EP0307160A2 - Moyens de microécoulement acoustique dans un appareil à jet d'encre - Google Patents

Moyens de microécoulement acoustique dans un appareil à jet d'encre Download PDF

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Publication number
EP0307160A2
EP0307160A2 EP88308220A EP88308220A EP0307160A2 EP 0307160 A2 EP0307160 A2 EP 0307160A2 EP 88308220 A EP88308220 A EP 88308220A EP 88308220 A EP88308220 A EP 88308220A EP 0307160 A2 EP0307160 A2 EP 0307160A2
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EP
European Patent Office
Prior art keywords
transducer
predetermined
ink
chamber
ink jet
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.)
Granted
Application number
EP88308220A
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German (de)
English (en)
Other versions
EP0307160A3 (en
EP0307160B1 (fr
Inventor
Stuart D. Howkins
John A. Mccormick
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.)
Ricoh Printing Systems America Inc
Original Assignee
Ricoh Printing Systems America Inc
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Filing date
Publication date
Application filed by Ricoh Printing Systems America Inc filed Critical Ricoh Printing Systems America Inc
Publication of EP0307160A2 publication Critical patent/EP0307160A2/fr
Publication of EP0307160A3 publication Critical patent/EP0307160A3/en
Application granted granted Critical
Publication of EP0307160B1 publication Critical patent/EP0307160B1/fr
Anticipated expiration legal-status Critical
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
    • B41J2/01—Ink jet
    • B41J2/135—Nozzles
    • B41J2/165—Preventing or detecting of nozzle clogging, e.g. cleaning, capping or moistening for nozzles
    • B41J2/16517—Cleaning of print head nozzles
    • B41J2/1652—Cleaning of print head nozzles by driving a fluid through the nozzles to the outside thereof, e.g. by applying pressure to the inside or vacuum at the outside of the print head
    • B41J2/16526—Cleaning of print head nozzles by driving a fluid through the nozzles to the outside thereof, e.g. by applying pressure to the inside or vacuum at the outside of the print head by applying pressure only

