JPH0719796Y2 - Wire dot print head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a wire dot print head in a serial printer.

(Prior Art) Conventionally, a serial printer using a wire dot print head has a high degree of freedom of a print medium and is advantageous in that copy paper or the like can be used, and thus high demand can be obtained. Further, the wire dot print head drives the wire by the magnetic attraction force of a permanent magnet or an electromagnet.

The impact printer is classified into a plunger type, a spring charge type, and a clapper type according to the type of the wire dot print head.

Among them, in the spring charge type, an armature to which a printing wire is fixed is swingably supported by a biasing leaf spring, and the armature is previously supported by a permanent magnet against the elastic force of the biasing leaf spring. When the core is attracted and printing is performed, the coil wound around the core is excited to generate a magnetic flux in the direction opposite to that of the permanent magnet to release the armature. Therefore, this spring charge type wire dot printing head, which has a good high-speed response, is often used.

On the other hand, the clapper type, on the other hand, energizes and energizes the coil at the time of printing to attract the armature to the coil,
It has a structure for printing.

By the way, in the spring charge type wire dot print head, the leakage magnetic flux from the electromagnet for canceling the magnetic flux of the permanent magnet may cause magnetic interference and flow into the adjacent armature and core to change the magnetic flux. . The change in the magnetic flux due to the magnetic interference increases as the number of dot wires printed at the same timing increases, and when the armatures are released, a larger excitation current is required than when each armature is actuated independently. Increasing the amount of heat generated by the head.

Further, since the change of the exciting current also affects the operation of the armature after the release, it is necessary to control the energization time of the coil according to the number of dot wires to be printed at the same timing.

In particular, when speeding up the spring-charged wire dot print head to increase the print output, reduce power consumption, and further reduce the size and perform high-density mounting,
Due to the magnetic interference, power consumption further increases and heat is generated.

Therefore, there has been provided a magnetic flux which passes through adjacent cores in mutually opposite directions and utilizes magnetic interference (see JP-A-58-96568).

According to this, the permanent magnets are arranged in the respective cores such that the polarities of the adjacent permanent magnets are opposite to each other, and the independent side yokes, leaf springs and upper yokes are laminated on the permanent magnets. It

The wire dot print head is shown in FIGS.

FIG. 6 is a sectional view of a conventional wire dot print head, FIG.
FIG. 8 is a sectional view taken along the line AA in FIG. 6, and FIG. 8 is a perspective view of a main part of a conventional wire dot print head.

In the figure, reference numeral 11 denotes a circular lower frame, which is integrally formed of a non-magnetic material such as aluminum. 12 is a plurality of substantially L-shaped independent cores,
11 and the tip corresponding to the center of the print head rises to form a plurality of convex portions. And
A coil 13 is wound around the convex portion to form an electromagnet 14, and a permanent magnet 15 is laminated on the rear end of the core 12, that is, the circumferential portion of the print head. The permanent magnets 15 are arranged so that the polarities of the permanent magnets 15 laminated on the adjacent cores 12 are opposite to each other.

16 is a side yoke laminated on the permanent magnet 15, 17 is a leaf spring having a free end at a position facing the electromagnet 14, 18 is an armature fixed to the free end, and 19 is an upper portion arranged on the upper surface of the leaf spring. The yokes 20 are upper frames provided on the upper yoke 19, which are integrally formed of a non-magnetic material such as aluminum, and the print wires 22 project in a predetermined arrangement from a wire guide 21 provided at the center. In addition, 23 is the permanent magnet
15 Side yoke 16, leaf spring 17, and upper yoke stacked on top of each other
A fixing screw for fixing the 19 and the upper frame 20 together, and the fixing screw 23 is fastened in the same number as the leaf spring 17.

Next, the operation of the dot print head thus configured will be described.

When not printing, the electromagnet 14 is not excited and the permanent magnet 15
However, as shown by arrow e, side yoke 16, upper yoke 19,
Form a loop of magnetic flux through the armature 18 and core 12. As a result, the core 12 attracts the armature 18 against the force of the leaf spring 17 and biases the leaf spring 17 so that the printing wire
Attract 22.

