Wire dot printer head and wire dot printer

Details Wire dot printer head and wire dot printer Wire dot printer head and wire dot printer

2003-09-03

2004-10-19

Evanisko, Leslie J. (Department: 2854)

Typewriting machines

Typing by other than type-face or type-die

Character formation by impact

C400S124120, C101S093050

Reexamination Certificate

active

06805503

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a wire dot printer head and a wire dot printer.
2. Discussion of the Background
A wire dot printer head is an apparatus which performs printing by rocking, between a waiting position and a printing position, an armature with a printing wire connected thereto, to strike the front end of the wire on a printing medium such as a sheet when the armature is rocked to the printing position.
As the wire dot printer head, there has been developed an apparatus for printing by the use of a magnetic circuit which attracts an armature from a waiting position to a printing position with a magnetic flux formed by a coil around the armature to be rocked. As shown in
FIGS. 14 and 15
, in such a wire dot printer head
100
, an armature
102
supporting a printing wire
101
has a support shaft
103
. The armature
102
is supported rotatably on the center of the support shaft
103
. An armature spacer
105
has a cutout section
104
in which the support shaft
103
of the armature
102
is fitted, and is mounted on a yoke
106
for the formation of the magnetic circuit. On the armature spacer
105
, a plate
108
is provided to hold the support shaft
103
which restricts the movement of the armature
102
through an elastic spacer
107
elastically fixing the position of the support shaft
103
of the armature
102
. It is possible to thereby prevent abrasion of the plate
108
likely to be caused by the support shaft
103
of the armature
102
, and accordingly to fix the position of the support shaft
103
.
With recent speedups of printing operation, however, the armature
102
is likely to violently vibrate during printing because of such a high-speed movement between the printing position and the waiting position as 2500 times per second. The support shaft
103
, on the center of which the armature
102
rotates, therefore, tends to abrade the surface of the yoke
106
. It is generally because the yoke
106
is formed of a softer magnetic material than the support shaft
103
of the armature
102
. If the surface abrasion of the yoke
106
proceeds, the support shaft
103
of the armature
102
will move off position, resulting in unstable rocking operation of the armature
102
and accordingly in a deteriorated printing quality.
Furthermore, the support shaft
103
of the armature
102
is moved not only in the rocking direction of the armature
102
but in the radial direction of the armature spacer
105
by vibrations caused by the speedups of the printing operation, resulting in unstable rocking operation of the armature
102
. Furthermore, if the surface abrasion of the yoke
106
caused by the support shaft
103
of the armature
102
proceeds, the armature
102
for instance will contact the coil flange and the support shaft
103
will make fine vibrations to rub off stock of the cutout section
104
of the armature spacer
105
. Consequently, a shortened life of the wire dot printer head
100
will result.
SUMMARY OF THE INVENTION
It is, therefore, an object of this invention to provide wire dot printer head and wire dot printer which are capable of restraining the abrasion of the yoke surface in order to prevent the deterioration of printing quality.
The object of this invention can be accomplished by novel wire dot printer head and wire dot printer of this invention.
Therefore, according to the novel wire dot printer head and wire dot printer of this invention, there are provided, on a yoke for holding a plurality of armature support shafts, an abrasion preventive member which encloses the outer periphery of the armature support shafts, together with an armature spacer having a plurality of cutout sections in which the armature support shafts for supporting a printing wire are inserted. Thus it is possible to prevent the direct contact of the armature support shafts with the yoke.


REFERENCES:
patent: 4767227 (1988-08-01), Mitsuishi et al.
patent: 6698956 (2004-03-01), Terao et al.
patent: 3-007351 (1991-01-01), None
patent: 6-218954 (1994-08-01), None
patent: 2001-219586 (2001-08-01), None

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