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WO2013016003A1 - Tête d'impression à jet d'encre comportant des résistances de test - Google Patents

Tête d'impression à jet d'encre comportant des résistances de test Download PDF

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Publication number
WO2013016003A1
WO2013016003A1 PCT/US2012/046403 US2012046403W WO2013016003A1 WO 2013016003 A1 WO2013016003 A1 WO 2013016003A1 US 2012046403 W US2012046403 W US 2012046403W WO 2013016003 A1 WO2013016003 A1 WO 2013016003A1
Authority
WO
WIPO (PCT)
Prior art keywords
nominal
length
resistive heater
width
array
Prior art date
Application number
PCT/US2012/046403
Other languages
English (en)
Inventor
Roger G. MARKHAM
David Paul Trauernicht
John Andrew Lebens
Christopher R. Morton
Original Assignee
Eastman Kodak Company
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US13/190,505 external-priority patent/US8439477B2/en
Priority claimed from US13/190,504 external-priority patent/US20130027449A1/en
Application filed by Eastman Kodak Company filed Critical Eastman Kodak Company
Publication of WO2013016003A1 publication Critical patent/WO2013016003A1/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
    • B41J2/01—Ink jet
    • B41J2/015—Ink jet characterised by the jet generation process
    • B41J2/04—Ink jet characterised by the jet generation process generating single droplets or particles on demand
    • B41J2/045—Ink jet characterised by the jet generation process generating single droplets or particles on demand by pressure, e.g. electromechanical transducers
    • B41J2/04501—Control methods or devices therefor, e.g. driver circuits, control circuits
    • B41J2/0458—Control methods or devices therefor, e.g. driver circuits, control circuits controlling heads based on heating elements forming bubbles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
    • B41J2/01—Ink jet
    • B41J2/015—Ink jet characterised by the jet generation process
    • B41J2/04—Ink jet characterised by the jet generation process generating single droplets or particles on demand
    • B41J2/045—Ink jet characterised by the jet generation process generating single droplets or particles on demand by pressure, e.g. electromechanical transducers
    • B41J2/04501—Control methods or devices therefor, e.g. driver circuits, control circuits
    • B41J2/04506—Control methods or devices therefor, e.g. driver circuits, control circuits aiming at correcting manufacturing tolerances
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
    • B41J2/01—Ink jet
    • B41J2/015—Ink jet characterised by the jet generation process
    • B41J2/04—Ink jet characterised by the jet generation process generating single droplets or particles on demand
    • B41J2/045—Ink jet characterised by the jet generation process generating single droplets or particles on demand by pressure, e.g. electromechanical transducers
    • B41J2/04501—Control methods or devices therefor, e.g. driver circuits, control circuits
    • B41J2/04538—Control methods or devices therefor, e.g. driver circuits, control circuits involving calculation of heater resistance
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
    • B41J2/01—Ink jet
    • B41J2/015—Ink jet characterised by the jet generation process
    • B41J2/04—Ink jet characterised by the jet generation process generating single droplets or particles on demand
    • B41J2/045—Ink jet characterised by the jet generation process generating single droplets or particles on demand by pressure, e.g. electromechanical transducers
    • B41J2/04501—Control methods or devices therefor, e.g. driver circuits, control circuits
    • B41J2/04565—Control methods or devices therefor, e.g. driver circuits, control circuits detecting heater resistance
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
    • B41J2/01—Ink jet
    • B41J2/015—Ink jet characterised by the jet generation process
    • B41J2/04—Ink jet characterised by the jet generation process generating single droplets or particles on demand
    • B41J2/045—Ink jet characterised by the jet generation process generating single droplets or particles on demand by pressure, e.g. electromechanical transducers
    • B41J2/04501—Control methods or devices therefor, e.g. driver circuits, control circuits
    • B41J2/0459—Height of the driving signal being adjusted
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
    • B41J2/01—Ink jet
    • B41J2/015—Ink jet characterised by the jet generation process
    • B41J2/04—Ink jet characterised by the jet generation process generating single droplets or particles on demand
    • B41J2/045—Ink jet characterised by the jet generation process generating single droplets or particles on demand by pressure, e.g. electromechanical transducers
    • B41J2/04501—Control methods or devices therefor, e.g. driver circuits, control circuits
    • B41J2/04591—Width of the driving signal being adjusted
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2202/00—Embodiments of or processes related to ink-jet or thermal heads
    • B41J2202/01—Embodiments of or processes related to ink-jet heads
    • B41J2202/11—Embodiments of or processes related to ink-jet heads characterised by specific geometrical characteristics
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2202/00—Embodiments of or processes related to ink-jet or thermal heads
    • B41J2202/01—Embodiments of or processes related to ink-jet heads
    • B41J2202/17—Readable information on the head