Further, when selectively printing one arbitrary print wire 22 for printing, the coil 13 corresponding to the print wire 22 is energized. At this time, as shown by arrows f and g, a loop of the magnetic flux passing through the armature 17, the upper yoke 19 and the side yoke 16 is formed in the direction opposite to the magnetic flux of the permanent magnet 15 to cancel the magnetic flux in the direction of the arrow e. The armature 18 that had been sucked into the core 12 is released. As a result, the leaf spring 17 is restored, the dot wire 22 is driven, and desired dot characters are printed on the printing paper.

The magnetic flux indicated by the arrow g at this time forms a loop in the direction opposite to the magnetic flux indicated by the arrow h of the adjacent permanent magnet 15 to form a loop.
In order to cancel the magnetic flux of the adjacent coils 13, the magnetic flux of each coil 13 flows into the adjacent cores 12 to form a magnetic flux in the opposite direction to the magnetic flux of the permanent magnets 15 of the cores 12. The magnet 14 can be excited even if the power consumption is low.

However, in the above wire dot print head,
Since the permanent magnets 15 corresponding to the respective dot wires 22 are independent of each other and the polarities of the adjacent permanent magnets 15 are opposite to each other, when manufacturing the wire dot print head, the permanent magnets in a non-magnetized state are used. After forming the structure of the print head using 15, the permanent magnet 15 cannot be magnetized to a desired strength in a strong magnetic field. That is, it is necessary to assemble the permanent magnet 15 magnetized in advance to an arbitrary strength to the print head, resulting in a complicated and difficult manufacturing process.
Therefore, not only the permanent magnets 15 but also the leaf springs 17 and the like need to be manufactured as independent parts, which increases the cost of the product.

Therefore, the integral type permanent magnet is so arranged that the directions of the magnetic fluxes of the permanent magnets passing through the armature-core are opposite to the directions of the magnetic fluxes of the adjacent armature-core without reversing the polarities of the adjacent permanent magnets. Are provided.

Further, FIG. 9 is a plan view of a main part of another conventional wire dot printing head, FIG. 10 is a sectional view taken along the line BB in FIG. 9, FIG. 11 is a sectional view taken along the line CC, and FIG. FIG. 13 is a perspective view of a main part of a dot print head, and FIG. 13 is an exploded perspective view of the same.

Cores with two types of cross sections as shown in FIGS. 10 and 11.
35 are alternately arranged in a radial pattern as shown in FIG. 9 to form a print head.

In the figure, 31 is an armature having a print wire 33 fixed to its tip, 32 is a leaf spring having the armature 31 fixed to its free end by laser welding, 34 is a permanent magnet, and 35 is a core. Also
36 is a back pole that forms the pivot of the armature 31, 37 is a base plate that alternately fixes the core 35 and the back pole 36 in the circumferential direction, 38 is a ring that forms the fixed end of the leaf spring 32, and 39 is a permanent magnet. A magnet plate for alternately fixing the core 35 and the back pole 36 on the 34, 40 is a screw for fixing the magnet plate 39, the permanent magnet 34 and the base plate 37, 41 is an exciting coil wound around the core, and 42 is Inserted between the core 35, the back pole 36, and the leaf spring 32, and a rescue sheet arranged to protect the surface of the core 35 and the pivot of the armature 31, and 43 is a ring 38.
Together with forming the fixed end of the leaf spring 32, and wire guide 44
Is a head frame for positioning. The head frame 43 and the base plate 37 are attached to the leaf spring 32 by a screw 45.
It is attached to the ring 38 across.

Next, the operation of the wire dot print head having the above configuration will be described.

In the non-printing state, the coil 41 is not energized, and in the portion where the permanent magnet 34 is arranged as shown in FIG. 10, the permanent magnet 34 causes the magnetic flux loop passing through the core 35, the armature 31, the back pole 36 and the base plate 37. 46 is formed.
As a result, the armature 31 is attracted to the core 35 against the force of the leaf spring 32, and the leaf spring 34 is biased to store strain energy.

