of the actuators causes a change in fluid pressure in the feed channel, and the at least one compliant structure is configured to at least partially damp the change in fluid pressure in the feed channel.

[0011] In a general aspect, the method includes forming a plurality of nozzles in a nozzle layer; forming at least one compliant structure in the nozzle layer, the at least one compliant structure having a lower compliance than the nozzle layer; and attaching the nozzle layer to a substrate comprising a plurality of fluid ejectors, each fluid ejector comprising a pumping chamber and an actuator configured to eject fluid from the pumping chamber.

[0012] Implementations may include one or more of the following features.

[0013] Forming at least one compliant structure in the nozzle layer includes forming a plurality of recesses in the nozzle layer and disposing a membrane over the recesses. In some cases, disposing the membrane over the recesses includes depositing a membrane layer over a top surface of the nozzle layer and removing a portion of the membrane layer over each nozzle.

[0014] The step of forming the plurality of nozzles includes forming the plurality of nozzles in a first layer, and the step of forming the at least one compliant structure includes forming the at least one compliant structure in a second layer and attaching the first layer to the second layer.

[0015] The step of forming at least one compliant structure in the nozzle layer includes forming at least one compliant structure in a first layer and attaching the first layer to a second layer having a plurality of nozzles formed therein, the first layer and the second layer together forming the nozzle layer.

[0016] Forming at least one compliant structure in the nozzle layer includes forming one or more dummy nozzles in the nozzle layer.

[0017] In a general aspect, a method includes actuating a fluid ejector in a fluid ejection device. Actuation of the fluid ejector causes a change in fluid pressure in a feed channel fluidly connected to the fluid ejector. The method includes deflecting a membrane into a recess formed in a surface of the feed channel in response to the change in fluid pressure in the feed channel.

[0018] Implementations may include one or more of the following features.

[0019] The step of deflecting the membrane into the recess includes the step of reverse deflecting the membrane.

[0020] The approaches described herein may have one or more of the following advantages: The presence of compliant microstructures, such as recesses or dummy nozzles, in the surface of a feed channel may mitigate fluidic crosstalk between fluid ejectors fluidly connected to that feed channel. For example, the compliant microstructures may increase the compliance available in the surface of the feed channel, thus allowing energy from pressure fluctuations caused by actuation of an actuator in a fluid ejector to be damped. As a result, the effect of pressure fluctuations on other fluid ejectors connected to that feed channel may be reduced. By reducing fluidic crosstalk between fluid ejectors in a printhead, the drop size and velocity of fluids ejected from the fluid ejectors may be stabilized, thus enabling precise and accurate printing.

[0021] The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages will become apparent from the description, drawings, and claims. [Brief description of the drawings]

[0022] [Figure 1] FIG. 1 is a cross-sectional view of a print head. [Diagram 2] FIG. 2 is a cross-sectional view of a portion of a printhead. [Diagram 3] FIG. 3 is a cross-sectional view of a fluid ejector. [Figure 4A] FIG. 4A is a cross-sectional view of a portion of the printhead taken along line BB in FIG. [Figure 4B] FIG. 4B is a cross-sectional view of a portion of the printhead taken along line CC in FIG. [Figure 5A] FIG. 5A is a top view of a feed channel with a recess. [Figure 5B] FIG. 5B is a side view of a feed channel with a recess. [Figure 6A] FIG. 6A is a schematic diagram of an approach for fabricating a fluid ejector having a recess. [Figure 6B] FIG. 6B is a schematic diagram of an approach for fabricating a fluid ejector having a recess. [Figure 6C] FIG. 6C is a schematic diagram of an approach for fabricating a fluid ejector having a recess. [Figure 6D] View DC is a schematic diagram of an approach for fabricating a fluid ejector having a recess. [Figure 6E] FIG. 6E is a schematic diagram of an approach for fabricating a fluid ejector having a recess. [Figure 6F] FIG. 6F is a schematic diagram of an approach for fabricating a fluid ejector having a recess. [Figure 7] FIG. 7 is a flow diagram. [Figure 8A] FIG. 8A is a schematic diagram of an approach for fabricating a fluid ejector having a recess. [Figure 8B] FIG. 8B is a schematic diagram of an approach for fabricating a fluid ejector having a recess. [Figure 8C] FIG. 8C is a schematic diagram of an approach for fabricating a fluid ejector having a recess. [Figure 8D] FIG. 8D is a schematic diagram of an approach for fabricating a fluid ejector having a recess. [Figure 8E] FIG. 8E is a schematic diagram of an approach for fabricating a fluid ejector having a recess. [Figure 8F] FIG. 8F is a schematic diagram of an approach for fabricating a fluid ejector having a recess. [Figure 9] FIG. 9 is a flow diagram. [Figure 10] FIG. 10 is a cross-sectional view of a fluid ejector having sidewall compliant microstructures. [Figure 11] FIG. 11 is a side view of a feed channel with a dummy nozzle. [Figure 12] FIG. 12 is a schematic diagram of an approach for fabricating a fluid ejector with a dummy nozzle.

[0023] Like reference numbers and designations in the various drawings indicate like elements. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] 1, a print head 100 can be used to eject droplets of a fluid, such as ink, a biological liquid, a polymer, a liquid for forming electronic components, or other types of fluids onto a surface. The print head 100 includes a casing 410 with an interior volume that is divided into a fluid supply chamber 432 and a fluid return chamber 436, for example, by an upper divider 530 and a lower divider 440.

[0025] The bottom of the fluid supply chamber 432 and the fluid return chamber 436 are defined by a top surface of the interposer assembly. The interposer assembly can be attached to the lower printhead casing 410, such as by bonding, friction, or another attachment mechanism. The interposer assembly can include an upper interposer 420 and a lower interposer 430, which is positioned between the upper interposer 420 and the substrate 110.

[0026] The upper interposer 420 includes a fluid supply inlet 422 and a fluid return outlet 428. For example, the fluid supply inlet 422 and the fluid return outlet 428 can be formed as openings in the upper interposer 420. A flow path 474 is formed in the upper interposer 420, the lower interposer 430, and the substrate 110. Fluid can flow along the flow path 474 from the supply chamber 432 into the fluid supply inlet 422 and to one or more fluid ejection devices (described in more detail below) for ejection from the print head 100. Fluid can also flow along the flow path 474 from the one or more fluid ejection devices into the fluid return outlet 428 and into the return chamber 436. In FIG. 1, the single flow path 474 is shown as a straight passage for illustrative purposes. However, the print head 100 can include multiple flow paths 474, and the flow path 474 is not necessarily straight.

