KR20130141499A - Inkjet printhead having common conductive track on nozzle plate - Google Patents

Abstract

A substrate comprising a drive circuit layer; A plurality of nozzle assemblies disposed on the top surface of the substrate and arranged in one or more nozzle rows extending longitudinally along the printhead; A nozzle plate extending across the printhead; And a conductive track disposed on the nozzle plate extending parallel to the nozzle rows in the longitudinal direction along the printhead. The conductive track is connected to the common reference plane of the drive circuit layer through a plurality of conductive pillars extending between the drive circuit layer and the conductive track.

Description

Inkjet printheads with a common conductive track on the nozzle plate {INKJET PRINTHEAD HAVING COMMON CONDUCTIVE TRACK ON NOZZLE PLATE}

The present invention relates to the field of printers, in particular inkjet printheads. The present invention has been developed primarily to improve print quality and printhead performance in high resolution printheads.

Many other types of printing devices have been invented, most of which are currently in use. Known types of printing apparatuses are equipped with various methods for displaying a print medium through an associated display medium. Commonly used types of printing devices include offset presses, laser printing and copying devices, dot matrix type impact printers, thermal transfer printers, film recorders, thermal wax printers, variable descending and continuous flow type sublimation printers and ink jet printers. Etc. Each type of printer has its advantages and problems in terms of cost, speed, quality, reliability, structure and simplicity of operation.

In recent years, the field of inkjet printing, in which each individual ink pixel is obtained from one or more ink nozzles, has attracted much attention due to its inexpensive and diverse uses.

Various techniques have been invented with regard to inkjet printing. As a reference for research in this field, edited by R Dubeck and S Sherr, Output Hard Copy Devices, J. (1988), pages 207-220. There is a paper by J Moore entitled "Non-impact Printing: An Introduction and Historical Perspectives."

There are many different types of inkjet printers themselves. The use of a continuous flow of ink in inkjet printing dates back to at least 1929, and Hansell, US Patent No. 1941001 of 1929 discloses a simple form of continuous flow capacitive inkjet printing.

Sweet, US Patent No. 3596275, also discloses a continuous inkjet printing method, which includes adjusting the inkjet flow through an electro-static field such that droplets separate. This technology is still in use by several manufacturers, including Elmjet and Scitex (see also US Pat. No. 3373437 to Sweet et al.).

Piezoelectric inkjet printers are also a form of commonly used inkjet printing apparatus. Piezoelectric systems are described in US Pat. No. 39,463,98 (1970) to Kyser et al. Using diaphragm type operation, and US Patent No. 3683212 (1970) to Zolten, which initiates the operation of piezoelectric crystals in squeeze type. Of U.S. Patent No. 3747120 (1972) of Stemme, which initiates a curved piezoelectric operation, of U.S. Patent No. 4459601 of Howkins, which initiates operation of a piezoelectric propulsion type of inkjet flow. US Pat. No. 4,458,90 to Fischbeck, which discloses shear type types.

 Recently, thermal transfer inkjet printing has become a very popular inkjet printing. This inkjet printing technique includes those disclosed in British Patent No. 2007162 (1979) to Endo et al. And US Patent No. 4490728 to Vaught et al. These two references disclose an inkjet printing technique that relies on the operation of an electrothermal actuator, which creates bubbles in a narrow space, such as a nozzle, to cause ink to be ejected from a hole connected to a confined space to an associated print medium. Printing devices using electrothermal actuators are manufactured by manufacturers such as Canon and Hewlett Packard.

As can be seen from the foregoing, many different types of printing techniques can be used. Ideally, the printing technique should have many desirable attributes. These include low cost fabrication and operation, high speed operation, safe and continuous long term operation, and the like. Each technology has advantages and problems in terms of cost, speed, quality, reliability, power consumption, manufacturing simplicity, durability and consumables.

Applicant has disclosed a number of pagewidth printhead configurations. Fixed pagewidth printheads that extend across the width of the page present numerous unique design requirements compared to more conventional transverse inkjet printheads. For example, a pagewidth printhead typically consists of a plurality of individual printhead integrated circuits (ICs), which must be seamlessly connected to each other to provide high print quality. The present applicant has so far described a printhead with a separate nozzle section that enables nozzle rows to seamlessly print between printhead integrated circuits over a page width (US Pat. Nos. 7,390,071 and 7,290,852). (See references in the text). Other approaches to pagewidth printing (for example, HP Edgeline ^™ technology) employ cross-aligned printhead modules, which inevitably increase the size of the print area and provide media feed to maintain proper alignment with the print area. Requires further action. It would be desirable to provide alternative nozzle configurations that would enable new approaches to the fabrication of pagewidth printheads.

Typically, a pagewidth printhead includes 'extra' nozzle rows, which can be used to compensate for improper nozzles or to adjust the maximum power requirement of the printhead (see US Pat. Nos. 7,465,017 and 7,252,353, These contents are incorporated herein by reference). Disable nozzle compensation is a particular problem in fixed pagewidth printheads, as opposed to transverse printheads, because the media substrate makes only a single path of each nozzle of the printhead at print time.

Since redundancy inevitably increases the cost and complexity of the pagewidth printhead, it is an object of the present invention to provide a suitable mechanism for compensating for dead nozzles while minimizing redundant nozzle row (s).

It is another object of the present invention to provide a pagewidth printhead for more versatile uses, for example, capable of controlling droplet placement and / or dot resolution.

It is another object of the present invention to provide a printhead in which the MEMS and CMOS layers are integrated in different ways. It is particularly desirable to minimize the undesirable 'ground bounce' phenomenon to improve the overall electrical efficiency of the printhead.

In a first aspect, an inkjet nozzle assembly is provided,

The inkjet nozzle assembly comprises a nozzle chamber for receiving ink; And a plurality of movable paddles defining at least a portion of the cover,

The nozzle chamber includes a lid having a bottom and a nozzle hole defined at the bottom, the plurality of paddles can be operated to eject ink droplets from the nozzle hole, each paddle having a thermal bend actuator,

The column bend actuator includes: an upper thermoelastic beam coupled to a drive circuit; And

When the current flows through the thermoelastic beam, the thermoelastic beam includes a lower passive beam that is deposited on the thermoelastic beam such that it expands relative to the passive beam and each paddle bends towards the bottom of the nozzle chamber,

Each actuator can be independently controlled through each drive circuit so that the direction of the droplets ejected from the nozzle holes can be controlled by independent movement of each paddle.

As used herein, the terms "nozzle assembly" and "nozzle" are used interchangeably. Thus, "nozzle assembly" or "nozzle" refers to an apparatus for ejecting droplets in accordance with operation. A "nozzle assembly" or "nozzle" typically includes a nozzle chamber having a nozzle hole and at least one actuator.

Optionally, the nozzle assembly is disposed on the substrate, where the passivation layer of the substrate defines the bottom of the nozzle chamber.

Optionally, the lid is spaced apart from the bottom and sidewalls extend between the lid and the bottom to define the nozzle chamber.

Optionally, the nozzle assembly includes a pair of paddles facing each other located on either side of the nozzle aperture.

Optionally, the nozzle assembly includes two pairs of paddles positioned to face each other with respect to the nozzle aperture.

Optionally, the paddle is movable relative to the nozzle hole.

Optionally, each paddle defines a portion of the nozzle hole such that the nozzle hole and the paddle are movable relative to the floor.

Optionally, the thermoelastic beam is composed of a vanadium-aluminum alloy.

Optionally, the passive beam is comprised of at least one material selected from the group consisting of silicon oxide, silicon nitride, and silicon oxynitride.

Optionally, the passive beam comprises a first upper passive beam comprised of silicon oxide and a second lower passive beam comprised of silicon nitride.

Optionally, the lid is coated with a polymeric material. The polymeric material may be configured to provide a mechanical seal between each paddle and the fixing of the lid, thus minimizing ink leakage during operation of the paddle. Alternatively, the polymeric material may have holes defined in itself such that a fluid seal is provided between each paddle and the securing portion of the lid.

Optionally, the polymeric material consists of siloxane polymers.

Optionally, the siloxane polymer is selected from the group consisting of polysilsesquioxanes and polydimethylsiloxanes.

Optionally, the actuators control the timing of the drive signal for each actuator, control the strength of the drive signal for each actuator, or control both, such that coordinated movement of the plurality of paddles is provided. Can be controlled independently.

Optionally, the strength of the drive signal is controlled by the voltage of the drive signal, or the pulse width of the drive signal, or both.

In another aspect related to the first aspect, an inkjet printhead integrated circuit is provided,

An inkjet printhead integrated circuit includes a substrate including a drive circuit; And a plurality of inkjet nozzle assemblies disposed on the substrate,

Each inkjet nozzle assembly includes a nozzle chamber for receiving ink; And a plurality of movable paddles defining at least a portion of the cover,

The nozzle chamber includes a lid having a bottom defined by the top surface of the substrate and a nozzle hole defined therein, wherein the plurality of paddles can be operated to eject ink droplets from the nozzle hole, each paddle operating a thermal bend actuator. Equipped,

The column bend actuator includes: an upper thermoelastic beam coupled to a drive circuit; And

When the current flows through the thermoelastic beam, the thermoelastic beam includes a lower passive beam that is deposited on the thermoelastic beam such that it expands relative to the passive beam and each paddle bends towards the bottom of the nozzle chamber,

Each actuator can be independently controlled through each drive circuit so that the direction of the droplets ejected from the nozzle holes can be controlled by independent movement of each paddle.

Optionally, the upper surface of the substrate is defined by a passivation layer, the passivation layer being disposed in the driver circuit layer.