On the other hand, in the portion shown in FIG. 11, a magnetic flux loop 47 passing through the back pole 36, the armature 31, the core 35 and the base plate 37 is similarly formed by the permanent magnet 34.
31 is attracted to the core 35.

Further, here, the polarities of the adjacent magnetic flux loops 16 and 17 work in opposite directions.

Next, in FIG. 12, when selectively driving an arbitrary dot wire 33 for printing, the exciting coil 41-b corresponding to the dot wire 33 is energized and the magnetic flux of the permanent magnet 34 is changed as indicated by arrow e. It forms a magnetic flux in the opposite direction to the loop 47. At this time, a part of the magnetic flux generated by the coil 41-b flows into the adjacent armature 31-a and core 35-a.
The direction of this magnetic flux depends on the adjacent armature 31-a and core.
The direction is opposite to the magnetic flux 46 generated by the permanent magnet 34 flowing through 35-a, that is, the direction in which the magnetic flux of the permanent magnet 34 is canceled.

Therefore, when the coil 41-b and the adjacent coil 41-a are simultaneously energized, a part of the exciting magnetic flux of the coil 41-b flows into the core 35-a, so that the coil 41-a is independently excited. A predetermined printing operation can be performed with a smaller exciting magnetic flux f. That is, the power consumption can be reduced.

In the wire dot print head having the above structure, as shown in FIG. 13, an integral permanent magnet 34 is used, and it is possible to adopt a manufacturing process in which magnetization is performed after the print head is assembled. Is reduced.

(Problems to be solved by the invention) However, since the core 35 having two types of structures is adopted in the wire dot print head having the above configuration,
A difference occurs in the magnetic force that attracts the armature 31 between the two. That is, the magnetic path having the structure shown in FIG. 11 attracts the armature 31 less than the magnetic path having the structure shown in FIG. 10, resulting in variations in the operating characteristics of the armature 31.

The force of attracting the armature 31 is the amount of magnetic flux flowing from the core 35 to the armature 31 (or flowing from the armature 31 to the core 35) and the back pole 36 to the armature 31.
It depends on the amount of magnetic flux that flows into (or flows into the back pole 36 from the armature 31), but most depends on the former. The amount of magnetic flux is determined by the force of the permanent magnet 34, the magnetic path material and magnetic resistance, and the leakage magnetic flux. Therefore, see Fig. 10 and
Comparing the magnetic paths in Fig. 11, in the former case, since the permanent magnet 34 is directly below the core 35, the distance between the attraction surface of the core 35, that is, the facing surface of the armature 31 and the facing surface is short, and the magnetic resistance is large between them. Since there are no parts, the leakage of magnetic flux into the space is small.

On the other hand, in the latter magnetic path, since the permanent magnet 34 is far from the attraction surface of the core 35, the leakage of magnetic flux between them is large.
Since the distance between the suction surface of 34 and the back pole 36, that is, the surface facing the armature 31, is short, the magnetic flux density in that portion is high, and the magnetic path is easily saturated.

Therefore, the amount of magnetic flux on the core surface is larger in the magnetic path of FIG. 10 than in the magnetic path of FIG. 11, and in the case of the magnetic path of FIG. 11, the attraction force of the armature 31 is small.

Therefore, an armature having different shapes suitable for each magnetic path is provided alternately.

FIG. 14 is a view showing an armature in a wire dot print head according to still another conventional embodiment, and FIG.
The top view of the armature arranged in the magnetic path shown in the figure, 14th
Figure (B) is the same side view, Figure 14 (C) is a plan view of the armature arranged in the magnetic path of Figure 11, Figure 14 (D) is the same side view, and Figure 15 is the same as Figure 14. It is a layout of an armature.

The armature 31b shown in FIGS. 14 (C) and (D) is
Compared with the armature 31a of FIGS. (A) and (B), an area increasing portion 31c is formed in a portion facing the back pole 36. By combining this armature 31b with the core 35 shown in FIG. 11, it is possible to prevent a saturation phenomenon in a portion near the permanent magnet 34 and having a high magnetic flux density. as a result,
The magnetic resistance is reduced, and the amount of magnetic flux flowing between the core and the armature can be increased.

