FIELD OF THE INVENTION
[0001] This invention relates to the field of noncontact fluid marking devices which are
commonly known as "ink jet" devices.
THE PRIOR ART
[0002] 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.
In all of those devices, jets (very narrow streams) are created by forcing a supply
of recordinq 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.
[0003] While it has been known that a fine liquid jet will break into discrete droplets
under its inherent thermal and acoustic motion even in the absence of any external
perturbations, it has heretofore generally been believed that specifically calibrated
separate perturbation at or near the natural frequency of drop formation was a practical
necessity to produce droplets that are regularly spaced, sized, and timed across the
orifice array to permit proper use of the apparatus. Printing with charged drops requires
relatively precise control of the droplet paths to the ultimate positions on the receiving
substrate, and drop size, spacing, and charge level have generally been regarded as
critical factors. Thus, Sweet requires perturbation means for assuring that droplets
in the stream are spaced at regular intervals and are uniform in size.
[0004] As noted in Sweet, 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. However,
as is easily observed in a jet of water squirted through a garden hose nozzle, 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 cross-sectional 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.
[0005] A wide variety of varicosity inducing means are now known in the art. For example,
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.
[0006] Since the advent of the Sweet approach, noncontact marking devices utilizing fluid
droplet streams have become commercially developed. However, so far as is known to
me, it has been a characteristic of 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.
[0007] As noted in 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.
[0008] 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.
BRIEF DESCRIPTION OF THE PRESENT INVENTION
[0009] In practice, there is often an undesirable interaction between the stimulator and
the structure of the ink delivery system. This adverse effect may show up as a tendency
for the overall system to achieve non-uniform stimulation across the orifice array
due to reflected and interfering waves (as referred to in Stoneburner, just discussed),
such that certain orifices do not receive appropriate stimulation while others have
too much. The system thus has "cusps" or null points that are reflected as degradations
in the quality of droplet deposition. Furthermore, with these variations in power,
satellite or very small droplets tend to form in between each of the larger droplets
and cause difficulties 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.
[0010] Another and major limiting factor of the known perturbed ink jet systems resulting
from the stimulator is that the traveling waves generated by the external or artificial
perturbation means substantially limit the length of those devices. From a practical
standpoint, such known devices are limited to cross-machine orifice 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. At higher frequencies
the possible length of the orifice plates is reduced, while at lower frequencies the
length might be lengthened.
[0011] There are numerous disadvantages associated with such orifice plate limitations.
The primary disadvantage is encountered in trying to build a perturbed orifice 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 materials,
where any such goods, substrates or materials range in width from about one foot to
about several yards. Experience shows that it is extrememly difficult and, practically
speaking, almost impossible to combine two or more of the limited length perturbed
orifice plates across the needed distance in a manner that will permit the uniform
continuous treating of such goods or materials sufficiently to mask the separation
between the perturbed orifice plate sections, and/or to mask the effect of their mutually
different operational patterns. It becomes increasingly difficult to obtain a satisfactory
result as the number of such short length perturbed orifice plates is increased to
span increasing widths of goods to be treated.
[0012] With the present invention, however, where no artificial or external perturbation
is being used, there is virtually no limitation on the length of the orifice plate
or the extent over which such orifices can be made available for use across the width
of a wide or narrow substrate or receiving medium. Thus, textile paper or other substrates
having widths varying from a few feet to many yards can be treated as they are moved
or otherwise indexed beneath a single, machine-wide orifice structure. A plurality
of such machine-wide orifices can of course be operated in tandem or in some predetermined
manner or sequence to accomplish any desired result.
[0013] I have found that although droplet break-up in an unperturbed, continuous jet system
is a random process, the distribution of random droplet sizes and spacings is nevertheless
quite narrow. I have also found that at smaller orifice sizes and higher fluid pressures,
the variations among randomly generated droplets can be made sufficiently narrow so
that the resulting random droplet streams become useful, for example, in applying
color patterns or any type of treating agent or agents to textiles or for applying
indicia or treatments to a variety of other surfaces employing a variety of liquids.
[0014] 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. Further, the charging electrode is more extensive
than with a stimulated system since the break-off point may vary more in both space
and time.
[0015] Neither the apparatus nor the process has perturbation means that would impart regular
cyclical vibrations or cause the liquid being applied to break into droplets more
uniform than their unperturbed, random size distribution.
