U.S. patent number 3,852,772 [Application Number 05/177,587] was granted by the patent office on 1974-12-03 for mechanically cycled ink jet printer.
This patent grant is currently assigned to Recognition Equipment, Incorporated. Invention is credited to Hubert D. Faulkner, Richard M. Hecht.
United States Patent |
3,852,772 |
Hecht , et al. |
December 3, 1974 |
MECHANICALLY CYCLED INK JET PRINTER
Abstract
A mechanically cycled ink jet printer nozzle, through which a
stream of ink passes and from which there issues a stream of
droplets of ink, is laterally vibrated to cause the stream of
droplets to follow a cyclic trajectory or pattern such as a sine
wave. Droplets in portions of the pattern then are selected to
remain uncharged and impinge a document to print thereon. For
nonselected portions, the droplets are charged and deflected to a
catcher to avoid printing.
Inventors: |
Hecht; Richard M. (Dallas,
TX), Faulkner; Hubert D. (Dallas, TX) |
Assignee: |
Recognition Equipment,
Incorporated (Irving, TX)
|
Family
ID: |
22649181 |
Appl.
No.: |
05/177,587 |
Filed: |
September 3, 1971 |
Current U.S.
Class: |
347/39; 347/107;
347/74 |
Current CPC
Class: |
B41J
2/105 (20130101) |
Current International
Class: |
B41J
2/105 (20060101); B41J 2/07 (20060101); G01d
015/18 () |
Field of
Search: |
;346/1,75 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Hertz et al.; A Method For the Intensity Modulation of a Recording
INR Jet and Its Applications; Acta Univ. Lond; Sec. 2, No. 15 pp.
1-16, 1967..
|
Primary Examiner: Hartary; Joseph W.
Attorney, Agent or Firm: Richards, Harris & Medlock
Claims
What I claim is:
1. An ink jet printer for printing a line of data on a document
during relative movement between the printer and the document which
comprises:
a. a nozzle structure for projecting a stream of ink droplets
toward the document, said nozzle structure includes a metal
mounting bar,
b. means for mechanically moving the nozzle cyclically in a
direction lateral to the axis of the nozzle to cyclically alter the
direction of travel of successive droplets and produce a droplet
pattern, said moving means includes a pair of field coils located
on opposite sides of said mounting bar, and means for cyclically
energizing said coils to repeatedly deflect said mounting bar
between said coils,
c. means for selectively charging the droplets issuing from the
nozzle to a potential above a predetermined level,
d. means for establishing a deflecting field in a region through
which the droplets pass,
e. an ink catcher adjacent to the path of said droplets, and
f. control means synchronized with the movement of the nozzle for
selectively energizing said charging means to charge the droplets
in those portions of the droplet pattern not desired on the
document whereby the reaction of the charged droplets with said
field directs said charged droplets into said catcher.
2. An ink jet printer for printing a line of data on a document
during relative movement between the printer and the document which
comprises:
a. a nozzle structure for projecting a stream of ink droplets
toward the document, said nozzle structure includes a metal
mounting bar;
b. means for mechanically moving the nozzle cyclically at a
constant frequency and amplitude in a direction lateral to the axis
of the nozzle to cyclically alter the direction of travel of
successive droplets and produce a droplet pattern, said moving
means includes:
a pair of field coils located on opposite sides of said mounting
bar; and
means for cyclically energizing said coils to repeatedly deflect
said mounting bar between said coils;
c. means for selectively charging the droplets issuing from the
nozzle to a potential above a predetermined level;
d. means for establishing an electric field in a region through
which the droplets pass; and
e. control means synchronized with the movement of the nozzle for
selectively energizing said charging means to charge the droplets
in those portions of the droplet pattern not desired on the
document whereby the reaction of the charged droplets with said
field prevents said charged droplets from reaching said
document.
