Note: Descriptions are shown in the official language in which they were submitted.
1046843
The present invention relates generally to print-
lng apparatus, and more particularly, to a high-~peed
matrix-type ballistlc impact print head.
Hlgh speed printers have been developed to accom-
modate the high output speed of in~ormation whlch can be
delivered by high speed information handllng systems. The
operational speed of such prlnters, however, 18 stlll a
limit~ng factor as to the total e~ficiency of an lnformation
handllng system ln that the prlnters are stlll relatlvely
slow when compared to the speed of the electronics gener-
atlng the in~ormation to be prlnted. Therefore, any im-
provement whlch increa~es the operatlonal speed Or the
printer has a marked effect on the overall efflclency Or the
operatlng system.
Printers employlng wire matrix balllstlc impact
prlnt heads provlde multlple hard coples of lnrormatlon at
a relatively high speed. These printers are characterlzed
ln that ror each prlnt cycl~ the prlnter does not print an
entlre character per impact but instead use an array of wire
otyll to prlnt selected comblnatlons of dots serlally onto
the reaordlng medlum 80 that a~ the recording medlum is
moved relative to the prlnt head, successive prlnt cycles
generate alpha-numerlc characters or other lnformatlonal
indicla.
One ma~or faotor dlctatlng the speed at which the
wlre matrlx ballistlc lmpact print head 18 capable oP oper-
atlng 18 the inertla as~ociated wlth the impacting styli
and the electromechanlcal stylus armatures. Print heads oP
this type typlcally use a separate electromagnetlc actuator
30 Por each stylus withln the prlnt head. A ma~or problem
encountered by the prlor art ln deslgning such heads 18 the
physlcal space requlred to accommodate these actuators
wlthin the prlnt head whlle malntaln~ng the lnertia oP the
1046843
print head as low as posslble. F~rther, electromagnetlc
actuator and stylus comblnatlon must be lndlvidually ad-
Justed. Tl~us, the ad~ustment for making all styll strlke
the record medium at approximately the same instant of time -
during a print cycle ls more complex, dlfflcult and tlme
consuming.
It is therefore an ob~ect of the present inventlon
to provlde a hlgh speed wlre matrix balllstlc impact print
; head wherein the actuators are arranged in a circle so as
to reduce the lnertia of the print head.
It 18 another ob~ect of the present invention to
provlde a hlgh speed wlre matrix balllstlc lmpact print
head whlch employs a unltary connector for holding the
armatures of each actuator ln proper posltlonal allgnment --
wlth lts assoclated stylus.
Another obJect of the present lnventlon is to pro-
vlde a hlgh speed wlre matrix balllstlc impact prlnt head
whlch employs a unltary connector for slmultaneously ad~ust-
lng all the actuators wlthln the prlnt head such that all
actuated styli strlke the record medium at substantlally
the same lnstant of tlme.
; It 1B stlll another ob~ect of the lnventlon to --
provlde a hlgh speed wire matrix balllstlc impact prlnt head
havlng a shock absorbing medlum for preventing bounce of
the actuator armature and/or stylus durlng the return por-
tlon of a prlnt cycle thereby preventing spurlou3 lmprint-
lng on the record medlum.
Brlefly~ the hlgh speed wlre matrix ballistic
print head lncludes a plurallty of wlre styll inserted for
30 movement wlthln a guide. The gulde translates the clrcul~r
~ormatlon o~ the impact recelvlng ends of the styll to a
stralght llne formatlon of the lmpact deliverlng ends of the
styll. An indlvldual actuator 18 provlded for engaglng the
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impact receiving end of each stylus. Aunitary connector is
also provided which includes means for holding the armature
in contact with a magnetic structure to form an actuator means
for holding each armature in proper alignment with its
associated stylus, means for simultaneously adjusting the air
gap between the armature and the electromagnet of the actuator,
means forming a reference surface for referencing all styli,
and damping means for eliminating bounce of the armatures and
styli after the actuators are deactivated during a print cycle.
