A printer mechanism is provided for adjusting the position of hammers
when the relative distance between a type character and a print
hammer is changed. The mechanism comprises a plurality of hammers
driven toward a series of type characters which are continuously
carried along the printing line to print characters on a record
sheet interposed between said print hammers and type characters.
The mechanism is designed such that said print hammers are shifted
in the printing line so that the positions of respective hammers
may be adjusted and correct printing is accomplished.
What is claimed is:
1. A hammer type printer mechanism comprising:
a belt having a multiplicity of embossed type characters thereon;
a driving pulley and driven pulley around which the belt is looped
to carry the characters along a printing line;
a plurality of printing hammers for impacting with the type characters
to print the characters on a recording medium;
leaf springs for supporting said printing hammers;
electromagnetic actuating means for striking said printing hammers
to cause said printing hammers to impact against said recording
support means for mounting said leaf springs in said printer;
means for shifting said support means in a direction parallel with
the printing line, wherein said shifting means includes:
a guide member for supporting slidably said support means;
a threaded member journaled in said guide member and threaded in
said support means so as to shift said support means when rotated,
a dial attached to said threaded member and exposed on one side
of said guide member for manual manipulation.
2. The hammer type printer mechanism of claim 1 wherein the dial
and guide member are connected by a detent mechanism which holds
the dial in one of a plurality of rotary positions, and wherein
the detent mechanism includes a hole in said dial containing a coil
spring and ball and the guide member includes a plurality of relatively
shallow holes which receive a portion of the ball therein, when
the dial is rotated to align the holes in the dial with the holes
in the guide member.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a hammer type printer, and more particularly
to a mechanism for shifting a plurality of print hammers along a
printing line so as to adjust a print timing and thereby adjust
the positions of the print hammers.
In printers known as type printers wherein a print hammer is driven
toward type characters on a print belt continuously carried along
a printing line, the adjustment of positions of the print hammers
is required every time a recording sheet is changed to a sheet of
different thickness. The reason is that if another record sheet,
different in thickness, is exchanged without adjustment of the print
hammer positions, flying time is varied whereby the relation of
the positions between each of print hammers and each of type characters
on the print belt is changed.
2. Description of the Prior Art
Heretofore, when record sheets of different thickness are exchanged,
the adjustment of the print hammers positions has been effected
by advancing or retracting the print hammers toward or from the
However conventional mechanisms for adjusting the positions of
print hammers have defects that are troublesome to adjust because
both right and left side ends of print hammer support members should
be adjusted by shifting them in equal distance. There is a possibility
that the adjustment of one end may be forgotten.
OBJECTS OF THE INVENTION
An object of the invention is to eliminate the disadvantages of
conventional mechanism by providing a mechanism for adjusting the
positions of print hammers, which is itself easy to be adjusted.
Another object of the invention is to provide a mechanism for adjusting
the positions of hammers which is simple in construction and low
A further object of the invention is to provide a mechanism for
adjusting the angle of the hammers so as to make the front end surfaces
of respective hammers parallel to those of the type characters when
both surfaces become unparallel.
Additional objects of the invention will be apparent from the following
descriptions which are to be read in conjunction with the accompanying
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of one embodiment of a printer mechanism
according to this invention;
FIG. 2 is schematic plan view of a printer mechanism showing one
embodiment of this invention;
FIG. 3 is a sectional view along the A--A line of FIG. 2;
FIG. 4 is a sectional view along the B--B line of FIG. 2;
FIGS. 5A and 5B are partially plan view showing the relation of
the positions between type characters and print hammers; and
FIG. 6 shows a side view of a mechanism for making a surface of
a type character and the front surface of a hammer parallel.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Referring to FIG. 1 the reference numeral 1 denotes a type belt
on which a number of embossed type characters are formed. The type
belt is wound about a driving pulley 3 and a driven pulley 4. The
type belt 1 shifts a row of type characters along a printing line
5 as shown in FIG. 3. The reference numeral 6 designates a multiplicity
of juxtaposed print hammers disposed on a print hammer support 7
through a leaf spring 8 as shown in FIG. 4.
