Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~Z:39l;;~8
IMPROYED DOT MATRIX PRINT HEAD GI~AOT-173
The present invention relates to dot
matrix printers and, in particular, a
shuttle-type dot matrix print head with increased
speed and improved graphic capability.
'I 3~
A dot matrix printer is an apparatus
which prints a plurality of closely spaced dots,
at high speed, at selected locations on a paper
stri p to form 1 etters numeral s, or other
5 intelligible symbols thereon. The dots are
formed by causing contact between the paper and
an ink impregnated surface at desired locations
by selectively electromagnetically displacing
elongated print wires mounted within the print
head.
Certain types of known dot matrix
print heads consist of a plurality ox selectively
electrically energizable solenoids, each ox which
has a separate print wire extending therefrom.
The impact ends of the print wires are retained
in a fixed position with respect to each other
by a stationary wire bearing which forms a part
of the head. The wire bearing has a plurality
of closely spaced openings arranged in a
matrix array. Each opening receives the impact
end of a different print wire. Energization of a
selected solenoid results in the print wire
associated therewith being displacPd~ such
that the impact end thereof extends beyond the
surface ox the bearing and causes contact
between the paper and the ink î~pregnated
surface. The paper is moved relative to the
wire bearing in a first direction such that
printing of symbols can take place along a line
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and in a second direction such that different
lines can be printed.
Such heads are bulky and heavy, as
well as being complex in nature and, therefore9
relatively expensive to manufacture and maintain.
Since the solenoids have a relatively large
d~ameter~ the solenoids require a space much
larger than the dimensions of the matrix array
of the print wire impact ends. Thus, complicated
arrangements of the solenoids are necessary in
order for a sufficlent number to be incorporated
into the head to provide the required number of
print wires.
For this reason, the solenoids are
often arranged in groups or banks at different
levels or in arcuate arrays. When arranged
at different levels, each gPOUp of solenoids
must be provided with print wires of different
length depending upon how far the group is
spaced from the wore bearing. When arranged
in an arcuate array, the print wires must be
curved to various degrees, according to the
placement of each solenoid from the center line
of the array. In this instance, rigid lubricated
sheaths surrounding each print wire so as to
guide the movement thereof, may be required in
order to maintain the proper wire curvature and
prevent the destruction of the fragile print
wires.
In order to increase the speed of the
printer, some printers have been devised where
the paper is held stationary as the head is moved
to traverse the paper to print each line of
symbols An increase in print speed is possible
under such circumstances because the platen upon
which the paper is situated is quite massive and,
thus, can be moved only relatively slowly. The
solenoicl carrying support may be moved somewhat
more easily than the platen. Actuation of the
solenoids can take place quite rapidly.
However, rapld movement of the solenoid
carrying support is also quite difficult because
it too has substantial mass and therefore high
inertia. Thus, other types of actuators, having
substantially less mass than solenoids, have been
employed in an attempt to reduce the mass of the
moving support. See for example, U.S. Patent No.
3,973,661, issued August 10, 1976 to DeBoo, which
discloses a wire matrix printer employing spring
reed type actuators on a movabl e support. However9
DeBoo's support is still too massive for the rapid
movement required or high speed printing.
Another attempt to solve this problem
is the solenoid printer disclosed in U.S. Patent
No. 4~0539040, issued October 11, 1977 to
McGourty. In that printer, solenoids are mounted
in an arcuate array on a supportO The wire
bearing is also mounted on the support. Instead
of causing the entire support to traverse the
3~2~ ~3
paper, the support is pivotly mounted with respect
to the base of the head. The pi votal movement of
the support causes the wore bearing and, thus
the impact ends of the print wires, to move in an
S arc adjacent the plane of the paper, to print each
line of symbols.
The McGourty printer was an improvement
over the concept of translating the entire
solenoid head, but still required for pivoting
of a large mass. Thus7 while it reduced the
problem of inert1a, it dld not solve the problem
entirely because the inertia of the pivoting head
still reduced the speed of the printer to an
unacceptable extent. In addition moving the
wire bearing in an arc meant that the impact
ends of certain print wires were located further
from the plane of the paper than others at the
extremes of the pivotal movement.