An advantage of the present invention is that it
minimizes the variance inlength of the styli, thereby allowing
the simultaneous adjustment of the position of all styli
within the guide.
Another advantage of the print head is that the
print head includes a unitary multifunction connector instead
of the plurality of individual connectors as in the prior art,
thereby reducing the mass of the print head.
Still another advantage of the present invention
is the use of a unitary connector for providing simultaneous
adjustment of all actuators such that all of the styli strike
the record medium at substantially the same time.
More particularly there is provided a wire matrix
ballistic impact print head comprising: a base; N styli; N
electromagnetic structures mounted to said base, each said
structure having an outer pole, a center pole coupled to said
outer pole and a coil disposed around said center pole, each
said structure being associated with one of said styli; N
armatures, each being associated with one of said structures
and having a stylus engaging end; and a unitary connector
coupled to said base and having a central portion and N arms
extending radially outwardly therefrom, each of said arms having
means for holding one of said armatures in contact with the
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` - ~046843
outer pole of one of said structures to form an electromagnetic
actuator for transferring electromechanical energy to one of
styli.
The foregoing and other objects, features and
advantages of the invention will be apparent from the following
more particular description of a preferred embodiment of the
invention illustrated in the several figures of the drawing.
Fig. 1 is a perspective view of a print head in -
accordance with the present invention;
Fig. 2 is a cross-sectional view taken along
the line 2-2 of Fig. 1 illustrating the major components of the
print head;
Fig. 3 is a front elevational view of the guide
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1046843
shown in Fig. 1.
Flg. 4 is a plan vlew o~ the second translation
element of the guide shown in Fig. 3;
Fig. 5 is a plan view of the third translation
element of the guide shown in Fig. 3;
Flg. 6 is a bottom vlew ~ the fourth translatlon
element o~ the gulde shown ln Fig. 3;
Fig. 7 is a ~chematlc diagram 3howing the elec-
trical connectors of the actuator coils for the prlnt head
8hown in Flg. l;
Fig. 8 18 a plan view of the prlnt head shown in
Fig. 1 wlth the unitary connector and the armatures of the
actuators removed; and
Flg. 9 ls a bottom vlew of the unltary connector -
shown ln Flg. 1.
A prlnt head 10 ln accordance wlth the present
inventlon is shown in Fig. 1 connected to control circuitry
12 by means of the wl~es 14 and a plug 16. A ribbon 18 ls
dlsposed ln between the bottom of prlnt head 10 and paper 20.
Fig. 2 is a slde elevational cross-section view
lllu~trating the ma~or components of the print head 10.
Only one actuator and one stylus læ shown ln order to
simpllfy the drawing. It should be understood that nlne
actuator/stylus comblnations, identlcal in structure to
that shown in Fig. 2, are included wlthin the structure o~
print head 10.
A guide 22 is provided for recelving a stylus 24
and constraining lt to move along a curved path. The stylus
24 has a plastic cap 26 attached to its lmpact receiving
end to enlarge the area of the impact recelving sur~ace.
Stylus 24 has a spring 28 disposed at its upper end which
exerts an upward force upon cap 26 to resillently bias
stylus 24 upwardly relative to gulde 22. ~ulde 22 includes
1046843
four translational guide elements 32, 34 and 36, whlch
accomplish the translation Or the nine styll 24 from a
circulrr formation in the fir~t guide element 30 to a
3traight line formation in the fourth guide element 36.
The translation is accomplished by passlng each stylus 24
through a separate hole 38 in the first element 30, through
a separate hole 40 ln the second element 32, through a
separate h~le 42 in the third element 34 and into a deflned
posltlon withln a bearing 44 of the fourth element 36.
Flg. 3 lllustrates a front elevational vlew Or
gulde 22 showing a side wall 46 and a slde wall 48 termlna-
tlng ln the fourth translation element 36. Slde wall 46
and sidewall 48 are provlded with two sets of faclng grooves
50 and 54 and 52 and 56 for receiving the edge~ of gulde
elements 32 and 34, respectlvely. At one edge of sidewall
46 the grooves 50 and 52 extend deeper into the 31de wall
to form keyways for receivlng the locating key tabs 64 and
6~ Or guide elements 32 and 34.
