Arranging structure of print wire driving units utilized in a dot impact print head

An arranging structure of print wire driving units in print head utilized in a shuttle printer is disclosed. In such structure, a plurality of head units U each of which comprises the row R1 and the row R2 of the print wire driving units 10a, 10b, are arranged in the print head H1. The rows 10a, 10b are positioned at both sides (left and right sides) in the print head H1 with reference to a line passing through the wire guide plate 22. Here, the first driving unit 10a has a construction in which the arm 12a is supported by the plate springs S in a direction vertical to a longitudinal direction of the frame F in the unit 10a and the print wire 14a is fixed to the top portion of the arm 12a so that it is extended to the longitudinal direction of the frame F in the unit 10a. And the second print wire driving unit 10 b has s construction in which the arm 12b is supported by the plate springs S in the same direction as the longitudinal direction of the frame F in the unit 10b and the print wire 14b is fixed to the top portion of the arm 12b so that it is extended to a direction vertical to the longitudinal direction of the frame F in the unit 10b. In both rows R1, R2, the first driving units 10a and the second driving units 10b are alternately arranged each other with right angle, thus, the arms 12a, 12b are arranged with parallel relationship therebetween and the print wires 14a, 14b are arrayed in a straight line on the wire guide plate 22.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to an arranging structure of print wire 
driving units in a print head installed in a dot printer, particularly in 
a shuttle printer. 
2. Description of the Related Art 
A conventional shuttle printer is disclosed in U.S. Pat. No. 3,941,051. The 
shuttle printer includes a print head having a plurality of hammers which 
are arranged in a direction along a longitudinal direction of a platen. 
The plurality of hammers are individually moved between an impact position 
and a retract position by a plurality of electromagnetic actuators. 
SUMMARY OF THE INVENTION 
An inventor of the present invention developed a shuttle printer by using a 
print head having a plurality of print wire driving units each of which 
has a piezoelectric actuator. The piezoelectric actuator has advantages in 
comparison with the electromagnetic actuator. For example, the 
piezoelectric actuator can respond more quickly to a driving signal than 
the electromagnetic actuator. Further, the piezoelectric actuator 
generates less heat than the electromagnetic actuator. Consequently, the 
shuttle printer utilizing the piezoelectric actuator is capable of 
performing high speed printing with less heat generated. 
Here, a structure of the print wire driving unit A will be described 
according to FIG. 15. This driving unit A essentially comprises a 
well-known piezoelectric driving unit in which a multi-layered 
piezoelectric member 110 is utilized. The piezoelectric member 110 is 
supported in a frame 112 and, to an upper end of the piezoelectric member 
110, a movable member 114 is fixed. And a plate spring 116 is attached to 
a side surface of the movable member 114, further, one more plate spring 
118 is fixed to the frame 112 in superposing with the plate spring 116. 
And to upper ends of both the plate springs 116, 118, a retaining member 
120 is attached. An arm 122 to a top end portion of which a base portion 
of a print wire 124 is fixed, is horizontally extended as shown in FIG. 
15. A top end portion of the print wire 124 is opposed to a print sheet 
128 as a printing medium supported on a platen 126, through a print ribbon 
130 arranged between the print sheet 128 and the top end portion of the 
print wire 124. 
Accordingly, when the piezoelectric member 110 is extended by energizing 
through power source, the plate spring 116 is slidden relatively to the 
plate spring 118 to a positive direction, thereby, the retaining member 
120 is rotated to counterclockwise direction in FIG. 15. As a result, the 
print wire 124 is advanced to the print sheet 128 since the arm 122 is 
rotated to counterclockwise direction with the retaining member 120 and a 
printing dot is formed on the print sheet 128 by depressing the the print 
ribbon 130 on the print sheet 128 through the top end portion of the print 
wire 124. 
On the contrary, when the piezoelectric member 110 is contracted from the 
extended state by removing electric energy therefrom, the retaining member 
120 is rotated to clockwise direction, as a result, the print wire 124 is 
returned to retracted position. And when the print wire 124 returns to the 
retracted position, it is contacted with a rubber stopper 132 which is 
adhered to the frame 112 at behind side of the arm 122 and limits the 
retracted position of the print wire 124. 