Definitions

  • the present invention relates generally to an inkjet printhead including an array of resistive heaters, and more particularly to test resistors for characterizing the manufacturing variability of the resistive heaters.
  • Inkjet printing has become a pervasive printing technology.
  • Inkjet printing systems include one or more arrays of drop ejectors provided on an inkjet printing device, in which each drop ejector is actuated at times and locations where it is required to deposit a dot of ink on the recording medium to print the image.
  • a drop ejector includes a pressurization chamber, a drop forming mechanism (such as a resistive heater) and a nozzle.
  • a thermal inkjet drop ejector ink is supplied to the pressurization chamber.
  • a resistive heater formed for example as a patterned thin film, is at least partially enclosed within the pressurization chamber.
  • ink in contact with the resistive heater is vaporized to form a bubble.
  • the bubble grows and causes a drop of ink to be ejected through a nozzle associated with the pressurization chamber.
  • the ink vapor bubble either is vented through the nozzle or condenses within the pressurization chamber, depending upon the design of the drop ejector. Subsequently, additional ink fills the pressurization chamber and the drop ejector is ready to eject another drop of ink.
  • Thermal inkjet printing devices having several hundred or more drop ejectors per printing device, also typically include driver and logic electronics to facilitate electrical interconnection to the resistive heaters.
  • Thermal inkjet printing devices are typically fabricated as a plurality of die on a wafer.
  • One or more die are packaged into an inkjet printhead, and the printhead is installed in an inkjet printer that includes one or more ink supplies, a pulse source, a controller, and an advance system for advancing recording medium relative to the inkjet printhead.
  • the reliability, energy efficiency and drop volume uniformity associated with the inkjet printhead can depend upon the manufacturing variability of the resistive heaters from die to die and from wafer to wafer.
  • the voltage and/or pulse duration applied to the resistive heaters is somewhat larger than the "threshold" pulse conditions that are known to begin to eject drops of ink.
  • a pulse voltage can be set to be 10% higher than the threshold voltage. This higher voltage assures that drops are ejected even if resistances vary within the die, or if firing conditions vary (such as due to different amounts of voltage sag associated with parasitic resistances associated with firing more than one heater at a time, or firing heaters toward the center of the die as opposed to heaters nearer to the edge of the die).
  • test structures that are capable of determining the actual sheet resistivity p s , the actual length L, and optionally the actual width W of the resistive heaters on a printhead die.
  • An inkjet printhead comprising an array of drop ejectors, a first drop ejector of the array including a first resistive heater having a first nominal length and a first nominal width; and a first configuration test resistor disposed proximate the first resistive heater, the first configuration test resistor including a second nominal length and a second nominal width, wherein the second nominal length is different from the first nominal length.
  • FIG. 1 is a schematic representation of an inkjet printer system
  • FIG. 2 is a perspective view of a portion of a printhead chassis
  • FIG. 3 is a perspective view of a portion of a carriage printer
  • FIG. 4 is a schematic side view of an exemplary paper path in a carriage printer
  • FIG. 5 is a schematic representation of the electrical features on a prior art thermal inkjet printhead die
  • FIG. 6 is a schematic representation of the electrical features including test resistors on a thermal inkjet printhead die according to an embodiment of the invention
  • FIGS. 7A and 7B show different configurations of resistive heaters and corresponding test resistors.
  • FIG. 8 shows a wafer including a plurality of printhead die.
  • test resistor is a resistor used primarily or solely for testing purposes, such as gathering data that is relevant to geometrical characteristics or electrical resistance characteristics of resistive heaters that are associated with drop ejectors.
  • Inkjet printer system 10 includes an image data source 12, which provides data signals that are interpreted by a controller 14 as being commands to eject drops.
  • Controller 14 includes an image processing unit 15 for rendering images for printing, and outputs signals to an electrical pulse source 16 of electrical energy pulses that are inputted to an inkjet printhead 100, which includes at least one inkjet printhead die 110.
  • FIG. 1 there are two nozzle arrays.
  • Nozzles 121 in the first nozzle array 120 have a larger opening area than nozzles 131 in the second nozzle array 130.
  • each of the two nozzle arrays has two staggered rows of nozzles, each row having a nozzle density of 600 per inch.
  • ink delivery pathway 122 is in fluid communication with the first nozzle array 120
  • ink delivery pathway 132 is in fluid communication with the second nozzle array 130. Portions of ink delivery pathways 122 and 132 are shown in FIG. 1 as openings through printhead die substrate 111.
