EP0575204A2 - Méthode de commande d'un jet d'encre pour réaliser une haute qualité d'impression et un haut débit d'impression - Google Patents

Méthode de commande d'un jet d'encre pour réaliser une haute qualité d'impression et un haut débit d'impression Download PDF

Info

Publication number
EP0575204A2
EP0575204A2 EP93304838A EP93304838A EP0575204A2 EP 0575204 A2 EP0575204 A2 EP 0575204A2 EP 93304838 A EP93304838 A EP 93304838A EP 93304838 A EP93304838 A EP 93304838A EP 0575204 A2 EP0575204 A2 EP 0575204A2
Authority
EP
European Patent Office
Prior art keywords
ink
drop
pulse
ink jet
orifice
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP93304838A
Other languages
German (de)
English (en)
Other versions
EP0575204A3 (fr
Inventor
Douglas M. c/o Tektronix Inc. Stanley
Joy c/o Tektronix Inc. Roy
Susan C. c/o Tektronix Inc. Schoening
Jeffrey J. c/o Tektronix Inc. Anderson
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Tektronix Inc
Original Assignee
Tektronix Inc
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
Application filed by Tektronix Inc filed Critical Tektronix Inc
Publication of EP0575204A2 publication Critical patent/EP0575204A2/fr
Publication of EP0575204A3 publication Critical patent/EP0575204A3/fr
Withdrawn legal-status Critical Current

Links

Images

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
    • B41J2/135—Nozzles
    • B41J2/14—Structure thereof only for on-demand ink jet heads
    • B41J2/14201—Structure of print heads with piezoelectric elements
    • B41J2/14233—Structure of print heads with piezoelectric elements of film type, deformed by bending and disposed on a diaphragm
    • 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
    • B41J2/04516—Control methods or devices therefor, e.g. driver circuits, control circuits preventing formation of satellite drops
    • 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
    • B41J2/04581—Control methods or devices therefor, e.g. driver circuits, control circuits controlling heads based on piezoelectric elements
    • 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
    • B41J2/04588—Control methods or devices therefor, e.g. driver circuits, control circuits using a specific waveform
    • 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
    • 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
    • B41J2/04593—Dot-size modulation by changing the size of the drop

