KR101019281B1 - Printhead with elongate nozzles - Google Patents

Abstract

Each has an array of ink chambers having a nozzle 25 and a long actuator for ejecting ink through the nozzle 25, the nozzle 25 having a long dimension of elongate shape aligned with the length of the long actuator. Having an inkjet printhead.

Printhead, Nozzle, MEMS, Ink Drop Tube, Anchor, Ink Chamber

Description

Printhead with long nozzle {PRINTHEAD WITH ELONGATE NOZZLES}

The present invention relates to the field of microelectromechanical system (MEMS) mechanisms, and discloses an inkjet printing system using MEMS technology.

Various methods, systems and apparatuses associated with the present invention are disclosed in the following US patent / patent applications filed by the applicant or assignee of the present invention.

The disclosures of these applications and patents are incorporated herein by reference.

The present invention includes the injection of ink droplets through the formation of gas or vapor bubbles in the bubble-forming liquid. The principle of this is outlined in US Pat. No. 3,747,120 (Stemme). Each pixel of the printed image is derived from ink droplets ejected from one or more ink nozzles. In recent years, inkjet printing has increased in popularity mainly due to its inexpensive and versatile characteristics. Many different aspects and techniques for inkjet printing are described in detail in the above cross-reference documents.

Nozzle packing density, or number of nozzles per square mm of printhead, is associated with print resolution and manufacturing cost. In this regard, efforts are continuously made to increase the nozzle packing density. As a result, each nozzle structure is configured to reduce the space between adjacent nozzles. One such configuration employs an extended ink chamber and similarly extended ink jet actuators to reduce the space between adjacent nozzles. However, ejecting a substantial proportion of the ink out of the nozzle in the extended ink chamber involves significant hydraulic pressure loss. To overcome this loss, the actuator uses additional energy to generate pressure pulsations in the ink sufficient to eject the ink droplets. Therefore, the efficiency of the entire printhead is lower than the actuators in the ink chamber, which are relatively less extended.

Accordingly, the present invention,

A row of ink chambers each having a nozzle and an extension actuator for ejecting ink through the nozzle;

An inkjet printhead comprising a nozzle having an extended form as an elongated dimension and an aligned dimension of the elongated actuator.

By extending the nozzle and aligning it with the actuator, the nozzle shape corresponds more closely to the shape of the pressure pulsation that the actuator forms in the ink. This makes it possible for the pressure pulsation to eject ink more easily through the nozzle. Less hydraulic pressure loss is achieved because less fluidic drag is applied when the ink pressed by the pressure pulsation is ejected in a thin form through the nozzle. This also improves the operating efficiency of the printhead. Preferably the nozzle is an elliptical nozzle. In another preferred form, the actuator is a thermal actuator having an extended heater element that produces steam bubbles for injecting steam bubbles through the nozzle. In some embodiments each ink chamber belonging to a row has a plurality of extension nozzles aligned with extension actuators. Optionally, each ink chamber belonging to a row has a plurality of extension actuators and a plurality of corresponding extension nozzles, respectively.

In the first embodiment, the present invention,

Ink chambers each having a nozzle and an extension actuator for ejecting ink through the nozzle, the ink chambers forming a row;

 The nozzle has an elongate form with the long dimension aligned with the dimension of the elongate actuator.

Optionally, the nozzle is elliptical.

Optionally, the actuator is a thermal actuator that has an extended heater member for generating steam bubbles and injects steam bubbles through the nozzle.

Optionally, each ink chamber in the row has a plurality of extending nozzles aligned with the extending actuators.

Optionally, each ink chamber in the row has a plurality of extending nozzles each corresponding to a plurality of extending actuators.

In another form, the apparatus further includes a driving circuit for providing an actuator driving signal to each actuator through a pair of electrodes, the actuator extending between two contacts on the pair of electrodes. Each of the thermal actuators has a member, and the thermal actuators are all provided with an inkjet printhead having a single planar structure.

Optionally, a trench etched into the drive circuitry extends between the electrodes.

Optionally, each ink chamber has a plurality of nozzles, and during use, the actuator ejects ink simultaneously through all the nozzles of the ink chamber.

Optionally, each ink chamber has two nozzles.

Optionally, the nozzles of each ink chamber are mounted on a line parallel to the length of the heater element, with the central axes of the nozzles being regularly spaced along the heater element.

Optionally, the nozzles are elliptical.

Optionally, the long axes of the elliptical nozzles are aligned with the alignment line.

Optionally, the drive circuit has a drive field effect transistor (FET) for each thermal actuator, the drive voltage of the drive FET being less than 5 volts.

Optionally, the drive voltage of the drive FET is 2.5 volts.

In another form, an inkjet printhead is further provided that includes an ink conduit in fluid communication with a plurality of ink chamber openings between a nozzle plate and an underlying wafer.

In another form, the method further includes a plurality of ink inlets defined in the wafer substrate;

Each ink conduit is provided with an inkjet printhead in fluid communication with at least one ink inlet containing ink for supplying ink to the ink chamber.

Optionally, each ink conduit is in fluid communication with two ink inlets.

Optionally, each ink inlet has an ink permeable trap and a sized vent so that the surface tension of the ink meniscus prevents ink leakage across the vent; The ink permeable trap directs gas bubbles through the vents and causes them to be released into the atmosphere.

Optionally, the ink chamber has an elongate shape so that the two sidewalls are relatively long compared to the other sidewalls, and the sidewall is in one of the long sidewalls that allows ink to refill the ink chamber.

Optionally, the nozzle centers are mounted in rows so that the nozzle centers are in line, and the nozzle pitch along each row is greater than 1000 nozzles per inch.

In a second aspect of the invention,

Row nozzles;

A plurality of actuators for ejecting ink through the nozzles so as to form a bulb shape before the ink droplets attached to the droplet stem are separated when the ink droplet tube is ruptured;

A plurality of ink drop pipe anchors positioned between adjacent actuators,

In use, adjacent actuators simultaneously eject ink and ink droplet tube anchors provide an inkjet printhead that combines, in a single droplet, the solids simultaneously ejected by adjacent nozzles.

Optionally, the adjacent actuators are two thermal actuators that eject ink through a single elliptical nozzle.

Optionally, the thermal actuators are both heater elements connected in series for simultaneous actuation and injection.

Optionally, the two heater elements are part of a single beam of heater elements suspended at their ends and midpoints.

Optionally, the heater member has a taper portion with maximum electrical resistance such that the vapor bubbles start at the maximum electrical resistance portion.

Optionally, the heater members are on opposite sides of the ink drop tube anchor such that the trajectory of the ink jetted by one heater member intersects the trajectory of ink jetted by the other heater member.

Optionally, the heater members are in an ink chamber adjacent to the ink drop tube anchor at an adjacent boundary.

Optionally, the heater members are in a single ink chamber.

Optionally, the ink ejected by adjacent actuators is in fluid communication prior to operation.

Optionally, the heater member is formed of TiAIN.

Optionally, the nozzles are elliptical.

Optionally, the major axes of the elliptical nozzles are aligned in a straight line.

Optionally, the drive circuit has a drive field effect transistor (FET) for each thermal actuator, the drive voltage of the drive FET being less than 5 volts.

Optionally, the drive voltage of the drive FET is 2.5 volts.

In still another aspect, an inkjet printhead is provided further comprising an ink conduit in fluid communication with a plurality of ink chamber openings between the nozzle plate and the lower wafer.

In yet another form, it further comprises a plurality of ink inlets defined in the wafer substrate;

Each ink conduit is provided with an inkjet printhead in fluid communication with at least one ink inlet for receiving and supplying ink to the ink chamber.

Optionally, each ink conduit is in fluid communication with two ink inlets.

Optionally, each ink inlet has an ink permeable trap and a sized vent so that the surface tension of the ink meniscus prevents ink leakage across the vent; In use,

The ink permeable trap directs gas bubbles through the vents and causes them to be released into the atmosphere.

Optionally, the ink chamber has an extended form so that the two sidewalls are relatively long compared to the other sidewalls, and the opening is in one of the long sidewalls that allows ink to refill the ink chamber.

Optionally, the nozzles are mounted in rows so that the nozzle centers are in line, and the nozzle pitch is greater than 1000 nozzles per inch along each row.

In a third aspect, the present invention,

Each of the ink chambers having a ink refilling gap and a nozzle, and an actuator for injecting ink through the nozzle, the ink chambers forming a row; And,

Provided is an inkjet printhead including a fluid flow rectifying valve in an ink refilling gap such that hydraulic resistance is less applied to ink flowing into the ink chamber than ink flowing out of the ink chamber.

Optionally, the rectifying valve is a Tesla valve having a main conduit, a secondary conduit, and at least one secondary conduit; In use, the ink flow out of the ink chamber is divided into a main flow and a secondary flow, so that when the ink flows out of the ink chamber, the secondary flow is combined with the main flow to pressurize the main flow.

Optionally, the Tesla valve has two secondary conduits opposite the main conduits.

Optionally, during use, when the ink enters the ink chamber, the upstream openings of the secondary conduit are on a plane parallel to the flow direction and the downstream opening is parallel to the flow from the main conduit downstream opening. Direct to all adjacent secondary flows.

Optionally, while the ink flows out of the ink chamber, the downstream openings of the secondary conduit are on opposite sides of the main conduit face across the main conduit in a flow direction.

In another form, each actuator further comprises a drive circuit for providing an actuator drive signal through a pair of electrodes, each of which has an extension heater element extending between two contacts on the pair of electrodes, all of The thermal actuator is a single planar structure.

Optionally, the trench etched into the drive circuitry extends between the electrodes.

