JPH0469250A - Print head - Google Patents

Abstract

PURPOSE:To prevent deviation of a position of a supporting point of an armature so as to make it possible to realize an exceedingly stable operation in a print head for a dot matrix printer by making the supporting point by engaging a V-shaped groove arranged on the armature with a round bar having a circular section. CONSTITUTION:A side magnetic path 7 is provided with a side magnetic path groove on an opposing face of an inner yoke 10, an annular supporting point ring 14 is embedded therein, engaged with a V-shaped armature groove 2a arranged on an opposing face of an armature 2 so as to constitute a supporting point. The armature 2 is freely rotatable centering around the supporting point ring 14 between a stopper rubber 13a and an attracting face 9b. At that time, since the armature V-shaped groove 2a is pressed to the supporting point ring which is fixed by the side magnetic path groove and the inner yoke 10, a movement of the supporting point is prevented. Also, since a position of the supporting point ring 14 is positioned by the side magnetic path groove, a position of the supporting point does not vary at every armature 1, so that a uniform characteristic can be obtained and a print head having a stable print quality and a long life can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a print head, and particularly to a print head used in an impact type dot matrix printer.

[Conventional technology]

Conventionally, this type of print head performs printing by transmitting the rotational movement of an armature, which forms part of the magnetic circuit, to a printing wire attached to the armature and hitting the printing surface. For this purpose, a projection or edge provided on the armature is brought into contact with a flat surface of the fixing member, or conversely, an edge portion of the securing member is brought into contact with a flat surface of the armature.

FIG. 4 is a vertical half-sectional view of a typical conventional print head in which a protrusion provided on the armature, which serves as a fulcrum for rotational movement of the armature, butts against a flat surface of an inner yoke, which is a fixed member. In FIG. 4, a plurality of printing wires 1 that reciprocate and guides 15, 16 to 18 and 19 for guiding the printing wires 1 are housed in the head frame 12. The drive unit that reciprocates the plurality of printing wires 1 has a yaw of 9. Side magnetic path 27. Outer yoke 8. Inner yoke 10.
Armature 22. It is composed of a magnetic core 9a connected to a yoke 9 and a coil 11, and an armature 22 is provided facing an attraction surface 9b of the magnetic core 9a. The armature 22 also holds its protrusion on the inner yoke 1 via the hold spring 3 by the force of the pressure rubber 4.
0 and is rotatable between the stopper rubber 13a and the suction surface 9b using this protrusion as a fulcrum, but is normally pressed against the stopper rubber 13a by the return spring 5 whose one end is in contact with the armature 22. On the other hand, the rear end of the printing wire l is fixed to the rotating end of the armature 22, and the tip of the printing wire l is connected to the guides 15, 16.
- 19 are guided by guide holes 15a, 16a - 19a and held in a predetermined position.

In the above structure, by selectively energizing the coil 11, the armature 22 is caused by the magnetomotive force of the coil 11.
is attracted to the suction surface 9b, rotates counterclockwise in the drawing about the fulcrum, and predetermined printing is performed by the tip of the printing wire 1 fixed to the tip of the armature 22. After printing, the current to the coil 11 is cut off, and the armature 22 returns to its initial position together with the printing wire 1 due to the extension of the return spring 5.

[Problem to be solved by the invention]

In the above-mentioned conventional print head, one of the fulcrums of the armature is a flat surface, and while the positioning is adapted to another mechanical member, the position may shift during printing operation, resulting in unstable operation. However, since the fulcrums of each of the plurality of armatures are positioned separately, there is a drawback that minute variations in the fulcrum positions for each armature may manifest as variations in print density.

[Means to solve the problem]

The print head of the present invention has a plurality of armatures, and is a print head of an impact-type dot matrix printer that uses a rotary motion of the armature to drive a print wire to strike a print surface to print. forming a center of rotational movement of the armature by engaging the rod with a V-shaped groove provided in the armature;
Further, the round rod having a circular cross section is an annular body having a circular cross section, and is configured by engaging with a V-shaped groove provided in all the armatures.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a longitudinal half-sectional view of one embodiment of the present invention. In this embodiment, a round member with a circular cross section constituting a fulcrum is provided in an annular shape and engaged with a V-shaped groove provided in all armatures. Indicates when

FIG. 2 is an enlarged view of a portion centered on the armature in FIG. 1, and FIG. 3 is a sectional view taken along the line AA in FIG. 2. 1st
In the figure, head frame 12. -Guide 15-19.
Printing wire 1. York 9. Outer yoke 8. Innayo 210. Magnetic core 9a, coil 11. Pressure rubber 4. Hold spring 3, return spring, stopper 1
3. The stopper rubber 13a is the same as that of the conventional print head shown in FIG.
4 is fitted, and the fulcrum ring 14 of armature 2
A V-shaped armature groove 2a is provided on the opposing surface of the armature, and engages with the fulcrum ring 14 to form a fulcrum.

With the above configuration, the armature 2 is rotatable about the fulcrum ring 14 between the stopper rubber 13a and the suction surface 9b as in the conventional case. Furthermore, when the armature 2 rotates around the fulcrum, the fulcrum is prevented from moving because it is fixed by the side magnetic path groove 7a and the inner yoke 10 and the armature V arm 2a is pressed against the fulcrum ring. Since the fulcrum ring 14 is positioned by the digit 1 of the side magnetic path fi7a, the fulcrum position does not differ for each armature 1.

In addition, in the above embodiments, the round member with a circular cross section constituting the fulcrum was annular and common to all armatures, but this round member can be used as a round bar provided for multiple armatures or a single armature. do not have.

〔Effect of the invention〕

As explained above, in the present invention, a round material is passed between the inner yoke and the groove provided in the side magnetic path, and this round material is engaged with the V-shaped groove provided in the fulcrum part of the armature to serve as the fulcrum. Without shifting the position of the armature fulcrum,
The armature operates extremely stably, and there is no variation in the fulcrum position for each armature, resulting in uniform characteristics, which has the effect of providing a good print head with stable print quality. Furthermore, since the fulcrum part does not shift, there is less wear on the fulcrum part, which has the effect of providing a highly reliable print head with a long life.

A sectional view and FIG. 4 are vertical half sectional views of a typical conventional print head.

l... Printing wire, 2.22... Armature, 2
a... Armature ■, 3... Hold spring, 4... Pressure rubber, 5... Return spring, 6... Armature support, 7, 27...
Side magnetic path, 7a... Side magnetic path groove, 8... Outer yoke,
9... Yoke, 9a... Magnetic core, 9b... Attraction surface,
10... Inner yoke, 11... Coil, 12...
・Head frame, 13...stopper, 13a...
Stopper rubber, 14... Fulcrum ring, 15. ~19・
...Guide, 15a, ~19a... Guide hole.

Claims (1)

[Claims] 1. In the print head of an impact-type dot matrix printer that has a plurality of armatures and prints by driving a printing wire and hitting the printing surface by the rotational movement of the armature, the print head has a circular cross section. A print head characterized in that the center of rotation of the armature is formed by engaging a round bar with a V-shaped groove provided in the armature. 2. The round bar with a circular cross section according to claim 1 is an annular body of a round member with a circular cross section, and all the armatures are provided with V.
A print head characterized in that it engages a glyph groove.