Definitions

  • the present invention relates to printing with a drop-on-demand ink jet print head, and, more specifically, primarily to various configurational and operational aspects of such printing which improves print quality and provides long periods of stable operation.
  • Ink jet printers in particular drop-on-demand ("DOD") ink jet printers having ink jet print heads with acoustic drivers for ink drop formation, are well known in the art.
  • the principle behind an ink jet print head of this type is the generation of a pressure wave in an ink chamber and the resultant subsequent emission of ink droplets from an ink pressure chamber through a nozzle orifice as a result of the pressure wave.
  • a wide variety of acoustic drivers is employed in ink jet print heads of this type.
  • the drivers may consist of a pressure transducer formed by a piezoelectric ceramic material bonded to a thin diaphragm. In response to an applied voltage, the piezoelectric ceramic material deforms and causes the diaphragm to displace ink in the ink pressure chamber, which displacement results in a pressure wave and the flow of ink through one or more nozzles.
  • Piezoelectric drivers may be of any suitable shape such as circular, polygonal, cylindrical, and annular-cylindrical. 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 jet print heads) 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 independently driven by an associated acoustic driver.
  • U.S. Patent No. 4,523,200 to Howkins describes one approach to operating an ink jet print head with the purpose of achieving high velocity ink drops free of satellites and orifice puddling and providing stabilized ink jet print head operation.
  • an electromechanical transducer is coupled to an ink chamber and is driven by a composite signal including independent successive first and second electrical pulses of opposite polarity in one case and sometimes separated by a time delay.
  • the first electrical pulse is an ejection pulse with a pulse width which is substantially greater than that of the second pulse.
  • the illustrated second pulse in the case where the pulses are of opposite polarity has an exponentially decaying trailing edge.
  • the application of the first pulse causes a rapid contraction of the ink chamber of the ink jet print head and initiates the ejection of an ink drop from the associated orifice.
  • the application of the second pulse causes rapid volume expansion of the ink chamber and produces early break-off of an ink drop from the orifice.
  • drop volume can be selected to provide optimum spot size 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 to Murakami, et al. discloses an approach for operating an ink jet print head with the purpose of achieving different size drops on print media, such as desired 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 energy contained in the voltage pulse is below the threshold necessary to eject a drop.
  • the preceding pulse controls the position of the ink meniscus in the nozzle and thereby the ink drop size.
  • 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 halftone 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.
  • Another object of the present invention is to provide an improved ink jet print head which is capable of selectively producing ink drops of varying sizes.
  • 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.
  • the driver is operated to expand and contract the ink chamber to eject a drop of ink from the ink drop ejecting orifice outlet with the volume of the ink chamber first being expanded to refill the chamber with ink from a source of ink.
  • ink is also withdrawn within the orifice toward the ink chamber and away from the ink drop ejection orifice outlet.
  • a wait period is then established during which time the ink chamber is returning back to its original volume and the ink in the orifice to advance within the orifice away from the ink chamber and toward the ink drop ejection orifice outlet.
  • the driver is then operated to contract the volume of the ink chamber to eject a drop of ink.
  • each of the waiting steps comprises the step of waiting until the ink in the orifice advances to substantially the same position within the orifice to which the ink advances during the other waiting steps before the ink chamber is contracted to eject an ink drop.
  • the waiting step comprises the step of waiting until the ink advances to a position substantially at the ink drop ejection orifice outlet, but not beyond such orifice outlet, before contracting the volume of the ink chamber to eject a drop of ink.
  • the contracting step occurs at a time when the ink is advancing toward that is, has a forward component of motion toward, the ink drop ejection orifice outlet.
  • the driver may comprise a piezoelectric driver which is driven by a drive pulse including first and second pulse components separated by a wait period, the first and second pulse components being of an opposite polarity.
  • These pulse components or electric drive pulses may be of a square wave or trapezoidal wave form.
  • the acoustic driver Upon application of a first voltage pulse, called the "refill pulse component," the acoustic driver operates to increase the volume of the ink pressure chamber through chamber expansion to refill the chamber with ink from the ink source. During ink pressure chamber expansion, ink is also drawn back within the orifice toward the ink pressure chamber and away from the orifice outlet. When the refill pulse component is no longer applied, a wait period state is then established during which time the ink pressure chamber returns to its original volume and the ink in the orifice advances within the orifice away from the ink pressure chamber and toward the orifice outlet.
  • the acoustic driver Upon application of a second voltage pulse of opposite relative polarity, called the "ejection pulse component," the acoustic driver then operates to reduce the volume of the ink pressure chamber through chamber contraction to eject a drop of ink.
  • a sequence of ink pressure chamber expansion, a wait period, and ink pressure chamber contraction accomplishes the ejection of ink drops.
  • the refill pulse component, followed by the wait period state and the ejection pulse component comprise the drive signal.
  • the refill pulse component and the ejection pulse component may be of square wave or trapezoidal wave form.
  • a preferred embodiment of the drive signal comprises a bipolar electrical signal with refill and ejection pulse components varying about a zero amplitude reference voltage maintained during the wait period state; however, skilled persons would appreciate that the reference voltage need not have zero voltage amplitude.
  • the drive signal may comprise pulse components of opposite relative polarity varying about a positive or negative reference voltage amplitude maintained during the wait period state.
  • the drive signal is also tuned to the characteristics of the ink jet print head to avoid the presence of high energy components at the dominant acoustic resonant frequency of the ink jet print head, which may be determined in a known manner.
  • the most significant factor affecting the dominant acoustic resonant frequency of the ink jet is the resonant frequency of the ink meniscus.
  • Another significant factor affecting the print head dominant acoustic resonant frequency is the length of ink passage from the outlet of the ink pressure chamber to the orifice outlet of the ink jet, called the "offset channel". The energy content of the complete electric drive pulse at various frequencies is also determined.
  • the complete electric drive pulse in this case includes the refill pulse components, the drive pulse components, and wait periods utilized in ejecting a drop of ink.
  • the drive pulse is then adjusted such that a minimum energy content of the drive pulse exists at the dominant acoustic resonance frequency of the ink jet. If an ink jet of the type having an offset channel between the ink chamber and the ink drop ejection orifice outlet is used, the dominant acoustic resonance frequency corresponds to the standing wave resonance frequency through liquid ink in the offset channel of the ink jet. With this approach, the drive signal is tuned to the characteristics of the ink jet to avoid high energy components at the dominant resonance frequency of the ink jet.
  • the drive signal is preferably tuned to the characteristics of the ink jet print head by adjusting the time duration of the wait period state and the time duration of the first or refill pulse component, including the rise time and fall time of the refill pulse component.
  • the rise time and fall time for the refill pulse component is the transition time from zero voltage to the voltage amplitude of the refill pulse component and from the voltage amplitude of the refill pulse component to zero voltage, respectively.
  • a standard spectrum analyzer may be used to determine the energy content of the drive signal at various frequencies. After a tuning adjustment, a minimum energy content of the drive signal coincides with the dominant acoustic resonant frequency of the ink jet print head.
  • the drive pulse may be adjusted, if necessary, such that the minimum energy content of the drive pulse at a frequency which substantially corresponds to the dominant acoustic frequency of the ink jet is at least about 20 db below the maximum energy content of the drive pulse at frequencies other than the frequency which substantially corresponds to the dominant acoustic resonance frequency.
  • the drive pulse may be adjusted, such that the maximum energy content of the drive pulse does not occur at a frequency which is sufficiently close (for example, less than 10 KHz) to any of the major resonance frequencies of the ink jet print head.
  • These major resonance frequencies include the meniscus resonance frequency, Helmholtz resonance frequency, piezoelectric drive resonance frequency and various acoustic resonance frequencies of the different channels and passageways forming the ink jet print head.
  • the drive pulse may have refill and ejection pulse components of a trapezoidal shape in which the pulse components have a different rate of rise to their maximum amplitude than the rate of fall from the maximum amplitude.