Definitions

  • This invention relates generally to ink jet apparatus, and more particularly to ink jet apparatus and methods of operating an ink jet apparatus in order to eliminate or at least substantially reduce problems associated with such apparatus during their start-up or utilization with pigmented inks.
  • pigmented inks Another common problem encountered with ink jet apparatus involves their use with pigmented inks. That is, during periods of non-use, the pigments contained within the ink of such ink jet apparatus have a propensity for settling out or agglomerating.
  • One approach used in the past to eliminate such settling was the incorporation of dyes in lieu of pigments within the ink.
  • pigments provide a much more intense color than their dye counterparts in typical inks used in an ink jet apparatus.
  • the particle displacement amplitude, a for a plane wave in a liquid of density, ⁇ , and sound velocity, c, having a pressure amplitude, p, and a frequency, f, would be:
  • c 1.5 x 105 cm/sec
  • f 50kHz
  • the particle displacement amplitude, a would be on the order of approximately 2000 angstroms. Solid particles in suspension within the liquid would, therefore, have an oscillatory motion of 2000 angstroms or less. In general, heavier denser particles would undergo an oscillatory motion having much smaller amplitudes.
  • Stable cavitation is generally associated with gas bubbles which already exist in the liquid, or which grow from dissolved gas coming out of solution under the action of the sound wave.
  • a gas bubble in such liquids has a very high mechanical Q factor, and hence at resonance, the amplitude of motion can rapidly build up to very high levels.
  • a variety of non-linear effects occur in the vicinity of the bubbles including bubble break-up and large pressure gradients in the liquid immediately surrounding the bubbles.
  • a phenomenon known as acoustic microstreaming also occurs in the vicinity of such an oscillating bubble and can, of itself, contribute to the ultrasonic dispersion and breaking up of agglomerates in a liquid.
  • Acoustic microstreaming is also a non-linear effect, but one which can occur at amplitudes well below the threshold for vaporous cavitation. Although generally associated with non-­linear liquid/air oscillations, there are also situations when bubbles are not present where vigorous microstreaming can occur. Acoustic microstreaming is a steady, non-oscillatory flow of the liquid on a very small scale, usually taking the form of microscopic eddies which can be pictured in a somewhat simplistic manner as the flow resulting from small scale radiation pressure gradients. Such radiation pressure gradients can be found around regions where a sharp discontinuity exists, such as at the tip of a vibrating rod having a radiating surface the dimension of which is very small as compared with its wavelength of vibration. Radiation pressure gradients may also be found around other types of geometrical discontinuities (e.g., corners or edges) of solid surfaces in contact with the liquid.
  • acoustic microstreaming results in a small scale stirring action in the liquid, the physical and chemical effects of which are well documented within the prior art.
  • the stirring action around the tip of a vibrating needle has been visualized by immersing the vibrating needle in a dilute solution of photographic developer just above a piece of partially exposed photographic paper, the image developed on such paper clearly showing microstreaming flow lines.
  • the action of microstreaming in stirring the inside of living cells has also been suggested as the mechanism which explains many of the biological effects of low amplitude ultrasonic radiation.
  • U. S. Patent No. 4,323,908 issued to Lee et al.
  • the Lee et al. device purges any entrapped air from the ink cavity and nozzle orifice of the print head of a drop-on-demand ink jet printer by energizing a tubular piezoelectric transducer with a series of pulses for a preselected short time period and at a repetition rate substantially equal to a resonant frequency of the ink capacity. Except during purging, the transducer operates asynchronously in drop-on-demand mode in response to discrete binary print signals.
  • the Lee et al. device While completely silent as to its applicability for acoustically mixing a pigmented ink, the Lee et al. device nevertheless utilizes a sinusoidal excitation of the drive transducer during non-printing periods for the purging of entrapped air from the ink cavity and nozzle orifices.
  • the Lee et al. device has an extremely narrow range of operation around the frequency of device resonance.
  • a stream of ink must be ejected from the nozzle orifices during purging of air therefrom, again since the device must operate at a resonance.
  • incorporation of such a device in an ink jet printer requires a complicated head tending system to ensure the removal of excess ink purged along with the air.
  • one or more crystal units are mounted on the ink reservoir and/or the writing grooves of a recording mechanism as described in Siemens-Zeitschrift , Volume 4, April 1977, pages 219-221.
  • Such grooves are concentrically enclosed by transducers which contain piezoceramic tubules the energy of which, according to German Specification No. 3,508,389, is lowered during the writing intervals such that it does not release any more droplets, but is adequate for the blending of the fluid.
  • German Specification No. 3,508,389 is lowered during the writing intervals such that it does not release any more droplets, but is adequate for the blending of the fluid.
  • German Specification avoids the problems associated with the device of U. S Patent No. 4,323,908 in that no head tending apparatus is required for the ink which is purged from the nozzle orifices.
  • Another object of the present invention is to provide a drop-on-demand ink jet apparatus and method of operating same which breaks up agglomerations of particles contained within the inks used in such apparatus by acoustic microstreaming.
  • Still another object of the present invention is to provide a method and apparatus for acoustic microstreaming in a drop-on-demand ink jet apparatus such that pigments contained in pigmented inks used in such apparatus are maintained in dispersion.
  • a further object of the present invention is to provide a method and apparatus for substantially reducing start-up problems, and for maintaining pigments in dispersion with drop-­on-demand ink jet apparatus, such that ink need not be ejected from the orifices of such apparatus thereby eliminating the necessity for complicated head tending equipment.
  • a still further object of the present invention is to provide a method and apparatus for acoustic microstreaming in a drop-on-demand ink jet apparatus which is adaptable for use both with conventional liquid, as well as hot melt or phase change, inks.
  • an ink jet apparatus having a scanning head employing at least one ink jet with a variable volume chamber which includes an ink droplet ejecting orifice, and a transducer, having a length mode resonant frequency, adapted to expand and contract along an axis of elongation in response to an electric field substantially transverse to the axis of elongation for ejection of droplets on demand from the ink droplet ejecting orifice.
  • acoustic microstreaming is induced within the apparatus by exciting the transducers associated with each variable volume chamber by a low voltage source with a predetermined waveform, preferably sinusoidal, having a predetermined range of frequencies centered about this length mode resonant frequency. While the lowest such voltage for excitation of the transducers to achieve acoustic microstreaming occurs, in accordance with the present invention, at the length mode resonant frequency, acoustic microstreaming is likewise achievable at greater or lesser frequencies by increasing the level of excitation voltage.