[0027] 2 and 3, the substrate 110 can be a monolithic semiconductor body, such as a silicon substrate. A passage through the substrate 110 defines a flow path for a fluid through the substrate 110. In particular, the substrate inlet 12 receives fluid from a supply chamber 432 and extends through a membrane 66 (discussed in more detail below) to supply the fluid to one or more inlet feed channels 14. Each inlet feed channel 14 supplies the fluid through a corresponding inlet passage (not shown) to a number of fluid ejectors 150. For convenience, only one fluid ejector 150 is shown in FIGS. 2 and 3. Each fluid ejector includes a nozzle 22 formed in a nozzle layer 11 disposed on a bottom surface of the substrate 110. In some embodiments, the nozzle layer 11 is an integral part of the substrate 110. In some embodiments, the nozzle layer 11 is a layer that is deposited on the surface of the substrate 110. Fluid can be selectively ejected from nozzles 22 of one or more of the fluid ejectors 150 and printed onto a surface.

[0028] Fluid flows through each fluid ejector 150 along an ejector flow path 475. The ejector flow path 475 may include a pumping chamber inlet passage 17, a pumping chamber 18, a descender 20, and an outlet passage 26. The pumping chamber inlet passage 17 fluidly connects the pumping chamber 18 to the inlet feed channel 14 and may include, for example, an ascender 16 and a pumping chamber inlet 15. The descender 20 is fluidly connected to a corresponding nozzle 22. The outlet passage 26 connects the descender 20 to an outlet feed channel 28, which fluidly connects with the return chamber 436 through a substrate outlet (not shown).

[0029] 2 and 3, passages such as the substrate inlet 12, the inlet feed channel 14, and the outlet feed channel 28 are shown in a common plane. In some embodiments (e.g., the embodiment of FIGS. 3A and 3B), one or more of the substrate inlet 12, the inlet feed channel 14, and the outlet feed channel 28 are not in a common plane with the other passages.

[0030] 4A and 4B, a substrate 110 includes a plurality of inlet feed channels 14 formed therein and extending parallel to one another. Each inlet feed channel 14 is in fluid communication with at least one substrate inlet 12 extending perpendicular to the inlet feed channel 14. The substrate 110 also includes a plurality of outlet feed channels 28 formed therein and extending parallel to one another. Each outlet feed channel 28 is in fluid communication with at least one substrate outlet (not shown) extending perpendicular to the outlet feed channel 28. In some embodiments, the inlet feed channels 14 and the outlet feed channels 28 are arranged in alternating rows.

[0031] The substrate includes a plurality of fluid ejectors 150. Fluid flows through each fluid ejector 150 along a corresponding ejector flow path 475, which includes an ascender 16, a pumping chamber inlet 15, a pumping chamber 18, and a descender 20. Each ascender 16 is fluidly connected to one of the inlet feed channels 14. Each ascender 16 is also fluidly connected to a corresponding pumping chamber 18 through a pumping chamber inlet 15. The pumping chamber 18 is fluidly connected to a corresponding descender 20, which leads to an associated nozzle 22. Each descender 20 is also connected to one of the outlet feed channels 28 through a corresponding outlet passage 26. For example, a cross-sectional view of the fluid ejector of FIG. 3 is taken along line 2-2 in FIG. 4A.

[0032] The particular flow path configurations described herein are examples of flow path configurations. The approaches described herein can also be used in other flow path configurations.

[0033] In some embodiments, the print head 100 includes a plurality of nozzles 22 arranged in parallel rows 23. All of the nozzles 22 in a given row 23 may be fluidly connected to the same inlet feed channel 14 and the same outlet feed channel 28. That is, for example, all of the ascenders 16 in a given row may be connected to the same inlet feed channel 14 and all of the descenders in a given row may be connected to the same outlet feed channel 28.

[0034] In some embodiments, the nozzles 22 in adjacent columns can all be fluidly connected to the same inlet feed channel 14 or the same outlet feed channel 28, but not both. For example, in the embodiment of FIG. 4A, each nozzle 22 in column 23a is fluidly connected to inlet feed channel 14a and outlet feed channel 28a. Nozzles 22 in adjacent column 23b are also connected to inlet feed channel 14a, but not to outlet feed channel 28b. In some embodiments, columns of nozzles 22 can be connected to the same inlet feed channel 14 or the same outlet feed channel 28 in an alternating pattern. Further details regarding the print head 100 can be found in U.S. Pat. No. 7,566,118, the contents of which are incorporated herein by reference in their entirety.

[0035] 2, each fluid ejector 150 includes a corresponding actuator 30, such as a piezoelectric transducer or a resistive heater. The pumping chamber 18 of each fluid ejector 150 is in close proximity to a corresponding actuator 30. Each actuator 30 can be selectively actuated to pressurize the corresponding pumping chamber 18 and thus eject fluid from a nozzle 22 connected to the pressurized pumping chamber.

[0036] In some embodiments, the actuator 30 can include a piezoelectric layer 31, such as a layer of lead zirconate titanate (PZT). The piezoelectric layer 31 can have a thickness of about 50 μm or less, such as about 1 μm to about 25 μm, such as about 2 μm to about 5 μm. In the embodiment of FIG. 2, the piezoelectric layer 31 is continuous. In some embodiments, the piezoelectric layer 31 can be made discontinuous during processing, such as by an etching or sawing step. The piezoelectric layer 31 is sandwiched between a drive electrode 64 and a ground electrode 65. The drive electrode 64 and the ground electrode 65 can be metal, such as copper, gold, tungsten, indium tin oxide (ITO), titanium, platinum, or a combination of metals. The thickness of the drive electrode 64 and the ground electrode 65 can be, for example, about 2 μm or less, such as about 0.5 μm.

