CA1244714A - Method for selective multi-cycle resonant operation of an ink jet apparatus for controlling dot size - Google Patents
Method for selective multi-cycle resonant operation of an ink jet apparatus for controlling dot sizeInfo
- Publication number
- CA1244714A CA1244714A CA000476889A CA476889A CA1244714A CA 1244714 A CA1244714 A CA 1244714A CA 000476889 A CA000476889 A CA 000476889A CA 476889 A CA476889 A CA 476889A CA 1244714 A CA1244714 A CA 1244714A
- Authority
- CA
- Canada
- Prior art keywords
- ink
- ink jet
- electrical signal
- period
- jet apparatus
- 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.)
- Expired
Links
- 238000000034 method Methods 0.000 title claims description 42
- 230000001965 increasing effect Effects 0.000 claims description 4
- 239000012530 fluid Substances 0.000 claims description 3
- 238000007493 shaping process Methods 0.000 claims 2
- 238000007639 printing Methods 0.000 abstract description 13
- 238000007641 inkjet printing Methods 0.000 abstract description 2
- 230000001276 controlling effect Effects 0.000 abstract 1
- 239000000976 ink Substances 0.000 description 128
- 238000013461 design Methods 0.000 description 4
- 230000009467 reduction Effects 0.000 description 4
- 230000001419 dependent effect Effects 0.000 description 3
- 230000000670 limiting effect Effects 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- 230000008602 contraction Effects 0.000 description 2
- 230000010355 oscillation Effects 0.000 description 2
- 241000272470 Circus Species 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 239000000356 contaminant Substances 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000011038 discontinuous diafiltration by volume reduction Methods 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000013013 elastic material Substances 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 238000003384 imaging method Methods 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 238000009533 lab test Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 230000010287 polarization Effects 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 230000002829 reductive effect Effects 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 229910000679 solder Inorganic materials 0.000 description 1
- 230000036962 time dependent Effects 0.000 description 1
- 239000003190 viscoelastic substance Substances 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
- B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
- B41J2/01—Ink jet
- B41J2/015—Ink jet characterised by the jet generation process
- B41J2/04—Ink jet characterised by the jet generation process generating single droplets or particles on demand
- B41J2/045—Ink jet characterised by the jet generation process generating single droplets or particles on demand by pressure, e.g. electromechanical transducers
- B41J2/04501—Control methods or devices therefor, e.g. driver circuits, control circuits
- B41J2/04595—Dot-size modulation by changing the number of drops per dot
-
- 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
- B41J2/21—Ink jet for multi-colour printing
- B41J2/2121—Ink jet for multi-colour printing characterised by dot size, e.g. combinations of printed dots of different diameter
- B41J2/2128—Ink jet for multi-colour printing characterised by dot size, e.g. combinations of printed dots of different diameter by means of energy modulation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- B41J2202/00—Embodiments of or processes related to ink-jet or thermal heads
- B41J2202/01—Embodiments of or processes related to ink-jet heads
- B41J2202/06—Heads merging droplets coming from the same nozzle
Abstract
ABSTRACT OF THE DISCLOSURE
The volume of ink ejected from an ink jet printing apparatus during one cycle of operation for printing a dot upon a recording medium is controlled within that cycle of operation by operating the ink jet apparatus via the application of a pulse train having a periodicity equivalent to the dominant reson-ant frequency of the ink jet apparatus, whereby each pulse of the pulse train causes an ink droplet of sub-stantially predictable volume to be ejected, a given number of successive pulses during each printing cycle is applied to the ink jet apparatus for causing an equal number of ink droplets to be ejected for control-ling the boldness of the dot being printed.
The volume of ink ejected from an ink jet printing apparatus during one cycle of operation for printing a dot upon a recording medium is controlled within that cycle of operation by operating the ink jet apparatus via the application of a pulse train having a periodicity equivalent to the dominant reson-ant frequency of the ink jet apparatus, whereby each pulse of the pulse train causes an ink droplet of sub-stantially predictable volume to be ejected, a given number of successive pulses during each printing cycle is applied to the ink jet apparatus for causing an equal number of ink droplets to be ejected for control-ling the boldness of the dot being printed.
Description
J
1 The field of the present invention relates
1 The field of the present invention relates
2 generally to ink jet apparatus, and more specifically
3 to a method for operating an ink jet apparatus in a
4 resonant mode for providing high resolution printing.
The design of practical ink jet devices and 6 apparatus for producing a single droplet of ink on 7 demand is relatively new in the art. In prior drop-on-8 demand ink jet apparatus, the volume oE each indiv-9 idual ink droplet is typically dependent upon the geom-etry of the ink jet apparatus, the type of ink used, 11 and the magnitude of a positive pressure developed 12 within the ink chamber of the ink jet for ejecting an 13 ink droplet from an associated orifice. The effective 14 diameter and design of the orifice, the volume and configuration of the ink chamber associated with the 16 orifice, the transducer design, and the method of coup-17 ling the transducer to the ink chamber, are other fac-18 torg determining the volume of individual ink droplets 19 ejected from the orifice. In any such ink jet appara-tus high resolution imaging requires that relatively 21 small or low volume ink droplets be ejected from the 22 apparatus. Typically, such smaller sized ink droplets 23 are obtained by decreasing the diameter of the orifices 24 of the ink jet device. However, it is difficult to fabricate small diameter jet orifices, and the opera-26 tion oE an ink jet device incorporating such small 27 diameter orifices is typically plagued with orifice 28 clogging problems (by dried ink, contaminants in the 29 ink, paper dust, etc.), adverse effects of a high ratio of surface tension forces to inertial forces, poor aim, 31 and so forth.
~7,, ~.~
- 12~L~7~
Many attempts have been made to control the 2 printing density and resolution of printing with an ink 3 jet printer. In U.S. Patent No. 3,977,007, issued on 4 August 24, 1976, to J. A. Burry et al, shades of gray are reproduced in an ink jet printer by selectively 6 adjusting by one the number of drops of ink deposited 7 at a predetermined dot location in a dot matrix. In 8 U.S. Patent No. 4,018,383, issued on April 19, 1977 to 9 A. D. Paton et al, a ~ethod is taught for eliminating satellite droplets in continuous ink jet system, where 11 upon printing the method further provides for select-12 ively eliminating or including the satellite droplets 13 to control the density of the droplet streams. In a 14 continuous ink jet apparatus disclosed in U.S. Patent No. 4,047,183, issued to H. H. Taub, on September 6, 16 1977, a laser is used to sense the frequency components 17 of a continuous ink jet stream for controlling charac-18 teristics of a perturbation drive signal operating the 19 apparatus, for providing the control over the formation and shape of the ink droplets comprising the ink drop-21 let stream.
In U.S. Patent No. 4,281,333, issued to M.
2 Tsu2uki et al, on July 28 1981, the volume or size of 3 ink droplets ejected from a drop-on-demand ink jet 4 apparatus are controlled merely by varying the ampli-tude or power envelope of the drive signal waveform 6 used to operate the ink jet apparatus. In U.S. Patent 7 4,337,~L70, issued to T. Furukawa, on June 29, 1982, the 8 dot size produced by an ink jet printer is controlled 9 by varying the frequency of oscillation of a vibrator for vibrating ink in the ink head, for causing droplets 11 of ink to be ejected, which droplets are electrostat-12 ically deflected onto or away from a receiving medium 13 for controlling the density of printing. [~.S. Patent 14 ~o. 4,393,384, granted to E. L. Kyser on July 12, 1983, 7~4 -teaches a method for operating a drop-on-demand ink jet apparatus for controlling the volume and velocity of the ink droplets produced for ultimately controlling the quality of printing, whereby the control is ob-tained by controlably and successively first reducing the volume of the associated ink chamber, then increas-ing the volume, then immediately reducing the volume to an amount less than the first volume reduction, fol-lowed by an increase in the volume of the ink chamber for ejecting the ink droplet. In U.S. Patent No.