  • One or more inkjet printhead die 110 will be included in inkjet printhead 100, but for greater clarity only one inkjet printhead die 110 is shown in FIG. 1.
  • the printhead die are arranged on a support member as discussed below relative to FIG. 2.
  • first fluid source 18 supplies ink to first nozzle array 120 via ink delivery pathway 122
  • second fluid source 19 supplies ink to second nozzle array 130 via ink delivery pathway 132.
  • distinct fluid sources 18 and 19 are shown, in some applications it may be beneficial to have a single fluid source supplying ink to both the first nozzle array 120 and the second nozzle array 130 via ink delivery pathways 122 and 132 respectively. Also, in some embodiments, fewer than two or more than two nozzle arrays can be included on printhead die 110. In some embodiments, all nozzles on inkjet printhead die 110 can be the same size, rather than having multiple sized nozzles on inkjet printhead die 110. Not shown in FIG. 1, are the drop forming mechanisms and pressurization chambers associated with the nozzles to form an array of drop ejectors corresponding to the nozzle array.
  • Drop forming mechanisms can be of a variety of types, some of which include a resistive heater to vaporize a portion of ink and thereby cause ejection of a droplet, or an actuator which is made to move (for example, by resistively heating a bi-layer element) and thereby cause ejection.
  • electrical pulses from electrical pulse source 16 are sent to the various drop ejectors according to the desired deposition pattern.
  • droplets 181 ejected from the first nozzle array 120 are larger than droplets 182 ejected from the second nozzle array 130, due to the larger nozzle opening area.
  • drop forming mechanisms (not shown) associated respectively with nozzle arrays 120 and 130 are also sized differently in order to optimize the drop ejection process for the different sized drops.
  • droplets of ink are deposited on a recording medium 20.
  • FIG. 2 shows a perspective view of a portion of a printhead chassis
  • Printhead chassis 250 which is an example of an inkjet printhead 100 suitable for use in a carriage printer.
  • Printhead chassis 250 includes three printhead die 251 (similar to printhead die 110 in FIG. 1), each printhead die 251 containing two nozzle arrays 253, so that printhead chassis 250 contains six nozzle arrays 253 altogether.
  • the three printhead die 251 are affixed to a mounting substrate 255 for support and for fluidic connection to ink supplies.
  • the six nozzle arrays 253 in this example can each be connected to separate ink sources (not shown in FIG. 2); such as cyan, magenta, yellow, text black, photo black, and a colorless protective printing fluid.
  • Each of the six nozzle arrays 253 is disposed along nozzle array direction 254, and the length of each nozzle array along the nozzle array direction 254 is typically on the order of 1 inch or less. Typical lengths of recording media are 6 inches for photographic prints (4 inches by 6 inches) or 11 inches for paper (8.5 by 11 inches). Thus, in order to print a full image, a number of swaths are successively printed while moving printhead chassis 250 across the recording medium 20. Following the printing of a swath, the recording medium 20 is advanced along a media advance direction that is substantially parallel to nozzle array direction 254.
  • a flex circuit 257 to which the printhead die 251 are electrically interconnected, for example, by wire bonding or TAB bonding. The interconnections are covered by an encapsulant 256 to protect them. Flex circuit 257 bends around the side of printhead chassis 250 and connects to connector board 258. When printhead chassis 250 is mounted into the carriage 200 (see FIG. 3), connector board 258 is electrically connected to a connector (not shown) on the carriage 200, so that electrical signals can be transmitted to the printhead die 251.
  • FIG. 3 shows a portion of a desktop carriage printer. Some of the parts of the printer have been hidden in the view shown in FIG. 3 so that other parts can be more clearly seen.
  • Printer chassis 300 has a print region 303 across which carriage 200 is moved back and forth in carriage scan direction 305 along the X axis, between the right side 306 and the left side 307 of printer chassis 300, while drops are ejected from printhead die 251 (not shown in FIG. 3) on printhead chassis 250 that is mounted on carriage 200.
  • Carriage motor 380 moves belt 384 to move carriage 200 along carriage guide rail 382.
  • An encoder sensor (not shown) is mounted on carriage 200 and indicates carriage location relative to an encoder fence 383.
  • Printhead chassis 250 is mounted in carriage 200, and multi- chamber ink supply 262 and single-chamber ink supply 264 are mounted in the printhead chassis 250.
  • the mounting orientation of printhead chassis 250 is rotated relative to the view in FIG. 2, so that the printhead die 251 are located at the bottom side of printhead chassis 250, the droplets of ink being ejected downward onto the recording medium in print region 303 in the view of FIG. 3.
  • Multi-chamber ink supply 262 in this example, contains five ink sources: cyan, magenta, yellow, photo black, and colorless protective fluid; while single-chamber ink supply 264 contains the ink source for text black.