3. An ink jet printer for printing a line of data on a document
during relative movement between the printer and the document which
comprises:
a. a nozzle structure for projecting a stream of ink droplets
toward the document,
b. means for mechanically moving the nozzle cyclically in a
direction lateral to the axis of the nozzle to cyclically alter the
direction of travel of successive droplets and produce a droplet
pattern, said moving means includes a serrated plate mounted for
movement in a direction transverse to the axis of said nozzle
whereby contact of the serrations with said nozzle induce cyclic
vibrations in said nozzle,
c. means for selectively charging the droplets issuing from the
nozzle to a potential above a predetermined level,
d. means for establishing a deflecting field in a region through
which the droplets pass,
e. an ink catcher adjacent to the path of said droplets, and
f. control means synchronized with the movement of the nozzle for
selectively energizing said charging means to charge the droplets
in those portions of the droplet pattern not desired on the
document whereby the reaction of the charged droplets with said
field directs said charged droplets into said catcher.
4. An ink jet printer for printing a line of data on a document
during relative movement between the printer and the document which
comprises:
a. a nozzle structure for projecting a stream of ink droplets
toward the document;
b. means for mechanically moving the nozzle cyclically at a
constant frequency and amplitude in a direction lateral to the axis
of the nozzle to cyclically alter the direction of travel of
successive droplets and produce a droplet pattern, said moving
means includes a serrated plate mounted for movement in a direction
transverse to the axis of said nozzle whereby said contact of the
serrations with said nozzle induce cyclic vibrations in said
nozzle;
c. means for selectively charging the droplets issuing from the
nozzle to a potential above a predetermined level;
d. means for establishing an electric field in a region through
which the droplets pass; and
e. control means synchronized with the movement of the nozzle for
selectively energizing said charging means to charge the droplets
in those portions of the droplet pattern not desired on the
document whereby the reaction of the charged droplets with said
field prevents said charged droplets from reaching said document.
Description
This invention relates to a mechanically cycled ink jet printer
nozzle cooperating with means for selectively charging droplets
issuing therefrom during selected portions of the mechanical cycle
for control of the trajectory of the droplets to permit some to
impinge a document and others to be intercepted before
impingement.
Ink jet printers heretofore have involved the projection of charged
droplets and the deflection of the droplets in an electrostatic
field by programming the magnitude of charge on the droplets. Thus,
control of charging systems has been complex. It has been found,
however, that the same results can be obtained by mechanically
cycling the nozzle from which the droplets immerge so that the
trajectory of the droplets is cyclically altered. If then the
droplet charging field is turned on and off during selective
portions of each cycle of the nozzle trajectory, the charged
droplets may be subject to a deflecting field which will direct the
charged droplets to a catcher and permit only noncharged droplets
to impinge a document.
The printing operation may be carried out by the simple switching
on and off of the droplet charging field between zero and a
predetermined gating level. Eliminated are the program requirements
for control of the charging voltage. Such systems greatly simplify
the control system while permitting printing of bar codes as well
as alphanumeric characters.
In accordance with the preferred embodiment of the invention, an
ink jet printer is provided for printing a line of data on a
document during relative movement between the printer and the
document. The nozzle structure is actuated to project a stream of
ink droplets toward the document. Means are provided for
mechanically cycling the nozzle laterally or perpendicularly to the
axis of the nozzle cyclically to alter the direction of travel of
successive droplets. Means are provided for selectively charging
the drops issuing from the nozzle to a potential above a
predetermined level. Means are also provided to establish an
electrostatic field in the zone through which the droplets pass.
Means synchronized with the vibration of the nozzle selectively
energizes the charging means to charge droplets in those portions
of the pattern not desired on the document.