4,493,388, issued to Y. Matsuda et al, on July 12, 1983, a method of operating an ink jet device is disclosed, in which the pattern of the electrical signal applied to the transducer includes an interruption period longer than a predetermined time period followed by the time periods of three successive electrical signals, at least one of the amplitude and width of the second one of the three electrical signals being enlarged relative to the other two, for preventing a reduction in the radius of the second ink droplet ejected after the interruption period. No disclosure is made in any of the preceding briefly described patents for operat-ing an ink jet apparatus to excite certain resonances thereof, for providing control over the size and volume of the ejected ink droplets.
The present invention provides a method for operating an ink jet apparatus for controlling the dot size of ink printed upon a recording medium, the ink jet apparatus including transducer means operable for producing a positive pressure disturbance within an associated ink chamber filled with ink, for ejecting an ink droplet from an associated orifice. The method according to the invention comprises the steps of:
(1) operating the transducer means for synchronously exciting either one or a combination of C
.. . . . . .. .
- 4 - 1~4~1~
fluid or mechanical resonant frequencies of the ink jet apparatus for producing a dominant resonant frequency within the ink chamber and associated ink;
and (2) permitting either one of one-cycle, or one subharmonic cycle of the dominant resonant frequency to be produced, for substantially predictably controlling the volume of an ink droplet ejected from the orifice via the resultant pressure disturbance produced in the chamber.
According to a preferred embodimen-t, the above steps (1) and (2) are successively repeated a desired number of times, in synchronism with the dominant resonant frequencyt for producing a plurality of ink droplets within a time period permitting the droplets to merge while airborne or upon the recording medium, for controlably increasing the resultant dot size upon the recording medium relative to the dot size obtained from a single droplet of ink.
In the drawing, wherein like items have common reference designations:
Figure 1 is a sectional view of an illustrated .ink jet apparatus;
Fi~ure 2 is an enlarged view of a portion of section of Fig. 1;
Figure 3 is an exploded projectional or pictorial view of the ink jet apparatus, including the embodiments shown in Figs. 1 and 2;
,'.;
~ t ~Z~714 - 4a -Figure 4 shows the waveshape for electrical pulses of a preferred embodiment;
Figure S shows a sinusoidal waveshape for electrical drive signals of another embodiment of the invention;
Figure 6 shows a half-wave sinusoidal wave-form for a third embodiment of the invention;
-` ~L2~
The design of practical ink jet devices and 6 apparatus for producing a single droplet of ink on 7 demand is relatively new in the art. In prior drop-on-8 demand ink jet apparatus, the volume oE each indiv-9 idual ink droplet is typically dependent upon the geom-etry of the ink jet apparatus, the type of ink used, 11 and the magnitude of a positive pressure developed 12 within the ink chamber of the ink jet for ejecting an 13 ink droplet from an associated orifice. The effective 14 diameter and design of the orifice, the volume and configuration of the ink chamber associated with the 16 orifice, the transducer design, and the method of coup-17 ling the transducer to the ink chamber, are other fac-18 torg determining the volume of individual ink droplets 19 ejected from the orifice. In any such ink jet appara-tus high resolution imaging requires that relatively 21 small or low volume ink droplets be ejected from the 22 apparatus. Typically, such smaller sized ink droplets 23 are obtained by decreasing the diameter of the orifices 24 of the ink jet device. However, it is difficult to fabricate small diameter jet orifices, and the opera-26 tion oE an ink jet device incorporating such small 27 diameter orifices is typically plagued with orifice 28 clogging problems (by dried ink, contaminants in the 29 ink, paper dust, etc.), adverse effects of a high ratio of surface tension forces to inertial forces, poor aim, 31 and so forth.
~7,, ~.~
- 12~L~7~
Many attempts have been made to control the 2 printing density and resolution of printing with an ink 3 jet printer. In U.S. Patent No. 3,977,007, issued on 4 August 24, 1976, to J. A. Burry et al, shades of gray are reproduced in an ink jet printer by selectively 6 adjusting by one the number of drops of ink deposited 7 at a predetermined dot location in a dot matrix. In 8 U.S. Patent No. 4,018,383, issued on April 19, 1977 to 9 A. D. Paton et al, a ~ethod is taught for eliminating satellite droplets in continuous ink jet system, where 11 upon printing the method further provides for select-12 ively eliminating or including the satellite droplets 13 to control the density of the droplet streams. In a 14 continuous ink jet apparatus disclosed in U.S. Patent No. 4,047,183, issued to H. H. Taub, on September 6, 16 1977, a laser is used to sense the frequency components 17 of a continuous ink jet stream for controlling charac-18 teristics of a perturbation drive signal operating the 19 apparatus, for providing the control over the formation and shape of the ink droplets comprising the ink drop-21 let stream.
In U.S. Patent No. 4,281,333, issued to M.
2 Tsu2uki et al, on July 28 1981, the volume or size of 3 ink droplets ejected from a drop-on-demand ink jet 4 apparatus are controlled merely by varying the ampli-tude or power envelope of the drive signal waveform 6 used to operate the ink jet apparatus. In U.S. Patent 7 4,337,~L70, issued to T. Furukawa, on June 29, 1982, the 8 dot size produced by an ink jet printer is controlled 9 by varying the frequency of oscillation of a vibrator for vibrating ink in the ink head, for causing droplets 11 of ink to be ejected, which droplets are electrostat-12 ically deflected onto or away from a receiving medium 13 for controlling the density of printing. [~.S. Patent 14 ~o. 4,393,384, granted to E. L. Kyser on July 12, 1983, 7~4 -teaches a method for operating a drop-on-demand ink jet apparatus for controlling the volume and velocity of the ink droplets produced for ultimately controlling the quality of printing, whereby the control is ob-tained by controlably and successively first reducing the volume of the associated ink chamber, then increas-ing the volume, then immediately reducing the volume to an amount less than the first volume reduction, fol-lowed by an increase in the volume of the ink chamber for ejecting the ink droplet. In U.S. Patent No.
4,493,388, issued to Y. Matsuda et al, on July 12, 1983, a method of operating an ink jet device is disclosed, in which the pattern of the electrical signal applied to the transducer includes an interruption period longer than a predetermined time period followed by the time periods of three successive electrical signals, at least one of the amplitude and width of the second one of the three electrical signals being enlarged relative to the other two, for preventing a reduction in the radius of the second ink droplet ejected after the interruption period. No disclosure is made in any of the preceding briefly described patents for operat-ing an ink jet apparatus to excite certain resonances thereof, for providing control over the size and volume of the ejected ink droplets.
The present invention provides a method for operating an ink jet apparatus for controlling the dot size of ink printed upon a recording medium, the ink jet apparatus including transducer means operable for producing a positive pressure disturbance within an associated ink chamber filled with ink, for ejecting an ink droplet from an associated orifice. The method according to the invention comprises the steps of:
(1) operating the transducer means for synchronously exciting either one or a combination of C
.. . . . . .. .
- 4 - 1~4~1~
fluid or mechanical resonant frequencies of the ink jet apparatus for producing a dominant resonant frequency within the ink chamber and associated ink;
and (2) permitting either one of one-cycle, or one subharmonic cycle of the dominant resonant frequency to be produced, for substantially predictably controlling the volume of an ink droplet ejected from the orifice via the resultant pressure disturbance produced in the chamber.
According to a preferred embodimen-t, the above steps (1) and (2) are successively repeated a desired number of times, in synchronism with the dominant resonant frequencyt for producing a plurality of ink droplets within a time period permitting the droplets to merge while airborne or upon the recording medium, for controlably increasing the resultant dot size upon the recording medium relative to the dot size obtained from a single droplet of ink.