In a second aspect, there is provided a fixed pagewidth inkjet printhead consisting of a plurality of printhead integrated circuits connected end to end across a page width, the printhead comprising one or more nozzle rows extending along the longitudinal axis of the printhead. And each nozzle row includes repair nozzles, one or more of the nozzles being configured to eject ink droplets to a plurality of predetermined different dot positions, respectively, along the longitudinal axis.

Optionally, the one or more nozzles may be configured to eject ink droplets at two, three, four, five, six or seven different dot positions along the longitudinal axis, respectively.

Optionally, each nozzle may be configured to spray ink droplets at a plurality of predetermined different dot positions within a two-dimensional zone having a predetermined dimension.

Optionally, the zone is substantially circular or substantially elliptical, with the center of the zone corresponding to the center of the nozzle.

Optionally, the one or more nozzles may be configured to spray ink droplets toward the base dot position and at least one second dot position on either side of the base dot position.

Optionally, each nozzle in the first group is configured to inject ink droplets into a plurality of predetermined different dot positions along a longitudinal axis, wherein each nozzle in the first group includes two of the disabled nozzles in the printhead. Located within nozzle pitches, one nozzle pitch is defined as the minimum longitudinal distance between a pair of nozzles in the same nozzle row.

Optionally, each nozzle in one nozzle row is configured to eject ink droplets to a plurality of predetermined different dot positions along the longitudinal axis such that the printed dot density is greater than the nozzle density of the printhead.

Optionally, each pair of adjacent printhead integrated circuits defines a connection area, the nozzle pitch spanning the connection area is greater than one nozzle pitch, and one nozzle pitch is between a pair of nozzles in the same nozzle row. It is defined as the minimum longitudinal distance.

Optionally, each nozzle in the second group is configured to eject ink droplets to a plurality of predetermined different dot positions along the longitudinal axis, wherein the predetermined plurality of different dot positions are at least one dot position in the connection area. It includes.

In a third aspect, there is provided a fixed pagewidth inkjet printhead comprising one or more nozzle rows extending along a longitudinal axis of the printhead, each nozzle having ink liquid at a plurality of predetermined different dot positions along the longitudinal axis. It is configured to eject the enemy so that the printed dot density is larger than the nozzle density of the printhead.

Optionally, each nozzle may be configured to eject ink droplets at two, three, four, five, six or seven different dot positions along the longitudinal axis.

Optionally, each nozzle may be configured to eject ink droplets to a plurality of predetermined different dot positions along the transverse axis of the printhead.

Optionally, the printed dot density is at least twice the nozzle density of the printhead.

Optionally, each nozzle is configured to eject more than once within one line pass time, where one line pass time is defined as the time it takes for the print media to pass the printhead through one line.

In a fourth aspect, there is provided a fixed pagewidth inkjet printhead comprising one or more nozzle rows extending along a longitudinal axis of the printhead, each nozzle having ink liquid at a plurality of predetermined different dot positions along the longitudinal axis. Can be configured to spray an enemy, each nozzle having a default dot position associated with the nozzle, the printhead being configured to compensate for the failed nozzle through printing by selected normally operated nozzles located in the same nozzle row as the disabled nozzle, The selected normally operated nozzle is configured to spray at least some ink droplets at the basic dot position associated with the disabled nozzle and to spray at least some ink droplets at their basic dot position.

Optionally, the selected normally operated nozzle is positioned one, two, three or four nozzle pitches away from the disabled nozzle, where one nozzle pitch is defined as the minimum longitudinal distance between a pair of nozzles in the same nozzle row. do.

Optionally, the printhead comprises: identifying a failed nozzle; Selecting a normal operating nozzle to compensate for a failed nozzle; And configuring the selected normally operated nozzle to spray at least some of the ink droplets at the basic dot position associated with the disabled nozzle.

Optionally, the selected normally operated nozzle is configured to spray the first ink droplet at the primary dot position associated with the non-capable nozzle within one line passage time period and to spray the second ink droplet at its primary dot position, and to pass the one line through Time is defined as the time it takes for the print media to pass one line through the printhead.

Optionally, each nozzle may be further configured to eject ink droplets to a plurality of predetermined different dot positions along the transverse axis of the printhead.

Optionally, the selected normal operating nozzle ejects the first ink droplet at the primary dot position associated with the non-capable nozzle and the second ink droplet at its basic dot position within a period of one line pass time greater than five lines pass time. It is configured to.

Optionally, each droplet ejection perpendicular to the ink ejection surface of the printhead causes the droplet to reach each basic dot position.

Optionally, the printhead is configured to compensate the plurality of dead nozzles by printing the corresponding selected plurality of normally operated nozzles.

Optionally, the printhead does not have extra nozzle rows.

In another aspect related to the fourth aspect, a printhead integrated circuit for a fixed pagewidth inkjet printhead is provided, the printhead integrated circuit including one or more nozzle rows extending along the longitudinal axis of the printhead integrated circuit, each The nozzle is configured to eject ink droplets to a plurality of predetermined different dot positions along the longitudinal axis, each nozzle having a default dot position associated with the nozzle, and the printhead integrated circuit is selected in the same nozzle row as the disabled nozzle. And configured to compensate for the failed nozzle by printing of the normally operated nozzle, wherein the selected normally operated nozzle sprays at least some ink droplets at the basic dot position associated with the disabled nozzle and at least some ink droplets at its basic dot position. It is composed.

In a fifth aspect, there is provided a fixed pagewidth inkjet printhead comprising one or more rows of nozzles extending along the longitudinal axis of the printhead, the printhead having first and second ends facing each other over the pagewidth. Consisting of a plurality of printhead modules, each pair of adjoining modules of the printhead define a common connection area, the nozzle pitch spanning the connection area being greater than one nozzle pitch, and one nozzle pitch being the same A minimum longitudinal distance between a pair of nozzles in a nozzle row, wherein at least one first nozzle located at the first end of the first printhead module in a pair of adjoining modules is configured to spray ink droplets onto each connection area. do.

Optionally, the at least one second nozzle located at the second end of the second printhead module in the contacted module pair is configured to eject ink droplets to each connection area, such that the first and first facing ones of the printhead modules abut each other. The first and second nozzles at the two ends are configured to eject ink droplets into the common connection area.

Optionally, each first nozzle is configured to spray ink droplets to a plurality of predetermined different dot positions along a longitudinal axis, the predetermined plurality of different dot positions including at least one dot position in the connection region. do.

Optionally, each of the first and second nozzles is configured to spray each ink droplet at each of a plurality of predetermined different dot positions along the longitudinal axis, wherein each of the plurality of predetermined different dot positions are connected At least one dot position in the area is included.

Optionally, one dot pitch in the connection area is substantially equal to one nozzle pitch.

Optionally, each of the first and second nozzles is configured to eject more than once within one line pass time period, where one line pass time is the time it takes for the print media to pass the printhead through one line. Is defined.

Optionally, the nozzles located toward the first end are configured to eject ink droplets in a direction inclined toward the first end, and the nozzles located toward the second end are adapted to eject ink droplets in a tilted direction toward the second end. It is composed.

Optionally, the angle of inclination depends on the distance each nozzle is away from the center of each printhead module such that nozzles located closer to the center eject ink droplets in a direction that is less inclined than nozzles located farther from the center.

Optionally, the average dot pitch is greater than one nozzle pitch.

Optionally, the average dot pitch is greater than 1% greater than one nozzle pitch.

Optionally, each nozzle of the printhead is configured to eject ink droplets only at one dot position, unless compensating for an ineffective nozzle.

In a sixth aspect, a printhead integrated circuit (IC) is provided that includes one or more nozzle rows that extend along the longitudinal axis of the integrated circuit, the printhead IC being in communication with other printhead ICs to define a pagewidth printhead. Having first and second ends joined to each other, each nozzle having a basic dot position associated with the nozzle, wherein at least one first nozzle located at the first end is at least partially in a direction inclined toward the first end; And eject ink droplets of the ink droplets, and at least some of the ink droplets at their basic dot positions.

Optionally, the at least one second nozzle located at the second end is configured to eject at least some ink droplets in a direction inclined toward the second end, and also to eject at least some ink droplets at their basic dot position. .

Optionally, the first nozzle is configured to spray one ink droplet in the inclined direction toward the first end within a period of one line passage time or less and to spray one ink droplet at its own basic dot position, 1 One line pass time is defined as the time it takes for the print media to pass one line through the printhead IC.

Optionally, each second nozzle is configured to spray one ink droplet in the inclined direction toward the second end within a period of one line passage time or less and to spray one ink droplet at its own basic dot position. .

Optionally, the nozzle pitch of the printhead IC is equal to the dot pitch of printed dots, the nozzle pitch of the printhead IC is defined as the longitudinal distance between a pair of nozzles in the same nozzle row, the dot pitch being the same print line It is defined as the longitudinal distance between a pair of dots at.

Optionally, the first nozzle is configured to eject at least some of the ink droplets in a direction inclined by a distance of 1 to 3 nozzle pitches toward the first end.

Optionally, each nozzle row extends between a first connecting region at the first end and a second connecting region at the second end.

Optionally, the first and second connection regions have a width defined by a minimum distance between the edge of the printhead IC and the nozzle.

Optionally, the first connection region has a width of 0.5 to 3.5 nozzle pitch and the second connection region has a width of 0.5 to 3.5 nozzle pitch.

Optionally, the printable area of the at least one nozzle row is longer than the longitudinal range of the nozzle row when the printhead IC is stationary.

In a seventh aspect, a printhead integrated circuit (IC) for a fixed pagewidth printhead is provided, the printhead IC including at least one nozzle row extending along the longitudinal axis of the integrated circuit, the printing corresponding to the nozzle row. The length of the possible area is longer than the length of the nozzle row.