Optionally, each ink chamber has a plurality of nozzles; In use,

The actuator sprays ink simultaneously through the nozzles of all the ink chambers.

Optionally, each ink chamber has two nozzles.

Optionally, the nozzles of each ink chamber are mounted in a line parallel to the length of the heater member, with the central axes of the nozzles being regularly spaced along the heater member.

Optionally, the nozzles are elliptical.

Optionally, the long axes of the elliptical nozzles are aligned in a straight line.

Optionally, the drive circuit has a drive field effect transistor (FET) for each thermal actuator, the drive voltage of the drive FET being less than 5 volts.

Optionally, the drive voltage of the drive FET is 2.5 volts.

In another form, an inkjet printhead is further provided between the nozzle plate and the lower wafer, the ink conduit in fluid communication with the plurality of ink chamber openings.

In yet another form, it further comprises a plurality of ink inlets defined in the wafer substrate;

Each ink conduit is provided with an inkjet printhead in fluid communication with at least one ink inlet for receiving and supplying ink to the ink chamber.

Optionally, each ink conduit is in fluid communication with two ink inlets.

Optionally, each ink inlet has an ink permeable trap and a sized vent so that the surface tension of the ink meniscus prevents ink leakage across the vent; In use,

The ink permeable trap directs gas bubbles through the vents and causes them to be released into the atmosphere.

Optionally, the ink chamber has an extended form so that the two sidewalls are relatively long compared to the other sidewalls, and the opening is in one of the long sidewalls that allows ink to refill the ink chamber.

Optionally, the nozzles are mounted in rows so that the nozzle centers are in line, and the nozzle pitch is greater than 1000 nozzles per inch along each row.

In a fourth aspect, the present invention,

Ink nozzles each having a nozzle, an ink drop pipe anchor, and an actuator for injecting ink through the nozzle, and forming a row;

Ink ejected from the nozzle is attached to the ink droplet tube anchor by an ink stem until the stem is broken, thereby providing an inkjet printhead in which the ink forms dispersed droplets.

Optionally, the ink drop anchor is in the form of a columnar with a shape resembling a nozzle.

Optionally, the axis of the ink drop tube anchor and the center axis of the nozzle are collinear.

Optionally, each ink chamber has two actuators, each actuator having a heater element for generating vapor bubbles to inject ink through the nozzle, and the ink droplet tube anchor being located between the heater members.

Optionally, the actuator has a plurality of heater members connected in parallel as cross bracing structures extending between the heater members, the cross supporting structures also providing ink droplet tube angles.

Optionally, the actuator has two parallel heater elements, and the cross support structure is a single beam having an irregularly positioned surface of the ink drop tube actuator.

In another form, further comprising a drive circuit for providing an actuator drive signal to each actuator through a pair of electrodes, each of the actuators having an extended heater member extending between two contacts on the electrodes of this pair, Both are single plane thermal actuators.

Optionally, trenches etched into the drive circuitry extend between the electrodes.

Optionally, each ink chamber has a plurality of nozzles; In use,

The actuator sprays ink simultaneously through all the nozzles of the ink chamber.

Optionally, each ink chamber has two nozzles.

Optionally, the nozzles of each ink chamber are provided on a line parallel to the longitudinal direction of the heater member, with the central axis of the nozzles regularly spaced along the heater member.

Optionally, the nozzles are elliptical.

Optionally, the long axes of the elliptical nozzles are aligned in a straight line.

Optionally, the drive circuit has a drive field effect transistor (FET) for each thermal actuator, the drive voltage of the drive FET being less than 5 volts.

Optionally, the drive voltage of the drive FET is 2.5 volts.

In another form, an inkjet printhead is further provided between the nozzle plate and the lower wafer, the ink conduit in fluid communication with the plurality of ink chamber openings.

In yet another form, it further comprises a plurality of ink inlets defined in the wafer substrate;

Each ink conduit is provided with an inkjet printhead in fluid communication with at least one ink inlet for receiving and supplying ink to the ink chamber.

Optionally, each ink conduit is in fluid communication with two ink inlets.

Optionally, each ink inlet has an ink permeable trap and a sized vent so that the surface tension of the ink meniscus prevents ink leakage across the vent; In use,

The ink permeable trap directs gas bubbles through the vents and causes them to be released into the atmosphere.

Optionally, the ink chamber has an extended form so that the two sidewalls are relatively long compared to the other sidewalls, and the opening is in one of the long sidewalls that allows ink to refill the ink chamber.

In a fifth aspect, the present invention,

Each of the ink chambers having a nozzle and an actuator for ejecting ink through the nozzle, the ink chambers forming a row;

The actuator, in use, initiates a quadrupole pressure pulse that is symmetrical about two orthogonal axes parallel to the nozzle face, with the orthogonal axes traversing mutual orthogonal axes extending through the nozzle center.

Optionally, the actuator is a thermal actuator having heater elements that generate vapor bubbles and eject ink.

Optionally, the actuator has two parallel current paths with two heater elements connected in series along each current path causing a four-pole pressure pulsation.

Optionally, the heater members comprise bubble nucleation sections that heat up faster than other parts of the current path.

Optionally, the bubble nucleators are between portions of the current path that have greater thermal inertia.

Optionally, the bubble nucleators are tight radius curves between relatively large radius curves, so that currents clustering around the tight radius curves are more than those of the relatively larger radius curves. Generates heat of resistance.

Optionally, the heater elements are hung in the ink chamber.

Optionally, the actuator has a cross support structure extending between intermediate points on the parallel current paths.

Optionally, the cross support structure connecting each current path results in increased thermal inertia.

Optionally, the cross support structure provides an ink drop tube anchor.

In still another aspect, the apparatus further includes a driving circuit for providing an actuator driving signal to each actuator through a pair of electrodes, each of which includes an extension heater member extending between two contacts on the pair of electrodes. It is a thermal actuator having, the thermal actuator is provided with an inkjet printhead all of a single planar structure.

Optionally, the trench etched into the drive circuitry extends between the electrodes.

Optionally, each ink chamber has a plurality of nozzles, and during use, the actuator ejects ink simultaneously through all the nozzles of the ink chamber.

Optionally, each ink chamber has two nozzles.

Optionally, the nozzles of each ink chamber are mounted on a line parallel to the length of the heater element, with the central axes of the nozzles being regularly spaced along the heater element.

Optionally, the nozzles are elliptical.

Optionally, the major axes of the elliptical nozzles are aligned in a straight line.

Optionally, the drive circuit has a drive field effect transistor (FET) for each thermal actuator, the drive voltage of the drive FET being less than 5 volts.

Optionally, the drive voltage of the drive FET is 2.5 volts.

Optionally, the nozzles are mounted in rows so that the nozzle centers are in line, and the nozzle pitch is greater than 1000 nozzles per inch along each row.

In a sixth aspect, the present invention provides a

Each of the ink chambers having a nozzle and a thermal actuator for generating steam bubbles for ejecting ink through the nozzle and forming heat;

The thermal actuator has a pair of contacts and at least two parallel current paths between the contacts, each current path having a plurality of heater elements constituting the core of the vapor bubbles.

Optionally, the heater elements form their respective bubble nuclei simultaneously with the operation of all actuators.

Optionally, the actuator has two parallel current paths with two heater elements connected in series along each current path.

Optionally, the heater members include bubble nucleation portions that heat up faster than other portions of the current path.

Optionally, bubble nucleation portions are between portions of the current path having relatively large thermal inertia.

Optionally, the bubble nucleators are tight radius curves between relatively large radius curves, so that currents clustering around the tight radius curves are more than those of the relatively larger radius curves. Generates heat of resistance.

Optionally, the heater elements are hung in the ink chamber.

Optionally, the thermal actuator has a cross support structure extending between intermediate points on the parallel current paths.

Optionally, the cross support structure connecting each current path results in increased thermal inertia.

Optionally, the cross support structure provides an ink drop tube anchor.

Optionally, the actuator initiates a quadrupole pressure pulsation that is symmetric about two orthogonal axes parallel to the nozzle plane, which orthogonal axes intersect mutually orthogonal axes extending through the nozzle center.

Optionally, the thermal actuator is formed of TiAlN.

In another form, further comprising a drive circuit for providing actuator drive signals to each actuator through a pair of electrodes, wherein the actuator is a thermal actuator, each elongated heater extending between two contacts on the paired electrode With the member, the thermal actuators are all provided with an inkjet printhead having a single planar structure.

Optionally, the trench etched into the drive circuitry extends between the electrodes.

Optionally, each of the ink chambers has a plurality of nozzles, and the actuator sprays ink through all the nozzles of the chamber simultaneously during use.

Optionally, each ink chamber has two nozzles.

Optionally, the nozzles in each chamber are aligned on a line parallel to the length of the heater element, with the central axis of the nozzles regularly spaced along the heater element.

Optionally, the nozzle is elliptical.

Optionally, the long axes of the elliptical nozzles are aligned.

Optionally, the drive circuit has a drive field effect transistor (FET) for each of the thermal actuators, the drive voltage of the drive FET being less than 5 volts.

In a seventh aspect, the present invention provides a

An array of ink chambers each having a nozzle and a plurality of heater members suspended to immerse in ink for generating vapor bubbles for ejecting ink through the nozzle; And,

An inkjet printhead comprising a cross bracing structure for maintaining a gap between heater elements is provided.

Optionally, the heater elements nucleate their respective bubbles simultaneously with the operation of all actuators.

Optionally, the ink chamber has a pair of contacts having two parallel current paths extending between the contacts and each having two heater elements connected in series.

Optionally, the heater members include bubble nucleation portions that heat up faster than other portions of the current path.

Optionally, the bubble nucleators are between portions of the current path having greater thermal inertia.

