EP0622198A2 - Dispositif d'écriture thermique - Google Patents

Dispositif d'écriture thermique Download PDF

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Publication number
EP0622198A2
EP0622198A2 EP94302813A EP94302813A EP0622198A2 EP 0622198 A2 EP0622198 A2 EP 0622198A2 EP 94302813 A EP94302813 A EP 94302813A EP 94302813 A EP94302813 A EP 94302813A EP 0622198 A2 EP0622198 A2 EP 0622198A2
Authority
EP
European Patent Office
Prior art keywords
nozzle
resistive heating
ink
thickness
center
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
EP94302813A
Other languages
German (de)
English (en)
Other versions
EP0622198B1 (fr
EP0622198A3 (fr
Inventor
Clayton L. Holstun
Kenneth J. Courian
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.)
HP Inc
Original Assignee
Hewlett Packard Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hewlett Packard Co filed Critical Hewlett Packard Co
Publication of EP0622198A2 publication Critical patent/EP0622198A2/fr
Publication of EP0622198A3 publication Critical patent/EP0622198A3/fr
Application granted granted Critical
Publication of EP0622198B1 publication Critical patent/EP0622198B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
    • B41J2/01—Ink jet
    • B41J2/135—Nozzles
    • B41J2/14—Structure thereof only for on-demand ink jet heads
    • B41J2/14016—Structure of bubble jet print heads
    • B41J2/14032—Structure of the pressure chamber
    • B41J2/1404—Geometrical characteristics
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
    • B41J2/01—Ink jet
    • B41J2/135—Nozzles
    • B41J2/14—Structure thereof only for on-demand ink jet heads
    • B41J2002/14387—Front shooter

