JPH051407Y2 - - Google Patents

Description

[Detailed explanation of the invention] [Industrial application field] This invention is used in serial printers to store the magnetic energy of a permanent magnet as strain energy in a leaf spring, and convert this into printing energy by energizing a coil corresponding to printing data. The present invention relates to a wire dot print head that converts and prints.

[Conventional technology]

Conventionally, various wire dot printing heads of this type have been implemented, for example,
There are those shown in FIGS. 6 and 7.

Figure 6 is a configuration diagram showing a conventional spring charge type wire dot printing head, and Figure 7 is B-B in Figure 6.
FIG.

In FIG. 6 and FIG. 7, 1 is a permanent magnet;
2 is the rear yoke, 3〓, 3〓, 3〓 is the core, 4〓, 4
〓, 4〓 are coils, 5 is a leaf spring, 6〓, 6〓, 6〓 are armatures, 7 is a printing wire, 8 is a front yoke, and 9 is an intermediate yoke.

A permanent magnet 1 is attached to the outer edge of the rear yoke 2.
An intermediate yoke 9 and a front yoke 8 are stacked, and the fixed end of the leaf spring 5 is held between the front yoke 8 and the intermediate yoke 9. An armature 6 is supported at the free end of the leaf spring 5, and a printing wire 7 is attached to the tip of the armature 6.
The base of the printing wire 7 is fixed, and the tip of the printing wire 7 is arranged so as to protrude from the guide portion at the center of the head.

Further, a core 3 is provided at the center of the rear yoke 2, and a coil 4 is wound around the outer periphery of the core 3 to form an electromagnet.

In this configuration, when the coil 4 is not energized,
The magnetic flux of the permanent magnet 1 flows from the intermediate yoke 9 to the front yoke 8.
→ Armature 6 → Core 3 → Rear yoke 82
At this time, a magnetic attraction force is generated between the core 3 and the armature 6, so that the armature 6 is attracted to the core 3, causing the leaf spring 5 to deform into a loose S-shape, and strain energy is accumulated.

When the coil 4〓 is energized in this state, the magnetic flux of the coil 4〓 cancels the magnetic flux of the permanent magnet 1 in the space between the core 3〓 and the armature 6〓, so that the armature 6〓 moves away from the core 3〓. To be released.
As a result, the strain energy stored in the leaf spring 5 is released, and as the leaf spring 5 recovers, the armature 6 rotates clockwise in the drawing using the corner of the core 3 as a fulcrum. 6
The tip of the printing wire 7 fixed to the holder jumps out in front of the guide portion and hits the printing medium via an ink ribbon (not shown) to perform printing.

During this printing, the magnetic path of the magnetic flux caused by the coil 4 follows the same magnetic path 10 of the magnetic flux caused by the permanent magnet 1 in the opposite direction, but the permanent magnet 1 has almost the same permeability as air, and the magnetic flux Since it has a large resistance to passage, part of the magnetic flux of the coil 4 passes through the magnetic paths 12a and 12b passing through the adjacent cores 3 and 3 in addition to the magnetic path, as shown in FIG. Causes leakage.

Adjacent armatures, for example 6〓 and 6〓
When both are driven at the same time, the magnetic flux from the coil 4 is flowing into the core 3, and its direction is opposite to the magnetic flux produced by the coil 4.

Therefore, the magnetic flux caused by the coil 4 is reduced, resulting in a decrease in inductance and an increase in demagnetizing current in the coil 4.

This results in an increase in power consumption and heat generation, resulting in a delay in the drive operation of the armature.

This phenomenon is called magnetic interference, but this magnetic interference is relative, and the coil 4 is also affected by the magnetic flux of the coil 4.

Further, magnetic interference can occur to some extent even between cores that are not adjacent to each other, although the degree of interference is alleviated depending on the distance between them.

Therefore, as a means for reducing this magnetic interference, methods as shown in FIGS. 8 and 9 have been proposed.