Optionally, the cross support structure is formed integrally with the heater members and extends between intermediate points on the parallel current path.

Optionally, the cross support structure provides a greater portion of the thermal inertia in the current path.

Optionally, the heater element initiates a quadrupole pressure pulsation that is symmetrical about two orthogonal axes parallel to the nozzle face, the orthogonal axes traversing mutually orthogonal axes extending through the nozzle center.

Optionally, the thermal members and contacts are formed of TiAlN.

Optionally, the cross support structure provides a droplet tube anchor.

Optionally, the actuator initiates a quadrupole pressure pulsation that is symmetrical about two orthogonal axes parallel to the nozzle face, the orthogonal axes traversing mutually orthogonal axes extending through the nozzle center.

In another form, the apparatus further includes a driving circuit for providing actuator driving signals to each actuator via a pair of electrodes, the actuator being a thermal actuator, each of which extends between two contacts on a pair of electrodes. In addition, the thermal actuators are all provided with an inkjet printhead having a single planar structure.

Optionally, the trench etched into the drive circuitry extends between the electrodes.

Optionally, each of the ink chambers has a plurality of nozzles, and the actuator sprays ink through all the nozzles of the chamber simultaneously during use.

Optionally, each ink chamber has two nozzles.

Optionally, the nozzles in each chamber are aligned on a line parallel to the length of the heater element, with the central axis of the nozzles regularly spaced along the heater element.

Optionally, the nozzle is elliptical.

Optionally, the long axes of the elliptical nozzles are aligned.

Optionally, the drive circuit has a drive field effect transistor (FET) for each of the thermal actuators, the drive voltage of the drive FET being less than 5 volts.

Optionally, the drive voltage of the drive FET is 2.5 volts.

In an eighth aspect, the present invention provides a

An array of ink chambers, each having a nozzle and an actuator for ejecting ink through the nozzle;

The nozzle provides an inkjet printhead comprising a nozzle rim forming a nozzle aperture and localized irregularities on the nozzle rim extending toward the center of the nozzle opening.

Optionally, the localized irregularity is a droplet tube anchor positioned to attach the droplet tube in preference to all other points on the nozzle rim.

Optionally, the localized irregularity is a lateral spur that extends from the nozzle rim into the nozzle opening.

Optionally, the actuator is a thermal actuator having a suspended beam heater member for immersion in ink.

Optionally, all the protrusions in the arrangement are parallel and have the same position with respect to the heater element.

In another form, the apparatus further includes a driving circuit for providing actuator driving signals to each actuator via a pair of electrodes, the actuator being a thermal actuator, each of which extends between two contacts on a pair of electrodes. In addition, the thermal actuators are all provided with an inkjet printhead having a single planar structure.

Optionally, the trench etched into the drive circuitry extends between the electrodes.

Optionally, each of the ink chambers has a plurality of nozzles, and the actuator sprays ink through all the nozzles of the chamber simultaneously during use.

Optionally, each ink chamber has two nozzles.

Optionally, the nozzles in each chamber are aligned on a line parallel to the length of the heater element, with the central axis of the nozzles regularly spaced along the heater element.

Optionally, the nozzle is elliptical.

Optionally, the long axes of the elliptical nozzles are aligned.

Optionally, the drive circuit has a drive field effect transistor (FET) for each of the thermal actuators, the drive voltage of the drive FET being less than 5 volts.

Optionally, the drive voltage of the drive FET is 2.5 volts.

In another form, an inkjet printhead is provided that further includes an ink conduit in fluid communication with the openings of the plurality of ink chambers between the nozzle plate and the underlying wafer.

In another form, the method further comprises a plurality of ink inlets formed in the wafer substrate;

Each ink conduit is provided with an inkjet printhead in fluid communication with at least one ink inlet for receiving and supplying ink to the ink chamber.

Optionally, each ink conduit is in fluid communication with two ink inlets.

Optionally, each ink inlet has an ink permeable trap and an outlet sized such that the surface tension of the ink meniscus across the vent prevents ink leakage. ;

The ink permeable trap is directed to an outlet through which gas bubbles are discharged to the atmosphere during use.

Optionally, the ink chambers are elongated in shape so that the two sidewalls are long in relation to the other, and the openings for refilling the chamber with ink are on one of the long sidewalls.

Optionally, the nozzles are arranged in rows such that the nozzle center is collinear and the nozzle pitch along each row is greater than 1000 nozzles per inch.

The printhead according to the invention comprises a plurality of nozzles and a chamber and one or more heater elements corresponding to each nozzle. The minimum repeat units of the printhead have an ink supply inlet for supplying ink to one or more chambers. The entire nozzle array is formed by repeating these individual units. Such individual units are referred to hereinafter as "unit cells".

In addition, the term "ink" is used when referring to all sprayable liquids, and is not limited to traditional inks including colored dyes. Examples of achromatic inks include fixatives, infra-red absorber inks, functionalized chemicals, adhesives, biological fluids, medicines Includes water, water, and other solvents.

In addition, the ink or sprayable liquid does not necessarily necessarily be a liquid, but contains a suspension of solid particles.

1 shows a unit cell partially machined into an MEMS nozzle arrangement on a printhead according to the invention and cut along line A-A of FIG. 3;

2 shows a perspective view of the partially processed unit cell of FIG. 1;

3 shows an indication associated with etching of a heater element trench;

4 is a cross sectional view of a unit cell after trench etching;

5 is a perspective view of the unit cell shown in FIG. 4;

FIG. 6 is a mask associated with the deposition of the photoresist to be removed shown in FIG. 7; FIG.

7 is a partial enlarged view of the gaps between the end of the material to be removed and the sidewalls of the trench, showing the unit cell after deposition of the photoresist trench to be removed;

8 is a perspective view of the unit cell shown in FIG. 7;

9 shows the unit cell in which the reflow of the photoresist to be removed leads to the closing of the gap along the sidewalls of the trench;

10 is a perspective view of the unit cell shown in FIG. 9;

11 is a sectional view showing deposition of a heater material layer;

12 is a perspective view of the unit cell shown in FIG. 11;

FIG. 13 is a mask associated with metal etching of the heater material shown in FIG. 14; FIG.

14 is a cross-sectional view illustrating metal etching to form heater actuators;

15 is a perspective view of the unit cell shown in FIG. 14;

FIG. 16 is a mask associated with etching shown in FIG. 17; FIG.

17 shows deposition of the photoresist layer and subsequent etching of the ink inlet on top of the CMOS drive layer into the passivation layer;

18 is a perspective view of a unit cell shown in FIG. 17;

19 shows oxidation etching through a passivation layer and a CMOS layer into underlying silicon wafers;

20 is a perspective view of the unit cell shown in FIG. 19;

21 is deep anisotropic etching of an ink inlet into a silicon wafer;

22 is a perspective view of the unit cell shown in FIG. 21;

FIG. 23 is a mask associated with the photoresist etching shown in FIG. 24;

24 shows photoresist etching to form openings and sidewalls for the chamber loop;

25 is a perspective view of the unit cell shown in FIG. 24;

26 illustrates deposition of sidewalls and hazardous materials;

27 is a perspective view of the unit cell shown in FIG. 26;

FIG. 28 is a mask associated with nozzle rim etching shown in FIG. 29; FIG.

29 shows the etching of the roof layer for forming the nozzle opening rim;

30 is a perspective view of the unit cell shown in FIG. 29;

FIG. 31 is a mask associated with nozzle opening etching shown in FIG. 32;

32 shows the etching of the loop material to form elliptical nozzle openings;

33 is a perspective view of the unit cell shown in FIG. 32;

FIG. 34 shows an oxygen plasma release etch of the first and second removal layers; FIG.

35 is a perspective view of the unit cell shown in FIG. 34;

36 shows the unit cell after release etching and the opposite side of the wafer;

37 is a perspective view of the unit cell shown in FIG. 36;

FIG. 38 is a mask associated with the reverse etch shown in FIG. 39; FIG.

39 shows reverse etching of an ink supply channel into a wafer;

40 is a perspective view of the unit cell shown in FIG. 39;

41 shows wafer thinning by back etching;

42 is a perspective view of the unit cell shown in FIG. 41;

43 is a partial perspective view of a nozzle arrangement on a printhead in accordance with the present invention;

44 is a plan view of a unit cell;

45 is a perspective view of the unit cell shown in FIG. 44;

46 is a schematic plan view of two unit cells with only the roof layer removed, with an overview of the particular roof layer;

FIG. 47 is a schematic plan view of the two unit cells with only the overview of the nozzle opening, with the roof layer removed;

48 is a schematic partial plan view of unit cells with ink inlets on the sidewall of the chamber;

FIG. 49 shows only an overview of the nozzle opening, which is a schematic plan view of the unit cells with the roof layer removed;

50 is a partial plan view showing particles of the nozzle plate and the paper dust having a form in which the stiction is reduced;

51 is a partial plan view of a nozzle plate with remaining ink gutters;

FIG. 52 is a partial cross-sectional view illustrating the deposition of a SAC1 photoresist associated with the prior art used for avoiding stringers; FIG.

FIG. 53 is a partial cross-sectional view illustrating the deposition of a heater material layer onto the SAC1 photoresist scaffold deposited in FIG. 52;

54 is a schematic partial top view of a unit cell with multiple nozzles and actuators in each chamber;

55 to 59 are schematic cross sectional views of the ink chamber shown in FIG. 44 in the sequential step of droplet injection;

FIG. 60 is a schematic perspective view of a nozzle with a droplet tube anchor as shown in FIG. 61;

61 is a plan view of the nozzle opening with the droplet tube anchors arranged in the center;

62 is a schematic plan view of a unit cell with a simple 'theta' type heater element and with the roof layer removed;

FIG. 63 shows a theta-type heater element with a sharp contraction in the cross section on the cross bar to position the droplet tube; FIG.