Optionally, the length of the printable area is at least one nozzle pitch longer than the length of the nozzle row, where one nozzle pitch is defined as the minimum longitudinal distance between a pair of nozzles in the nozzle row.

Optionally, the printable area is eight nozzle pitches longer than the nozzle row.

Optionally, the printable area corresponds to a line of dots printed by the nozzle row.

Optionally, the printhead includes a plurality of nozzle rows, the length of the printable area corresponding to each nozzle row being longer than the length of each nozzle row.

Optionally, the printable area extends beyond each end of the nozzle row.

Optionally, the at least one first nozzle located at the first end of the printhead IC is configured to eject ink droplets in an inclined direction toward the first end.

Optionally, the angle of inclination is such that each nozzle at the first end is spaced such that nozzles located closer to the first end eject ink droplets in a direction that is more inclined toward the first end than nozzles located farther from the first end. It depends on the distance.

Optionally, the at least one second nozzle located at the second opposite end of the printhead IC is configured to eject ink droplets in a direction inclined toward the second end.

Optionally, the inclination angle depends on the distance each nozzle is away from the center of the printhead IC such that nozzles located closer to the center eject ink droplets in a direction that is less inclined than nozzles farther from the center.

Optionally, the nozzles located in the central region of the printhead IC are configured to eject ink droplets in a direction substantially perpendicular to the ink ejection surface of the printhead IC.

Optionally, the average dot pitch of the printable area is greater than one nozzle pitch.

Optionally, the average dot pitch is greater than 1% greater than one nozzle pitch.

Optionally, each nozzle of the printhead is configured to eject ink droplets only at one dot position, unless compensating for an ineffective nozzle.

In an eighth aspect, a method of controlling the direction of ejecting ink droplets from an inkjet nozzle is provided, wherein the inkjet nozzle includes a nozzle chamber having a lid having a nozzle hole defined therein and a plurality of movable paddles defining at least a portion of the lid. Each paddle includes a thermal bend actuator, the method comprising:

Operating a first thermal bend actuator through each first drive circuit such that each first paddle flexes toward the bottom of the nozzle chamber;

Operating a second row bend actuator through each second drive circuit such that each second paddle flexes toward the bottom of the nozzle chamber; And

Thereby ejecting ink droplets from the nozzle apertures,

The operation of the first and second row bend actuators is independently controlled by the first and second drive circuits to control the direction of the droplets ejected from the nozzle holes.

Optionally, the first and second actuators control the timing of the drive signal for each of the first and second actuators so that coordinated movement of the plurality of paddles is provided, or asymmetrical movement of the plurality of paddles occurs. It is controlled independently by controlling the strength of the drive signal for each actuator, or by controlling both.

Optionally, the first actuator is operated prior to the second actuator to eject the droplet in the first direction or the second actuator is operated prior to the first actuator to eject the droplet in the second direction.

Optionally, the first actuator is supplied with more power than the second actuator or the second actuator is supplied with more power than the first actuator.

Optionally, the strength of the drive signals is based on the voltage of the drive signals; And the pulse width of the drive signals.

Optionally, the two pairs of paddles are positioned to face each other with respect to the nozzle hole.

Optionally, the method of the present invention is:

Operating a third row bend actuator through each first drive circuit such that each third paddle flexes toward the bottom of the nozzle chamber;

Operating a fourth row bend actuator through each second drive circuit such that each second paddle flexes toward the bottom of the nozzle chamber,

The operation of the first, second, third and fourth row bend actuators is individually controlled by the respective first, second, third and fourth drive circuits so that the direction of the droplets ejected from the nozzle holes is controlled.

Optionally, the paddle is movable relative to the nozzle hole.

Optionally, each paddle defines a portion of the nozzle hole such that the nozzle hole and the paddle can move relative to the bottom of the nozzle chamber.

In a ninth aspect, a method is provided for compensating for a failed nozzle of a fixed pagewidth printhead, the printhead having one or more rows of nozzles extending along the longitudinal axis of the printhead, each nozzle being predetermined along the longitudinal axis. A plurality of thermal bend actuating paddles that can be configured to eject ink droplets to a plurality of different dot positions, each nozzle having a default dot position associated with the nozzle, the method comprising:

Identifying an ineffective nozzle;

Selecting a normal operating nozzle in the same nozzle row as the disabled nozzle; And

Spraying at least a portion of the ink droplets from the selected normally operated nozzle to a basic dot location associated with the disabled nozzle.

Optionally, the method further comprises spraying at least some of the ink droplets from their selected normal operating nozzle to their basic dot position.

Optionally, the selected normally operated nozzle is positioned one, two, three or four nozzle pitches away from the disabled nozzle, and one nozzle pitch is defined as the minimum longitudinal distance between a pair of nozzles in the same nozzle row. do.

Optionally, the method of the present invention is:

Advancing the print media by one line to transversely pass through the stationary printhead within a period of one line pass time;

Ejecting a first ink droplet from a selected normally operated nozzle to a basic dot position associated with the disabled nozzle; And

Spraying a second ink droplet at its default dot position from the selected normal operating nozzle,

The selected normal operating nozzle ejects the first and second ink droplets within a period of one line passage time.

Optionally, the selected normally operated nozzle ejects the first and second ink droplets in any order.

Optionally, each nozzle may be configured to eject ink droplets at a plurality of predetermined different dot positions along the transverse axis of the printhead.

Optionally, the method of the present invention is:

Advancing the print media one line per line pass time to pass through the stationary printhead in a transverse direction;

Ejecting a first ink droplet from a selected normally operated nozzle to a basic dot position associated with the disabled nozzle; And

Spraying a second ink droplet at its default dot position from the selected normal operating nozzle,

The selected normal working nozzle ejects the first and second ink droplets within a period of pass time over one line and less than five lines.

Optionally, the disabled nozzle is identified by detecting the electrical resistance of the one or more actuators corresponding to the disabled nozzle.

In a tenth aspect, a method is provided for printing at a dot density that exceeds the nozzle density of a fixed pagewidth printhead configured by connecting a plurality of printhead integrated circuits across one another across the pagewidth, the printhead being a type of printhead. And at least one row of nozzles extending in the direction, the method comprising:

Advancing the print media by one line every one line passing time to cross the fixed printhead in a transverse direction;

Spraying ink droplets from predetermined nozzles in a nozzle row such that continuous print lines are produced,

At least some of the predetermined nozzles spray ink droplets for one line passing time at a plurality of predetermined different dot positions along the longitudinal axis, respectively, such that the printed dot density of each printed line is greater than the nozzle density. .

In an eleventh aspect, an inkjet printhead is provided, the inkjet printhead:

A substrate comprising a drive circuit layer;

A nozzle chamber disposed on the top surface of the substrate and arranged in one or more nozzle rows extending longitudinally along the printhead, each having a bottom defined on the top surface, a cover spaced from the bottom, and a nozzle hole defined on the cover A plurality of nozzle assemblies comprising an actuator for ejecting ink from the nozzle;

A nozzle plate extending across the printhead and at least partially defining the lids; And

At least one conductive track extending longitudinally along the printhead parallel to the nozzle rows and disposed on the nozzle plate,

The conductive track is connected to a common reference plane in the drive circuit layer through a plurality of conductive pillars extending between the drive circuit layer and the conductive track.

Optionally, the common reference plane defines a ground plane or a power plane.

Optionally, the printhead comprises at least one first conductive track, the first conductive track being directly connected to a plurality of actuators in at least one nozzle row adjacent to the first conductive track.

Optionally, the printhead further comprises at least one second conductive track, wherein the second conductive track is not directly connected with any actuators.

Optionally, the first conductive track extends continuously along the printhead to provide a common reference plane for each actuator in the nozzle row.

Optionally, the first conductive track extends discontinuously along the printhead to provide a common reference plane for the group of actuators in the nozzle row.

Optionally, a first conductive track is located between the nozzle rows of each pair of nozzle rows, and the first conductive track provides a common reference plane for the plurality of actuators in the two nozzle rows of the pair.

Optionally, each actuator has a first terminal connected directly to the first conductive track and a second terminal connected to a drive transistor in the drive circuit layer.

Optionally, each cover comprises at least one actuator, the first terminal of each actuator being connected to the first conductive track via transverse connectors extending transversely across the nozzle plate with respect to the first conductive track.

Optionally, the second terminal is connected to the drive transistor through an actuator column extending between the drive circuit layer and the second terminal.

Optionally, the actuator pillars are perpendicular to the plane of the first conductive track.

Optionally, each cover comprises at least one movable paddle comprising each thermal bend actuator, the paddle being movable towards the bottom of each nozzle chamber such that ink is ejected from the nozzle holes, the thermal bend actuator being:

An upper thermoelastic beam having first and second terminals; And

When the current flows through the thermoelastic beam, the thermoelastic beam includes a lower passive beam that is deposited on the thermoelastic beam such that it expands relative to the passive beam and each paddle bends towards the bottom of the nozzle chamber.

Optionally, the thermoelastic beam lies coplanar with the conductive track.

Optionally, the thermoelastic beam and the conductive track are made of the same material.

Optionally, the nozzle plate is made of ceramic material.

Optionally, the drive circuit layer includes drive field effect transistors (FETs) for each actuator, each drive FET having a gate for receiving logic injection signals, a source electrically connected to the power plane, and an electrically connected ground plane. The drain being driven, the drive FET being:

A pFET with an actuator connected between the drain and the ground plane; or

The actuator is one of the nFETs connected between the power plane and the source.