The reference numeral 9 illustrates a plurality of electromagnetic
means confronting the associated print hammers 6 and secured to
an electromagnetic means support 10 respectively. The print hammer
support 7 is loosely fitted to hole in a guide member 12 secured
to a side plates 11 at the both right and left ends thereof so that
the support 7 can be shifted along the printing line 5.
The reference numeral 13 depicts a dial to which an adjusting rod
14 is secured by set screw. The rod 14 is provided at its end with
a screw portion 14a which is screwed to the electromagnetic means
support 10 and at the central portion with a hub 14b. The dial 13
is attached to a dial fitting plate 15 positioned between the hub
14b and the dial. The dial 13 is not capable of moving in the axial
direction of the adjusting rod 14 because the dial fitting plate
15 is screwed to the guide member 12.
The reference numeral 16 indicates a ball and 17 is a coil spring
which are enclosed in a blind hole in the dial 13 and forms a detent
mechanism with a number of blind holes 18 in the plate 16. Therefore
the position of the dial 13 can be determined for every rotation
of minute angle of the dial 13.
In operation, the print belt 1 is fed in accordance with the rotating
direction of the driving pulley 3 as shown by an arrow 3' in FIG.
2 and the type characters pass through each character station in
succession. During this operation, a type character position detecting
device (not shown) detects which printing digit position the characters
are aligned with. When the type character to be printed aligns with
the predetermined printing digit position, the electromagnetic means
operates causing the print hammer 6 which is driven through an armature
9a to impact to the type character 2 with a sandwiched record sheet
19 and ink ribbon 20 (shown in FIG. 4) thereby printing characters
on the record sheet 19 in succession. When the predetermined characters
are printed on one line of the record sheet 19 the record sheet
19 is advanced to another line and the same printing step is effected
for the next line.
When the record sheet is changed to a thicker sheet as when one
piece of sheet is changed to a plurality of sheets the following
FIG. 5A is an explanatory diagram showing the situation in which
one piece of record sheet is replaced by a plurality of sheets.
When the type character reaches to the place indicated by are actual
line, the print hammer is driven so as to separate from the place
indicated by an actual line and to move toward the record sheet.
The hammer 6 prints a character to be printed at the place shown
by dotted lines when the type character 2 reaches the place shown
by the dotted line because the thickness of the record sheet has
been increased by the change.
However, as clearly shows in FIG. 5A, there is deviation of the
positions between the type character 2 and the print hammer and
thereby correct printing can not be effected. Therefore, when a
record sheet is exchanged for another sheet or sheets different
thicknesses, the dial 13 is rotated as shown in FIG. 3. Rotation
of the dial shifts the electromagnetic support means in the printing
direction or rather parallel with the direction of the printing
The print hammer support 7 is shifted so that the print hammer
6 is shifted from the position indicated by the chain line to that
of the solid line, as shown in FIG. 5B. Therefore upon printing,
the positions of the type character 2 shown by a dotted line, and
print hammer 6 shown by a dotted line, are in accord with each
other so that correct printing may be effected.
The arrangement of shifting the print hammer by the rotation of
the adjusting dial 13 is not limited to situations in which printing
is performed after record sheets different in thickness are exchanged.
When printing is done on record sheets equal in thickness, a printer
mechanism of this invention is also useful when temperature changes
in the printer mechanism after long usage causes changes of electromagnetic
force of the electromagnetic device 9.
FIG. 6 shows an adjusting part to make the surfaces of a type character
2' and a front of a hammer 6' end parallel.
A guide member 12 is secured to a side plate by means of a screw
22. A pin 21 is inserted through a hole in the front end of the
guide member 12 and into the side plate 11. In order to parallel
the impacting surface of the print hammer 6' and the surface of
the type character 2', the screw 22 is loosened and the guide member
is pivoted about the axis of the pin 21 thereby inclining the impacting
surface of the hammer by the same rotational angle. As a result,
the surface of the type character 2' and the impacting surface of
the hammer are paralleled with one another.
As clearly understood from the above discussion, when record sheets
of different thickness are exchanged or when temperature in a printer
changes, the deviation of position between the print hammer and
type character is caused. In these situations the printer of this
invention can be adjusted only by shifting it in the printing direction,
i.e., adjusting one part so that parallelism of the print hammer
and the print belt can be maintained. This adjustment is very easy
and the struction for accomplishing the adjustment is simple.