[0037] A membrane 66 is disposed between the actuator 30 and the pumping chamber 18 and isolates the ground electrode 65 from the fluid in the pumping chamber 18. In some embodiments, the membrane 66 is a separate layer. In some embodiments, the membrane is integral with the substrate 110. In some embodiments, the actuator 30 does not include the membrane 66 and the ground electrode 65 is formed on the back side of the piezoelectric layer 31 such that the piezoelectric layer 31 is directly exposed to the fluid in the pumping chamber 18.

[0038] To operate the piezoelectric actuator 30, an electrical voltage can be applied between the drive electrode 64 and the ground electrode 65, applying a voltage to the piezoelectric layer 31. The applied voltage deflects the piezoelectric layer 31, which in turn deflects the membrane 66. The deflection of the membrane 66 causes a change in volume in the pumping chamber 18, producing a pressure pulse (also referred to as a firing pulse) in the pumping chamber 18. The pressure pulse propagates through the descender 20 to a corresponding nozzle 22, thus causing a droplet of fluid to be ejected from the nozzle 22.

[0039] The membrane 66 can be formed from silicon (e.g., single crystal silicon), a single layer of another semiconductor material, an oxide such as aluminum oxide (AlO2) or zirconium oxide (ZrO2), one or more layers of glass, aluminum nitride, silicon carbide, other ceramics or metals, silicon on an insulator, or other materials. For example, the membrane 66 can be formed from an inert material that has compliance such that actuation of the actuator 30 causes sufficient bending of the membrane 66 to eject a droplet of fluid. In some embodiments, the membrane 66 can be affixed to the actuator 30 using an adhesive layer 67. In some embodiments, two or more of the substrate 110, the nozzle layer 11, and the membrane 66 can be formed as a unitary body.

[0040] In some cases, when the actuator 30 of one of the fluid ejectors 150 is actuated, pressure fluctuations may propagate through the ascender 16 of the fluid ejector 150 into the inlet feed channel 14. Similarly, energy from the pressure fluctuations may also propagate through the descender 20 of the fluid ejector 150 into the outlet feed channel 28. In some cases, the present application generally refers to the inlet feed channel 14 and the outlet feed channel 28 as feed channels 14, 28. Pressure fluctuations may thus occur within one or more of the feed channels 14, 28 that are connected to the actuated fluid ejector 150. In some cases, these pressure fluctuations may propagate into the ejector flow paths 475 of other fluid ejectors 150 that are connected to the same feed channels 14, 28. These pressure fluctuations may adversely affect the drop volume and / or drop velocity of droplets ejected from those fluid ejectors 150, degrading print quality. For example, variations in drop volume can vary the amount of fluid ejected, and variations in drop velocity can vary where the ejected drops are deposited on the printing surface. The induction of pressure variations within a fluid ejector is referred to as fluid crosstalk.

[0041] In some embodiments, fluidic crosstalk may be caused by the slow dissipation of pressure fluctuations in the feed channels 14, 28. In some embodiments, fluidic crosstalk may be caused by standing waves generated in the feed channels 14, 28. For example, when the actuator 30 of one of the fluid ejectors 150 is actuated, the pressure fluctuations propagating in the feed channels 14, 28 may be generated in standing waves. When fluid ejection occurs at a frequency that enhances the standing waves, the standing waves in the feed channels 14, 28 may propagate pressure oscillations into the ejector flow paths 475 of other fluid ejectors 150 connected to the same feed channel 14, 28, causing fluidic crosstalk between those fluid ejectors 150.

[0042] Fluidic crosstalk can also result from sudden changes in the fluid flowing through the feed channels 14, 28. In general, when a fluid moving through a flow channel is suddenly forced to stop or redirect, a pressure wave can propagate through the flow channel (also referred to as a "water hammer" effect). For example, when one or more fluid ejectors 150 connected to the same feed channel 14, 28 are suddenly turned off, the water hammer effect causes a pressure wave to propagate into the flow channel 14, 28. The pressure wave can further propagate into the ejector flow paths 475 of other fluid ejectors 150 connected to the same feed channel 14, 28, causing fluidic crosstalk between those fluid ejectors 150.

[0043] Fluidic crosstalk can be reduced by providing greater compliance in the fluid ejectors to dampen pressure fluctuations. By increasing the compliance available in the fluid ejectors, the energy from pressure fluctuations generated in one of the fluid ejectors can be dampened, thus reducing the effect of the pressure fluctuations on neighboring fluid ejectors.

[0044] Compliance within the fluid ejector and its associated fluid flow path is available to the fluid, the meniscus at the nozzle, and the surfaces of the fluid flow path (e.g., the inlet feed channel 14, the pumping chamber inlet passage 17, the descender 20, the outlet passage 26, the outlet feed channel 28, and other fluid flow paths).

[0045] The compliance of the fluid in the feed channel is given by:

[0046]

number

[0047] where V is the volume of the fluid in the feed channel and B is the bulk modulus of the fluid.

[0048] The compliance of a single meniscus is given by:

[0049]

number

[0050] where r is the radius of the meniscus and σ is the surface tension.

[0051] The compliance of a rectangular surface (such as the surface of an inlet or outlet feed channel) is given (for fixed end conditions) by:

[0052]

number

[0053] In the formula, l, w, and t w are the length, width, and thickness of the surface, respectively. Each surface of the inlet and outlet feed channels has some degree of compliance. In some fluid ejectors, the most compliant surface of the feed channel is the bottom surface formed by the silicon nozzle layer 11.

[0054] In one specific embodiment, the printhead has a feed channel (e.g., inlet feed channel 14 or outlet feed channel 28) that feeds 16 fluid ejectors (so there are 16 menisci associated with the feed channel). The feed channel has a width of 0.39 mm, a depth of 0.27 mm, and a length of 6 mm. The thickness of the silicon nozzle layer 11 is 30 μm, and the elastic modulus of the nozzle layer is 186E9 Pa. The radius of each meniscus is 7 μm. A typical bulk modulus for water-based inks is about B=2E9 Pa, and a typical surface tension is about 0.035 N / m.

[0055] For this example, the compliance of the fluid in the feed channel, the 16 meniscus, and the nozzle layer in the feed channel are given in Table 1. Notably, the nozzle layer in the feed channel has the lowest compliance.

[0056] [Table 1]

[0057] Table 1. Compliance values ​​of the fluid in the feed channel, the meniscus of the 16 nozzles fed by the feed channel, and the nozzle layer of the feed channel.

