EP0437062A2 - Verfahren und Vorrichtung zum Drucken mit einem auf Abruf arbeitenden Tintenstrahldruckkopf mittels eines elektrischen Feldes - Google Patents

Verfahren und Vorrichtung zum Drucken mit einem auf Abruf arbeitenden Tintenstrahldruckkopf mittels eines elektrischen Feldes Download PDF

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Publication number
EP0437062A2
EP0437062A2 EP90313723A EP90313723A EP0437062A2 EP 0437062 A2 EP0437062 A2 EP 0437062A2 EP 90313723 A EP90313723 A EP 90313723A EP 90313723 A EP90313723 A EP 90313723A EP 0437062 A2 EP0437062 A2 EP 0437062A2
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EP
European Patent Office
Prior art keywords
ink
electric field
drop
drops
outlet
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Ceased
Application number
EP90313723A
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English (en)
French (fr)
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EP0437062A3 (en
Inventor
Joy Roy
Susan C. Schoening
Hue P. Le
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Tektronix Inc
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Tektronix Inc
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Publication of EP0437062A2 publication Critical patent/EP0437062A2/de
Publication of EP0437062A3 publication Critical patent/EP0437062A3/en
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    • 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
    • B41J2/21—Ink jet for multi-colour printing
    • B41J2/2121—Ink jet for multi-colour printing characterised by dot size, e.g. combinations of printed dots of different diameter
    • B41J2/2128—Ink jet for multi-colour printing characterised by dot size, e.g. combinations of printed dots of different diameter by means of energy modulation

Definitions

  • the present invention relates to printing with a drop-on-demand ink jet print head using an electric field which remains time invariant during ink drop ejection and travel of the drops toward print medium.
  • the present invention is particularly useful in grey scale or half-tone printing in which ink drop size is selectively varied during printing.
  • Ink jet printers and in particular drop-on-demand ink jet printers having print heads with acoustic drivers for ink drop formation are well known in the art.
  • the principle behind an impulse ink jet of this type is the generation of a pressure wave in an ink chamber and subsequent emission of ink droplets from the ink chamber through a nozzle orifice as a result of the pressure wave.
  • a wide variety of acoustic drivers are employed in ink jet print heads of this type.
  • the drivers may consist of a transducer formed by a piezoceramic material bonded to a thin diaphragm.
  • Piezoelectric drivers may be of any suitable shape such as circular, polygonal, cylindrical, annular-cylindrical, etc. In addition, piezoelectric drivers may be operated in various modes of deflection, such as in the bending mode, shear mode, and longitudinal mode. Other types of acoustic drivers for generating pressure waves in ink include heater-bubble source drivers (so called bubble or thermal ink jets) and electromagnet-solenoid drivers. In general, it is desirable in an ink jet print head to employ a geometry that permits multiple nozzles to be positioned in a densely packed array with each nozzle being driven by an associated acoustic driver.
  • drop volume can be selected to provide optimum spot optical density to effectively produce high resolution printing.
  • a draft-mode print quality can be chosen.
  • printers are also useful in applications requiring half-tone images, such as involving the control of color saturation, hue and lightness.
  • U.S. Patent No. 4,513,299 of Lee, et al. describes one approach for achieving variations in ink drop size.
  • an electromechanical transducer is coupled to an ink chamber and is driven by one or more electrical drive signals of the same polarity which are each separated by a fixed time delay. This time delay is short with respect to the drop-on-demand drop production rate.
  • Each electrical drive signal ejects a predetermined volume of ink with the ejected volumes of ink merging to form a single drop.
  • An increase in the number of electrical drive signals between the formation and ejection of a drop causes an increase in the drop volume.
  • This patent mentions that the various sized drops travel at a constant velocity to the print medium.
  • U.S. Patent No. 4,561,025 of Tsuzuki describes another printer for printing half-tone images with ink drops or dots of varying sizes.
  • the diameter of each dot is controlled by controlling the energy content of the driving pulse which causes the dot, for example, by varying the amplitude or pulse width of the driving pulse.
  • U.S. Patent No. 4,563,689 of Murakimi, et al. discloses still another approach for achieving half-tone printing.
  • a preceding pulse is applied to an electromechanical transducer prior to a main pulse.
  • the preceding pulse is described as a voltage pulse that is applied to a piezoelectric transducer in order to oscillate ink in the nozzle.
  • the preceding pulse controls the position of the ink meniscus in the nozzle and thereby the ink drop size.
  • the preceding and main pulses are of the same polarity.
  • these pulses are of opposite polarity.
  • This patent also mentions the control of ink drop size by changing the voltage and/or the pulse width of the preceding pulse and the time interval between the application of the preceding pulse and the main pulse.
  • Relatively complex drive circuitry has also been used to insert time delays in the application of drive signals applied to transducers to compensate for variations in travel time to the print medium.
  • this approach adds to the costs of such systems and can limit the maximum drop repetition rate of an ink jet.
  • U.S. Patent No. 3,060,429 of Winston discloses an ink jet print head having a nozzle which is supplied with ink under sufficient pressure to form a convex meniscus at the end of the nozzle, but which is insufficient to produce a flow of ink out of the nozzle.