Optionally, the drive FET is a pFET, the first conductive track provides a ground plane, and the first terminal of the actuator is connected to the first conductive track and the second terminal of the actuator is connected to the drain of the pFET.

Optionally, the second conductive track provides a power plane and is connected to the source of the pFET.

Optionally, the drive FET is an nFET, the first conductive track provides a power plane, and the first terminal of the actuator is connected to the first conductive track and the second terminal of the actuator is connected to the source of the nFET.

Optionally, the second conductive track provides a ground plane and is connected to the drain of the nFET.

In a twelfth aspect, a printhead integrated circuit (IC) for an inkjet printhead is provided, the printhead integrated circuit:

A substrate comprising a drive circuit layer;

A nozzle chamber disposed on the top surface of the substrate and arranged in one or more nozzle rows extending longitudinally along the printhead IC, each having a bottom defined on the top surface, a lid spaced from the bottom, and a nozzle defined on the lid A plurality of nozzle assemblies comprising an actuator for ejecting ink from the aperture;

A nozzle plate extending across the printhead IC and at least partially defining the covers; And

At least one conductive track extending longitudinally along the printhead parallel to the nozzle rows and deposited on the nozzle plate,

The conductive track is connected to a common reference plane in the drive circuit layer through a plurality of conductive pillars extending between the drive circuit layer and the conductive track.

Optionally, the common reference plane defines a ground plane or a power plane.

Optionally, the conductive track is disposed above or below the nozzle plate.

Alternative embodiments of the invention will now be described with reference to the accompanying drawings as an example.
1 is a side cross-sectional view of an inkjet nozzle assembly partially fabricated after the first process of steps in which nozzle chamber sidewalls are formed;
FIG. 2 is a perspective view of the partially fabricated inkjet nozzle assembly shown in FIG. 4; FIG.
3 is a side sectional view of an inkjet nozzle assembly partially fabricated after the second process of steps in which the nozzle chamber is filled with polyimide;
4 is a perspective view of the partially fabricated inkjet nozzle assembly shown in FIG. 3;
5 is a side sectional view of an inkjet nozzle assembly partially fabricated after the third process of the steps in which the connecting pillars are formed up to the lid of the chamber;
FIG. 6 is a perspective view of the partially fabricated inkjet nozzle assembly shown in FIG. 5;
7 is a side sectional view of an inkjet nozzle assembly partially fabricated after the fourth process of the steps of forming conductive metal plates;
FIG. 8 is a perspective view of the partially fabricated inkjet nozzle assembly shown in FIG. 7; FIG.
9 is a side cross-sectional view of an inkjet nozzle assembly partially fabricated after the fifth process of forming the active beam of the heat bend actuator;
FIG. 10 is a perspective view of the partially fabricated inkjet nozzle assembly shown in FIG. 9;
FIG. 11 is a side cross-sectional view of an inkjet nozzle assembly partially fabricated after the sixth process of forming the moving lid portion including the heat bend actuator; FIG.
12 is a perspective view of the partially fabricated inkjet nozzle assembly shown in FIG. 11;
FIG. 13 is a side cross-sectional view of an inkjet nozzle assembly partially fabricated after the seventh process of steps in which a hydrophobic polymer layer is deposited and a photosensitive pattern is formed;
FIG. 14 is a perspective view of the partially fabricated inkjet nozzle assembly shown in FIG. 13;
15 is a side cross-sectional view of a fully formed inkjet nozzle assembly;
FIG. 16 is a cutaway perspective view of the inkjet nozzle assembly shown in FIG. 15; FIG.
17 is a plan view of an inkjet nozzle having movable cover paddles and movable nozzle holes facing each other;
18 is a top view of an inkjet nozzle with facing paddles facing each other that can be moved relative to a stationary nozzle hole;
FIG. 19 is a circuit schematic for individually controlling two actuators of the inkjet nozzle shown in FIG. 17; FIG.
20 is a plan view of a portion of a printhead including inkjet nozzles with four movable cover paddles;
FIG. 21 shows a two-dimensional printable area of one of the inkjet nozzles shown in FIG. 20;
22 is a side view of a portion of an inkjet printhead configured such that the printed dot density is greater than the nozzle density of the printhead;
23 is a side view of a portion of an inkjet printhead configured for invalid nozzle compensation;
24 is a plan view of an inkjet printhead constructed by connecting five printhead integrated circuits (IC);
25 is a top view of an individual printhead IC;
FIG. 26 is a perspective view of the distal region of the printhead IC shown in FIG. 25;
FIG. 27 is a perspective view showing a connection area between a pair of printhead ICs as shown in FIG. 25;
28 is a perspective view showing a connection area of a pair of printhead ICs including nozzles configured to be able to print on the connection area;
29 is a side view of a printhead IC with a printable area longer than its corresponding row of nozzles;
30 is a side view of a printhead IC configured to allow end nozzles to print to each connection area;
31 is a top view of a portion of a printhead IC having conductive tracks disposed on the nozzle plate;
32 is a circuit schematic of an actuator connected to a drive pFET.
33 is a circuit schematic of an actuator connected to a drive nFET.
34 is a top view of a portion of another form of printhead IC with conductive tracks disposed on the nozzle plate.

Including operation cover paddle Inkjet  Fabrication Process of Nozzle Assembly

For completeness and through the background, a process of making an inkjet nozzle assembly (or “nozzle”) comprising a movable cover paddle with a thermal bend actuator will now be described. The complete inkjet nozzle assembly 100 shown in FIGS. 15 and 16 utilizes a thermal bend actuator, where the movable paddle 4 of the nozzle chamber cover is bent toward the substrate 1 to discharge ink. This manufacturing process is described in the applicant's previous US patent publications US 2008/0309728 and US 2008/0225077, the contents of which are incorporated herein by reference. However, it will be appreciated that the corresponding fabrication processes can be used to fabricate any of the inkjet nozzle assemblies described herein, in fact printheads and printhead integrated circuits (ICs).

The starting point for MEMS fabrication is a standard CMOS wafer with CMOS drive circuitry disposed on the top layer (s) of the silicon wafer subjected to surface deactivation. At the end of the MEMS fabrication process, the wafer is separated into individual printhead integrated circuits (ICs), each IC comprising one CMOS driver circuit layer and a plurality of nozzle assemblies.

In the process of the steps shown in FIGS. 1 and 2, an 8 micron silicon dioxide layer is first deposited on the upper surface of the substrate 1. The depth of silicon dioxide defines the depth of the nozzle chamber 5 of the ink jet nozzle. After depositing the silicon dioxide (SiO ₂ ) layer, the silicon dioxide layer is etched to define the walls 4, which will form the sidewalls of the nozzle chamber 5 shown very clearly in FIG. 2. .

3 and 4, the nozzle chamber 5 is then filled with a photoresist or polyimide 6, which serves as a sacrificial support layer for subsequent deposition steps. The polyimide 6 is fixed on the wafer using standard techniques and, after UV curing and / or heat curing, is flush with the top surface of the silicon dioxide wall 4 by a chemical mechanical planarization (CMP) process. .

In FIGS. 5 and 6, not only the lid 7 of the nozzle chamber 5 is formed, but also the highly conductive actuator pillars 8 extend downwards towards the electrodes 2. First, a 1.7 micron silicon dioxide layer is deposited on the polyimide 6 and on the wall 4. This silicon dioxide layer defines the lid 7 of the nozzle chamber 5. A pair of vias is then formed down towards the electrodes 2 using a standard anisotropic DRIE process formed in the wall 4. This etching process exposes a pair of electrodes through each via. Next, vias are then filled with a highly conductive metal, such as copper, using an electroless plating method. The copper pillars 8 thus deposited are flush with the silicon dioxide sheath 7 through a CMP process to provide a flat structure. It can be seen that the copper actuator pillars 8 formed by the electroless copper plating method provide a linear conductive path that meets each of the electrodes 2 and extends to the lid 7.

In FIGS. 7 and 8, metal pads 9 are formed by depositing and etching a 0.3 micron layer of aluminum. Any high conductive metal (eg, aluminum, titanium, etc.) may be used, but should be deposited to a thickness of about 0.5 microns or less so as not to severely compromise the overall flatness of the nozzle assembly. The metal pads 9 are defined by an etching process such that they are located in a predetermined 'curved region' of the thermoelastic active beam on the actuator pillars 8 and on the lid 7. It will of course be appreciated that the metal pads 9 are not very essential and the process of the steps shown in FIGS. 7 and 8 can be omitted in the fabrication process.

9 and 10, a thermoelastic active beam 10 is formed over the silicon dioxide sheath 7. A portion of the silicon dioxide sheath 7 is deposited on the active beam 10 to function as the lower passive beam 16 of the mechanical thermal bend actuator defined by the active beam 10 and the passive beam 16. This thermoelastic active beam 10 may be composed of any suitable thermoelastic material, such as titanium nitride, titanium nitride aluminum and aluminum alloys. The vanadium-aluminum alloy has a high coefficient of thermal expansion, a low density and a high Young's modulus, the contents of which are incorporated herein by reference and as described in the previous US patent application Ser. No. 11 / 607,976, filed December 4, 2002. Since favorable physical properties, such as (Young's Modulus), are combined, it is a preferable material.

To form the active beam 10, first a layer of 1.5 micron active beam material is deposited through a standard PECVD process. The beam material is then etched using a standard metal etching process to define the thermoelastic active beam 10. After the metal etching process is completed, as shown in FIGS. 9 and 10, the active beam 10 includes a partial nozzle hole 11 and a bent beam element 12, with each end of the bent beam element being actuator pillars. (8) is electrically connected to the power supply and the ground electrode (2). The flat beam element 12 extends from the top of the first (power) actuator column and bends approximately 180 degrees back to the top of the second (ground) actuator column.

