Note: Descriptions are shown in the official language in which they were submitted.
7~7~
INR JET PRINTER WIT~ DEFLECTED NOZZLES
Reference is made to Canadian Patent Application
No. 286,504, filed on September 12, 1977, entitled INK JET
PRINTER WIT~ DEFLECTED NOZZLES, RolE Erikson, Edward Zemke
and Kenneth Guenther, inventors.
This invention relates to ink jet printers and
more particularly to high speed repertoire printers.
As here used, the -term i'repertoire" implies that a
plurality of information or data items are rnore or less
permanently stored for future read out. When read out
occurs, alphanumerical symbols are printed in a prescribed
format, responsive to those information or data items. The
data in the repertoire storage may be changed, updated,
increased or deleted, in whole or in part, at anytime. For
convenience of illustration, the information or data items
are herein described as names and addresses printed on mailing
labels. For example, these could be the mailing labels on
magazines, envelopes, or the like. However, this reference
to "repertoire" or "labels" is not a limitation upon the
scope of the invention.
The inventive device may use an ink jet printer
head, of any suitable design. In particular, the jet
printer technology here used was pioneered by Hellmuth J
Hertz. Some of this technology is disclosed in Mr. Hertz's
following U.S. Patents 3,416,153; 3,673,601; and 3,737,914.
The technology is also described in a doctoral thesis en-
titled "Ink Jet Printing with Mechanically Deflected Jet
Nozzles" by Rolf Erikson for the Department of Electrical
Measurements, ~und Institute of Technology, Lund, Sweden.
The specific jet printer head used in one embodiment, actually
built and tested, is a galvanometer (Rart No. 60 72 235
E039E) made by Siemens - Elema AB of Stockholm, Sweden.
7~
The galvanometer has a mechanically oscillated ink
jet nozzle which traces a cyclically repetitive path above a
moving paper or other media. In a preferred form, the
"cyclically repetitive" path may be a sine wave; however,
other geometric wave forms may also be used. The ink jet
nozzle has an output stream of ink droplets which can be
modulated or controlled responsive to electrical signals
generated by a mi~roprocessor. The jet stream is modulated
by a selective diversion of an ink jet stream responsive to
an electrical field applied near the nozzle. Attention is
paid to oscillation of the nozzle, printing rate and paper
quality, and the density and sharpness of the desired
printing. The result is a printing of alphanumerical or
other characters, at a rate which is in the order of 250
characters per second per nozzle.
The ink jet is transformed by the galvanometer
into a stream of fine droplets which follow each other,
single file toward a medium, such as paper, magazine, or the
like. If a charged electrode is placed near the point of
droplet formation, each drop carries an electrical charge.
Since all droplet charges are the same, there is a strong
repulsion between the adjacent drops which break up the jet,
a few millimeters from the point of drop formation. Another
electrode is placed in the ink in the nozzle; therefore, by
controlling the voltage difference between the electrode
near the point of drop formation and the electrode in the
ink, the ink jet can be switched or deflected between the
two paths resulting in an on-off modulation of a trace
formed by the droplets striking the paper.
The jet nozzle may be mechanically deflected,
simultaneously with a modulation which occurs when the ink
jet is switched on or off~ Therefore, by using mechanical
deflection of the nozzle together with a simultaneous electrical
76
modulation of the ink jet drops, any desired form of graphic
characters may be printed. Since the jet nozzle may oscillate
at frequencies in th~ order of 2 kHz and since the upper
fre~uency limit of the intensity modulation is higher than
100 kHz, this method of printing has many applications,
especially in high speed printing. Also, the jet spray may
fall upon almost any surface, regardless of its texture.
Therefore, there is little need to maintain an
adequate backing or to otherwise hold the paper in such a
; 10 rigid or firm position that a type face may strike the paper
squarely. Accordingly, labels may be printed directly onto
magazines, newspapers, or the like. There is no need to
print on a paper label which is thereaftex glued upon the
magazine, newspaper or the like. Thus, there is a flexibility
wherein printing ~ay be applied to almost anything.
This fle~ibllity creates a new problem of stacking,
transporting and otherwise handling the rnedia. For example,
the thickness of any one magazine may vary substantially as
comp~red to the thickness of another supposedly "identical"
20 magazine. Also, the folded side of the magazine is generally J
thicker than the unfclded side. At another time, the same
printer may be called upon to print upon single sheets of
thin paper, for example. Here, the transportation char-
acteristics of the thin paper media are opposite to the
transportation characteristics of a magazine. The magazine
is bulky, and the overall thickness is difficult to precisely
control. The paper is thin, with closely controlled thickness.
The magazine is hard to pick up and transport since its
pages tend to separate; the paper is hard to pick up since
30 individual sheets tend to stick together. Hence, the media
transport mechanism for such a flexible printer tends to
have conflicting demand placed upon it.
-- 3
7~
Thus broadly, the invention contemplates an ink jet
printing head which comprises a housing completely enclosing the
head to establish an electrostatic shield around the head, at
least one slot in a panel of the housing, gutter means inside
the panel with the gutter means having an upstanding knife edge
adjacent the slot, at least one electrically char~ed electrode
adjacent the knife edge, and at least one mechanically oscillat-
ing jet nozzle means for directing a jet .stream of droplets
past the electrode and the knife edge to reciprocally sweep
back and forth through the slot responsive to the oscillations
of the jet. A means adjacent the jet nozzle selectively
imposes electrostatic charges upon the droplets in the jet
stream, with the charge on the droplets being neutral relative
to the charge on the electrode during printing intervals and
being high relative to the charge on the electrode during
non-printing intervals, and with the high charge diverting the
jet stream into the gutter means.
In keeping with an aspect of the invention, an
ink jet printer is driven responsive to a bulk data storage
medium such as tape or cards, or the like. A repertoire of
data is read off this storage medium and fed into a micro-
processor which controls a ganged multiplicity of ink jet
heads, to simultaneously printout a plurality of lines.
A transport mechanism picks up and transports the media~ ~
under the ganged jet heads. A numb~r of housekeeping functions ~;
are also carried out -to insure that an adequate supply of
ink is delivered to and collected ~rom the jet nozzles.