A pair Or mountlng flanges 58 and 60 extend later-
ally from the upper ends of side walls 46 and 48. Gulde 22
18 conflgured circular in shape above flanges 58 and 60,
and terminates ln a clrcularly apertured surrace whlch
forms rirst guide element 30. A post 62 extends from the
~rst translation element 30.
Fig. 4 is a plan view of the second guide element
32 showing the styll gulde holes 40 arranged ln an elip-
tlcal pattern. The key 64 extends from the slde of element
32 to orlentate the placement of element 32 wlth~n gulde 22
as mentioned above.
3o Fig. 5 i9 a plan vlew of the thlrd guide element
34 showing the location of the styll gulde holes 42. As
- illustrated, the arrangement o~ the gulde holes 42 ls Or a
generally elongated oval configuratlon more or less
` 1046843
intermediate the el~ptical configuration shown in Fig. 4 and
the stra~ght line con~guration sho~n in Fig. 6. The key 66
extends from the si~de of element 34 for orientating the ~lement
within the guide 22.
Fig. 6 is a bottom view of the fourth guide element
36 of guide 22 showing the location of bearing 44 within guide
22. Bearing 44 aligns the lower ends, the impacting ends, of
the plurality of styli 24 in the desired linear arrangement.
The bearing 44 is of a material which resists wear, has a low
coefficent of friction and has a low coefficent ~f thermal
expansion.
Returning to Fig. 2, a base plate 70 is used as the
base for the construction of the print head 10. Plate 70 is
provided with a central aperture 72 through which the circular
portion of guide 22 extends. A plurality of holes 83 are
provided in the base plate 70 for mounting the nine actuators
thereto. Guide 22 is connected to base plate 70 by meaas of the
mounting flanges 58 and 60 which are affixed to the lower sur-
face of plate 70.
; A coil 74, a center pole 76, a L-shaped outer pole 78
and an armature 80 ~o~ the electromagnetic actuators used in
the print head. A hole 82 is provided in the horizontal leg of
the L-shaped outer pole 78 for receiving the lower extremity of
center pole 76. ~ole 82 has a diameter which is the same as the
outer dimension of center pole 76 so as to p~ovide a forced fit
therebetween. The center pole 76 of each actuator has a threaded
lower end 84 which extends through the hole 83 in base plate 70.
The center pole 76 and outer pole 78 combination is held in place
~y a nut 86 threaded onto end 84.
A wiring/connector board 88 tsee also Fig. 1~ has an
opening 90 provided therein for receiving an outer pole 78.
Board 88 also has an apeEture 92 through which the
1046843
circular portion Or guide 22 extends. Nlne additlonal holes
93 are provided ln board 88 through whlch the nlne center
poles 76 of the nine actuators pass. Coil 74 is mounted
around the center pole 76 on each actuator and wlred to
the wiring/connector board 88.
Flg. 7 ls a schematlc dlagram lllustratlng the
electrlcal connectlon Or the actuator colls 74 to the board
88. The nine colls 74 are wired with one end Or each coil
74 commonly connected and the other end Or each coil 74
10 wired to a separate connection polnt on edge connector 91
which 1B formed lntegral wlth board 88 as shown ln Flg. 8.
In Flg. 8 a plan vlew Or the prlnt head 10 ls
3hown wlth armatures 80 and a unltary connector 94 removed.
In essence, Fig. 8 lllustrates the constructlon Or the print
head 10 up to the polnt heretofore descrlbed. The nlne
styll heads 26 are shown posltloned above the first gulde
element 30 of gulde 22. Board 88 ls shown mounted between
the colls 74 and the magnetlc structures formed by the
center poles 76 and the outer poles 78 of the nlne actua- -
20 tor~. Mounting holes 95 are provlded ln base plate 70 ~or
mountlng the completed prlnt head 10 to a prlntlng sy~tem.
The post 62 of` gulde 22 has a threaded hole 96 provlded
there ln.