With continued reference to FIGS. 9 and 10, the metal pads 9 are positioned so that current flows well in potentially high resistance areas. One metal pad 9 is located in the curved area of the beam element 12 and is sandwiched between the active beam 10 and the passive beam 16. The other metal pads 9 are located between the tops of the actuator pillars 8 and the ends of the beam element 12.

11 and 12, the silicon dioxide lid 7 is then etched to completely define the nozzle hole 13 and the movable cantilever paddle 14 in the lid. The paddle 14 includes a thermal bend actuator 15 consisting of a thermoelastic active beam 10 and an underlying passive beam 16. The nozzle hole 13 is defined in the paddle 14 of the cover so that the nozzle hole is moved through the actuator during operation. As described in Applicant's U.S. Patent Application Serial No. 11 / 607,976, incorporated herein by reference, configurations in which the nozzle hole 13 is fixed relative to the paddle 14 are equally possible.

Peripheral spacing or gap 17 around the movable paddle 14 separates the paddle from the fixing portion 18 of the cover. This clearance 17 causes the movable paddle 14 to bend toward the substrate 1 into the nozzle chamber 5 as the actuator 15 operates.

13 and 14, a polymer layer 19 is then deposited over the entire nozzle assembly and etched to redefine the nozzle hole 13. The polymer layer 19 is a thin, removable metal layer (not shown) prior to etching the nozzle hole 13, as described in US 2008/0225077, the contents of which are incorporated herein by reference. Can be protected.

Polymer layer 19 performs several functions. First, the polymer layer fills in the peripheral gap 17 to provide a mechanical seal between the paddle 14 and the fixing portion 18 of the lid 7. If the polymer has a sufficiently low Young's modulus, the actuator can still bend towards the substrate 1 and also prevent the ink from leaking out through the gap 17 during operation. Second, the polymer has a high hydrophobicity, which minimizes the tendency of ink to flow out of the relatively hydrophilic nozzle chambers and to bury the ink jetting surface 21 of the printhead. Third, the polymer functions as a protective layer that facilitates maintenance of the printhead.

The polymer layer 19 may be formed of polydimethylsiloxane (PDMS) or polysilsesquioxanes, as described in US Patent Application No. 12 / 508,564, the contents of which are incorporated herein by reference. It may consist of a siloxane polymer such as a polymer. Polysilsesquioxane is typically empirical formula (RSiO _{1 .5)} have a _n, where R is hydrogen or an organic group and n is an integer representing the length of the polymer chain. The organic groups may be a C _{1 -12} alkyl (e.g., methyl), C _{1 -10} aryl (e.g., phenyl) or C _{1 -16} alkyl, aryl (e. G., Benzyl). The polymer chain can be of any length known in the art (eg, n is from 2 to 10,000, 10 to 5,000 or 50 to 1,000). Specific examples of suitable polysilsesquioxanes are poly (methylsilsesquioxane) and poly (phenylsilsesquioxane).

15, 16, the ink supply passage 20 is etched through the back of the substrate 1 to the nozzle chamber 5, as shown in Figs. Although the ink supply passage 20 is shown aligned with the nozzle hole 13 in FIGS. 15 and 16, the ink supply passage may of course be located offset from the nozzle hole.

After etching for the ink supply passage, the polyimide 6 filling the nozzle chamber 5 is removed through an ashing process (front ashing or back ashing) using, for example, an oxygen plasma. Nozzle assembly 100 is provided.

A pair of operation cover facing each other Paddles  Equipped Inkjet  Nozzle assembly

As can be seen in FIG. 12, the inkjet nozzle assemblies described previously by the applicant include one movable paddle 14 for ejecting ink through the nozzle hole 13.

Referring to FIG. 17, there is schematically shown a top view of an inkjet nozzle assembly 200 comprising a pair of cover paddles 14A and 14B facing each other. The top polymer layer is shown in plan view for clarity and omitted from all the inkjet nozzles described herein. Also for convenience of description, the features common to all the inkjet nozzle assemblies described herein are given the same reference numerals.

Each paddle 14A and 14B has respective thermal bend actuators 15A and 15B defined by an upper thermoelastic beam and a lower passive beam in the same manner as the inkjet nozzle 100 described above. In addition, each column bend actuator (and thus each paddle) is independently controlled through each drive circuit in the CMOS drive circuit layer of the substrate 1. This allows the first actuator 15A (and thus the first paddle 14A) to be controlled independently of the second actuator 15B (and thus the second paddle 14B).

FIG. 17 shows nozzle assembly 200 with paddles 14A and 14B facing each other, where each paddle defines a portion of nozzle hole 13. Thus, the nozzle hole 13 will move through the paddle during operation.

18 shows another type of nozzle assembly 210 with paddles 14A and 14B facing each other, where each paddle can be moved relative to the nozzle hole 13. In other words, the nozzle hole 13 is defined in the fixed portion of the lid 7. Of course, as shown in Figures 17 and 18, it will be appreciated that both nozzle assemblies 200 and 210 are within the scope of the present invention.

FIG. 19 shows a simplified circuit diagram for controlling the relative amount of power supplied to each actuator 15A and 15B of the nozzle assembly 200. Actuator 15A receives full power while the amount of power supplied to actuator 15B is varied using potentiometer 202.

Experimental measurements using several groups of potentiometer resistance values have demonstrated that different maximum paddle speeds can be obtained by reducing the amount of power supplied to the actuator 15B. For example, with the same amount of power, the maximum paddle speeds are nearly equal to each other. However, if the resistance value of the potentiometer is increased, the maximum paddle speed of the paddle 14B is significantly reduced compared to the paddle 14A. For example, the maximum paddle speed of paddle 14B may be reduced to less than 75%, less than 50%, or less than 25% of the maximum paddle speed of paddle 14A.

The difference between these maximum paddle velocities eventually has a significant effect on the direction of the droplets. Thus, by controlling the relative amounts of power supplied to each of the actuators 15A and 15B, the direction of the droplets injected from the nozzle holes 13 can be controlled. Experimentally, the droplet direction can be tilted to about 4 dot pitch on the printed page. Thus, dot pitches of -4, -3, -2, -1, 0, +1, +2, +3, and +4 (also all non-integer dot positions between them) can be obtained in one nozzle and , Where '0' is defined as the default dot position resulting from the droplet being ejected in a direction perpendicular to the ink jetting surface. These results have a significant impact on the construction of the pagewidth inkjet printhead, as discussed in more detail below.

Of course, for experimental purposes, the use of potentiometer 202 makes it easier to determine the range of power parameters. However, inclined droplet injection can also be achieved by controlling the operating timing as an alternative to or in connection with controlling the power supplied to each actuator. For example, before or after actuator 15B receives its actuation signal, actuator 15A may receive its actuation signal, resulting in asymmetrical paddle movement and inclined liquid crystal injection.

In addition, the power supplied to each actuator can be controlled by varying the pulse width of the drive signal. Indeed, this method of changing the power supplied to each actuator may be the most appropriate method using a CMOS driving circuit, especially when it is desired to change the droplet direction 'quickly'.

4 operation covers Paddles  Equipped Inkjet  Nozzle assembly

The nozzle assemblies 200 and 210 shown in FIGS. 17 and 18 allow the droplet ejection direction to be controlled along one axis. Typically (and most usefully), this axis may be the longitudinal axis of the long pagewidth printhead from which the nozzle rows extend. However, additional control of droplet directivity can be achieved with more paddles than two paddles arranged relative to the nozzle aperture.

20 shows a portion of a printhead comprising inkjet nozzle assemblies 220, each nozzle assembly 220 having four movable paddles 14A, 14B, arranged with respect to a fixed nozzle hole 13. 14C and 14D). Attenuation pillars 221 protruding from the side wall of the nozzle chamber assist in controlling droplet injection characteristics and chamber refill, particularly in the event of one of the actuators failing.

In the four paddle arrangement shown in FIG. 20, droplet injection can be tilted along one or both axes (ie, longitudinal and transverse axes) by adjusting the movement of the four paddles. Thus, ink droplets may be ejected at any point in the two-dimensional region of the print medium, which is typically a circular or elliptical region with a spray nozzle in the center thereof.

FIG. 21 shows a portion of a nozzle row having a plurality of nozzles 220 arranged at one nozzle pitch interval along each longitudinal axis of the nozzle row. The elliptical region 222 of the print medium shows a range within which the ejection nozzle '0' located in the center of the elliptical region can eject ink droplets. As shown in FIG. 21, the spray nozzle '0' may spray to any dot position within its two-dimensional elliptical region 222.

The ability to eject ink droplets along the transverse axis (ie, perpendicular to the axis of the longitudinal nozzle row) requires that droplet ejection from the nozzle assembly 220 occur exactly simultaneously with other nozzles in the same nozzle row. Means no. Typically, all ejection nozzles of a pagewidth printhead must complete ejection within one line-time period, which is the time it takes for the print media to advance transversely through the printhead at one line interval. . However, a spray nozzle with the ability to eject ink droplets along the transverse axis of the printhead, sprays ink droplets before or after one print line passes through the nozzle and also directs the ink droplets to this same print line. It can be configured to. Thus, the nozzle assembly 220 may allow the configuration of the pagewidth printhead to have greater flexibility than the nozzle assemblies 200 and 210.

In addition, the plurality of cover paddles increases the overall spraying capacity available for each nozzle. The four paddle nozzle configuration is therefore more suitable for injecting viscous fluid than the two paddle configuration or one paddle configuration. Likewise, the two paddle nozzle configuration is more powerful than the one paddle nozzle configuration.

