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
  • B41J2/07—Ink jet characterised by jet control
  • B41J2/115—Ink jet characterised by jet control synchronising the droplet separation and charging time
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
  • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
  • B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
  • B41J2/01—Ink jet
  • B41J2/015—Ink jet characterised by the jet generation process
  • B41J2/02—Ink jet characterised by the jet generation process generating a continuous ink jet
  • B41J2/025—Ink jet characterised by the jet generation process generating a continuous ink jet by vibration
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
  • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
  • B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
  • B41J2/01—Ink jet
  • B41J2/015—Ink jet characterised by the jet generation process
  • B41J2/02—Ink jet characterised by the jet generation process generating a continuous ink jet
  • B41J2/03—Ink jet characterised by the jet generation process generating a continuous ink jet by pressure

Definitions

• This invention relates to the field of non- contact fluid marking devices which are commonly known as "ink jet” devices.
• Ink jet devices are shown generally in U.S. Patent No. 3,373,437, issued March 12, 1968, to Sweet & Cumming: No. 3,560,988, issued February 2, 1971 to Krick; No. 3,579,721, issued May 25, 1971 to Kaltenbach; and No. 3,596,275, to Sweet, issued July 27, 1971.
• jets very narrow streams are created by forcing a supply of recording fluid or ink from a manifold through a series of fine orifices or nozzles.
• the chamber which contains the ink or the orifices by which the jets are formed are vibrated or "stimulated” so that the jets break up into droplets of uniform size and regular spacing.
• Each stream of drops is formed in proximity to an associated selective charging electrode which establishes electrical charges on the drops as they are formed.
• the flight of the drops to a receiving substrate is controlled by interaction with an electrostatic deflection field through which the drops pass, which selectively deflects them in a trajectory toward the substrate, or to an ink collection and recirculation apparatus (commonly called a "gutter") which prevents them from contacting the substrate.
• an electrostatic deflection field through which the drops pass, which selectively deflects them in a trajectory toward the substrate, or to an ink collection and recirculation apparatus (commonly called a "gutter") which prevents them from contacting the substrate.
• the stream has a natural tendency, due at least in part to the surface tension of the fluid, to break up into a succession of droplets.
• the droplets are ordinarily not uniform as to dimension or frequency. In order to assure that the droplets will be substantially uniform in dimension and frequency.
• Sweet provides means for introducing what he refers to as "regularly spaced varicosities" in the stream. These varicosities create undulations in the crosssectional dimension of the jet stream issuing from the nozzle. They are made to occur at or near the natural frequency of formation of the droplets. As in Sweet, this frequency may be typically on the order of 120,000 cycles per second.
• Krick utilizes a supersonic vibrator in the piping through which ink is fed from the source to the apparatus; and in Kaltenbach, the ink is ejected through orifices formed in a perforated plate which is vibrated continuously at a resonant frequency.
• sweet approach non- contact marking devices utilizing fluid droplet streams have become commercially developed.
• ink jet devices that all of them utilize some type of varicosity inducing means or "stimulator" to induce regular vibrations into the stream to provide regularity and uniformity of the droplets.
• Stoneburner U.S. Patent No. 3,882,508, issued May 6, 1975 proper stimulation has been one of the most difficult problems in the operation of jet drop recorders. For high quality recording it has been necessary that all jets be stimulated at the same frequency and with very nearly the same power to cause break-up of all the streams into uniformly sized and regularly spaced drops. Furthermore, it is necessary that drop generation not be accompanied by generation of "satellite drops", and that the break-up of the streams into drops occur at a predetermined location in proximity to the charging electrode, both of which are dependent on the power of delivery at each jet. Stoneburner shows means for generating a traveling wave along the length of an ink supply manifold of which an orifice plate forms one side. The wave guide so formed is tapered or progressively decreased in width along its length, to counteract and reduce the natural tendency toward attenuation of the drop stimulating bending waves as they travel down, the length of the orifice plate.
• Satellite or very small droplets tend to form in between each of the larger droplets and cause diff iculties within the system in that these fine droplets tend to escape and be dispersed into the surrounding area or beyond the acceptable target area limits .
• Satellite droplet formation is a sensitive function of the properties of the ink or treating liquid being used so that the problem of stimulation is further complicated.