FIGS. 8 and 9 are configuration diagrams showing the first means and the second means.

This first means provides a bypass magnetic path 13 to reduce the magnetic resistance seen from the coil side, secure a magnetic path for the demagnetized magnetic flux, and reduce the shunting of the demagnetized magnetic flux to other cores to reduce magnetic interference. This is what I did.

Specifically, a bypass magnetic path 13 is provided in which the core 3 and the intermediate yoke 9 are connected by a magnetic member, and the bypass magnetic path 13 is provided with a magnetic resistor for adjusting the magnetic resistance as shown in FIG. A small hole 14 as shown in Japanese Patent Publication No. 2003-110000 is formed, or a gap G as shown in FIG. 9 is formed.

However, in the first means and second means having the above configuration, since the bypass magnetic path is provided near the permanent magnet, a large amount of the magnetic flux of the permanent magnet is shunted, and the opposing portion of the core and armature is sufficient. In order to obtain a strong attractive force, a strong permanent magnet is required, but when such a strong permanent magnet is used, there is a tendency for magnetic saturation to occur in the bypass magnetic path, making it difficult for the magnetic flux to pass through the bypass magnetic path. The problem was that the road no longer functioned properly.

Therefore, the first method to solve this problem is
The one shown in Figure 0 was proposed.

FIG. 10 is a block diagram showing the third means disclosed in Japanese Patent Laid-Open No. 58-33476 and Japanese Patent Laid-Open No. 58-65672.

This third means includes magnetic material 15 between adjacent cores.
A magnetic path for the degaussing magnetic flux is secured by providing a magnetic member or injecting a filling magnetic material.

[Problem that the invention attempts to solve]

However, even in the third means of the above structure, since a magnetic material is provided near the permanent magnet, the above problem is still not solved in terms of the inflow of magnetic flux of the permanent magnet, and furthermore, the problem between the adjacent cores is still unsolved. Since the magnetic material is provided on the printhead, there is a problem in that the printing head becomes large.

This idea was made to solve the above problem, and it is a wire dot that efficiently flows demagnetizing magnetic flux without leaking the magnetic flux caused by the permanent magnet, eliminates magnetic interference, and improves power and space saving. The purpose is to provide a print head.

[Means for solving problems]

In order to achieve this object, the present invention is such that a leaf spring is held between a front yoke on the side of a permanent magnet provided on the outer periphery of the head, and the armature is driven by the magnetic flux of the permanent magnet passing through the front yoke, the armature, and the core. The armature is driven by the restoring force of the leaf spring when the core is attracted and the leaf spring is deflected, and the magnetic flux of the permanent magnet is canceled by the demagnetizing magnetic flux of the coil wound around the core, and the armature is released from the core. In a wire dot printing head that performs printing using a printing wire fixed to the tip of the armature, a center pole having a height lower than the core is provided at a position opposite to the permanent magnet and close to the core; The tip extends through the air to face the center pole to form a bypass magnetic path in which a portion of the demagnetizing magnetic flux of the coil flows from the core to the center pole through the armature, and The yoke is characterized by extending to face the armature across the air.

[Effect]

In the present invention having such a configuration, the distance between the permanent magnet and the center pole is long, and when the magnetic flux of the permanent magnet tries to pass through the center pole, the magnetic flux is distributed between the air between the front yoke and the armature and the armature. Since the magnet must pass through the air between the magnet and the center pole, the magnetic resistance to the magnetic flux of the permanent magnet that tries to flow to the center pole when the armature is attracted to the core increases.

Therefore, the magnetic flux of the permanent magnet passing through the center pole is extremely small, the magnetic efficiency of the permanent magnet is improved, and sufficient attractive force to the armature can be obtained without the need for a strong permanent magnet.

In addition, part of the degaussing magnetic flux generated by energizing the coil when releasing the armature, that is, the leakage magnetic flux, tends to flow from the armature through one hole to the bypass magnetic path that passes through the center pole near the core. , there is almost no flow to adjacent cores, so magnetic interference is prevented.