[0058] Increasing compliance within a fluid ejector 150 and its associated fluid flow path can help mitigate fluidic crosstalk between fluid ejectors 150. By increasing the available compliance, the propagation of pressure fluctuations from a particular fluid ejector 150 to neighboring fluid ejectors 150 can be attenuated within the fluid ejector 150 or the inlet and / or outlet feed channels 14, 28 to which the fluid ejector 150 is connected, thus reducing the effect of that pressure fluctuation on other fluid ejectors 150. For example, the compliance of a feed channel 14, 28 can be increased to mitigate fluidic crosstalk between fluid ejectors 150 connected to that feed channel 14, 28.

[0059] 3, compliance can be added to the inlet feed channel 14, the outlet feed channel 28, or both by forming compliant microstructures 50 on one or more surfaces of the inlet feed channel 14 and / or the outlet feed channel 28. For example, in the embodiment of FIG. 3, the compliant microstructures 50 are formed in the bottom surface 52 of the inlet feed channel 14 and the bottom surface 54 of the outlet feed channel. In this embodiment, the bottom surfaces 52, 54 are formed by the nozzle layer 11. The additional compliance provided by the compliant microstructures 50 in the feed channels 14, 28 attenuates energy from pressure fluctuations in a particular fluid ejector 150 connected to that feed channel 14, 28. As a result, the effect of that pressure fluctuation on other fluid ejectors 150 connected to that same feed channel 14, 28 can be reduced. 5A and 5B, in some embodiments, the compliant microstructure 50 formed in the nozzle layer 11 of the inlet feed channel 14 and / or the outlet feed channel 28 can be a recess 500 covered by a thin film 502. The membrane 502 is disposed across the recess 500 such that an inner surface 504 of the nozzle layer 11 facing into the feed channel 14, 28 is substantially flat. In some cases, for example, when a vacuum is present in the recess 500, the membrane 502 can be slightly biased into the recess 500. In some examples, the recess 500 can be formed in the nozzle layer 11, also referred to as the bottom wall of the inlet or outlet feed channel 14, 28. In some examples, the recess 500 can be formed in the top wall of the inlet or outlet feed channel, which is the wall opposite the bottom wall. In some embodiments, the recess 500 can be formed in one or more sidewalls of the inlet or outlet feed channel 14, 28, that is the wall that intersects the top and bottom walls.

[0060] When pressure fluctuations propagate into the feed channel 14, 28, the membrane 502 can deflect into the recess, dampening the pressure fluctuations and mitigating fluidic crosstalk between neighboring fluid ejectors 150 connected to that feed channel 14, 28. The deflection of the membrane 502 is reversible such that when the fluid pressure in the feed channel 14, 28 is reduced, the membrane 502 returns to its original configuration.

[0061] The recesses 500 can have a lateral dimension (e.g., radius) of about 50 μm to about 150 μm, e.g., about 100 μm. For example, the lateral dimension of the recesses 500 can be about 10% to about 75% of the width of the feed channel surface, e.g., about 50% of the width of the feed channel surface. The recesses 500 can have a depth of about 5 μm to about 15 μm, e.g., about 6-10 μm. The recesses 500 can have a density of about 10 recesses / mm. 2 ~About 50 depressions / mm 2 , for example, about 20 depressions / mm 2 5A and 5B, the recesses 500 are circular. In some embodiments, the recesses 500 can be other shapes, such as oval, elliptical, or other shapes. For example, the recesses 500 can be shaped such that there are no sharp angles where mechanical stresses can concentrate. The recesses 500 can be positioned in an ordered array, e.g., rows and columns, although this is not required. For example, the recesses 500 can be randomly distributed.

[0062] In some embodiments, the membrane 502 can be formed from silicon. In some embodiments, the membrane 502 can be formed from an oxide, such as SiO2. In some embodiments, the membrane 502 can be formed from a metal, such as a sputtered metal layer. In general, the membrane 502 is thin enough to be able to deflect in response to pressure fluctuations in the feed channel 14, 28. In addition, the membrane 502 is thick enough to be durable. The overall elastic modulus of the membrane 502 should be sufficient so that the membrane will not deflect to the bottom 506 of the recess 500 under expected pressure fluctuations in operation, otherwise the membrane 502 may break or bond to the bottom 506 of the recess 500. For example, the membrane can have a thickness of about 0.5 μm to about 5 μm, such as about 1 μm, about 2 μm, or about 3 μm.

[0063] The presence of multiple recesses 500 in each feed channel 14, 28 can help ensure that even if one or more membranes 502 fail (e.g., by breaking or bonding to the bottom 506 of the recess 500), the compliance of the nozzle layer 11 in the feed channel 14, 28 can be reduced.

[0064] The membrane 502 can seal the recess 500 against fluids such as liquids (e.g., ink) and gases (e.g., air). In some embodiments, the recess 500 is vented during processing and then sealed such that a desired pressure is achieved within the recess, e.g., atmospheric pressure (atm), ½ atm, or another pressure. In some embodiments, the recess 500 is not vented such that a vacuum exists within the recess. The presence of a vacuum within the recess 500 can increase the stress on the membrane 502 and can reduce the additional compliance provided by the recess 500.

[0065] The compliance of the nozzle layer 11 in the feed channel, including the recess at 48, can be calculated by:

[0066]

number

[0067] where N is the number of recesses and a is the radius of each recess. D is given by:

[0068]

number

[0069] where E is the elastic modulus of the membrane, and t m is the thickness of the membrane and ' is the Poisson's ratio of the membrane.

[0070] The central deflection of the membrane can be calculated by:

[0071]

number

[0072] where q is the design pressure load of the membrane. This center deflection formula applies when the deflection is small, e.g., for deflections up to about 5% of the membrane thickness. In some embodiments, larger deflections may deviate from this formula. For example, the 2 μm thick exemplary membrane 502 deflects 3.2 μm and is 3.5 times stiffer than predicted by this formula.

[0073] The tensile stress in the membrane 502 can be calculated by:

[0074]

number

[0075] In one specific embodiment, 48 recesses of 100 μm radius are formed in the nozzle layer 11 in the feed channels 14, 28 with the dimensions and elastic modulus given above. The membrane 502 covering the recesses is formed from SiO2 thermal oxide and has a thickness of 2.0 μm, an elastic modulus of 75E9 Pa, and a Poisson's ratio of 0.17. The recesses 500 are not vented. The design pressure load q is set to 150000 Pa, taking into account 1 atm for the vacuum in the recesses and 0.5 atm for the purge pressure of the feed channels.