In the drawing, wherein like items have common reference designations:
Figure 1 is a sectional view of an illustrated .ink jet apparatus;
Fi~ure 2 is an enlarged view of a portion of section of Fig. 1;
Figure 3 is an exploded projectional or pictorial view of the ink jet apparatus, including the embodiments shown in Figs. 1 and 2;
,'.;
~ t ~Z~714 - 4a -Figure 4 shows the waveshape for electrical pulses of a preferred embodiment;
Figure S shows a sinusoidal waveshape for electrical drive signals of another embodiment of the invention;
Figure 6 shows a half-wave sinusoidal wave-form for a third embodiment of the invention;
-` ~L2~
-5-1 Figure 7 shows a quarter-wave sinusoidal 2 waveform for elect~ical pulses of a fourth embodiment 3 of the inven~ion;
4 Figure 8 shows a sawtooth waveform for a ; S fith embodiment of the invention;
4 Figure 8 shows a sawtooth waveform for a ; S fith embodiment of the invention;
6 Figure 9 shows a triangular waveform for
7 electrical pulses of a sixth embodiment of the inven
8 tion;
9 Figure 10 shows printouts (~) through (F)
10 obtained from the illustrative ink jet device using the
11 method of the present invention; and : 12 ~igure 11 font printouts (~) through (C), 13 respectively, illustrates typical printout density 14 control obtainable from operating the illustrative in~
15 jet device using the method of the present invention.
. 16 Figure 12 shows droplets in flight produced ~ 17 using the present method.
18 In Figures 1-3, an ink jet apparatus of 19 U.S. Patent No. 4,459,601 granted July 10, 1984, 20 for "Improved Ink ~et Method and Appar-21 atus" is shown (the invention thereof is assigned to 22 the assignee of the present invention). The 2reSenL
23 invention was discovered during developmen~ of improved 24 methods for operating the previously mentioned ink jet apparaLus for o~taining high resolution printing.
26 i~owever, -~he presen~ inventors ~elieve that the various 27 em~odiments of their inven-tion illustrated and claimed 28 herein are applica`Dle for use with a broad range of ~9 i.nk jet apparaLus (especially drop-on-demande ink jet apparatus).
.
~?
1 Accordingly, the ink jet apparatus discussed herein is 2 presented Eor purposes of illustration oE the method of 3 the present invention, and is not meant to be limiting.
4 Also, only the basic mechanical features and operation 5 of this apparatus are discussed in the following 6 paragraphs.
7 With reference to Figures 1-3, the illus-8 trative ink jet apparatus includes a chamber 200 having 9 an orifice 202 ~or ejecting droplets of ink in response to the state of energization oE a transducer 204 for 11 each jet in an array of such jets (see Fig. 3). The
15 jet device using the method of the present invention.
. 16 Figure 12 shows droplets in flight produced ~ 17 using the present method.
18 In Figures 1-3, an ink jet apparatus of 19 U.S. Patent No. 4,459,601 granted July 10, 1984, 20 for "Improved Ink ~et Method and Appar-21 atus" is shown (the invention thereof is assigned to 22 the assignee of the present invention). The 2reSenL
23 invention was discovered during developmen~ of improved 24 methods for operating the previously mentioned ink jet apparaLus for o~taining high resolution printing.
26 i~owever, -~he presen~ inventors ~elieve that the various 27 em~odiments of their inven-tion illustrated and claimed 28 herein are applica`Dle for use with a broad range of ~9 i.nk jet apparaLus (especially drop-on-demande ink jet apparatus).
.
~?
1 Accordingly, the ink jet apparatus discussed herein is 2 presented Eor purposes of illustration oE the method of 3 the present invention, and is not meant to be limiting.
4 Also, only the basic mechanical features and operation 5 of this apparatus are discussed in the following 6 paragraphs.
7 With reference to Figures 1-3, the illus-8 trative ink jet apparatus includes a chamber 200 having 9 an orifice 202 ~or ejecting droplets of ink in response to the state of energization oE a transducer 204 for 11 each jet in an array of such jets (see Fig. 3). The
12 transducer 204 expands and contracts (in directions
13 indicated by the arrows in Fig. 2) along its axis of
14 elongation, and the movement is coupled to the chamber 200 by coupling means 206 which includes a Eoot 207, a 16 visco-elastic material 208 juxtaposed to the foot 207, 17 and a diaphragm 210 which is reloaded to the position 18 shown in Figures 1 and 2.
19 Ink flows into the chamber 200 from an unpressurized reservoir 212 through restricted inlet 21 means provided by a restricted opening 214. The inlet 22 214 comprises an opening in a restrictor plate (see 23 Fig. 3). As shown in ~igure 2, the reservoir 212 which 24 is formed in a chamber plate 220 includes a tapered edge 222 leading into the inlet 214. ~s shown in Fig.
26 3, the reservoir 212 is supplied with a feed tube 223 27 and a vent tube 225. The reservoir 212 is compliant by 28 virtue of the diaphragm 210, which is in communication 29 with the ink through a large opening 227 in the res-trictor plate 216 which is juxtaposed to an area of 31 relief 229 in the plate 226.
1 One èxtremity of each one of the transducers 2 204 is guided by the cooperation of a foot 207 with a 3 hole 224 in a plate 226. As shown, the feet 207 are 4 slideably retained within the holes 224. The other 5 extremities of each one of the transducers 204 are 6 compliantly mounted in a block 228 by means of a com-7 pliant or elastic material 230 located in slots 232 8 (see Fig. 3) so as to provide support for the other 9 extremities of the transducers 204. Electrical contact 10 with the transducers 204 is also made in a compliant 11 manner by means of a compliant printed circuit 234, 12 which is electrically coupled by suitable means such as 13 solder 236 to an electrode 260 of the transducers 204.
14 Conductive patterns 238 are provided on the printed
19 Ink flows into the chamber 200 from an unpressurized reservoir 212 through restricted inlet 21 means provided by a restricted opening 214. The inlet 22 214 comprises an opening in a restrictor plate (see 23 Fig. 3). As shown in ~igure 2, the reservoir 212 which 24 is formed in a chamber plate 220 includes a tapered edge 222 leading into the inlet 214. ~s shown in Fig.
26 3, the reservoir 212 is supplied with a feed tube 223 27 and a vent tube 225. The reservoir 212 is compliant by 28 virtue of the diaphragm 210, which is in communication 29 with the ink through a large opening 227 in the res-trictor plate 216 which is juxtaposed to an area of 31 relief 229 in the plate 226.
1 One èxtremity of each one of the transducers 2 204 is guided by the cooperation of a foot 207 with a 3 hole 224 in a plate 226. As shown, the feet 207 are 4 slideably retained within the holes 224. The other 5 extremities of each one of the transducers 204 are 6 compliantly mounted in a block 228 by means of a com-7 pliant or elastic material 230 located in slots 232 8 (see Fig. 3) so as to provide support for the other 9 extremities of the transducers 204. Electrical contact 10 with the transducers 204 is also made in a compliant 11 manner by means of a compliant printed circuit 234, 12 which is electrically coupled by suitable means such as 13 solder 236 to an electrode 260 of the transducers 204.
14 Conductive patterns 238 are provided on the printed
15 circu;t 234.
16 The plate 226 (see Figures 1 and 3) includes
17 holes 224 at the base of a slot 237 which receive the
18 feet 207 of the transducers 204, as previously men-
19 tioned. The plate 226 also includes receptacle 239
20 for a heater sandwich 240, the latter including a
21 heater element 242 with coils 244, a hold down plate
22 246, a spring 248 associated with the plate 246, and a
23 support plate 2S0 located immediately beneath the
24 heater 240. The slot 253 is for receiving a thermistor
25 252, the latter being used to provide monitoring of the
26 temperature of the heater element 242. The entire
27 heater 240 is maintained within the receptacle in the
28 plate 226 by a cover plate 254.
29 As shown in Fig. 3, the variously described
30 components of the ink jet apparatus are held together
31 by means of screws 256 which extend upwardly through
32 openings 257, and screws 258 which extend downwardly
33 through openings 259, the latter to hold a printed
34 circuit board 234 in plate on the plate 228. The 12~ L4 1 dashed lines in Fig. 1 depict connections 263 to the 2 printed circuits 238 on the printed circuit board 234.
3 The connections 263 connect a controller 261 to the ink 4 jet apparatus, for controlling the operation of the 5 latter.