In order to overcome the problems
associated with the solenoid-~ype print head,
including the weight, bulk, complexity, and
cost of the solenoids, solenoid actuators have,
in some instances, been replaoed with
extremely thin, coil carrying hammer-type
actuators. Hammers of this type are so thin
that a plurality of closely spaced,
paral lel ly situated hammers can be mounted
3 6
between a single pair of stationary magnets.
Each hammer comprises a thin planar frame
having a recess into which a flat coil is
received. The coil carrying portion is suspended
from a support, in cantilever fashion, by an
elongated flexible portion, such that it is
situated in a substantially unlform magnetic
field created between the permanent magnets.
The leads of each coil are connected
to the circuitry designed to electrically
energize the coils of selected hammers. A
print wire is mounted to and extends from the
frame and is displaceable therewith. When
the hammer is actuated by electrically
energizing the coll, sufficient electromagnetic
force develops to displace the hammer from its
original position such that the impact end of
the print wire is moved to cause a dot to be
imprinted on the paper.
Print hammers of this type are
described in detail in U.S. Patent No. 4,349~283
issued September 14, 1982 to Thomas P. Sapitowioz
and Robert A. Meloni, and which is assigned to
the assignee hereof. The reader is referred
Jo that patent for more detailed information
concerning the structure and function of hammers
of the type here under discussion.
While great advantages are achieved
through the use of the hammer actuators of the
type disclosed on the above cited patent, over
solenoid-type actuators even further increases
in speed can be obtained by combining the use of
hammer-type actuators with the idea of reducing
the mass, and thus the inertia, of the part which
traverses the paper to scan each l;ne. Moreover,
if each print wire can be made to print a
plurality of dots per line, enhanced graphic
capability can be obtained such that a wider
variety of different types of symbols, such as
logosS can be printed.
In general, these objectives are
achieved in the present invention by keeping the
support upon which the hammer actuators are
mounted stationary and by moving only a very low
inertia wire bearing, which carries the impact
ends of the print wires, to traverse the paper.
Since each hammer can be actuated a number ox
different times during each traversing movement
of the print wire impact end positioning member,
each print wire can print a plurality of dots per
line and the spacing between the imprinted dots
can be varied.
The print wire impact end posltioning
member can be made of material having a very
low mass and can be at least partially hollow,
268
such that the inertia thereof is very small,
Thus, this member can be moved and stopped very
rapidly such that increased print speed
results.
Since the print wîre impact end
positioning member need be moved only a
relatively small distance to scan each line,
the maximum deviation ox the impact end ox the
print wire from its normal position and hence
the curvature of the print wire from its
normal straight condition, is similarly
quite small.
It should be appreciated that only
the low inertia impact end positioning member
is moved as each line of the paper is scanned.
The hammer actuators themselves are not moved
in a plane parallel to the paper. Thus, the
hammer bodies, and particularly the permanent
magnets associated with the hammers, are not
moved as scanning takes place. Therefore,
movement is confined to a very low inertia
part, such that it can take place very rapidly
and with great accuracy.
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The movement and position of the reciprocating
low mass positioning member must be achieved with sub-
stantial accuracy. Further, at certain times, the movement
of the positioning member must cease so as to permit
indexing of the paper relative to the print head such
that the next line can be scanned. In the present
invention, these objectives are obtained through the use
of a simple rotatable mechanism which controls the movement
of the positioning member.
It is, therefore, a prime object of the present
invention to provide an improved dot matrix print head
capable of printing at increased speeds.
The invention provides a head for printing a
dot on a paper comprising a support, a print wire having
an impact end, an actuator operably connected to said
support, active on said print wire, and effective, when
actuated, to move said impact end of said print wire to-
wards the paper, means adapted -to engage said print wire
beyond said actuator and towards said paper, for position-
ing same relative to the paper, and means for moving said
positioning means relative to said support, said position-
ing means comprising a solid body portion having first and
second surfaces and a generally cylindrical passageway
extending therebetween, and a hollow portion extending
between said body portion and said support for movably
mounting said body portion on said support with said
second surface spaced therefrom, said passageway having
an internal diameter greater than the diameter of said
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print wire to permit lateral movement of said print wire
relative to said second surface as said positloning means
is moved relative to said support, said passageway termin-
ating proximate said first surface of said body portion in
an impact end receiving opening with a diameter slightly
greater than the diameter of said print wire so as to prevent
substantial relative lateral movement between said impact end
and said Eirst surface of said body portion.
