JP2011500374A - Print head with pressure buffering structure - Google Patents

Abstract

An excellent ink jet print head is provided.
An ink jet print head is provided. The print head includes a plurality of nozzle assemblies, a nozzle plate covering the plurality of nozzle assemblies, and an ink supply system for supplying ink to the plurality of nozzle assemblies, the at least one defined by a portion of the nozzle plate The ink supply system with a conduit wall and at least one pressure buffering structure disposed on a portion of the nozzle plate. This pressure buffering structure buffers ink pressure fluctuations in the ink supply system.
[Selection] Figure 14

Description

  The present invention relates to the field of printers, and specifically to the field of inkjet printheads. The present invention was developed primarily to improve the print quality and reliability of high resolution print heads.

  Many different types of printing have been invented, many of which are still in use today. Known printing forms have various ways of marking the print medium with a suitable marking medium. Commonly used printing forms include offset printing, laser printing / copying machines, dot matrix impact printers, thermal paper printers, film recorders, thermal wax printers, dye sublimation printers, drop-on-demand printers and continuous flow printers Inkjet printers. Each of these types of printers has its own advantages and problems when considering cost, speed, quality, reliability, simplicity of construction and operation, and the like.

  In recent years, the field of ink jet printing, in which each individual ink pixel is derived from one or more ink nozzles, has become increasingly popular, mainly due to its inexpensive and versatile nature.

  Many different techniques have been invented for inkjet printing. To review this field, see the article by J Moore, “Non-Impact Printing: Introduction and Historical Perspective”, Output Hard Copy Devices, R Dubeck and S Sherr, pp. 207-220. .

  There are many different types of inkjet printers themselves. The use of continuous ink flow in inkjet printing appears to date back to at least 1929, and Hansell U.S. Pat. No. 194001 discloses a simple form of continuous flow electrostatic inkjet printing.

  Sweet U.S. Pat. No. 3,596,275 also discloses a method of continuous ink jet printing that includes the step of adjusting the ink jet flow to cause ink drop separation by a high frequency electrostatic field. This technique is still used by several manufacturers, including Elmjet and Scitex (see also US Pat. No. 3,373,437 to Sweet et al.).

  A piezoelectric ink jet printer is also a form of an ink jet printing apparatus that is generally used. Piezoelectric systems include a Kyser et al. U.S. Pat. No. 3,946,398 (1970) utilizing a diaphragm operating mode, and a Zolten U.S. Pat. No. 3,683,212 which disclosed a piezoelectric crystal squeeze mode of operation. 1970), Stemme, US Pat. No. 3,747,120 (1972), which disclosed a bend mode of piezoelectric operation, and Hawkins, US Pat. No. 4,459,601, which disclosed piezoelectric push mode operation of an ink jet stream. And US Pat. No. 4,584,590 to Fischbeck, which discloses a shear mode type piezoelectric transducer element.

  Recently, thermal inkjet printing has become a very popular form of inkjet printing. Thermal ink jet printing techniques include those disclosed in Endo et al., British Patent No. 2,0071,62 (1979) and Vaught et al., US Pat. No. 4,490,728. Both of the above references relied on the activation of an electrothermal actuator that generated bubbles in a confined space such as a nozzle, thereby ejecting ink onto an appropriate print medium from an opening connected to this confined space. An inkjet printing technique is disclosed. Printing devices that use electrothermal actuators are manufactured by manufacturers such as Canon and Hewlett Packard.

  As can be seen, many different types of printing techniques can be used. Ideally, one printing technique should have several desirable attributes. This includes inexpensive structure and operation, high speed operation, safe long-term continuous operation, and the like. Each technology has its own advantages and disadvantages in the areas of cost, speed, quality, reliability, power usage, simplicity of structural operation, durability and consumable parts.

  Supplying ink from an ink reservoir to thousands of grouped nozzles is one particular challenge in high resolution page width printing. One problem is to avoid ink pressure surges when the nozzles stop printing. During printing, each nozzle acts like a pump, thereby refilling each nozzle chamber almost instantly with ink. Forming the nozzle chamber with a hydrophilic material (eg, silicon nitride, silicon dioxide, etc.) allows the nozzle chamber to be easily refilled during printing.

