JPH0437788B2 - - Google Patents

Description

[Detailed description of the invention] Technical field of invention This invention relates to dot printer heads.

TECHNICAL BACKGROUND OF THE INVENTION AND PROBLEMS THEREOF Conventionally, there has been a dot printer head in which an armature faces a core and a yoke to which a coil is attached, and the armature is operated together with a needle by the excitation action of the coil to perform printing. In order to obtain sufficient magnetic flux, it is necessary to increase the opposing area between the armature and the core as well as the opposing area between the armature and the yoke, but if this opposing area is expanded on the same plane, from the fulcrum of the armature to the center of the core The distance becomes longer and the equivalent mass of the armature becomes larger, making it impossible to perform high-speed printing. For this reason, means for forming a side magnetic path from the side surface of the armature to the yoke via a magnetic material has been adopted. A conventional example is shown below.

First, the invention described in Japanese Unexamined Patent Application Publication No. 141717/1983 as shown in FIG. 3 will be described. This consists of a coil 2 attached to a core 3 screwed onto a yoke 1, and an individual armature 5 to which a plunger 4 facing the core 3 is fixed.
and a petal-shaped leaf spring 6 are connected by a pin 7,
A ring-shaped magnetic body 8 into which each plunger 4 is fitted is screwed to the yoke 1 so as to face the end faces of the yoke 1 and the core 3, and a film 10 is interposed between the magnetic body 8 and the armature 5. It is equipped.
Therefore, the core 3, the armature 5, the magnetic body 8,
A magnetic path leading to the yoke 1 and the core 3 is formed, and a side magnetic path is formed around the plunger 4 of the armature 5, to the inner peripheral surface of the hole 9 of the magnetic body 8, to the magnetic body 8 and the yoke 1. However, since it is difficult to accurately position the armature 5 held by the leaf spring 6, in order to slidably fit the plunger 4 of the armature 5 into the hole 9 of the magnetic body 8, it is necessary to Therefore, the magnetic permeability between the plunger 4 and the hole 9 deteriorates, and the purpose of forming a side magnetic path is lost.

Next, FIG. 4 shows the invention described in Japanese Unexamined Patent Publication No. 141720/1983. Note that the same parts as those explained in FIG. 3 will be explained using the same reference numerals. In this conventional example, a bobbin 11 that holds a coil 2 and is fitted into a core 3 has a protrusion 13 that fits into a notch 12 formed on the outer periphery of a magnetic body 8, and a protrusion 13 formed on the outer side of an armature 5. A protrusion 15 is formed to fit into the hole 14, and the plunger 4 of the armature 5 is fitted into the hole 9 of the magnetic body 8. Therefore, a side magnetic path is formed from the outer circumference of the plunger 4 to the magnetic body 8 via the outer circumference of the hole 9 of the magnetic body 8.
However, when the magnetic body 8 is positioned by the protrusion 13,
Although the protrusion 15 can position the outside of the armature 5, it is not possible to prevent the inner end of the armature 5 from twisting. Even if a separate armature guide is provided to prevent the inner end of the armature 5 from swinging out, the relative position between the armature 5 and the magnetic body 8 will change due to accumulation of manufacturing errors, and the hole 9 of the magnetic body 8 will change.
Unless the clearance between the plunger 4 and the plunger 4 is increased, the operation of the plunger 4 will become unsmooth, resulting in a problem similar to that shown in FIG.

Purpose of the Invention The present invention was made in view of the above points, and it is possible to increase the magnetic flux density in the side magnetic path and reduce the opposing area between the yoke and the armature on the attraction surface of the core. The object of the present invention is to provide a dot printer head that can achieve high-speed printing and save power by reducing the equivalent mass of the dot printer.

Summary of the Invention The present invention provides an armature having a suction surface facing the core and an elongated extension extending from a widened edge of one end of the suction surface, facing the core and a yoke, and fitting the armature. An armature guide made of a magnetic material and having a guide groove that allows the core, armature, yoke,
In addition to forming a magnetic path leading to the core, a side magnetic path is formed that extends to the outer edge of the armature, the opening edge of the guide groove, the armature guide, and the yoke.By forming the side magnetic path with the armature guide, the armature and the guide groove are connected. It is possible to reduce the clearance of the side magnetic path, and to increase the magnetic flux density of the side magnetic path.Moreover, the armature is biased in the radial direction by the deformation of the needle, and its expanded edge is aligned with the opening edge of the guide groove. By constantly contacting the armature, the armature is prevented from rubbing against the opening edge of the guide groove when the armature moves up and down, thereby preventing wear on both, and further increasing the magnetic permeability of both.
Therefore, the opposing area between the armature and the yoke on the suction surface of the core is reduced, the equivalent mass of the armature is reduced, and high-speed printing and power saving are achieved.

Embodiment of the Invention An embodiment of the invention will be described with reference to FIGS. 1 and 2. Coil 1 is installed around the outer periphery of the annular yoke 16.
A plurality of cores 18 holding the yoke 7 are formed in succession, and fins 19 are formed on the back surface of the yoke 16. The armature 20 facing the yoke 16 and the core 18 extends inward from a wide suction surface 22 facing the suction surface 21 of the core 18 and a widening edge 23 at the inner end of the suction surface 22. Extension portion 24
The rear end of the needle 25 is connected to the inner end of the extending portion 24. Further, the extending portion 24 is thinner than the suction surface 22 so that there is a gap on the yoke 16 side, and therefore, the portion where the expansion edge 23 and the suction surface 22 intersect is supported by the yoke 16. An edge-shaped fulcrum 26 is formed.