64 shows a theta-type heater element with a formation at a cross section on a cross bar to position the droplet tube;

65 shows two bars and four twisted heat members;

FIG. 66 is a schematic plan view of a unit cell with a Tesla valve to correct ink flow through chamber inlets; FIG.

67 is a schematic perspective view of a nozzle with protrusions extending into the nozzle opening for controlled droplet misspraying.

<Drawing symbol>

In the description that follows, corresponding reference numerals relate to corresponding parts. For convenience, the members indicated by the respective reference numbers are listed below.

1: Nozzle Unit Cell

2: silicon wafer

3: top aluminum metal layer in CMOS metal layers

4: passivation layer

5: CVD oxide layer

6: Ink inlet opening in top aluminum metal layer (3)

7: Pit opening in the top aluminum metal layer (3)

8: hole

9: electrodes

10: SAC1 photoresist layer

11: Heater material (TiAlN)

12: thermal actuator

13: photoresist layer

14: ink inlet opening portion etched through the photoresist layer

15: Ink inlet passage

16: SAC2 photoresist layer

17: chamber side wall openings

18: front channel priming unit

19: boundary formation at the ink inlet

20: chamber roof layer

21: loop

22: sidewalls

23: ink conduit

24: nozzle chambers

25: oval nozzle rim

25 (a): inner lip

25 (b): outer lip

26: nozzle opening

27: ink supply channel

28: contact

29: heater member

30: bubble collection

32: bubble holding structure

34: ink permeable structure

36: bleed hole

38: ink chamber

40: double row filter

42: Paper Dust

44: ink gutter

46: gap between SAC1 and trench sidewalls

48: trench sidewalls

50: raised lip of SAC1 around trench end

52: thinner slope of heater material

54: cold spots between heater elements connected in series

56: nozzle plate

58: columnar protrusions

60: sidewall ink opening

62: ink refilling opening

64: ink

66: bubble

68: expanding ink meniscus

70: ink bulb

72: drop tube

74: drop point

76: nozzle center line

78: droplet misspray

80: droplet

82: satellite drop

84: droplet tube anchor

86: maximum resistance or 'hot spot'

88: Fire one of the drop pipe anchors

90: semicircular current path

92: 'cold spot'

94: center bar

96: curve of larger radius

98: tight radius curve

100: outer end of the curved curve

102: inner end of the curved curve

104: ink refilling opening

106: calibration valve (Tesla valve)

108: main conduit

110: secondary conduit

112: side projection from the nozzle rim

Hereinafter, preferred embodiments of the present invention are described by way of example only with reference to the accompanying drawings.

MEMS Manufacture process( MEMS Manufacturing Process )

In this MEMS manufacturing process, nozzle structures are stacked on a silicon wafer after the CMOS process is completed. 2 is a partial cross-sectional perspective view of the nozzle unit cell 1 after the completion of the CMOS process and before the MEMS process.

During the CMOS process of the wafer, four metal layers are deposited on the silicon wafer 2, which are intersperated between interlayer dielectric (ILD) layers. These four metal layers are represented by M1, M2, M3 and M4 layers, which are sequentially stacked on the wafer during the CMOS process. These CMOS layers provide all the driver circuitry and logic for the operation of the printhead.

In the completed printhead, each heater material actuator is connected to the CMOS through a pair of electrodes formed on the outermost M4 layer. Thus, this M4 CMOS layer is the foundation for subsequent MEMS processing of the wafer. This M4 layer also forms bonding pads along the longitudinal edges of each printhead integrated circuit. Such bonding pads (not shown) make it possible to connect the CMOS to a microprocessor via wire bonds extending from the bonding pad.

1 and 2 show an aluminum M4 layer 3 with a passivation layer 4 deposited thereon (these figures show only the MEMS characteristics of the M4 layer; the main CMOS characteristics of the M4 layer are nozzles). Located outside the unit cell). This M4 layer 3 is 1 micron thick and is self-deposited over a 2 micron CVD oxide layer 5. As shown in FIGS. 1 and 2, the M4 layer 3 has an ink inlet opening 6 and a pit opening 7. These openings form the locations of the ink inlets and the holes formed as a result of the MEMS process.

Before starting the MEMS process of the unit cell 1, bonding pads are formed by etching through the passivation layer 4 along the longitudinal edge of each printhead integrated circuit. This etching reveals the M4 layer 3 at the bonding pad position. This nozzle unit cell 1 is completely masked as a photoresist for this step and therefore is not affected by etching.

3 to 5, the hole 8 is etched through the passivation layer 4 and the CVD oxide layer 5 in the first step of the MEMS process. This etching is formed using a photoresist layer (not shown) exposed by the dark tone hole mask shown in FIG. This hole 8 is 2 microns deep and is measured from the top of the M4 layer 3. At the same time as the hole 8 is etched, the electrodes 9 are formed by partially revealing the M4 layer 3 through the passivation layer 4 on the other side of the hole. In the finished nozzle, the heater material is suspended across the hole 8 between the electrodes 9.

In the next step (FIGS. 6-8), the holes 8 are filled with a first sacrificial layer ("SAC1") of the photoresist 10. A 2 micron layer of high viscosity photoresist is first made by spinning onto the wafer and then exposed using the dark tint mask shown in FIG. 6. This SAC1 photoresist 10 forms a scaffold on the other side of the hole 8 for the deposition of a heater material across the subsequent electrode 9. Therefore, it is important that the SAC1 photoresist 10 has a top surface in the same plane as the top surface of the electrodes 9. At the same time, the SAC1 photoresist must completely fill the hole 8 to avoid 'stringers' of the conductive heater material that short across the electrode while extending across the hole.

Typically, when filling trenches with photoresist, the photoresist needs to be exposed outside the circumferential wall of the trench in order to ensure that the photoresist is full with respect to the walls of the trench, whereby the ' Stringer 'is avoided. However, this technique results in a raised (or spiked) rim of photoresist surrounding the trench. This is undesirable in subsequent deposition steps in which the material is deposited unevenly on the vertical or angled surfaces on the raised rim-rim, so that less deposition material can be received than when the photoresist filling the trench is a horizontal plane. not. As a result, the thinly deposited region becomes 'resistance hotspots'.

As shown in FIG. 7, the process of the present invention deliberately exposes the SAC1 photoresist 10 into the peripheral walls of the aperture 8 (eg, within 0.5 micron) using the mask shown in FIG. 6. This allows the top surface of the SAC1 photoresist 10 to be planar so as to avoid the formation of any protruding regions of the photoresist around the peripheral rim of the hole 8.

After exposure of the SAC1 photoresist 10, the photoresist is reflowed by heating. The backflow of the photoresist causes flow to the holes 8 walls, allowing for full filling. 9 and 10 show the SAC1 photoresist after backflow. This photoresist has a planar top surface, meets the same surface as the top surface of the M4 layer 3, and forms the electrodes 9. Following backflow, the SAC1 photoresist 10 is U.V. hardened and / or hardbaked such that no backflow occurs during the subsequent deposition of the heater material.

11 and 12 show the unit cell after depositing a 0.5 micron heater material 11 over the SAC1 photoresist 10. By the countercurrent process described above, the heater material 11 is deposited flat on the planar layer over the electrodes 9 and the SAC1 photoresist 10. The heater material may be made of any suitable conductive material such as TiAl, TiN, TiAlN, TiAlSiN and the like. A typical heater material deposition process includes sequential deposition of a 100 Angstrom TiAl base layer, a 2500 Angstrom TiAlN layer, a 100 Angstroms TiAl base layer, and finally a 2500 Angstroms TiAlN addition layer.

13 to 15, in the next step, the heater material 11 layer is etched to form a thermal actuator 12. Each actuator 12 has contacts 28 that make electrical connections to the respective electrodes 9 on another side of the SAC1 photoresist 10. A heater element 29 spans between its corresponding contacts 28.

This etching is formed by a photoresist layer (not shown) exposed using the dark tint mask shown in FIG. As shown in FIG. 15, the heater member 12 is linear beam spanning between a pair of electrodes 9. However, this heater element 12 alternatively applies to other configurations, as described in the Applicant's US Pat. No. 6,755,509, the contents of which are hereby incorporated by reference. For example, the configuration of the void heater member 29 has the advantage of minimizing the effects of the harmful cavitation force on the heater material when the bubbles collapse during ink jetting. Another form of cavitation protection applies to things like 'bubble venting' with the use of self passivating materials. Such cavitation management techniques are described in detail in US patent application (docket MTC001US).

In the next sequence of steps, the ink inlets for the nozzles are etched through the passivation layer 4, the oxide layer 5 and the silicon wafer 2. During the CMOS process, each of the metal layers had an ink inlet opening (see, for example, the opening 6 in the M4 layer 3 in FIG. 1) etched in preparation for etching the ink inlet. . These metal layers, together with the scattered ILD layers, form a seal ring for the ink inlet to prevent ink from seeping into the CMOS layer.

16 to 18, a relatively thick layer of photoresist 13 is made by rotating onto a wafer and exposed using a dark tint mask shown in FIG. The thickness of the photoresist 13 required depends on the selectivity of the deep reactive ion etch (DRIE) used to etch the ink inlets. By having the ink inlet opening 14 formed in the photoresist 13, the wafer is ready for the subsequent etching step.

플라즈마)이 사용될 수 있다.In the first etching step (Figs. 19 and 20), the dielectric layers (passivation layer 4 and oxide layer 5) are etched down to below the silicon wafer. All standard oxide etching (e.g.,

Plasma) can be used.