  • Paper or other recording medium (sometimes generically referred to as paper or media herein) is loaded along paper load entry direction 302 toward the front of printer chassis 308.
  • a variety of rollers are used to advance the medium through the printer as shown schematically in the side view of FIG. 4.
  • a pickup roller 320 moves the top piece or sheet 371 of a stack 370 of paper or other recording medium in the direction of arrow, paper load entry direction 302.
  • a turn roller 322 acts to move the paper around a C-shaped path (in cooperation with a curved rear wall surface) so that the paper continues to advance along media advance direction 304 from the rear 309 of the printer chassis (with reference also to FIG. 3).
  • Feed roller 312 includes a feed roller shaft along its axis, and feed roller gear 311 is mounted on the feed roller shaft.
  • Feed roller 312 can include a separate roller mounted on the feed roller shaft, or can include a thin high friction coating on the feed roller shaft.
  • a rotary encoder (not shown) can be coaxially mounted on the feed roller shaft in order to monitor the angular rotation of the feed roller.
  • the motor that powers the paper advance rollers is not shown in
  • the hole 310 at the right side of the printer chassis 306 is where the motor gear (not shown) protrudes through in order to engage feed roller gear 311, as well as the gear for the discharge roller (not shown).
  • the motor gear for normal paper pick-up and feeding, it is desired that all rollers rotate in forward rotation direction 313.
  • the maintenance station 330 Toward the left side of the printer chassis 307, in the example of FIG. 3, is the maintenance station 330.
  • the electronics board 390 which includes cable connectors 392 for communicating via cables (not shown) to the printhead carriage 200 and from there to the printhead chassis 250. Also on the electronics board are typically mounted motor controllers for the carriage motor 380 and for the paper advance motor, a processor and/or other control electronics (shown schematically as controller 14 and image processing unit 15 in FIG. 1) for controlling the printing process, and an optional connector for a cable to a host computer.
  • FIG. 5 shows a schematic representation of a thermal inkjet printhead die 251 according to the prior art, showing resistive heater array 410, a corresponding transistor array 420, a logic section 430, and other electrical features, but not showing the fluidic features such as the corresponding nozzle array, the pressurization chambers, the ink inlet or other ink passageways.
  • Resistive heater array 410 includes a total of N resistive heaters (R ⁇ to RN), but only four at each end of the array are shown for simplicity.
  • Transistor array 420 includes a driver transistor for each resistive heater for providing electrical pulses to the resistive heaters for vaporizing ink to eject drops of ink.
  • a high voltage (typically on the order of 25 volts to 40 volts) is applied to common 440 at pads 456 and the transistors in transistor array 420 are controllably turned on or off to pulse the resistive heaters as needed to eject drops in the proper locations to form an image.
  • Logic section 430 includes shift registers and other circuitry to control transistor array according to signals provided by controller 14 and electrical pulse source 16 (FIG. 1).
  • Bond pads 450 and 456 are electrically connected to flex circuit 257 in printhead 250 as described above relative to FIG. 2 in order to provide high voltage to the common 440, as well as ground, logic power, data, clock and other electrical signals as needed to operate the printhead die 251.
  • Pads 455 are test pads connected to end resistive heaters Rj and RN in order to measure their resistance, as might be done according to methods described in US. Patent No. 5,504,507 referred to in the background.
  • test pads 455 be connected to the end resistive heaters Ri and RN, but it is typically preferred to test the end resistive heaters because it is easier to provide test leads 454 to the end resistive heaters without requiring crossovers, and the leads 454 can be very short so that they have low resistance.
  • Leads 454 and pads 450, 455 and 456 are made of a thin metal film such as aluminum and have much lower resistance than the resistive heaters, which are made of a resistive material such as tantalum silicon nitride. By having low resistance leads 454 and pads 455 and 456, a nominal resistance can be assumed for the leads and pads.
  • resistive heaters Ri and RN can be characterized for each printhead die, in order to provide a correction for pulsing conditions as disclosed in US Patent 5,504,507.
  • Embodiments of the present invention provide improved test resistors that enable determination of the sheet resistance of the resistive heaters, as well as resistive heater length and optionally the resistive heater width for each printhead die. Such measurements provide improved accuracy in the correction relative to US Patent 5,504,507 because they allow correction for power density and energy density dissipated in the resistive heaters, rather than merely for power and energy.
  • FIG. 6 shows an embodiment in a thermal inkjet printhead die 251 that is similar to the prior art printhead die shown in FIG. 5, but with additional test resistors RL and Rw-