  • the excitation voltage is applied to the transducers for short periods of time during a carriage return cycle of the scanning print head, and during other such periods of printer inactivity to prevent problems associated with start-up and to maintain dispersion of pigments, or dissolution of dyes and other particles contained within the links used in such ink jet apparatus.
  • the geometry of the chamber must be carefully controlled to ensure that conditions are present which are conducive to acoustic microstreaming. Accordingly, the chamber length must be small as compared to the wavelength of the length mode disturbance of the transducers.
  • FIG. 1 an ink jet apparatus including an ink jet print heat 10 mounted for movement along a scanning path depicted by the arrows 12 and 14.
  • the ink jet print head 10 includes ink jet imaging systems supplying an array of ink jets having orifices 16, and an on-board or associated reservoir 18 supplied by a trough 20 located at the rear of the ink jet print head 10.
  • the ink jet print head 10 may be suitably formed in accordance with the teachings of U. S. Patent No. 4,459,601, issued July 10, 1984 to Stuart D. Howkins, assigned to the assignee of the present invention and incorporated herein by reference.
  • a chamber 22 having the orifice 16 ejects droplets of ink in response to the state of energization of a transducer 24 for each jet in the array.
  • the transducer 24 expands and contracts in directions indicated by the arrows shown in Fig. 3 along the axis of elongation and the movement is coupled into the chamber 22 by coupling means 26 which includes a foot 28, a viscoelastic material 30 juxtaposed to the transducer 24 and a diaphragm 32 which is preloaded to the position shown in Figs. 2 and 3 in accordance with the invention of U. S. Patent No. 4,418,355, issued November 29, 1983 to Thomas W. DeYoung et al., assigned to the assignee of the present invention and incorporated herein by reference.
  • the chamber 22 must, in accordance with an important aspect of the invention, be relatively small as compared to the wavelength of the length mode disturbance of the transducer 24. That is, the wavelength of the length mode disturbance is preferably approximately 20 times the chamber length as defined in U.S. Patent No. 4,459,601. Such a relationship ensures that the geometrical characteristics of the chamber 22 (i.e., corners, discontinuities, etc.) are small enough to be conducive to acoustic microstreaming.
  • a restricted opening 34 comprising an opening in a restrictor plate 36.
  • the cross-sectional area of the ink flowing into the chamber 22 through the inlet 34 is substantially constant during expansion and contraction of the transducer 24, notwithstanding the location of the inlet 34 immediately adjacent the coupling means 26 and the transducer 24.
  • the reservoir 18 which is formed in a chamber plate 40 includes a tapered edge 42 leading into the inlet 34 which is the invention of U. S Patent No. 4,424,521, issued January 3, 1981 to Arthur M. Lewis et al., assigned to the assignee of the present invention and incorporated herein by reference.
  • the reservoir 18 is compliant by virtue of the diaphragm 44 which is in communication with the ink through a large opening 46 in the restrictor plate 36 which is juxtaposed to an area of relief 48 in the plate 50 as shown in Fig. 2.
  • each jet in the array is isolated from the ink and communication with a single chamber 22.
  • each of the transducers 24 as shown in Fig. 2 is guided at the extremities thereof with intermediate portions of the transducer 24 being essentially unsupported as best shown in Fig. 2.
  • One extremity of the transducer 24 is guided by the cooperation of the foot 28 with a hole 52 in the plate 50. As shown in Fig. 2, the hole 52 in the plate 50 is slightly larger in diameter than the diameter of the foot 28.
  • the other extremity of the transducer 24 may be compliantly mounted in a block 54 by means of a compliant or elastic material 56 such as silicone rubber.
  • the compliant material 56 is located in slots 58 shown in Fig. 2 to provide support for the other extremity of the transducer 24.
  • Electrical contact with the transducer 24 is also made in a compliant manner by means of a compliant printed circuit 60, having conductive patterns 62 printed thereon, which is electrically coupled by suitable means such as solder 64 to the transducer 24.
  • the transducer 24 may be mounted to the block 54 by means of a silver conductive epoxy, thereby eliminating the need for the compliant material 56. Further details relating to the structure and operation of the above described ink jet apparatus may be found in the aforementioned U. S. Patent No. 4,459,601.
  • Figs. 4a - 4d there are shown several problems associated with start-up of typical ink jet apparatus such as the described immediately herein above.
  • a drop-on-­demand ink jet is first turned on after an idle period, there are a number of phenomena which cause the jet performance to exhibit differences from the steady running condition. These differences may range from a small change in droplet velocity to a complete failure to fire, and they may last for an indeterminate period of time if no steps are taken to intervene.
  • Such problems are generally manifested by poor print quality, or no print in extreme cases, when the printer is first turned on, and may require a substantial period of running or sometimes head tending to rectify same.
  • the underlying causes of such problems may be one or more of several different mechanisms, including for example evaporation of the ink causing a change in the ink's properties within the orifice.
  • these mechanisms fall into two categories: (1) a change in the properties of the ink in the orifice in the whole of the orifice region; and (2) a change in the properties of the ink in a region around the ink boundary within the orifice and/or the air.
  • the altered ink 100 will soon be purged from the orifice 16 and the problems will be fairly short lasting.
  • the second case as shown in Figs.
  • Each transducer 24 is excited, preferably sinusoidally, by a signal from a low voltage source 200 at frequencies within a predetermined range about the length mode resonant frequency of the transducers 24.
  • a signal may be generated by a simple oscillator or a conventional signal generator.
  • the length mode resonant frequency is approximately 55 kilohertz.
  • the source 200 is required to output the sinusoidal signal at a level of approximately one volt R. M. S.
  • the transducers 24 are so excited for a brief period of time (i.e., on the order of one second or less), preferably during periods of printer inactivity such as between carriage return cycles of the scanning print head 10 (Fig. 1).
  • the same effect can be achieved over a frequency range from about 10 kilohertz to about 100 kilohertz by increasing the excitation voltage somewhat.
  • an excitation voltage of less than approximately 100 volts, preferably 60-70 volts, and even more preferably 1-10 volts is required.
  • the level of excitation voltage in any case should be less than the drive voltage of the transducers 24. In this manner, excitation of the transducers 24 in order either to prevent start-up problems or to promote the dispersion of pigments within pigmented inks will not interfere with normal printer operations.
  • the foot 28 may comprise a generally cylindrical shape with a flat front surface proximate to the orifice 16 as shown in Figs. 2 and 3, or may be alternatively comprised of a substantially conical shape having the point of the cone situated proximate to the orifice 16 in order to concentrate the intensity changes associated with the low voltage sinusoidal signal applied to the transducers 24 as described herein above.
EP19880308220 1987-09-11 1988-09-06 Moyens de microécoulement acoustique dans un appareil à jet d'encre Expired - Lifetime EP0307160B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US9636387A 1987-09-11 1987-09-11
US96363 1987-09-11