Here, a temperature compensating member 134 is fixed to lower end of the 
piezoelectric member 110. This temperature compensating member 134 
depresses the piezoelectric member upward to the movable member 114 
through a pin 136 accommodated in the frame 112. The temperature 
compensating member 134 is necessary to avoid a case that the 
piezoelectric member 110 cannot be extended to the proper printing 
position due to a residual stress remained in the piezoelectric member 110 
since the residual stress corresponding to the temperature of the 
piezoelectric member 110 is apt to be remained therein if the electric 
energy (voltage) is completely removed therefrom. 
In order to arrange a plurality of the print wires in the print head of the 
shuttle printer, the above constructed driving units A are arranged 
parallel therein. For instance, each of the driving units A is mutually 
arranged in side by side relationship. 
However, in such parallel arranging structure, it is necessary to arrange 
the driving units A with sufficient distance between the driving units A 
so that the print wires 124 does not contact with the neighboring driving 
units A while driving of the print wires 124. In order to dissolve this 
problem, it is necessary to widen the distance between the neighboring 
print wires 124 in excess of the thickness of the driving unit A, 
therefore, accumulating or densifying of the print wires 124 in the print 
head cannot be accomplished. 
Especially in the shuttle printer, moving distance of the print head 
between the neighboring print wires 124 becomes unnecessarily long 
distance, thus, it is prevented printing speed of the print head from 
being made more faster, since the long distance must be formed between the 
print wires 124 in the parallel arranging structure. 
Accordingly, it is an object of the present invention to overcome the above 
mentioned problems and to provide an arranging structure of print wire 
driving units utilized in a dot impact print head to accomplish 
accumulating or densifying of the print wires, thereby to make printing 
speed by the print head more faster, the arranging structure comprising: 
a plurality of first print wire driving units each having a first unit 
frame; a first driving means mounted in said first unit frame; a first arm 
supported to said first driving means at a first predetermined angle, said 
first arm being thinner than said first unit frame; and a first print wire 
having a rear portion affixed to said first arm and extending at an angle 
of approximately 90.degree. thereto, and a front portion adapted to extend 
through said print head front surface to effect printing; 
a plurality of second print wire driving units each having a second unit 
frame, the thickness of said second unit frame being equal to that of said 
first unit frame; a second driving means mounted in said second unit 
frame; a second arm supported to said second driving means at a second 
predetermined angle, said second arm being thinner than said second unit 
frame; and a second print wire having a rear portion affixed to said 
second arm and extending at an angle of approximately 90.degree. thereto, 
and a front portion adapted to extend through said print head front 
surface to effect printing; 
said plurality of first print wire driving units being disposed side by 
side and said plurality of second print wire driving units being disposed 
side by side, said first and second pluralities being at an angle with 
respect to each other so that said first arms and said second arms are 
parallel and said first unit frames being offset with respect to said 
second unit frames by half the thickness of said second unit frames 
whereby said first and second print wires alternately extend in a straight 
line through said print head front surface. 
According to the present invention, accumulating or densifying of the first 
and the second print wires can be accomplished since the first and the 
second driving units are alternately arranged with the difference angle 
between the first and the second predetermined angles so that the first 
and the second arms are arranged each other with the parallel relationship 
therebetween and with the narrower distance than the predetermined 
thickness therebetween. Therefore, if the arranging structure is utilized 
in the print head of the shuttle printer, printing speed can be made more 
faster because moving distance of the print head while printing can be 
reduced.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
A detailed description of the first preferred embodiment of an arranging 
structure of print wire driving units in a dot impact print head embodying 
the present invention will be given referring to the accompanying 
drawings. 
In FIGS. 1 through 6, the first embodiment of the present invention is 
shown. Referring to FIGS. 1 and 2, a print head H1 utilized in a shuttle 
printer has a front frame 16 and two mounting frames 18, 19 positioned in 
the print head H1 with right angle to the front frame 16, both the frames 
18, 19 being parallel formed along a longitudinal direction of the print 
head H1 (see FIG. 2). And, in the front frame 16, a plurality of rectangle 
openings 20 for passing print wires 14a, 14b (later mentioned) 
therethrough are formed according to a horizontal line lying in the middle 
of the print head H1, as shown in FIG. 2. At front side of each opening 
20, a wire guide plate 22 having twenty four guide holes 24 is fixed. 