[0016] To achieve a given accuracy of droplet placement, or "droplet misregistration value,"
an unperturbed system with the same flow rate requires a different orifice size and
pressure than a perturbed system. The orifice size must be smaller than would be used
to achieve the same accuracy in a conventional perturbed system, typically no more
than about 70% the orifice diameter 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 with corresponding accuracy. Further, it is desirable that
the charging voltage be higher, by a factor of at least about 1.5 times.
[0017] For purposes of this specification and claims, the term "droplet misregistration
value" is defined as the offset distance or variation from a straight line, measured
in a direction perpendicular to the direction of travel of the substrate, of a mark
on the substrate when all jets in an array perpendicular to the direction of motion
of the substrate are switched at the same time from being caught by the gutter to
being delivered to the substrate.
[0018] 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 modified
embodiment of this invention, the system can be irregularly stimulated, as by a noise
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.
[0019] Other objects, features, and characteristics of the present invention as well as
the process, and operation and functions of the related elements and the combination
of parts, and the economies of manufacture, will become more apparent from the following
description and the appended claims with reference to the accompanying drawings, all
of which form a part of this specification, wherein like reference numerals designate
corresponding parts in the various figures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] In the accompanying drawings:
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 diagrammatic illustration of another embodiment of a random noise perturbed
system in accordance with the invention, wherein a series of piezoelectric crystals
apply random noise perturbations to a wall of the fluid or liquid supply manifold
or chamber.
DETAILED DESCRIPTION OF THE PREFERRED
EMBODIMENT OF THE PRESENT INVENTION
[0021] While this invention may be similar to previously known ink jet recording apparatus
in that similar results.can be achieved, the basic operating principle of the present
invention offers radically from such known ink jet recording systems.
[0022] As shown diagrammatically in Figure 1 and 2, 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 orifices 14 pass through electrostatic droplet charging means 18, 18,
which selectively imparts to the liquid charges that are retained on the droplets
as the streams break into discrete droplets.
[0023] 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. In prior art apparatus, the perturbations
caused break-off to occur in a narrow zone, downstream of the orifices. Here, without
regular or separate artificial or external perturbation, the point of break-off varies
more widely. In order to assure that all late-to-break-off droplets are charged, the
ribbon like charging plates 18, 18 must provide a field that extends to the region
of breakoff of such droplets. In practice, the ribbon like charging plates should
preferably have a dimension of about 100 d inches (100 d cm) in the direction of jet
flow, where d is the orifice diameter in inchesor 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.
[0024] After charging, 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.
[0025] Reference may be had to known ink jet devices for further details of structural elements
suitable for use in such apparatus.
[0026] In part, 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.
[0027] Lord Rayleigh explored the dynamics of fluid jets around the beginning of the 20th
century. He found that a fluid stream issuing under pressure from a jet orifice breaks
into individual droplets at droplet-to-droplet intervals that statistically average
2π r, where r is the radius of the orifice producing the jet. The droplet diameters
average about 2.11 d. However, these spacings and sizes are only averages. Actual
break-up is a random process; the actual droplet size and spacings vary. The actual
sizes and spacings follow normal distribution curves around the means defined by the
Rayleigh formulae and in experiments since Lord Rayleigh's work I have found that
the average spacing is now better represented by the expression 4.51d with 4.51 being
an observed or measured number. For example, in apparatus having an ink pressure P
of 12 psig and an orifice diameter of .002" 0,051cm), the mean droplet size is about
.004" (0,0102cm). e 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" (0,001cm). mean droplet size of .004"
(0,0102cm). Further, the break-off point varies from jet to jet by up to six drop
spacings. These variances are too wide for utility in many applications. When intending
to print a horizontal line across a substrate, all jets are commanded to print at
the same time by removing voltage from the charge plate at all jet positions. It can
be seen that if all jets break up into droplets at the same time and at the same distance
from the orifice plate, the system will simultaneously cause all jets to start issuing
uncharged drops and these drops will proceed to the paper in step.
[0028] For the normalized standard deviation of droplet size of approximately 0.1, as is
encountered in practice, this corresponds to about a 32% chance the droplet will be
larger or smaller by that amount and the spot size on the substrate will correspondingly
vary by that size. This produces variation in the apparent uniformity of a horizontal
line. This effect will be minor, however, in that for a deviation of .1 with a droplet
of .004" (0,0102cm) in diameter, the variation will only be .001" (0,0025cm).