  • the first electric drive pulse or refill pulse component may have a rise time from about 1 to about 4 microseconds, be at a maximum amplitude for from about 2 to about 7 microseconds, and may have a fall time from about 1 to about 7 microseconds.
  • the wait period may be greater than about 8 microseconds.
  • the second electric drive or eject pulse component may be within the same range of rise time, time at a maximum amplitude and fall time as the first electric drive pulse, but of opposite polarity.
  • the rise time of the first and second electric drive pulse component may more preferably be from about 1 to about 2 microseconds, the first and second electric drive pulse component may be at its maximum amplitude for from about 4 to about 5 microseconds, and the first and second electric drive pulse may have a fall time of from about 2 to about 4 microseconds, with the wait period being from about 15 to about 22 microseconds.
  • a significant advantage of the present invention is that the improved ink jet print head is capable of producing ink drops requiring a substantially uniform travel time to reach print media over a wide range of drop repetition or ejection rates. This directly affects the quality of the resulting printing.
  • a drop-on-demand ink jet printer incorporating the various aspects of the present invention may comprise an array of ink jets, each with an orifice or nozzle outlet.
  • Another primary aspect of the present invention provides a technique of controlling the drive electrical pulse applied to the acoustic driver in order to selectively vary the volume of ink in the ink drops ejected through the individual ink jets.
  • the volume of the ink drop is controlled by controlling one or more characteristics of at least one bipolar electric pulse applied to acoustic drivers of the ink jet printer, with refill and ejection pulse components having voltages of opposite polarity that are separated by a wait period.
  • 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 driving pulses are also configured to limit the maximum negative pressure within the ink jet chambers to a value that is less than a predetermined threshold limit in order to avoid adverse effects of rectified diffusion. Excessive, repeated negative pressure pulses can cause air bubbles within the ink to grow to the point of affecting print quality and the eventual failure of operation of an ink jet.
  • Serial No. 07/665,615 (EPA 91 306471.3) is to be referenced for a description of driving signal pulse shapes that avoids problems of rectified diffusion.
  • This disclosure also appears in corresponding European patent application publication no. 467,656 dated January 22, 1992, which is incorporated herein by this reference.
  • the present invention relates to a method including the above aspects individually and in combination with one another. Portions of this are disclosed in European patent application publication no. 437,106, dated July 17, 1991, corresponding to the aforementioned parent United States application Serial No. 461,860. This published European application is incorporated herein by this reference.
  • FIG. 1 is a schematic illustration of one form of an ink jet print head in accordance with the present invention with print media shown spaced from the ink jet print head.
  • FIG. 2 illustrates a form of drive signal for an acoustic driver of an ink jet print head in accordance with the present invention.
  • FIG. 3 is a schematic illustration, in section, of one type of ink jet print head which is capable of being operated in accordance with the method of the present invention.
  • FIGS. 4a, 4b and 4c illustrate a simulation of the change in shape of an ejected ink column at a point near breakoff of an ink drop from the column when an ink jet print head of the FIG. 3 form is actuated by a single drive pulse of the type shown in FIG. 2 and with the wait period for such pulse being varied.
  • FIG. 5 is a plot of drop flight time versus drop ejection rate for the continuous operation of an ink jet print head of the type illustrated in FIG. 3 when actuated by the drive wave form of FIG. 2, where the eject pulse width has been optimized.
  • FIG. 6 is a plot of the drop flight time as a function of drop ejection rate for the continuous operation of an ink jet of the type illustrated in FIG. 3 actuated by a drive pulse having only the eject pulse component "C" of the wave form of FIG. 2 and in which the eject pulse has been optimized for a specific ink jet print head.
  • FIG. 7 illustrates another drive signal for an acoustic driver of an ink jet printer in accordance with the present invention.
  • FIG. 8 is an electronic block diagram of a signal source that generates the bipolar drive signal shown in FIG. 7.
  • FIG. 9 shows yet another drive signal for an acoustic driver of an ink jet printer.
  • a drop-on-demand ink jet print head 9 is illustrated with an internal ink pressure chamber (not shown in this figure) coupled to a source of ink 11.
  • the ink jet print head 9 has one or more orifice outlets 14, 14a, 14b, etc. coupled to or in communication with the ink chamber by way of an ink orifice. Ink passes through the orifice outlets during ink drop formation. The ink drops travel in a first direction along a path from the orifice outlets toward print medium 13, which is spaced from the orifice outlets.
  • a typical ink jet printer includes a plurality of ink chambers each coupled to one or more of the respective orifices and orifice outlets.
  • An acoustic drive mechanism 36 is utilized for generating a pressure wave or pulse, which is applied to the ink residing within the ink pressure chamber to cause ink to pass outwardly through the orifice and associated outlet 14.
  • the acoustic driver 36 operates in response to signals from a signal source 37 to cause the pressure waves to be applied to the ink.
  • the invention has particular applicability and benefits when piezoelectric ceramic drivers are used in ink drop formation.
  • One preferred form of an ink jet print head using this type of acoustic driver is described in detail in US patent no. 5,087,930, incorporated herein by this reference.
  • 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.
  • one form of ink jet print head 9 in accordance with the disclosure of the above-identified patent no. 5,087,930 has a body 10 which defines an ink inlet 12 through which ink is delivered to the ink jet print head.
  • the body also defines an ink drop forming orifice outlet or nozzle 14 together with an ink flow path from the ink inlet 12 to the nozzle 14.
  • an ink jet print head of this type would preferably include an array of nozzles 14 which are proximately disposed, that is closely spaced from one another, for use in printing drops of ink onto a print medium.
  • a typical color ink jet print head has at least four such manifolds for receiving, respectively, black, cyan, magenta, and yellow ink for use in black plus three color subtraction printing.
  • the number of such ink supply manifolds may be varied depending upon whether a printer is designed to print solely in black ink or with less than a full range of color.
  • ink flows through an ink inlet channel 18, through an ink inlet 20 and into an ink pressure chamber 22.
  • Ink leaves the ink pressure chamber 22 by way of an ink pressure chamber outlet 24 and flows through an ink passage 26 to the nozzle 14 from whicn ink drops are ejected.
  • Arrows 28 diagram this ink flow path.
  • the ink pressure chamber 22 is bounded on one side by a flexible diaphragm 34.
  • the pressure transducer in this case a piezoelectric ceramic disc 36 secured to the diaphragm 34, as by epoxy, overlays the ink pressure chamber 22.
  • the piezoelectric ceramic disc 36 has metal film layers 38 to which an electronic circuit driver, not shown in FIG. 3, but indicated at 37 in FIG. 1, is electrically connected.
  • the illustrated transducer is operated in its bending mode. That is, when a voltage is applied across the piezoelectric disc, the disc attempts to change its dimensions. However, because it is securely and rigidly attached to the diaphragm 34, bending occurs.
  • an optional ink outlet or purging channel 42 is also defined by the body 10 of the ink jet print head 9.
  • the purging channel 42 is coupled to the ink passage 26 at a location adjacent to, but interior to, the nozzle 14.
  • the purging channel 42 communicates from ink passage 26 to an outlet or purging manifold 44 which is connected by a purging outlet passage 46 to a purging outlet port 48.
  • the purging manifold 44 is typically connected by similar purging channels 42 to similar ink passages 26 associated with multiple nozzles 14.
  • ink flows in a direction indicated by arrows 50, through purging channel 42, purging manifold 44, purging outlet passage 46 and to the purging outlet port 48.
  • the body 10 is preferably formed of plural laminated plates or sheets, such as of stainless steel. These sheets are stacked in a superposed relationship.
  • these sheets or plates include a diaphragm plate 60, which forms the diaphragm and also defines the ink inlet 12 and purging outlet 48; an ink pressure chamber plate 62, which defines the ink pressure chamber 22, a portion of the ink supply manifold, and a portion of the purging passage 48; a separator plate 64, which defines a portion of the ink passage 26, bounds one side of the ink pressure chamber 22, defines the inlet 20 and outlet 24 to the ink pressure chamber, defines a portion of the ink supply manifold 16 and also defines a portion of the purging passage 46; an ink inlet plate 66, which defines a portion of the passage 26, the inlet channel 18, and a portion of the purging passage 46; another separator plate 68 which defines portions of the passage
  • More or fewer plates than illustrated may be used to define the various ink flow passageways, manifolds and pressure chambers.
  • multiple plates may be used to define an ink pressure chamber instead of a single plate as illustrated in FIG. 3.
  • not all of the various features need be in separate sheets or layers of metal.
  • Exemplary dimensions for elements of the ink jet print head of FIG. 3 are set forth in Table 1 below.
  • Table 1 Representative Dimensions and Resonant Characteristics For Figure 3 Ink Jet Print Heads Feature Cross Section Length Frequency of Resonance Ink Supply Channel 18 0.008''x0.010'' 0.268'' 60-70KHz Diaphragm Plate 60 0.110''dia. 0.004'' 160-180KHz Body Chamber 22 0.110''dia.