  • FIG. 6 shows a schematic representation of a thermal inkjet printhead die 251 having a resistive heater array 410 that corresponds to a drop ejector array, a corresponding transistor array 420, a logic section 430, and other electrical features, but not showing the fluidic features such as the corresponding nozzle array, the pressurization chambers, the ink inlet or other ink passageways.
  • a single straight line array 410 is shown in the example of FIG. 6, but there can be multiple resistive heater arrays and/or staggered arrays as disclosed above relative to FIGS.
  • FIG. 7 A shows a close-up view of resistive heaters Rj to R4 as well as length test resistor RL and width test resistor Rw- All of the resistive heaters (including up through RN) have a nominal length L and a nominal width W.
  • Length test resistor L has a nominal length equal to aL and a nominal width equal to cW.
  • Width test resistor Rw has a nominal width equal to bW and a nominal length equal to dL.
  • the sheet resistance p s of the resistor material can vary significantly across a wafer or especially from wafer to wafer or batch to batch due to changes in thickness or chemical composition, such manufacturing variability is very small for resistors that are very close to each other.
  • the resistive heater spacing in a resistive heater array 410 can be on the order of 1 /600 th of an inch (about 42 microns) the distance from Rj to RL and R is typically less than about 100 microns, and similarly for RN, RL and Rw at the other end of the array.
  • mask exposure, development, and etching conditions are sufficiently similar on such a localized scale that any differences from nominal widths or lengths between Rj and its neighboring test resistors RL and Rw can be assumed to be essentially identical.
  • a test pad 457 is connected to length test resistor RL, and a test pad 458 is connected to width test resistor Rw- Leads connecting test pad 457 to length test resistor RL and connecting test pad 458 to width test resistor Rw are shown but not labeled in FIG. 6.
  • these leads like lead 454 have a nominal resistance that is on the order of an ohm, so that any variations in lead resistance are small compared to the resistance of the resistive heater which is typically several hundred ohms. Resistance of the respective test resistors can be measured by probes contacting test pads 457, 458 and pad 456 that is connected to the common. Similarly, the resistance of Ri can be measured by probes contacting test pad 455 (connected to Ri) and pad 456.
  • an additional test resistor is provided with nominal length and nominal width equal to those of Ri, so that it is not Ri and R themselves (the resistive heaters
  • a target sheet resistance is aimed at, such that all of the resistive heaters R
  • Equations (2) and (3) can be solved for 6 L as shown in equation (4) below:
  • 6 L L(R L - aR / (Ri - R L ) (4).
  • the actual length of resistive heater Ri is L + 6L, where 5L is determined by parameters that are either measured (RL and Rj) or given as nominal (a and L).
  • resistive heater Ri is W + 5w, where 6w is determined by parameters that are either measured (RL and Rj) or given as nominal (b and W).
  • the actual power density V 2 /p s L 2 (see equation 1) in the vicinity of Rj and RN for each printhead can be determined.
  • the energy density due to a pulse width ⁇ is the power density times ⁇ , so that the energy density is ⁇ V 2 /p s L 2 .
  • Deviations from the nominal sheet resistance or the nominal length of the resistive heater can thus be corrected for by modifying the amplitude V or the pulsewidth ⁇ .
  • the actual sheet resistance and the actual length of Ri or R or an average of the actual sheet resistances and actual lengths for each resistive heater array can be stored on the inkjet printhead (for example on printhead die 251) as an electronically readable code, and then read by the printer when the printhead is installed, so that controller 14 (FIG. 1) can adjust pulse amplitude (i.e. the voltage) or pulse width (i.e. the pulse duration) accordingly for the resistive heater array(s) in that particular printhead. For example, if the actual sheet resistance is determined to be less than the nominal sheet resistance then the pulse duration and/or the voltage would be decreased relative to a nominal pulse duration or voltage. Similarly, if the actual length of the resistive heater is determined to be less than the nominal length then the pulse duration and/or the voltage would be decreased relative to a nominal pulse duration or voltage.
  • One can substitute the expression for ⁇ ⁇ ⁇ into the expression for 5 L and then reduce the resulting expression algebraically to an expression for 6 L in terms of known parameters. Similarly one can solve 6w in terms of known parameters.
  • width test resistor As described above so that the actual sheet resistance can be calculated.
  • the width of the resistive heaters does not vary much across the wafer.
  • a width test resistor is not required on each printhead die. Rather, one or more width test resistors can be included on the wafer from which the die are later cut. Such an approach can allow the printhead die to be slightly shorter due to fewer test resistors, which can result in the printhead die being slightly less costly.