  • An electrostatic field is established between the nozzle and a conductive platen. This electric field draws drops of ink from the nozzle toward strips of paper or other print medium placed against the platen. Drop ejection is interrupted by reducing the strength of the electric field.
  • an anode or valving plate with an aperture is positioned between the nozzle and platen.
  • the ink jet is controlled to interrupt the flow of ink toward the print medium.
  • deflecting electrodes are used to apply a field in a direction transverse to the direction of travel of ink drops toward the print medium so as to deflect or alter the travel path of the ink drops.
  • U.S. Patent No. 4,710,784 of Nakayama describes an ink jet print head which includes an array of electrically conductive printing electrodes impregnated with ink.
  • an electrical field of a first strength is established between such electrode and the print medium and printing does not occur.
  • a switch is operated to increase the strength of the field between the electrode and the print electrode. By increasing the length of the time period of application of the higher electric field, the volume of ink in a drop is increased.
  • the approach of the Nakayama patent adds to the circuit complexities by varying an electric field to accomplish drop ejection. Also, the Nakayama approach requires the individual switching of electric fields associated with each ink jet orifice. In addition, the benefits achieved by using acoustic drive mechanisms for generating pressure pulses in ink are not present in the Nakayama approach.
  • U.S. Patent No. 4,403,223 of Tsuzuki, et al. describes a drop-on-demand type ink jet printer in which a driving pulse is applied to a piezoelectric transducer to cause the ejection of a drop of ink from a nozzle.
  • the drop size is varied by controlling the energy content of the applied driving pulse for purposes of achieving half-tone printing.
  • the ejected ink drops pass between charging electrodes and are charged by a voltage which is applied as the drops are ejected from the nozzle. This charging voltage varies as a function of the energy content of the driving pulses.
  • the charged ink drops pass between deflection plates which generate a field oriented transversely to the direction of drop travel for purposes of altering the flight path of the drops.
  • the charged drops pass between a pair of plates 40 and a pair of plates 60, with the deflection plates positioned between plates 60 and plates 40.
  • the plates 40 and 60 establish an electric field oriented in the direction of travel of the ink drops for purposes of accelerating the drops.
  • the Tsuzuki, et al. patent requires relatively complex driving circuits inasmuch as the charging voltage is varied with variations in the driving pulse.
  • the use of deflection voltages also adds to the complexities of this device.
  • a drop-on-demand ink jet is described of the type having an ink chamber coupled to a source of ink, an ink drop forming orifice with an outlet, and in which the ink drop orifice is coupled to the ink chamber.
  • An acoustic driver is used to produce a pressure wave in the ink to cause the ink to pass outwardly through the ink drop orifice and the outlet.
  • a high voltage electric field is established and oriented to accelerate ink drops along a path from the outlet to print medium spaced from the outlet.
  • the acoustic driver causes ink to pass from the outlet and into the electric field whereupon the electric field pulls the ink from the outlet, assists in breaking off the ink passing from the outlet to form an ink drop, and assists in accelerating the ink drop toward the print medium.
  • the electric field remains time invariant during ink drop formation and drop acceleration. Preferably only one time invarient electric field is present along the path of ink drop travel.
  • the electric field may be established by one or more electrodes with the field being oriented to accelerate the drops in a common direction toward the print medium.
  • An ink jet of this type operated with an electric field in general is capable of producing a larger range of ink drop sizes, and in particular small size ink drops, than can be achieved by operating the ink jet without the electric field.
  • the ink jet of the present invention is simplified. For example, circuit complexities associated with varying an electric field during operation of an ink jet printer are eliminated.
  • the electric field allows stable and uniform operation of an ink jet printer at a higher drop repetition rate than the case without the electric field.
  • an acoustic driver may be operated to selectively vary the volume of ink that emerges from the outlet into the electric field.
  • the volume of ink in the ink drops traveling along the path toward the print medium is varied.
  • an acoustic driver imparts more energy to larger drops than smaller drops and tends to cause the larger drops to travel faster toward the print medium.
  • the electric field tends to accelerate smaller drops more than larger drops.
  • the combined effect from the use of an electric field and an acoustic driver is to cause the various volume ink drops to take substantially the same amount of time to travel to the print medium.
  • distortions in the resulting printed image are minimized and an effective approach for achieving grey scale or half-tone printing is achieved.
  • At least one bipolar electric pulse with refill and ejection pulse components of voltages of opposite polarity which are separated by a wait period, may be applied to acoustic drivers of the ink jet printer.
  • the volume of the ink in the ink drops is varied by selectively varying the duration of the wait period, varying the duration or pulse width of the ejection pulse component, varying the amplitude of the ejection pulse component, varying the ratio of the pulse width of the ejection pulse component to the pulse width of the refill pulse component, varying the ratio of the amplitude of the ejection pulse component to the amplitude of the refill pulse component, and by combinations of the above techniques.
  • a plurality of bipolar pulses are used to form the drops, with the number of pulses used to form an individual drop controlling the volume of ink in the drop.
  • Each of these bipolar electric pulses are separated from one another by a time period which is insufficient to permit the breaking off of an ink drop at the orifice outlet until a selected number of the bipolar drive pulses have been applied.