[0076] For this example, the compliance of nozzle layer 11, the center deflection of membrane 502, and the tensile stress in membrane 502 are given in the first column of Table 2. Notably, the presence of 48 recesses increased the compliance of the nozzle layer by approximately 9 times compared to a nozzle layer without recesses (discussed above and in Table 1).

[0077] [Table 2]

[0078] Table 2. Compliance of the nozzle layer in the feed channel, central deflection of the membrane, and tensile stress in the membrane.

[0079] In some cases, the film 502 is deposited under compressive stress, which increases the center deflection y beyond that given in Table 2. ccan be increased. For example, the central deflection of membrane 502 can exceed half the membrane thickness. In these circumstances, the stiffness of the membrane is increased and the stress for a given load is less (as explained in more detail in Section 11.11 of Roark's Formulas for Stress and Strain (7th Edition), the contents of which are incorporated herein by reference in their entirety). For example, in the example given above, the central deflection of the membrane is 2.3 times the membrane thickness. Thus, the stiffness of the membrane is increased by a factor of 2.5. The compliance, central deflection, and tensile stress taking into account this increased stiffness are given in the second column of Table 2. The compliance of the nozzle layer with the recess is increased by an additional factor of 3.5 compared to the nozzle layer without the recess.

[0080] These calculations indicate that the presence of the recesses 500 in the nozzle layer 11 can significantly increase the compliance of the nozzle layer 11. A nozzle layer 11 having such recesses 500 can therefore more effectively dampen pressure fluctuations in the feed channels 14, 28 than a flat nozzle layer 11, mitigating fluid crosstalk between fluid ejectors 150 connected to the feed channels 14, 28.

[0081] 6A-6F illustrate one approach for fabricating a fluid ejector 150 having a recess 500 formed in the nozzle layer 11. With reference to FIGS. 6A and 7, a nozzle wafer 60 (e.g., a silicon wafer) includes the nozzle layer 11 (e.g., a silicon nozzle layer), an etch stop layer 62 (e.g., an oxide or nitride etch stop layer such as SiO2 or Si3N4), and a handle layer 64 (e.g., a silicon handle layer). In some embodiments, the nozzle wafer 60 does not include the etch stop layer 62. In some embodiments, the nozzle wafer 80 is a silicon on insulator (SOI) wafer, where the insulator layer of the SOI wafer acts as the etch stop layer 84.

[0082] An opening, which will provide the nozzle 22, is formed (700) through the nozzle layer 11 using standard microfabrication techniques, including, for example, lithography and etching.

[0083] A recess 500 extending partially, but not entirely, through the nozzle layer 11 is also formed (702) using standard microfabrication techniques, including, for example, lithography and etching. For example, a first layer of resist can be deposited on the unpatterned nozzle layer 11 and lithographically patterned. The nozzle layer 11 can be etched, for example, using deep reactive ion etching (DRIE), to form the nozzle 22. The first layer of resist can be stripped and a second layer of resist can then be deposited on the nozzle layer 11 and lithographically patterned. The nozzle layer 11 can be etched according to the patterned resist, for example, using wet or dry etching, to form the recess 500.

[0084] 6B and 7, a second wafer 68 having a handle layer 69 and a membrane layer 70 that will provide the membrane 502 is bonded to the nozzle wafer 60. In particular, the membrane layer 70 is bonded (704) to the nozzle layer 11 of the nozzle wafer 60 using, for example, thermal bonding or another wafer bonding technique. The layer membrane 70 can be an oxide (e.g., SiO2 thermal oxide).

[0085] 6C and 7, the handle layer 69 is removed, for example, by grinding and polishing, wet etching, plasma etching, or another removal process, leaving behind the membrane layer 70 (706). With reference to Figures 6D and 7, the membrane layer 70 is masked and etched, for example, using standard microfabrication techniques including lithography and etching, to expose the nozzle 22 (708). The remaining portion of the membrane layer 70 forms the membrane 502 spanning the recess 500.

[0086] The patterned nozzle wafer 60 having the nozzles 22 and recesses 500 formed therein can be further processed, for example, as described in U.S. Patent No. 7,566,118, the contents of which are incorporated herein by reference in their entirety, to form the fluid ejectors 150 of the print head 100. With reference to Figures 6E and 7, in some embodiments, a top surface 74 of the patterned nozzle wafer 60 can be bonded (710) to a flow path wafer 76 having flow paths, such as descenders 20 and other flow paths (not shown), actuators (not shown), and other elements formed therein. For example, the top surface 74 of the nozzle wafer 60 can be bonded to the flow path wafer 76 using low temperature bonding, such as bonding with an epoxy (e.g., benzocyclobutene (BCB)) or using low temperature plasma activated bonding.

[0087] 6F and 7, the handle layer 64 can then be removed (712), for example, by grinding and polishing, wet etching, plasma etching, or another removal process. The etch stop layer 62, if present, is either removed (as shown in FIG. 6F) or masked and etched to expose the nozzle (714), using standard microfabrication techniques including, for example, lithography and etching.

[0088] In some embodiments, a thick nozzle wafer 60 can be used (e.g., 30 μm, 50 μm, or 100 μm thick). The use of a thick nozzle wafer minimizes the risk that the nozzle fabrication process will thin the nozzle wafer to the point where it becomes weak.

[0089] 8A-8D show another approach for fabricating a fluid ejector 150 having a recess 500 in the nozzle layer. With reference to FIGS. 8A and 9, a nozzle wafer 80 (e.g., a silicon wafer) includes a nozzle sub-layer 82 (e.g., a silicon nozzle sub-layer), an etch stop layer 84 (e.g., an oxide or nitride etch stop layer such as SiO2 or Si3N4), and a handle layer 86 (e.g., a silicon handle layer). In some embodiments, the nozzle wafer 80 does not include the etch stop layer 84. In some embodiments, the nozzle wafer 80 is a silicon on insulator (SOI) wafer, where the insulator layer of the SOI wafer acts as the etch stop layer 84.