  Similarly, however, it is important that no ink overflows from the nozzle openings onto the print head surface when printing is stopped. This flooding property can adversely affect print quality and may require frequent cleaning by the printhead maintenance station. Overflow is a particular problem in high resolution page width print heads where a relatively large amount of ink moves towards each nozzle of the print head during printing. This large amount of moving ink has a corresponding inertia that can cause the ink to continue to leak from the nozzles even when printing is stopped. The greater the momentum of ink in the ink supply system, the greater the risk of overflow.

  For this reason, a pressure buffering structure that absorbs the pressure wave of the ink supplied to the nozzle in the ink supply system has been proposed. The applicant of the present application has previously described an air box in fluid communication with an ink supply line and having a buffering effect against ink pressure waves. In essence, it is desirable to provide some “give” in the ink supply system so that when printing is stopped, the pressure waves associated with the ink moving body can be absorbed.

  However, the use of air to absorb pressure surges is not entirely satisfactory. Ink outgassing is a particular problem with air cushioning structures. Outgassing is undesirable because air bubbles in the ink can cause the ink supply line to become clogged and the print head can even begin to drain ink critically. Further, the air cushioning structure is typically incorporated into an ink supply system located relatively far upstream of the inkjet nozzle, typically in a molded ink manifold to which the MEMS print head is mounted. Any downstream of such air cushioning ink will still have significant momentum, and this momentum will not be absorbed by the air cushioning structure. In addition, this problem adversely affects page-width printheads that carry large amounts of ink compared to conventional scans of the printhead.

  It would be desirable to provide an improved buffer structure that can absorb pressure surges in the ink supplied to the inkjet nozzles. In view of the problem of gas release, it is desirable to avoid air buffering as a means for buffering pressure surges. It would be further desirable to minimize the amount of ink between the buffer structure and the inkjet nozzle, thereby improving the effectiveness of any buffer system.

US Patent No. 194001 US Pat. No. 3,596,275 U.S. Pat. No. 3,373,437 U.S. Pat. No. 3,946,398 US Pat. No. 3,683,212 US Pat. No. 3,747,120 U.S. Pat. No. 4,459,601 U.S. Pat. No. 4,584,590 British Patent No. 2007162 U.S. Pat.No. 4,490,728

In a first aspect, the present invention provides:
A plurality of nozzle assemblies;
A nozzle plate covering the plurality of nozzle assemblies;
An ink supply system for supplying ink to the plurality of nozzle assemblies, comprising at least one conduit wall defined by a portion of the nozzle plate;
At least one pressure buffering structure disposed on the portion of the nozzle plate, thereby buffering pressure fluctuations of ink in the ink supply system;
An ink jet print head comprising:

Optionally, said at least one pressure buffering structure is
A vent defined in the portion of the nozzle plate;
A flexible membrane that hermetically covers the vent;
Is provided.

  Optionally, the Young's modulus of the flexible membrane is less than 1000 MPa.

  Optionally, the flexible membrane is composed of a polymer layer.

  Optionally, the polymer layer covers the nozzle plate.

  Optionally, the polymer layer is hydrophobic.

  Optionally, the polymer layer is resistant to removal by oxidizing plasma.

  Optionally, the polymer layer is composed of polydimethylsiloxane (PDMS).

  In another aspect, the print head comprises a plurality of the pressure buffering structures, and the polymer layer defines a plurality of flexible membranes for hermetically covering the respective vents.

In another aspect, the print head comprises at least 100 pressure buffering structures per cm ^{2 of the} nozzle plate.

  Optionally, the distance between the pressure buffering structure and at least one of the nozzle assemblies is less than 100 microns.

Optionally, each nozzle assembly is
A nozzle chamber having a nozzle opening and an ink inlet defined therein, wherein the ink inlet is in fluid communication with an ink supply channel;
An actuator for ejecting ink through the nozzle opening;
Is provided.

  Optionally, a respective nozzle chamber is formed on the surface of the printhead substrate, each nozzle chamber comprising a roof spaced from the substrate and a sidewall extending between the roof and the substrate, the nozzle opening being , Defined within the roof, each roof defining a portion of the nozzle plate.