  • these bipolar electric pulses are separated from one another by a time period of at least about two times the duration of an individual bipolar electric pulse. More specifically, the bipolar electric pulses which are applied to form a single drop may be separated from one another by a time period of from about 40 microseconds to about 100 microseconds.
  • the acoustic drivers may be driven by unipolar electric pulses with the amplitude and pulse width of the unipolar pulses being varied to vary the volume of ink in the ink drops.
  • strings or packets of successive drive pulses may be used to vary the volume of ink in the ink drops.
  • the drop-on-demand ink jet printer may comprise an array of plural ink jets, each with an orifice or nozzle outlet.
  • a common electric field is established downstream (closer to the print medium) of the orifice outlets and is oriented in the direction of travel of ink drops ejected from the outlets.
  • the electric field pulls the ink passing from the outlets, assists in breaking off of the ink passing from the outlets to form ink drops, and accelerates the ink drops toward the print medium.
  • the present invention is useable with a wide variety of inks, including inks with a resistivity of from about 10 ⁇ 4 ohm-cm to 10 ⁇ 11 ohm-cm.
  • the inks may be of the phase change type as well as the type which is liquid at room temperature.
  • the magnitude of the electric field typically ranges from about 750 kilovolts per millimeter to the breakdown voltage across the gap between the electrodes which produce the field.
  • the present invention works for both positive and negative electric fields, however, a negative field appears to produce marginally improved results.
  • the strength of the electric field although remaining time invariant during drop formation and acceleration, may be varied from a first level for a first type of print medium to a second level for a second type of print medium. For example, if the print medium is mylar positioned between the electrodes forming the electric field, the electric field is typically higher than if the print medium is paper.
  • Another object of the present invention is to increase the range of drop sizes available from an ink jet printer.
  • a further object of the present invention is to provide an ink jet printer which is capable of stable operation at relatively high drop repetition rates.
  • Another object of the present invention is to reduce the drive voltages required to generate ink drops and to permit the operation of an ink jet print head in response to a wide range of drive wave forms.
  • Still another object of the present invention is to eliminate the complexities associated with establishing time varying electric fields during printing by an ink jet printer.
  • a drop-on-demand ink jet 10 is illustrated with an ink chamber 12 coupled to a source of ink 14.
  • the ink jet 10 has an orifice 16 coupled to or in communication with the ink chamber 12.
  • the orifice 16 has an outlet 18 through which ink passes during ink drop formation.
  • the ink drops travel in a first direction along a path from the outlet toward print medium 20, which is spaced from the outlet 18 by a gap G.
  • a typical ink jet printer includes a plurality of ink chambers each coupled to one or more respective orifices and orifice outlets.
  • a second orifice 18′ is indicated.
  • An acoustic drive mechanism 30 is utilized for generating a pressure wave in the ink to cause ink to pass outwardly through the ink drop orifice and outlet.
  • the illustrated acoustic drive mechanism comprises piezoceramic material 32 bonded to a thin diaphragm 34 which overlies and closes one side of the ink chamber 12.
  • the driver 30 bends in response to signals from a signal source 36 and causes pressure waves in the ink.
  • ink jet printers and acoustic drivers in conjunction with the present invention.
  • bubble jets having a heater for generating bubbles which cause a pressure wave in ink for generating ink drops may be used.
  • electromagnet-solenoid drivers as well as other shapes of piezoelectric drivers (e.g., circular, polygonal, cylindrical, annular-cylindrical, etc.) may be used.
  • various modes of deflection of piezoelectric drivers may also be used, such as bending mode, shear mode, and longitudinal mode.
  • a high voltage electric field is established and oriented to accelerate ink drops along the path of travel from the outlet 18 toward the print medium 20.
  • the electric field is constant or time invariant during drop formation and acceleration.
  • this electric field is preferrably the only electric field present along the path as the drops are formed and accelerated toward the print medium.
  • This time invarient field may be established by two, three, or more electrodes with the field being oriented to accelerate the drops in a common direction toward the print medium may be used. As a result, circuitry for charging drops and for establishing fields oriented to deflect drops away from the print medium is eliminated.
  • the orifice 16 extends through an orifice plate 38 which is shown coupled to the electrical ground potential.
  • a bar electrode 42 is positioned as shown with the print medium 20 between the electrode 42 and the orifice plate 38.
  • the electrode 42 is coupled to a power source S such that an electric field is established between the orifice plate 38 and the electrode 42.
  • This electric field is oriented in a direction which is orthogonal to the orifice plate 38 and thus parallel to the axes of the respective orifices 16.
  • a field oriented in this direction accelerates ink drops along the path from the outlets 18, 18′ etc. and toward the print medium.
  • the electric field which is downstream of the orifice plate 38, is typically established at 750 volts per millimeter as a minimum with 2000 volts per millimeter being a typical preferred field.
  • the field may be increased up to the breakdown voltage across the gap G, which typically occurs at about 3000-3500 volts per millimeter.
  • Various types of electrodes may be used to establish the desired electric field.
  • a ring or cylindrical electrode or electrodes may be used between the orifices and print medium for establishing the desired electric field with the ink drops passing through the ring electrodes.
  • an electrode 42′ may be positioned between the print medium 20 and the orifice plate 38. This type of electrode has an elongated slit 44 aligned with the orifice outlets 18, 18′ through which ink drops from the outlets travel to the print medium.