[0090] An opening, which will provide the nozzle 22, is formed (900) through the nozzle sub-layer 82 using standard micro-fabrication techniques, including, for example, lithography and etching.

[0091] 8B and 9, the second wafer 86 includes a top layer 88, an etch stop layer 90 (e.g., an oxide or nitride etch stop layer such as SiO2 or Si3N4), and a handle layer of silicon 92. The top layer 88 can be formed of the same material (e.g., silicon) as the nozzle sub-layer 82. A recess 500 is etched (902), for example, through the top layer 88 of the SOI wafer 86 using standard microfabrication techniques including, for example, lithography and etching. In some embodiments, the second wafer 86 is an SOI wafer, and an insulator layer of the SOI wafer acts as the etch stop layer 90.

[0092] 8C and 9, the SOI wafer 86 is bonded (904) to the nozzle wafer 80, for example using thermal bonding or another wafer bonding technique, such that the top layer 88 of the SOI wafer 86 contacts the nozzle sub-layer 82 of the nozzle wafer 80. The recess 500 and the nozzle 22 are aligned, for example by utilizing a bonding alignment target (not shown) that is fabricated on the SOI wafer 86 and the nozzle wafer 80. For example, the alignment target may include an alignment indicator, such as a vernier, to indicate the amount of misalignment between the SOI wafer 86 and the nozzle wafer 80. In some embodiments, the SOI wafer 86 and the nozzle wafer 80 are aligned with an alignment tool that utilizes a camera, such as an infrared camera, to view the alignment target through the silicon wafer.

[0093] 8D and 9, the handle layer 92 of the SOI wafer 86 is removed (906), for example, by grinding and polishing, wet etching, plasma etching, or another removal process. With reference to Figures 8E and 9, the insulator layer 90 and top layer 88 are masked and etched (908) using standard microfabrication techniques, including, for example, lithography and etching, to expose the nozzle 22. The remaining insulator layer 88 forms a membrane 502 over the recess 500.

[0094] 8A-8E, the nozzle sub-layer 82 and top layer 88 together form the nozzle layer 11. The patterned nozzle wafer 80 can be further processed (910) to form printhead fluid ejectors 150, for example, as shown in Figures 6E and 6F and described in U.S. Patent No. 7,566,118, the contents of which are incorporated herein by reference in their entirety.

[0095] 8F, in some embodiments, the recess 500 can be vented such that the air within the recess is at atmospheric pressure. To fabricate a vented recess, a straight bore vent 95 is etched into the nozzle sub-layer 82 of the nozzle wafer 80 prior to bonding of the nozzle wafer 80 and the SOI wafer 86. The vent 95 is etched through the thickness of the nozzle sub-layer 82 down to the etch stop layer 84. The straight bore vent 95 is positioned such that when the nozzle wafer 80 is bonded with the SOI wafer 86, the vent 95 will be aligned with the recess 500. When the nozzle 22 is opened by removal of the handle layer 86 and the etch stop layer 84, the vent 95 will be open to the atmosphere, thus venting the interior space of the recess 500.

[0096] 10, in some embodiments, compliant microstructures can be added to the sidewalls 172, 174 of the inlet feed channel 14 and / or the outlet feed channel 28. For example, one or more recessed slots 170 can be formed adjacent one or both of the sidewalls 172, 174, leaving a sidewall membrane 176 between the recessed slot 170 and the interior of the feed channel 28. The sidewall membrane 176 can deflect into the recessed slot 170 in response to pressure fluctuations to attenuate pressure within the feed channel 14, 28. In some embodiments, the recessed slot 170 can be formed by DRIE vertical etching of the substrate 110 prior to bonding of the nozzle layer 11 to the substrate 110. In some embodiments, the recessed slot 170 can be formed using anisotropic or DRIE etching so that it is outwardly tapered, with the etching stopped by an etch stop layer, such as thermal oxide, grown on the sidewalls 172, 174.

[0097] 11, in some embodiments, the compliant microstructures 50 (FIG. 3) formed in the nozzle layer 11 of the inlet feed channel 14 and / or the outlet feed channel 28 can be nozzle-like structures 120, also referred to herein as dummy nozzles 120. (For clarity, the nozzles 22 of the fluid ejector 150 are also referred to as firing nozzles.) The dummy nozzles 120 are located in the feed channels 14, 28 and are not directly connected to or associated with any individual fluid ejector 150 and do not have corresponding actuators. The fluid pressure in the feed channels 14, 28 is generally not high enough to eject fluid from the dummy nozzles 120 during normal operation. For example, the fluid ejector 150 can operate at an ejection pressure of several atmospheres (e.g., about 1-10 atm), and the threshold pressure for ejection can be about half of the operating pressure.

[0098] The dummy nozzles 120 extend through the entire thickness of the nozzle layer 11 and provide a free surface that increases the compliance of the nozzle layer 11. Each dummy nozzle 120 includes an inwardly facing opening 122 on an inner surface 124 of the nozzle layer 11 and an outwardly facing opening 126 on an outer surface 128 (e.g., the surface facing towards the printing surface) of the nozzle layer 11. A meniscus 130 of fluid is formed at the outwardly facing opening 126 of each dummy nozzle 120 (shown in FIG. 11 for only one dummy nozzle 120). In some embodiments, the feed channels 14, 28 are negatively pressurized such that in the absence of pressure fluctuations, the meniscus 130 is drawn inwardly from the opening 126 (e.g., a concave meniscus). When pressure fluctuations propagate into the feed channel 14, 28, the meniscus 130 bulges (eg, a convex meniscus), dampening the pressure fluctuations and mitigating fluidic crosstalk between neighboring fluid ejectors 150 connected to that feed channel 14, 28.

[0099] In some embodiments, the dummy nozzle 120 is similar in size and / or shape to the firing nozzle 22. For example, the dummy nozzle 120 can be a generally cylindrical passage of constant diameter, with the inwardly facing opening 122 and the outwardly facing opening 126 having the same dimensions. The dummy nozzle 120 can also be a tapered cone-shaped passage extending from the larger inwardly facing opening 122 to the smaller outwardly facing opening 126. The dummy nozzle 120 can also include a quadratic curve-shaped passage extending from the larger inwardly facing opening 122 to the smaller outwardly facing opening 126. The dummy nozzle 120 can also include multiple cylindrical regions of gradually smaller diameters toward the outwardly facing opening 126.