The disclosed dot matrix print head has enhanced
graphic capability. Each electromagnetically actuatable
hammer can be used to print a dot in a plurality of different
locations on the paper. The location of the impact end of
each of the various print wires, with respect to the paper,
is varied through the use of the low inertia, reciprocatable
positioning member. The dot matrix print head includes simple
means for accurately moving the positioning member relative
to the paper, and is comprised of a relatively small number
of simple and inexpensive parts which operate together re-
liably for a long useful life with a minimum of maintenance.
The dot matrix print head comprises a support
having a surface with an opening and a hammer having a print
wire extending therefrom and through the surface opening.
The hammer is mounted on the support for movement relative
thereto, when actuated. Means, movable relative to the sup-
port surface, are provided for positioning the impact end
of the print wire. Means are provided for moving the position-
ing means relative to the support surface, through a given
range.
Actuation ox the hammer causes
movement of the impact end of the print wire
extending therefrom in a first given direction
towards the paper The positioning means is
movable relative to the support surface on a
second given direction (parallel to the paper).
Thus, the directions ox movement are substantially
perpendicular to each other.
An elongated "T"-shaped protrusion or
key forms a part of the support surface. The
positioning means includes a similarly shaped
channel or keyway into which the protrusion is
movably received. The protrusion is elongated
along the surface in the direction of movement
of the positioning member. The channel and
protrusion cooperate to form a means for guiding
the movement of the positioning means.
The means for moving the positioning
means relative to the support surface comprises
a recess associated with the positioning means,
a protrusion adapted to be received within the
recess, and means or moving the protrusion.
The protrusion moving means preferably comprises
a substantially cylindrical member having a
surface and a means for rotating the cylindrical
member. The protrusion preferably comprises a
track annularly disposed on the member surface
and adapted to be received within the recess.
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12
The locatinn of the trask varies
relative to a central position on the cylindrical
member. In particular, the location of the
traek relative to the central position varies,
S within a given range3 in a sinesoidal-like
manner The track i s at a fi rst extreme of
its range relative to the central position
along one portion of the member surface and at
a second extreme of its range relative to the
central position along a second portion of the
member surface. The portions of the track
located at the extreme locations relative to the
central position each span an extended portion of
the surface of the cylindrical member. When
these track port;ons are situated within the
positioning member recess, rotation of the
cylindrical member will not cause movement of
the positioning member.
Thus, each time the cylindr~oal
member is rotated through 360 the positiDning
member will be located at one extreme position
relative to its "home" position for a short
timez move continuously prom the first extreme
position through the "home" position to the
other extreme positionS and will remain at the
other extreme position for a short time. The
positioning member will then move back through
the "home" position to the first extreme
position. The positioning member will therefore
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"dwell" for a brief period at each extreme of
its range. During these "dwell" periods, the
paper is indexed with respect to the print head
such that -the next line can be printed.
The recess associated wi-th the
positioning means is defined between first and
second spaced members mounted thereto.
Preferably, the first and second spaced members
are rota-tably mounted on the positioning means
and have a substantially cylindrical configuration.
To these and to such other objects
which may hereinafter appear, the present
invention relates to an improved dot matrix
print head as described in detail in the following
specification and recited in the annexed claims,
taken together with -the accompanying drawings,
wherein like numerals refer -to like parts and
in which:
Figure 1 is an exploded isometric view of the
improved dot matrix print head of the present
invention;
Figure 2 is a side cross-sectional view
showing the hammer and support of the improved
dot matrix print head of the present invention;
Figure 3 is a side view of the improved
dot matrix print head of the present invention;
,~
3~6~ 713~346
Figure 4 is a top view oE the print head
illustrated in Figure 3;
Figure 5 is a rear view of the print head
illustrated in Figure 3;
Figure 6 is a Eragmentary cross-sectional
view taken along line 6-6 of Figure 2; and
Fig. 7 is a fragmentary cross-sectional
view taken along line 7-7 of Fig. 2, showing
the displacemenk of the movable member relative
to the stationary frame.
As shown in Figs. 1 and 2, the present
invention relates to an improved dot matr;x
print head which includes a stationary support,
generally designated A, into which a plurality
of very thin hammer-type actuators, generally
designated B, (only one of which is shown) and a
pair of permanent magnets, generally designated
C, (only one of which is shown) are mounted.