Definitions

  • the present invention relates to thermal ink-jet pens employed in thermal ink-jet printers, and, more particularly, to improving the performance of such pens employing an ink which includes a polymer to aid in dispersion of a pigment colorant.
  • the art of thermal ink-jet printing it is known to provide a plurality of electrically resistive elements on a common substrate for the purpose of heating a corresponding plurality of ink volumes contained in adjacent ink reservoirs leading to the ink ejection and printing process.
  • the adjacent ink reservoirs are typically provided as cavities, or firing chambers, in a barrier layer attached to the substrate for properly isolating mechanical energy to predefined volumes of ink.
  • the mechanical energy results from the conversion of electrical energy supplied to the resistive elements which creates a rapidly expanding vapor bubble in the ink above the resistive elements.
  • a plurality of ink ejection orifices are provided above these cavities in a nozzle plate and provide exit paths for ink during the printing process.
  • thermal ink-jet printheads In the operation of thermal ink-jet printheads, it is necessary to provide a flow of ink to the thermal, or resistive, element causing ink drop ejection. This has been accomplished by manufacturing ink fill channels, or slots, in the substrate, ink barrier, or nozzle plate.
  • Water-based inks commonly employ one or more water-soluble dyes as the colorant.
  • the colorant is a dye molecule that is dissolved in water.
  • Such inks typically include the dye, water, at least one co-solvent (an organic water-miscible solvent, such as diethylene glycol), and minor amounts of other substances, such as biocides.
  • Recent ink formulations have been developed, which contain pigments as colorants instead of water-soluble dyes. It is imperative to maintain these pigments in a dispersed form, because the pigments are particles, and would otherwise tend to settle with time.
  • the particles are held in dispersion by polymers called polymer dispersants.
  • These polymer dispersants have functional groups; one functionality on the polymer is hydrophobic and associates with the pigment, while another functionality on the polymer is hydrophilic and associates with water.
  • the polymer is of a length sufficient to keep the pigment particles separated. Examples of such pigment-polymer systems for ink-jet printers are disclosed, for example, in U.S. Patent 5,085,698, issued to S.-H. Ma et al on February 4, 1992.
  • Inks which contain polymers tend to be more cohesive than inks not containing polymers. This property allows the tail of an ink drop to stay together and remain attached to the meniscus longer, and move to the paper essentially intact. This tends to reduce the amount of random spray which lands on the paper, and is a positive benefit.
  • one of the consequences of this is that if the tail stays attached to the ink inside the cavity, a perturbation of the ink in the cavity due to the ink refilling or secondary bubble expansion, etc., can disturb the tail. In such an event, a small drop can separate from the back end of the tail. This satellite drop is large enough that it adversely affects the print quality.
  • a method for reducing spray (or satellite drops) in thermal ink-jet pens firing inks containing polymer dispersants comprises increasing the distance between the firing resistor and the nozzle. More correctly, it is the distance between the firing resistor and the ink meniscus that is increased.
  • the increase in distance may be done by offsetting the resistor with respect to the nozzle, or increasing the thickness of the orifice plate, or increasing the thickness of the barrier layer which defines the firing chamber and supports the nozzle plate, or recessing the resistor deeper into the substrate on which it is supported. Any or all of the foregoing may be implemented to reduce spray.
  • Thicker top plates tend to eliminate these spurious drops completely, or reduce their size.
  • offsetting the nozzle relative to the resistor in the pen scanning direction also suppresses the formation of the satellite drop. A combination of the two is particularly efficacious.
  • FIG. 1 depicts a series of horizontal lines fired by a single nozzle in a thermal ink-jet pen having an ink which includes a pigment-polymer system.
  • the horizontal lines show a pattern of regular "satellite" dots extending beyond the end of the line. These satellite dots are spaced about the same distance apart as the main drops. They can happen on either the odd or the even nozzles, but not generally from both odd and even on a single pen, and often just from some nozzles.
  • odd nozzles refers to one column of nozzles in a dual-column pen.
  • the term “even nozzles” refers to the other column.
  • FIG. 2 depicts a plot consisting of vertical lines extending the length of the page. The plot was generated by just the odd nozzles firing. FIG. 2 shows that a single firing would produce a main drop and a satellite drop. From this, it may be inferred that these satellites are formed even when a drop is fired with the meniscus stationary at its equilibrium position. Thus, all frequency-dependent refill considerations may be ignored. This means that aspects of the internal pen architecture relating to barrier inlet shape and shelf length are not significant contributors to the problem.
  • FIG. 3 shows an enlargement of a printed sample. Due to the spray, the print quality is deemed unacceptable.
  • the present invention is directed to reducing that spray.
  • FIGS. 4A-F depict in time sequence what is believed to be happening to generate the satellite dots when using an ink containing a pigment-polymer system.
  • the Figures depict a side elevational view of one firing resistor 10 and associated nozzle 12 in a nozzle plate 14 .
  • the resistor 10 is supported on a substrate 16 .
  • a barrier layer 18 defines the firing chamber 20 in which the resistor 10 resides, and is seen to the left and right of the resistor, forming two walls, 18a and 18b .
  • a further barrier wall (18c shown in FIG. 5) is "above" the plane of the Figure; the three barrier walls 18a, 18b, 18c define three sides of the firing chamber 20 , leaving a fourth wall open.