  • FIGS. 1 and 6 advantageously, although not necessarily, a common electric field is established for all of the ink jet orifices in an array. This further simplifies the present invention in that individualized fields and electrodes are not required for the various orifices and orifice outlets. As ink jet print heads become more and more compact, the spacing between individual orifice outlets is substantially reduced. By eliminating the need for individualized electric fields for the various ink jet outlets, the present invention is applicable to ink jet print heads with compact arrays of multiple nozzle orifices.
  • the electric field is time invariant or constant. That is, the electric field is not pulsed during operation of the ink jet nor is the magnitude of the electric field altered to charge individual ink drops or to adjust the acceleration applied to individual ink drops, depending, for example, upon their size.
  • the electric field is typically set at a lower level, such as about 2.5 kilovolts per millimeter.
  • the electric field need not be adjusted for variations in the print medium, but optimization of printing results can be achieved in the FIG. 1 approach by increasing the electric field as the dielectric constant of the print medium increases.
  • FIGS. 2a, 2b, 2c and 2d illustrate a sequence of ink drop ejection for the ink jet print head 10 of FIG. 1.
  • the ink meniscus 50 is withdrawn inside the orifice plate 38 and within the orifice 16 as shown in FIG. 2a. This is due to a slight negative pressure typically maintained in the ink chamber 12 to prevent drooling of ink from the orifice outlet 18 at times when drop ejection is not desired.
  • the ink meniscus 50 is in this position, there is no electric field on the surface of the meniscus because the orifice plate 38 is maintained at the electrical ground potential in this embodiment of the invention.
  • FIG. 2c shows this phenomena of a long narrow liquid filament 52 attached to a hemisphere-like base of ink near the ink orifice outlet.
  • the narrow liquid filament 52 breaks off from the meniscus tip as shown in FIG. 2d when the meniscus is pulled back inside of the orifice plate 38. This is believed to occur because, when the ink meniscus 50 is pulled back inside the ink orifice, the surface of the ink meniscus which includes the point of attachment to the filament 52 is not subjected to any electrostatic forces.
  • the acoustic driver 30 may be operated to simply push the meniscus out from the orifice plate and pull the meniscus back within the orifice plate with the electric field breaking off the filament and accelerating the filament toward the print medium.
  • the drive mechanism is used solely for this purpose and not for imparting the initial velocity to the ink drop, lower drive energy is required for driver 30 and a more compact ink jet print head can be used. This is the preferred mode of operation for producing drops of the smallest sizes.
  • the preferred approach for producing large volume drops involves the operation of the driver 30 with sufficient energy to form the drop and impart an initial small forward velocity to the drop.
  • drops of various volumes may be generated for use in half-tone or grey scale printing.
  • the energy from the drive mechanism primarily establishes the volume of the drop and also has a small influence on the initial velocity of the larger volume drops.
  • Typical initial velocities as a result of the drive pulse range up to about 2 meters per second, depending upon the drop size. Larger volume drops are accelerated by the drive mechanism at a faster rate than smaller volume drops, with the smallest drops not being accelerated by the drive pulse.
  • the electric field pulls the ink passing from the orifice outlet and accelerates these drops to typically from about 10 to about 20 meters per second.
  • the constant electric field accelerates the smaller drops at a faster rate than the larger drops.
  • the driver mechanism accelerates the large drops faster than the smaller drops. Therefore, the acoustic drive mechanism and electric field cooperate such that drops of various sizes require substantially the same amount of time to travel to the print medium.
  • the print medium is moved, the ink jet print head is moved to scan the print medium, or both the medium and ink jet print head move. Therefore, it is desirable not only to have a substantially constant travel time between the orifice plate and print medium, but also to have a much larger drop velocity in comparison to the relative media velocity, to minimize distortion in the resulting printed image.
  • a substantially constant travel time it is meant that the drops of various sizes reach the print medium within about plus or minus fifteen microseconds of one another.
  • ink jet print heads which stably operate uniformly at a first maximum drop repetition rate without an electric field are capable of operating at a higher drop repetition rate in the presence of a time invariant field in accordance with the present invention.
  • Ink jet print heads of the type shown in FIG. 1 have been operated at drop repetition rates of from up to eight kilohertz, with higher drop repetition rates being possible.
  • ink drops of smaller sizes have been obtained using a drop-on-demand ink jet print head operating in the presence of an electric field than the case of the ink jet print head operating without such a field for a given drop repetition rate. It has been found for ink jet print heads tested up to this time, that the minimum drop sizes can be reduced by about twenty percent or more by the use of an electric field.
  • the relatively high drop velocities achieved in the presence of an electric field permit greater versatility in the drive wave forms that can be used to drive acoustic drivers used in generating the drops at high drop repetition rates.
  • one of the principal advantages of the present invention relates to the effective achievement of half-tone or grey scale printing in a drop-on-demand ink jet printer when operated as described in the presence of an electric field.
  • grey scale printing is synonymous with drop volume modulation or variation.
  • the volume of ink contained in an individual ink drop is controlled by the diameter of the ink jet orifice and by controlling the wave form used in driving the acoustic driver.