  Optionally, the nozzle chambers are arranged as a plurality of rows, each row of nozzle chambers having an associated ink conduit extending longitudinally adjacent to the row, the ink conduits being connected to the nozzle plate. Defined between the substrates, wherein the ink conduit is at least partially defined by the at least one conduit wall.

  Optionally, the ink conduit supplies ink to a plurality of ink chambers through sidewall ink inlets defined in each nozzle chamber.

  Optionally, the ink conduit is shared in a pair of rows.

  Optionally, the ink conduits are connected to one or more ink inlet passages, each ink inlet passage extending from the ink conduit through the substrate, each ink inlet passage being connected to the nozzle plate. Extending substantially perpendicular to the ink conduit.

  Optionally, each ink inlet passage is aligned with a corresponding pressure buffering structure in the nozzle plate.

  Optionally, each ink inlet passage is connected to an ink supply channel defined in the substrate, and the ink supply channel receives ink from a surface of the substrate opposite the nozzle assembly.

In another aspect,
A substrate,
A plurality of nozzle assemblies formed on the substrate, each having a nozzle opening and an actuator for ejecting ink through the nozzle opening;
A drive circuit electrically connected to each of the actuators;
A nozzle plate covering the plurality of nozzle assemblies;
An ink supply system for supplying ink to the plurality of nozzle assemblies, comprising at least one conduit wall defined by a portion of the nozzle plate;
At least one pressure buffering structure disposed on the portion of the nozzle plate, thereby buffering pressure fluctuations of ink in the ink supply system;
A printhead integrated circuit is provided.

In a second aspect, the present invention provides:
An inkjet printhead having a plurality of nozzles;
At least one ink reservoir;
An ink supply system comprising: at least one pressure buffering structure for buffering pressure fluctuations received by the nozzles; and an ink supply system for supplying ink from the at least one ink reservoir to the plurality of nozzles. ,
An inkjet printer is provided wherein the distance between the at least one pressure buffering structure and at least one of the nozzles is less than 100 microns.

  Optionally, the distance between the at least one pressure buffering structure and at least one of the nozzles is less than 50 microns.

  Optionally, the distance between the at least one pressure buffering structure and at least one of the nozzles is less than 25 microns.

  Optionally, the print head comprises a portion of the ink supply system.

  Optionally, the ink supply system comprises at least 100 pressure buffer structures.

  Optionally, the ink supply system comprises at least 500 pressure buffer structures.

  Optionally, the ink supply system comprises at least 1000 pressure buffering structures.

Optionally, the print head is
A plurality of nozzle chambers;
A nozzle plate covering the plurality of nozzle chambers;
An ink supply system comprising at least one conduit wall defined by a portion of the nozzle plate for supplying ink to the plurality of nozzle chambers;
At least one pressure buffering structure disposed on the portion of the nozzle plate;
Is provided.

Optionally, at least one pressure buffering structure is
A vent defined in the portion of the nozzle plate;
A flexible membrane that hermetically covers the vent;
Is provided.

  Optionally, the Young's modulus of the flexible membrane is 1000 MPa.

  Optionally, the flexible membrane is composed of a polymer layer.

  Optionally, the polymer layer covers the nozzle plate.

  Optionally, the polymer layer is composed of polydimethylsiloxane (PDMS).

  In another aspect, the inkjet printer comprises a plurality of the pressure buffering structures, and the polymer layer defines a plurality of flexible membranes for hermetically covering the respective vents.

  Optionally, each nozzle chamber is formed on a surface of a printhead substrate, each nozzle chamber comprising a roof spaced from the substrate and a sidewall extending between the roof and the substrate, the roof comprising: With a nozzle opening defined therein, each roof defines a portion of the nozzle plate.

  Optionally, the nozzle chambers are arranged as a plurality of rows, each row of nozzle chambers having an associated ink conduit extending longitudinally adjacent to the row, the ink conduits being connected to the nozzle plate. Defined between the substrates, wherein the ink conduit is at least partially defined by the at least one conduit wall.

  Optionally, the ink conduit supplies ink to a plurality of ink chambers through sidewall ink inlets defined in each nozzle chamber.

  Optionally, the ink conduits are connected to one or more ink inlet passages, each ink inlet passage extending from the ink conduit through the substrate, each ink inlet passage being connected to the nozzle plate. Extending substantially perpendicular to the ink conduit.