In the second etching step (FIGS. 21 and 22), using the same photoresist mask 13, the ink inlet 15 is etched through the silicon wafer 2 to a depth of 25 microns. Standard anisotropic DRIEs such as Bosch etching (see US Pat. Nos. 6,501,893 and 6,284,148) can be used for such etching. In the subsequent etching of the ink inlet 15, the photoresist layer 13 is removed by plasma ashing.

In the next step, the ink inlet 15 is plugged into the photoresist, and a second lossy layer "SAC2" of the photoresist 16 is deposited on top of the SAC1 photoresist 10 and passivation layer 4. This SAC2 photoresist 16 acts as a scaffold for subsequent deposition of the roof material, forming loops and sidewalls for each nozzle chamber. 23 to 25, a high viscosity photoresist layer of 6 microns or less is made by rotating onto a wafer and exposed using a dark tint mask as shown in FIG.

As shown in Figures 23 and 25, this mask exposes sidewall openings 17 in the SAC2 photoresist 16 corresponding to the location of the chamber sidewalls and the sidewalls for the ink conduit. In addition, openings 18 and 19 are exposed adjacent to the plugged inlet 15 and the nozzle chamber inlet, respectively. These openings 18 and 19 will be filled with loop material in subsequent loop deposition steps and provide unique advantages to the nozzle design of the present invention. In particular, this opening 18 filled with loop material acts as a priming feature to help guide the ink from the inlet 15 to each nozzle chamber. This is described in more detail below. Openings 19 filled with loop material serve as filter structures and fluidic cross talk barriers. This helps to prevent air bubbles from entering the nozzle chambers and also to dissipate the pressure pulsations generated by the thermal actuator 12.

Referring to Figures 26 and 27, the next step is to deposit 3 micron loop material 20 on SAC2 photoresist 16 by PECVD. The loop material 20 fills the opening 17, opening 18, and opening 19 in the SAC 2 photoresist 16 with a nozzle chamber 24 having loops 21 and sidewalls 22. ). In addition, an ink conduit 23 for supplying ink to each nozzle chamber is formed during the deposition of the loop material 20. In addition, all priming parts and filter structures (not shown in FIGS. 26 and 27) are formed simultaneously. Loops 21, each corresponding to a separate nozzle chamber 24, span across the vicinity of the nozzle chambers in a row to form a continuous nozzle plate. The roof material 20 may be made of any suitable material such as silicon nitride, silicon oxide, silicon oxynitride, aluminum nitride, or the like.

Referring to FIGS. 28 to 30, the next step is to etch the 2 micron loop material 20 to form an elliptical nozzle rim 25 in the loop 21. This etching is formed using a photoresist layer (not shown) exposed by the dark rim mask shown in FIG. The elliptical rim 25 includes two coaxial rim lips 25a and 25b located above each thermal actuator 12.

31 to 33, the next step is to etch all remaining loop material 20 to form an elliptical nozzle aperture 26 in the loop 21, which is a rim 25. Bound by This etching is formed using a photoresist layer (not shown) exposed by the dark-masked roof mask shown in FIG. The elliptical nozzle opening 26 is located on the thermal actuator 12, as shown in FIG.

As the priming portions of all the MEMS nozzles are completely formed here, the next step is to remove the SAC1 photoresist layer 10 and the SAC2 photoresist layer 16 by O2 plasma ashing (FIGS. 34-35). After ashing, the thermal actuator 12 is suspended above the hole 8 in a single plane. Coplanar deposition of the contact 28 and heater element 29 makes the electrical connection with the electrode 9 efficient.

36 and 37 show the total thickness (150 microns) of the silicon wafer 2 after the SAC1 photoresist layer 10 and the SAC2 photoresist layer 16 are ashed.

38 to 40, once the MEMS process on the front side of the wafer is completed, ink supply channels 27 are etched from the back side of the wafer to meet the ink inlet 15 using standard anisotropic DRIE. . This backside etching is formed using a photoresist (not shown) exposed by a mask of dark hue as shown in FIG. The ink supply channel 27 fluidly connects the wafer back surface with the ink inlets 15.

Finally, referring to FIGS. 41 and 42, the wafer is thinned to 135 microns by backside etching. Figure 43 shows an arrangement of three adjacent nozzles in a sectional perspective view of a completed printhead integrated circuit. Each array of nozzles has a respective ink supply channel 27 that extends along its length and supplies ink to the plurality of ink inlets 15 in each array. These ink inlets alternately supply ink to the ink conduit 23 for each row, while each nozzle chamber receives ink from a common ink conduit for that row.

Aspects and Benefits of Certain Embodiments

Certain specific aspects of the present invention and the advantages of these aspects are described below with appropriate sub-heading. These aspects are to be considered in connection with all the drawings relevant to the present invention, unless specifically excluded in the context of the drawings, and in particular to those drawings to which reference is made.

Low loss electrodes Low Loss Electrodes )

41 and 42, the heater member 29 is suspended in the chamber. This ensures that the heater element is submerged in the ink when the chamber is primed. Fully submerging the heater element in the ink dramatically improves the efficiency of the printhead. By dissipating some heat to the underlying wafer substrate, more input energy is used to generate the vapor that injects the ink.

To suspend the heater element, a contact is used to support the heater element at its raised position. In essence, the contacts at the other end of the heater element may have a vertical portion or an inclined portion to connect respective electrodes on the CMOS driver to the heater element at the elevated position. However, the heater material is deposited thinner in the vertical or inclined plane than in the horizontal plane. In order to avoid undesirable resistive losses in relatively thin areas, the contact portion of the thermal actuator needs to be relatively large. Relatively large contacts occupy a significant area of the wafer and limit nozzle packing density.

In order to submerge the heater, the present invention etches holes or trenches 8 between the electrodes 9 to lower the level of the chamber bottom. As described above, a lossy photoresist layer (SAC) 10 (see FIG. 9) is deposited in the trench to provide a scaffold for the heater member. However, depositing the SAC 10 in the trench 8 and simply covering it with a layer of heater material may provide the separation between the SAC 10 and the sidewalls 48 of the trench 8 (as described above in connection with FIG. 7). Stringers forming in the gaps 46 may occur. Gaps are formed because it is difficult to accurately fit the sides of the mask and the trench 8. Typically, when the masked photoresist is exposed, gaps 46 form between the sides of the hole and the SAC. When the heater material layer is deposited, these gaps are filled to form a 'stringer' (as known). These stringers remain in the trench 8 after a metal etch (which specifies the heater element) and a release etch (last to remove the SAC). Steam generators fail because these stringers short the heater circuit.

52 and 53, a 'traditional' technique for avoiding stringers is shown. By creating a UV mask that exposes the SAC slightly larger than the trench 8, the SAC 10 will be deposited over the sidewalls 48 so that no gaps are formed at all. Unfortunately, this produces a raised lip 50 surrounding the top of the trench. When the heater material layer 11 is deposited (see FIG. 53), the heater material layer is thinner on the vertical or inclined surfaces 52 of the lip 50. After metal etching and release etching, these thin lip formations 52 remain, causing 'hotspots' to occur because localized thinning increases resistance. These hot spots affect the operation of the heater and typically shorten the heater life.

As noted above, the Applicant has discovered that the backflow of the SAC 10 closes the gaps 46 such that the scaffold between the electrodes 9 is completely flat. This makes it possible to planarize the entire thermal actuator 12. While the contacts are deposited directly onto the CMOS electrodes 9 and the hanging heater member 29, the planar structure of the thermal actuator avoids hot spots caused by the vertical or inclined surfaces, thereby avoiding an increase in the acceptable resistance loss. A much smaller structure can be achieved. Low resistive losses allow for efficient operation of suspended heater elements, while small contact sizes are convenient for tight nozzle packing on the printhead.

bracket Chamber  Multiple nozzles for Multiple Nozzles for each Chamber )

Referring to FIG. 49, the unit cell shown has two separate ink chambers 38, each chamber having a heater member 29 extending between pairs of individual contacts 28. As shown in FIG. Ink permeable structures 34 are located in the ink refill openings to allow ink to enter the chambers, which, in operation, these structures 34 may be of any reverse flow or acceptable level. Provide sufficient fluid resistance to reduce fluidic cross talk.

Ink is supplied from the opposite side of the wafer through the ink inlet 15. The primings 18 extend into the inlet openings in order to allow the ink meniscus to block ink flow without securing itself to the peripheral edge of the opening. Ink from the inlet 15 fills the ink conduits 23 on the side that feed into both chambers 38 of the unit cell.

Instead of one single nozzle per chamber, each chamber 38 has two nozzles 25. When the heater member 29 is activated (forms steam), two drops of ink are ejected; One drop is ejected from each nozzle 25. Individual droplets of ink have less volume than a single droplet injected when the chamber has only one nozzle. Print quality is improved by simultaneously ejecting multiple drops from a single chamber.

All nozzles have some misdirection to the sprayed droplets. Depending on the degree of misinjection, this can hinder print quality. Multiple nozzles are given to the chamber, each nozzle spraying a smaller amount of droplets, and also having a different misfiring. Some small drops misinjected in different directions are less detrimental to print quality than a single relatively large misinjected drop. Applicants have discovered that the human eye 'averages' the dots from each single droplet by averaging the five sprays of each small droplet, with significantly less total five sprays.

In addition, multiple nozzle chambers can eject droplets more effectively than a single nozzle chamber. The heater member 29 is a long hanging beam of TiAlN, and the vapor formed therein is long. Pressure pulsations generated by long vapors cause ink to be ejected through nozzles arranged in the center. However, some energy from the pressure pulsation causes the injection of fluid losses associated with inconsistencies in the geometry of the vapor and the nozzle.