  • the various layers forming the ink jet print head may be aligned and bonded in any suitable manner, including by the use of suitable mechanical fasteners.
  • suitable mechanical fasteners include aluminum, copper, copper, and zinc.
  • one approach for bonding the metal layers is described in U.S. Patent No. 4,883,219 to Anderson, et al., and entitled "Manufacture of Ink Jet Print Heads by Diffusion Bonding and Brazing.”
  • FIG. 2 an advantageous drive signal for driving ink jets utilizing acoustic drivers is illustrated in FIG. 2.
  • This particular drive signal is a bipolar electrical pulse 100 with a refill pulse component 102 and an ejection pulse component 104.
  • the components 102 and 104 are voltages of opposite relative polarity of possibly different voltage amplitudes.
  • These electrical pulses or pulse components 102, 104 are also separated by a wait period state indicated at 106.
  • the time duration of the wait period 106 is indicated as "B" in FIG. 2.
  • the relative polarities of the pulse components 102, 104 may be reversed from that shown in FIG. 2, depending upon the polarization of the piezoelectric ceramic driver mechanism 36 (FIG. 1).
  • FIG. 2 demonstrates the representative shape of the drive signal, but does not provide representative values for the various attributes of the signal or its pulse components, such as voltage amplitudes, time durations or rise times and fall times. Furthermore, although the pulse components of the drive signal shown in FIG. 2 have trapezoidal or square wave form, in actual operation these pulse components may exhibit exponentially rising leading edges and exponentially decaying trailing edges.
  • a preferred embodiment of the drive signal comprises a bipolar electrical signal with refill and ejection pulse components varying about a zero voltage amplitude maintained during the wait period 106; however, the invention is not limited to this particular embodiment.
  • the drive signal may comprise pulse components of opposite relative polarity varying about a positive or negative reference voltage amplitude maintained during the wait period state.
  • the ink pressure chamber 22 expands upon the application of the refill pulse component 102 and draws ink into the ink pressure chamber 22 from the ink source 11 to refill the ink pressure chamber 22 following the ejection of a drop.
  • the ink pressure chamber 22 begins to contract and moves the ink meniscus forward in the ink orifice 103 (FIG. 3) toward the orifice outlet 14.
  • the ink meniscus continues toward the orifice outlet 14.
  • the ink pressure chamber 22 is rapidly constricted to cause the ejection of a drop of ink.
  • the ink meniscus is once again drawn back into the ink orifice 103 away from the orifice outlet 14 as a result of the application of the refill pulse component 102.
  • the time duration of the refill pulse component is less than the time required for the ink meniscus to return to a position adjacent to the orifice outlet 14 for ejection of a drop of ink.
  • the time duration of the refill pulse component 102 is less than one-half of the time period associated with the resonant frequency of the ink meniscus. More preferably, this duration is less than about one-fifth of the time period associated with the resonant frequency of the ink meniscus.
  • the resonant frequency of an ink meniscus in an orifice of an ink jet print head can be easily calculated from the properties of the ink, including the volume of the ink inside the ink jet print head, and the dimensions of the orifice in a known manner.
  • the time duration of the wait period "B" increases, the ink meniscus moves closer to the orifice outlet 14 at the time the ejection pulse component 104 is applied.
  • the time duration of the wait period 106 and of the ejection pulse component 104 is less than about one-half of the time period associated with the resonant frequency of the ink meniscus.
  • typical time periods associated with the resonant frequency of the ink meniscus range from about 50 microseconds to about 160 microseconds, depending upon the configuration of the specific ink jet print head and the particular ink.
  • the pulse components 102 and 104 of the drive signal controlling the operation of the ink jet print head to achieve high print quality and high printing rates are shown in FIG. 2 as being generally trapezoidal and of 5 opposite polarity. Square wave pulse components may also be used. A conventional signal source 37 may be used to generate pulses of this shape. Other pulse shapes may also be used.
  • a suitable refill pulse component 102 is one which results in increasing the volume of the ink pressure chamber 22 through the expansion of the chamber to refill the chamber with ink from the ink source 11 while withdrawing the ink in the ink orifice 103 back toward the ink pressure chamber 22 and away from the orifice outlet 14.
  • the wait period 106 is a period during which essentially zero voltage is applied to the acoustic driver.
  • the ejection pulse component 104 is of a shape which causes a rapid contraction of the ink pressure chamber 22 following the wait period 106 to reduce the volume of the chamber and eject a drop of ink.
  • a drive signal composed of pulses of the form shown in FIG. 2 is repeatedly applied to cause the ejection of ink drops.
  • One or more such pulses may be applied to cause the formation of each drop, but, in a preferred embodiment, at least one such composite drive signal is used to form each of the drops.
  • the time duration of the wait period 106 is typically set to allow the ink meniscus in the ink orifice 103 to advance to substantially the same position within the orifice during each wait period before contraction of the ink pressure chamber 22 to eject a drop.
  • the ink which was retracted during the refill pulse component is allowed to return to a location adjacent to the orifice outlet 14 prior to the arrival of the drop ejection pressure pulse as a result of pulse component 104.
  • the duration of the wait period is preferably established to allow the ink meniscus to advance within orifice 103 to a position substantially at the ink drop ejection orifice outlet 14, but not beyond such orifice outlet, before the ink chamber 22 is contracted to eject a drop of ink.
  • ink is allowed to project beyond the orifice outlet 14 for a substantial period of time before the ejection pulse 104 is applied, it may wet the surface surrounding the orifice outlet. This wetting may cause an asymmetric deflection of ink drops and non-uniform drop formation as the various drops are formed and ejected.
  • uniformity of drop flight time to the print medium is enhanced over a wide range of drop ejection rates.
  • the ink meniscus have a remnant of forward velocity within the orifice 103 toward orifice outlet 14 at the time of arrival of the pressure pulse in response to the ejection pulse component 104 of FIG. 2.
  • the eject pulse component 104 causes the diaphragm 34 of the pressure transducer to rapidly move inwardly toward the ink chamber 22 and results in a sudden pressure wave. This pressure wave ejects the drop of ink presented at the orifice outlet at the end of the wait period.
  • diaphragm returns toward its original position and, in so doing, initiates a negative pressure wave which assists in breaking off an ink drop.
  • Exemplary durations of the various pulse components for achieving high print quality and high printing rates are 5 microseconds for the "A" portion of the refill pulse component 102, with rise and fall times of respectively 1 microsecond and 3 microseconds; a wait period "B" of 15 microseconds; and an ejection pulse component 104 with a "C” portion of 5 microseconds and with rise and fall times like those of the refill pulse component 102.
  • FIG. 2 demonstrates the representative shape of the drive signal, but does not provide representative values for its various attributes. To achieve high print quality and high printing rates, it may sometimes be advantageous to reduce the duration of these time periods so that the fluidic system may be reinitialized as quickly as possible, thereby making faster printing rates possible.
  • An alternative method to increase the drop repetition rate for the drive signal comprises reducing the time duration from the trailing edge of the ejection pulse component to the leading edge of the refill pulse component. This method has the advantage that it does not affect the time durations of the pulse components, including rise and fall times.
  • FIG. 4 illustrates a simulation of the change in shape of an ejected ink column when an ink jet print head of the type illustrated in FIG. 3 is actuated by a drive signal composed of the exemplary durations above.
  • FIGS. 4a, 4b, and 4c demonstrate the effect of varying the wait period 106.
  • the main volume of ink 120 forms a spherical head which is connected to a long tapering tail 122 with drop breakoff occurring at a location 124 between the tail of this filament and the orifice outlet 14.
  • the tail 122 After drop breakoff, the tail 122 starts to coalesce into the head 120 and does not form a spherical drop by the time it reaches the print medium. However, due to the relatively high speed of the ink column with respect to the print medium the resulting spot on the print medium is nearly spherical.
  • the drop breakoff point 124 is adjacent to the main volume of ink 120 and results in a cleanly formed drop.
  • the tail 122 of the drop breaks off subsequently to the orifice outlet 14 and forms a satellite drop which moves at a relatively smaller velocity than that of the main drop. Consequently, the main drop 120 and satellite drop 122 form two separate spots on the print medium.
  • the drop breakoff point 124 occurs adjacent to the main drop volume 120.
  • the remaining ink filament 122 has weak points, indicated at 126 and 128, corresponding to potential locations at which the filament may break off and form satellite drops.
  • FIG. 4 illustrations are the result of a theoretical model of the operation of the ink jet print head of FIG. 3 using the form of the drive signal shown in FIG. 2.
  • the FIG. 4 illustrations show only the upper half of the formed drop above the center line of the ink orifice 103 in each of these figures.
  • a pull back or refill pulse such as pulse component 102 alone, nor an ejection pulse, such as component 104 alone, results in satisfactory print performance, even though drop ejection may be accomplished by either of the pulse components 104, 106 alone.