The nature of a preferred embodiment of the
invention may be understood from a study o~ the attached
drawings, wherein:
Fig. 1 is a perspective view of the front of the
inventive ink jet printer;
" . " ... . ~, . ~ ,, ,, . :
~L~9~6
Fig. 2 is a rear elevation of the inventive printer;
Fig. 3 is a layout of the control panel of the
printer, which helps explain its functions and control;
Fig. 4 is a perspective view of a media pickup
means and gate device;
Fig. 5 graphically explains how a stack of media
is automatically fanned to introduce air between adjacent
layers or sheets, to facilitate pickup;
Fig. 6 is a schematic representation of the media
transport mechanism;
Fig. 7 is a perspective view of a nip roller
support and height adjustment mechanism, adapted to work
with media having a non-uniform thickness;
Fig. 7A is a front elevation view of the mechanism
of Fig. 7;
Fig. 7B is a perspective view of the elevator used
in the mechanism of Fig. 7;
Fig. 8 is a perspective view of a coupling for
driving the nip rollers of Fig. 7 despite a non-alignment
of the nip roller axles;
Fig. 9 is a side elevation of the galvanometer
used to oscillate the ink jet;
Fig. 10 is a perspective view of a printing head
and part of its housing, the head featuring a plurality of
the galvanometers of Fig. 9, ganged to simultaneously print
a number of lines;
Fig. 11 is a cross section of a pair of electrodes
and thelr support, taken along line 11-11 of Fig. 10;
Fig. 12 is a perspective view of the top oE the
housing of Fig. 10 and of a pair of grounding electrodes and
surplus ink collectors, used in con~unction with the printing
head;
", "
Fig. 13 is a cross-sectional view of the electrode
structures which are provided when the top of Fig. 12 is
placed on the housing of Fig, 11;
Fig. 13A is a fragmentary perspective view of the
jet nozzle and porous electrode which illustrates how the
jet nozzle may be deflected to remove a drop formed thereon;
Fig. 13B is a plan view of the jet nozzle and electrode
of Fig~ 13A;
Fig. 14 is a schematic representation of an ink
management system used in the inventive printer;
Figs. 15-19 are a series of sketches showing how
an inventive ink cartridge is made for use in the ink
management system of Fig. 14;
Fig. 20 is a block diagram of an electronic control
system for driving and controlling the inventive printer;
Fig. 21 schematically illustrates the method of
ink jet printing, which occurs when the electronic control
of circuit of Fig. 20 drives the printer of Fig. l; and
Fig. 22 schematically shows how a single jet may be
used to simultaneously print a plurality of lines at a time.
General Description
The major assemblies in the inventive printer
(Figs. 1, 2) are media select and transport mechanisms, 50,
52, a control panel 54, electronic controls 56, a source 58
of ink pressure, an ink scavengering system 60, and an ink
jet printing station 61. Any suitable covers (not shown)
may be provided to enclose and protect both the structure of
the printer and the people working around it.
The media select mechanism 50 comprises a plurality
of upright guide posts 62, 64, 66, 68 mounted on the table
of the printer and near a reciprocally moving shuttle 70.
The guide posts 62, 64 may be moved back and forth in directions
~9~
A, B by loosening, moving and then tightening a pair of knobs
72, 74. This adjusts the distances between the posts 62, 64
and 66, G8 to fit the dimensions of -the media (not shown).
In a similar manner, the width spacing between the guide posts
may also be adjusted by any suitable means ~not shown).
The shuttle plate 70 is mounted on tracks attached
to the table, for reciprocal shuttle movement in direction
C, D responsive to motive power supplied by a motor 78 (Fig. 2)
mounted in the rear, left-hand portion of the printer housing,
as viewed in Fig. l. As the shuttle 70 moves in direction D,
a single media (e.g., a single magazine) is picked up and fed
through a gate means 80 and into the transport system 52.
Alphanumerical characters are printed on the media as it passes
under the ink jet printing station 61.
The printing s-tation 61 comprises a pair of rails
or arms 82, 84 extending transversely over the transpor-t
mechanism 52. A printing head 86 is mounted on these rails
82, 84 to move back and forth in direction ~, F. Conveniently,
a worker simply pushes the head 86 in one of the two directions
E, F, until it stands over a desired printing station. The
ink and electrical connections to the printing head 61 are
made via a cable 88, which is preferably weighted at 90 (Fig. 2)
within the cabinet so that there is no slack cable.
The operation of the ink jet printer is controlled
by push buttons and slide bars on the control panel 54, which
is shown in detail in Fig. 3. More particularly, there are
two groups of push buttons 92, 94, a pair of slide bars 96,
and a number of selectively lit signs 98. The push buttons
92 command the printer functions, such as: power on/off,
print, test, reverse print, zip code sort, zip code print,
back space, and tape code. The "print" push button causes the
printer to print from left-to-right; if the switch "test" is
pressed, the printer will output a standard test message which
-- 7
may be used for adjustments of the printer; the "reverse print"
enables the printer to print upside down and from right-to~left
(the control computer merely reverses the normal character
order while the media moves in an opposite-to-normal direction).
The "zip code sort" push bu-tton causes the printer to recognize
each new zip code, as it appears, so that media may be diverted
into suitable groups which are thereby sorted according to the
~ip code. Normally, the machine recognizes any changes in
zip code and signals these events. However, when the switch
"zip code sort" is pressed, the machine provides two different
outputs, depending upon whether the code change occurred in the
two last digits or the first three. If the "zip code print"
push button is operated, a suitable symbol or symbols may be
added to the last (or first) label in each new zip code, to
facilitate a mechanical reader to detect and sort according to
zip code changes, at some future time. The "back space" push
button causes the repertoire storage unit to back space and
again read out a previously read block of data. The l'tape code'l
push button enables the printer to accept different code formats.
It is presently thought that most of the codes will be in ASCII
(a copy of which is found in Fig. 1 of U.S. patent 3,386,553).
However, other codes are also used and this push button adapts
the printer to accept them.
The selectively lit signs 98 inform the operator if
the printer encounters any problems. For example, these signs
may say such things as "low ink", "replace gas supply", or the
like. Therefore, an operator observing the lit signs may either
service the printer or operate the push buttons in an appropriate
manner. Of course, these signs may also be color coded to
indicate the urgency of the action required.
The push buttons 94 enable a repairman to perform
housekeeping functions. A push but-ton marked "safe" may be
pushed so that the machine cannot operate in any manner
-- 8 --
~39~7~;
which might injure a person who is then working on the machine.
Another push button marked ljog'l causes the machine to make
very small, step-at-a-time movements so that the interaction
of all parts may be observed. The other two push buttons start
or stop the machine.
The slide bars 96 enable analog adjustments. For
example, they may select any appropriate distance between the
edge of a label area and the first character printed in that
area. Or they may adjust a feed rate to accommodate the
aifferences caused by different lengths of magazines or paper,
for example. The belt motor drives at a constant; therefore,
a shorter document can be fed at a higher rate.
MEDTA PICKUP GATE AND FANNING MEANS
Fig. 4 illustrates the gate 80 used to enable the
printer to pick up individual sheets and to fan the media. The
gate is able to accommodate such diverse media as paper,
magazines, or other media, which are picked up one at a time
and delivered to the printing heads.
; In greater detail, the two upstanding paper
guides 66, 68 are set apart a predetermined distance, which
coincides with the width of the paper or media. The inside
surfaces of the guides 62, 64, 66, 68 are lined with upstanding
bristles of a textured, fiberous material, which lining
terminates a distance H above the table level 102. The fibers
project toward the media, outwardly and perpendicularly away
from the side walls of the guides 62-68. Therefore, when a
supply 104 of paper or other media (Fig. 5) is stacked between
the upright guides 62, 64, 66, 68, the fiberous material 100 on
each of the guides projects far enough into the space G to cause
the paper to bow upwardly at the edges. The individual fibers
act as many small fingers to riffle the individual pages of the
paper. Therefore, the paper is fanned to introduce air between
~39~`77~ :
the individual sheets. Below the level H, the individual sheets
lie flat upon table 102, as at 106, ready to be fed into a
pick-up gate. In this flat reglon, enoug:h air has been
introduced between the individual sheets to facilitate the
pickup.