The capability of each individual actuator can also be increased by increasing the length of the actuator beam and / or providing a serpentine actuator beam with a plurality of bends. Twisted actuator beams are described in Applicant's US Patent No. 7,611,225, the contents of which are incorporated herein by reference. Accordingly, the present invention also provides high performance inkjet nozzles suitable for ejecting a fluid having a relatively high viscosity, for example a fluid having a higher viscosity than water.

High dot  With density Inkjet Print head

In a typical pagewidth printhead, each spray nozzle (i.e., the spray nozzle selected by the print data received at the printhead) sprays once within one line-time. In addition, each nozzle ejects ink droplets to reach the basic dot position associated with the nozzle. When the nozzle ejects toward its associated default dot position, ink droplet ejection is usually in a direction perpendicular to the ink ejection surface of the printhead. Thus, in traditional pagewidth printheads, the nozzle density of the printhead corresponds to the dot density of the printed page. For example, in the case where the nozzle pitch and the dot pitch are respectively defined as the interval between adjacent nozzles and the center of the dots, the page width nozzle column having the value of the nozzle pitch n prints a dot line having the value of the dot pitch n. something to do.

However, the inkjet nozzle assemblies 200, 210 and 220 enable the design of the printhead such that the printed dot pitch is smaller than the nozzle pitch of the printhead, so that the printed dot density exceeds the nozzle density of the printhead. do.

FIG. 22 shows a portion of pagewidth printhead 230 when the printed dot pitch is smaller than the nozzle pitch of the printhead. Three nozzles 231 in the same nozzle row are shown spaced at intervals of nozzle pitch n. Each of these nozzles may be comprised of, for example, a nozzle assembly 210 (as shown in FIG. 18). Ink droplets from each nozzle may be ejected onto the print medium 235 at a plurality of different dot positions along the longitudinal axis indicated by arrow 236. As shown in Figures 22, 23 29 and 30, the print media 235 is conveyed out of the page (i.e. toward the viewer of the drawing and in the direction across the longitudinal axis of the printhead or printhead IC).

Referring again to FIG. 22, each nozzle 231 is configured to eject ink to two different dot locations in one line pass time period—one dot location orthogonal to the printhead surface. The default dot position 232 as it is ejected, and the other dot position 234 is the result of the inclined ink ejection in which the ink droplets arrive at intermediate points between the basic dot positions. Therefore, the resulting dot pitch d becomes smaller than the nozzle pitch n such that the printed dot density exceeds the nozzle density of the printhead.

In the example shown in FIG. 22, nozzle pitch n is twice the dot pitch d, but it can be understood that the ratio of nozzle pitch n to dot pitch d can be configured to any value by the printhead such that n> d. There will be. For example, if each nozzle prints at the basic dot position and two different dot positions (for example, on both sides of the basic dot position) within one line pass time, the result is a dot pitch where n = 3d. You will be able to get

The dot pitch that can actually be obtained is limited only by the ink chamber refill rate relative to the speed at which the print media passes through the printhead. Applicants' experiments have shown that an ink chamber, at 60 prints per minute, is printed at least twice in one line pass time period so that it prints at a dot density twice the dot density obtainable by a typical fixed pagewidth printhead. Shows that it can be recharged. Of course, slowing down the print media feed rate (eg, up to 30 ppm) can yield higher dot densities.

In this way, fixed pagewidth printheads can achieve a variety of uses similar to scanning printheads. In the scanning printhead, it is understood that the printed dot density can be increased by lowering the printing speed, since the scanning printhead has the opportunity to scan across each line and print at many different dot positions depending on the scanning speed. It is well known. The fixed pagewidth printhead 230 shown in FIG. 22 has a variety of similar uses and is capable of printing at very high dot densities (eg, 3200 dpi), even at much faster speeds than known scanning printheads.

Nozzle Compensation

Applicant has previously described an apparatus for compensating for impossible nozzles in a fixed pagewidth printhead. As used herein, 'incapable nozzle' means a nozzle which does not eject ink at all, or a nozzle which ejects ink with insufficient control of droplet ejection speed or ejection direction. Normally, 'nozzles' are caused by actuator failure (which is the cause of the nozzle failure that is most easily identified through the detection circuit), but nozzle nozzles can be blocked beyond penetration or ink jetting It may also occur due to irremovable debris that blocks or partially blocks the nozzle hole.

Typically, disable nozzle compensation in a fixed pagewidth printhead requires printing of extra nozzle rows (as described in US Pat. Nos. 7,465,017 and 7,252,353, the contents of which are incorporated herein by reference). This has the disadvantage that the printhead inevitably requires extra nozzle row (s) which increases the cost of the printhead.

Alternatively, the visual effect of a dead nozzle can be compensated for by spraying (preferably 'over-output') the nozzle adjacent to the dead nozzle (described in US Pat. No. 6,575,549, the contents of which are incorporated herein by reference). As if). In practice, this requires changing the print mask to minimize the overall visual effect of the ineffective nozzle.

Inkjet nozzle assemblies 200, 210, and 220 can compensate for nozzle failure without requiring extra nozzle rows or changing the print mask. FIG. 23 shows a portion of pagewidth printhead 240 where disabled nozzles 242 are compensated for by nozzles operating adjacently in the same nozzle row.

The same nozzle row is shown as having three nozzles each consisting of a nozzle assembly 210 (as shown in FIG. 18). The intermediate nozzle 242 is disabled or otherwise malfunctioning, while adjacent nozzles 243 and 244 located on either side of the intermediate nozzle 242 are operating normally.

Ink droplets from each of the normally operating nozzles 243 and 244 are provided with a plurality of different dot positions along the longitudinal axis 236 on the print medium 235 (supplied toward the viewer as shown in FIG. 23). Can be sprayed on. The nozzle 243 ejects ink droplets to their basic dot position 247 and to the basic dot position 248 associated with the disabled nozzle 242 within one line pass time period. Thus, the nozzle 243 prints two dots in one line pass time period to compensate for an incompetent nozzle in the same nozzle row. Of course, in the next line pass time period, the nozzle 244 may compensate for the disabled nozzle 242 on behalf of the nozzle 243, allowing the nozzles 243 and 244 to share the compensation of the disabled nozzle together. do. In addition, the compensation nozzle (s) need not be immediately adjacent to the incapable nozzle depending on the inclined drop ejection angle obtained. For example, the compensating nozzle (s) can be located at -4, -3, -2, -1, 0, +1, +2, +3 or +4 nozzle pitch away from the non-capable nozzles, so that many other nozzles This can be done by dividing the compensation operation of the nozzle which cannot be inserted.

FIG. 23 illustrates a scenario where the nozzle 243 needs to spray ink droplets at its basic dot position 247 and the basic dot position 248 associated with the disabled nozzle 242 within one line pass time period. It is shown. Of course, the print mask basically indicates which nozzles are needed for spraying during the one line pass time. In the case where a non-replaceable nozzle is required by the print mask to spray during a particular one-line pass time, a normally functioning suitable nozzle will be preferentially compensated if it is not necessary to spray at its default dot position for a specific one-line pass time. You can work. Selecting compensating nozzles in this way further minimizes the need for normal operating nozzles adjacent to the ineffective nozzle. Indeed, in many cases, the print mask can prevent the case where the compensation nozzle is required to spray twice in one line pass time period.

Alternatively, the printhead comprised of nozzle assemblies 220 enables compensation of the dead nozzle without the need for the compensating nozzle to spray within one line pass time equal to the time allotted to the dead nozzle. Since the nozzle assembly 220 can spray at any dot position (including dot positions along the transverse axis of the printhead) in the two-dimensional region, compensation of the ineffective nozzle may be delayed or preceded by the next line passing time. This can be done in advance by pulling the line through time. This makes the choice of compensation nozzles and the working time more varied.

Disabled nozzles are typically identified by detecting the resistance of one or more actuators that typically correspond to the disabled nozzles. This method preferably enables identification and compensation of dynamic incapable nozzles. However, other impossible nozzle identification methods (eg, optical techniques using predetermined print patterns) are of course possible.

Connected seamlessly Page width Print head

Except for monolithic pagewidth printheads with very low wafer yields, Applicants' pagewidth printheads generally comprise a plurality of printhead ICs connected together end to end across a page width.

FIG. 24 illustrates a configuration in which five printhead ICs 251A to 251E are connected to each other to form a photo width printhead 250, while one printhead IC 251 is shown in FIG. . It will be appreciated that more printhead ICs 251 can be glued together to produce longer pagewidth printheads (eg, A4 printheads and wide printheads). Printhead ICs glued together in this way have the advantage of minimizing the width of the print zone, thus eliminating the need for very precise alignment between the print media and the printhead. However, referring to FIGS. 26 and 27, printhead ICs glued together have a disadvantage in that it is difficult to print on connection areas 257 between pairs of printhead ICs in contact with each other. The reason is that the nozzles 255 cannot be fabricated down to the end edges 258 of each printhead IC-and to the edges for structural strength and to stick the printhead ICs together. This is because a minimum 'blind spot' (259) must be maintained. Thus, the actual nozzle pitch between printhead ICs in contact with each other is inevitably larger than one nozzle pitch in the nozzle row of the printhead.

As a result, the pagewidth printhead should be designed to print dots seamlessly across the connecting areas. Referring back to FIGS. 24-27, the present applicant has described a solution to the problem of configuring a pagewidth printhead with the printhead ICs attached to each other. As best shown in FIG. 27, the separate triangular portions 253 of the nozzles effectively fill the gap between the nozzles of the printhead ICs in contact with each other. By adjusting the injection timing of the nozzles 255 in the separate triangular portion 253 (e.g., spraying these nozzles later than their corresponding nozzle rows), dots are seamlessly drawn across the connection area 257. Can be printed. The function of this separate nozzle triangle portion 253 is fully described in US Pat. Nos. 7,390,071 and 7,290,852, the contents of which are incorporated herein by reference.