  • FIG. 7B shows resistive heaters Ri to R4 and associated test resistors RL and Rw that are configured as a first resistor leg 411 , a second resistor leg 412 next to the first resistor leg 411 , and a shorting bar 413 that joins two adjacent ends of the first resistor leg 411 and the second resistor leg 412.
  • Shorting bar 413 is made of metal such as aluminum, while resistor legs 411 and 412 are made of a much more highly resistive material.
  • a common for high voltage (similar to common 440 in FIG.
  • the nominal length associated with the resistive heater Ri or the test resistors RL and Rw is the sum of the nominal lengths of first resistor leg 411 and second resistor leg 412.
  • the nominal width associated with the resistive heater Ri or the test resistors RL and R is equal to the nominal width of one of the resistor legs 411 and 412, which are assumed to have the same nominal width as each other.
  • the determination of actual length, actual width and actual sheet resistance for the configuration shown in FIG. 7B is done in a similar manner as described above for the configuration of FIG. 7 A.
  • FIG. 8 shows an example of a wafer 460 including a plurality of printhead die 251 arranged in a plurality of rows and columns including 3 central columns of 28 die each, plus 2 columns of 26 die each and 2 columns of 18 die each for a total of 172 die.
  • the actual number of printhead die on a wafer depends upon the size of the die, the aspect ratio of the die and the size of a wafer. A typical wafer size is 8 inches in diameter.
  • the test resistor(s) on each printhead die 251 would be measured during electrical wafer probing which is done in order to identify defective die, as well as to characterize the die.
  • a method of characterizing an array of resistive heaters having a first resistive heater (e.g. Ri) with a nominal sheet resistance, a first nominal length and a first nominal width includes a) providing a first configuration test resistor nearby the first resistive heater, the first
  • configuration test resistor including a width that is equal to the first nominal width and a second nominal length that is different from the first nominal length; b) measuring a resistance of the first resistive heater; c) measuring a resistance of the first configuration test resistor; and d) determining the actual sheet resistance and the actual length of the first resistive heater based on the measured resistance of the first resistive heater and the first configuration test resistor.
  • the method also includes e) providing a second configuration test resistor nearby the first resistive heater, the second configuration test resistor including a length that is equal to the first nominal length, and a third nominal width that is different from the first nominal width; f) measuring a resistance of the second configuration test resistor; and g) determining the actual width of the first resistive heater based on the measured resistances of the first resistive heater and the second configuration test resistor.
  • the determined actual sheet resistance is also based on the measured resistance of the second configuration test resistor.
  • the method described above is performed for each of the plurality of die on a wafer in order to provide the actual sheet resistance, the actual length and optionally the actual width of the first resistive heater for each of the plurality of die.
  • is located on the left side and RN is located on the right side of the printhead die 251 in wafer 460 of FIG. 8, then RN for a first die in a first column is typically located closer to Ri of a second die located in the same row but one column to the right.
  • RN for a first die in a first column is typically located closer to Ri of a second die located in the same row but one column to the right.
  • Manufacturing of the electrical features can be done using standard wafer fabrication processes that are well known in the art. Such fabrication processes can include thin film deposition of resistive materials or metals by sputtering (nonreactive or reactive), and patterning of the thin films by patterning a photoresist by exposure through a mask and subsequent removal of thin film material by plasma etching or wet chemical etching.
  • the actual sheet resistances, actual lengths, and optionally the actual widths of the resistive heaters can be provided to the wafer manufacturer on a die by die location basis for each wafer. This data can be used to modify fabrication processes as needed. For example, if it is found that the actual widths are always too small, the resistor mask could be biased to increase the width. If the actual lengths are always too small, the aluminum etching process or the metal mask can be adjusted. If the actual sheet resistance is off target, the reactive sputtering process or its duration can be modified. If there is systematic variation by printhead die location across all wafers, the processes can be modified to make the variation smaller. In any case, providing the data to the wafer manufacturer can result in improved uniformity of actual lengths, actual widths and actual sheet resistances.
  • test resistors and method of characterizing resistor arrays can also be advantageously used for the multiple printhead die in a pagewidth printhead.
  • Ink delivery pathway (for first nozzle array)
  • Ink delivery pathway (for second nozzle array)
  • Droplet(s) (ejected from first nozzle array)
  • Test pads (for length test resistors)
  • Test pads (for width test resistors)