6 In conventional operation of the ink jet 7 apparatus, the controller 261 is programmed to at an 8 appropriate time, via its connection to the printed 9 circuits 238, apply a voltage to a selected one or ones 10 of the hot electrodes 260 of the transducers 20~. The 11 applied voltage causes an electric field to be produced 12 transverse to the axis of elongation of the selected 13 transducers 204, causing the transducers 204 to con-14 tract along their elongated axis. When a particular 15 transducer 204 so contracts upon energization, the 16 portion of the diaphragm 210 located below the foot 207 17 of the transducer 204 moves in the direction of the 18 contracting transducer 204, thereby effectively expand-19 ing the volume of the associated chamber 200. As the 20 volume of the particular chamber 200 is so expanded, a 21 negative pressure is initially created within the cham-22 ber, causing ink therein to tend to move away from the 23 associated orifice 202, while simultaneously permit-24 ting ink from the reservoir 212 to flow through the 25 associated restricted opening or inlet 214 into the 26 chamber 200. The amount of ink that flows into the 27 chamber 200 during the refill is greater than the 28 amount that flows back out through the restrictor 214 29 during firing. The time between refill and fire is not 30 varied during operation of the jet thus providing a 31 "fill before fire" cycle. Shortly thereafter, the 32 controller 261 is programmed to remove the voltage or 33 drive signal from the particular one or ones of the 34 selected transducers 204, causing the transducer 204 or
3 The connections 263 connect a controller 261 to the ink 4 jet apparatus, for controlling the operation of the 5 latter.
6 In conventional operation of the ink jet 7 apparatus, the controller 261 is programmed to at an 8 appropriate time, via its connection to the printed 9 circuits 238, apply a voltage to a selected one or ones 10 of the hot electrodes 260 of the transducers 20~. The 11 applied voltage causes an electric field to be produced 12 transverse to the axis of elongation of the selected 13 transducers 204, causing the transducers 204 to con-14 tract along their elongated axis. When a particular 15 transducer 204 so contracts upon energization, the 16 portion of the diaphragm 210 located below the foot 207 17 of the transducer 204 moves in the direction of the 18 contracting transducer 204, thereby effectively expand-19 ing the volume of the associated chamber 200. As the 20 volume of the particular chamber 200 is so expanded, a 21 negative pressure is initially created within the cham-22 ber, causing ink therein to tend to move away from the 23 associated orifice 202, while simultaneously permit-24 ting ink from the reservoir 212 to flow through the 25 associated restricted opening or inlet 214 into the 26 chamber 200. The amount of ink that flows into the 27 chamber 200 during the refill is greater than the 28 amount that flows back out through the restrictor 214 29 during firing. The time between refill and fire is not 30 varied during operation of the jet thus providing a 31 "fill before fire" cycle. Shortly thereafter, the 32 controller 261 is programmed to remove the voltage or 33 drive signal from the particular one or ones of the 34 selected transducers 204, causing the transducer 204 or
35 transducers 204 to very rapidly expand along their 1 elongated axis, whereby via the visco-elastic tnaterial 2 208, and the feet 207, the transducers 204 push against 3 the rest of the diaphragm 210 beneath them, using a 4 rapid contraction or reduction of the volume of the 5 associated chamber or chambers 200. In turn, this 6 rapid reduction in the volume of the associated 7 chambers 200, creates a pressure pulse or positive 8 pressure disturbance within the chambers 200, causing 9 an ink droplet to be ejected from the associated ori-lO fices ~02. Note that when a selected transducer 204 is ll so energized, it both contracts or reduces its length 12 and increases its thickness. However, the increase in 13 thickness is of no consequence to the illustrated ink 14 jet apparatus, in that the changes in length of the 15 transducer control the operation of the individual ink 16 jets of the array. Also note, that with present tech-17 nology, by energizing the transducers for contraction 18 along their elongated axis, accelerated aging of the 19 transducers 20~ is avoided, and in extreme cases, de-20 polarization is also avoided~
21 As previously mentioned, the present invent-22 ors recognized that it is known that droplet size pro-23 duced by an impulse ink jet printer is closely coupled 24 to the orifice si~e of the associated ink jet device, 25 and that only small variations in droplet size can 26 generally be produced by varying the drive voltage 27 amplitude or waveform, or example. They further re-28 cognized that for high quality half-tone printing, the 29 droplet size must be controlable over a wide range.
30 They also recognized that for certain inks, which do 31 not spread widely on paper, such as a wax base inks, 32 for example, it is necessary to produce larger ink 33 droplets or obtaining desired print dot diameters 34 than can be readily achieved by the present methods of 35 operating ink jet apparatus.
~2d~7~4 ~?
1 In operating the illustrative ink jet device 2 previously described herein, the present inventors 3 discovered that by synchronously exciting either one or 4 a combination of the fluidic and mechanical resonant 5 frequencies of the ink jet apparatus for producing a 6 dominant resonant frequency disturbance within the 7 associated ink chamber and ink, permitting either one 8 of one-cycle, or one subharmonic cycle of the dominant 9 resonant frequency to be produced, that the volume oE
10 ink droplets ejected is controlable. They ~urther dis-11 covered that by repeating this operation in an itera-12 tive or successive manner, with each repetition cycle 13 being in synchronism with the dominant resonant fre-14 quency of the ink jet apparatus, a plurality of ink 15 droplets can be ejected within a time period permitting 16 the droplets to merge while airborne or upon the 17 recording medium, thereby permitting substantial con-18 trol over the resultant dot size upon the recording 19 medium relative to the dot size obtained from a single 20 droplet of ink. The resultant dot size is dependent 21 upon the number of times within a given time period 22 that the inventive method of operation is repeated.
23 Figure 12 shows nine droplets 301-309 in flight for 24 producing a dot on a recording medium using the method 25 of the present invention.
26 The present inventors further discovered 27 that for the illustrative ink jet device of this exam-28 ple, that the Helmholtz resonant frequency is the dom-29 inant resonant frequency of the subject ink jet device.
30 Other ink jet apparatus, which may also be operated 31 using the method of the present invention, may have 32 some other resonant frequency other than the Helmholtz 33 as-the dominant resonant frequency. For the purposes 34 of further describing and illustrating the method of J 12~7~
1 operation of the subject invention, it is assumed that 2 the Helmholtz resonant frequency is the dominant reson-3 ant frequency, but such assumption is not meant to be 4 limiting or restrictive as to the scope and use of the S present invention.
6 The present method is a multipulse method of 7 operating an ink jet apparatus, utilizing the dominant 8 resonant frequency of the ink jet device to produce 9 droplets of ink o~ controlable volume through pulsaion 10 of the transducer 204 (in this example) at a rep-11 etition rate of the dominant resonant frequency using 12 either a single, or a plurality of a pulses at the 13 dominant resonant frequency, dependent upon the dot 14 size required. Where the Helmholtz frequency is the 15 dominant frequency, this frequency results from an 16 interaction of the ink chamber 200 (in this example) 17 compliance, and the ink or fluid inertance expressed by 18 the formula:
2l0 FH= 1 ( ~
21 where C equals the ink chamber compliance, L is equal 22 to the inertance and I/L equals [I/L orifice + I/L
23 restrictor 214 (for example)].
24 Through laboratory test and analysis, it 25 was determined that the illustrative ink je-t apparatus 26 has a Helmholtz frequency of approximately 30 kHz. In 27 reference to Figure 4, the substantially rectangular or 28 square wave pulses shown were used to operate the il-29 lustrative ink jet device in accordance with the method 30 of the present invention. The pulse characteristics 31 for this particular waveform found to provide substan-32 tial control over the size of the ejected ink droplet 33 for the various time periods shown were discovered to J 12~7~ ~
1 be- Tl = 1.0 microsecond pulse time, T~ = 13.0 micro-2 seconds pulse time, T3 = 1.0 microsecond fall time, 3 and the dead time T4 = 15.0 microseconds, thereby pro-4 viding a pulse repetition frequency close to the 30 kHz 5 Helmholtz dominant resonant frequency of the illus-6 trative device. You will note that the dead time T 4, 7 in this example, is required to lock the drive signal 8 applied to a transducer 204 in phase with the natural 9 oscillation of the ink ~luid contained within the ink 10 chamber 200. The inventors determined that by apply-11 ing two pulses as shown in Figure 4 to a transducer 12 204, that the volume of the ultimate ink droplet eject-13 ed was approximately twice the volume obtained in using 14 a single one of the pulses over the same period of time 15 that the two pulses wexe applied. It was further deter-16 mined that the droplet volume appeared to increase 17 linearly in direct correspondence with the number of 18 such pulses applied to the transducer 204. By applying 19 two or more pulses of appropriate amplitude having the 20 waveshapes as shown in Figure 4 and characteristics as 21 previously described, it was further determined that 22 this multipulsing method resulted in a merging of the 23 ink droplets in flight, or upon striking the recording 24 medium, resulting in an increased dot size upon the recording medium compared to using a single pulse for 26 producing such a dot upon the medium.