Publications (3)

Publication Number Publication Date
EP0307160A2 true EP0307160A2 (fr) 1989-03-15
EP0307160A3 EP0307160A3 (en) 1990-01-10
EP0307160B1 EP0307160B1 (fr) 1993-04-28

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EP19880308220 Expired - Lifetime EP0307160B1 (fr) 1987-09-11 1988-09-06 Moyens de microécoulement acoustique dans un appareil à jet d'encre

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EP (1) EP0307160B1 (fr)
JP (1) JP2848613B2 (fr)
DE (1) DE3880598T2 (fr)
HK (1) HK94693A (fr)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0573238A2 (fr) * 1992-06-04 1993-12-08 Xerox Corporation Aspirateur pour imprimante acoustique à encre
EP0829361A2 (fr) * 1996-09-16 1998-03-18 Samsung Electronics Co., Ltd. Homogénéisation de l'encre dans un imprimante à jet d'encre
WO1999065685A2 (fr) * 1998-06-16 1999-12-23 Source Technologies, Inc. Procede et appareil pour systeme d'impression a jet d'encre
WO2000034046A1 (fr) * 1998-12-08 2000-06-15 Seiko Epson Corporation Tete d'impression a jet d'encre, imprimante a jet d'encre, et procede d'entrainement
US6491378B2 (en) 1998-12-08 2002-12-10 Seiko Epson Corporation Ink jet head, ink jet printer, and its driving method
US20160039207A1 (en) * 2010-10-18 2016-02-11 Xjet Ltd. Inkjet head storage and cleaning