FIG. 27 also shows bond pads 75 and alignment origin 76 disposed along one longitudinal edge of the printhead IC. The bond pads 75 are connected via wire bonds (not shown) to provide power and logic signals to the CMOS drive circuitry in the printhead IC. Alignment origins 76 allow the printhead ICs that are in contact with each other to be aligned with one another while constructing the printhead using a suitable optical alignment tool (not shown).

The separate nozzle triangular portion 253 provides a sufficient solution to the problem of printing over the connection area, but nevertheless suffers from problems. First, the separate nozzle triangle portion 253 must be supplied with ink, and sharp twists in the longitudinally extending back ink supply passage can adversely affect ink supply to the nozzles in the triangle portion 253. Second, the separate nozzle triangular portion 253 increases the width of each printhead IC 251, thereby reducing wafer yield; Effectively, each printhead IC should be wide enough to accommodate r + 2 nozzle rows, but the printhead IC only has r nozzle rows.

The nozzle assemblies 200, 210, and 220 described herein are those having the ability to spray ink droplets to a plurality of predetermined different dot positions along the longitudinal axis, and thus to the problem of connecting printhead ICs. It provides a solution while maintaining a constant dot pitch across each connection area. Also, as shown in FIG. 28, printhead ICs 260 with nozzle rows that are seamless (i.e., no need for a separate nozzle triangle portion 253 shown in FIG. 7) can be glued together. This configuration of the printhead IC not only facilitates supply of ink along each nozzle row, but also increases wafer yield. In principle, there can be two methods that can be used to compensate for the 'lack' of nozzles across the connection area 257.

In the first method, the nozzles disposed toward both ends of the printhead IC 260 are configured to eject ink droplets in an inclined direction toward each end, as well as nozzles located toward the center of the printhead IC 260. They eject ink droplets in a direction perpendicular to the ink ejection surface. Referring to FIG. 29, there is shown a printhead IC 260 configured to eject ink droplets in a direction in which nozzles 264 disposed toward the right edge are inclined toward the right edge. Similarly, the nozzles 262 disposed toward the left edge are configured to eject ink droplets in a direction inclined toward the left edge. The nozzles 266 located toward the center of the printhead IC are configured to eject ink droplets in a direction perpendicular to the ink ejection surface. The nozzles 262, 264 and 266 have different ink droplet ejection characteristics, but they all have the unique ability to control the direction of the droplets and are called nozzles of the type shown in Figs. 18, 19 or 20. Of course, they are the same in each other.

The angle of inclination of the nozzle in the jet direction depends on the distance that the particular nozzle is from the center of the printhead IC 260. The nozzles located at the end of the printhead IC are configured to eject ink droplets in a more inclined direction than the nozzles located toward the center of the printhead IC. This gradual spreading outward from the center of the printhead IC 260 allows a constant dot pitch to be maintained over the entire length of the printhead IC.

Although the 'opening' phenomenon of droplet ejection is exaggerated in FIG. 29, it will be appreciated that as a result of such ejection, the average dot pitch of ejected ink droplets may be slightly larger than the nozzle pitch of the printhead IC 260. . However, because hundreds or thousands of nozzles are placed in each nozzle row, the final reduction in dot density relative to nozzle density is negligible. Typically, the average dot pitch will be less than 1% larger than the nozzle pitch of the printhead despite its spread droplet ejection.

By droplets being ejected in the oblique direction at the edges of the printhead IC 260, the actual printable area of a particular nozzle row is longer than the length of that nozzle row. The printable area may be 1 to 8 nozzles pitch longer than the nozzle row. This extended printable area allows the printhead IC to print within the connection area 257 between the printhead ICs 260 in contact with each other, thus requiring a separate nozzle triangle portion 253 as shown in FIG. There will be no.

Of course, it is equally possible to only allow nozzles located at one end of the printhead IC to eject ink droplets in an oblique direction. However, given the width of a typical connection area 257 (ie, the width between nozzles of a pair of abutting printhead ICs within the same nozzle row), the arrangement that caused the droplet injection shown in FIG. 29 is typical. Is preferred. This maximizes the range in which pairs of printhead ICs in contact with each other can compensate for nozzle 'lack' in the connection area 257.

The printhead IC 260 which causes the droplet ejection shown in Fig. 29 to open, each nozzle once in one line pass time in the event of lack of impossible nozzle compensation or when it is necessary to print at a higher dot density. While only spraying, the advantage is that the length of the printable area extends beyond the length of the corresponding nozzle row. In an alternative method, the printhead IC 270 may be configured such that the nozzles selected at the ends of each nozzle row spray more than once within one row pass time to compensate for the nozzle 'lack' of the connection area.

Referring to Fig. 30, a printhead IC 270 is shown in which most nozzles eject ink droplets in a direction perpendicular to the ink ejection surface of the printhead IC. However, at least one nozzle 272 at the end of the nozzle row ejects ink droplets toward the base dot position 274 (ie, at right angles to the ink ejection surface) and is directed toward each end of the printhead IC. It is configured to eject ink droplets toward the photographic second dot position 276. That is, the nozzles 272 are configured to eject two ink droplets within one heat pass time in a manner similar to the nozzles 231 in the high density printhead 230. However, the nozzles 272 maintain a constant dot pitch such that the nozzle pitch n is typically equal to the dot pitch d over the entire printable area of the printhead IC 270.

The printhead IC 270 has the advantage that there is no sacrifice of dot pitch relative to the nozzle pitch, but the nozzles 272 at the ends of each nozzle row are ink at twice the frequency of ejection of the other nozzles 271. The disadvantage is that you have to spray. As a result, since the nozzles 272 are more vulnerable to failure due to fatigue, the printhead IC 260 is generally more preferred for the solution of connecting the printhead ICs together.

improved MEMS Of CMOS  Integrated circuit

An important feature of the MEMS printhead design is the integration of MEMS actuators with the underlying CMOS driver circuit. In order to operate the nozzle, current must flow from the drive transistor in the CMOS drive circuit layer to the upper MEMS layer and back through the actuator back to the underlying CMOS drive circuit layer (e.g., to the ground plane in the CMOS layer). Given that thousands of actuators are installed in a single printhead IC, the efficiency of the current path must be maximized to minimize losses in terms of overall printhead efficiency.

So far, the applicant has described a nozzle assembly installed by extending a pair of linear pillars between a MEMS actuator (located in the nozzle chamber cover) and a lower CMOS driver circuit layer. Indeed, the fabrication of such parallel actuator pillars is shown and described here in FIGS. 5 and 6. The straight copper pillar leading to the MEMS layer has been found to improve the efficiency of the printhead compared to the highly meandering current path. Nevertheless, there is still room to improve the electrical efficiency of Applicants' MEMS printheads (as well as printhead ICs).

One problem associated with controlling thousands of operating states from common CMOS power and ground planes is known as 'ground bounce'. Ground recoil is a well known problem in integrated circuit designs, especially when the number of devices powered between the common power and ground planes is large. Ground recoil usually refers to an unwanted voltage drop across the power supply or ground plane and can be caused by many causes. Typical ground rebound causes include series resistance (“IR drop”), self-induction, and mutual induction between ground and power planes. Each of these phenomena can undesirably reduce the potential difference between the power supply and ground planes, causing ground recoil. This reduced potential difference inevitably leads to a reduction in the electrical efficiency of the integrated circuit, in particular here the printhead IC. It can be appreciated that the arrangement and configuration of the power and ground planes, as well as their connection, basically affects the ground recoil and the overall efficiency of the printhead.

Referring to FIG. 31, a portion of a printhead IC 300 with conductive tracks extending in parallel with the nozzle rows is shown in plan view. The uppermost polymer layer 19 is omitted in FIG. 31 for convenience of explanation.

The plurality of nozzles 210 (described in detail with respect to FIG. 18) are arranged in nozzle rows extending along the longitudinal axis of the printhead IC 300. Although FIG. 31 shows a pair of nozzle rows 302A and 302B, the printhead IC 300 may of course include more nozzle rows. The nozzle rows 302A and 302B are paired with each other such that one nozzle row 302A performs the printing task of 'even' dots and the other nozzle row 302B performs the printing task of 'odd' dots. It is arranged to be offset. The nozzle rows are typically paired in this way in the Applicant's printhead, for example, as can be clearly seen in FIG. 28.

First conductive track 303 is located between nozzle rows 302A and 302B. A first conductive track 303 is deposited over the nozzle plate 304 of the printhead IC 300, which defines the nozzle chamber cover 7 (see FIG. 10). Thus, the first conductive track 303 is generally coplanar with the thermoelastic beams 10 of the actuator 15, and together with the thermoelastic beam material (eg, vanadium-aluminum alloy) during MEMS fabrication. It can be formed by deposition at the same time. The conductivity of conductive track 303 may be further improved by depositing another conductive metal layer (eg, copper, titanium, aluminum, etc.) during MEMS fabrication. For example, it can be appreciated that a metal layer can be deposited prior to depositing a thermoelastic beam material (eg, co-deposition with the metal pads 9 shown in FIG. 8). Simply modifying the etch mask for the metal pads 9 can be used to define the conductive track 303. Thus, conductive track 303 may include a plurality of metal layers to optimize conductivity.