  Optionally, each ink inlet passage is aligned with a corresponding pressure buffering structure in the nozzle plate.

  Optionally, each ink inlet passage is connected to an ink supply channel defined in the substrate, and the ink supply channel receives ink from a surface of the substrate opposite the nozzle chamber.

2 is a partial perspective view of an array of nozzle assemblies comprising nozzle chambers with sidewall ink inlets. FIG. FIG. 2 is a side view of the nozzle assembly unit cell shown in FIG. 1. FIG. 3 is a perspective view of the nozzle assembly shown in FIG. 2. 2 is a side view of a partially formed inkjet nozzle assembly immediately after depositing a roof material on a sacrificial photoresist scaffold. FIG. FIG. 5 is a perspective view of the nozzle assembly shown in FIG. 4. FIG. 5 is a side view of the nozzle assembly shown in FIG. 4 after nozzle rim etching. FIG. 7 is a perspective view of the nozzle assembly shown in FIG. 6. FIG. 7 is a side view of the nozzle assembly shown in FIG. 6 after nozzle opening and pressure vent etching. FIG. 9 is a perspective view of the nozzle assembly shown in FIG. 8. FIG. 9 is a side view of the nozzle assembly shown in FIG. 8 after application of a polymer layer. FIG. 11 is a perspective view of the nozzle assembly shown in FIG. 10. FIG. 11 is a side view of the nozzle assembly described in FIG. 10 after photopatterning to redefine the nozzle openings. FIG. 13 is a perspective view of the nozzle assembly shown in FIG. 12. FIG. 14 is a partial perspective view of the array of nozzle assemblies shown in FIG. 13. It is a perspective view of an inkjet printer. FIG. 16 is a perspective view of the ink jet printer shown in FIG. 15 with the ink cartridge exposed.

  An optional embodiment of the present invention will now be described by way of example only with reference to the accompanying drawings. The present invention can be used with any type of printhead. The applicant of the present invention has so far described a large number of inkjet printheads. Not all such printheads need to be described here for an understanding of the present invention. Nevertheless, the present invention is described below with respect to a thermal bubble forming ink jet print head. For the avoidance of doubt, all that are referred to herein as “inks” are any jettable printing fluid, such as conventional inks, invisible inks, fixing agents and other printables. Should be taken to mean fluid.

Printhead with Side Side Nozzle Chamber Inlet The present applicant has previously described a thermal bubble forming ink jet printhead in which ink is supplied from an ink conduit to the nozzle chamber through the side wall of the nozzle chamber. Such a printhead is described, for example, in earlier US Patent Application Publication No. 2007/0081044 by the applicant of the present invention, the contents of which are incorporated herein by reference.

  Referring to FIG. 1, a portion of an already disclosed printhead 1 with a plurality of nozzle assemblies is shown. 2 and 3 show a cross-sectional view and a cutaway perspective view of one of these nozzle assemblies.

  Each nozzle assembly includes a nozzle chamber 24 formed on the silicon wafer substrate 2 by MEMS manufacturing techniques. The nozzle chamber 24 is defined by a roof 21 and side walls 22 extending from the roof 21 to the silicon substrate 2. As shown in FIG. 1, each roof is defined by a portion of the nozzle plate 56 that extends across the ejection surface of the printhead 1. The nozzle plate 56 and the sidewall 22 are formed from the same material, which is deposited by PECVD over the sacrificial photoresist scaffold during MEMS fabrication. The nozzle plate 56 and the side wall 22 are generally formed from a ceramic material such as silicon dioxide or silicon nitride. These rigid materials have excellent properties for the robustness of the print head, and their inherent hydrophilicity is advantageous for supplying ink to the nozzle chamber 24 by capillary action.