Spacing some nozzles 25 along the length of the heater member 29 reduces the geometric mismatch between the vapor shape and the nozzle configuration through which ink is jetted.

Oval nozzle ( Elliptical Nozzle )

Similarly, the hydraulic resistance to droplet injection can be reduced by using elliptical nozzles. As shown in FIG. 44, vapor bubbles generated by the heater members 29 become long. The heater element is designed to heat evenly along most of its length so that bubble nucleation and growth are likewise substantially formed along its length. By concentrating the elliptical nozzle 25 over the hitty member 29 such that the major axis is parallel to the center line of the heater element, the bubble geometry generally coincides with the geometry of the nozzle. Therefore, the ink pushed accordingly by the pressure pulsation does not sharply change direction before being ejected through the nozzle and does not produce a high fluidic drag. Even with the smaller force required for droplet ejection, the printhead is more efficient.

In addition, elliptical nozzles are thinner than circular nozzles of equivalent aperture area. Therefore, the space between adjacent nozzles is reduced. This helps to increase the pitch of the nozzle and thereby improve print resolution.

adjacency Ink chamber  Ink chamber recharged through Ink Chamber Re - Filled Via Adjacent Ink Chamber )

Referring to FIG. 46, two opposing unit cells are shown. In this embodiment, the unit cell has four ink chambers 38. These chambers are formed by side walls 22 and ink-permeable structures 34. Each chamber has its own heater element 29. The heater members 29 are mounted in a series of connected pairs. Between each pair is a 'cold spot' 54 of relatively low resistance and / or relatively large heat sinking. This does not cause bubbles to nucleate in the cold spots 54 so that the cold spots become a common contact between the outer contacts 28 for each pair of heater elements.

The ink-permeable structures 34 baffle the pressure pulsations from each heater member 29 to refill the ink chamber 38 with ink after droplet injection while reducing fluid crosstalk between adjacent chambers. . It will be appreciated that this embodiment has many similarities shown in FIG. 49 described above. However, this embodiment effectively separates the relatively long chambers of FIG. 49 into two separate chambers. Moreover, this aligns the geometry of the vapor formed by the heater element 29 with the shape of the nozzle 25 to reduce the fluid loss during droplet injection. This adds some complexity to the fabrication process but is achieved without reducing the nozzle density.

Conduits (ink inlets 15 and supply conduits 23) for dispensing ink to all the ink chambers in the array may occupy an important part of the wafer area. This can be a factor in limiting the nozzle density on the printhead. By making part of some ink chambers of the ink flow path into other ink chambers, each chamber sufficiently eliminates fluid crosstalk while reducing the amount of wafer area lost to the ink supply conduit.

multiple Actuators  Ink chamber with individual nozzles ( Ink Chamber with Multiple  Actuators and Respective Nozzles )

Referring to Fig. 54, the unit cell shown has two chambers 38; Each chamber has two heater elements 29 and two nozzles 25. The effective reduction of the drop misdirection by using multiple nozzles per chamber is described in detail in connection with the embodiment shown in FIG. 49. Further advantages of dividing a single elongated chamber into separate chambers and allowing each to have its own actuator are detailed with reference to the embodiment shown in FIG. 46. This embodiment uses multiple nozzles and multiple actuators in each chamber to achieve more of the benefits of FIG. 46, which significantly reduces the complexity of the design. In a simplified design, the overall dimensions of the unit cell are reduced, thereby further increasing the nozzle density. In the illustrated embodiment, the footprint of the unit cell is 16 μm wide and 64 μm long.

The ink permeable structure 34 is a single column that opens to each chamber 38 upon ink refill, instead of the three spaced columns as in the embodiment of FIG. 46. This single circumference has a profiled cross section that is relatively less resistant to refill flow while relatively more resistant to sudden back flow from actuation pressure pulses. Have Both heater elements of each chamber can be deposited simultaneously and can be deposited with contacts 28 and cold spot feature 54, both chambers 38 having a common ink inlet 15 And ink are supplied from the supply conduit 23. These members also make it possible to reduce the footprint and are described in more detail below. The priming portions 18 were made integral with one of the chamber side walls 22 and with a wall ink conduit 23. Two intended properties of these members are to simplify manufacturing and to help maintain compact design.

Multiple for each drive circuit Chambers and  Multiple nozzles ( Multiple Chambers and Multiple  Nozzles for each Drive Circuit )

In Fig. 54, to simplify the CMOS driving circuit, the actuators are connected in series and thus fire identically in accordance with the same driving signal. In FIG. 46, unit cells and actuators adjacent to the nozzles are continuously connected in the same driving circuit. Of course, the actuators in adjacent chambers are also connected in parallel. In contrast, if the actuators in each chamber are in separate circuits, the CMOS driver circuit is more complex and the dimensions of the unit cell footprint increase. In printhead designs, the drop misdirection is addressed by replacing multiple smaller droplets, so combining a plurality of actuators and their respective nozzles into a common drive circuitry makes the printhead IC fabrication and nozzle density From the point of view of both, it is an efficient implementation.

High density Thermal Inkjet  Printhead ( High Density Thermal Inkjet Printhead )

By reducing the width of the unit cell, the printhead can have a nozzle pattern with a previously reduced nozzle density. Of course, relatively low nozzle densities have a corresponding effect on printhead size and / or print quality.

Traditionally, nozzle arrangements are aligned in pairs with the actuators for each arrangement extending in the opposite direction. These arrays are staggered against each other such that the print resolution (dots per inch) is twice the nozzle pitch (nozzles per inch) along each array. By configuring the components of the unit cell so that the overall width of the unit is reduced, the same number of nozzles can be aligned in a single arrangement instead of two staggered opposing arrangements without any loss of print resolution (d.p.i.). The embodiments shown in the accompanying figures achieve more nozzle pitches with 1000 noses per inch in each linear arrangement. In this nozzle pitch, when two opposing and staggered arrangements are considered, the printhead's print resolution is better than the picture (1600 dpi), sufficient capacity for redundancy of the nozzle, compensation for inactive nozzles, etc. The operating life of is left to be satisfactory. As described above, the embodiment shown in FIG. 54 has a footprint of 16 μm in width, so that the nozzle pitch along one row is approximately 1600 nozzles per inch. Thus, the offset rows of the two offsets yield a resolution of approximately 3200 d.p.i.

As an implementation of the particular advantage associated with the narrower unit cell, the applicant has focused on identifying and combining the number of members in order to reduce the corresponding dimensions of the structures in the print head. For example, elliptical nozzles, moving the ink inlet from the chamber, finer geometrical logic, and relatively short drive FETs (field effect transistors) can be found by the applicant to obtain some of the illustrated embodiments. Are members developed by. Each required member provided comes from traditional knowledge in this field, such as reducing the FET drive voltage from 5V to 2.5V, which is traditionally widely used to reduce transistor length.

low Stiction Printhead  surface( Reduced Stiction Printhead Surface )

As is known, static friction, or "stiction," causes dust particles to adhere to the nozzle plate, thereby cloging the movement of the nozzles. 50 shows a portion of the nozzle plate 56. Also, for clarity, nozzle apertures 26 and nozzle rims 25 are shown. The outer surface of the nozzle plate is encased in a pattern with columnar projections 58 extending a short distance from the plate surface. The nozzle plate may also be patterned into other surface shapes such as closely spaced ridges, corrugations or bumps. However, it is easy to produce a suitable UV mask for the columnar protrusions of the shown pattern, and it is a simple task to etch the cylinders on the outer surface.

By reducing the co-efficient of static friction, paper dust and other contaminants are less likely to interfere with the movement of the nozzles in the nozzle plate. Patterning the outside of the nozzle plate into a raised shape limits the surface area that the dust particles contact. If the particles can only contact the outer extremities of each shape, the friction between the particles and the nozzle plate is minimized, and the attachment is somewhat suitable. If particles are attached, it is more appropriate to remove them by a printhead maintenance cycle.

Entrance priming part ( Inlet Priming Feature )

Referring to FIG. 47, two unit cells are shown extending in opposite directions for each. An ink inlet passage 15 supplies ink to the four chambers 38 through a lateral ink conduit 23. Distributing ink to individual MEMS nozzles in an inkjet printhead through a micron sized conduit such as ink inlet 15 is complicated by factors that do not occur in macro-scale flow. Depending on the geometry of the opening, a meniscus can be formed, which itself can be 'pin' very strongly to the lip of the opening. Like bleed holes that hold ink while releasing trapped air bubbles, this may also be useful for a printhead, but this can also be a problem if you stop the flow of ink into some chambers. This may best occur the first time ink is primed into the printhead. If the ink meniscus is fixed at the ink inlet opening, the chambers supplied by the inlet will continue to be unprime.

To guide this, two priming parts 18 are formed which extend through the plane of the inlet opening 15. These primings 18 are columnar members extending from the inside of the nozzle plate (not shown) to the outer periphery of the inlet 15. A portion of each columnar member 18 is in the outer circumference such that the surface tension of the ink meniscus can form in the primings 18 at the ink inlet to draw the ink out of the inlet. This releases the meniscus from the outer circumferential portion and the flow to the ink chamber.

These primings 18 may take various forms, as long as there is a surface extending across the plane of the opening. Moreover, this priming part may be part integral with other nozzle shapes as shown in FIG.

