JPH04105945A - Printing head for wire dot type printer - Google Patents

Abstract

PURPOSE:To prevent wear of the contact part of a side magnetic passage by a method wherein a high rigidity sheetform spacer is located between a shaft mounted on the fulcrum part of an armature and the side magnetic passage. CONSTITUTION:When selective energization is applied on a coil 11, a corresponding armature 2 is attracted to an attraction surface 9b of a yoke 9 by means of the magnetomotive force of the coil 11, and the attracted armature 2 is rotated anticlockwise around the fulcrum part of the armature. a printing paper is struck with the tip of a print wire 1 mounted on the tip of the armature 2 to perform given printing. When printing is completed, since the coil 11 is released from energization thereto, the armature 2 is returned to an initial position togetherwith the print wire 1 through the force of a return spring 5. In which case, when the armature 2 effects rotation around a shaft 14 serving as a fulcrum, since a high rigidity sheetform spacer 20 is located between the shaft 14 and the contact part of a side magnetic passage 7, the contact part of the side magnetic passage 7 is prevented from wear.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a print head for use in a wire dot printer.

[Conventional technology]

FIG. 4 is a half-sectional view showing an example of a conventional print head.

As shown in FIG. 4, a conventional print head used in a wire dot type printer has a shaft 34, which serves as a fulcrum for the rotational movement of an armature 22, which is brought into direct contact with a side magnetic path 24 by means of a jab l to a presser foot 24. It is composed of

[Problem to be solved by the invention]

As mentioned above, in the printing part of the conventional wire dot type printer, the shaft is in direct contact with the side magnetic path, so during the printing operation, the side magnetic path slides with the jar 71, and the time is reduced. The side magnetic path wears out over time. For this reason, the armature may operate unstable, or the amount of wear on the contact parts of the magnetic paths on each side for each armature may vary, resulting in variations in the stroke of each armature, resulting in variations in the density of the printed results. It has the disadvantage that it occurs.

[Means to solve the problem]

A print head for a wired dot type printer according to the present invention includes a plurality of armadures and a print wire that performs printing by striking a printing surface by the rotational movement of the armature.
A shaft with a circular cross section provided at the fulcrum of the armature, a shaft holder that holds one side of the shaft, the opposite side of the shaft (7 side magnetic paths provided, and the shirt); A highly hard thin plate-shaped spacer is provided between the side magnetic path and the side magnetic path.

〔Example〕

Next, two embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a half-sectional view showing one embodiment of the present invention, FIG. 2 is an enlarged sectional view of the main part of the embodiment of FIG. 1, and FIG. 3 is a side sectional view of the embodiment of FIG. 1. .

In FIG. 1, a head frame 12 accommodates a plurality of print wires that reciprocate and one or more guides 15 to guide their movement. A drive unit for reciprocating the printed wire 1 includes a yoke 9, a side magnetic path 7, an outer yoke 8, an inner yoke 210, an armature 2, and a coil 1. The armature 2 is provided so as to face the suction surface 9b of the yoke 9.

As shown in FIGS. 2 and 3, the armature 2 is
The spacer 20 is pressed by the force of the pressure comb 3 via the shaft 1 to the presser foot 4.

The armature 2 can rotate around the shaft 14 between the stopper rubber 13a and the suction surface 9b. Further, a return spring 5 is provided in the armature support 6, one end of which is in contact with the armature 2, and the armature 2 is pressed by this return spring 5 against the stomba comb 13a provided at the tip of the stopper 3. has been done.

On the other hand, the print wire 1 has its rear end fixed to the end of the armature 2, and its tip end connected to the guide F]5 and J housed in the head frame 12.
It is held in a predetermined position by a guide hole 19a provided in the guide 19 via guide holes 15a, 16a, 17a, and 18a of 6, 17, and 18.

In such a configuration, when the coil 1 corresponding to each armature 2 is selectively energized, the magnetomotive force of the coil 1 causes the corresponding armature 2 to move toward the attraction surface 9 of the yoke 9.
b, and the attracted armature 2 rotates counterclockwise about its fulcrum. by this,
The tip of the print wire 1 attached to the tip of the armature 2 hits the printing paper to perform predetermined printing. When printing is completed, the current to the coil 11 is removed,
The armature 2 returns to its original position together with the print wire by the force of the return spring 5.

As shown in FIGS. 2 and 3, when the armature 2 rotates around the shaft 14, there is a high-hardness material between the shaft 14 and the contact portion (abutment portion) of the side magnetic path 7. For example, a thin plate-shaped spacer can be hardened to a Rockwell C hardness of 45 to 65 ■-■R by hardening SKS material.
By interposing the hardened material 20, it is possible to prevent the contact portion of the side magnetic path 7 from being worn out.

As a method for hardening the spacer, in addition to the above-mentioned examples, similar effects can be obtained by nitriding or carburizing.

〔Effect of the invention〕

As explained above, the print head of the wire dot type printer of the present invention has a high hardness thin plate-like spacer between the shaft provided at the fulcrum of the armature and the side magnetic path. This has the effect of preventing wear on the contact parts, and therefore there is no variation in the stroke of each armature even during long printing operations, resulting in a print head with a long life and excellent reliability. There is an effect.

[Brief explanation of the drawing]

1 is a half-sectional view showing an embodiment of the present invention, FIG. 2 is an enlarged sectional view of the main part of the embodiment of FIG. 1, and FIG. 3 is a side sectional view of the embodiment of FIG. FIG. 4 is a half-sectional view showing an example of a conventional print head. 1. Print wire, 2.22.. Armature, 3.. Pressure rubber, 4.24..
Shaft holder, 5...Return spring, 6...
..., armature support, 727... side magnetic path,
8...Outer yoke, 9...Yoke, 9 b
...Suction surface, 1-0-...Inner yoke, 1
1...Coil, 12...To Sodoframe,
13...stopper, 13a...-stopper rubber, ]4.34...shaft, 1516.17.1
819...Guide, 15a 16a 17a・1
．． 8 a 1.9 a... Guide hole, 20 spacer.

Claims (1)

[Scope of Claims] 1. In a print head of a wire dot type printer that includes a plurality of armatures and a print wire that performs printing by hitting a print surface by rotational movement of the armature, a fulcrum portion of the armature A shaft with a circular cross section provided, a shaft holder that holds one side of the shaft, and a side magnetic path provided on the opposite side of the shaft;
A print head for a wire dot type printer, comprising: a highly hard thin plate-shaped spacer provided between the shaft and the side magnetic path. 2. The print head for a wire dot type printer according to claim 1, wherein the material for the spacer is an SK5 material hardened to a Rockwell C hardness of 45 to 65H_RC.