  Returning to the details of the nozzle chambers 24, it can be seen that nozzle openings 26 are defined in the roof of each nozzle chamber 24. Each nozzle opening 26 is generally oval and has an associated nozzle rim 25. The nozzle rim 25 helps the directionality of the ink droplets during printing and reduces at least some of the ink overflowing from the nozzle openings 26. The actuator that ejects ink from the nozzle chamber 24 is a heater element 29 disposed below the nozzle opening 26 and suspended across the pit 8. A current is supplied to the heater element 29 through the electrode 9 connected to the driving circuit of the CMOS layer 5 of the substrate 2 underneath. When an electric current is passed through the heater element 29, the heater element 29 rapidly superheats the surrounding ink to form bubbles, and the bubbles push ink out of the nozzle openings. By suspending the heater element 29, when the ink is injected into the nozzle chamber 24, the heater element 29 is completely immersed in the ink. This improves the efficiency of the print head because less heat is dissipated into the underlying substrate 2 and more input energy is used to generate bubbles.

  As most clearly shown in FIG. 1, the nozzles are arranged in a plurality of rows, and an ink supply channel 27 extending longitudinally along the print head supplies ink to each nozzle in that row. Each row of nozzles has an associated ink conduit 23 extending longitudinally along that row. The ink conduit 23 is defined between the nozzle plate 56 and the substrate 2. The ink conduit 23 receives ink from the ink supply channel 27 through the ink inlet passage 15 and delivers ink to the respective nozzle chamber 24 through the side wall inlet defined in the side wall 22 of the respective nozzle chamber.

  The applicant of the present invention has heretofore described how the nozzle plate 56 of the print head 1 is made of a layer of hydrophobic material such as polydimethylsiloxane (PDMS) and perfluorinated polyethylene (PFPE). It was described whether it can be coated. This hydrophobic outer layer gives the print head 1 excellent properties for print head maintenance and reduces the risk of overflowing across the nozzle plate. Such a print head and its manufacturing method are described in detail in the earlier US patent application Ser. No. 11 / 685,084 filed on Mar. 12, 2007 by the assignee of the present invention. Which is incorporated herein by reference. Further improvements regarding the manufacture of this hydrophobically coated print head are described in earlier US patent application Ser. No. 11 / 740,925 filed Apr. 27, 2007 by the present applicant, The contents of which are incorporated herein by cross reference.

Printhead incorporating pressure buffering structure The manufacturing process for a printhead incorporating a pressure buffering structure will now be described. An inkjet nozzle assembly partially formed during the manufacturing stage shown in FIGS. 4 and 5 has already been described in detail by the applicant of the present invention (the contents of which are incorporated herein by reference, US Pat. (See published application 2007/0081044). For simplicity of description, similar features described in connection with the print head 1 are described with similar reference numerals in the following description.

  As shown in FIGS. 4 and 5, the inkjet nozzle assembly includes a nozzle chamber 24 and an ink conduit 23 defined by a roof 21 and a side wall 22 extending from the roof to the substrate 2. The roof 21 and sidewalls 22 are constructed, for example, by depositing a silicon nitride roof material 20 on the sacrificial photoresist scaffold 16. This photoresist 16 will be removed by oxidizing plasma in a later stage of printhead manufacture.

  Referring to FIGS. 6 and 7, the next step is to define an oval nozzle rim 25 in the roof 21 by etching the roof material 20 by 2 microns. As most clearly shown in FIG. 7, the elliptical rim 25 includes two coaxial rim lips 25a and 25b.

  In the process shown in US 2007/0081044, an elliptical nozzle opening 26 is etched in the next manufacturing stage by etching through the remaining roof material 20 bounded by the nozzle rim 25. Is defined. However, in the present invention, the vent hole 60 is etched simultaneously with the nozzle opening 26. As shown in FIGS. 8 and 9, the vent 60 is located in the roof 21 and is positioned directly above the ink inlet passage 15 that is still filled with photoresist in this manufacturing stage.

  Referring to FIGS. 10 and 11, in the next manufacturing stage, a thin layer of polymer material 100 (about 1 micron) is deposited over the roof 21 (and indeed the entire nozzle plate 56). The polymer 100 covers the vent hole 60 and temporarily covers the nozzle opening 26.

  The polymer material 100 can be resistant to ashing in an oxidizing plasma for easy ashing of the photoresist at a later stage. However, as described in US patent application Ser. No. 11 / 740,925 filed Apr. 27, 2007 by the applicant of the present invention, any reciprocity with the ashing process of polymer 100 is: It can be avoided by employing metal film protection of polymer 100.