A shallow depression, dish r or -trough 108 is formed !
in the shuttle table, immediately in front o~ the pickup gate
110. The bottom of trough 108 is lined with vacuum holes 112
which suck the bottom sheet of the media down into the trough~
A pair of stationary, upright, spaced, parallel rails 114, 116
are positioned to rise on either side of trough 108. For course
gate adjustments, these guide rails may be moved up or down
by any convenient distance to provide clearance spaces 109,
111 which is just wide enough to allow one media to pass
-therethrough. Vertically sliding between rails 114, 116 is a
gate member 118 which may be finely adjusted to a~y convenient
height by means of a knob 120 connected to a feed screw 119.
The nut (not shown) for the feed screw is attached to the back
of gate 118. Thus, the side rails 114, 116 may be placed at a
20 coursely adjusted position to fix the spaces 109, 111. Then,
the fine adjustment gate 118 may be raised or lowered until
the space 110 becomes exactly the distance required to pass only .:
a single paper, magazine, or other media, when it is sucked
down into trough 108.
NIP ROLLERS, TRANSPORT, DRIVE, AND SUPPORT
A pair of nip rollers 122-128 are mounted on :~
opposite sides of the vertical gate rails 114, 116~ The upper
nip roller 122 or 124, in each pair, is above the table 102
level and the mating lower nip rollers 126, 12B are below the
table level. The nip o~ the rollers is horizontally opposite
the gate 109-111, and spaced apart by a distance somewhat less
than the thickness of the media then passing through the jet
, 1 0 - ' ''`
76
in printing machine. This way, the shuttle 70 reciprocally
moves back and forth in directions C, D. Each time that it
moves in direction D, a paper, magazine or other media is
pulled down by the vacuum in trough 108 and pushed through
gate 118. As this is done, the paper, magazine or other media
is caugh~ in the nip between the nip rollers 122-128 and
propelled toward a number of conveyor belts. The supply of
air to vacuum shoe 108 is controlled by an electrical valve.
The switching of the valve is done by means of two optical J
interrupters, the position o~ which can be adjusted by knobs
113, 115. At a certain position during the back stroke in
direction C, determined by switch 115, the valve connects a
vacuum source to shoe 108, to enable a catching oE the material
during the forward stroke D at a point de-termined by switch 113,
the valve switches again and connects some air pressure from
the pressure side of the vacuum pump to push the paper off
the shoe 108.
The nip rollers must be independently adjustable,
in a vertical direction to accommodate a folded paper, a
ma~azine, or other media of uncontrolled thickness. For
example, if the folded side of a magazine is on the right
(as viewed in Fig. 4), the nip roller 124 must move upwardly
further than the nip roller 122 moves because the fold makes
that side thicker than the other or open side. Moreover,
it may be necessary for both rollers to jiggle up or down as
the magazine passes between them since some individual
magazines are randomly thicker than other magazines in the
same printing runO
There are other problems since nip rollers having
different diameters also have different linear speeds, at the
peripheries of their tires. If uncorrected, the upper and
lower rollers would tend to skuff or abrade the media as it
passes between them. If a multisheet media (such as a
-- 11 --
~9~q~7~
.
magazine) is passing between the nip rollers, an~ skufing
would tend to peel back some pages, which would probabl~ jam
in gate 110. ~ccordingly, the nip roller/ transport, drive,
and support assembly is adapted to overcome all of these and
similar problems.
Fig. 6 shows the power train for drlving the trans-
port mechanism 52. The primary motive source is a motor 130
coupled to drive a shaft 132 having a number of pulley wheels
~such as 133) mounted thereon, to turn therewith. Trained
over each pulley wheel is an endless belt (such as 134)
which runs in direction I. As belts 134 run, they turn a
roller 136 located near the output of the nip rollers 122-
128. (The individual belts may be moved toward or away from
each other, by manipulation of handles 138 (Fig. 1) which
control the spacing between the pulleys on shaft 132. Idler
140 (Fig. 6) adjusts belt tension).
A pulley wheel 142 at the end of roller 136 turns
with it, as it is rotated by the endless belts. A belt 144
transmits the power of the turning roller 136 from pulley
wheel 142 to a mating pulley wheel 146. To prevent slippage,
both of the pulleys 142, 146 may have upstanding teeth and
belt 144 may have mating involute teeth. The pulley 146
is coupled to a first gear 148 beneath table level 102 ;
meshing with a second gear 150 above the table. The gear
148 turns a shaft 152 mounted under table 102 for rotating
the lower nip rollers 126, 128. The gear 150 is connected
through a Bowden cable 154 to drive the upper nip rollers
122, 124. Since the Bowden cable is flexible, the upper
nip rollers are free to be moved up and down without regard
to axle alignment.
One in each mated pair of nip rollers has a
diameter which is larger than the diamPter of the other
mating roller. For example, each of the lower nip rollers
- 12 -
"''`~ ~
7~
126, 128 may be a little larger than each of the upper nip
rollers 122, 124. Thus, the linear speed at the tire periphery
of the lower nip rollers is always slightly faster than the
corresponding linear speed of the other nip roller.
A differential 156 may be interposed between the
power trains driving the upper and lower nip rollers. Pulley
1~6 may be integral with the housing of the differential.
Accordingly, both upper and lower nip rollers may be driven
from the same source. When the slower of the nip rollers
falls behind the faster, the differential 156 enables the
nip rollers to turn at different speeds and thereby
prevent skuffing the media or peeling back the pages of a
magazine. When the slower of the nip rollers catches up,
it is positively driven via the involute toothed belt 144
and the associated two pulley wheels 142, 146. This way,
both the upper and lower nip rollers 122-128 may be positively
driven and still may experience totally different driving
conditions without damaging the media in any way.
The nip rollers may be moved up or down, indepen
dently of each other. Usually, this movement is made as
part of the initial set up for any given printing run.
Thereafter, it is not necessary to reset them until the
physical characteristics of the media change. In greater
detail, the two upper nip rollers 122, 124 are independently
mounted in bearings 158, 160 upon plates 162, 164 on opposite
sides of the gate 118. Each of these plates is suitably
mounted for individual up or down motions, to form individually
adjustable yoke members. One of the yoke members 164 has a
horizontal support 166 firmly attached thereto, as by welding,
bolting, or the like. The other yoke member 162 is separate
- from support 166. However, a stud 168 integrally formed on
support 166 projects horizontally into an opposing cavity in
yoke member 162. An eccentric cam 170 is horizontally
- 13 -
mounted on the side of yoke 162 opposite the cavity and
controlled by a lever 172. When lever 172 swings upwardly
in direction K, the associated eccentric cam 170 moves to
loosen the stud 168. Then, the nip roller support yoke
members 162, 164 may be moved up or down relative to each
other. Thereafter, the lever 172 is swung downwardly in
direction J, and the eccentric cam 170 locks against stud
168 on the horizontal support member 166. The two yoke
members 162, 164 are then locked together.