[0029] In flight from the point of break-off, larger drops have more mass than smaller drops,
in proportion to the third power of the ratio of their diameters. 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 orifice diameter of .003" (0,0076cm), a distance to the substrate
of one inch, a jet velocity of 400 inches per second (1000cm/sec), and a deviation
of .1 inch A drop diameter, the misregistration on the substrate is less than two
thousandths of an inch (0,0051 cm).
[0030] In the event one jet breaks off closer to the orifice plate than the mean break-off
point of all jets by some number n of mean drop spacings (half the total spread) 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"). To date, the total spread of drop spacings I have noticed
is about 6 or +3 and -3 about the mean. However, drop spacings can vary from this,
for example, from about 2 to about 8 but will generally be greater than about 1
. If V is the jet velocity in inches per second(or cm/sec), d the orifice diameter
in inches(or cm), and V' the rate of movement of the substrate in inches per second
(or cm/sec) arrival of the late droplet at the substrate will occur about n (4.5ld/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). By way of
example, at a substrate speed of 60 inches per second (152,4cm/sec) (corresponding
to a substrate moving at 100 yards per minute), a jet velocity of 8
00 inches per second (2032cm/sec), an orifice diameter of .003 inches (0,0076cm), and
with n = 6, the misregistration error is .
0061 inches (0,0155cm). It is to be noted that if d were
times larger and V twice smaller, the error would be 2
larger, or about .017 inches (0,0432cm). Thus, 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.
[0031] In devices heretofore available, perturbation means have been required to narrow
the distribution in drop size to essentially zero, to achieve acceptable misregistration
error. However, 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 (J2), 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.
[0032] For similar charge and deflection fields the drop trajectories remain constant, but
the natural frequency now is 2√2 higher and there are now 2√2 as many drops formed
per unit time, and the time of flight to the substrate is halved. If the breakup point
with a full sized jet varied six drop spaces due to the random nature of break-up,
as is often the case, a print error would occur of six times the break-off time interval
times the speed of the substrate. With the smaller, higher pressure jet, the same
error in break-off distance would result in an error only 1/2√2 as great, that is,
2.12 instead of six or only 35% of the error above. Furthermore, fluctuations in density
would now be averaged over 2√2 drops; if there is a 32% chance that the drop radius
for the larger orifice case varied 10%, with a corresponding volume variation of 33%,
there would only be a 9% chance the smaller orifice system would so vary.
[0033] Though a stimulated system can in principle be designed to deliver with high accuracy,
in practice errors occur of up to two drop spacings. With an unstimulated system,
the break-off point can vary over six to seven drop spacings, but by reducing orifice
size and increasing pressure, this error can be reduced to that of a stimulated system
with the larger orifice size, while still offering the advantage of substantially
unlimited orifice plate length.
[0034] In general for this purpose, the orifice size may be in the range of .00035 to .020
inches (0,008 to 0,05cm); 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 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 (1,016cm), or even 0.9 inches (23cm) where
such misregistration could be acceptable, such as where the printing or image will
only be viewed from a distance.
[0035] More specifically I have found that general applications of a liquid to treat a substrate
require an orifice diameter of about 0.004 inches (0,0102cm), with the center to center
spacing of orifices being about 0.016 inches (0,0406cm). 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 (1300cm) per second with a preferred narrower range varying from
about 5 to about 150 inches (12 to 380 cm) per second and the most referred rate being
about 60 inches per second 152,4cm or 100 yards per minute).
[0036] 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 secoria
(500 to 8200 cm) with the more preferred velocity range varying from about 200 to
about 500 inches per second (500 to 1300 cm) for a general purpose liquid applicator
and the most preferred jet velocity being about 400 inches per second (1000cm). Also,
in certain instances substrates could be moved at rates faster than 480 inches per
second (1300cm), such as speeds of 800-1000 inches (2000 to 2600 cm) per second, and
this apparatus could have applicability to printing at such substrate feed rates.
[0037] 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 (0,0038cm) 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 (2kg/cm
2). Here, jet velocities will preferably vary from about 600 to about 1000 inches per
second (1500 to 2500 cm) with the preferred velocity being about 800 inches per second
(2000 cm).
[0038] 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.
[0039] Since 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,0,1" to 15 feet
ror 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.