  • the wave form By adjusting the wave form to increase the volume of ink and the amount of time the ink volume protrudes in front of the orifice outlet and in the region of the high electric field, larger ink drops can be achieved.
  • the volume of ink and the time the ink protrudes from the orifice outlet the smaller the ink drops.
  • a unipolar drive pulse is illustrated.
  • Such a unipolar drive pulse can be generated in a conventional manner by signal generator 36 and applied to the acoustic drive mechanism 30.
  • an amplitude modulation approach the amplitude of the pulse shown in FIG. 4 may be increased from V0 to V1. This results in an increase in the volume of ink included in an ink drop. Conversely, if the voltage is reduced from V0 to a lower level, the volume of ink in the ink drop is reduced.
  • a pulse width modulation technique may also be used. For example, by increasing the duration or pulse width of the pulse illustrated in FIG.
  • FIG. 3 One particularly advantageous drive signal for achieving grey scale printing is illustrated in FIG. 3.
  • This particular drive signal is a bipolar electric pulse 60 with a refill pulse component 62 and an ejection pulse component 64.
  • the components 62 and 64 are of voltages of opposite polarity.
  • the pulse components 62, 64 are also separated by a wait time period X.
  • the polarities of the components 62, 64 may be reversed from that shown in FIG. 3 depending upon the polarization of the piezoelectric driver mechanism 30.
  • the ink chamber 12 expands and draws ink into the chamber for refilling the chamber following the ejection of a drop.
  • the ink chamber begins to contract and moves the ink meniscus forwardly in the orifice 16 toward the orifice outlet 18.
  • the ink chamber is rapidly constricted to cause the ejection of a drop of ink.
  • the duration of the wait period increases, the ink meniscus moves closer to the orifice outlet 18 at the time the ejection pulse component 64 is applied.
  • the volume of ink included in an individual ink drop is increased. The volume is conversely reduced by shortening the wait period.
  • the duration of the desired wait period for a given drop volume depends upon the characteristics of the particular ink jet being utilized and can be observed by monitoring the performance of the ink jet. In general, the wait period is less than about one-third of the time period of the natural or resonance frequency of the meniscus. Typical meniscus resonance time periods range from 50 microseconds to 160 microseconds, depending upon the ink jet configuaration and the ink being used. In addition, by increasing the duration of the eject pulse component 64, or by increasing the amplitude of the eject pulse component the volume of the ink drops can be increased.
  • various levels or volumes of ink in individual ink drops were achieved by altering the drive wave form of FIG. 3.
  • the spots or dots FIG. 5 correspond to dots printed on mylar print medium which ranged in size from about 1.6 mils. to about 3.92 mils. If the ink is not melt ink, following fusing of the ink spots on the print medium, by the application of pressure, this varation in spot size is even greater, for example, from about 1.8 mils to about 5.5 mils.
  • the wait period X was set at 9 microseconds and the duration Y of the eject pulse component 64 was set at 3 microseconds.
  • X was set at 11 microseconds and Y was set at 5 microseconds.
  • X was set at 11 microseconds and Y at 9 microseconds.
  • X was set at 12 microseconds and Y was set at 11 microseconds.
  • X was set at 12 microseconds and Y was set at 15 microseconds.
  • X was set at 12 microseconds and Y was set at 20 microseconds.
  • the amplitude and pulse width of the refill pulse component was respectively five microseconds and forty volts. Also, the amplitude of the eject pulse component was forty volts. In addition, the electric field was 2.4 kilovolts per millimeter.
  • the ratio of the amplitude of the eject pulse component to the refill pulse component increases as does the volume of ink included in the drops.
  • the ratio of the pulse width of the eject pulse component to the pulse width of the refill pulse component also increases as does the ink drop volume.
  • bipolar pulses of the type shown in FIG. 3 may be utilized to produce an individual ink drop.
  • the volume of ink in the ink drop is increased.
  • each bipolar pulse causes the protrusion of an additional amount of ink into the electric field and thus increases the volume of ink included in an ink drop before the ink drop separates.
  • the time period between the bipolar pulses is increased.
  • Drop break-off can also be accomplished by applying a pulse of higher energy after the desired number of bipolar pulses have been used to generate the drop of the desired size.
  • the apparatus is simplified if all of the bipolar pulses have the same characteristics and the delay between individual bipolar pulses is simply adjusted to cause a drop to break off in the electric field.
  • a typical bipolar pulse of a string of such pulses has a duration of from about 20 microseconds to 40 microseconds.
  • the typical time delay between individual bipolar pulses ranges from about 12 to about 30 microseconds.
  • a suitable separation between the bipolar pulses is about 40 microseconds, that is about two times the duration of an individual bipolar pulse.
  • a successive bipolar pulse adds ink to the volume of an individual ink drop instead ofgenerating a separate drop.
  • a single bipolar pulse produced an ink dot on Xerox® bond paper of 2 mils in diameter
  • a string of two such bipolar pulses of 20 microsecond duration separated by a 40 microseconds produced an ink dot of 3 mils in diameter on this print medium
  • a string of three such bipolar pulses resulted in an ink dot of a diameter of 4 mils on the print medium.
  • the amplitude of the refill component of the individual bipolar pulses was forty volts.
  • the wait period between the refill and eject components was five microseconds.