• the traveling waves generated by the external or art if icial perturbation means substantially limit the length of those devices.
• such known devices are limited to cross-machine or ifice plate lengths no greater than 10.5 inches (26.67 cm) where there are 120 jets to the inch and the artificial perturbation means is operating at 48 kilocycles .
• the poss ible length of the or ifice plates is reduced, while at lower frequencies the length might be lengthened.
• the pr imary disadvantage is encounte red in trying to build a perturbed or if ice system suitable for treatment of continuous length broad width goods , for example including those in the textile field, wallpaper , paper or other continuous length broad width goods or in continuously or intermittently fed forms of other wide substrates or mater ials , where any such goods , substrates or materials range in width from about one foot to about several yards .
• This "narrow random distribution" effect is utilized according to a preferred form of the invention in apparatus having: a source of treating liquid which is to be applied under higher pressure than is normally used for equivalent accuracy of droplet placement; a series of jet orifices of smaller diameter than usual, for equivalent droplet placement accuracy, through which orifices the treating liquid or coloring medium is forced as fine streams that break randomly into discrete droplets; electrode means for imparting electrostatic charges to the drops as they form; and deflection means for directing the paths of selected droplets in the streams toward a receiving substrate or toward a gutter or other collecting means.
• the charging electrode is more extensive than with a stimulated system since the break-off point may vary more in both space and time.
• an unperturbed system with the same flow rate requires a different orifice size and pressure than a perturbed system.
• the or ifice s ize must be smaller than would be used to achieve the same accuracy in a conventional perturbed system, typically no more than about 70% the or if ice diame ter of a perturbed system having the same accuracy of droplet placement or droplet misregistration value .
• the liquid head pressure is also or alternatively, substantially higher, preferably at least about four times that of a perturbed system w ith correspond ing accuracy . Further , it is des irable that the charging voltage be higher , by a factor of at least about 1.5 times .
• droplet misregistration value is defined as the offset distance or variation from a straight line, measured in a direction perpend icular to the direction of travel of the substrate , of a mark on the substra te when all jets in an array perpendicular to the direction of motion of the substrate are switched at the same time from being caugh t by the gutter to being delivered to the substrate .
• the perturbations that cause drop break-off in unstimulated jets generally arise from the environment in which the system is found. Generally these fluctuations are produced by the normal sound and acoustic motion that are inherently present in the fluid. However, in some "noisy" environments , unwanted external perturbations , for example , factory whistles , vibrations from gears and other machine movements , and even sound vibrations from human voices , can have an overpowering, influence and cause a change in the mean break-off point of the jets in an unstimulated system. In a mod ified embod iment of this invention, the system can be irregularly stimulated, as by a no ise source which generates random vibrations . I believe this embodiment can be found useful where the apparatus is to be used in a noisy area. In such an environment, the application of the irregular noise vibration will surprisingly produce more regular results from jet to jet than application of regular cyclical vibrations.
• FIGURE 1 is a diagrammatic cross-sectional illustration of a binary continuous fluid or liquid jet apparatus in accordance with the invention
• FIGURE 2 is a diagrammatic perspective illustration showing the droplet charging means and the droplet deflecting means
• FIGURE 3 is a schematic illustration of a modified embodiment of the invention wherein the apparatus is stimulated by a random noise generator that drives an acoustic horn; and
• FIGURE 4 is a diag rammatic illustration of another embodiment of a random noise perturbed system in accordance with the invention, where in a se ries of piezoelectr ic crystals apply random noise perturbations to a wall of the fluid or liquid supply manifold or chamber.
• the apparatus includes a supply or source of treating liquid 10 under pressure in a manifold or chamber that supplies an orifice plate 12 having a plurality of jet orifices 14.
• Streams or jets of liquid 16 forced through the or ifices 14 pass through electrostatic droplet charging means 18 , 18 , which select ively imparts to the liquid charges that are retained on the droplets as the streams break into discrete droplets.
• the charging plates 18, 18 must be sufficiently extensive in length and have a dimension wide enough in the direction of jet flow to charge droplets regardless of the random points at which their break-off occurs.