Returnlng to Flg. 2, the unitary connector 94 18
mounted by mean~ Or a screw 97 and washer 98 to the post
62 Or guide 22. Connector 94 has a clrcular cnntral por-
tlon 100 wlth an annular groove 102 provlded ln its bottom
sur~ace. An 0-rlng 104 ls lnserted ln groove 102 to act as
a shock absorber and to provlde a reference surface rOr the
30 stylus strlklng ends of the armatures 80.
Nine arms 106 extend rrom central port~on 100.
Each arm 106 has assoclated with lt a rirst armature re-
celving ~tructure 108 and a second armature receivlng
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iO46843
structure 110. One end of each armature 80 ls recelved and
held in place by structure 108 and the other end of each
armature is received and gulded by structure 110. Where
c onnector 94 is installed in the positlon shown, arms 106
apply forces to the cantilevered dlstal ends of the arma-
tures causlng the ir stylus lmpactlng ends to rotate about
the fulcrum formed by the top edge of pole 78 and upwardly
lnto engagement wlth O-rlng 104. The heads 26 of the styli
24 are maintained in contact wlth the ends of armature~ 80
by means o~ the forces applled by the springs 28.
Fig. 9 ls a bottom view of the unitary connector
94 showlng one armature 80 located ln posltlon relative to
one of the arms 106. On lts outermost end, the armature
80 has notches 112 and 114 which mesh wlth first and second
walls 116 and 118 of the flrst recelvlng structure 108 of
arm 106. The central portlon 100 has nlne armature re-
celvlng ~tructure~ 110 formed around its perlphery. Struc-
ture 110 ls formed by flrst and second walls 120 and 122.
At lts lnnermo3t extendlng end 126, armature 80 ls narrowed
80 that lt passes between the two walls 120 and 122 of the
recelving structure 110. T,le O-rlng 104 provldes a refer-
ence surface against whlch all of the armatures 80 are
referenced.
TJnltary connector 94 serves six separate and dls-
tlnct function~. Fir~t, lt holds each armature 80 in
contact wlth outer pole 78 (at polnt 124) ~o as to complete
the magnetic c1rcuit of the actuator as u~ed w~thin the
print head 10. Second, lt acts as a resillent, force
applying member applying a m,oment to armature 80 causing lt
to tend to rotate about the outer p ole 78. Armature 80
ls thereby rockably mounted upon pole 78 wlth lts narrow
end portlon 126 ln contact wlth the reference surface
formed by O~rlng 104. Third~ the unitary connector acts
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as a means ~or aligning the end 126 of armature 80 with the
head 26 of stylu~ 24. Thls allgnment feature prevents
undeslred lateral movement of armature 80 and insures that --
armature 80 is in proper allgnlng contact with head 26.
Fourth, connector 94 acts as an ad~usting m~ans for simul-
taneously ad~usting the alr gap between each of the arma-
tures 80 (at point 128) and the correspondlng center poles
76 of the respectlve a¢tuators. As a result of thls ad-
~ustment, the positlon Or all the styll 24 are unl~ormly
ad~usted wlthln gulde 22. Flrth, connector 94 rorms a
reference surface agalnst whlch the armatures 80 and head
26 o~ styll 24 are referenced such that all actuated styll
24 lmpact the record medlum at substantlally the same
instant of time durlng a prlnt cycle. Slxth, the unltary
connector 94 includes a shock absorbing 0-ring 104 whlch
absorbs the energy o~ the armatures 80 and styli 24 as they
return to their rest positions when the actuators are de-
activated. The absorbtlon of the klnetic energy withln a
~rticular armature 80 and stylus 24 at the end of a prlnt
cycle prevents the armature 80 or the stylus 24 from bounc-
lng and thereby cau~ing spurlous lmprlnts followlng the
print cycle.
Returning to Fig. 2, the screw 97 is passed
through hole 130 and tlghtened into post 62. A~ screw 97
is tightened, the alr gap between center pole 76 and arma-
ture 80 wlll decrease. At the same tlme the mo~ent exerted
on armature 80 by arm 106 18 lncreased. By the Judiclous
ad~ustment of screw 97 an optimum settlng can be obtained
ror transmlttlng the most deslrable amount of energy into
stylus 24 by armature 80 whlle malntainlng a deslrable
speed o~ return Or armature 80 to lts rest posltions.