Over both a left inner side of the front frame 16 and a right side of the 
mounting frame 18, a row R1 comprising a plurality of the first print wire 
driving units 10a and the second print wire driving units 10b is arranged 
(arranging structure thereof will be described later). Similarly, another 
row R2 having the same structure as the row R1 is arranged over a right 
inner side of the front frame 16 and a left side of the mounting frame 19. 
Here, the rows R1, R2 constitute a head unit U and a plurality of the head 
units U (twelve units U are arranged in this first embodiment) are 
arranged in the print head HI as shown in FIG. 2. 
Next, the arranging structure of the rows R1, R2 will be described 
according to FIGS. 3 through 6. 
At first, the first print wire driving unit 10a is explained referring to 
FIG. 4. The first print wire driving unit 10a has an essentially same 
structure of the driving unit shown in FIG. 15, thus, detailed description 
thereof is omitted here. That is to say, it should be noted that an arm 
12a is supported to plate springs S in a direction vertical to a 
longitudinal direction of frame F of the driving unit 10a (that is, the 
arm 12a is supported to the plate springs S with 90 degrees) and a print 
wire 14a is fixed to the top portion of the arm 12a so that the print wire 
14a is extended parallel to the longitudinal direction of the frame F of 
the driving unit 10a. Further, in the print wire driving unit 10a, a 
buffer member 26 is attached to behind side of the arm 12a against to a 
stopper 27 elongated over upper surfaces of the driving units 10a (see 
FIG. 3). 
The second print wire driving unit 10b is shown in FIG. 5. This type of the 
driving unit is different from the first driving unit 10a at a point that 
an arm 12b is supported to plate springs S in the same direction as the 
longitudinal direction of the frame F of the driving unit 10b (that is, 
the arm 12b is supported to the plate springs S with 0 degree) and a print 
wire 14b is fixed to the top portion of the arm 12b so that the print wire 
14b is extended vertically to the longitudinal direction of the frame F of 
the driving unit 10b. 
The first print wire driving units 10a and the second print wire driving 
units 10b are mutually arranged as shown in FIG. 3. In FIG. 3, the first 
driving units 10a are vertically arranged each other with substantial side 
by side relationship. Here, though, in fact, twelve units 10a are 
arranged, only four units 10a are shown in FIG. 3 for convenience. And the 
second driving units 10b are horizontally arranged each other with 
substantial side by side relationship so that each second driving unit 10b 
is deviated in a thickness direction of the frame F in the first driving 
unit 10a with a half distance of the thickness of the frame F and the arms 
12b are position between the arms 12a of the first units 10a. Similarly to 
the above, though, in fact, twelve units 10b are arranged, only three 
units 10b are shown in FIG. 3 for convenience. Here, the arms 12a, 12b 
does not interfere each other since thickness of the arms 12a , 12b is 
sufficiently thinner than the thickness of the frame F in the driving 
units 10a, 10b. And the thickness of the frame F in the first driving unit 
10a is as same as that of the frame F in the second driving unit 10b. 
Therefore, both the first and the second driving units 10a, 10b are 
alternately arranged each other with right angle. And each first driving 
unit 10a is fixed to the right side of the mounting frame 18 and each 
second driving unit 10b is fixed to the left inner side of the front frame 
16 as shown in FIG. 1. As a result, the row R1 is arranged over the 
mounting frame 18 and the front frame 16. 
In the row R1, accordingly, the arm 12a in the driving unit 10a and the arm 
12b in the driving unit 10b are parallel arranged each other as shown in 
FIGS. 3 and 6, as a result, the print wire 14a of the arm 12a and the 
print wire 14b of the arm 12b are mutually directed to the same direction 
on a straight line so that the top portions of the print wires 14a, 14b 
are put into the guide holes 24 of the guide plate 22. Therefore, a wire 
array constructed by the top portions of the print wires 14a, 14b is 
formed on the front surface of the guide plate 22 as shown in FIG. 2. 
Similarly to the row R1, another row R2 having the same structure as the 
row R1 is arranged symmetrically on the opposite (right) side of the row 
R1 in taking a vertical line passing through the center of the opening 20 
as the symmetrical standard line in FIG. 1. That is to say, in the row R2, 
the second driving unit 10b is fixed to the right inner side of the front 
frame 16 and the first driving unit 10a is fixed to the left side of the 
mounting frame 19. And the print wires 14a, 14b of the arms 12a, 12b are 
mutually directed to the same direction on a straight line so that the top 
portions of the print wires 14a, 14b are put into the guide holes 24 of 
the guide plate 22. Accordingly, another wire array constructed by the top 
portions of the print wires 14a, 14b in the row R2 is formed on the front 
surface of the guide plate 22 as shown in FIG. 2. As a result, two wire 
arrays are parallel formed on the front surface of the guide plate 22. 