  The polymer 100 should have some degree of flexibility or elasticity. Optionally, the stiffness of polymer 100 is relatively low. Optionally, the polymer 100 has a Young's modulus of less than 1000 MPa, typically on the order of about 500 MPa. Optionally, polymer 100 should also be relatively hydrophobic. The Applicant has identified a group of polymer materials that meet the above requirements of being hydrophobic, resistant to ashing, and having low stiffness. These materials are generally polymerized siloxanes or fluorinated polyolefins. More specifically, both polydimethylsiloxane (PDMS) and perfluorinated polyethylene (PFPE) have been shown to be particularly advantageous. PDMS is a preferred material. Another advantage of these materials is that they generally have excellent adhesion to ceramics such as silicon dioxide and silicon nitride that form the nozzle plate 56. Another advantage of these materials is that they can be photopatterned, which makes them particularly suitable for use in MEMS processes. For example, PDMS can be cured with UV light, which allows the unexposed areas of PDMS to be removed relatively easily.

  Referring now to FIGS. 12 and 13, after the polymer 100 is deposited, the polymer layer is photopatterned to remove the material deposited in the nozzle openings 26. Photopatterning can include exposing the polymer layer 100 other than the region of the polymer layer 100 in the nozzle opening 26 with UV light.

  Accordingly, as shown in FIGS. 12 and 13, each air hole 60 is hermetically covered by the elastically deformable polymer film layer 100, and is formed on the roof 21 on each ink inlet passage 15. A pressure buffer structure 70 is formed. Then, standard MEMS processing steps (back etching of ink supply channel 27, wafer thinning and ashing of photoresist 16) provide the printhead 200 shown in FIG.

  The ink flow characteristics of the print head 200 shown in FIG. 14 are improved by the pressure buffering structure 70 as compared with the print head 1 shown in FIG. These structures 70 absorb pressure surges in the ink by allowing the flexible polymer layer 100 on the vent 60 to rise outward during the pressure surge. Therefore, the buffer structure 70 minimizes the amount of ink that can overflow from the nozzle openings 26 when printing is stopped. The buffer structure 70 is particularly effective when the polymer 100 has low rigidity (for example, Young's modulus is less than 1000 MPa). As mentioned above, PDMS is particularly effective in this respect.

  Furthermore, these buffer structures 70 are arranged adjacent to the respective nozzle chambers 24. Optionally, each buffer structure is within a nozzle assembly or nozzle opening 26 within less than 100 microns, optionally less than 50 microns, or optionally less than 25 microns. Therefore, the amount of ink between the buffer structure 70 and the nozzle opening 26 is relatively small compared to the prior art buffer structure. This improves the buffering effect and minimizes ink overflow due to pressure surges.

Further, since the buffer structure 70 is formed by a MEMS manufacturing process, a large number of these structures can be provided on a single printhead. This large increase in the buffer structure 70 on the print head typically results in a pressure buffer compared to prior art designs that generally include a much smaller number of buffer structures further upstream of the nozzle chamber 24. The effect is improved. The area nozzle density of the page width print head by the applicant of this application will have at least 10,000 nozzles per cm ^{2 of} the print head surface. According to the invention, the print head has at least 100, at least 500 or at least 1000 buffer structures per cm ² of the print head surface (or nozzle plate).

  Another advantage of the printhead according to the invention is that the printhead maintains all the advantages of having a hydrophobic printhead surface. Further, due to the hydrophobic nature of the print head surface coupled to the pressure buffer structure 70, overflow of the print head surface is synergistically minimized. On the other hand, the pressure buffer structure 70 minimizes the pressure surge received at the nozzle opening 26, while the pressure surge reaches the nozzle opening 26 due to the hydrophobicity of the print head surface comparable to the hydrophobic wall of the nozzle chamber 24. Even so, ink leakage from the nozzle openings 26 is minimized. It will be appreciated that this synergistic effect provided by the print head according to the present invention is particularly effective in minimizing the overflow of the print head surface.

  Obviously, the print head described herein can be used in an inkjet printer. 15 and 16 show a typical page width inkjet printer 210 described in US Patent Application Publication No. 2005/0168543 by the applicant of the present application. Printer 210 includes a plurality of ink cartridges 211 in fluid communication with a print head (not shown in FIGS. 15 and 16). Each ink cartridge 211 supplies ink to a different color channel in the print head. A color channel typically includes a row of one or more nozzles.