  • using just a refill pulse component 104 would tend to severely limit the drop ejection speed, such as to about 3.5 meters per seconds or less.
  • increasing the magnitude or duration of the refill pulse component 104 in an attempt to increase drop speed, would result in pulling the meniscus so far into the upstream edge of the ink orifice 103 that ingestion of air bubbles may result.
  • High drop speeds are desirable, such as on the order of 6 meters per second or more, to increase the capacity of an ink jet printer to operate at high drop ejection rates.
  • an eject pulse component 104 only results in a rhythmical variation in drop speed with changing drop ejection rates.
  • the frequency of the rhythmical variations may be verified from the information in Table 1 above to be the same as that of the reverberation resonance in the channel sections forming the ink flow path between the ink chamber 22 and the ink orifice outlet 14.
  • an eject pulse component only drive signal may be designed which smoothes the speed or flight time variations by using a drive pulse with a frequency spectrum which deliberately removes energy from the reverberations. However, in this case, the ink volume per drop declines as the ejection rate increases.
  • the ink chamber does not adequately refill between drop ejections at all drop ejection rates.
  • a further disadvantage is that, since the same amount of energy is imparted by the piezoelectric element to every drop ejected regardless of refilling, the smaller drops tend to travel at faster speeds. Thus, as shown in FIG. 6, the drop speed generally increases (corresponding to a decrease in flight drop time) as the drop ejection rate increases, although the rhythmical drop speed variations are absent.
  • the deficiencies of the eject only pulse component drive approach are overcome by actuating a refill pulse component 104 first to actively refill the ink chamber 22.
  • the offset channel 71 in FIG. 3 is also refilled if the ink jet print head is of a design having such a channel.
  • the ink chamber may be passively refilled fully by enlarging the ink inlet 18, 20 from the ink supply reservoir (11 in FIG. 1), without using an active refill pulse component 104.
  • the pressure pulse set up in the ink chamber 22 would flow into the conduit leading to the orifice 26 and also into the ink inlet 18, 20 itself.
  • the portion of the pressure wave traveling into the ink inlet would then represent energy unavailable for the ink drop formation.
  • the use of an active refill pulse component permits a smaller inlet opening 20 which reduces this potential loss of energy available for drop formation and also isolates the body chamber 22 and passageway 26 from pressure pulse disturbances originating in the ink reservoir or manifold 16 if the jet is a member of an array. This isolation is progressively reduced as the inlet opening 20 is enlarged. A balance is thus struck among the size of the ink inlet 20, the strength of the refill pulse component 102 (FIG. 2) and the strength of the eject pulse component 104. A strong refill pulse component 102 will pull ink through the inlet opening 20 into the pressure chamber 22.
  • Too strong of a refill pulse component will cause the ingestion of a bubble through the orifice outlet.
  • too strong of an eject pulse component 104 will eject more ink in a single drop than the refill pulse component may be able to draw through the ink inlet 20.
  • One preferred interrelationship of these parameters is described in Table 1 above and in the exemplary pulse component durations mentioned above.
  • a refill pulse component 102 in the drive signal tends to draw ink back from the external surface surrounding the ink orifice outlet 14. This action minimizes the possibility of ink wetting the surface surrounding the outlet and distorting the travel or breakoff of ink drops at the orifice outlet.
  • the preferred time duration of the wait period "B" is a combined function of the time for the retracted ink meniscus in ink orifice 103 to reach the orifice outlet 14 and the velocity of the ink at the instant of arrival of the pressure pulse initiated by the ejection pulse component 104. It is desired that the retracted ink meniscus reach the orifice outlet 14 with waning velocity just before the pressure pulse from the ejection pulse component 104 is applied.
  • FIG. 5 depicts the situation in which the ink jet print head is operated in the manner described to achieve high print quality and high printing rates.
  • the print medium was 1 mm. from the ink jet print head orifice outlet 14, and drop speeds in excess of 6 meters per second were achieved.
  • a maximum deviation of 30 microseconds was observed over an ink jet drop ejection rate ranging from 1,000 drops per second to 10,000 drops per second.
  • the drop speeds are relatively fast with uniform drop sizes being available.
  • the drop trajectories are substantially perpendicular to the orifice face plate for all drop ejection rates, inasmuch as the refill pulse component 102 of the drive pulse assists in reducing wetting of the external surface surrounding the orifice outlet 14 which may cause a deflection of the ejected drops from a desired trajectory.
  • satellite drop formation is minimized because this drive signal allows high viscosity ink, such as hot melt ink, within the conduit of the ink orifice 103 to behave as an intracavity acoustic absorber of pressure pulses reverberating in the offset channel 71 of an ink jet print head of the type shown in FIG. 3.
  • the relatively simple drive signal of the type illustrated in FIG. 2 may be achieved with conventional off-the-shelf digital electronic drive signal sources.
  • a preferred relationship between the drive pulse components 102, 104 and 106 have been experimentally determined.
  • a wait time period of at least about and preferably greater than about 8 microseconds
  • uniform and consistent ink drop formation has been achieved.
  • Shorter wait periods have been observed in some cases to increase the probability of formation of satellite drops than with the wait period established at or above this 8 microsecond level.
  • the refill or expanding pulse component 102 is no more than about 16 to 20 microseconds. A greater refill pulse component duration increases the possibility of ingesting bubbles into the ink orifice outlet.
  • the refill pulse component duration need be no longer than necessary to replace the ink ejected during ink drop formation. In general, shorter refill periods increase the drop repetition rate which may be achieved.
  • the refill pulse component 102 has a duration in a preferred form of no less than about 7 microseconds.
  • the duration of the ejection pulse component 104 is typically no more than about 16 to 20 microseconds and no less than about 6 microseconds. Again, pulse components within these ranges enhances the uniformity of drop formation and drop travel speed over a wide variation in drop ejection rates.
  • ink jet print heads of the type shown in FIG. 3 have been operated at drop ejection rates through and including 10,000 drops per second, and higher, and at drop ejection speeds in excess of 6 meters per second.
  • the drop speed nonuniformity has been observed at less than 15 percent over continuous and intermittent drop ejection conditions.
  • the drop position error is much less than one-third of a pixel at 11.81 drops per mm. (300 dots per in.) printing with an 8 kilohertz maximum printing rate.
  • the first pulse component, refill component 102 reaches a voltage amplitude and is maintained at this amplitude for a period of time prior to termination of the first or refill pulse component.
  • the second or ejection pulse component 104 reaches a negative voltage amplitude and is maintained at this amplitude for a period of time prior to termination of the second pulse.
  • these drive pulse components are trapezoidal in shape and have a different rise time to their respective voltage amplitudes from the fall time from their respective voltage amplitudes.
  • the two pulse components 102, 104 have rise times from about one microsecond to about 4 microseconds, maintain their respective voltage amplitudes from about 2 microseconds to about 7 microseconds, with the wait period 106 being greater than about 8 microseconds.
  • the rise time of the first pulse is about 2 microseconds
  • the first pulse achieves its voltage amplitude from about 3 microseconds to about 7 microseconds
  • the first pulse has a fall time from about 2 microseconds to about 4 microseconds
  • the wait period 106 is from about 15 microseconds to about 22 microseconds.
  • the ejection pulse component 104 is like the refill pulse component 102, except of opposite relative polarity.
  • time durations may be varied for different ink jet print head designs and different inks. Again, it is desirable for the ink meniscus to be traveling forward and to be at a common location at the occurrence of each pressure wave resulting from the application of the ejection pulse component 104. The parameters of the drive signal may be varied to achieve these conditions.
  • the dominant acoustic resonant frequency of the ink jet print head can be determined in a well-known manner.
  • the dominant resonant frequency of the ink jet print head typically corresponds to the resonant frequency of the ink meniscus.
  • the dominant acoustic resonant frequency in general corresponds to the standing wave resonant frequency through the liquid ink in the offset channel.
  • the complete drive signal is an entire set of pulses used in the formation of a single ink drop.
  • the complete signal includes the refill pulse component 102, the wait period 106, and the election pulse component 104.
  • a conventional spectrum analyzer may be used in determining the energy content of the drive signal at various frequencies. This energy content will vary with frequency from highs, or peaks, to valleys, or low points. A minimum energy content portion of the drive signal at certain frequencies is substantially less than the peak energy content at other frequencies. For example, a minimum energy content may be at least about 20 dB below the maximum energy content of the drive signal at other frequencies.
  • the drive signal may be adjusted to shift the frequency of this minimum energy content to be substantially equal to the dominant acoustic resonant frequency of the ink jet print head.