[0040] In textile applications all textile dyes and dyestuffs and colorants can be_used,
being either natural or synthetic, so long as they are compatible with the material
from which the orifice plate is constructed, such as stainless steel or other chemically
resistant materials or combinations thereof, and are compatible as well with the orifice
dimensions which are desired to be used. (Large particle materials can cause unwanted
clogging.) Suitable textile dyes include reactive, vat, disperse, direct, acid, basic,
alizarine, azoic, naphtol, pigment and sulphur dyes. Included among suitable colorants
are inks, tints, vegetable dyes, lakes, mordants and mineral colors.
[0041] Included among the types of treating liquids are any desired printing, coloring or
image forming agents or mediums, including fixatives, dispersants, salts, reductants,
oxidants, bleaches, resists, fluonscent 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. It is believed that
all such materials could be effectively employed according to the present invention
to produce desired effects on a variety of substrates, as for example, all types of
paper and paper like products, cloth and textile webs of various woven, knitted, needled,
tufted, felted, batt, spun-, bonded and other non-woven types, metal sheet, plastics,
glass, gypsum and similar composition board, various laminates including plywood,
veneers, chipboard, various fiber and resin composites like Masonite, or any other
material as well as on a variety of surfaces including flat, curved, smooth, roughened,
or various other forms.
[0042] 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.
[0043] In Figure 3 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.
[0044] In Figure 4, 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.
[0045] It is desirable that 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.
[0046] While the invention has been described in connection with what is presently considered
to be the most practical and preferred embodiments, it is to be understood that the
invention is not to be limited to the disclosed embodiments but on the contrary, is
intended to cover various modifications and equivalent arrangements included within
the spirit and scope of the appended claims, which scope is to be accorded the broadest
interpretation so as to encompass all such modifications and equivalent structures.
1. A liquid jet device for printing, coloring or otherwise treating a receiving substrate
placed thereunder comprising means for randomly generating droplets frim a liquid
stream, said random generating means having an unlimited cross machine width and being
comprised of means defining a source of pressurized liquid and orifice means defining
a plurality of jet orifices having a diameter d through which said liquid issues so
that droplets are randomly formed having differing sizes and spacings therebetween,
said pressure and orifice dimensions being controlled so that droplet break up occurs
substantially within a predetermined distribution around a mean droplet size,
electrode means for selectively imparting charges to droplets,
collection means for collecting droplets; and deflection means for deflecting the
paths of predetermined droplets away from the receiving substrate to said collection
means.
2. A liquid jet device for applying the liquid to a substrate placed thereunder with
a droplet misregistration value less than about 0.9 inch comprising means for randomly
generating droplets from a liquid stream, said random generating means including means
defining a source of pressurized liquid and orifice means defining a plurality of
jet orifices having a diameter d through which said liquid issues so that droplets
are randomly formed having differing sizes and spacings therebetween, said pressure
and orifice dimensions being controlled so that droplet break up occurs substantially
within a predetermined distribution around a mean droplet size,
electrode means for selectively imparting charges to droplets,
collection means for collecting droplets; and deflection means for deflecting the
paths of predetermined droplets away from the receiving substrate to said collection
means.
3. A liquid jet device as in claim 1 or 2 wherein said device applies droplets on
the substrate at a droplet misregistration value less than about 0.1 inch.
4. A liquid jet device as in any one of claims 1, 2 or 3 wherein said droplet misregistration
value is defined by the expression n (4.51d)V'/V where n equals the number of mean
drop spacings a droplet is formed away from the mean breakoff point, d equals the
orifice diameter, V equals jet velocity and V' equals the rate of substrate movement.
5. A liquid jet device as in claim 4 wherein d ranges from about 0.00035 inches to
about 0.020 inches, n is greater than about 1, V ranges from about 200 to about 3200
inches per second and V' ranges from about 0 to about 480 inches per second.
6. A liquid jet as in claim 5 wherein the pressure ranges from about 2 psig to about
500 psig.
7. A liquid jet device as in claim 5 wherein said orifice is about .004 inches, the
pressure ranges from about 2 to about 30 psig. and the jet velocity is about 400 inches
per second.
8. A liquid jet device as in claim 5 wherein said orifice is about .0013 inches, the
pressure ranges from about 15 to about 70 psig and the jet velocity is about 800 inches
per second.
9. A liquid jet device as in any one of claims 1, 2, 4 or 5, wherein said electrode
means has a length parallel to droplet flow which ranges from about 30 to about 300
times the orifice diameter.
