EP0624468B1 - ContrÔle amélioré de la stimulation de jet d'encre - Google Patents

ContrÔle amélioré de la stimulation de jet d'encre Download PDF

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Publication number
EP0624468B1
EP0624468B1 EP19940303090 EP94303090A EP0624468B1 EP 0624468 B1 EP0624468 B1 EP 0624468B1 EP 19940303090 EP19940303090 EP 19940303090 EP 94303090 A EP94303090 A EP 94303090A EP 0624468 B1 EP0624468 B1 EP 0624468B1
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EP
European Patent Office
Prior art keywords
stimulation
feedback
drop generator
elements
ink jet
Prior art date
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Expired - Lifetime
Application number
EP19940303090
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German (de)
English (en)
Other versions
EP0624468A3 (fr
EP0624468A2 (fr
Inventor
James A. Katerberg
Mark C. Bowers
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.)
Kodak Versamark Inc
Original Assignee
Kodak Versamark Inc
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Publication date
Application filed by Kodak Versamark Inc filed Critical Kodak Versamark Inc
Publication of EP0624468A2 publication Critical patent/EP0624468A2/fr
Publication of EP0624468A3 publication Critical patent/EP0624468A3/fr
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Publication of EP0624468B1 publication Critical patent/EP0624468B1/fr
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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
    • B41J2/01—Ink jet
    • B41J2/015—Ink jet characterised by the jet generation process
    • B41J2/02—Ink jet characterised by the jet generation process generating a continuous ink jet
    • B41J2/025—Ink jet characterised by the jet generation process generating a continuous ink jet by vibration