This way the vertical spacing between the two
mated pairs of nip rollers 122, 126 and 124, 128 may be
adjusted independently. Therefore, a magazine, for e~ample,
feeds smoothly between the nip rollers even though the
folded edge is much thicker than the opposite edge.
A knob 172 may be turned in order to adjust the
vertical disposition of the yoke members 162, 164 after they
have been independently adjusted and locked together. As
best seen in Fig. 7B, there are two spaced parallel, vertical
plates 174, 176, each having an upper inclined plane and
a threaded hole extending horizontally through it. These
planes are abLe to slide back and forth in directions L, M,
on a shelf 178, which is part of the ground assembly 180,
182 that supports the yoke members 162, 164. Each of the
inclined plane plates 174, 176, has an associated threaded feed
screw 184, 186 which e~tends through the horizontal hole
in the plate. Knob 172 is attached to the end of one of
these feed screws. A pair of meshing gears 185, 187 are
mounted on feed screws 184, 186. Therefore, as knob 172
rotates one way, feed screws 184, 186 turn in one set of ~
30 directions and the inclined plane plates 174, 176 approach
each other and as knob 172 rotates the other way, the plates
move apart.
A follower 190 rides on the two inclined p:Lanes
of plates 174, 176. As the inclined planes on the plates
la,
:` ~al9~77~
approach each other, the follower 190 moves upwardly
(as viewed in Fig~ 7B). As the planes move apart, the
follower 190 moves down. The vertical position of the yoke
162, 163 is controlled by the follower. Therefore, after
the yoke members are locked together by cam 170, they may
be raised or lowered to place the upper nip rollers 122,
124 precise distances from the lower nip rollers 126, 128.
In order to accommodate minor variations in thick-
ness between individual magazines in the same printing run,
10 the follower 190 rests on a spring loaded plate 192 tFig. 7A)
connected between yoke members 162, 164. ~ bolt 194 passes
upwardly from horizontal support member 166, through the
entire elevation control assembly to the plate 192. A nut
196 on the end of bolt 194 abuts against plate 192 and
limits vertical motion of the upper nip rollers 122, 124.
Coaxial with bolt 194 is a coiled spring 198 which
extends between the support member 166 and the upper plate
192, in order to urge the nip rollers 122, 124 downwardly.
Beneath the spring 195 is a thumb wheel 200 for adjusting
the spring tension. ~hen the forces urging the nip rollers
apart exceeds the spring tension, upper nip rollers 122,
124 may move upwardly in order to provide strain relief.
Means are provided for transmitting rotary driving
forces between the two upper nip rollers despite misalignment
of their axles, owing to the independent vertical adjustments
of the individual rollers. It should be apparent that the
rotary power transmitted to -the upper nip rollers 122, 124
creates a problem since the two bearings 158, 160 may or
may not be aligned. Therefore, an eccentric drive coupling
30 202 tFig. 8) is connected between the axles 201, 203 of the
two nip rollers. In one embodiment, this coupler is Part
No. lEl 15-14-6 made by Schmidt Couplings Inc. of 4298 East
Galbraith Road, Cincinnati, Ohio. However, there is a
problem that a Schmidt coupler is not normally able to
interconnect two axles having co-axial alignment, and it is
quite possible that axles 201, 203 will be aligned on many
occasions.
In general, a Schmidt coupler comprises three
similarly shaped and sized pentagonal plates 204, 206, 208
mounted in a spaced parallel arrangement. Ten individual,
elongated arms (as at 210) are pivotally interconnected at
each of their ends to the corresponding apexes of adjoining
plates 204, 206, 208. For example, the lower end of arm
210 is pivotally connected to plate 204 and the upper end
is pivotally connected to plate 206. A~le 201 of nip roller
122 is clamped to the left-hand pentagonal plate 204, and
axle 203 is clamped to the right-hand pentagonal plate 208.
The center pentagonal plate 206 is pivotally connected to
both of the outer plates 204, 208 via arms 210. The end
212 of axle 201 has an eccentric or crank arm. This means
axle 201 may assume any vertical position (aligned or non-
aligned) relative to axle 202, and yet the Schmidt coupling
may still interconnect two non-aligned axles 212, 203,
which the Schmidt coupling must do in order to transfer
rotary power between outer plates 204, 208. The throw
distance N of the eccentric or crank arm 212 is equal to or
greater than the minimum amount of axle misalignment
required by the Schmidt coupling.
INK JET PRINTE~
After the paper, magazine or other media has passed
out of the nip rollers, it is carried by the running belts
(such as 134, Fig. 1) past the printing station 61. The
details of the printing head 36 are shown in Figs. 9-13.
The Siemens-Elema galvanometer (Part No. 60 72 235
E039E) is seen in Fig. 9. In greater detail, characters can
- 16 -
be printed with a single intensity modulated ink jet, if the
direction of that ink jet is mechanically changed in an
oscillatory fashion to follow a cyclically repetitive path,
such as a sine wave, for example. The oscillatory movement
is most conveniently obtained by mechanically oscillating
the nozzle producing the ink jet. The quality obtained by
the ink jet technology is dependent on the writing speed,
(i.e., the speed at which the paper moves and at which the
ink is traced on the paper). For the best results this
writing speed should be in the range of 3 - 12 m/s.
If the cyclically repetitive path is a sine wave
traced over a paper, the oscillating jet nozzle has a -~
writing speed VS given by:
Vs = -2-w x coswt
where: A is the width of the scan and w is the os-
cillating frequency.
From this equa-tion, for practical, usable widths A, an u~per
frequency limit of about 1.5 kHz is sufficient for oscil-
lating the ink jet nozzle, i a sine wave is used as a
driving force. However r it should be understood that other
suitable oscillation shapes may also be used, but a larger
bandwidth may be required~
The ink jet producing part of the galvanometer
(Fig. 9) comprises a very thin glass tube 214 with an outer
diameter of about 100 ~m, fix mounted at one end in the
galvanometer housing 216. The other end 218 of the glass
tube 214 is bent at approximately 90 and narrows to a
nozzle for producing a jet. A stream 220 of droplets flows
from this jet 218 toward the paper or media. Coaxially
mounted on the tube 214 is a small, cylindrical permanent
magnet 224~ polarized along its diameterO The magnet 224
is situated between a pair oE pole pieces 225, 226 (shown in
- 17 -
detail at 227) of an electromagnet 228. The magnetic field
turns the magnet with a galvanometer action and thereby
deflects the nozzle 218. The restoring moment of the
magnetic and nozzle system is caused by the torsion of the
glass tube as it twists responsive to energiza-tion of coil
228. The ink entering and passing through the glass rod 214
if filtered at 230. Spring loaded contacts 232 enable the
galvanometer assembly to be snapped into or taken ~rom the
printer.