10. A liquid jet device as in claim 9 wherein the preferred length of said electrode
means is equal to about 100d.
11. A liquid jet device as in claim 9 or 10 wherein the charging voltage applied to
said electrode means ranges from about 50 to about 200 volts.
12. A liquid jet device as in any one of claims 1, 2, 4 or 5, wherein the,viscosity
of the liquid is less than about 100 cps.
13. A liquid jet device as in any one of claims 1, 2, 4 or 5 wherein said substrate
is moved with respect to said orifices at a rate less than about 480 inches per second.
14. A liquid jet device as in any one of claims 1, 2, 4, 5, 9 or 10 wherein said device
is operated at a charging electrode voltage which is at least 1.5 times that of a
regularly perturbed apparatus having the same droplet misregistration value.
15. A liquid jet device as in any one of claims 1, 2, 4 or 5 wherein said random generating
means operates in the absence of an artificial or external perturbation means for
imparting regular cyclical vibrations to said liquid to induce uniform droplet breakup.
16. A liquid jet device as in any one of claims 1, 2, 4, 5, 7, 8 or 10 wherein said
substrate is a textile.
17. A liquid jet device as in claim 16 wherein said liquid is natural or synthetic
textile dyes or colorants or mixtures thereof.
18. A liquid jet device as in any one of claims 1, 2, 4, 5, 7, 8 or 9 further including,
a random noise generator which applies irregular, randomly varying vibrations to said
liquid, to induce said streams to break up more randomly than in the absence of such
irregular vibrations.
19. A liquid jet device as in claim 18 wherein said random noise generator imparts
noise of a random frequency having a band width less than about 12,000 cycles per
second, to said ink.
20. A liquid jet device as in claim 18 wherein said random noise generator has a central
frequency which approximates the natural jet breakoff frequency of said streams.
21. A colored and/or imaged substrate having a width varying from less than about
0,1 inch to about 15 feet formed from randomly generated and precisely controlled
droplets of a treating liquid, whereby the droplets have been randomly formed from
a liquid stream in the absence of artificial or external vibration means so that the
droplets have differing sizes and spacings therebetween within a predetermined distribution
around a mean droplet size.
22. The substrate as in claim 21 wherein the substrate is a textile product and the
treating liquid is a natural or synthetic textile dyes or colorants or mixtures thereof.
23. A process for imprinting indicia on or coloring a substrate with a liquid comprising
the steps of:
establishing a liquid flow in the form of at least one jet stream by pressurizing
a source of liquid and forcing the liquid through at least one oriface and randomly
forming that stream into droplets by controlling the pressure and orifice dimensions
so that the random droplet breakup occurs substantially within a predetermined distribution
pattern around a mean droplet size,
selectively imparting charges to predetermined ones of said droplets,
deflecting the path of the charged droplets and collecting the thus deflected droplets,
whereby the uncharged droplets are allowed to be deposited on the substrate.
24. A process as in claim 23, wherein the orifice and pressure on the liquid jet are
established according to the droplet misregistration equation of n (4.51d) V'/V where
n equals the number of mean drop spacings a droplet is formed away from the mean breakoff
point, d equals the orifice diameter, V equals jet velocity and V equals the rate
of substrate movement so that drops reaching the substrate have a droplet misregistration
value less than about 0.9 inch.
25. A process as in claim 23 or 24 wherein the substrate is indexed in a predetermined
manner beneath said droplets.
26. A process as in claim 25 wherein said substrate is moved at a rate less than about
480 inches per second.
27. A process as in claim 23 or 24 wherein the pressure ranges from about 2 psig to
about 500 psig.
28. A process as in claim 23 or 24 wherein droplets are applied to the substrate at
a droplet misregistration value of less than about 0.1 inches.
29. A process as in any one of claims 23, 24 or 28 wherein the viscosity of the liquid
is less than about 100 cps.
30. A process as in any one of claims 23, 24 or 28 including the additional step of
generating irregular and randomly varying vibrations and applying such vibrations
to the liquid to induce the liquid streams to break up more randomly than in the absence
of such irregular vibrations.
31. A process as in claim 30 wherein said randomly generated vibrations are generated
at a random frequency having a band width less than about 12,000 cycles per second.
32. A process as in any one of claims 23, 24 or 28 wherein the substrate is a textile
and the liquid is natural or synthetic textile dyes or colorants or mixtures thereof.