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4323908A (en) * 1980-08-01 1982-04-06 International Business Machines Corp. Resonant purging of drop-on-demand ink jet print heads
US4418355A (en) * 1982-01-04 1983-11-29 Exxon Research And Engineering Co. Ink jet apparatus with preloaded diaphragm and method of making same
US4424521A (en) * 1982-01-04 1984-01-03 Exxon Research And Engineering Co. Ink jet apparatus and reservoir
US4439780A (en) * 1982-01-04 1984-03-27 Exxon Research And Engineering Co. Ink jet apparatus with improved transducer support
US4459601A (en) * 1981-01-30 1984-07-10 Exxon Research And Engineering Co. Ink jet method and apparatus
DE3508389A1 (de) * 1985-03-08 1986-09-11 Siemens AG, 1000 Berlin und 8000 München Vorrichtung zum durchmischen von tinten- und lacksuspensionen in schreibsystemen

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS57188372A (en) * 1981-01-30 1982-11-19 Exxon Research Engineering Co Ink jet device
JPS59164151A (ja) * 1983-03-09 1984-09-17 Nec Corp インクジエツトプリンタ用インク噴射ヘツドの駆動方法
JPS6135963A (ja) * 1984-07-30 1986-02-20 Canon Inc インクジエツト記録装置

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4323908A (en) * 1980-08-01 1982-04-06 International Business Machines Corp. Resonant purging of drop-on-demand ink jet print heads
US4459601A (en) * 1981-01-30 1984-07-10 Exxon Research And Engineering Co. Ink jet method and apparatus
US4418355A (en) * 1982-01-04 1983-11-29 Exxon Research And Engineering Co. Ink jet apparatus with preloaded diaphragm and method of making same
US4424521A (en) * 1982-01-04 1984-01-03 Exxon Research And Engineering Co. Ink jet apparatus and reservoir
US4439780A (en) * 1982-01-04 1984-03-27 Exxon Research And Engineering Co. Ink jet apparatus with improved transducer support
DE3508389A1 (de) * 1985-03-08 1986-09-11 Siemens AG, 1000 Berlin und 8000 München Vorrichtung zum durchmischen von tinten- und lacksuspensionen in schreibsystemen

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0573238A2 (fr) * 1992-06-04 1993-12-08 Xerox Corporation Aspirateur pour imprimante acoustique à encre
EP0573238A3 (fr) * 1992-06-04 1994-04-20 Xerox Corp
US6062682A (en) * 1996-09-16 2000-05-16 Samsung Electronics Co., Ltd. Method for homogenizing a pigment ink contained in an ink cartridge mounted in an ink jet printer
EP0829361A3 (fr) * 1996-09-16 1999-03-03 Samsung Electronics Co., Ltd. Homogénéisation de l'encre dans un imprimante à jet d'encre
EP0829361A2 (fr) * 1996-09-16 1998-03-18 Samsung Electronics Co., Ltd. Homogénéisation de l'encre dans un imprimante à jet d'encre
WO1999065685A2 (fr) * 1998-06-16 1999-12-23 Source Technologies, Inc. Procede et appareil pour systeme d'impression a jet d'encre
WO1999065685A3 (fr) * 1998-06-16 2000-04-06 Source Technologies Inc Procede et appareil pour systeme d'impression a jet d'encre
WO2000034046A1 (fr) * 1998-12-08 2000-06-15 Seiko Epson Corporation Tete d'impression a jet d'encre, imprimante a jet d'encre, et procede d'entrainement
US6474784B1 (en) 1998-12-08 2002-11-05 Seiko Epson Corporation Ink-jet head, ink jet printer, and its driving method
US6491378B2 (en) 1998-12-08 2002-12-10 Seiko Epson Corporation Ink jet head, ink jet printer, and its driving method
US20160039207A1 (en) * 2010-10-18 2016-02-11 Xjet Ltd. Inkjet head storage and cleaning
US10611155B2 (en) * 2010-10-18 2020-04-07 Xjet Ltd. Inkjet head storage and cleaning
US10864737B2 (en) 2010-10-18 2020-12-15 Xjet Ltd. Inkjet head storage and cleaning

Also Published As

Publication number Publication date
HK94693A (en) 1993-09-17
JP2848613B2 (ja) 1999-01-20
DE3880598T2 (de) 1993-12-23
JPH01157861A (ja) 1989-06-21
DE3880598D1 (de) 1993-06-03
EP0307160A3 (en) 1990-01-10
EP0307160B1 (fr) 1993-04-28

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