〔Example〕

Hereinafter, embodiments of this invention will be described in detail based on the drawings.

Note that the same members as those in the conventional example are given the same reference numerals and the explanation thereof will be omitted.

FIG. 1 is a sectional view showing one half of a wire dot printing head according to an embodiment of this invention, and FIG. 2 is a sectional view taken along the line A--A in FIG.

In both figures, 16 is a center pole made of magnetic material, and this center pole 16 is connected to the core 3.
It is provided close to the core 3 at a position opposite to the permanent magnet 1, has a height lower than the core 3, and has a cylindrical shape so as to be shared by each core 3. One is provided as a.

Further, in this embodiment, the tip of the armature 6 is extended to face the center pole 16 through the air, so that a part of the demagnetizing magnetic flux of the coil 4 flows from the core to the center pole through the armature. A bypass magnetic path 17 is formed, and a front yoke 8 is extended to face the armature 6 with an air gap in between.

Since the printing operation of the wire dot print head having the above structure is the same as that of the conventional example, the explanation thereof will be omitted, and only the effect of the bypass magnetic path of the demagnetizing magnetic flux will be explained.

When the armature 6 is in the home position, the armature 6 is attracted to the core 3 by the attractive force of the permanent magnet 1 and is in a biased state.

In this biased state of the armature 6, the magnetic path of the magnetic flux caused by the permanent magnet 1 is mainly indicated by the arrow 10, but regarding the leakage magnetic path passing through the center pole 16, the distance between the permanent magnet 1 and the center pole 16 is long. , Moreover, when the magnetic flux of the permanent magnet 1 attempts to pass through the center pole, the magnetic flux must pass through the air between the front yoke 8 and the armature 6, and the air between the armature 6 and the center pole 16. Therefore, when the armature 6 is attracted to the core 3, the magnetic resistance to the magnetic flux of the permanent magnet 1 that tries to flow to the center pole increases,
Therefore, the magnetic flux flowing through the center pole 16 is extremely small.

Also, a current is applied to the coil 4, and the armature 6
When releasing the coil 4, part of the demagnetizing magnetic flux by the coil 4 avoids the magnetic path that passes through the permanent magnet 1 in the direction opposite to the arrow 10, which is difficult to flow, and flows through the bypass magnetic path 17, which is easy to flow. The rate at which the parts flow into other cores 3 is significantly reduced compared to the conventional example.

The experimental results will be explained with reference to FIGS. 3 and 4. FIG. 3 is a graph showing the relationship between the attractive force acting between the armature and the core with respect to the magnetizing field of the permanent magnet, and FIG. 4 is a graph showing the relationship between the number of wires and power consumption during simultaneous operation.

A comparative experiment was conducted between this embodiment and the conventional example (second means) shown in FIG. 9 under the following settings.

Except for the center pole 16 and the bypass magnetic path 17 for demagnetizing magnetic flux, the setting conditions for both print heads, such as the material, length, and cross-sectional area of the magnetic path, are the same.
Center pole 16, demagnetizing magnetic flux bypass magnetic path 1
7 is also set to have the same material and cross-sectional area.

First, the force required to separate the armature 6 adsorbed from the core 3 was measured, and the experimental data shown in the graph of FIG. 3 was obtained.

As is clear from this experimental data, in the case of this example, the attractive force is increased by 30% with the same magnetizing field compared to the conventional example.

The degaussing current was then measured by operating multiple wires simultaneously.

For the measurements, a dot printing head with 24 wires was used, and the simultaneous operation of 12 wires, which is the maximum number of wires that can be operated simultaneously, was measured, and the experimental data shown in the graph of Figure 4 was obtained. I got it.

As is clear from this experimental data, the degaussing current ratio to the current value when one wire is operated tends to increase as the number of wires operated simultaneously increases.