For a more complete understanding of the present invention and for
further objects and advantages thereof, reference may now be had to
the following description taken in conjunction with the
accompanying drawings in which:
FIG. 1 is a side view of one embodiment of the writing portion of a
printer embodying the present invention;
FIG. 2 is a top view of the unit of FIG. 1;
FIG. 3 is a circuit diagram of the control system for the printer
of FIG. 1;
FIG. 4 is a diagram representing a sine wave pattern produced by
vibration of the nozzle support of FIG. 1;
FIG. 5 is a diagram illustrating coding of the circuit of FIG. 2
for selecting the portions of the pattern to be printed;
FIG. 6 illustrates a mode of imparting mechanical vibrations to the
nozzle by contact with a serrated surface;
FIG. 7 illustrates a further modification for vibrating the nozzle
through a torsion member;
FIG. 8 illustrates the system mounted for translation of the
printer relative to a fixed document;
FIG. 9 illustrates a further modification for translation of the
printer relative to a fixed document; and
FIG. 10 illustrates printing alphanumeric characters in accordance
with the present invention.
Referring now to FIGS. 1 and 2, an ink jet printer is illustrated
wherein a center supported bar 10 has a nozzle 11 secured to the
end of a tube 12 through which ink is supplied to nozzle 11. The
tube 12 is secured by a clamp 13 to one side of bar 10 and leads to
a pressurized ink supply (not shown) but connected to the end
14.
The bar 10 is mounted as to be mechanically driven for vibration in
the direction of the arrow 15 by piezoelectric crystal 16.
Longitudinal motion of the bar 10 in response to energization of
the crystal 16 breaks the stream of ink 17 which issues from the
nozzle 11 into discrete uniform droplets.
Support members 18 provide a mounting for bar 10 such that bar 10
is supported at a vibration node.
The mounting of bar 10 and the supply of ink therefor generally
will be as found in systems described in "Instruction Manual Ink
Jet Printer", (1970) by Recognition Equipment Incorporated, Dallas,
Tex.
In accordance with the present invention, the bar 10 is
mechanically cycled to produce vibration in a second mode in order
to cause the stream of ink droplets to trace a cyclic trajectory 20
such as a sine wave. More particularly, as illustrated in FIG. 1,
coils 21a and 21b are mounted on opposite sides of the bar 10. The
ends of magnetic core 23 for coils 21a and 21b face the surface of
the bar 10 at a location spaced from the nodal mounting.
In accordance with one embodiment of the invention, coils 21a and
21b were energized at a frequency of 600 cycles per second. In
contrast, the crystals 16 were energized at 48,000 cycles per
second.
As shown in FIG. 1 the stream of ink droplets issuing from nozzle
11 pass through a fork shaped pair of charging plates 24 and 25.
Charging plates are electrically common and are connected in a
circuit, later to be described, such that they will be either at
zero potential or at a significant potential above ground. The ink
supply and the ink in the stream of ink droplets initially are
always at ground potential.
A pair of deflecting plates 26 and 27 are maintained at a
predetermined constant potential.
An ink catcher 29 is mounted in front of a document 28 adjacent but
out of the normal path of the sinusoidal stream 20.
In accordance with the present invention the charging plates 24 and
25 are selectively connected to a potential source to establish
successive electrostatic fields. As the droplets pass through such
field, they will be given an electric charge. They are charged only
during those portions of the sine wave that are not to appear on
the document 28. When the droplets are charged to a predetermined
potential, the median 20a of the stream 20 is displaced to location
20b so that all charged droplets are caught by the catcher 29 and
directed to an excess ink reservoir.
By imparting mechanical motion to produce a cyclic pattern in the
trajectory of the droplets such as the sine wave illustrated in
FIG. 1, a greatly simplified writing system is provided. This is in
contrast with prior systems where the voltage on the charging
plates 24 and 25 had to be programmed to different levels for each
of the successive drops permitted to impinge the document. The
present invention permits merely switching on a constant voltage to
the charging plates 24 and 25 so that all unwanted portions of the
cyclic trajectory are directed to the catcher 29.