Clearly from the above arranging structure according to the first 
embodiment, it can be prevented both the driving units 10a and 10b from 
interfering the print wires 14a and 14b adjoining each other, though 
accumulating or densifying of the print wires cannot be realized in the 
parallel arranging structure of the driving units due to relatively wide 
width in the piezoelectric member or the plate spring. Accordingly, the 
distance between the print wires 14a, 14b adjoining each other can be 
reduced to a half of the distance in comparison with the parallel 
arranging structure in which each driving unit is simply arranged with 
side by side relationship, as understood from FIG. 3. Therefore, 
forty-eight print wires 14a, 14b can be arranged in the head unit U with 
same size as the parallel head unit in which only twenty-four print wires 
are arranged, as a result, printing density becomes twice comparing with 
the parallel head unit. 
On the other hand, for instance, on case that the number of the print wires 
arranged in the print head H1 is same, the print wires 14a, 14b can be 
arranged with high density (twice density) in the wire guide plate 22 as 
shown in FIG. 16, according to the first embodiment mentioned above, in 
comparison with the parallel arranging structure in which the print wires 
124 are arranged with low density (half density of the arranging structure 
shown in FIG. 16) in the print head. 
Further, according to the above arranging structure, the print wires 14a, 
14b can be shortened as shown in FIG. 1, thus, the print wires 14a, 14b 
can be easily guided by only the wire guide plate 22. Here, the print head 
H1 is reciprocally moved according to an arrow direction shown in FIG. 2 
and printing is conducted. 
Next, the second embodiment of the present invention will be described 
hereinafter referring to FIGS. 7 through 9. In FIG. 7, a print head H2 
comprises two rows R3, R4, each having third and fourth print wire driving 
units 30a, 30b. 
Here, the third driving unit 30a and the fourth driving unit 30b will now 
be described according to FIGS. 8 and 9. In FIG. 8, the third driving unit 
30a has an essentially same structure of the first and the second driving 
units 10a, 10b. Different point from the first and the second driving 
units 10a, 10b is that fixing angle of an arm 32a to plate springs S is 
set to 45 degrees around the clockwise direction (see FIG. 8) with 
reference to a line extending through longitudinal direction of frame F in 
the third driving unit 30a. And a buffer member 35 is attached to behind 
side of the arm 32a. 
On the other hand, the fourth driving unit 30b has an essentially same 
structure of the third driving unit 30a and different point from the third 
driving unit 30a is that fixing angle of an arm 32b to plate springs S is 
set to 45 degrees around the counterclockwise direction (see FIG. 9) with 
reference to a line extending through longitudinal direction of frame F in 
the fourth driving unit 30b. And a buffer member 36 is attached to behind 
side of the arm 32b. 
Again referring to FIG. 7, explanation of the print head H2 will be 
continued hereinafter. In the row R3, the third driving unit 30a and the 
fourth driving unit 30b are arranged each other with right angle in the 
print head H2 so that both the arms 32a and 32b are alternately positioned 
with parallel relationship therebetween. That is to say, the fourth 
driving units 30b are alternately arranged to downward direction with 45 
degrees with reference to a horizontal line and the third driving units 
30a are alternately arranged between the fourth driving units 30b to 
upward direction with 45 degrees with reference to the horizontal line, as 
shown in FIG. 7. As a result, print wires 34a, 34b, each being fixed to 
the top portions of the arms 32a, 32b, respectively, are mutually directed 
to the same direction on a straight line so that the top portions of the 
print wires 34a, 34b are put into guide holes 37 of wire guide plate 38. 
Similarly to the row R3, another row R4 having the same structure as the 
row R3 is arranged symmetrically on the opposite (right) side of the row 
R3 in taking a vertical line passing through the center of the guide plate 
38 as the symmetrical standard line. 
Thus, two wire arrays constructed by the top portions of the print wires 
34a, 34b are formed on the front surface of the guide plate 38. 
Here, in FIG. 7, a stopper member 39 is positioned behind both the buffer 
members 35, 36 and a plurality of support guide plates for guiding the 
print wires 34a, 34b and the wire guide plate 38 are positioned in a head 
case C. 