  • the pulse width and amplitude of the eject pulse component of each bipolar drive pulse was, respectively, ten microseconds and forty volts.
  • the electric field was 1.6 kilovolts per millimeter.
  • the compounding of one or more bipolar pulses to produce an individual drop does reduce the maximum drop repetition rate at which an ink jet printer can be operated.
  • high drop repetition rates are still possible. For example, in the case above where up to three bipolar pulses were combined to produce the largest drop sizes, repetition rates of up to eight kilohertz have been achieved.
  • the present invention is applicable to ink jet printers using a wide variety of inks.
  • inks having a resistivity of from about 10 ⁇ 4 ohm-cm to about 10 ⁇ 11 ohm-cm would be suitable, with inks having a resistivity of about 10 ⁇ 6 ohm-cm to about 10 ⁇ 8 ohm-cm being more suitable.
  • higher resistivity inks are believed to produce better results, although the exact range of suitable resistivity has yet to be established.
  • Inks that are liquid at room temperature, as well as inks of the phase change type which are solid at room temperature may be used.
  • One suitable phase change ink is disclosed in European Patent Application No 89 307777.6. Again, however, the present invention is not limited to particular types of ink.
  • the invention provides a method of operating a drop-on-demand ink jet of the type having an ink chamber coupled to a source of ink, an ink drop orifice with an outlet, the ink drop orifice being coupled to the ink chamber, acoustic drive means for producing a pressure wave in the ink to cause ink to pass outwardly through the ink drop orifice and outlet and in which ink drops travel in a first direction along a path from the outlet, toward print medium spaced from the outlet and method comprising establishing a high voltage electric field oriented to accelerate ink drops along the path from the outlet toward the print medium, operating the acoustic drive means to cause ink to pass from the outlet and into the electric field, the electric field pulling the ink passing from the outlet, the electric field assisting in breaking off of ink passing from the outlet to form an ink drop, and the electric field accelerating the ink drop toward the print medium, and maintaining the electric field time invariant (and preferably as the only electric field present along the path
  • the operating step conveniently comprises operating the acoustic drive means to selectively vary the volume of ink that emerges from the outlet into the electric field and thereby the volume of ink drops travelling along the path toward the print medium, the electric field accelerating the various volume ink drops such that drops of various sizes require substantially the same amount of time to travel to the print medium, whereby the various volume drops are used to accomplish grey scale or half-tone printing.
  • the drive means may comprise a piezoelectric drive means for expanding and contracting the volume of the ink chamber, the operating step comprising the step of driving the driver with at least one bipolar electric pulse with refill and ejection pulse components of voltages of opposite polarity which are separated by a wait period, the operating step including varying the duration of the wait period to vary the volume of the ink drops.
  • the operating step may comprise the step of driving the driver with a bipolar electric pulse with refill and ejection pulse components of voltages of opposite polarity which are separated by a wait period, the operating step including varying the duration of the ejection pulse to vary the volume of the ink drops.
  • the operating step may comprise the step of driving the driver with a bipolar electric pulse with refill and ejection pulse components of voltages of opposite polarity which are separated by a wait period, the operating step including varying the duration of the wait period and the duration of the ejection pulse to vary the volume of the ink drops.
  • the operating step comprises the step of driving the driver with at least one bipolar electric pulse with refill and ejection pulse components of voltages of opposite polarity which are separated by a wait period, the operating step including varying the amplitude of the ejection pulse to vary the volume of the ink drops.
  • a further alternative comprises the step of driving the driver with at least one bipolar electric pulse with refill and ejection pulse components of voltages of opposite polarity which are separated by a wait period, the operating step including varying the ratio of the pulse duration of the ejection pulse component to the pulse width of the refill pulse component to vary the volume of ink drops or the step of driving the driver with at least one bipolar electric pulse with refill and ejection pulse components of voltages of opposite polarity which are separated by a wait period, the operating step including varying the ratio of the amplitude of the ejection pulse component to the amplitude of the refill pulse component to vary the volume of ink drops.
  • At least one unipolar electric pulse may be used instead of a bipolar pulse, the operating step including the step of varying the duration of unipolar drive pulses to vary the volume of ink in the ink drops, the step of varying the amplitude of the unipolar drive pulses to vary the volume of ink in the ink drops, or the step of varying the duration and the amplitude of the unipolar drive pulses to vary the volume of ink in the ink drops.
  • driving is effected with at least one bipolar electric pulse with refill and ejection pulse components of voltages of opposite polarity which are separated by a wait period, the operating step including the step of varying the number of bipolar pulses used to form the drops to vary the volume of ink in the ink drops.