Each of the hammers B carries a print wire
which extends through a different one of a
plurality of openings on the surface of support
A and into a positioning member, generally
designated D, which engages the impact end
thereof, Positioning member D is reciprocated
relative to the surface of support A by a moving
means generally designated E.
As positioning member D is moved
relative to support A by means E, the impact end
of each of the print wires is, likewise; moved
relative to the paper surface to scan same. A
selected hammer can be actuated to print a dot at
any one of a plurality of different locations on
each line on the paper as member D is moved.
Actuation of the various print wires is achieved
through the use of conventisnal circuitry, not shown.
~.Z3~ 3~3
16
Support A comprises an upper surface
10~ a front wall 12~ and a bottom wall 14, which
join to partially define an enclosure with an
open rear surface. ~Jithin this enclosure, a
plurality of very thin hammer actuators B are
located. Hammers B are situated in parallel,
closely spaced relationship, between a pair of
permanent magnets C, with the coil carrying
portions thereof situated in a relatively
uniform magnetic field created by the magnets.
Each of the hammers B includes a
substantially rectangular frame-like portion 16
having a recess 18 therein, also substantially
rectangular in configuration A flatJ multi-turn
coil 20 is adapted to be received within recess
18 of frame portion 16. Coil 20 also has a
central opening or recess 22 therein. Frame-like
portion 16 comprises the coil carrying portion
of hammer B.
Extending from portion 16 is a flexible
elongated portion 24, adapted to mount the coil
carrying portion 16 of the hammer to support A.
Mounting portion 24 has an elongated recess 26
therein adapted to receive the leads of coil 20,
such that same can be connected to the hammer
energizing circuitry (not shown).
Each hammer has a b;furicated part 25
with a circular central opening. Part 25
extends from the rear of mounting portion 24
in a generally perpendicular direction thereto.
An elongated, shaft 279 fixedly mounted
between openings 28 in the downwardly extending
spaced rear portions of surface 10 of support
A, is received within the opening in part 25
such that each hammer us mounted in cantilever
fashion to support A.
Affixed to either side of coil carrying
portion 16 is a heat dissipating member 30, 32
which serves to retain coil 20 within recess 18,
as well as dissipated heat from the coil and,
at the same time, to protect the coil and the
sides of the coil carrying portion 16 from wear
should the hammer inadvertently contact an
adjacent hammer during displacement. Heat
dissipating member 32 ls provided with an
elongated extension 34 which encloses recess
26 so as to protect the fragile leads of coil
20.
On the bottom of coil-carrying portion
16 is a stop member 36 which limits the recoil
movement of the hammer in eooperation with
bottom surface 14 of support A. Extending from
the top surface of coil carrying portion 16, in
alignment with stop 36, is an elongated element
plat~eYl~ol
68
38 to wh;ch a print wire 40 is mounted. Print
wise 40 extends upwardly through support A and
through member D, such that the impact end
thereof is normally coplanar with surface 42 of
S member D.
Hammers B are selected for actuation
by conventional energizing circuitry (not shown.
When selected for actuation, the leads to coil
20 are connected to a power source such that
current flows through coil 20 of the selected
hammer. Since the hammer is situated within a
magnetic field created by magnets C, the flow
of current through the coil results in an
electro-motive force which will abruptly displace
the coil carrying portion 16 of the hammer
from its rest position towards surface 10 of
support A, against the resiliency of mounting
portion 24. This causes the impact end of print
wire 40 to extend a short distance beyond surface
42 of member D such that it causes contact
between the paper and an ink impregnated surface
to print a dot on the paper. When the energization
of the coil terminates, the resiliency of
mounting portion 24 fill cause the coil carrying
portion 16 to move back towards its rest
position, away from surface 10 of support A,
until stop member 36 is again adjacent bottom
surface 14 of support A.
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19
Fixedly mounted to the top surface 10
is a guide member 44 which forms a part of support
A Member 44 includes a relatively wide base 46
which is provided with four openings 48, adapted to
align with openings 50 in surface 103 such that
guide member 44 can be mounted to surface 10 by
screws or the like. Extending from base 46 of
guide member 44 is a rectangular part 52~ which is
substantially narrower than base 46. Located
on top of part 52 is mounted a "T"-shaped
keyway 54.
The internal structure of member 44
can best be appreciated by a comparison of Figs.