According to the above arranging structure of the second embodiment, the 
print wires 34a, 34b can be arranged with twice density in comparison with 
the parallel print head, similarly to the first embodiment mentioned 
above. And further, space surrounding the print head H2 can be efficiently 
utilized because it is not prevented the fourth driving units 30b from 
being arranged to downward direction with 45 degrees if a round platen 
(roller platen) P is utilized as shown in FIG. 7. 
Next, the third embodiment of the present invention will be described 
hereinafter referring to FIG. 10. In FIG. 10, a print head H3 comprises a 
construction in which a new row R5 (later mentioned) is added to the print 
head H2 having the row R3 and the row R4 mentioned above. The row R5 in 
which a plurality of print wire driving units 40 (each is same as the 
first driving unit 10a) are arranged so that top portion of each arm 42 is 
alternately arranged with opposing relationship, is arranged to a position 
where the stopper member 39 is positioned in the print head H2. According 
to the arranging structure of the third embodiment, three arrays of the 
print wires 34a, 34b and 44 are formed on the front surface of wire guide 
plate 38. Clearly understood from FIG. 10, since each driving unit 30a, 
30b and 40 does not interfere each other, distance between two print wires 
in each array can be reduced to half in comparison with the parallel 
arranging structure in which each driving unit is simply arranged with 
side by side relationship. 
Finally, the fourth embodiment of the present invention will be described 
hereinafter referring to FIGS. 11 through 14. In a print head H4, two rows 
R6 and R7 are arranged at both sides with reference to a symmetrical line 
passing a wire guide plate 51 mounted at the center of the front surface 
of the print head H4. 
Here, each of the row R6 and the row R7 has the same construction, thus, 
the row R6 will be representatively described according to FIGS. 12 
through 14. In the row R6, a plurality of print wire driving units 50b, 
each having the same construction as the second driving unit 10b utilized 
in the first embodiment mentioned above, are arranged each other with side 
by side relationship. 
And further, a plurality of print wire driving units 50a, each also having 
the same construction as the second driving unit 10b, are arranged on the 
driving units 50b in superposing each other with up and down relationship 
therebetween, so that each driving unit 50a is slightly deviated from each 
of the driving unit 50b with a half distance of the thickness of the 
driving unit 50b as shown in FIGS. 12 and 14. 
As a result, each upper arm 52a of the driving unit 50a is positioned 
between lower arms 52b of the driving units 50b while the upper arms 52a 
are separated from the lower arms 52b with a predetermined distance 
therebetween. Further, based on the above relationship between the arms 
52a and 52b, print wires 54a of the driving units 50a are arranged between 
print wires 54b of the driving units 50b so that top portions of the print 
wires 54a, 54b are arrayed in a straight line on the wire guide plate 51. 
Here, the print wires 54b are made longer than the print wires 54a so as 
to retain the same level as the print wires 54a. 
Additionally, the row R7 has the same construction as the row R6 mentioned 
above, therefore, two arrays of the print wires 54a, 54b are formed on the 
wire guide plate 51. 
According to the fourth embodiment mentioned above, distance between the 
print wire 54a and 54b in the array can be reduced to half in comparison 
with the parallel arranging structure in which each driving unit is simply 
arranged with side by side relationship. Therefore, printing density 
becomes twice comparing with the parallel head unit. 
Further, in comparison with the first embodiment in which the driving units 
10a, 10b having different construction from each other are utilized, both 
the driving units 50a, 50b can be driven based on the same driving 
condition since they have the same construction each other. 
While the invention has been particularly shown and described with 
reference to preferred embodiments thereof, it will be understood by those 
skilled in the art that the foregoing and other changed in form and 
details can be made therein without departing from the spirit and scope of 
the invention. For instance, it is conceivable a modification in which an 
additional driving unit to the driving units 50a, 50b in the fourth 
embodiment is arranged in three steps with up and down relationship so 
that the additional driving unit is deviated from both the driving units 
50a, 50b by 1/3 distance of the thickness thereof. In such modification, 
printing density becomes three times in comparison with the parallel 
arranging structure. 
And further, it is conceivable a modification in which top portions of the 
print wires are arranged into one array on the wire guide plate, though 
two arrays formed by the top portions of the print wires are arranged on 
the wire guide plate in the above embodiments.