The invention thus far described is particularly useful in applying
bar codes to a document 28. It will be understood from the
following description of the control circuit that different modes
of bar coding may be accommodated. For example, some systems now in
operation require a binary bar code to consist of long bars
representing a one and half-length or short bars to represent
zeros. In other systems the presence of a bar indicates a one and
the absence of a bar indicates zero. Either type coding may be
accommodated. Further, it will be shown that this type of system
may be employed for writing alphanumeric characters with the
present simplified control system.
Uniform charging of droplets is preferably accomplished in
accordance with the phase adjusting method described and claimed in
U.S. Pat. No. 3,596,276 entitled "Ink Jet Printer With Droplet
Phase Control Means", filed by Kenneth T. Lovelady and Robert B.
McJohnson and assigned to the same assignee as this
application.
Referring now to FIG. 3, a control system has been shown wherein
the printer of FIGS. 1 and 2 is controlled to apply bar codes to a
document 28 as it moves past printer bar 10. Velocities of the
document may be on the order of 30 inches per second. The printer
is so controlled in this embodiment to accommodate an address
optically read from a letter such as document 28, analyzed and
converted to a suitable code by optical character recognition (OCR)
equipment (not shown). The code is then translated in the control
circuit of FIG. 3 to print a bar code representation of the address
in response to operation of the system shown in FIG. 3.
In FIG. 3, primary timing control is by way of a clock 30. The
clock 30 operates in this embodiment at 4,800 cycles per second.
The output line 31 leads to a pair of binary counters 32 and 33.
The counters 32 and 33 serve to divide the input signal on line 31
so that on each one of the output lines pulses are produced at
different fractional values of the input frequency. For example,
the signal on lead D of counters 32 and 33 is equal to 1/16 of the
input frequency, 300 pulses per second.
The outputs of the counters 32 and 33 are selectively connected by
way of NAND gates 34 and 35 to a NAND gate 36. The output of NAND
gate 36 is connected by way of NAND gate 37 and inverter 38 to a
high voltage amplifier 39. The output of amplifier 39 is then
applied to the charging plates 24 and 25, FIGS. 1 and 2. This
voltage is gated off and on to control the portions of the droplet
trajectory which impinge document 28 and the portions to be
directed to the catcher 29. It will be noted from FIG. 2 that a
light emitting diode 50 is positioned on one side of document 28
along the path of travel thereof. A light sensor transistor 51 is
positioned on the side opposite diode 50. The collector of sensor
50 is connected to a voltage comparator 52 whose output is applied
by way of an amplifier-inverter 53 to control a shift register 54.
The comparator 52 provides a 0-1 output depending on whether or not
a document is present between source 50 and sensor 51.
Selected outputs from the shift register 54 are connected by way of
a NAND gate 55 to a NAND gate 56 and thence to a second input of
NAND gate 37. By this means, amplifier 39 may be energized only
when a document is present in the field of the printer and then
only at a selected location on the document. More particularly, the
shift register 54 permits introduction of a selected delay in its
output. This delay compensates for the space between the location
of the document sensor units 50 and 51 and the actual location
along the path of travel of the document of bar 10. An additional
delay will be introduced to accommodate any desired margin on the
document before the printing of bar codes is to occur.
As illustrated in FIG. 3, the first and last outputs of the shift
register are connected to a NAND gate 55 to set the delay. Any
desired delay can be set by selecting outputs from a shift register
system for application of an enable pulse to the NAND gate 37.
Thus, in the system thus far described, the amplifier 39 is
conditioned to be turned on to apply a charging voltage to the
charging plates 24 and 25 to print a selected fraction of a wave
that would be traced by the stream of droplets were none of the
droplets charged. All droplets in the wave except the selected
fraction are charged. More particularly, referring to FIG. 4, a
sine wave 60 representing the trajectory of stream 20 is divided
into eight time segments. In accordance with the invention, long
bars are printed on a document by charging all of the cycle except
the fourth and fifth segments. A short bar is formed by charging
all of the droplets forming the sinusoidal waveform except those in
the fifth segment.