[0100] When the dummy nozzle 120 is similar in size to the firing nozzle 22, the bubble pressures of the dummy nozzle 120 and the firing nozzle 22 are also similar. However, because the fluid pressure is generally lower in the feed channels 14, 28 than in the fluid ejector 150, fluid can be ejected from the firing nozzle 22 without accidental ejection through the dummy nozzle 120. In some embodiments, the dummy nozzle 120 can have a different size than the firing nozzle 22.

[0101] In some embodiments, the ratio of the thickness of the dummy nozzle 120 (e.g., the thickness of the nozzle layer 11) to the diameter of the outwardly facing opening 128 can be about 0.5 or greater, such as about 1 to 4, or about 1 to 2. For example, the radius of the outwardly facing opening 128 can be about 5 μm to about 80 μm, such as about 10 μm to about 50 μm. With respect to the tapered shape, the cone angle of the cone-shaped path of the dummy nozzle 120 can be, for example, about 5° to about 45°. In general, the dummy nozzle 120 is small enough so that large contaminant particles that can clog the firing nozzle 22 cannot enter the feed channels 14, 28 through the dummy nozzle 120.

[0102] In some embodiments, the print head 100 can be purged with high fluid pressure, for example to clear the fluid flow paths. The high fluid pressure during purging can cause fluid to be ejected from the dummy nozzles 120. To reduce fluid loss through the dummy nozzles 120 during such purging, a small number of dummy nozzles 120 can be formed in each feed channel 14, 28. For example, between 1 and 20 dummy nozzles 120 can be formed in each feed channel 14, 28, for example, about 1, 2, or 4 dummy nozzles per firing nozzle. In some embodiments, the dummy nozzles 120 can be capped during purging such that little or no fluid is lost through the dummy nozzles 120.

[0103] 12 illustrates an exemplary approach for fabricating a fluid ejector 150 having a dummy nozzle 120 formed in a nozzle layer 11. The nozzle wafer 140 includes the nozzle layer 11, an etch stop layer 142 (e.g., an oxide or nitride etch stop layer such as SiO2 or Si3N4), and a handle layer 124 (e.g., a silicon handle layer). In some embodiments, the nozzle wafer 120 does not include the etch stop layer 122.

[0104] The firing nozzles and dummy nozzles 120 are formed through nozzle layer 11 using standard microfabrication techniques, including, for example, lithography and etching. In some implementations, the firing nozzles 22 and the dummy nozzles 120 are formed in nozzle layer 11 at the same time, for example, using the same etching step.

[0105] After formation of firing nozzle 22 and dummy nozzle 120, processing may proceed substantially as shown and described with respect to FIGS. 6B-6F, except that dummy nozzle 120 replaces recess 500.

[0106] Because the dummy nozzles 120 are formed during the processing steps that would occur to form the firing nozzles 22, there is little cost impact associated with forming the dummy nozzles 120. In the embodiment shown, the firing nozzles 22 and the dummy nozzles 120 are the same size. In some embodiments, the firing nozzles 22 and the dummy nozzles 120 can have different sizes.

[0107] Although specific embodiments have been described, other embodiments are within the scope of the following claims.

[0108] Many variations and modifications may be made to the above-described embodiments of the present disclosure without departing substantially from the spirit and various principles of the present disclosure. All such variations and modifications are intended to be within the scope of the present disclosure and protected by the following claims. For example, various features of the present disclosure may be combined in accordance with the following embodiments.

[0109] First embodiment 1. A fluid ejection device, comprising: A plurality of fluid ejectors, each fluid ejector comprising: A pumping chamber; a membrane defining a top wall of the pumping chamber; an actuator configured to expel fluid from the pumping chamber and disposed directly on the membrane; A nozzle; a fluid ejector comprising: a feed channel fluidly connected to each pumping chamber; at least one compliant structure formed in a surface of the feed channel, the at least one compliant structure being more compliant than the surface of the feed channel; and Equipped with the at least one compliant structure comprises at least one dummy nozzle formed in a surface of the feed channel; Each dummy nozzle includes a first opening on an inner surface of the surface and a second opening on an outer surface of the surface; A fluid ejection device, wherein the plurality of fluid ejector nozzles are disposed along a first line, and the feed channel is laterally offset from the first line.

[0110] Embodiment 2 2. The fluid ejector of embodiment 1, wherein each actuator comprises a piezoelectric layer disposed on the membrane.

[0111] Third embodiment 2. The fluid ejection device of embodiment 1, wherein a convex meniscus forms at the second opening in response to an increase in fluid pressure in the feed channel.

[0112] Fourth embodiment 2. The fluid ejection device of embodiment 1, wherein a nozzle of each fluid ejector is formed in a nozzle layer, and the dummy nozzle is formed in the nozzle layer.

[0113] Fifth embodiment 2. The fluid ejection device of embodiment 1, wherein the dummy nozzle is substantially the same size as the nozzle.

[0114] Sixth embodiment 2. The fluid ejection device of embodiment 1, wherein a nozzle of each fluid ejector is formed in a nozzle layer, the nozzle layer forming a surface of the feed channel.

[0115] Seventh embodiment A fluid ejection device as described in embodiment 6, wherein actuation of one of the actuators causes a change in fluid pressure in the feed channel, and the at least one compliant structure is configured to at least partially dampen the change in fluid pressure in the feed channel.

[0116] Embodiment 8 1. A method of manufacturing a fluid ejector, comprising: forming a plurality of nozzles in a nozzle layer; forming at least one compliant structure in the nozzle layer, the at least one compliant structure being more compliant than the nozzle layer; attaching the nozzle layer to a substrate comprising a plurality of fluid ejectors, each fluid ejector comprising a pumping chamber, a membrane defining a top wall of the pumping chamber, and an actuator configured to eject fluid from the pumping chamber, the actuator disposed directly on the membrane; Including, forming at least one compliant structure in the nozzle layer includes forming at least one dummy nozzle in the nozzle layer; each dummy nozzle defines a first opening on an interior surface of the nozzle layer and a second opening on an exterior surface of the nozzle layer; Attaching the nozzle layer to a substrate comprising a plurality of fluid ejectors defines feed channels fluidly connecting to each of the pumping chambers; The method, wherein the plurality of nozzles are disposed along a first line, and the feed channel is laterally offset from the first line.