Next, the armature guide 27 and the guide frame 28 are sequentially stacked on the yoke 16 and fixed with screws 29. The armature guide 27 is made of a magnetic material and is formed into an annular shape, and includes the peripheral edge of the attracted surface 22 of the armature 20 and the extending portion 24.
A guide groove 30 is formed radially into which a part of the peripheral edge of the guide groove 30 is fitted with a small clearance.
The guide holder 28 holds needle guides 31 and 32 that align the needles 25 while curving them, a spring 33 that returns the armature 20, and a ring-shaped armature stopper 34 made of a rubber material. The needle 25 exhibits an action of returning to a straight line due to its own elasticity, and as a result, the armature 20 is urged inward in the radial direction of the armature guide 27. Further, when the coil 17 is not energized, the armature 20 faces the core 18 with a gap, and the expanded edge 23 is substantially inclined with respect to a straight line perpendicular to the end surface of the yoke 16. Guide groove 30 with which the expanding edge 23 contacts
A portion of the groove 35 is substantially inclined with respect to a straight line perpendicular to the plane of the armature guide 27. That is,
When the coil 17 is not energized, the entire enlarged edge 23 of the armature 20 is in surface contact with a portion of the edge 35 of the guide groove 30.

In such a configuration, when the coil 17 is energized, the armature 20 is attracted to the core 18 and rotates about the fulcrum 26, and the needle 25 collides with the platen to perform printing. At this time, core 18, amateur 20, yoke 16, core 18
A magnetic path is formed that leads to amateur 2.
0, the opening edge of the guide groove 30, the armature guide 27, and a side magnetic path reaching the yoke 16. In this way, since the side magnetic path is formed by the armature guide 27 made of a magnetic material, the clearance between the armature 20 and the guide groove 30 can be reduced, and the elasticity of the needle 25 allows the armature 20 to expand. Since the edge 23 contacts the edge 35 of a part of the opening edge of the guide groove 30,
The magnetic permeability between the armature 20 and the armature guide 27 is high, and the magnetic flux density can be increased.
Thereby, the attraction force of the core 18 can be increased, and the capacity of the coil 17 can be reduced to save power. In addition, the suction surface 22 of the amateur 20
The area facing the yoke 16 can be reduced, and the fulcrum 26 can be moved closer to the core 18 to
The equivalent mass of 0 can be made small, and high-speed printing can therefore be made possible.

Furthermore, the armature 20 is the fulcrum 2 of the expansion edge 23.
Since the edge portion on the 6 side is always in elastic force contact with the opening edge of the guide groove 30 of the armature guide 27, the fulcrum 26 moves on the yoke 16 and the expansion edge 2
3 will not rub against the guide groove 30,
Therefore, wear can be prevented.

Effects of the Invention Since the present invention is constructed as described above, the armature guide is formed of a magnetic material to form the side magnetic path, thereby reducing the clearance between the guide groove of the armature guide and the armature, thereby forming the side magnetic path. The magnetic flux density can be increased, which increases the attraction force of the core and reduces the power consumption to drive the coil.The fulcrum is moved closer to the core, reducing the equivalent mass of the armature and enabling high-speed printing. Furthermore, by biasing the armature in the radial direction of the armature guide by deformation of the needle and bringing the expanded edge into contact with the opening edge of the guide groove of the armature guide, the fulcrum is fixed during the raising and lowering movement of the armature. This prevents the armature from moving or the widening edge of the armature from rubbing against the guide groove of the armature guide, and therefore has the effect of preventing wear of the armature and the armature guide.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional side view showing one embodiment of the present invention, FIG. 2 is a plan view of the armature and armature guide, and FIGS. 3 and 4 are partial longitudinal sectional side views showing a conventional example. 16... Yoke, 17... Coil, 18... Core, 20... Amateur, 22... Attracted surface, 2
3... Expansion edge, 24... Extending portion, 25... Needle, 26... Fulcrum, 27... Armature guide,
30...Guide groove.

Claims (1)

[Claims] 1. A yoke is provided along the arrangement direction of a plurality of cores arranged in an annular shape holding coils, and a yoke is provided along the arrangement direction of a plurality of cores arranged in an annular shape, and a yoke is provided that extends thinly from a wide attracting surface facing the core and a widened edge at the inner end of this attracting surface. A plurality of armatures each having an extending portion extending out from the yoke and having an elastic needle fixed to the tip of the extending portion are provided so as to be able to rise and fall freely with the contact portion with the yoke as a fulcrum, and an annular armature in contact with the yoke. The air guide is formed of a magnetic material, a plurality of guide grooves are formed in the armature guide in which the armature is fitted with a small clearance, and a side magnet is formed between the opening edge of these guide grooves and the peripheral edge of the armature. form a road,
The needle is bent and disposed so that the armature is biased in the radial direction of the armature guide so that the enlarged edge of the armature is always in contact with a part of the opening edge of the guide groove. dot printer head.