27 Note that the waveform of ~igure 4, and the 28 waveforms of Figures 5-9, to be described later, can be 29 obtained under laboratory testing conditions from a 3~ commercial waveform generator. However, in a practical 31 device, controller 261, for example, must be specifi-32 cally designed or programmed to produce the desired 33 waveforms and number of pulses required for producing a 34 given size dot on a recording medium.
? 12 ~ 4 1 Tests conducted by the inventors demon-2 strated that the illustrative device, having a Helm-3 holtz frequency of 30 kHz, as previously mentioned, is 4 operable using any combination of pulse with T2 and 5 dead time T4 ranging from 8.0 microseconds to 16.0 6 microseconds, with the rise and fall times Tl, T3, 7 respectively, set at one microsecond, for example. The 8 lower limit of this range is determined by the reaction 9 time of the transducer(s) 20~, whereas the upper limit 10 of this range is determined by the ink jet device con-11 figuration limiting the effectiveness of driving or 12 operating the device at or near its Helmholtz fre-13 quency. The complexity of the electronic design of 14 the controller ~61 is reduced when the waveform of the 15 driving pulses such as in Figure 4 are substantially as 16 shown with the total pulse width (Tl ~ T2 + T3) and 17 dead time T4 being substantially equal in duration.
18 Also, optimum operation of the illustrative ink jet 19 apparatus was obtained when the total periodicity of 20 the pulse train (Tl + T2 + T3 + T4) is made substan-21 tially equal to the reciprocal of the dominant resonant 22 frequency, in this example l/FH. It was further det-23 ermined that the limitations on tne reaction time of 24 the transducer 204, coupled with the relatively high frequency of the dominant resonant frequency mode of 26 driving or operating the ink jet apparatus using the 27 multipulse method of this invention, that many other 28 different waveshapes other than those of Figure 4, but 29 having similar periodicity can be used. For example, 30 other waveshapes found to give satisfactory control 31 over the dot size using the method of the present in-32 vention included a sinewave, a half-sinewave, a 33 quarter-sinewave~ a sawtooth waveform and a triangular 34 waveform, as shown in Figures 5-9 respectively. In using such alternative waveforms to operate the illus-
21 As previously mentioned, the present invent-22 ors recognized that it is known that droplet size pro-23 duced by an impulse ink jet printer is closely coupled 24 to the orifice si~e of the associated ink jet device, 25 and that only small variations in droplet size can 26 generally be produced by varying the drive voltage 27 amplitude or waveform, or example. They further re-28 cognized that for high quality half-tone printing, the 29 droplet size must be controlable over a wide range.
30 They also recognized that for certain inks, which do 31 not spread widely on paper, such as a wax base inks, 32 for example, it is necessary to produce larger ink 33 droplets or obtaining desired print dot diameters 34 than can be readily achieved by the present methods of 35 operating ink jet apparatus.
~2d~7~4 ~?
1 In operating the illustrative ink jet device 2 previously described herein, the present inventors 3 discovered that by synchronously exciting either one or 4 a combination of the fluidic and mechanical resonant 5 frequencies of the ink jet apparatus for producing a 6 dominant resonant frequency disturbance within the 7 associated ink chamber and ink, permitting either one 8 of one-cycle, or one subharmonic cycle of the dominant 9 resonant frequency to be produced, that the volume oE
10 ink droplets ejected is controlable. They ~urther dis-11 covered that by repeating this operation in an itera-12 tive or successive manner, with each repetition cycle 13 being in synchronism with the dominant resonant fre-14 quency of the ink jet apparatus, a plurality of ink 15 droplets can be ejected within a time period permitting 16 the droplets to merge while airborne or upon the 17 recording medium, thereby permitting substantial con-18 trol over the resultant dot size upon the recording 19 medium relative to the dot size obtained from a single 20 droplet of ink. The resultant dot size is dependent 21 upon the number of times within a given time period 22 that the inventive method of operation is repeated.
23 Figure 12 shows nine droplets 301-309 in flight for 24 producing a dot on a recording medium using the method 25 of the present invention.
26 The present inventors further discovered 27 that for the illustrative ink jet device of this exam-28 ple, that the Helmholtz resonant frequency is the dom-29 inant resonant frequency of the subject ink jet device.
30 Other ink jet apparatus, which may also be operated 31 using the method of the present invention, may have 32 some other resonant frequency other than the Helmholtz 33 as-the dominant resonant frequency. For the purposes 34 of further describing and illustrating the method of J 12~7~
1 operation of the subject invention, it is assumed that 2 the Helmholtz resonant frequency is the dominant reson-3 ant frequency, but such assumption is not meant to be 4 limiting or restrictive as to the scope and use of the S present invention.
6 The present method is a multipulse method of 7 operating an ink jet apparatus, utilizing the dominant 8 resonant frequency of the ink jet device to produce 9 droplets of ink o~ controlable volume through pulsaion 10 of the transducer 204 (in this example) at a rep-11 etition rate of the dominant resonant frequency using 12 either a single, or a plurality of a pulses at the 13 dominant resonant frequency, dependent upon the dot 14 size required. Where the Helmholtz frequency is the 15 dominant frequency, this frequency results from an 16 interaction of the ink chamber 200 (in this example) 17 compliance, and the ink or fluid inertance expressed by 18 the formula:
2l0 FH= 1 ( ~
21 where C equals the ink chamber compliance, L is equal 22 to the inertance and I/L equals [I/L orifice + I/L
23 restrictor 214 (for example)].
24 Through laboratory test and analysis, it 25 was determined that the illustrative ink je-t apparatus 26 has a Helmholtz frequency of approximately 30 kHz. In 27 reference to Figure 4, the substantially rectangular or 28 square wave pulses shown were used to operate the il-29 lustrative ink jet device in accordance with the method 30 of the present invention. The pulse characteristics 31 for this particular waveform found to provide substan-32 tial control over the size of the ejected ink droplet 33 for the various time periods shown were discovered to J 12~7~ ~
1 be- Tl = 1.0 microsecond pulse time, T~ = 13.0 micro-2 seconds pulse time, T3 = 1.0 microsecond fall time, 3 and the dead time T4 = 15.0 microseconds, thereby pro-4 viding a pulse repetition frequency close to the 30 kHz 5 Helmholtz dominant resonant frequency of the illus-6 trative device. You will note that the dead time T 4, 7 in this example, is required to lock the drive signal 8 applied to a transducer 204 in phase with the natural 9 oscillation of the ink ~luid contained within the ink 10 chamber 200. The inventors determined that by apply-11 ing two pulses as shown in Figure 4 to a transducer 12 204, that the volume of the ultimate ink droplet eject-13 ed was approximately twice the volume obtained in using 14 a single one of the pulses over the same period of time 15 that the two pulses wexe applied. It was further deter-16 mined that the droplet volume appeared to increase 17 linearly in direct correspondence with the number of 18 such pulses applied to the transducer 204. By applying 19 two or more pulses of appropriate amplitude having the 20 waveshapes as shown in Figure 4 and characteristics as 21 previously described, it was further determined that 22 this multipulsing method resulted in a merging of the 23 ink droplets in flight, or upon striking the recording 24 medium, resulting in an increased dot size upon the recording medium compared to using a single pulse for 26 producing such a dot upon the medium.
27 Note that the waveform of ~igure 4, and the 28 waveforms of Figures 5-9, to be described later, can be 29 obtained under laboratory testing conditions from a 3~ commercial waveform generator. However, in a practical 31 device, controller 261, for example, must be specifi-32 cally designed or programmed to produce the desired 33 waveforms and number of pulses required for producing a 34 given size dot on a recording medium.