  • the drive signal adjusted in this manner, the energy of the drive signal at the dominant acoustic resonant frequency is minimized.
  • the effect of resonant frequencies of the ink jet print head on ink drop formation is minimized.
  • a preferred method of adjusting the drive signal to achieve high print quality and high printing rates comprises the step of adjusting the time duration of the first pulse, or refill pulse component 102, including rise time and fall time, and of the wait period 106. These pulse components are adjusted in duration until there is a minimum energy content of the drive signal at the frequency which is substantially equal to the dominant acoustic resonant frequency of the ink jet print head.
  • FIGS. 7 and 8 show a wave form and circuit for generating the wave form, respectively, that provides for such drop volume control.
  • 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, larger ink drops can be achieved.
  • the drive wave form By adjusting the drive wave form to reduce the volume of ink, smaller ink drops result.
  • FIG. 7 an advantageous drive signal for achieving grey scale printing is illustrated in FIG. 7.
  • This particular drive signal is a bipolar electric pulse 160 with a refill pulse component 162 and an ejection pulse component 164.
  • the components 162 and 164 are of voltages of opposite polarity.
  • the pulse components 162, 164 are also separated by a wait time period X.
  • the polarities of the components 162, 164 may be reversed from that shown in FIG. 7 depending upon the polarization of the piezoelectric driver mechanism 36 (FIGS. 1 and 3).
  • the ink chamber 22 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 103 toward the orifice outlet 14.
  • the ink chamber is rapidly constricted to cause the ejection of a drop of ink.
  • the duration of the refill pulse component is less than the time required for the meniscus, which has been withdrawn further into the orifice 103 as a result of the refill pulse, to return to an initial position adjacent to the orifice outlet 14.
  • the duration of the refill pulse component is less than one-half of the time period of the natural or resonance frequency of the meniscus.
  • this duration is less than about one-fifth of the time period of the meniscus' natural resonance frequency.
  • the resonance frequency of an ink meniscus in as orifice of an ink jet can be easily calculated from the properties of the ink and dimensions of the ink orifice in known manner.
  • the duration of the wait period increases, the ink meniscus moves closer to the orifice outlet 14 at the time the ejection pulse component 164 is applied. Smaller drop volumes of ejected drops are obtained by establishing a wait period which is short enough such that the eject pulse component is applied at a time that the meniscus is moving forward within the orifice and prior to the time that the meniscus reaches the orifice outlet.
  • the duration of the desired wait period and the eject pulse width 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.
  • the wait period and eject pulse component period are less than about one-half 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 configuration and the ink being used.
  • 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.
  • an ink jet print head of the type disclosed in the previously mentioned United States patent no. 5,087,930 is to be operated at a 4 kilohertz drop repetition rate.
  • various levels or volumes of ink in individual ink drops would result from altering the drive wave form of FIG. 7.
  • the spots or dots, if printed with hot melt ink on mylar print medium and before fusing, are expected to range in size from about 2.2 mils. to about 3.9 mils. If the ink is hot melt ink, following fusing of the ink spots on the print medium, by the application of pressure, this variation in spot size is even greater, for example, from about 2.6 mils to about 5.5 mils.
  • the wait period X would be set at 9 microseconds and the duration Y of the eject pulse component 64 would be set at 3 microseconds.
  • X would be set at 11 microseconds and Y would be set at 5 microseconds.
  • X would be set at 11 microseconds and Y would be set at 9 microseconds.
  • X would be set at 12 microseconds and Y would be set at 11 microseconds.
  • X would be set at 12 microseconds and Y would be set at 15 microseconds.
  • X would be set at 12 microseconds and Y would be set at 20 microseconds.
  • the amplitude and pulse width of the refill pulse component would be, for example, respectively forty volts and five microseconds.
  • the amplitude of the eject pulse component would be, for example, forty volts.
  • the ratio of the amplitude of the eject pulse component to the refill pulse component would increase as would the volume of ink included in the drops Similarly, as the pulse width of the eject pulse component increases, the ratio of the pulse width of the eject pulse component to the pulse width of the refill pulse component would also increase, as would the ink drop volume.
  • bipolar pulses of the type shown in FIG. 7 may be utilized to produce an individual ink drop.
  • the volume of ink in the ink drop is increased.
  • each bipolar pulse causes an additional amount of ink to be added to the ink drop and thus increases the volume of ink included in an ink drop before the ink drop separates from the orifice outlet.
  • 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.
  • a typical bipolar pulse of a string of such pulses may have a duration of from about 20 microseconds to 40 microseconds.
  • the typical time delay between individual bipolar pulses may range from about 30 to about 100 microseconds.
  • the time delay between individual pulses becomes greater than about 100 microseconds, the drops break off.
  • one exemplary separation between the bipolar pulses is about 40 microseconds. In this case the separation is about two times the duration of an individual bipolar pulse. If the time period between bipolar pulses is less than about 100 microseconds, or such other time at which drop break-off occurs, a successive bipolar pulse would add ink to the volume of an individual ink drop instead of generating a separate drop.
  • 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, assuming the case above where up to three bipolar pulses are 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 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 U.S. Patent 4,889,560. Again, however, the present invention is not limited to particular types of ink.
  • FIG. 8 illustrates an example of circuitry inside the signal source 37 that can be used to produce the bipolar electric pulse 160, which is applied to the piezoelectric ceramic material 36.
  • a central-processing unit (“CPU") 200 outputs a trigger pulse to refill a pulse timer 202 to initiate the pulse component 162.
  • the refill pulse timer 202 outputs a refill pulse drive signal at its output 206 to the negative input of a transducer driver 204, causing the transducer driver 204 to output the pulse component 162 of FIG. 7.
  • the duration of the component 162 is controlled by a count that is loaded from the CPU 200 through a counter preset line 208.
  • the signal at the output 206 goes to a zero value which (1) causes the negative input of the transducer driver 204 to return to a zero value and (2) initiates the wait period timer 210.
  • the pulse component 162 ends and the wait period begins.
  • the wait period has a duration X which is controlled by a count that is loaded from the CPU 200 through a counter preset line 212.
  • the signal at its output 214 goes to a zero value which initiates an eject pulse timer 218.
  • the output of the eject pulse timer 218 in a line 222 causes a positive input of the transducer driver 204 to go high and the pulse component 164 of FIG. 7 to begin.
  • the component 164 has a duration Y which is controlled by a count that is loaded from the CPU 200 through a counter preset line 216.
  • a unipolar drive pulse is illustrated.
  • the bipolar pulse drive signal of FIG.2 is preferred but some situations exist where a unipolar pulse is useable.
  • a unipolar drive pulse can be generated in a conventional manner by the signal generator 37 and applied to the acoustic drive mechanism 36.
  • the amplitude of the pulse shown in FIG. 9 may be increased from V0 to V1. This results in an increase in the volume of ink included in ink drop.
  • 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.
  • the volume of ink included in an ink drop is increased.
  • the pulse width of the illustrated pulse is reduced.
  • Combinations of amplitude and pulse width modulation approaches may also be used and different wave forms may be applied other than those shown in FIG. 9.
  • strings of pulses may be used with the number of pulses applied to the driver 30 between initial drop formation and break-off of the drop determining the volume of the ink drop.
  • control of the volume and travel of the ink drop from the print head orifice to the print medium can be assisted by providing a controllable electric field in the space therebetween.
  • This is not described herein but rather the disclosure of aforementioned copending application Serial No. 07/892,494, (EP 00 437 062) a continuation of applications Serial Nos. 07/698,172 and 07/451,080, is to be referenced.
  • This disclosure also appears in corresponding European patent application publication no. 437,062 dated July 17, 1991, which is incorporated herein by this reference.
  • an ink jet of the type having an ink chamber coupled to a source of ink, an ink drop ejecting orifice with an ink drop ejection orifice outlet, the ink drop ejecting orifice being coupled to the ink chamber, driver means for expanding and contracting the ink-chamber to eject a drop of ink from the ink drop ejecting orifice outlet, the method comprising: expanding the volume of the ink chamber to fill the chamber with ink from the source of ink and to draw the ink in the orifice toward the ink chamber and away from the ink drop ejection orifice outlet; waiting for a wait time period during which the ink chamber is returning back to is original volume so as to allow the ink the orifice to advance within the orifice away from the ink chamber and toward the ink drop ejection orifice outlet; and contracting the volume of the ink chamber following the wait period to eject a drop of ink.