Each actuator 15 has a first terminal connected directly to the first conductive track 303 via a transverse connector 305. As can be seen in FIG. 31, each actuator in both nozzle rows 302A and 302B has a first terminal connected to the first conductive track 303. The first conductive track 303 is connected to the common reference plane of the underlying CMOS drive circuit layer through a plurality of conductive pillars 307, which are connected to the actuator pillars 8 described above with reference to FIG. 6. Made in a similar way. Thus, conductive track 303 may extend continuously along printhead IC 300 to provide a common reference plane for each actuator of a pair of nozzle rows. As discussed in more detail below, the common reference plane between nozzle columns 302A and 302B can be a power plane or ground plane depending on whether an nFET or pFET is employed in the CMOS driver circuit layer.

Alternatively, conductive track 303 may extend discontinuously along printhead IC 300 such that each portion of the conductive track provides one common reference plane for a group of actuators. Discontinuous conductive tracks 303 may be desirable when the separation of conductive tracks is difficult, but the conductive tracks still operate in the same manner as described above.

The second terminal of each actuator 15 is connected to the lower drive FET of the CMOS drive circuit layer through an actuator column 8 extending between the actuator and the CMOS drive circuit layer. Each actuator column 8 is entirely similar to the actuator column 8 shown in FIG. 6 and is formed in the same manner during MEMS fabrication. Thus, each actuator 15 is individually controlled by each drive FET.

In FIG. 31, the pair of second conductive tracks 310A and 310B also extend longitudinally along the printhead IC 300 to the side of the pair of nozzle rows 302A and 302B. The second conductive tracks 310A and 310B complement the first conductive track 303. That is, if the first conductive track 303 is a power plane, the second conductive tracks are all ground planes. Conversely, if the first conductive track 303 is a ground plane, the second conductive tracks are all power planes. The second conductive tracks 310A and 310B are not directly connected to the actuators 15, but are connected to the corresponding reference plane (power or ground) of the CMOS driver circuit layer by a plurality of conductive pillars 307.

It can be seen that the second conductive tracks 310 can be formed in a manner substantially similar to the first conductive track 303 during MEMS fabrication as described above. Thus, the second conductive tracks 310 are typically composed of a thermoelastic beam material and can be a plurality of layers so that the conductivity is increased.

The first and second conductive tracks 303 and 310 serve to essentially reduce the series resistance of the corresponding reference planes of the CMOS driver circuit layer. Thus, by providing the MEMS layer with conductive tracks electrically connected in parallel with the corresponding reference plane of the CMOS layer, the overall resistance of these reference planes is significantly reduced according to the simple Ohm's law. In general, conductive tracks are configured to minimize their resistance, for example by maximizing their width or depth as much as possible.

The series resistance of the ground plane or power plane can be reduced by at least 25%, at least 50%, at least 75% or at least 90% by conductive tracks in the MEMS layer. Likewise, the magnetic induction of the ground plane or the power plane can likewise be reduced. This significant reduction in series resistance and magnetic induction in both the ground plane and the power plane helps to minimize ground recoil in the printhead IC 300, thereby improving printhead efficiency. The inventors have found that the mutual induction between the power and ground planes is also reduced within the printhead IC 300 shown in FIG. 31, but the quantitative analysis of mutual induction requires complex simulation tests and thus the scope of the present invention. Is beyond.

32 and 33 schematically illustrate CMOS circuits for pFET and nFET drive transistors. The drive transistor (nFET or pFET) is directly connected to the second terminal of each actuator 15 through the actuator pillar 8 as shown in FIG.

In Fig. 32, the actuator 15 is connected between the drain of the pFET and the ground plane ("Vss"). The power plane ("Vpos") is connected to the source of the pFET while the gate receives a logic injection signal. When the pFET receives a low voltage through the gate (by the NAND gate), current flows through the pFET to actuate the actuator 15. In the pFET circuit, the first terminal of the actuator is connected to the ground plane provided by the first conductive track 303 while the second terminal of the actuator is connected to the pFET. Thus, the second conductive tracks provide power planes.

In FIG. 33, the actuator 15 is connected between the power plane (“Vpos”) and the source of the nFET. The ground plane ("Vss") is connected to the drain of the nFET while the gate receives a logic injection signal. When the nFET receives a high voltage at the gate (by the AND gate), current flows through the nFET to actuate the actuator 15. In this nFET circuit, the first terminal of the actuator is connected to the power plane provided by the first conductive track 303, while the second terminal of the actuator is connected to the nFET. Thus, the second conductive tracks provide ground planes.

33 and 33, it can be seen that the first conductive track 303 and the second conductive track 310 are compatible with pFETs or nFETs.

Of course, as described above, the advantage of using conductive tracks is by no means limited to the nozzles 210 shown in FIG. Any printhead IC with any type of actuator can in principle take advantage of the conductive tracks described above.

34 illustrates a printhead IC 400 including a plurality of nozzles 100 (of a type similar to those described with respect to FIG. 16) arranged in a pair of longitudinally extending nozzle rows 302A and 302B. Shows. The first conductive track 303 extends between the pair of nozzle rows 302A and 302B, and the second conductive tracks 310A and 310B are formed on the side of the pair of nozzle rows. Each actuator 15 of each nozzle 100 has a first terminal connected to the first conductive track 303 via a transverse connector 305, the second terminal being connected to the lower FET through the actuator column 8. Is connected to. Therefore, the printhead IC 400 operates similarly to the printhead IC 300 in that the conductive tracks 303 and 310 are connected to corresponding reference planes in the underlying CMOS drive circuit to provide common reference planes. I can understand that. In addition, the first conductive track 303 is directly connected to one terminal of each actuator to provide a common reference plane for each actuator in the two nozzle rows 302A and 302B.

Those skilled in the art will appreciate that many variations and / or modifications of the invention can be made without departing from the spirit and scope of the invention as broadly described, as shown in the specific embodiments. . Therefore, the embodiments of the present invention are for illustrative purposes in all respects and not for purposes of limitation.

Claims (20)

As an inkjet printhead,
A substrate comprising a drive circuit layer;
A nozzle chamber disposed on the top surface of the substrate and arranged in one or more nozzle rows extending longitudinally along the printhead, each having a bottom defined by the top surface, a lid spaced from the bottom, and A plurality of nozzle assemblies comprising an actuator for ejecting ink from a nozzle hole defined in the cover;
A nozzle plate extending across the printhead and at least partially defining the lids; And
At least one conductive track disposed on the nozzle plate and extending parallel to the nozzle rows in a longitudinal direction along the printhead;
And the conductive track is connected to a common reference plane of the drive circuit layer through a plurality of conductive pillars extending between the drive circuit layer and the conductive track. The method of claim 1,
And the common reference plane defines a ground plane or a power plane. The method of claim 1,
An inkjet printhead comprising at least one first conductive track, wherein the first conductive track is directly connected to a plurality of actuators in at least one nozzle row adjacent to the first conductive track. The method of claim 3,
An inkjet printhead further comprising at least one second conductive track, wherein the second conductive track is not directly connected to any actuators. The method of claim 3,
And the first conductive track extends continuously along the printhead to provide a common reference plane for each actuator in the nozzle row. The method of claim 3,
And the first conductive track extends discontinuously along the printhead to provide a common reference plane for the group of actuators in the nozzle row. The method of claim 3,
Wherein the first conductive track is located between each pair of nozzle rows and provides a common reference plane for a plurality of actuators of two nozzle rows of each pair. The method of claim 3,
Wherein each actuator has a first terminal connected directly to the first conductive track and a second terminal connected to a drive transistor of the drive circuit layer. 9. The method of claim 8,
Each cover includes at least one actuator, the first terminal of each actuator being connected to the first conductive track via a transverse connector extending transversely across the nozzle plate relative to the first conductive track. Inkjet printhead connected. 10. The method of claim 9,
And the second terminal is connected to the drive transistor through an actuator column extending between the drive circuit layer and the second terminal. The method of claim 10,
And the actuator pillars are perpendicular to the plane of the first conductive track. 10. The method of claim 9,
Each cover includes at least one movable paddle comprising a respective thermal bend actuator, the paddle being movable towards the bottom of each nozzle chamber to inject ink from the nozzle aperture, the thermal bend actuator being:
An upper thermoelastic beam having the first and second terminals; And
An inkjet printhead comprising a lower passive beam deposited on the thermoelastic beam such that when the current flows through the thermoelastic beam, the thermoelastic beam expands relative to the passive beam such that each paddle bends toward the bottom of the nozzle chamber. The method of claim 12,
And the thermoelastic beam is coplanar with the conductive track. The method of claim 12,
And the thermoelastic beam and the conductive track are made of the same material. The method of claim 1,
And the nozzle plate is made of a ceramic material. 5. The method of claim 4,
The drive circuit layer includes a drive field effect transistor (FET) for each actuator, each drive FET having a gate for receiving a logic injection signal, a source electrically connected to the power plane, and a drain electrically connected to the ground plane. The drive FET includes:
A pFET coupled with the actuator between the drain and the ground plane; or
An inkjet printhead that is one of an nFET to which the actuator is coupled between the power plane and the source. 17. The method of claim 16,
The drive FET is a pFET, the first conductive track provides a ground plane, the first terminal of the actuator is connected to the first conductive track, and the second terminal of the actuator is connected to the drain of the pFET. Inkjet printheads. 18. The method of claim 17,
And the second conductive track provides a power plane and is connected to a source of the pFET. 17. The method of claim 16,
The drive FET is an nFET, the first conductive track provides a power plane, and the first terminal of the actuator is connected to the first conductive track, and the second terminal of the actuator is connected to the source of the nFET. Inkjet printheads. 20. The method of claim 19,
And the second conductive track provides a ground plane and is connected to the drain of the nFET.

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