Definitions

  • the present invention relates to ink jet printing systems and, more particularly, to an improved means for monitoring the stimulation in the drop generator of an ink jet printing system.
  • These stimulation control means function appropriately when the feedback signal has a sufficient signal-to-noise ratio.
  • the signal-to-noise ratio tends to be degraded in ink jet printers having long arrays and high resonant frequency.
  • Long arrays of jets have more charging electrodes which must be rapidly switched between ground potential and high voltage.
  • These switching transients produce electrical noise which can be picked up at the input to the stimulation control electronics.
  • Even with careful shielding and filtering, the electrical noise picked up by the stimulation control electronics can affect the stimulation drive amplitude and frequency. Higher frequency drop generators tend to have lower feedback signal amplitudes, further reducing the signal-to-noise ratio.
  • a fluid jet system for a printer is described in EP-A-0126536, wherein a pair of piezoelectric elements are mounted on a stimulator member of an ink jet orifice plate and provide an electrical feedback signal proportional in frequency and amplitude to acoustic waves traveling through the stimulator member.
  • This feedback signal may be used by a drive circuit to control the amplitude of a sinusoidal drive signal applied to the stimulator member.
  • One important object of the present invention is to provide an improved ink jet printing device having means for maintaining the desired stimulation conditions.
  • the invention provides an ink jet printing device as claimed in claim 1
  • the invention provides a method for monitoring stimulation in a drop generator of an ink jet printing system as claimed in claim 5.
  • Fig. 1 schematically illustrates a prior art monitoring and controlling means 11 for monitoring and controlling the vibration of a drop generator 10.
  • the monitoring and controlling means 11 comprises a piezoelectric element 12 bonded to the drop generator 10 for detecting the vibration amplitude of the drop generator 10.
  • Output 11, typically from the positive poled face, is provided to buffer amplifier 14.
  • the buffer amplifier 14 is typically located near the drop generator 10 to minimize signal attenuation in the cabling and to minimize noise pick-up.
  • the buffer amplifier 14 includes resistors 15a, 15b, and 15c, which are typically on the order of 100 K ⁇ , 56 K ⁇ , and 33 K ⁇ , respectively.
  • the buffer amplifier 14 output is provided to stimulation control electronics 20.
  • the stimulation control electronics 20 utilizes the amplified feedback signal as the controlling input for frequency and amplitude control of a stimulation driving signal.
  • the driving signal is applied to driving piezoelectric elements 18, causing the drop generator 10 to vibrate.
  • a means 21 for monitoring and controlling the stimulation of the drop generator 10, in accordance with the present invention, is illustrated, incorporating a differential buffer amplifier means 16.
  • the drop generator 10 is preferably a resonant body type drop generator, although it will be obvious to those skilled in the art that the concept of the present invention may be applied to other drop generators, such as piston type drop generators or traveling wave type drop generators.
  • stimulation control electronics 20 utilizes the feedback signal which is output from the differential buffer amplifier 16 as the controlling input for control of the stimulation frequency and amplitude.
  • the output of the stimulation control electronics 20 drives the piezoelectric elements 18 which cause the drop generator 10 to be stimulated.
  • the stimulation comprises a vibrational displacement of the resonant body type drop generator.
  • the present invention differs from the prior art in the manner in which the feedback signal is generated.
  • the present invention utilizes two feedback elements 12 and 22.
  • the two feedback elements 12 and 22 are typically piezoelectric elements, since piezoelectric elements produce a voltage between their electrodes in response to an applied strain.
  • the piezoelectric elements are marked by the vendor to indicate which electrode has the positive potential with respect to the other electrode in response to given stress.
  • piezoelectric element 12 is bonded to the drop generator 10 such that its negative electrode is grounded to the drop generator 10 and its positive electrode is used as a positive input 24 to the differential buffer amplifier 16.
  • Piezoelectric element 22 is bonded to the drop generator 10 with its positive electrode grounded to the drop generator 10 and its negative electrode being used as a negative input 26 to the differential buffer amplifier 16.
  • the difference between the signals from 12 and 22 is approximately twice the amplitude of the signal from piezoelectric element 12.
  • the electronic noise that is picked up will have similar sign and magnitude at the inputs 24 and 26 of the differential buffer amplifier 16.
  • the output from the differential buffer amplifier will therefore have most of the noise eliminated, as the noise signal at input 26 will be subtracted from the noise signal at input 24.
  • the use of two feedback crystals in a push-pull, or positive poled-negative poled configuration coupled with the differential buffer amplifier 16 increases the signal-to-noise ratio of the feedback signal, thereby reducing the effects of the electronic noise.
  • the inputs 24 and 26 each incorporate voltage follower amplifier 28 to provide high impedance to the feedback crystals 12 and 22.
  • a high impedance, on the order of 200 K ⁇ , shunt to ground is also incorporated into the inputs.
  • These high impedance shunts 30 provide a discharge path for any DC potential which may develop across the crystals.
  • the shunt can be any suitable shunt, including a simple resistor or a complex element where its impedance is less for DC than at the fundamental frequency of the output of the crystal.
  • the outputs of voltage follower amplifier 28 are input into plus and minus inputs of the differential amplifier 32.
  • the circuit 21 may include additional components, as needed, such as resistors 34, having values typically on the order of 10 K ⁇ ; resistors 36 and 38, each having values typically on the order of 20 K ⁇ ; and capacitor 40, used to prevent oscillations, and having a value typically on the order of 20 KF.
  • differential buffer amplifier 16 may be incorporated into the same electronics board as the stimulation control electronics, or may be located remote from the stimulation control electronics, without departing from the invention. In a preferred embodiment, the differential buffer amplifier 16 is located on an electronics board situated proximate to the drop generator 10. The outputs from the piezoelectric elements 12 and 22 are connected via a twisted pair of shielded cable to the differential buffer amplifier 16. A power amplifier (not shown) may be utilized at the output of the differential buffer amplifier 16 to drive a long cable to the stimulation control electronics 20.
  • the feedback elements 12 and 22 should be located proximate to each other so that noise picked up on their outputs will be similar. It may also be desirable to symmetrically place the feedback elements around a symmetry axis of the resonator to suppress detection of asymmetric resonant modes of the drop generator.
  • An asymmetric mode is one in which one side of the resonator is in expansion while the other side is in contraction. For such a mode, the feedback element in expansion would output a positive voltage. The symmetrically placed feedback element would undergo contraction. Because the second feedback element is oppositely poled, it would also output a positive voltage. The resulting output from the differential buffer amplifier 16 would therefore be near zero.
  • the present invention is useful in the field of ink jet printing, and has the advantage of improving stimulation monitoring in ink jet printing systems.
  • the present invention has the further advantage of improving signal monitoring by increasing the signal level and decreasing the noise of the system.
  • the present invention has the advantage of providing a means of reducing the sensitivity of stimulation control electronics to undesired resonances.

Claims (8)