  • Ink 22 enters the firing chamber 20 from an ink feed slot (not shown in FIGS. 4A-F, denoted 21 in FIG. 5), which is in slot form and supplies ink to a plurality of resistors on either side (one side is the "even” side, and the other side is the “odd” side) from a reservoir (not shown) beneath the substrate 16 .
  • the ink feed slot fluidically communicates with the firing chamber 20 by means of a barrier inlet channel 23.
  • the barrier inlet channel 23 connects with the firing chamber 20 through the open wall and thus is "below" the plane of the Figure.
  • FIG. 5 is a top plan view of firing resistor 10 in the firing chamber 20 , together with the barrier walls 18a, 18b, 18c and the ink feed slot 21 .
  • FIG. 4A depicts ink in the equilibrium state.
  • the meniscus of the ink 22 retracts into the firing chamber 20 to make up for the ink that is forming the head 22a and tail 22b (FIGS. 4C, 4D).
  • the tail stays attached to the meniscus as it does this.
  • the firing bubble 24 is collapsing.
  • FIG. 4E computer simulations and physical observations suggest that its pressure increases and it re-expands slightly (FIG. 4E). This secondary expansion can cause a secondary jet 10 to 20 ⁇ sec after the first jet.
  • This secondary jet can impact on the underside of the nozzle plate 14 ; emerge, and hit the tail of the main drop, causing it to break up early; or make it all the way to the print medium (not shown) itself. But, in the present case, all the re-expansion has to do is disturb the symmetric nature of the meniscus (FIG. 4E). Since the tail is still attached to the meniscus, it gets “pushed" off-axis as as shown by portion 22c . The surface tension forces in the tail are then imbalanced, and the tail begins to roll up from the break-off point until a large enough volume separates and forms the satellite (FIG. 4F) from portion 22c .
  • Dye-based inks exhibit this problem as well, but not to the same degree. These inks tend to separate from the meniscus earlier, and so are less susceptible to bubble rebound. Their tails are also thinner, so there is less ink around to feed a satellite when the tail is pushed off-axis. Thus, the problem seen with pigment-polymer ink systems was not observed with aqueous dye-based ink systems.
  • the dimension between the top of the nozzle plate 14 and the resistor 10 is increased from about 50 ⁇ m to 60 ⁇ m, or by about 10 ⁇ m. This can be done by (1) offsetting the nozzle 12 with respect to the resistor 10 , (2) making the nozzle plate thicker, (3) making the barrier layer 18 thicker, or (4) etching out a "pit" in the floor of the firing chamber 20 in which the resistor is placed. Any combination of these approaches may also be employed.
  • the retracted meniscus 22 is increased. More specifically, the retracted meniscus location is raised relative to the resistor surface in order to keep it away from the re-expanding ink bubble. Thicker orifice plates, thicker barrier layer, or recessing the resistor would accomplish the goal of increasing this distance. Nozzle offset can help move the meniscus location away from the location of a re-expanding bubble. Also, increasing the firing chamber volume itself can reduce the amount of meniscus retraction, thereby effecting the same goal.
  • FIG. 5 depicts the default condition, as well as the direction of offset between the center of the resistor 10 and the orifice 12 (shown in phantom). Negative offset is in the scanning direction of the pen, produced by moving the nozzle towards the ink feed slot 21 .
  • FIGS. 6A-G depict firing all resistors with the pen in a stationary position.
  • FIG. 6A is with +4 ⁇ m offset, by which is meant that the nozzles 12 were moved 4 ⁇ m closer to the third wall 18a of the firing chamber 20 .
  • FIG. 6B is with zero offset, which is what is presently commercially employed in thermal ink-jet pens
  • FIGS. 6C-G are with -4, -8, -12, -16, and -20 ⁇ m offset, respectively, by which is meant that the nozzles were offset in the direction of the ink feed slot 21 .
  • the offset ranges from between 0 offset and -12 ⁇ m (in the direction of the ink feed slot).
  • the offset ranges from about -4 to -8 ⁇ m.
  • FIGS. 7A-D each depict a plurality of vertical lines, printed from pens in which the nozzle plate 14 was 48 ⁇ m thick (FIG. 7A), 53 ⁇ m thick (FIG. 7B), 57 ⁇ m thick (FIG. 7C), and 61 ⁇ m thick (FIG. 7D).
  • FIGS. 8A-D While either nozzle offset or thicker nozzle plates alone can significantly reduce satellite dots, a combination of the two gives the best performance, as shown in FIGS. 8A-D.
  • the same nozzle plate thicknesses were employed as in FIGS. 7A-D; in this case, the nozzle offset was -4 ⁇ m.
  • the satellites are smaller even with the thinnest nozzle plate, and are suppressed at 53 ⁇ m thickness and above.
  • thicker barriers have been found to demonstrate the same effect as thicker top plates.
  • thicker barriers present a drawback, namely, they increase the height of the refill inlet 23 . This causes the ink to refill too fast.
  • Present manufacturing techniques do not allow a decrease in the width of the refill inlet 23 sufficiently to compensate for this increased height.
  • the offset employed in the present invention is different than the offset disclosed and claimed in U.S. Patent 4,794,411, issued December 27, 1988, and assigned to the same assignee as the present application.
  • the offset in that patent ranges from 1 to 25 ⁇ m, and is to correct trajectory of the first drop of ink (in the single drop mode) or of the second and subsequent drops (in the multi-drop mode), particularly when the pen is operating at high frequencies (on the order of 50 kHz) and with up to 10 drops per firing burst. While that patent does not disclose the nature of the ink employed, all studies were performed with conventional aqueous dye-based ink systems.
  • the use of an increased distance between the resistor and the top of the nozzle plate is expected to find use in thermal ink-jet pens that employ an ink which includes a pigment-polymer system.
EP19940302813 1993-04-29 1994-04-20 Dispositif d'écriture thermique Expired - Lifetime EP0622198B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US5546693A 1993-04-29 1993-04-29
US55466 2002-01-22