EP19900313723 1989-12-15 1990-12-14 Method and apparatus for printing with a drop-on-demand ink jet print head using an electric field Ceased EP0437062A3 (en)

Applications Claiming Priority (2)

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US45108089A 1989-12-15 1989-12-15
US451080 1989-12-15

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EP0437062A3 EP0437062A3 (en) 1991-12-27

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JP (1) JPH07125193A (de)

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EP0562786A2 (de) * 1992-03-23 1993-09-29 Canon Kabushiki Kaisha Tintenstrahlaufzeichnungsvorrichtung und Verfahren zur Tintenablagedetektion
EP0575204A2 (de) * 1992-06-19 1993-12-22 Tektronix, Inc. Verfahren zum Betrieb eines Farbstrahls zum Erreichen einer hohen Druckqualität und einer hohen Druckrate
EP0608105A2 (de) * 1993-01-19 1994-07-27 Canon Kabushiki Kaisha Mehrfarbentintenstrahlaufzeichnungsvorrichtung
EP0608879A1 (de) * 1993-01-29 1994-08-03 Canon Kabushiki Kaisha Tintenstrahlgerät
EP0648606A2 (de) * 1993-10-19 1995-04-19 Tektronix, Inc. Auf Abruf arbeitender Tintenstrahlkopf und Verfahren
US5477249A (en) * 1991-10-17 1995-12-19 Minolta Camera Kabushiki Kaisha Apparatus and method for forming images by jetting recording liquid onto an image carrier by applying both vibrational energy and electrostatic energy
EP0832742A2 (de) * 1996-09-26 1998-04-01 Xerox Corporation Verfahren und Vorrichtung zum Bilden und Bewegen von Tintentröpfen
US5838349A (en) * 1994-06-17 1998-11-17 Natural Imaging Corporation Electrohydrodynamic ink jet printer and printing method
WO1998051504A1 (en) * 1997-05-15 1998-11-19 Xaar Technology Limited Operation of droplet deposition apparatus
US5963230A (en) * 1996-07-25 1999-10-05 Minolta Co., Ltd. Inkjet printer and inkjet printing method
US6030065A (en) * 1996-12-12 2000-02-29 Minolta Co., Ltd. Printing head and inkjet printer
US6036302A (en) * 1997-02-06 2000-03-14 Minolta Co., Ltd. Inkjet recording apparatus
US6036303A (en) * 1997-01-20 2000-03-14 Minolta Co., Ltd. Inkjet recording head for reducing crosstalk
US6042219A (en) * 1996-08-07 2000-03-28 Minolta Co., Ltd. Ink-jet recording head
US6053600A (en) * 1997-01-22 2000-04-25 Minolta Co., Ltd. Ink jet print head having homogeneous base plate and a method of manufacture
US6059395A (en) * 1997-01-22 2000-05-09 Minolta Co., Ltd. Inkjet recording head
US6109715A (en) * 1996-12-12 2000-08-29 Minolta Co., Ltd. Inkjet printer
US6123406A (en) * 1996-03-06 2000-09-26 Canon Kabushiki Kaisha Printer with residual ink detection
US6126263A (en) * 1996-11-25 2000-10-03 Minolta Co., Ltd. Inkjet printer for printing dots of various sizes
US6142607A (en) * 1996-08-07 2000-11-07 Minolta Co., Ltd. Ink-jet recording head
US6149260A (en) * 1997-01-21 2000-11-21 Minolta Co., Ltd. Ink jet recording apparatus capable of printing in multiple different dot sizes
US6174040B1 (en) 1997-01-31 2001-01-16 Minolta Co., Ltd. Inkjet printing head and inkjet printing head manufacturing method
US6290317B1 (en) 1997-02-06 2001-09-18 Minolta Co., Ltd. Inkjet printing apparatus
US6439696B1 (en) * 1999-10-12 2002-08-27 Canon Kabushiki Kaisha Ink jet printing apparatus, ink jet printing method and ink jet print head with control of drive voltage and pulse width
EP1780016A1 (de) * 2005-10-26 2007-05-02 Seiko Epson Corporation Flüssigkeitsausstossgerät, Aufzeichnungsgerät und Felderzeugende Einheit
CN1954998B (zh) * 2005-10-26 2010-05-26 精工爱普生株式会社 液体喷射设备、记录设备和场产生单元
US8210630B2 (en) 2005-06-24 2012-07-03 Kyocera Corporation Method for driving liquid ejector

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US5477249A (en) * 1991-10-17 1995-12-19 Minolta Camera Kabushiki Kaisha Apparatus and method for forming images by jetting recording liquid onto an image carrier by applying both vibrational energy and electrostatic energy
US5828393A (en) * 1991-10-17 1998-10-27 Minolta Co., Ltd. Ink jet head for jettting ink onto an ink carrier and an ink jet recording apparatus for forming an ink image onto an ink carrier
EP0562786A2 (de) * 1992-03-23 1993-09-29 Canon Kabushiki Kaisha Tintenstrahlaufzeichnungsvorrichtung und Verfahren zur Tintenablagedetektion
EP0562786A3 (en) * 1992-03-23 1994-06-01 Canon Kk Ink jet recording apparatus and ink discharge detecting method for said apparatus
US6048046A (en) * 1992-03-23 2000-04-11 Canon Kabushiki Kaisha Ink discharge detecting method for an ink jet recording apparatus, said ink jet recording apparatus and an image forming device using said ink jet recording apparatus
US6467868B2 (en) 1992-03-23 2002-10-22 Canon Kabushiki Kaisha Ink discharge detecting method for an ink jet recording apparatus, said ink jet recording apparatus, and an image forming device using said ink jet recording apparatus
US5508722A (en) * 1992-03-23 1996-04-16 Canon Kabushiki Kaisha Ink jet apparatus and method for detecting ink nondischarge based on ink temperature
EP0575204A2 (de) * 1992-06-19 1993-12-22 Tektronix, Inc. Verfahren zum Betrieb eines Farbstrahls zum Erreichen einer hohen Druckqualität und einer hohen Druckrate
EP0575204A3 (de) * 1992-06-19 1994-12-07 Tektronix Inc Verfahren zum Betrieb eines Farbstrahls zum Erreichen einer hohen Druckqualität und einer hohen Druckrate.