• the perturbations caused break-off to occur in a narrow zone, downstream of the or ifices .
• the point of break-off varies more widely.
• the ribbon like charging plates 18, 18 must provide a field that extends to the region of breakoff of such droplets.
• the ribbon like charging plates should preferably have a dimension of about 100d inches (100 d cm) in the direction of jet flow where d is the orifice diameter in inches or centimeters. Their width or dimension in the direction of droplet flow could range from a size greater than about 30d to less than about 300d. Charging voltages to charge plates 18,18 preferably range from about 50 to about 200 volts.
• the droplets in flight then pass a deflecting ribbon or means 20 which directs the paths of the charged droplets toward a suitable gutter or collector 22. Uncharged drops proceed toward a receiving substrate 24, which is supported by and may be conveyed in some predetermined manner by means not shown, relative to the apparatus, in the direction of arrow 26.
• the deflector ribbon or means 20 is preferably operated at voltages ranging from about 1000 to about 3000 volts.
• the structure of the present invention differs from the prior art in that the streams break up into droplets in response to a variety of factors including internal factors such as surface tension, internal acoustic motion, and thermal motion, rather than regular external perturbation. No regular varicosity inducing means are utilized, in contrast to what has heretofore been believed essential. Droplet formation takes place randomly.
• the mean droplet size is about .004" (.0102 cm).
• the normalized standard deviation of the droplet sizes (that is, the standard deviation of droplet size, divided by the mean droplet size) is about .1; that is, 68% of the droplets are within .0004" (.0010 cm) of the mean droplet size of .004"
• the fluid dynamic force from passage through air that tends to slow them down is proportional to the square of the ratio of their diameters so that larger drops tend to maintain faster speeds in traveling to the substrate. Assuming, however , that all jets break off at the same time, for an or ifice diameter of .003" ( .0076 cm) , a distance to the substrate of one inch, a jet velocity of 400 inches per second (1000 cm/second) and a deviation of .1 inch ( .254 cm) drop diameter, the misregistration on the substrate is less than two thousandths of an inch ( .0051 cm) .
• the resulting droplet (which I shall call the "late droplet") will have a farther distance to travel to the substrate than a droplet from the mean breakoff point (which I shall call the "mean droplet”) .
• the total spread of drop spacings I have noticed is about 6 or +3 and -3 about the mean.
• drop spacings can vary from this , for example, from about 2 to about 8 but will generally be greater than about 1.
• V is the jet velocity in inches per second (or cm/second) , d the or ifice diame ter in inches (or cm) , and V' the rate of movement of the substrate in inches per second (or cm/second) the arrival of the late droplet at the substrate will occur about n (4.51d/V) seconds after the arrival of the mean droplet. During this time interval the moving substrate will have traveled a distance of n (4.51d) V'/V inches (or cm).
• the misregistration error is .0061 inches (.0155 cm). It is to be noted that if d were times larger and V twice smaller, the error would be larger, or about .017 inches (.0432 cm).
• the use of the smaller diameter orifice and the higher pressure fluid in an unstimulated system can achieve smaller misregistration errors than a perturbed system of conventional orifice diameter and pressure.
• perturbation means have been required to narrow the distribution in drop size to essentially zero, to achieve acceptable misregistration error.
• I have found that errors due to the distribution of drop sizes can be substantially reduced by certain conditions. This can be seen from the following analysis.
• the normalized standard deviation of droplet size remains constant as the diameter of the orifice is made smaller and also as the pressure P is increased, in the absence of perturbing means. If the orifice diameter is reduced by, say, a factor of the square root of two the area of the orifice is accordingly decreased by a factor of two. If at the same time stream velocity is increased by a factor of two, the net flow from the orifice remains constant.
• the or if ice size may be in the range of .00035 to .020 inches ( .0008 to .05 cm) and the fluid or liquid pressure may be in the range of 2 to 500 psig (0.14 to 35 kg/cm 2 ) .
• the value of droplet misregistration error can be less than about 0.1 inch ( .254 cm) for applications on substrates having a relatively smooth surface while for application to substrates having relatively unsmooth, rough or fibrous surfaces the droplet misregistration error can be less than about 0.4 inches (1.016 cm), or even 0.9 inches (2.3 cm) where such misregistration could be acceptable, such as where the printing or image will only be viewed from a distance.
• liquid to treat a substrate require an orifice diameter of about 0.004 inches (.0102 cm) with the center to center spacing of orifices being about 0.016 inches (.0406 cm).