2 and 6. Base 46 and the lower portion of part
15 52 are provided with an elongated rectangular
opening 56 which extends along the most of the
length of guide member 44. Opening 56 in guide
member 44 aligns with opening 58 in surface 10
to provide clearance for the movement of the
print wire mounting elements 38, when the
hammers are actuated.
The upper portion of part 52 and
keyway 54 are provided with a plurality of
passageways 60~ each of which aligns with and
receives a different one of the print wires 40
from hammers B. Each of the passageways 60 has a
lower section 60a and an upper section 60b,
The lower section 60a of the passageway has a
'LZ3~268
relatively large inner diameter, substantially
larger than the outer diameter of the print
wire. The diameter of section 60a tapers down
to a much smaller diameter in section 60b~
which is equal to the diameter of the aligned
opening in surface 54, but still somewhat larger
than the outer diameter of the print wire, so
as to permit limited flexing of the print wire
relative to its straight condition.
The bottom portlon of member D has
a "T"-shaped channel 62 therein. "T"-shaped
keyway 54 is received in correspondingly shaped
channel 62 in member D such that member D can
move laterally with respect to stationary
surface A. The keyway and channel combinatlon
serve to guide the movement of member D.
Member D is made of a low mass low
A inertial material, such as r- or the like.
Thus, member D can be moved and stopped
accurately and quickly, with minimum application
of energy.
The interior structure of member D
can also be appreciated with reference to Figs.
2 and 6. Positioning member D has a relatively
large hollow chamber 64 which extends between
the upper surface 55 of keyway 54 approximately
two-thirds the length of member D. Thus, member
D is at least partially hollow reducing the
~LR1~ ~D~ is ~g~5te~O( Cl~k )
inert1a thereof even further A plurality
of passageways 66--one for each print wire--extend
from the top of chamber 64 to surface 42. Each
nf the passageways 66 includes a first section
66a which has an inner diameter which is
substantially greater than the outer diameter
of the print wire. At the top of each
passageway section 66a9 the diameter of the
passageway abruptly tapers to form a second
passageway section 66b which has an inner diameter
whlch is only slightly greater than the diameter
of print wire 40. Section 66b engages the
impact end of the print wlre 44 in a manner
which permits little, iF any lateral movement
of the impact end relative to surface ~2.
Each section 66b terminates in a different
opening 68 on the surPace 42 of member D.
Openings 68 are preferably spaced approximately
lJ8 inch apart.
The impact end of each print wire 40
is thus held within a different one of the
openings 68 in surface 42 and is normally
coplanar with surface 420 However when the
hammer from which the print wire extends is
actuated the impact end of the print wire
will abruptly protrude beyond surface 42. The
position of the impact end of the print wire
22
of an actuated hammer relative to the paper,
which is defined by the position of member D
relative to support A, will determine the location
on the paper of the dot imprinted by the actuation
of the hammer.
Member D will be moved relative to
support A in a reciprocating motion so as to
move the impact ends of the print w7res relative
to the paperO Figs r 6 and 7 illustrate the
movement of member D. jig. 6 shows member D in
its "home" or center position within its range
of movement with respect to support A. In this
position, each of the print w;res 40 is substan-
tially straight. Member D is movable along
keyway 54 a short distance to the left and to
the right of the "home" pos;tion. In Fig. 7,
member D is shown in solid at the extreme left
position in its range, in phantom at the
extreme right position within its range.
As will be appreciated from Fig 7,
when member D is moved relative to its "home"
position, the portion of each of the print
wires between surface 55 and surface 42 will
flex or curve slightly. However, this flexing
or curvature will be relatively minor because
the displacement of member D in either direction
from its "home" position is smallO Due to the
lZ3126B
23
minor flexing of the print wires, the impact ends
thereof can imprint dots on different locations
on the paper, in accordance with the posit;on
of member D when the hammers are actuated.
Neither the movement of member D nor the flexing
or curving ox the print wires affect the position
of the hammers or cause any lateral movement
thereof.
Means E causes positioning member D
to "shuttle" or reciprocate withîn a given range
with respect to support member A. Means E
comprises a rotatable shaft 70 upon which is
mounted a substantially cylindrical member 72 .
Extending outwardly from the outer surface of
cylindrical member 72 is a flange or annular
track 74~ a portion of which is received within
a recess defined between a pair of spaced
rollers 76, 78. Rollers 76 and 78 are rotatably
mounted on the surface of member D.