? 12 ~ 4 1 Tests conducted by the inventors demon-2 strated that the illustrative device, having a Helm-3 holtz frequency of 30 kHz, as previously mentioned, is 4 operable using any combination of pulse with T2 and 5 dead time T4 ranging from 8.0 microseconds to 16.0 6 microseconds, with the rise and fall times Tl, T3, 7 respectively, set at one microsecond, for example. The 8 lower limit of this range is determined by the reaction 9 time of the transducer(s) 20~, whereas the upper limit 10 of this range is determined by the ink jet device con-11 figuration limiting the effectiveness of driving or 12 operating the device at or near its Helmholtz fre-13 quency. The complexity of the electronic design of 14 the controller ~61 is reduced when the waveform of the 15 driving pulses such as in Figure 4 are substantially as 16 shown with the total pulse width (Tl ~ T2 + T3) and 17 dead time T4 being substantially equal in duration.
18 Also, optimum operation of the illustrative ink jet 19 apparatus was obtained when the total periodicity of 20 the pulse train (Tl + T2 + T3 + T4) is made substan-21 tially equal to the reciprocal of the dominant resonant 22 frequency, in this example l/FH. It was further det-23 ermined that the limitations on tne reaction time of 24 the transducer 204, coupled with the relatively high frequency of the dominant resonant frequency mode of 26 driving or operating the ink jet apparatus using the 27 multipulse method of this invention, that many other 28 different waveshapes other than those of Figure 4, but 29 having similar periodicity can be used. For example, 30 other waveshapes found to give satisfactory control 31 over the dot size using the method of the present in-32 vention included a sinewave, a half-sinewave, a 33 quarter-sinewave~ a sawtooth waveform and a triangular 34 waveform, as shown in Figures 5-9 respectively. In using such alternative waveforms to operate the illus-
36 trative device, as previously mentioned, the 30 kHz ~ ~2~7~
1 Helmholtz frequency of the device was determined to be 2 the dominant frequency. Accordingly, for the sinusoid-3 al waveform of Figure 5, 1/2 Ts can be substantially 4 made equal to 30 kHz. Similarly, for the half-wave 5 sinusoidal waveform of Figure 6, the pulse time T6 and 6 dead time T7 should equal about 15 microseconds.
7 Similar comments can be made for the pulse times Tg, 8 Tlo, T12, of Figures 7-9 respectively, and of the dead 9 time Tg~ Tll and T13, of ~igures 7-9, respectively.
From the various pulse shapes or waveforms 11 tested, it was discovered that the rectangular or 12 square waveform~ due apparently to having fast rise 13 and fall times, can be utilized at a much lower pulse 14 voltage amplitude than any other waveforms tested such 15 as those of ~igures 5-9, for example. In fact, it was 16 determined that the quarter-wave sinusoidal waveorm of 17 Figure 7 required pulses of 20% greater amplitude than 18 the substantially square or rectangular pulses of 19 Figure 4 for obtaining equivalent printing operation 20 from the illustrated ink ~et device. ~lso, as prev-21 iously mentioned, the waveform of Figure 4 generally is 22 much easier to provide electronically relative to the 23 other waveforms of Figures 5-9, and yet other difEerent 24 waveforms.
It was Eurther discovered in testing the 26 method o the present invention and operating the illus-27 trative ink jet device, that due to the dominance of 28 the Helmholtz frequency in the device tested, that the 29 multipulsing method of the present invention can also 30 be provided by basing the periodicity of the driving 31 pulses upon subharmonic cycles of the Helmholtz fre-32 quency. It is believed that the same result would be 33 obtained for the dominant resonant frequency of some 34 other ink jet device, had it been tested using the L7~
1 method of the present invention. However, using the 2 example of a 30 kHz Helmholtz dominant frequency in a 3 particular ink jet apparatus, a subharmonic frequency 4 would result in drive pulse widths which would be very large, causing an undesirable reduction in the usable 6 print frequency of the particular device or ink iet 7 apparatus. Accordingly, the present inventors tested 8 an ink jet apparatus similar to the illustrative device 9 but having a smaller ink chamber 200 (relatively lower compliance) Eor providing a Helmholtz resonant fre-11 quency of about 100 kHz. The method oE the present 12 invention operated this device with satisfactory print-13 ing using multipulses having a 30 microsecond period-14 icity, corresponding to the third subharmonic of the 100 kHz Helmholtz dominant resonant frequency. Multi-16 pulses having a periodicity made subharmonic to 10017 kHz, for example of 20 kHz were tested, but performance 18 at this subharmonic level was found to be relatively 19 poor.
In Figure 10, bands of successive dots were 21 printed using a successively higher number of multi-22 pulses for printing each dot in the bands shown in 23 views (A) through print (F), respectively. The multi-24 pulses used in producing the bands of dots in Figure 10 were quarter-wave sinusoids as shown in Figure 7, with 26 pulse times T8and dead times Tg each oE 15 micro-27 seconds. The voltage amplitude of the pulses was held 28 constant at about 33 volts. In the band of dots of 29 view (A) only one such pulse was used for obtaining the dots shown. The dots of the band shown in view (B) 31 were produced over the same cycle time as those in view 32 tA) but two multipulses were used for producing each 33 dot of the former rather than one. Similarly, the dots 34 of bands shown in views (C) through (F) were produced using 3, 4, 5 and 6 multipulses, respectively, tnrough ~J 12 ~ ~71~
1 an equivalent cycle of time for printing each dot.
2 Accordingly, as would be expected, the bands of view 3 (A) through (F) are successively bolder because of the 4 successively greater dot size obtained via the multi-5 pulsing method of the present invention.
6 Similar multipulses were used in producing 7 the font sets of successively greater boldness in views 8 (A) through (C) of Figure 11. The characters printed 9 in view (A) re~uired one drive pulse to produce each 10 dot forming a given character, whereas two pulses were 11 used for producing each one of the individual dots of 12 the font of view (B), and three pulses were used in 13 producing each individual dot forming the font char-14 acters of view (C).
In summation of the opera-tion of the pres-16 ent invention, in operating an ink jet printing device 17 to produce a printed dot upon a recording medium, a 18 given period of time dependent upon the ink jet print-19 ing system is allotted for providing the ink droplet or 20 droplets to print the dot on the recording medium. The 21 boldness of a given dot can be controlled by control-22 ling the volume of ink or number of ink droplets eject-23 ed from the ink jet device over the allotted time for 24 producing that dot. The present invention provides a 25 method of operating an ink jet device using one or a 26 multiple number of drive pulses for operating the de-27 vice over a given dot production time for producing ink 28 droplets, each of a known volume of ink, by carefully 29 controlling the shape and periodicity of the drive 30 pulses utilized, whereby the periodicity of the drive 31 pulses utili~ed is made substantially equivalent to the 32 dominant resonant frequency of the ink jet device.
, ~2~4~1~
1 The controller 261 can be provided by hard-2 wired logic, or by microprocessor programmed for pro-3 viding the necessary control functions, or by some 4 combination of the two, Eor example~ Note that a Wave-5 tek Model 175 waveshape generator, manufactured by 6 Wavete~, San Diego, California was used by the present 7 inventors to obtain the waveforms shown in Figures 1-9.
8 In a practical system, a controller 261 would typically g be designed for providing the necessary waveforms and 10 functions, as previously mentioned, Eor each particular 11 application 12 Although particular embodiments oE the pres-13 ent inventive method for operating an ink jet appara-14 tus have been disclosed, other embodiments which fall 15 within the true spirit and scope of the appended claims 16 may occur to those of ordinary skill in the art.
1 Helmholtz frequency of the device was determined to be 2 the dominant frequency. Accordingly, for the sinusoid-3 al waveform of Figure 5, 1/2 Ts can be substantially 4 made equal to 30 kHz. Similarly, for the half-wave 5 sinusoidal waveform of Figure 6, the pulse time T6 and 6 dead time T7 should equal about 15 microseconds.
7 Similar comments can be made for the pulse times Tg, 8 Tlo, T12, of Figures 7-9 respectively, and of the dead 9 time Tg~ Tll and T13, of ~igures 7-9, respectively.