• the liquid-head pressures behind the orifices can vary from about 2 to about 30 psig (0.14 to 2.1 kg/cm 2 ). However, the preferred pressure range varies from about 3 to about 7 psig (0.2 to 0.5 kg/cm 2 ).
• the substrate can move at a velocity (V') of about 0 to about 480 inches per second (1300 cm/sec) with a preferred narrower range varying from about 5 to about 150 inches per second (12 to 380 cm/sec) and the most preferred rate being about 60 inches per second (152.4 cm/sec or 100 yards per minute).
• V' a velocity of about 0 to about 480 inches per second (1300 cm/sec) with a preferred narrower range varying from about 5 to about 150 inches per second (12 to 380 cm/sec) and the most preferred rate being about 60 inches per second (152.4 cm/sec or 100 yards per minute).
• More general ranges for the parameters involved, including the orifice and pressure ranges, are a jet velocity (V) ranging from about 200 to about 3200 inches per second (500 to 8200 cm/sec) with the more preferred velocity range varying from about 200 to about 500 inches per second (500 to 1300 cm/sec) for a general purpose liquid applicator and the most preferred jet velocity being about 400 inches per second (1000 cm/sec).
• V jet velocity
• substrates could be moved at rates faster than 480 inches per second (1300 cm/sec), such as speeds of 800-1000 inches per second (2000 to 2600 cm/sec), and this apparatus could have applicability to printing at such substrate feed rates.
• Fine printing, coloring, and/or imaging of substrates similar to the results obtainable from a perturbed system can be obtained with the present invention by using an orifice having a diameter of about 0.0013 inches (.0033 cm) with appropriate center to center spacing.
• the pressures will be greater than in the general application circumstances above and will range from about 15 to about 70 psig (1 to 5 kg/cm 2 ), with the preferred pressure being about 30 psig (2 kg/cm 2 ).
• jet velocities will preferably vary from about 600 to about 1000 inches per second (1500-2500 cm/sec) with the preferred velocity being about 800 inches per second (2000 cm/sec).
• the viscosities of the ink, colorant or treating liquid are limited only by the characteristics of the particular treating liquid or coloring medium relative to the orifice dimension. From a practical standpoint, the liquid or medium will generally have a viscosity less than about 100 cps and preferably about 1 to about 25 cps.
• the present invention can produce applicators of virtually almost any orifice plate length, as discussed previously, the range of application, unlike the previously discussed perturbed systems, is extremely broad. This is because the jet orifices can not only be constructed in very short lengths, such as a few centimeters or inches, they can also extend for any desired distance for example, .1 inch to 15 feet (.254 to 460 cm) or longer. Accordingly, the present invention is uniquely suitable for use with wide webs or where relatively large surfaces are to be colored or printed with indicia of some type. One example is printing. coloring or otherwise placing images on textiles but it should be clearly understood this is not the only application of this invention. In a similar manner the characteristics of the receiving substrate can vary markedly.
• Suitable textile dyes include reactive, vat, disperse, direct, acid, basic, alizarine, azoic, naphthol, pigment and sulphur dyes. Included among suitable colorants are inks, tints, vegetable dyes, lakes, mordants and mineral colors.
• treating liquids include any desired printing, coloring or image forming agents or mediums, including fixatives, dispersants, salts, reductants, oxidants, bleaches, resists, fluorescent brighteners and gums as well as any other known chemical finishing agents such as various resins and reactants and components thereof, in addition to numerous additives and modifing agents.
• Figures 1 and 2 The apparatus shown in Figures 1 and 2 is unperturbed. As previously mentioned, background or other vibrations in the area of use can themselves sometimes act as perturbation means and produce undesirable variable results.
• Figures 3 and 4 show a modified embodiment of the apparatus, wherein the system is not regularly perturbed, but is subject to irregular or noise perturbation, which overrides or masks such background vibration.
• the noise source includes an amplifier 30 which applies noise from a resistive or other electrical source 32, to a transducer such as an acoustic horn 34. The horn imparts the noise vibrations to the fluid or the manifold. These random perturbations may be applied to the fluid using prior art transducers; but the perturbation they apply herein is irregular, not regular.
• the noise transducer is a set of piezoelectric crystals 40 which are mounted to wall 42 of the fluid manifold 12.
• Other types of transducers may be used, as known in the art. The difference is that they are operated in a narrow band of random frequencies, not at regular frequencies.
• the central frequency of the noise approximate the natural frequency of droplet breakup. This is about V/4.51 d cycles per second where d is the jet diameter in inches or cm and V the velocity of the jet in inches per second.
• the band width is desirably less than about 12,000 cycles/ second, so that the random vibrations are most effective in achieving breakoff.