[0117] Embodiment 9 9. The method of embodiment 8, wherein each actuator comprises a piezoelectric layer disposed on the membrane.

[0118] Embodiment 10 9. The method of embodiment 8, wherein forming at least one compliant structure in the nozzle layer comprises forming a plurality of recesses in the nozzle layer and disposing a membrane over the recesses.

[0119] Embodiment 11 11. The method of embodiment 10, wherein disposing a membrane across the recesses includes depositing a membrane layer across a top surface of the nozzle layer and removing a portion of the membrane layer across each nozzle.

[0120] Embodiment 12 9. The method of embodiment 8, wherein forming a plurality of nozzles includes forming the plurality of nozzles in a first layer, and forming at least one compliant structure includes forming the at least one compliant structure in a second layer, and attaching the first layer to the second layer.

[0121] Embodiment 13 The method of embodiment 8, wherein forming at least one compliant structure in the nozzle layer includes forming the at least one compliant structure in a first layer and attaching the first layer to a second layer having the plurality of nozzles formed therein, the first layer and the second layer together forming the nozzle layer.

[0122] Embodiment 14 2. The fluid ejection device of embodiment 1, wherein the fluid pressure in the feed channel is not high enough to cause fluid to be ejected from the at least one dummy nozzle.

[0123] Embodiment 15 2. The fluid ejection device of embodiment 1, wherein each fluid ejector has an inlet passage fluidly connecting the feed channel and a pumping chamber of the fluid ejector.

[0124] Embodiment 16 1. A method of operating a fluid ejector, comprising: actuating a fluid ejector in a fluid ejection device having a plurality of fluid ejectors, actuation of the fluid ejector causing a change in fluid pressure in a feed channel fluidly connected to the fluid ejector, each fluid ejector comprising a pumping chamber, a membrane defining a top wall of the pumping chamber, an actuator configured to eject fluid from the pumping chamber and disposed directly on the membrane, and a nozzle; deflecting a meniscus of fluid into a dummy nozzle formed in the feed channel due to the change in fluid pressure; Including, The method, wherein the nozzles of the plurality of fluid ejectors are disposed along a first line, and the feed channel is laterally offset from the first line.

[0125] Embodiment 17 17. The method of embodiment 16, wherein the step of activating any of the plurality of fluid ejectors does not cause fluid to be ejected from the dummy nozzle.

[0126] Embodiment 18 17. The method of embodiment 16, wherein each actuator comprises a piezoelectric layer disposed on the membrane.

[0127] Embodiment 19 1. A fluid ejection device, comprising: A plurality of fluid ejectors, each fluid ejector comprising: A pumping chamber; an actuator configured to expel fluid from the pumping chamber; A nozzle; a fluid ejector comprising: a feed channel fluidly connected to each pumping chamber; at least one compliant structure formed in a surface of the feed channel, the at least one compliant structure being more compliant than the surface of the feed channel; and Equipped with The at least one compliant structure comprises: a recess formed below a surface of the feed channel; a membrane disposed between the recess and the feed channel; Equipped with the membrane is configured to seal the recess from the feed channel; the recess is configured to be vented to the outside atmosphere via a fluid connection between the recess and an opening in a bottom surface of the substrate. Fluid ejection device.

[0128] Embodiment 20 20. The fluid ejection device of embodiment 19, wherein each fluid ejector includes a nozzle formed in the nozzle layer.

[0129] Embodiment 21 21. The fluid ejection device of embodiment 20, wherein the recess is formed in the nozzle layer.

[0130] Embodiment 22 21. The fluid ejection device of embodiment 20, wherein the nozzle layer is silicon and the membrane is silicon.

[0131] Embodiment 23 20. The fluid ejection device of embodiment 19, wherein each fluid ejector includes an actuator and a nozzle, and actuation of the actuator is configured to eject liquid from a corresponding nozzle.

[0132] Embodiment 24 A fluid ejection device as described in embodiment 23, wherein actuation of the actuator changes the fluid pressure in the feed channel, and the at least one compliant structure is configured to at least partially damp the change in fluid pressure in the feed channel.

[0133] Embodiment 25 20. The fluid ejection device of embodiment 19, wherein the recess is a plurality of recesses. [Explanation of symbols]

[0134] 100 print heads 110 Substrate 410 Casing 420 Upper Interposer 422 Fluid supply inlet 428 Fluid return outlet 430 Lower Interposer 432 Fluid Supply Chamber 436 Fluid Return Chamber 440 Lower divider 474 Flow Path 530 Upper divider

Claims

1. 1. A fluid ejection device comprising: A plurality of fluid ejectors, each fluid ejector comprising: A pumping chamber; an actuator configured to expel fluid from the pumping chamber; a nozzle defining an opening in a bottom surface of the substrate; a fluid ejector comprising: a feed channel fluidly connected to each pumping chamber; at least one compliant structure formed in a surface of the feed channel, the at least one compliant structure being more compliant than the surface of the feed channel; Equipped with The at least one compliant structure comprises: a plurality of recesses formed below a surface of the feed channel; one or more membranes disposed between the plurality of recesses and the feed channel; Equipped with the one or more membranes are configured to seal the plurality of recesses from the feed channel; the plurality of recesses are configured to be vented to the outside atmosphere via one or more fluid connections between the plurality of recesses and an opening in a bottom surface of the substrate. Fluid ejection device.

2. The fluid ejection device of claim 1 , wherein each fluid ejector comprises a nozzle formed in a nozzle layer.

3. The fluid ejection device of claim 2 , wherein the plurality of recesses are formed in the nozzle layer.

4. The fluid ejector of claim 2 , wherein the nozzle layer is silicon and the one or more membranes are silicon.

5. The fluid ejection device of claim 1 , wherein each fluid ejector includes an actuator and a nozzle, and actuation of the actuator is configured to eject liquid from a corresponding nozzle.

6. 6. The fluid ejection device of claim 5, wherein actuation of the actuator changes fluid pressure in the feed channel, and the at least one compliant structure is configured to at least partially damp the change in fluid pressure in the feed channel.

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