A pair of electrodes 233, 235 are mounted on the
bottom of the galvanometer to form a gap P, through which
the ink jet stream 220 passes~ A solder terminal or lug
237 is formed on the opposite end of the electrode 233.
Therefore, a wire may be connected from the electrode 233
to the microprocessor so that the ink jet stream 220 may
be modulated with an ele~trical charge. Unlike most ink jet
printers, the jet stream is uncharged when printing and
charged when not printing. This way there is a simple on/off
action, and closely controlled analog currents are not required.
The printing head 86 (Fig. 10) includes a plurality
of galvanometers, each similar to the one seen in Fig. 9.
Each one of these galvanometers prints a separate line of
characters on the label. ~
The printing head 86 comprises a six-sided, outer .
~; metal housing 234 which completely encloses all galvano-
meters and protects persons using the equipment from high
electrode voltages. Fig. 10 includes the top and two end
panels of the housing. The two side panels of housing 234
are removed in Fig. 10 so that the parts may be seen, and
the top housing panel 236, is seen in Fig. 12. Three ink
jet streams (such as 220) pass from galvanometers 244, 246,
248 through slot 240 (Fig. 12) when the top is in place.
Two other ink jet streams from galvanometers 250, 252, on
- 18 -
f~.
~39~76
the far side of the housing 234, pass through slot 241.
Centrally located within the cabinet 234 is an
insulating plate 242, which preferably is made of any suitable
plastic material. A plurality of high voltage electrodes
254, 256 are suspended from opposite sides of the insulating
plate 242. Five galvanometers are supported from the top
plate 257 (five galvanometers are provided since ~his number
is sufficient to simultaneously print five lines of characters
forming: a name, a three-line address, and any suitable code,
such as the explration date or account number of a magazine
subscription, for example). As should be apparent from a
study of Fig. lO, the five galvanometers 244-252 are at
staggered locations on opposite sides of the central panel 242.
This makes a more compact structure.
Alternatively, a single jet may sweep over the entire
width of a label area and simultaneously print any suitable
number of lines. Thus, five jets are here shown only to speed
the printing process. Hence, any suitable number of jets may
print any suitable number of lines.
An electric fan 253 is provided to drive filtered air
into the housing to create slightly hiyher than atmospheric
pressu~e therein. Hence, any foreign substances near the jet
nozzles of the galvanometers are blown out of --and not sucked
into-- the housiny. Also, this arrangement enables the
entire housing to be well grounded so that workers do not
encounter the high voltages on electrodes in the housing.
Two porous electrodes 254, 256 are mounted on the
opposite sides of the central insulating plate 242. These
electrodes extend adjacent the full length of the printing
30 slots required for the five galvanometers 244-252. Therefore,
the ink jet streams from each of the five galvanometers must
pass adjacent these electrodes 254, 256 before they reach
the slots 240, 241. A high voltage electrical wire 25~ is
- 19 -
(~
77~;
connected through a passageway in central insulating plate
242 to electrodes 254, 256, in order to apply a high potential
to them.
A vacuum line 260 is connected through a passage-
way 262 (Fig. 11) in insulating plate 242 to cavities 264,
266 behind the electrodes 254, 256. Therefore, any ink
falling upon the electrodes 254, 25~ is sucked through the
porous electrode material, into the cavities 264, 266, out
passageway 262 and vacuum line 260 to the spent ink sca-
vanging tank 268 (Fig. 1).
The bottom 236 (Fig. 12) of housing 234 includes
two more blocks 270~ 272, having mounted thereon two more
porous electrodes 274, 276, which are held at ground potential.
Blocks 270, 272, and insulating plate 242 are held in a
spaced parallel relationship (Flg. 13) when the bottom 236
is fi~ed in place on the housing 234. A gutter member 278,
280 is formed between each of blocks 270, 272 and bottom
panel 236. Each of the gutter members terminates in an
upstanding razor-sharp edge 282, 284 running closely adjacent
20 the slots 240, 241 through which the five ink jet streams pass.
A pair of porous blocks 288, 290 are interposed ~.
between the blocks 270, 272 and the gutter members 278, 280,
respectively, with the edges of blocks 288, 290 running
closely adjacent to and along the length of the razor-sharp
edges 282, 284. A vacuum cavity 292, 294 is formed in each
of the porous electrodes 274, 27~ and similar cavities 296,
298 are formed in each of the porous blocks 288, 290. Each
of these cavities is in communication with a vacuum channel
300, 3a2 in the blocks 270, 272. Therefore, any ink reaching
30 the electrodes 274, 276, porous blocks 288, 290, or gutters
282, 284 is drawing off through the porous material and into
the vacuum system. Vacuum tubes 304, 306, 307 connect the
vacuum channels 300, 302 to the spend ink scavenging tank
268 (Fig. 1).
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~76
The operation of the ink jet stream modu~ation is
illustrated in Fig. 13. (The term "jet stream" is intended
to cover either a stream or a spray, in any suitable form.)
Normally, the ink droplets are uncharged during printin~ so
that they pass through the slots 240, 241 to the paper 306.
Thus, for example, Fig. 13 shows switch 307 open so that wire
308 and jet stream modulating electrode 309 (Flgs. 10, 13)
are deenergized. Therefore, the`adjacent ink jet stream 310,
modulated by unenergized electrode 309 is shown in Fig. 13
as reaching the paper 306. However, the switch 311 is closed
so that wire 312 and electrode 313 (Figs. 10, 13 are energized~
to impart an electrostatic charge to each droplet in the ink
jet stream 220.
When an electrostatic charge is imparted to the
droplets of ink jet stream or spray 220, the potential on
electrode 254 repells and -the ground potential on electrode
276 attracts the ink, which is diverted and caught in the
gutter 284. It is important to note that the inventive system
applies the high voltage to the entire stream or spray in
aggregate. There is no effort to control the potential on
: ,~
individual droplets. This ma~es the control system much ~
simpler and the printing much more reliable. Accordingly, ;
a computer may apply signals simulated by switches 307, 311
to modulate the ink jet stream of droplets 220, 310, and
thereby write or not write on paper 306.
When the ink supply is shut off, a drop of ink may
grow at the tip of the jet nozzle, which will cause problems `
if uncorrected. First, the drop will tend to lessen the
spacing between electrodes 254, 276, for example. Then, the ;~
printer head may have to be shut down and cleaned. A second
problem is that the drop increases the inertia of the
oscillating sys~em. Therefore, the system would have some
new printing characteristics.
- 21 -
~9~7~7~
To remove any drop Erom the end of the jet noz~le,
a block of porous material 325 ~Fig. 13A) is situated close
to the nozzle. An outjutting part 327 oE block 325 is
positioned near the end oE an arc R over which the jet nozzle
swings during ~rinting. The side wall S of the part 327 lies
close enough to the nozzle to touch any drop ~orming thereon,
but far enough so as not to touch the nozzle itself.