  1. Dispositif d'impression par jet d'encre comportant un générateur de gouttes (10) pour produire des courants continus de gouttes d'encre à partir d'au moins un orifice et en outre, possédant un système électronique de commande de stimulation (20) pour maintenir les conditions de stimulation requises en réponse à une rétroaction à partir du générateur de gouttes, le dispositif comprenant des premier et deuxième éléments de rétroaction (12, 22) pour mesurer l'amplitude de stimulation dans le générateur de gouttes, caractérisé en ce que lesdites premier et deuxième éléments de rétroaction (12, 22) sont utilisés dans un montage symétrique et génèrent des signaux de sortie de rétroaction respectifs en réponse a l'amplitude de stimulation dans le générateur de gouttes (10), lesquels signaux présentent une grandeur sensiblement égale et des signaux mutuellement opposés, un moyen formant amplificateur (16) pour fournir un signal de sortie d'amplificateur au système électronique de commande de stimulation, et ledit moyen d'amplificateur comportant, comme entrées, lesdits signaux de sortie de rétroaction générés par les premier et deuxième éléments de rétroaction.
  2. Système d'impression par jet d'encre selon la revendication 1, selon lequel le signal de sortie de l'amplificateur est utilisé par le système électronique de commande de stimulation (20) pour la commande de la fréquence et de l'amplitude d'un signal d'entraînement de stimulation appliqué aux éléments d'entraînement (18) pour provoquer des déplacements de vibration d'un générateur de gouttes de type corps de résonance (10).
  3. Dispositif d'impression par jet d'encre selon la revendication 1, selon lequel le signal de sortie de l'amplificateur indique une différence entre les deux signaux de sortie de rétroaction.
  4. Système d'impression par jet d'encre selon la revendication 1, selon lequel le premier et le deuxième éléments (12, 22) sont placés de manière à supprimer le signal de sortie de l'amplificateur provenant de modes de stimulation de vibration indésirables.
  5. Procédé pour contrôler la stimulation dans un générateur de gouttes (10) d'un système d'impression par jet d'encre, le générateur de gouttes pour produire des courants continus de gouttes d'encre provenant d'au moins un orifice, le système d'impression par jet d'encre comportant des systèmes électroniques de commande de stimulation (20) pour maintenir les conditions de stimulation requises en réponse à une rétroaction provenant du générateur de gouttes et comprenant des premier et deuxième éléments de rétroaction (12, 22) et un moyen formant amplificateur (16) comportant une entrée constituée par les signaux de sortie de rétroaction générés par les premier et deuxième éléments de rétroaction, le procédé comprenant les étapes consistant à:
    a. mesurer l'amplitude de stimulation dans le générateur de gouttes (10) à l'aide des premier et deuxième éléments de rétroaction;
    b. générer des signaux de sortie de rétroaction provenant des premier et deuxième éléments de rétroaction en réponse à l'amplitude de stimulation dans le générateur de gouttes; et
    c. fournir un signal de sortie d'amplificateur au système électronique de commande de stimulation (20);
       caractérisé en ce que les signaux de sortie de rétroaction générés par les premier et deuxième éléments de rétroaction (12, 22) sont approximativement égaux en grandeur, et présentent des signes mutuellement opposés, lesdits signaux de sortie de rétroaction sont générés à l'aide des premier et deuxième éléments de rétroaction dans un montage symétrique, et ledit moyen formant amplificateur (16) comportant, comme entrées, lesdits signaux de rétroaction de sortie générés par lesdits premier et deuxième éléments de rétroaction.
  6. Procédé pour contrôler la stimulation selon la revendication 5, selon lequel le signal de sortie de l'amplificateur est utilisé par le système électronique de commande de stimulation (20) pour la commande de l'amplitude et de la fréquence d'un signal d'entraînement de la stimulation appliqué aux éléments d'entraînement (18) pour provoquer le déplacement des vibrations d'un générateur de gouttes de type à résonance (10).
  7. Procédé pour contrôler la stimulation selon la revendication 5 ou la revendication 6, selon lequel le signal de sortie de l'amplificateur indique une différence entre les deux signaux de sortie de rétroaction.
  8. Procédé pour contrôler la stimulation selon la revendication 5, 6 ou 7, selon lequel les premier et deuxième éléments de rétroaction (12, 22) sont positionnés de manière à supprimer le signal de sortie de l'amplificateur à partir des modes de stimulation de vibration indésirables.
EP19940303090 1993-05-12 1994-04-28 ContrÔle amélioré de la stimulation de jet d'encre Expired - Lifetime EP0624468B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US61184 1993-05-12
US6118493A 1993-05-13 1993-05-13

Publications (3)

Publication Number Publication Date
EP0624468A2 EP0624468A2 (fr) 1994-11-17
EP0624468A3 EP0624468A3 (fr) 1995-06-21
EP0624468B1 true EP0624468B1 (fr) 1997-11-12

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EP19940303090 Expired - Lifetime EP0624468B1 (fr) 1993-05-12 1994-04-28 ContrÔle amélioré de la stimulation de jet d'encre

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DE (1) DE69406712T2 (fr)

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5617266A (en) * 1979-07-20 1981-02-19 Ricoh Co Ltd Ink jet printer
US4417256A (en) * 1980-05-09 1983-11-22 International Business Machines Corporation Break-off uniformity maintenance
US4473830A (en) * 1983-01-13 1984-09-25 Eastman Kodak Company Ink jet print head
US4563688A (en) * 1983-05-16 1986-01-07 Eastman Kodak Company Fluid jet printer and method of ultrasonic cleaning
US4972201A (en) * 1989-12-18 1990-11-20 Eastman Kodak Company Drop charging method and system for continuous, ink jet printing

Also Published As

Publication number Publication date
DE69406712T2 (de) 1998-07-23
EP0624468A3 (fr) 1995-06-21
DE69406712D1 (de) 1997-12-18
EP0624468A2 (fr) 1994-11-17

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