In accordance with the invention, the time occurrence of each of
the eight segments of the waveform is represented by a code at the
outputs of counters 32 and 33. The states of the counter outputs B,
C and D for each of the segments are illustrated in FIG. 4. At a
time corresponding with the first segment of the waveform, the
counter outputs are all zero. For the second segment, the states of
counter output lines B, C and D are B=1, C=0, and D=0. Lines B, C
and D are selected and employed as will now be explained. Because
of a 90.degree. phase shift involved between the excitation of the
coils 21a-21b and the motion of the bar 10, the mechanical waveform
is delayed 90.degree. from the electrical waveform to the time
position of waveform 61. Thus, with respect to the outputs B, C and
D of counter 32 during the intervals corresponding with the fourth
segment of waveform 61, the states are B=1, C=0, and D=1 and for
the fifth segment B=0, C=1, and D=1.
Lines B, C and D are connected to gate 34. Data input line X is
also connected to gate 34. Line X leads from an optical character
reader which reads data from document 28 and translates the same
into a sequence of 0 and 1 states on line X which represents the
bar code sequence to be printed. If a long bar is to be printed,
line X will be true as will lines B, C and D. This will result in
plates 24 and 25 being turned on during the fourth segment of
waveform 61.
Lines B, C and D are connected to gate 35. They will all be true
during the fifth segment so that a short bar segment will be
printed on each cycle.
FIGS. 2 and 3 also illustrate the drive system for the bar 10. It
will be noted that two coils 22a and 22b are connected to the input
of a full wave rectifying amplifier 100 to produce a D.C. voltage
at terminal 101 which is proportional in amplitude to the amplitude
of lateral vibration of the bar 10. This signal is then applied by
way of a scale and offset circuit 102 as an AGC signal to a
differential amplifier 103. The amplifier 103 is pulsed by a 300
cycle clock pulse applied from line D from counter 32 to one input
of the amplifier 103 and by way of inverter 105 to the other input
of the amplifier 103.
The output of amplifier 103 then energizes a driver circuit 106 for
coils 21a-21b. The driver circuit 106 is operated in a semi
push-pull mode. The waveform of the voltage at the output of the
amplifier 103 is almost a square wave. The waveform at the output
of driver circuit 106 is applied to the coils 21a-21b and is
illustrated by the graph associated with the output lines 107 and
108. By this means the bar 10 is dimensioned and driven at 300
cycles which is at or close to its resonant frequency. Thus, the
frequency is fixed and the phase relation with respect to the
signals from the binary counters 32 and 33 is known.
In practice, the connections between counter 32 and the amplifier
39 may be selected by trial and error. That is, a selection may be
made until the voltage is removed from the charging plates 24-25
during the substantially linear portion of the trajectory of the
waveform of FIG. 4 as represented by the fourth and fifth segments
thereof. In the example given, lines B, C and D were chosen because
the states thereon conveniently relate to and provide for selection
or designation of segments 4 and 5 of waveform 61.
In systems having different physical constants, different counter
outputs may be found necessary to provide for selection of the
desired segments.
Counter 33 in this embodiment is used only to provide an input to
shift register 54. Each cycle is divided into sixteenth segments
for more precise selection of the portion to be printed. Indeed,
for alphanumeric printing, finer division than sixteenths may be
necessary. In any event, the control may be as shown in FIG. 3. For
printing a 5 .times. 7 alphanumeric matrix, for example, the linear
portion of the trajectory (segments 4 and 5 of waveform 61) would
be divided into seven subdivisions. In such case, there would be
seven gates rather than the two gates 34 and 35.
Referring now to FIG. 5, a sine wave has been illustrated in dotted
lines with the bar portions which are selectively printed on the
document shown solid. The frequency of the drive signals applied to
the bar 10 and the speed at which document 28 travels are
coordinated such that the bars will occur at a desired spacing. The
amplitude of vibration and the distance from the document thus
determine the amplitude of the trajectory as selected to give the
desired bar heights.