Track 74 is not situated entirely
;n a plane perpendicular to and bisecting the
surface of cylindrical member 72; but, ;nstead~
is skewed with respest thereto If the distance
between the track and the plane were graphed
around the surface of the member, a sinesoidal-like
curve with extended linear top and bottom
portions would result. Thus, one section of the
track lies to one side of the plane and another
~1~3~6~3
24
section of the track lies on the other side of
the plane. As shaft 70 is rotated and track 74
moves through the recess between members 76 and
7~, member D will follow the position of the
portion of the track situated between members
76 and 78 and "shuttle" back and forth with
respect to support A. While this motion is
continuous between one extreme of the path of
movement and the other, the movement us
interrupted at each extreme to permit member D
to stop or "dwell" for a brie period at each
extreme of its path of movement, to permit
indexing of the paper.
For example, assume that shaft 70
beglns at 0 rotation with member D at the
extreme left portion of its path of movement
as ;llustrated in solid in FigO 7. The operative
portion ox track 74 (that portion within the
recess defined between rollers 76 and 78) is at
its extreme left position with respect to a
center plane bisecting cylindrical member 72.
For the first few (eight) degrees of rotation
the operative portion of track 74 is straight and
remains at its extreme left position such that
member D will remain at its extreme left position.
Starting at 9 of rotation, khe operative portion
of track 74 begins to curYe towards the plane
and will move continuously towards the plane
until 90 of rotation where it coincides
6~3
with the plane. At this position, member D is
in the posltion shown in Fig. 6" that is, the
"home" position
Beginning at 90~ of rotation,
5 the operative portion of the track will move
continuously towards the right, until at 172,
it reaches its right limitO At this point,
member D will be in its extreme right position,
as shown in phantom in Fig. 7. Between 172
and 188, the operative portion of track 74 is
straight such that member D remains in its right-
most positionO
Beginning at 189 rotation, the
operative portion of the track will move back
15 continuously towards the central plane9 reaching
same at 270 rotation. As this occurs, member D
moves prom its extreme right position back to
its "home" position. From 270 to 352 the
operative portion of track 74 will move from
20 the central plane to its left extremity, such
that member D moves towards its left-most limit,
as illustrated in solid in Fig. 7. At 352 the
operative portion of the track has reached its
left-most limit and is straight through 360,
25 until 8 in the next rotation, when it will
reverse movement and move back towards the
central plane.
It should now be apparent that the track
has a sinusoidal curvature with extended linear
30 portions at each extreme. Thus, member D will
26
reciprocate or "shuttle" relative to surfaoe A,
while stopping or "dwelling" at each extreme of it-
movement, for a rotat10n of 16 of cylindrical
member 72. This 'Idwell" period provides sufficient
time for the paper to be moved relative to the
print head such that the next line of MY can
be printed thereon.
The rotation of shaft 70 is caused by a
motor 80 having a rotatable output shaft 82. Shaft
82 has a pulley 84 mounted thereto. Pulley 84
is connected to a pulley 86 fixed on shaft 70 by
belt 88.
Rotation of shaft 70 causes member Do
and thus the impact ends of the print wires 40, to
move back and forth with respect to the paper,
within a relatively small range. "Dwell" periods
of relatively short duration are provided at either
extreme of the range. Each of the hammers can be
actuated a plurality of different times during each
movement of member D. The timing of the actuation
and the selection of the hammers will determine
the locations of the imprinted dots, as well as
the spacing therebetween.
Positioning member D can be moved
quickly and accurately because it is composed of
low mass material and is partially hollow, such
that the inertia thereof is quite smallO The
higher mass hammers are not moved laterally.
'lL;~3~6~3
27
In addition, it should be appreciated
that while member D moves to one side or the
other of its "home" position, this movement
is relatively slight such that the curvature of
the pr;nt wire, even at the extreme posit;ons,
is quite slight Moreover the internal
structures of guide member 44 and positioning
member D are such that the print wires are
supported in such a way that the minor flexing
cannot result in damage or permanent bending of
the print wires.
While only a single preferred embodiment
of the present invention has been disclosed
herein for purposes of illustration, it is obvious
that many variations and modifications could be
made thereto. It is intended to cover all of
these variations and modifications which fall
within the scope of the present invention, as
defined by the following claims:
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