Landscapes

  • Particle Formation And Scattering Control In Inkjet Printers (AREA)
EP19930304838 1992-06-19 1993-06-21 Méthode de commande d'un jet d'encre pour réaliser une haute qualité d'impression et un haut débit d'impression. Withdrawn EP0575204A3 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US90609192A 1992-06-19 1992-06-19
US906091 1992-06-19

Publications (2)

Publication Number Publication Date
EP0575204A2 true EP0575204A2 (fr) 1993-12-22
EP0575204A3 EP0575204A3 (fr) 1994-12-07

Family

ID=25421918

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19930304838 Withdrawn EP0575204A3 (fr) 1992-06-19 1993-06-21 Méthode de commande d'un jet d'encre pour réaliser une haute qualité d'impression et un haut débit d'impression.

Country Status (2)

Country Link
EP (1) EP0575204A3 (fr)
JP (1) JPH0640031A (fr)

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4403042A1 (de) * 1992-07-31 1995-08-03 Francotyp Postalia Gmbh Edge-Shooter-Tintenstrahldruckkopf und Verfahren zu seiner Herstellung
US5592203A (en) * 1992-07-31 1997-01-07 Francotyp-Postalia Gmbh Ink jet print head
EP0787589A2 (fr) * 1996-02-05 1997-08-06 Seiko Epson Corporation Tête d'enregistrement à jet d'encre
EP0816081A2 (fr) * 1996-07-05 1998-01-07 Seiko Epson Corporation Appareil d'enregistrement à jet d'encre et son procédé de commande
US5714078A (en) * 1992-07-31 1998-02-03 Francotyp Postalia Gmbh Edge-shooter ink jet print head and method for its manufacture
EP0845357A2 (fr) * 1996-10-30 1998-06-03 Mitsubishi Denki Kabushiki Kaisha Dispositif a ejection de liquide et imprimante l'utilisant
US6106092A (en) * 1998-07-02 2000-08-22 Kabushiki Kaisha Tec Driving method of an ink-jet head
US6161912A (en) * 1996-04-10 2000-12-19 Seiko Epson Corporation Method of maintaining and controlling the helmholtz resonant frequency in an ink jet print head
US6193343B1 (en) 1998-07-02 2001-02-27 Toshiba Tec Kabushiki Kaisha Driving method of an ink-jet head
EP1176014A1 (fr) * 2000-07-24 2002-01-30 Seiko Epson Corporation Dispositif d'enregistrement à jet d'encre et procédé de commande pour tête d'enregistrement à jet d'encre
US6957884B2 (en) * 2002-12-27 2005-10-25 Kinberly-Clark Worldwide, Inc. High-speed inkjet printing for vibrant and crockfast graphics on web materials or end-products
EP1695826A3 (fr) * 2005-02-24 2008-05-28 Toshiba TEC Kabushiki Kaisha Dispositif d'enregistrement à jet d'encre
EP2255968A1 (fr) * 2001-09-07 2010-12-01 Xaar Technology Limited Appareil de dépôt de gouttelettes
CN102145581A (zh) * 2009-12-10 2011-08-10 富士胶片株式会社 用于流体喷射器的驱动脉冲的分离
CN107443917A (zh) * 2016-05-30 2017-12-08 佳能株式会社 液体喷射设备和液体喷射头

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5659346A (en) * 1994-03-21 1997-08-19 Spectra, Inc. Simplified ink jet head
WO1996002392A1 (fr) * 1994-07-20 1996-02-01 Spectra, Inc. Systeme a jet d'encre goutte a la demande a haute frequence
US6328402B1 (en) 1997-01-13 2001-12-11 Minolta Co., Ltd. Ink jet recording apparatus that can reproduce half tone image without degrading picture quality
JP6737327B2 (ja) * 2016-02-24 2020-08-05 コニカミノルタ株式会社 インクジェット記録装置及びインクジェットヘッドの駆動方法
JP2020023058A (ja) * 2018-08-06 2020-02-13 ローランドディー．ジー．株式会社 液体吐出装置およびそれを備えたインクジェットプリンタ

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4491851A (en) * 1979-07-18 1985-01-01 Fujitsu Limited Method and circuit for driving an ink jet printer
US4523200A (en) * 1982-12-27 1985-06-11 Exxon Research & Engineering Co. Method for operating an ink jet apparatus
EP0194852A2 (fr) * 1985-03-11 1986-09-17 Dataproducts Corporation Système d'entraînement pour appareil à jet d'encre
US4734705A (en) * 1986-08-11 1988-03-29 Xerox Corporation Ink jet printer with satellite droplet control
JPS6371355A (ja) * 1986-09-12 1988-03-31 Fujitsu Ltd インクジエツトヘツドの駆動方法
JPS6394851A (ja) * 1986-10-09 1988-04-25 Canon Inc インクジエツト記録装置の駆動方法
EP0437062A2 (fr) * 1989-12-15 1991-07-17 Tektronix Inc. Méthode et appareil pour l'impression avec une tête d'impression à jet d'encre à la demande en utilisant un champ électrique
EP0467656A2 (fr) * 1990-07-16 1992-01-22 Tektronix, Inc. Méthode de commande pour tête d'impression à jet d'encre fonctionnant à la demande

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS59143653A (ja) * 1983-02-05 1984-08-17 Konishiroku Photo Ind Co Ltd 液体放出装置

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4491851A (en) * 1979-07-18 1985-01-01 Fujitsu Limited Method and circuit for driving an ink jet printer
US4523200A (en) * 1982-12-27 1985-06-11 Exxon Research & Engineering Co. Method for operating an ink jet apparatus
EP0194852A2 (fr) * 1985-03-11 1986-09-17 Dataproducts Corporation Système d'entraînement pour appareil à jet d'encre
US4734705A (en) * 1986-08-11 1988-03-29 Xerox Corporation Ink jet printer with satellite droplet control
JPS6371355A (ja) * 1986-09-12 1988-03-31 Fujitsu Ltd インクジエツトヘツドの駆動方法
JPS6394851A (ja) * 1986-10-09 1988-04-25 Canon Inc インクジエツト記録装置の駆動方法
EP0437062A2 (fr) * 1989-12-15 1991-07-17 Tektronix Inc. Méthode et appareil pour l'impression avec une tête d'impression à jet d'encre à la demande en utilisant un champ électrique
EP0467656A2 (fr) * 1990-07-16 1992-01-22 Tektronix, Inc. Méthode de commande pour tête d'impression à jet d'encre fonctionnant à la demande