Immediately upon its formation, the drop, if any, Eormed on
the end o~ nozzle 218 is sucked into this porous material 325.
Since the drop radius should not be larger than 200 ~m, the
distance Q in Fig. 13A is in the order of 250 ~m, somewhat
depending upon the positioning of the galvanometer relative
to gravity. Also, the control circuit may be adjusted to
produce momants acting on magnet 224 in order to either shake
the nozzle or to bring it closer to block 325 responsive to
; drop formation. If so, there will be a capillary action
between the drop on the jet nozzle and the porous block 325
in addition to a vacuumized cavity behind the block.
INK MANAGEMENT SYSTEM
.
The ink is supplied, under pressure, to the jet
nozzle in each galvanometer, via its individually associated
tubing 324 (Figs. 9, 10). The system for pressurizing and
transporting the ink is seen in Fig. 14. In greater detail,
the ink pressure is supplied from either oE two pressurized
nitrogen bottles 58A, 58B through a pressure sensor 323A,
a check valve 321, a valve 328, a regulator 326, and a sensor
323B to an on/o~-E valve 330 in the vacuum line and in parallel
therewith to a pressure tank 346. The pressure sensing device
323A senses when the nitrogen tank 58A (~or example) is
exhausted. Responsive thereto a sign 98 (Fig. 3) is lit on
the control panel and the pressure system is switched over to
the second nitrogen ~ottle 58B. A light 331 (Fig. 3) remains
776
lit on the control panel to identify the exhausted nitrogen
bottle, until it is replaced by a freshly charged one.
A va~uum is supplied over a path traced from a
muffler outlet 332 (Fig. 1), through a motor-driven vacuum
pump 334, a vacuum output 338 and a filter 336 to a vacuum
accumulator bottle 340. From there, a va~uum line 342 (Fig. 14)
runs by a ball valve 330A which is between the line and atmo-
spheric pressure and to the on/oEf switching valve 330B.
Therefore, line 344 may be either pressurized or held at a
vacuum, depending upon the position of the switching valve 330.
The output line 344 of the switching valve 330 i5
connected to the inlet of a pressure tank 346 via a sliding
valve 347 which either seats on "O" ring 349 or hangs down in
an open position. The valve 347 seats against the "O" ring
when pushed upwardly by a plastic bag 356. This valve
mechanically keeps the bag from being sucked into the vacuum
line 344.
The outlet 348 of pressure tank 346 is connected
to a stand pipe 350 rising inside the pressure tank 346 and
terminated by a tube 352. A floating ball valve 354 is
entrapped within the tube 352. An 1-0-l ring 357 is positioned
under ball 354 to seal it against tube 352. Surrounding and
sealed to the stand pipe 350 is a plastic bladder or bag 356
which may be filled with and emptied of ink. This bag 356
keeps the ink separate from both the pressurizing and vaccum
systems in order to prevent contamination of the ink with
foreign particles. Also, if any contamination should occur,
it is a simple matter to change the bag. When the level of
`; ink in bag 356 is higher than the end of the stand pipe 350,
ball 354 floats within tube 352 and the ink may run out line
348. However, when the ink falls to approximately the level
at the end of stand pipe 350, the ball valve 354 is pressed
down by the bag and seats itself upon "O" ring 357 and ink
may no longer run from outlet 348.
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~9977~
The user buys ink in a ~lastic cartridcJe 36Q which
is placed over a piercing receptacle 362 that makes a hole
in the bag. Preferably, cartridge 36~ is placed at a loca-
tion which is higher than tank 346. ~ suitable collar 364
seals the cartridge 360 to the receptacle 362 so that the ink
does not leak out the connection. A pressure sensor 366
detects the pressure in line 363 and ~ives a signal responsive
to decreasing pressure (down to vacuum), when the ink is
exhausted and the flow terminates. The signal is à lit sign
at 98 (Fig. 3) and any other suitable alarm such as a bu~zer
sound. ~ check valve 368 prevents ink flow back into the
cartridge 360 when tank 346 is pressurized. Line 372 leads
~ to each of the galvanometer nozzles. ~n line 372, a pressure
;~ sensing device 374 detects low ink and gives a suitable signal
on the lit signs 98 of Fig. 3.
The ink management and supply system operates this
way. The on/off switching valve 330 is set to connect vacuum
pump 60 to pressure tank inlet 344. The vacuum pump 60 creates
negative pressure inside tank 346, which opens check valve 368,
; 20 to draw ink from cartridge 360 into the plastic bag 356.
When the pressure tank bag 356 is filled with ink,
valve 347 is pushed shut and on/off valve 330B disconnects
the vacuum pump 60. The check valve 368 effectively terminates
flow from the ink cartridge 360 and substitutes therefor the
pressurized ink line 372 leading to the jet nozzles on the
galvanometers of Fig. 10. The pressure of the nitrogen gas
from one of the tanks 58 enters tank 346 via valve 347 and
squeezes the plastic bag 356, thereby forcing ink out the line
372 to the jet nozzles of the galvanometers. When the ink
supply in bag 356 is exhausted, floating ball valve 354 seats
on stan~ pipe 350. Pressure sensor 374 responds to the
resulting drop in line 372 pressure and causes the on/off valve
- 24 -
76
330B to switch and repeat the fill c~cle.
The construction of ink cartridge 360 is seen in
Figs. 15-19. Initially, the cartridge begins as a die cut
sheet 360a (Fig. 15) of plastic, twice as long as the final
ink cartridge. An upstanding collar 364 is welded to one
side of this plastic sheet. A small square flap 378 of
similar material is placed over the other side of the plastic
sheet blank 360a, opposite the collar 364. One edge 380 of
flap 378 is welded to blank 360a.
Next, blank 360a is folded along its center line
382, to take on the configuration 360b (Fig. 16). Then, the
periphery of the blank 360c is welded every place 384, 386
~; tFig. 17) except at fold 382 and neck 388. This forms a
completed flask-shaped cartridge with an open neck at 388.
A full charge or supply of ink is inserted through neck 388
: and into the flas~-shaped cartridge/ by any suitable means~ ~
Then, the neck 388 is welded shut. - -
When the ink cartridge is used, the collar 364 is
pressed over the plercing receptacle 362 (Fig. 18) which
forms a hole in the cartridge wall. The internal flap 378
raises and ink may be drawn from the cartridge through the
receptacle 362. After the ink supply is exhausted, the
cartridge is removed from a receptacle, the flap member 378
closes (Fig. 19) over the pierced hole and acts as a flap
valve to restrain further outward flow of ink.
ELECTRONIC CONTR(~L CIRCUIT
The computer-driven electronic circuit for control-
ling the ink jet printer is seen in Fig. 20. The principal
parts of this circuit are a repertoire data storage mechanism
400, a microprocessor 402, a character generator 404, output
buffer memories 406 individucally associated with each gal-
vanometer, and a clock pulse generator 408.