In the alternatlve, the two-pie¢e structure Or
the outer pole 78 and center pole 76 could be replaced by
104684U
a ~lngle, cast structure of sultable material. Further, if
lncreased efflclency of the magnetic circuit is desired,
addltional outer poles could be designed lnto the actuator
t~ improve the magnetic circuit associated with the actua-
tor. Here again, the multi-pole structure could be con-
structed of a plurality of separate elements or could be
made of a single cast structure o~ proper material. The
base plate 70 could also be included into any casting so as
to lower the cost of manufacturing.
Referring to Flg. 1, print head 10 is capable of
generatlng nlne impresslons during each prlnt cycle. Alpha-
numerlc characters or other lnformation i9 generated by a
sequence of print cycles. For example, the letter "E" is
formed by selectively activating various comblnatlon~ of
the nlne styli 24 durlng five separate print cycles.
Normally, the top ~even styli 24 are u~ed to ganerate
letters having no below-the-line pro~ections. Letters re-
qulrlng below-the-llne formatlon are prlnted using ln addi-
tlon the lower two styll. An example is that lllustrated
20 by the lower case letter "g".
me control circuitry 12 selects which combination
of the nlne styli 24 will be actuated durlng each print
cycle. In between each print cycle, the print head 10,
in one printer embodiment, is moved one print increment
wlth respect to the paper 20 and the ribbon 18. However,
the relative movement can be made either by movlng only
print head 10, or by moving only paper 20 and ribbon 18,
or by moving the print head 10 and the paper 20 (and the
rlbbon 18).
The smaller the print lncrement, the greater the
resolution o~ information imprinted on paper 20. me
printing speed of print head 10 allows high resolution
information to be generated within a reasonable time. T;he
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information generated may take the form o~ both upper and
; lower case printed letters, script, plctures, figures,
mathematical notations, etc. - -
Referrlng to Fig. 2, when the coil 74 is ener- -
gized~ a magnetic flux is created which will cause armature
80 to be drawn into contact wlth center pole 76. The move-
ment of armature 80 will transmit energy into stylus 24
causing the stylus 24 to move downwardly through guide 22.
The force imparted into stylus 24 causes it to move agalnst
sprlng 28 and its lnertia causes it to continue to move
downwardly out of contact wlth armature 80 after the
armature bottoms out against pole 76. The impact delivering
end of stylus 24 extends beyond bearing 44 and strikes the -
record medium cau ing a dot to be imprlnted. The energy
stored in the moving stylus 24 iæ partlally absorbed by the
lmpacted medium and partially returned to stylus 24 aiding
spring 21-in returnlng stylus 26 to lts rest posltion.
At approximately the same time that ttylus 24 is
lmpacting the record medium, the coil 74 is de-energized.
The moment exerted on armature 80 by arm 10~ causes it to
rotate away ~rom the center pole 76 and to return into
conta¢t with 0-ring 104. The energy in the returning
armature 80 and the stylus 24 is absorbed by the dampening
material of the 0-ring 104 thereby preventing bounce Or
either armature 80 or stylus 24, thus preventing spurlous
imprints to be made during a prlnt cycle.
It has been found that optimum energy iB trans-
mitted into the stylus 24 when the actuator's air gap ls
set such that the impacting end of the armature 80 moves a
3o distance of .015 inch. It has also been found that the
` total distance moved by the stylus 24 should be approxl-
mately .030 of an lnch so that the stylus ls ln ~ree flight
~or approximately .015 lnch. Accordingly, the clearance
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between the bottom of the prlnt head and the print medium
should be set at approximately .030 inch.
While the invention has been particularly shown
and described with reference to a preferred embodiment
thereof, it will be understood by those skilled in the art
that various changes in the form and detail may be made
therein without departing from the spirit and scope of the
invention.
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