The tendency for the degaussing current ratio to increase is reduced by about 20% compared to the conventional example.

FIGS. 5A and 5B are block diagrams showing a second embodiment of this invention.

This second embodiment has almost the same structure as the previous embodiment, but differs only in the shape of the center pole.

That is, the center pole 16 shown in FIG.
The center pole 16b shown in FIG. 5B has a columnar shape and takes charge of the bypass magnetic path of all the demagnetizing magnetic flux. It is provided for each core 3 so as to take charge separately.

The operation and experimental results of this second embodiment are almost the same as those of the first embodiment, so their explanation will be omitted.

[Effect of idea]

As explained above, the present invention provides a center pole with a height lower than the core at a position opposite to the permanent magnet and close to the core, and also has the tip of the armature facing the center pole through the air. The coil is extended so as to form a bypass magnetic path in which a portion of the degaussing magnetic flux of the coil flows from the core to the center pole through the armature, and the front yoke is opposed to the armature through the air. Since the structure is extended to the following, the following effects can be obtained.

First, if the distance between the permanent magnet and the center pole is long and the magnetic flux of the permanent magnet tries to pass through the center pole, the magnetic flux will flow through the air between the front yoke and the armature and the air between the armature and the center pole. 〓, the magnetic resistance to the magnetic flux of the permanent magnet that tries to flow to the center pole increases when the armature is attracted to the core, and as a result, the magnetic flux of the permanent magnet that passes through the center pole becomes extremely small. It can be expected that the magnetic efficiency of the magnet will be improved and that sufficient attractive force for the armature can be obtained without the need for a strong permanent magnet.

In addition, part of the degaussing magnetic flux generated by energizing the coil when releasing the armature, that is, the leakage magnetic flux, tends to flow from the armature through one hole to the bypass magnetic path that passes through the center pole near the core. Since almost no flow flows to adjacent cores, it is possible to prevent magnetic interference.

Furthermore, since the center pole is provided in the center of the head, which was conventionally a dead space, it is possible to avoid increasing the size of the printing head, which has been a problem in the past.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram showing a wire dot printing head according to the first embodiment of this invention, Fig. 2 is a sectional view taken along the line A-A in Fig. 1, Fig. 3 is a graph showing suction force characteristics, and Fig. 4 5 is a block diagram showing the second embodiment, FIG. 6 is a block diagram showing the conventional example, FIG. 7 is a sectional view taken along line B-B in FIG. Figures 9 and 10 show the first and second improved versions of the conventional example.
FIG. 2 is a configuration diagram showing two and three means. 1...Permanent magnet, 2...Rear yoke, 3,3〓
~3〓...Core, 4,4〓~4〓...Coil, 5...
...Plate spring, 6,6〓~6〓...Armature, 7...
...Printing wire, 8...Front yoke, 9...Middle yoke, 10...Magnetic flux path by permanent magnet, 1
6, 16a, 16b...center pole, 17...
...Bypass magnetic path for demagnetizing magnetic flux.

Claims (1)

[Claims for Utility Model Registration] A leaf spring is held between a front yoke on the side of a permanent magnet provided on the outer periphery of the head, and the armature is attracted to the core by the magnetic flux of the permanent magnet passing through the front yoke, armature, and core. the leaf spring is bent, and the armature is driven by the restoring force of the leaf spring when the armature is released from the core by canceling the magnetic flux of the permanent magnet with the demagnetizing magnetic flux of the coil wound around the core. In a wire dot printing head that prints using a printing wire fixed to the tip of the armature, a center pole with a height lower than the core is provided at a position opposite to the permanent magnet and close to the core, and the tip of the armature is empty. Extend it to face the center pole through the
A bypass magnetic path is formed in which a part of the demagnetizing magnetic flux of the coil flows from the core to the center pole through the armature, and the front yoke is extended to face the armature across the air. Features a wire dot printing head.