- 25 -
,~
~9~
Clock pulses ~or contxollin~ the electronic circuit
are seen at ~10. The alphanumerical character-forming ~atrix
is seen at ~11, and the printed lahels are represented at
412. The cyclically repetitive or mechanically oscillated
path followed by the ink jet nozzle is represented at 413
and the modulated ink deposited on paper 306 is shown at 415.
A sine wave at 415 is useful for explaining how
data is processed during the downswing and ink is deposited
during the upswing of the jet nozzle oscillations. The sine
wave shaped path traced by oscillation of the ink jet nozzle ~;
is indicated at 415 in order to show the principle of the
modulated ink jet. Mechanically, it is easies-t to implement
this sine wave path, but it has certain disadvantages. When
a sine wave is used, the writing speed of the ink jet on the
paper varies as the cosine of the deflection angle. There-
fore, a constant length pulse on the modulation electrode
generates a bar on the paper, the length of which is a function
of the deflection angle of the jet nozzle. Of course, this
non uniformity of printing time could be circumvented by
controlling the duration of information transmission to the
modulation electrode.
If the nozzle oscillation follows a triangular wave
pattern, a clock signal with a constant frequency could be
used. However, such a wave pattern demands an excessive
bandwidth and there is a phase change between the clock
signal and the mechanical oscillation.
The writing speed of the ink jet should be low to ;~
optimize the resolution and density of the print out. Thus,
a sawtooth-shaped oscillation pattern i5 suitable t since it
has the lowest possible writing speed for a fixed frequency.
However, the sawtooth scan requires a larger bandwidth for
the mechanical oscillation system.
- 26 -
~1;' "'
977~
Thus, the shape of the scan has to be a compromlse,
depending on the application.
The repertoire of data is ~tored in device 400
(here called a "tape deck'l), which may take any suitable form,
such as: perEorated cards or tapes, magnetic tapes, magnetic
typewriter cards, or the like. In one embodiment, it is
magnetic tape. This medium stores a repertoire of data which
may be changed, up-dated, increased or deleted, in whole or
in part. In the present example, each complete set of data
in the repertoire includes a subscriber's name, address, and
subscription number, which may be printed on up to five
separate lines. In addition, the data may also include
machine readable bar codes or mail sorting symbols.
, The tape deck reader may be any well-known device
for reaaing the storage media (e.g., a magnetic tape reading
head) and it need not be described here. -
The internal coding used for recording on the tape
deck depends entirely upon the nature of the storage media
and repertoire storage device 400. For e~ample, one manufac-
turer of magnetic typewriters uses its own code. Other manu-
~ .
facturers use other codes~ Therefore, the inventive ink jetprinter controls include any suitable number of code converters
418, 420 which are able to accept and decode the data read
from the repertoire storage. These code converters could be
;~ mounted on alternatively used printed circuit cards, which
~; may be substituted for each other. Or, they could be alter-
native circuits selected by one of the control panel switches
in Fig. 3. In any event, the data read out of the repertoire
; storage device at 400 is converted at 418, 420 into the well-
known ASCII code. In one embodiment, the tape buffer memory
422 is adapted to store a block of data relating to six labels,
each time that the repertoire memory 400 reads out.
- 27 -
.. :'"
776
The rllicroprocessox 402 ~ay be a~ny o;E the well-
known microprocessors which are`curxently a~ailable on the
open commercial market. In an embodiment actually built and
tested, an Intel ~080 microprocessor was used.
A suitable divide-by-nine circuit 421 is a galvano-
meter drive circuit which responds to a stream 425 of clock
pulses from clock generator 408. The divide-by-nine circuit
causes the ink jet 218 to mechanically oscillate backward and
forward, and thereby trace a sine wave path 424 (also shown
at 413) relative to a moving strip of paper 306. The output
of the divide-by-nine circuit, which drives the nozzles, is ~ -
shown at 417.
The instantaneous potentials applied to the elec-
trodes 309, 256 either deflect the ink jet off the paper
(jet stream charged) to not print or enable it to reach the
paper (jet stream not charged) in order to print, thereby
- forming traces of ink (as at 426) or spots of lnk (as at 428).
By inspection, it should be apparent that the stream of ink
droplets have been shown at 415 as hawing been deflected to
print the letter "A'l upon the paper 306, whlle the jet nozzle
oscillates and the paper runs under the nozzle. This letter
"A" is printed responsive to the character formed in the matrix
411.
Upon reflection, it should be apparent that the
torsion in the twisting glass tube 214 causes the nozzle
excursion to begin, speed up, slow, stop, reverse direction,
begin again, speed up, slow,..., etc. Therefore, near each
sine wave cres-t (at 429, for example) of the nozzle excursionr
the jet is traveling much slower than it travels at the mid-
swing ~at 431, Eor example). Accordingly, the microprocessor402 must modify its print cor~ands to account for
the location of the nozzle in its excursion (i.e., Eor the
instantaneous excursion speed).
- 28 -
:
9~76
The characters are formed in ciXcuit ~Q~, which
includes a 5 x 7 matrix, as shown at 411. Successive in~
stantaneous incremental positions in each upswing in the sine
wave of the noæzle excursions are represented by rows, at
"1, 2, 3,...9". These are the optional printing points. To
account for the slower nozzle excursion speed at the crest
(e.g., 42a) near the ends of the excursions, the first and
last matrix rows are duplicated. Thus, rows 1, 2 form the
same optional printing point at a sine wave crest at one end
of the jet nozzle excursion. Rows 8, 9 Eorm the same optional
printing points at a sine wave crest near the opposite end
.
of the jet nozzle excursions. This way, during time intervals
1, 2 and 8, 9 ink flows to the paper twice as long, as it flows
during time intervals 3-7, when the mid-swing jet nozzle is
traveling faster, as at 431, for example.
Successive upswings in the sine wave 424 represent-
ing the jet nozzle excursiolls correspond to the columns 1-5
in matrix 411 (Fig. 20). Therefore, the jet nozzle is control-
led to deposit ink at those incremental points in its succes~
si~e upswing excursion (as indicated at 419) which correspond
to the markings in columns 1-5 in matrix 411. Other alpha-
numerical characters are formed in the same way.
Each time that the repertoire memory 400 reads out
a block of data, buffer memory 422 stores the data required
to form up to 1000-characters, which is adequate for printing
up to six labels. This buffer stored data is thereafter read
out, a label at a time and transferred from circuit 422 to
the microprocessor 402, which is adaptea to store up to 256-
characters (i.e., enough characters for one label).
The microprocessor 402 operates under a program
stored at 423 to apply data to character generator 404 where
the row and column format is established, as shown at matrix
~C~9~7~
411. In addition, clock generator 408 supplies a steady
stream 425 of the clock pulses to the microprocessor 402 and
to shift registers ~06, which are indi~iclually associated
wi-th the five jet nozzles, two of which are shown at 427A, ..