By way of example and not by way of limitation, the embodiment of
the control circuit shown in FIG. 3 employed the following
components:
amplifier 39 Recognition Equipment Incorporated Standard Part No.
6053290 inverter 38 Motorola MC836 NAND gate 37 Motorola MC846 NAND
gate 36 Motorola MC846 NAND gate 35 Texas Instruments SN7420 NAND
gate 34 Texas Instruments SN7420 NAND gate 56 Motorola MC846 NAND
gate 55 Motorola MC846 comparator 52 National Semiconductor DM8820
amplifier- inverter 53 National Semiconductor DM8820 diode 50 Texas
Instruments X617 sensor 51 Texas Instruments L612 counters 32-33
Signetics N8281 shift register 54 Texas Instruments SN74164
differential amplifier 103 National Semiconductor LM370 amplifier
106a Signetics N5558 diodes 106b Motorola IN663 transistor 106c
Fairchild 2N3643 transistor 106d Fairchild 2N3638 transistor 106e
Fairchild 2N4913 transistor 106f Fairchild 2N4904 resistor 106g
2000 ohms 1/2 watt resistor 106h 560 ohms 1/2 watt resistor 106i 10
ohms 1/2 watt
In FIG. 6, an ink jet unit 200 is mounted on a pivotal support
including bars 201. A serrated plate 202 is moved past the jet unit
to produce vibration indicated by arrow 203. The document 28 moves
past the droplet path to intercept the droplets. As a result, a
cyclic wave may be printed on the document.
The charging and deflection and ink catching components of the
system have not been shown in FIG. 6. It will be understood,
however, that FIG. 6 illustrates a mode of lateral vibration of the
ink jet cyclically to vary the trajectory of the droplets. With a
droplet stream, the control system may be as in FIGS. 1-3 for
selecting portions of the stream to be printed.
In FIG. 7 a further modification for producing lateral vibration of
the ink jet has been shown. In this system, a disk 210 is mounted
on helical springs 211 and 212. The springs 211 and 212 may be
formed of a magnetostrictive or piezoelectric material. Such
springs suitable energized will cause the disk 210 to vibrate with
nozzle 214 forming part of the vibrating system. Thus, a further
means for producing lateral vibration may be employed.
In FIG. 8 the jet system in or a part of a carriage 220 is mounted
on a pair of guides 221 and 222. Guide 222 has helical grooves
therein which cooperate with a follower (not shown) in the carriage
220 in a manner well known in the art to cause translation of the
carriage 220 in the direction of arrow 223 and to return the
carriage back to an initial position. In such system, the document
28 is fixed while the system embodying the present invention has
its ink jet movable on a carriage.
Here, the charging plates 24 and 25 and the deflection plates 26
and 27 are also illustrated and mounted for movement along with
carriage 220.
A further mode of providing for translation of the printing unit is
illustrated in FIG. 9 wherein a carriage 230 is mounted on a beam
231 by means of rollers 232. The carriage is then driven under the
control of a belt 233 to reciprocate the carriage as indicated by
arrow 234.
In FIG. 10, the printing of alphanumeric characters has been
illustrated. In this embodiment, a 5 .times. 7 matrix is employed.
Each drop is then selected in a segmental basis as above described
so that any one of the segments of the trajectory waveform may be
selected to result in the printing of a drop at a desired location.
In this embodiment, the gun 11 projects a stream of droplets in a
normal trajectory plane. When printing is not to be permitted, the
deflection plates 26 and 27 cooperate with the charged droplets to
direct them into the catcher 29. Document 28 will move in the
direction of arrow 270 as the charging plates 24 and 25 are
selectively connected and disconnected to the voltage source.
Having described the invention in connection with certain specific
embodiments thereof, it is to be understood that further
modifications may now suggest themselves to those skilled in the
art and it is intended to cover such modifications as fall within
the scope of the appended claims.
* * * * *