From the various pulse shapes or waveforms 11 tested, it was discovered that the rectangular or 12 square waveform~ due apparently to having fast rise 13 and fall times, can be utilized at a much lower pulse 14 voltage amplitude than any other waveforms tested such 15 as those of ~igures 5-9, for example. In fact, it was 16 determined that the quarter-wave sinusoidal waveorm of 17 Figure 7 required pulses of 20% greater amplitude than 18 the substantially square or rectangular pulses of 19 Figure 4 for obtaining equivalent printing operation 20 from the illustrated ink ~et device. ~lso, as prev-21 iously mentioned, the waveform of Figure 4 generally is 22 much easier to provide electronically relative to the 23 other waveforms of Figures 5-9, and yet other difEerent 24 waveforms.
It was Eurther discovered in testing the 26 method o the present invention and operating the illus-27 trative ink jet device, that due to the dominance of 28 the Helmholtz frequency in the device tested, that the 29 multipulsing method of the present invention can also 30 be provided by basing the periodicity of the driving 31 pulses upon subharmonic cycles of the Helmholtz fre-32 quency. It is believed that the same result would be 33 obtained for the dominant resonant frequency of some 34 other ink jet device, had it been tested using the L7~
1 method of the present invention. However, using the 2 example of a 30 kHz Helmholtz dominant frequency in a 3 particular ink jet apparatus, a subharmonic frequency 4 would result in drive pulse widths which would be very large, causing an undesirable reduction in the usable 6 print frequency of the particular device or ink iet 7 apparatus. Accordingly, the present inventors tested 8 an ink jet apparatus similar to the illustrative device 9 but having a smaller ink chamber 200 (relatively lower compliance) Eor providing a Helmholtz resonant fre-11 quency of about 100 kHz. The method oE the present 12 invention operated this device with satisfactory print-13 ing using multipulses having a 30 microsecond period-14 icity, corresponding to the third subharmonic of the 100 kHz Helmholtz dominant resonant frequency. Multi-16 pulses having a periodicity made subharmonic to 10017 kHz, for example of 20 kHz were tested, but performance 18 at this subharmonic level was found to be relatively 19 poor.
In Figure 10, bands of successive dots were 21 printed using a successively higher number of multi-22 pulses for printing each dot in the bands shown in 23 views (A) through print (F), respectively. The multi-24 pulses used in producing the bands of dots in Figure 10 were quarter-wave sinusoids as shown in Figure 7, with 26 pulse times T8and dead times Tg each oE 15 micro-27 seconds. The voltage amplitude of the pulses was held 28 constant at about 33 volts. In the band of dots of 29 view (A) only one such pulse was used for obtaining the dots shown. The dots of the band shown in view (B) 31 were produced over the same cycle time as those in view 32 tA) but two multipulses were used for producing each 33 dot of the former rather than one. Similarly, the dots 34 of bands shown in views (C) through (F) were produced using 3, 4, 5 and 6 multipulses, respectively, tnrough ~J 12 ~ ~71~
1 an equivalent cycle of time for printing each dot.
2 Accordingly, as would be expected, the bands of view 3 (A) through (F) are successively bolder because of the 4 successively greater dot size obtained via the multi-5 pulsing method of the present invention.
6 Similar multipulses were used in producing 7 the font sets of successively greater boldness in views 8 (A) through (C) of Figure 11. The characters printed 9 in view (A) re~uired one drive pulse to produce each 10 dot forming a given character, whereas two pulses were 11 used for producing each one of the individual dots of 12 the font of view (B), and three pulses were used in 13 producing each individual dot forming the font char-14 acters of view (C).
In summation of the opera-tion of the pres-16 ent invention, in operating an ink jet printing device 17 to produce a printed dot upon a recording medium, a 18 given period of time dependent upon the ink jet print-19 ing system is allotted for providing the ink droplet or 20 droplets to print the dot on the recording medium. The 21 boldness of a given dot can be controlled by control-22 ling the volume of ink or number of ink droplets eject-23 ed from the ink jet device over the allotted time for 24 producing that dot. The present invention provides a 25 method of operating an ink jet device using one or a 26 multiple number of drive pulses for operating the de-27 vice over a given dot production time for producing ink 28 droplets, each of a known volume of ink, by carefully 29 controlling the shape and periodicity of the drive 30 pulses utilized, whereby the periodicity of the drive 31 pulses utili~ed is made substantially equivalent to the 32 dominant resonant frequency of the ink jet device.
, ~2~4~1~
1 The controller 261 can be provided by hard-2 wired logic, or by microprocessor programmed for pro-3 viding the necessary control functions, or by some 4 combination of the two, Eor example~ Note that a Wave-5 tek Model 175 waveshape generator, manufactured by 6 Wavete~, San Diego, California was used by the present 7 inventors to obtain the waveforms shown in Figures 1-9.
8 In a practical system, a controller 261 would typically g be designed for providing the necessary waveforms and 10 functions, as previously mentioned, Eor each particular 11 application 12 Although particular embodiments oE the pres-13 ent inventive method for operating an ink jet appara-14 tus have been disclosed, other embodiments which fall 15 within the true spirit and scope of the appended claims 16 may occur to those of ordinary skill in the art.
Claims (9)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method for operating an ink jet appar-atus for controlling the dot size of ink printed upon a recording medium, said ink jet apparatus including transducer means operable for producing a positive pressure disturbance within an associated ink chamber filled with ink, for ejecting an ink droplet from an associated orifice, the method comprising the steps of:
(1) operating said transducer means for synchronously exciting either one or a combination of fluid or mechanical resonant frequencies of said ink jet apparatus for producing a dominant resonant freq-uency within said ink chamber and associated ink; and (2) permitting either one of one cycle, or one subharmonic cycle of said dominant resonant fre-quency to be produced, for substantially predictably controlling the volume of an ink droplet ejected from said orifice via the resultant pressure disturbance produced in said chamber.
(1) operating said transducer means for synchronously exciting either one or a combination of fluid or mechanical resonant frequencies of said ink jet apparatus for producing a dominant resonant freq-uency within said ink chamber and associated ink; and (2) permitting either one of one cycle, or one subharmonic cycle of said dominant resonant fre-quency to be produced, for substantially predictably controlling the volume of an ink droplet ejected from said orifice via the resultant pressure disturbance produced in said chamber.
2. The method of claim 1, further including the steps of successively repeating steps (1) and (2) a desired number of times, in synchronism with said dom-inant resonant frequency, for producing a plurality of ink droplets within a time period permitting said drop lets to merge while airborne or upon the recording medium, for controlably increasing the resultant dot size upon said recording medium relative to the dot size obtained from a single droplet of ink.
3. The method of claim 1, wherein said transducer means is responsive to an electrical signal for producing said pressure disturbance, whereby step (1) further includes the steps of:
making the period of said electrical signal substantially equal to either one of the period of the Helmholtz resonant frequency, or the period of a sub-harmonic of said Helmholtz frequency; and applying said electrical signal to said transducer.
making the period of said electrical signal substantially equal to either one of the period of the Helmholtz resonant frequency, or the period of a sub-harmonic of said Helmholtz frequency; and applying said electrical signal to said transducer.
4. The method of claim 2, wherein said transducer means is responsive to an electrical signal for producing said pressure disturbance, whereby step (1) further includes the steps of:
making the period of said electrical signal substantially equal to either one of the period of the Helmholtz resonant frequency, or the period of a sub-harmonic of said Helmholtz frequency; and applying said electrical signal to said transducer.
making the period of said electrical signal substantially equal to either one of the period of the Helmholtz resonant frequency, or the period of a sub-harmonic of said Helmholtz frequency; and applying said electrical signal to said transducer.
5. The method of claims 3 or 4, further including the step of shaping said electrical signal to be substantially a pulse having an exponential leading edge, and a step-like trailing edge.