  Those skilled in the art will appreciate that many variations and / or modifications may be made to the invention shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. . Accordingly, the embodiments of the invention are to be considered in all respects only as illustrative and not restrictive.

Claims (20)

A plurality of nozzle assemblies;
A nozzle plate covering the plurality of nozzle assemblies;
An ink supply system for supplying ink to the plurality of nozzle assemblies, the ink supply system comprising at least one conduit wall defined by a portion of the nozzle plate;
At least one pressure buffering structure disposed on the portion of the nozzle plate, thereby buffering pressure fluctuations of ink in the ink supply system;
An inkjet printhead comprising: The at least one pressure buffering structure comprises:
A vent defined in the portion of the nozzle plate;
A flexible membrane that hermetically covers the vent;
An ink jet print head according to claim 1.   The ink jet print head according to claim 2, wherein the flexible film has a Young's modulus of less than 1000 MPa.   The ink jet print head according to claim 2, wherein the flexible film is composed of a polymer layer.   The ink jet print head of claim 4, wherein the polymer layer covers the nozzle plate.   The ink jet print head of claim 4, wherein the polymer layer is hydrophobic.   The ink jet print head of claim 4, wherein the polymer layer is resistant to removal by oxidizing plasma.   The ink jet print head of claim 4, wherein the polymer layer is composed of polydimethylsiloxane (PDMS). The inkjet print head further includes a plurality of the pressure buffering structures,
The polymer layer defines a plurality of flexible membranes for hermetically covering each vent;
The ink jet print head according to claim 4. The inkjet print head of claim 1, further comprising at least 100 pressure buffering structures per 1 cm ^{2 of the} nozzle plate.   The inkjet printhead of claim 1, wherein a distance between at least one of the nozzle assemblies and the pressure buffering structure is less than 100 microns. Each nozzle assembly
A nozzle chamber having a nozzle opening and an ink inlet defined therein, wherein the ink inlet is in fluid communication with an ink supply channel;
An actuator for ejecting ink through the nozzle opening;
An ink jet print head according to claim 1. Each nozzle chamber is formed on the surface of the printhead substrate,
Each nozzle chamber comprises a roof spaced from the substrate and a sidewall extending between the roof and the substrate;
The nozzle opening is defined in the roof;
Each roof defines a portion of the nozzle plate;
The ink jet print head according to claim 12. The nozzle chambers are arranged in a plurality of rows;
Each row of nozzle chambers has an associated ink conduit extending longitudinally adjacent said row;
The ink conduit is defined between the nozzle plate and the substrate;
The inkjet printhead of claim 13, wherein the ink conduit is at least partially defined by the at least one conduit wall.   The inkjet printhead of claim 14, wherein the ink conduit supplies ink to a plurality of ink chambers through sidewall ink inlets defined in respective nozzle chambers.   The ink jet printhead of claim 14, wherein the ink conduit is shared in a pair of rows. The ink conduit is connected to one or more ink inlet passages;
A respective ink inlet passage extends from the ink conduit through the substrate;
The inkjet printhead of claim 14, wherein each ink inlet passage extends substantially perpendicular to the nozzle plate and the ink conduit.   The inkjet printhead of claim 17, wherein each ink inlet passage is aligned with a corresponding pressure buffering structure in the nozzle plate.   18. Each ink inlet passage is connected to an ink supply channel defined in the substrate, wherein the ink supply channel receives ink from a surface of the substrate opposite the nozzle assembly. Inkjet print head. A substrate,
A plurality of nozzle assemblies formed on the substrate, each nozzle assembly having a nozzle opening and an actuator for ejecting ink through the nozzle opening;
A drive circuit electrically connected to each of the actuators;
A nozzle plate covering the plurality of nozzle assemblies;
An ink supply system for supplying ink to the plurality of nozzle assemblies, the ink supply system comprising at least one conduit wall defined by a portion of the nozzle plate;
At least one pressure buffering structure disposed on the portion of the nozzle plate, thereby buffering pressure fluctuations of ink in the ink supply system;
A printhead integrated circuit comprising:

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