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
IBM TECHNICAL DISCLOSURE BULLETIN., vol.24, no.2, July 1981, NEW YORK US pages 939 - 941 'Unimorph Drop Generator for an Ink Jet Printer' *
PATENT ABSTRACTS OF JAPAN vol. 12, no. 294 (M-730) 11 August 1988 & JP-A-63 071 355 (FUJITSU) 31 March 1988 *
PATENT ABSTRACTS OF JAPAN vol. 12, no. 332 (M-738) 8 September 1988 & JP-A-63 094 851 (CANON) *

Cited By (26)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5825382A (en) * 1992-07-31 1998-10-20 Francotyp-Postalia Ag & Co. Edge-shooter ink jet print head and method for its manufacture
US5592203A (en) * 1992-07-31 1997-01-07 Francotyp-Postalia Gmbh Ink jet print head
US5714078A (en) * 1992-07-31 1998-02-03 Francotyp Postalia Gmbh Edge-shooter ink jet print head and method for its manufacture
DE4403042A1 (de) * 1992-07-31 1995-08-03 Francotyp Postalia Gmbh Edge-Shooter-Tintenstrahldruckkopf und Verfahren zu seiner Herstellung
US5802687A (en) * 1992-07-31 1998-09-08 Francotyp-Postalia Ag & Co. Method of manufacturing an ink jet print head
EP0787589A2 (fr) * 1996-02-05 1997-08-06 Seiko Epson Corporation Tête d'enregistrement à jet d'encre
EP0787589A3 (fr) * 1996-02-05 1998-04-08 Seiko Epson Corporation Tête d'enregistrement à jet d'encre
US5933168A (en) * 1996-02-05 1999-08-03 Seiko Epson Corporation Recording method by ink jet recording apparatus and recording head adapted for said recording method
US6161912A (en) * 1996-04-10 2000-12-19 Seiko Epson Corporation Method of maintaining and controlling the helmholtz resonant frequency in an ink jet print head
EP0816081A2 (fr) * 1996-07-05 1998-01-07 Seiko Epson Corporation Appareil d'enregistrement à jet d'encre et son procédé de commande
EP0816081A3 (fr) * 1996-07-05 1998-09-16 Seiko Epson Corporation Appareil d'enregistrement à jet d'encre et son procédé de commande
EP0845357A3 (fr) * 1996-10-30 1999-09-15 Mitsubishi Denki Kabushiki Kaisha Dispositif a ejection de liquide et imprimante l'utilisant
EP0845357A2 (fr) * 1996-10-30 1998-06-03 Mitsubishi Denki Kabushiki Kaisha Dispositif a ejection de liquide et imprimante l'utilisant
US6155671A (en) * 1996-10-30 2000-12-05 Mitsubishi Denki Kabushiki Kaisha Liquid ejector which uses a high-order ultrasonic wave to eject ink droplets and printing apparatus using same
US6106092A (en) * 1998-07-02 2000-08-22 Kabushiki Kaisha Tec Driving method of an ink-jet head
US6193343B1 (en) 1998-07-02 2001-02-27 Toshiba Tec Kabushiki Kaisha Driving method of an ink-jet head
EP1176014A1 (fr) * 2000-07-24 2002-01-30 Seiko Epson Corporation Dispositif d'enregistrement à jet d'encre et procédé de commande pour tête d'enregistrement à jet d'encre
US6672700B2 (en) 2000-07-24 2004-01-06 Seiko Epson Corporation Ink jet recording apparatus and method for driving ink jet recording head incorporated in the apparatus
EP2255968A1 (fr) * 2001-09-07 2010-12-01 Xaar Technology Limited Appareil de dépôt de gouttelettes
US6957884B2 (en) * 2002-12-27 2005-10-25 Kinberly-Clark Worldwide, Inc. High-speed inkjet printing for vibrant and crockfast graphics on web materials or end-products
EP1695826A3 (fr) * 2005-02-24 2008-05-28 Toshiba TEC Kabushiki Kaisha Dispositif d'enregistrement à jet d'encre
CN102145581A (zh) * 2009-12-10 2011-08-10 富士胶片株式会社 用于流体喷射器的驱动脉冲的分离
CN107443917A (zh) * 2016-05-30 2017-12-08 佳能株式会社 液体喷射设备和液体喷射头
US10232632B2 (en) 2016-05-30 2019-03-19 Canon Kabushiki Kaisha Liquid ejection apparatus and liquid ejection head
US10336088B2 (en) 2016-05-30 2019-07-02 Canon Kabushiki Kaisha Liquid ejection apparatus and liquid ejection head
CN107443917B (zh) * 2016-05-30 2019-10-18 佳能株式会社 液体喷射设备和液体喷射头

Also Published As

Publication number Publication date
JPH0640031A (ja) 1994-02-15
EP0575204A3 (fr) 1994-12-07

Similar Documents

Publication Publication Date Title
EP0467656B1 (fr) Méthode de commande pour tête d'impression à jet d'encre fonctionnant à la demande
US5170177A (en) Method of operating an ink jet to achieve high print quality and high print rate
EP0575204A2 (fr) Méthode de commande d'un jet d'encre pour réaliser une haute qualité d'impression et un haut débit d'impression
US5124716A (en) Method and apparatus for printing with ink drops of varying sizes using a drop-on-demand ink jet print head
EP2106349B1 (fr) Éjection de gouttes ayant une taille de goutte variable d'une imprimante à jet d'encre
US6629741B1 (en) Ink jet recording head drive method and ink jet recording apparatus
EP1123806B1 (fr) Procede de commande d'une tete d'impression a jet d'encre
US6450603B1 (en) Driver for ink jet recording head
EP0437062A2 (fr) Méthode et appareil pour l'impression avec une tête d'impression à jet d'encre à la demande en utilisant un champ électrique
US6402282B1 (en) Operation of droplet deposition apparatus
US6494555B1 (en) Ink ejecting device
JPS62152860A (ja) 液体噴射記録ヘツド
US6419336B1 (en) Ink ejector
JPH0966603A (ja) インク噴射装置の駆動方法
EP1003643B1 (fr) Appareil a jet d'encre impulsionnel haute performance et procede correspondant
JP2002144570A (ja) 液滴吐出方法、画像形成方法、液体吐出装置およびヘッド
JP2785727B2 (ja) インクジェット式プリントヘッド及びその駆動方法
JP3500692B2 (ja) インクジェット記録装置
JPS63139749A (ja) インクジエツト記録ヘツド
JP2936358B2 (ja) インクジェット印刷ヘッドの駆動方法
JP3260351B2 (ja) インクジェットヘッド及びインクジェット式記録装置
JP2711008B2 (ja) インクジェット記録方法およびその装置
JP3892622B2 (ja) インクジェット記録ヘッドの駆動方法及び駆動装置
JP2663140B2 (ja) インクジェット記録方法
JP3302401B2 (ja) インクジェットの駆動装置及びインクジェットの駆動方法

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Kind code of ref document: A2

Designated state(s): DE FR GB IT

PUAL Search report despatched

Free format text: ORIGINAL CODE: 0009013

AK Designated contracting states

Kind code of ref document: A3

Designated state(s): DE FR GB IT

17P Request for examination filed

Effective date: 19950104

17Q First examination report despatched

Effective date: 19950425

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 19961221