Landscapes

• Treatment Of Fiber Materials (AREA)
• Particle Formation And Scattering Control In Inkjet Printers (AREA)
• Ink Jet (AREA)
• Application Of Or Painting With Fluid Materials (AREA)
• Telephone Function (AREA)
• Manufacturing Of Micro-Capsules (AREA)
• Nozzles (AREA)
• Coating Apparatus (AREA)

Priority Applications (4)

Applications Claiming Priority (2)

Publications (1)

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Citations (4)

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• 1982
  • 1982-01-26 IE IE159/82A patent/IE53454B1/en unknown
  • 1982-01-29 IN IN68/DEL/82A patent/IN157640B/en unknown
  • 1982-02-01 NZ NZ199622A patent/NZ199622A/en unknown
  • 1982-02-02 CA CA000395424A patent/CA1191048A/en not_active Expired
  • 1982-02-03 ES ES509282A patent/ES509282A0/es active Granted
  • 1982-02-03 MX MX191249A patent/MX160194A/es unknown
  • 1982-02-03 PT PT74383A patent/PT74383B/pt unknown
  • 1982-02-03 AR AR288335A patent/AR229416A1/es active
  • 1982-02-03 WO PCT/US1982/000140 patent/WO1982002767A1/en active IP Right Grant
  • 1982-02-03 GB GB08227548A patent/GB2108433B/en not_active Expired
  • 1982-02-03 BR BR8205986A patent/BR8205986A/pt unknown
  • 1982-02-03 JP JP57500885A patent/JPS58500014A/ja active Pending
  • 1982-02-03 AU AU82035/82A patent/AU550059B2/en not_active Ceased
  • 1982-02-04 EP EP86104112A patent/EP0196074B1/en not_active Expired - Lifetime
  • 1982-02-04 AT AT86104112T patent/ATE57138T1/de not_active IP Right Cessation
  • 1982-02-04 DE DE8282100804T patent/DE3279204D1/de not_active Expired
  • 1982-02-04 KR KR8200470A patent/KR880001453B1/ko active
  • 1982-02-04 EP EP82100804A patent/EP0057472B1/en not_active Expired
  • 1982-02-04 AT AT82100804T patent/ATE38493T1/de active
  • 1982-02-04 ZA ZA82705A patent/ZA82705B/xx unknown
  • 1982-02-04 GR GR67210A patent/GR78350B/el unknown
  • 1982-02-04 DE DE8686104112T patent/DE3280256D1/de not_active Expired - Fee Related
  • 1982-09-24 FI FI823289A patent/FI75225C/fi not_active IP Right Cessation
  • 1982-10-01 DK DK437182A patent/DK437182A/da not_active Application Discontinuation
  • 1982-10-01 NO NO823317A patent/NO823317L/no unknown
• 1986
  • 1986-04-29 AU AU56818/86A patent/AU574573B2/en not_active Ceased
  • 1986-07-10 HK HK527/86A patent/HK52786A/xx unknown

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