Publications (3)

Publication Number Publication Date
EP0622198A2 true EP0622198A2 (fr) 1994-11-02
EP0622198A3 EP0622198A3 (fr) 1995-02-08
EP0622198B1 EP0622198B1 (fr) 1997-02-19

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EP19940302813 Expired - Lifetime EP0622198B1 (fr) 1993-04-29 1994-04-20 Dispositif d'écriture thermique

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EP (1) EP0622198B1 (fr)
JP (1) JPH071735A (fr)
DE (1) DE69401759T2 (fr)
HK (1) HK92297A (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0792744A2 (fr) * 1996-02-29 1997-09-03 Hewlett-Packard Company Orifice de tête d'impression asymétrique
US6145963A (en) * 1997-08-29 2000-11-14 Hewlett-Packard Company Reduced size printhead for an inkjet printer

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
IT201600083000A1 (it) * 2016-08-05 2018-02-05 St Microelectronics Srl Dispositivo microfluidico per la spruzzatura termica di un liquido contenente pigmenti e/o aromi con tendenza all'aggregazione o al deposito

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4794411A (en) * 1987-10-19 1988-12-27 Hewlett-Packard Company Thermal ink-jet head structure with orifice offset from resistor
EP0303350A1 (fr) * 1987-08-10 1989-02-15 Hewlett-Packard Company Formation de gouttelettes au moyen d'une tuyère déplacée
JPH02276648A (ja) * 1989-04-18 1990-11-13 Ricoh Co Ltd 液体噴射記録ヘッド
US4980703A (en) * 1987-04-30 1990-12-25 Nec Corporation Print head for ink-jet printing apparatus
EP0464733A2 (fr) * 1990-07-02 1992-01-08 Xerox Corporation Tête à jet d'encre thermique avec contrôle de la localisation de l'effondrement des bulles

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4980703A (en) * 1987-04-30 1990-12-25 Nec Corporation Print head for ink-jet printing apparatus
EP0303350A1 (fr) * 1987-08-10 1989-02-15 Hewlett-Packard Company Formation de gouttelettes au moyen d'une tuyère déplacée
US4794411A (en) * 1987-10-19 1988-12-27 Hewlett-Packard Company Thermal ink-jet head structure with orifice offset from resistor
JPH02276648A (ja) * 1989-04-18 1990-11-13 Ricoh Co Ltd 液体噴射記録ヘッド
EP0464733A2 (fr) * 1990-07-02 1992-01-08 Xerox Corporation Tête à jet d'encre thermique avec contrôle de la localisation de l'effondrement des bulles

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 15, no. 39 (M-1075) (4567) 30 January 1991 & JP-A-02 276 648 (RICOH CO., LTD.) 13 November 1990 *

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6527369B1 (en) 1995-10-25 2003-03-04 Hewlett-Packard Company Asymmetric printhead orifice
EP0792744A2 (fr) * 1996-02-29 1997-09-03 Hewlett-Packard Company Orifice de tête d'impression asymétrique
EP0792744A3 (fr) * 1996-02-29 1998-11-18 Hewlett-Packard Company Orifice de tête d'impression asymétrique
US6145963A (en) * 1997-08-29 2000-11-14 Hewlett-Packard Company Reduced size printhead for an inkjet printer
US6146915A (en) * 1997-08-29 2000-11-14 Hewlett-Packard Company Reduced size printhead for an inkjet printer

Also Published As

Publication number Publication date
DE69401759D1 (de) 1997-03-27
DE69401759T2 (de) 1997-10-09
EP0622198B1 (fr) 1997-02-19
JPH071735A (ja) 1995-01-06
HK92297A (en) 1997-08-01
EP0622198A3 (fr) 1995-02-08

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