Side entrance Ink chamber ( Side Entry Ink Chamber )

Referring to FIG. 48, a plurality of adjacent unit cells are shown. In this embodiment, the elongate heater elements 29 extend parallel to the ink distribution conduit 23. Thus, the elongated ink chamber 38 is aligned like the ink conduit 23. The sidewall openings 60 connect the chambers 38 to the ink conduit 23. By configuring the ink chambers with side inlets, ink refill time is reduced. The inlets are wider and therefore have a higher refill flow rate. The sidewall openings 60 have ink permeable structures 34 to maintain an acceptable level of fluid crosstalk.

Ink chamber  For inlet filter ( Inlet Filter for Ink Chamber )

Referring again to FIG. 47, the ink refill openings to each chamber 38 have a filter structure 40 to trap air bubbles or other contaminants. Air bubbles and solid contaminants in the ink inhibit the MEMS nozzle structure. Air bubbles are compressible at high pressure, and if they are trapped in the ink chamber, they can absorb pressure pulsations from the actuator, so solid contaminants can obviously obstruct the movement of the nozzle opening. This effectively makes it impossible to eject ink from the affected nozzles. By providing the filter structure 40 in an array behavior of obstructions extending across the flow direction through the opening, each row is spaced apart so that they are unable to adjust the shields in adjacent rows with respect to the flow direction and refill the ink. Contaminants rarely enter the chamber 38 unless the flow rate is excessively inhibited. These heats are offset relative to each other so that the induced disturbances have a minimal effect on the nozzle refill rate, while air bubbles or other contaminants tend to be relatively curved to increase the likelihood of being held by the shields 40. Follow the path The illustrated embodiment uses two rows of shields 40 in the form of a columnar member extending between the wafer substrate and the nozzle plate.

Multicolored Inkjet On the printhead  there is Between colors  Surface boundaries ( Intercolour Surface  Barriers in Multi Color Inkjet Printhead )

Referring now to FIG. 51, the outer surface of the nozzle 56 is shown for the unit cell, as shown in FIG. 46 described above. The nozzle openings 26 are located directly above the heater element (not shown) and a series of square-edged ink gutters 44 are provided on the nozzle plate 56 over the ink conduit 23. (See FIG. 46).

Sometimes inkjet printers have maintenance stations that cover the printhead when not in use. To remove excess ink from the nozzle plate, the capper can be separated to peel off the outer surface of the nozzle plate. This promotes the formation of the meniscus between the lid surface and the outside of the nozzle plate. Using the contact angle hysteresis associated with the angle at which the surface tension in the meniscus is in contact with the surface (more specifically, see co-pending USSN (Principal Number FND007US), incorporated herein by reference). ), Most of the ink that wets the outside of the nozzle plate can be collected and sucked by the meniscus between the lid and the nozzle plate. The ink is suitably deposited as large beads at the point where the lid is completely separated from the nozzle plate. Unintentionally some ink remains on the nozzle plate. If the printhead is a multi-color printhead, because the meniscus draws the ink over the entire surface of the nozzle plate, the ink remaining in or around the imparted nozzle opening is compared to that ejected by the nozzle. It will be different colors. Contamination of ink in one nozzle by ink from another nozzle can create a noticeable artifact in printing.

The formation of an exit groove that slides across the direction in which the lid is peeled off from the nozzle plate will result in the removal and retention of some of the ink in the meniscus. Unless the drain grooves collect all the ink in the meniscus, this significantly reduces the nozzle contamination caused by the different color inks.

Bubble Trap ( Bubble Trap )

Air bubbles in the ink are very bad for printhead operation. Air, or generally more precisely, gas, is compressible at high pressure and can absorb pressure pulsations from the actuator. If it is simply compressed corresponding to the jammed actuator, ink is not ejected from the nozzle. The trapped bubbles are purged from the printhead as a pressurized ink flow, while the extracted ink needs to be bloated and the pressurized flow well guides the fresh bubbles.

The embodiment shown in FIG. 46 has a base wrap at the ink inlet 15. This trap is formed by a bubble retention structure 32 and an outlet 36 formed in the roof layer. The bubble retaining structure is a continuous circumferential member 32 spaced around the inlet 15. As described above, the ink priming portions 18 serve two purposes and suitably form part of the bubble holding structure. In use, the ink permeable trap is directed to an outlet that discharges gas bubbles to the atmosphere. By trapping bubbles at the ink inlets and directing them to a small outlet, they are effectively removed from the ink flow without any ink leakage.

Multiple ink inlet flow paths Multiple Ink Inlet Flow Paths )

Supplying ink to the nozzle through a conduit extending from one side of the wafer to the other side allows more wafer area (on the ink ejection side) to have nozzles instead of a complex ink distribution system. However, deeply etched, micron sized holes through the wafer tend to impede movement from contaminants or air bubbles. This depletes the nozzle (s) supplied by the adversely affected inlet.

As best shown in FIG. 48, the printheads according to the present invention, at least two inks, supplying each chamber 38 through an ink conduit 23 between the nozzle plate and the underlying wafer. With inlets 15.

Feeding the plurality of chambers 38 and also guiding the ink conduit 23 which is supplied by itself by the plurality of ink inlets 15 may prevent the ink from being exhausted by an inlet which obstructs movement in the nozzle. Reduce If one inlet 15 is disturbed in motion, the ink conduit sucks more ink from the other inlets in the wafer.

Droplet tube  Anchors ( Droplet Stem Anchors )

Droplet tubes that attach the ejected ink to the ink in the chamber immediately prior to droplet separation can cause droplet misfiring. 55 to 59 show sequential steps of the droplet ejection process from the nozzle. In FIG. 55, the heater member 29 rapidly heats and vaporizes the ink 64 as soon as it contacts the surface to nucleate the bubble 66. This causes the ink meniscus 68 across the nozzle opening 26 to start bulging outward.

In FIG. 56, the bubble 66 continues to grow while the heater member 29 vaporizes more ink 64 in the chamber 38. Moreover, pressure pulsations from this growing bubble push the ink meniscus out of the nozzle opening 26. In FIG. 57, bubble 66 continues to grow and the ejected ink is spherical 70 connected to ink 64 in chamber 38 by a relatively thick droplet tube 72. In FIG.

In FIG. 58, bubbles grew to the point where they were discharged to the atmosphere through the nozzle opening 26. This is an important mechanism for avoiding cavitation corrosion of the heater member 29. Cavity corrosion occurs when bubbles collapse and return to a single point on the heater element surface. As the bubbles reach the singularity of the collapse point, the surface tension creates a high fluid force that can wear the heater material. By discharging bubbles, there is no collapse point on the heater member.

As shown in FIG. 58, when the bubbles are discharged, the droplet tube 72 may attach itself to a point 74 on the nozzle rim. Since the attachment point 74 is not on the centerline 76 of the nozzle opening 26, the spherical 70 of the ink has a centerline due to the tendency of the surface tension to reduce the surface area. Away from (78).

Referring to FIG. 59, the stem 52 eventually ruptures and ink droplets 80 form and continue on their trajectory to the print medium. Nevertheless, the misfiring 78 remains in the ink droplets 80 as well as in all satellite droplets 82. The discharged bubble becomes an expanded ink meniscus, which helps to retract into the chamber as the ink contracts to the nozzle opening 26.

60-67 show the design of a nozzle with a droplet tube anchor positioned positively where the droplet tube is attached. Knowing where the tube is stuck, reduce the misfiring or, in some cases, adjust the misfiring so that all nozzles are mistblasted in the same direction by approximately the same amount. However, droplet tube anchors can also perform secondary functions, which will be described below.

adjacency From actuators  Integrating Sprayed Ink ( Combining Ink Ejected from Adjacent Actuators )

60 and 61, the nozzle design shown has two actuators 29 for injecting ink through a single oval shaped nozzle 25. Actuators are both heater elements connected in series for simultaneous operation and injection. Both actuators 29 are part of a single beam of heater material, such as TiAlN, suspended at its end and midpoint. Both heater elements 29 have tapered sections 86 where electrical resistance is maximum. During operation, vapor bubbles occur at their maximum resistance portion or 'hot spot' 86.

Ink covering both heater elements 29 is connected to slots 88. These slots can be dimensioned to reduce fluidic crosstalk to the extent that the heater elements are in two separate ink chambers, or to such an extent that both members 29 are considered large enough to be considered in the same chamber 38. have.

While the ink sprayed by each actuator forms a spherical body attached by the tube, the ink surface tension is attempted to occupy a minimum surface area, with the tube at all other points on the nozzle rim 25. The heater elements 29 are positioned in association with the droplet tube anchor 84 to first attach to the anchor. Since the hot spots 86 are on opposite diameter sides of the anchor 84, the spherical objects of ink attached to the respective drop tubes are misinjected toward each other. After all, they meet directly on the anchors and the opposing opposing dusts cancel each other out, or at least the resulting mispolishing is very small.

Quadrupole  work( Quadrupolar Actuation )

62 to 65 show a plurality of embodiments of nozzles acting as quadrupoles. The operation of the quadrupole initiates a pressure pulsation at a position in the ink chamber with two orthogonal axes that are symmetrical. As the pulsations converge in the chamber, at least in the ideal case, the two symmetric axes push ink in the normal direction to both axes. In practice, some asymmetry means that the droplet direction is not exactly normal, but if pressure pulsations are initiated from a single point in the chamber, they are typically much more ideal.

Referring to FIG. 62, the unit cell represents two nozzles 25 in each chamber 38, each having a quadrupole thermal actuator 12. The heater member portion 29 of each actuator 12 has a form similar to the Greek letter 'theta'. Each actuator has two semicircular current paths 90 between the contacts 28. A central bar 94 extends between the midpoints of each current path. The entire theta-shaped structure is suspended in chamber 38 to minimize heat dissipation to the wafer and to maximize heater transfer to ink.