6. The method of claim 2, wherein said transducer means is responsive to an electrical signal for producing said pressure disturbance, whereby step 1 further includes the steps of:
shaping said electrical signal substantially as either one of a square wave, a rectangular wave, a triangular wave, a half-wave sinusoidal waveform, a full-wave sinusoidal waveform, a quarter-wave sinusoidal waveform, less than a quarter-wave sinusoidal waveform, or a pulse having an exponential leading edge and a step-like trailing edge; and applying said electrical signal to said transducer.
shaping said electrical signal substantially as either one of a square wave, a rectangular wave, a triangular wave, a half-wave sinusoidal waveform, a full-wave sinusoidal waveform, a quarter-wave sinusoidal waveform, less than a quarter-wave sinusoidal waveform, or a pulse having an exponential leading edge and a step-like trailing edge; and applying said electrical signal to said transducer.
7. The method of claim 6, further including the step of making the period of said electrical signal substantially equal to either one or a combination of the period(s) of selected fluidic and mechanical resonant frequencies of said ink jet apparatus.
8. The method of claim 7, further including the step of selectively gating said electrical signal "on" and "off" for controlling the dot size of each individual ink droplets.
9. The method of claim 8, wherein the period of said electrical signal is made substantially equal to either one of the period of the Helmholtz resonant frequency of said ink jet apparatus, or the period of a subharmonic of said Helmholtz frequency.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US60078584A | 1984-04-16 | 1984-04-16 | |
| US600,785 | 1990-10-22 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1244714A true CA1244714A (en) | 1988-11-15 |
Family
ID=24405027
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000476889A Expired CA1244714A (en) | 1984-04-16 | 1985-03-19 | Method for selective multi-cycle resonant operation of an ink jet apparatus for controlling dot size |
Country Status (8)
| Country | Link |
|---|---|
| JP (1) | JPH0655513B2 (en) |
| CA (1) | CA1244714A (en) |
| CH (1) | CH667044A5 (en) |
| DE (1) | DE3513442C2 (en) |
| FR (1) | FR2562838B1 (en) |
| GB (1) | GB2157623B (en) |
| IT (1) | IT1184441B (en) |
| NL (1) | NL8501112A (en) |
Families Citing this family (20)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0422870B1 (en) | 1989-10-10 | 1995-01-11 | Xaar Limited | Method of multi-tone printing |
| US5512922A (en) * | 1989-10-10 | 1996-04-30 | Xaar Limited | Method of multi-tone printing |
| JPH08336970A (en) * | 1995-04-14 | 1996-12-24 | Seiko Epson Corp | Ink-jet type recording device |
| JPH09300613A (en) * | 1996-03-15 | 1997-11-25 | Hitachi Koki Co Ltd | Driving method for on-demand type multinozzle ink-jet head |
| CA2264038A1 (en) * | 1996-08-27 | 1998-03-05 | Topaz Technologies, Inc. | Inkjet print head for producing variable volume droplets of ink |
| JPH10278256A (en) * | 1997-04-01 | 1998-10-20 | Minolta Co Ltd | Ink-jet recording device |
| KR100589987B1 (en) | 1997-05-15 | 2006-06-14 | 자아 테크날러쥐 리미티드 | Operation of droplet deposition apparatus |
| GB2338928B (en) | 1998-07-02 | 2000-08-09 | Tokyo Electric Co Ltd | A driving method of an ink-jet head |
| GB2338927B (en) * | 1998-07-02 | 2000-08-09 | Tokyo Electric Co Ltd | A driving method of an ink-jet head |
| JP2000326511A (en) * | 1999-05-18 | 2000-11-28 | Nec Corp | Driving method for ink jet recording head and circuit thereof |
| JP2001186880A (en) * | 1999-10-22 | 2001-07-10 | Ngk Insulators Ltd | Method for producing dna chip |
| US6656432B1 (en) * | 1999-10-22 | 2003-12-02 | Ngk Insulators, Ltd. | Micropipette and dividedly injectable apparatus |
| JP3920596B2 (en) | 2001-06-25 | 2007-05-30 | 東芝テック株式会社 | Inkjet recording apparatus and inkjet recording method |
| JP4730516B2 (en) * | 2005-02-22 | 2011-07-20 | ブラザー工業株式会社 | Ink droplet ejection apparatus and ink droplet ejection method |
| JP4720226B2 (en) * | 2005-03-15 | 2011-07-13 | 富士ゼロックス株式会社 | Droplet discharge recording head driving method and droplet discharge recording apparatus |
| JP4764038B2 (en) * | 2005-03-17 | 2011-08-31 | 東芝テック株式会社 | Driving method of ink jet recording apparatus |
| US7988247B2 (en) * | 2007-01-11 | 2011-08-02 | Fujifilm Dimatix, Inc. | Ejection of drops having variable drop size from an ink jet printer |
| JP2007230243A (en) * | 2007-05-07 | 2007-09-13 | Seiko Epson Corp | Method for controlling liquid jet device |
| WO2012081472A1 (en) | 2010-12-16 | 2012-06-21 | コニカミノルタホールディングス株式会社 | Inkjet recording device and method for generating drive waveform signal |
| EP2998119B1 (en) | 2013-05-13 | 2020-12-23 | Konica Minolta, Inc. | Inkjet head, method for driving same, and inkjet printer |
Family Cites Families (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3893131A (en) * | 1973-09-04 | 1975-07-01 | Xerox Corp | Ink printer |
| US3977007A (en) * | 1975-06-02 | 1976-08-24 | Teletype Corporation | Gray tone generation |
| US4087825A (en) * | 1976-05-27 | 1978-05-02 | International Business Machines Corporation | Ink jet printing intensity modulation |
| JPS5311532A (en) * | 1976-07-19 | 1978-02-02 | Sanyo Electric Co Ltd | Printing system |
| US4281333A (en) * | 1979-02-14 | 1981-07-28 | Nippon Electric Co., Ltd. | Ink-on-demand type ink-jet printer with coordinated variable size drops with variable charges |
| JPS55131882A (en) * | 1979-04-02 | 1980-10-14 | Canon Inc | Electronic equipment |
| JPS5655261A (en) * | 1979-10-13 | 1981-05-15 | Ricoh Co Ltd | Ink jet printer |
| JPS57188372A (en) * | 1981-01-30 | 1982-11-19 | Exxon Research Engineering Co | Ink jet device |
| IT1155548B (en) * | 1982-07-16 | 1987-01-28 | Olivetti & Co Spa | PILOTING SYSTEM OF A SELECTIVE INK JET WRITING ELEMENT |
| DE3381406D1 (en) * | 1982-12-27 | 1990-05-10 | Dataproducts Corp | OPERATING AN INK JET. |
| US4503444A (en) * | 1983-04-29 | 1985-03-05 | Hewlett-Packard Company | Method and apparatus for generating a gray scale with a high speed thermal ink jet printer |
-
1985
- 1985-03-19 CA CA000476889A patent/CA1244714A/en not_active Expired
- 1985-04-15 FR FR8505625A patent/FR2562838B1/en not_active Expired
- 1985-04-15 CH CH1604/85A patent/CH667044A5/en not_active IP Right Cessation
- 1985-04-15 IT IT20331/85A patent/IT1184441B/en active
- 1985-04-15 DE DE3513442A patent/DE3513442C2/en not_active Expired - Lifetime
- 1985-04-16 JP JP60079432A patent/JPH0655513B2/en not_active Expired - Lifetime
- 1985-04-16 GB GB8509702A patent/GB2157623B/en not_active Expired
- 1985-04-16 NL NL8501112A patent/NL8501112A/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| DE3513442A1 (en) | 1985-10-17 |
| CH667044A5 (en) | 1988-09-15 |
| FR2562838A1 (en) | 1985-10-18 |
| JPS6122959A (en) | 1986-01-31 |
| GB8509702D0 (en) | 1985-05-22 |
| IT8520331A0 (en) | 1985-04-15 |
| GB2157623A (en) | 1985-10-30 |
| IT1184441B (en) | 1987-10-28 |
| GB2157623B (en) | 1989-05-04 |
| NL8501112A (en) | 1985-11-18 |
| FR2562838B1 (en) | 1988-01-15 |
| JPH0655513B2 (en) | 1994-07-27 |
| DE3513442C2 (en) | 1998-06-04 |
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