Landscapes

  • Particle Formation And Scattering Control In Inkjet Printers (AREA)

Abstract

L'invention porte sur une tête d'impression à jet d'encre, laquelle tête comprend un groupement d'éjecteurs de gouttes, un premier injecteur de gouttes du groupement comprenant un premier élément chauffant résistif (R1) ayant une première longueur nominale et une première largeur nominale ; et une première résistance de test de configuration (Rl) disposée à proximité du premier élément chauffant résistif (Rl), la première résistance de tête de configuration (RL) comprenant une seconde longueur nominale et une seconde largeur nominale, la seconde longueur nominale étant différente de la première longueur nominale.
PCT/US2012/046403 2011-07-26 2012-07-12 Tête d'impression à jet d'encre comportant des résistances de test WO2013016003A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US13/190,505 US8439477B2 (en) 2011-07-26 2011-07-26 Method of characterizing array of resistive heaters
US13/190,504 US20130027449A1 (en) 2011-07-26 2011-07-26 Inkjet printhead with test resistors
US13/190,504 2011-07-26
US13/190,505 2011-07-26

Publications (1)

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WO2013016003A1 true WO2013016003A1 (fr) 2013-01-31

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4560583A (en) * 1984-06-29 1985-12-24 International Business Machines Corporation Resistor design system
EP0626266A2 (fr) * 1993-05-27 1994-11-30 Canon Kabushiki Kaisha Appareil d'enregistrement commandé par les caractéristiques de la tête et méthode d'enregistrement
EP0641656A2 (fr) * 1993-09-08 1995-03-08 Canon Kabushiki Kaisha Imprimante par jet d'encre
US5504507A (en) 1992-10-08 1996-04-02 Xerox Corporation Electronically readable performance data on a thermal ink jet printhead chip
US7350902B2 (en) 2004-11-18 2008-04-01 Eastman Kodak Company Fluid ejection device nozzle array configuration

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4560583A (en) * 1984-06-29 1985-12-24 International Business Machines Corporation Resistor design system
US5504507A (en) 1992-10-08 1996-04-02 Xerox Corporation Electronically readable performance data on a thermal ink jet printhead chip
EP0626266A2 (fr) * 1993-05-27 1994-11-30 Canon Kabushiki Kaisha Appareil d'enregistrement commandé par les caractéristiques de la tête et méthode d'enregistrement
EP0641656A2 (fr) * 1993-09-08 1995-03-08 Canon Kabushiki Kaisha Imprimante par jet d'encre
US7350902B2 (en) 2004-11-18 2008-04-01 Eastman Kodak Company Fluid ejection device nozzle array configuration

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