The center bar 94 is used for various purposes. Firstly, it provides a heater member having structural rigidity and support role. Without the center bar, the cyclical heating and cooling of the semicircular current paths causes some buckling into or out of the ground of FIG. 62. This is addressed by supporting semi-circles on the chamber floor or by a single support at each intermediate point. However, this increases the contact with the underlying wafer substrate and thereby increases the heat loss. The center bar 94 provides resistance to buckling while the heater member is suspended in the chamber.

Or the central bar 94 provides a 'cool spot' 92 at the midpoint of each semicircle. The thermal mass of the bar provides a small heat sink so that the junction between the bar and the semicircular current path heats up to the bubble nucleation temperature more slowly than either part of the junction. Likewise, the contacts 28 act as radiators such that bubble nucleation is directed to the middle of the arc between the contact and the center bar 94 and the junction. Vapor bubbles are nucleated at four locations in theta configuration, and these locations have quadrupoles that are symmetric about two orthogonal axes.

As a result, the central bar also provides a droplet tube anchor for further control over misfiring. If the droplet tube is attached to the bar instead of the point on the nozzle 25, the position of the center bar 94 will be below the nozzle 25 to minimize the surface tension area, so that the trace of the droplet is in the nozzle opening 26. It will be aligned closer to the central axis extending perpendicular to it.

63 and 64, the center bar 94 has a latch point 96 for positioning the base of the droplet tube. The latch point is simply a surface irregularity in which the surface tension of the ink can be 'pin' there. If the center bar 94 is not parallel to the plane of the nozzle opening 260, or if there is some asymmetry in the position of the bubble nucleation site, the droplet tube is caught off the center of the center bar 94. The surface irregularity 96 of the bar 94 tends to impede the surface tension of the droplet tube and anchor it to the middle of the bar, the surface irregularity 96 intersecting as shown in FIG. In part, it may be a sharp reduction or a boss as shown in Fig. 64. In either case, the droplet tube comes from the middle of the center bar 94 and thus in the droplet trajectory. Any misfiring of is minimized.

Double bar, four Kink , Heater element ( Dual Bar , Four Kink , Heat Element )

65 shows another quadrupole thermal actuator 12. Here again, there is a double current path 90 provided by a separate beam extending between the contacts 28. For clarity, other members of the unit cell are omitted.

The beams 90 are suspended in the chamber 28 to minimize heat loss to the wafer substrate, and each beam also has a double tight radius curve or twist between the relatively large radius 96 curves. 98). In this embodiment, the tight radius twists 98 act as hot spots where the vapor bubbles nucleate. This is because the current flow surrounding the twist 98 is concentrated inward in the radial direction of the member 102 and away from the outside of the radius 100. This acts like a localized constriction at the intersection that increases resistance at these points. In the large radius curves 96, the difference in current density between the inner and outer ends is much less so that the increase in resistance is less compared to the increase in resistance in the tight twists 98.

The tight twists 98 have relatively low bending resistance so that longitudinal expansion of the beam 90 during operation is accommodated without buckling inot or without the plane of the page. . This stabilizes the location of the hotspots in the chamber, thereby maintaining quadrupole symmetry and minimizing droplet misfiring.

Ink chamber  Calibration valve at the inlet Rectifying Valve at Ink Chamber Inlet )

The unit cell shown in FIG. 66 has a calibration valve 106 toward each chamber 38 at the ink refilling opening 104. The unusual calibration valve shown is known as a Tesla valve. The calibration valve provides less fluid resistance to ink flowing into the chamber than ink flows out of the chamber. This can be used to reduce fluid crosstalk between the chambers 38 as long as the ink refill time is not slowed down (and thus the printing speed is not slowed down).

For this example, the heater element 29 is a simple beam suspended in the chamber 38 between the contacts 28. Also, clearly, the nozzle rim is omitted, but the skilled worker will understand that it is centered on the heater element 29. Alternatively, the chamber 38 may have a plurality of nozzles, respectively, as described above.

The chambers 38 are supplied with ink from the ink inlet 15 through the side ink conduit 23. The tesla valve 106 at each refill opening 104 has a main conduit 108 between a pair of relatively smaller secondary conduits 110. When ink flows into the chamber 38, there is little resistance to flow through the main conduit 108 other than fluidic drag to the conduit itself wall. The upstream openings of the sub-conduits 110 do not face flow so that the main flow is hardly redirected there. The downstream opening is directed to all flows that are parallel and adjacent to the flow from the main conduit 108 downstream opening. Therefore, subconduit 110 has a negligibly small effect on the ink flow into chamber 38.

On operation, the pressure pulsation may create a back flow of ink backing out of the chamber 38 and into the side ink conduit 23. Backflow is harmful to droplet injection because it uses some energy from pressure pulsations. In addition, backflow can create fluid crosstalk that affects the spraying characteristics of adjacent chambers.

Tesla valve 106 suppresses all backflow by using flow from subconduits 110 to inhibit flow through main conduit 108. During reverse flow, the upstream opening of the secondary conduit 110 faces the flow direction. Thus it is an upstream opening to the main conduit 108. Pressure pulsations push ink along the main and secondary conduits, while the downstream openings of the secondary conduits 110 direct their ink flow across the main flow direction and against the main flow direction. This impingement of flow causes turbulence and fluid contraction in the main conduit 108. Therefore, backflow through the primary conduit 108 and the secondary conduit 110 is stifleed. As a high resistance to backflow, a larger portion of the pressure pulsation is used to eject ink droplets through the nozzle and the fluidic crosstalk is reduced.

Controlled Droplets  Five-component Controlled Drop Misdirection )

67 is a schematic perspective view of a nozzle in which droplet misspray is controlled. This is a different approach from the method of minimizing droplet misspray as described above. By intentionally misinjecting the droplets ejected by all the nozzles in the array by a controlled amount, this printed image (although somewhat offset from the nozzle arrangement) is equivalent to the image from the printhead where the droplet misspray is minimized.

While minimizing droplet misspraying, this approach uses droplet tube anchors 74 that are positioned such that the droplet tube attaches to the droplet tube anchors in preference to nozzle rim 25 or any other point on heater element 29. . However, in the nozzle design, the droplets do not form symmetrically around the droplet tube anchor, so the droplet trajectory is not perpendicular to the nozzle opening surface, which causes known misfirings of the same size and orientation as all other nozzles in the array. It may be located at a point.

This embodiment shown in FIG. 67 provides a droplet tube anchor at the end of a side spur 12 extending from the side of the nozzle rim 25 into the nozzle opening 26. These nozzles use a simple suspended beam heater element 29, which is easier to deposit and etch than theta-type heater (described above), but still controls droplet misfiring with a droplet tube anchor. It will be appreciated that the protrusion 112 is a shield that rubs the droplets from a conventional trajectory. However, if all of the protrusions in the nozzle arrangement are parallel and have the same position associated with the heater element, the five sprays across the entire arrangement will be uniform.

Although the invention has been described above with reference to specific embodiments, it will be understood by those skilled in the art that the invention is embodied in many other forms.

Claims (20)

An array of ink chambers each having a nozzle and an elongate actuator for ejecting ink through the nozzle; And the nozzle is an elliptical nozzle having a major axis aligned with an elongated actuator. delete The method of claim 1, And the actuator is a thermal actuator having a long heater element that produces a vapor bubble for ejecting through a nozzle. The method of claim 1, Wherein each ink chamber in the array has a plurality of elongated nozzles aligned with the elongated actuator. The method of claim 1, Wherein each ink chamber in the array has a plurality of elongate nozzles corresponding respectively to the plurality of elongate actuators. The method of claim 1, Further comprising drive circuitry for providing actuator drive signals individually through a pair of electrodes for each actuator, each of which has two on one pair of electrodes An inkjet printhead, characterized in that all of the unitary planar structures have thermal actuators having elongated heater elements extending between the contacts of the same. The method of claim 6, And a trench etched by the drive circuit between the electrodes. The method of claim 1, Each ink chamber has a plurality of nozzles; And the actuator, during use, simultaneously sprays ink through all the nozzles of the chamber. The method of claim 8, Inkjet printheads, each ink chamber having two nozzles. The method of claim 8, And the nozzles of each chamber are mounted in a line parallel to the length of the heater member with the central axis of the nozzles regularly spaced along the heat member. The method of claim 8, And the nozzles are elliptical. The method of claim 11, An inkjet printhead, wherein the major axes of the elliptical nozzles are aligned. The method of claim 5, The drive circuit has a drive field effect transistor (FET) for each thermal actuator, the drive voltage of the drive FET being less than 5 volts. The method of claim 13, An inkjet printhead, characterized in that the drive voltage of the drive FET is 2.5 volts. The method of claim 3, And an ink conduit in fluid communication with the openings of the plurality of ink chambers between the nozzle plate and the underlying wafer. The method of claim 15, A plurality of ink inlets formed in the wafer substrate; Wherein each ink conduit is in fluid communication with at least one of the ink inlets for receiving and supplying ink to the ink chamber. The method of claim 16, An inkjet printhead, wherein each ink conduit is in fluid communication with two ink inlets. The method of claim 15, Each ink inlet has an ink permeable trap and an outlet sized such that the surface tension of the ink meniscus across the vent prevents leakage of ink; An ink-permeable trap is directed to an outlet through which gas bubbles are discharged to the atmosphere during use. The method of claim 15, Ink chambers have an elongate shape such that the two sidewalls are longer than the other sidewalls, and an inkjet print having an opening on one of the long sidewalls to allow ink to refill the chamber. head. The method of claim 1, And the nozzles are arranged in rows such that the nozzle centers are collinear and the nozzle pitch along each row is greater than 1000 nozzles per inch.

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