EP0608105A3 (de) * 1993-01-19 1995-02-08 Canon Kk Mehrfarbentintenstrahlaufzeichnungsvorrichtung.
EP0608105A2 (de) * 1993-01-19 1994-07-27 Canon Kabushiki Kaisha Mehrfarbentintenstrahlaufzeichnungsvorrichtung
US5903289A (en) * 1993-01-19 1999-05-11 Canon Kabushiki Kaisha Control circuit of a compact recording apparatus
EP0608879A1 (de) * 1993-01-29 1994-08-03 Canon Kabushiki Kaisha Tintenstrahlgerät
US5898446A (en) * 1993-01-29 1999-04-27 Canon Kabushiki Kaisha Acoustic ink jet head and ink jet recording apparatus having the same
EP0648606A3 (de) * 1993-10-19 1995-08-30 Tektronix Inc Auf Abruf arbeitender Tintenstrahlkopf und Verfahren.
EP0648606A2 (de) * 1993-10-19 1995-04-19 Tektronix, Inc. Auf Abruf arbeitender Tintenstrahlkopf und Verfahren
US5838349A (en) * 1994-06-17 1998-11-17 Natural Imaging Corporation Electrohydrodynamic ink jet printer and printing method
US6123406A (en) * 1996-03-06 2000-09-26 Canon Kabushiki Kaisha Printer with residual ink detection
US5963230A (en) * 1996-07-25 1999-10-05 Minolta Co., Ltd. Inkjet printer and inkjet printing method
US6042219A (en) * 1996-08-07 2000-03-28 Minolta Co., Ltd. Ink-jet recording head
US6142607A (en) * 1996-08-07 2000-11-07 Minolta Co., Ltd. Ink-jet recording head
US6513909B1 (en) 1996-09-26 2003-02-04 Xerox Corporation Method and apparatus for moving ink drops using an electric field and transfuse printing system using the same
EP0832742A3 (de) * 1996-09-26 1999-04-21 Xerox Corporation Verfahren und Vorrichtung zum Bilden und Bewegen von Tintentröpfen
EP0832742A2 (de) * 1996-09-26 1998-04-01 Xerox Corporation Verfahren und Vorrichtung zum Bilden und Bewegen von Tintentröpfen
US6126263A (en) * 1996-11-25 2000-10-03 Minolta Co., Ltd. Inkjet printer for printing dots of various sizes
US6030065A (en) * 1996-12-12 2000-02-29 Minolta Co., Ltd. Printing head and inkjet printer
US6109715A (en) * 1996-12-12 2000-08-29 Minolta Co., Ltd. Inkjet printer
US6036303A (en) * 1997-01-20 2000-03-14 Minolta Co., Ltd. Inkjet recording head for reducing crosstalk
US6149260A (en) * 1997-01-21 2000-11-21 Minolta Co., Ltd. Ink jet recording apparatus capable of printing in multiple different dot sizes
US6053600A (en) * 1997-01-22 2000-04-25 Minolta Co., Ltd. Ink jet print head having homogeneous base plate and a method of manufacture
US6059395A (en) * 1997-01-22 2000-05-09 Minolta Co., Ltd. Inkjet recording head
US6174040B1 (en) 1997-01-31 2001-01-16 Minolta Co., Ltd. Inkjet printing head and inkjet printing head manufacturing method
US6036302A (en) * 1997-02-06 2000-03-14 Minolta Co., Ltd. Inkjet recording apparatus
US6290317B1 (en) 1997-02-06 2001-09-18 Minolta Co., Ltd. Inkjet printing apparatus
US6281913B1 (en) 1997-05-15 2001-08-28 Xaar Technology Limited Operation of droplet deposition apparatus
WO1998051504A1 (en) * 1997-05-15 1998-11-19 Xaar Technology Limited Operation of droplet deposition apparatus
US6439696B1 (en) * 1999-10-12 2002-08-27 Canon Kabushiki Kaisha Ink jet printing apparatus, ink jet printing method and ink jet print head with control of drive voltage and pulse width
US8210630B2 (en) 2005-06-24 2012-07-03 Kyocera Corporation Method for driving liquid ejector
EP1780016A1 (de) * 2005-10-26 2007-05-02 Seiko Epson Corporation Flüssigkeitsausstossgerät, Aufzeichnungsgerät und Felderzeugende Einheit
CN1954998B (zh) * 2005-10-26 2010-05-26 精工爱普生株式会社 液体喷射设备、记录设备和场产生单元
US7735975B2 (en) 2005-10-26 2010-06-15 Seiko Epson Corporation Liquid ejecting apparatus, recording apparatus, and field generating unit
US8282195B2 (en) 2005-10-26 2012-10-09 Seiko Epson Corporation Liquid ejecting apparatus, recording apparatus, and field generating unit

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Publication number Publication date
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