427B. The character generator 404 supplies the data in a
single matrix column, associated with a first line of print-
ing to shift register 432, during a first clock pulse. During
the next clock pulse, the data in shif-t regis-ter 432 is
shifted to shift register 433 and data relating to a single
matrix column in the next line of printing is stored at 432.
In a similar manner, data representing each matrix column
and relating to each line of printing is also stored in each
of the individually associated shaft registers at 406. This
; data storage process is under control of a line selection
circuit 437.
The operation of the electronic control circuit is
best explained by the curves shown on Fig. 20. In greater
detail, the clock pul.se generator 408 applies a steady stream
425 of clock pulses to microprocessor 402, to shift registers
406, and to the galvanometer adjust and drive circuit 421.
The first nine pulses 502 cause a jet nozzle 427B (for example)
upswing because drive circuit 421 applies an outpu~ 417 of
one polarity to the galvanometer coil 504 associated with
the nozzle 427B~
During -the next nine pulses 506, the jet nozzle
427B has a down swing because circuit 421 applies an output
508 of opposite polarity to coil 504. The resulting mechanical
nozzle excursions are shown by curve 419.
A block of data is called up from the repertoire
memory 400, six labels at a time, and stored in buffer memory
422. Thereafter, this same data is transferred one label at
- 30 -
a time from the tape buf;fer memory 422 in-to a label memory
510 associated with the microprocessor 402. ~s indicated at
512, the micr~processor then applies the data in label memory
510 to the character generator 404 during the downswing period
506 of the jet nozzle.
. At 514, there are five small shaded squares which
indicate that the microprocessor 402 has trans:Eexred one
label block of data required to print five lines from memory
510 through character generator 404 to shift registers 406.
The data represented by shaded square "1" is stored in shift
`~ register 432 ~for example) and the data represented by shaded
square "S" is stored in shift register 436. In a similar
manner, data represented by shaded squares "2"-"~" is stoxed
in shift registers 433-435. The data storage occurred under
control of clock pulses 516, during the downswing portion 506 ~:
of the jet nozzle excursion.
During the next following upswing 520 of the jet
nozzle mechanical excursion, each jet prints out a line of ;~
printing responsive to the data stored in its associated
shift register 406. Thus, for example, nozzle 427A prints
out one line responsive to data stored in shift register 432,
and nozzle 427B prints out another line responsive to data
stored in shift register 436. Three other jet nozzles (not
shown in Fig. 20) print out three other individual lines
responsive to data stored in shift registers 433-435.
From Fig. 10, it will be recalled that the galvano- :
meters 244-252 for printing odd and even lines are staggered,
with respect to each other. Therefore, the paper 306 passing
under the printlng head encounters the ink jets :from the
galvanometers printing even lines before it encounters the
ink jets from the galvanometers print odd lines. Accordingly,
- 31-
.~ !
~c~s~ e
the drawing shows at 522 that the galvanometers of the jet
nozzles associated with the even lines are driven by clock
pulse"9" at a ti~e when the je-t nozzles associated with the
odd lines are being driven by clock pulse "1". This "9"
clock pulse delay coincides with the time required for the
paper 306 to travel from the position of the even jet streams
to that of the odd jet streams. As shown at 524, by way of
example, the even line ink jets are printing the sixteenth
characters in their lines while the odd line ink jèts are
printing the eighth characters in their lines. Thus, the
indi~idual lines of print are physically aligned even though
the jet nozzles are physically staggered.
Lines 526 illustrate manipulation of the data and
the operation of tape control circuit 528. Before the start
of these lines 526, it is assumed that a block of data for
printing six labels has just been transferred from the reper~
toire storage oE tape deck 400 to the tape buffer 422. At
time 530, the microprocessor 402 strobes OR gate 531 and ~ ;
oxders the tape buffer 422 to fetch the data required to print
the first label, which fetched data is stored in label memory
510. At time 532, the fetched data is withdrawn from
label memory 510 and used to print one label. As soon as
that first label is printed (at tlme 534), the microprocessor
402 again strobes OR gate 531 and orders the tape buffer 422
to fetch the data required to print the second label.
After the microprocessor 402 orders and the tape
buffer 422 completes the fetching of all the stored data
to print the sixth label (at time 536), the microprocessor
402 causes tape control circuit 528 to enable the tape deck
400, with a control signal. The tape deck 400 reads out the
amount of data re~uired to print six labels. F.ach time that
- 32 -
~`:
,. . ~;
776
the tape deck 400 reads out the data representing a single
character, it strobes the OR gate 531, and the tape huf~er
422 stores it.
When the tape deck 400 completes the transfer of
data required to print six labels, it recognizes an end of
block signal (at time 533). Thereupon, :Lt changes a charac-
teristic of its strobe signal, which the tape control circuit
528 recognizes. Responsive thereto, the tape control circuit
528 removes its enabling control signal from the tape deck
400, which stops sending. The tape control circuit 528 signals
microprocessor 402 to indicate that it may proceed to command
a printout of the first label. Thereupon, at time 540, the
microprocessor orders the tape buffer 422 to fetch the informa-
tion required to print the first label, which is done at
time 542.
I'he nature of the printed labels should become
apparent from a study of Fig. 21. Five jet nozzles 572, 576,
218, 576, 578 of the five galvanometers 244, 246, 2~8, 250,
252 (Fig. 10), respectively, are positioned over five separate
ones of the lines of print 580-588 to be printed upon the
label. Thus, each nozzle individually prints a separate line
o~ print. The label being printed is seen at 590~ A label
which has been completely printed is seen at 592.
Advantage may be taken of the ink jet's ability to
print graphic symbols as well as the more conventional alpha-
numerical symbols. For example, Fig. 21 includes a machine
readable bar code 594 which individually identifies the
par~icular label 592 to the microprocessor 402, or to another
computer (not shown). Thus, for example, business re-turn
postcards may be printed with the labels, including the bar
code 594. ~hen customers return the postcards, they may be
fed through automatic bar code reading machines. Responsive
- 33 -
7~
thereto, the reading computer is informed as to the identity
of customers who are most likely to answer an advertisement.
This wayr the repertoire data storage clevice 400 may be
controlled to read only those labels which have bar codes
corresponding to the bar codes on postcards that have been
returned. Thus, preferred data may be selec-tlvely called up
from repertoire storage responsive to a machine readable code.
To achieve a maximum printing rate, a plurality of
nozzles have been used, one for each line of print. However,
this multiple nozzle usage has also led to a complex control
system. Therefore, if a simplier control system is desired,
and if speed of printing is not absolutely esse~tial, trade-
offs may be made. For example, Fig. 22 shows a path traced
by a single jet as it sweeps over a plurality (six in this
example) lines of printing. As the jet passes over each line
o~ printing, it selectively deposits ink (or does not deposit
ink) in order -to make a plurality of lines of prin-t. Thus,
it is possible for any suitable number of nozzles to make
any suitable number of lines of print.
Those who are skilled in the art will readily
perceive various modifications which may be made without
departing from the invention. Therefore, the appended claims
are to be construed to cover all equivalents falling within
the scope and the spirit of the invention.
- 34-