Therefore, a combination of the core 35 of FIG. 10 and the armature 31a of FIGS. 14A and 14B, the core 35 and the core of FIG.
When a combination of the armatures 31b shown in FIGS. (C) and (D) is alternately arranged as shown in FIG. 15, the difference in suction force generated between the two can be reduced.

However, since the armatures 31a and 31b are movable parts, changing the shape of the armatures 31a and 31b causes a change in weight, which changes the printing characteristics of the print head during actual printing. Therefore, the area where the area-increasing portion 31c of the armature 31b is formed is limited to the vicinity of a portion that serves as a fulcrum during armature operation.
It is difficult to make the amount of magnetic flux flowing into the core portion in the figure completely the same.

Further, there is provided a magnetic pole having two systems in which the shape of a plurality of back poles arranged in the circumferential direction is alternately changed depending on the arrangement position of the permanent magnets.

FIG. 16 is a perspective view of a back pole in still another conventional wire dot printing head in which two systems of magnetic paths are formed, FIG. 16 (A) is a perspective view of the first back pole, and FIG. 16 (B) is a perspective view. The back pole perspective view of FIG. 17 is a plan view of the yoke, FIG.
The figure is a perspective view of the main part of the wire dot print head with the head frame removed.

As shown in the figure, the back pole 56a has a quadrangular prism shape, and the back pole 56b has a "U" shape at the portion a of the yoke 51.
It has a V shape and is arranged at the portion b of the yoke 51.

By incorporating the back poles 56a, 56b and the yoke 51, in the case of the back pole shown in FIG. 11, there was only a magnetic path of the permanent magnet 34 → the back pole 36 → the armature 31 → the core 35, whereas the permanent magnet is newly added. 34 → back pole 56
Since a magnetic path of b → yoke 51 → armature 31 → core 35 is added, the amount of magnetic flux flowing in the core 35 can be increased.

However, even in this case, it is difficult to completely adjust the amount of magnetic flux in the magnetic path shown in FIG. 10 and the magnetic path shown in FIG. 11, and the work cost for processing the back pole is high.

The present invention solves the above-mentioned problems of the conventional wire dot print head, and the wire manufacturing method is easy, magnetic interference is small, energy efficiency is high, and there is no difference in printing characteristics due to a difference in magnetic path structure. It is an object to provide a dot print head.

(Means for Solving the Problem) Therefore, in the wire dot printing head of the present invention, a plurality of back poles that are aligned in the circumferential direction and form the pivotal fulcrum of the armature, and are arranged inside them. A plurality of cores are provided, and a pair is formed by both. In each pair of the back pole and the core, a pair in which a permanent magnet is arranged on the back pole side and a pair in which a permanent magnet is arranged on the core side are arranged alternately.

Further, the pair of back poles in which the permanent magnets are arranged on the back pole side have the areas of the surface facing the armature and the surface facing the permanent magnets as compared with the pair of back poles in which the permanent magnets are arranged on the core side. It's big.

The magnetomotive force of the pair of permanent magnets having the permanent magnets on the back pole side may be larger than that of the pair of permanent magnets having the permanent magnets on the core side.

(Operation) According to the present invention, a wire in which permanent magnets are alternately arranged below the core or back pole without changing the polarities of the permanent magnets so that the directions of the adjacent magnetic fluxes are opposite to each other as described above. In the dot print head, the pair of back poles having permanent magnets on the back pole side has a surface facing the armature and a surface facing the permanent magnets as compared to the pair of back poles having permanent magnets on the core side. The area of is enlarged.

Therefore, it is possible to prevent magnetic saturation in a portion near the permanent magnet where the magnetic flux density is high, and reduce the magnetic resistance.

Also, by increasing the surface area or volume of the permanent magnet and increasing its magnetomotive force, it is possible to increase the amount of magnetic flux flowing through the core.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a perspective view of a main part of a wire dot print head of the present invention, FIG. 2 is a perspective view of a back pole used in the wire dot print head of the present invention, and FIG. 2 (A) is a first back pole. FIG. 2 (B) is a perspective view of the second back pole.

As shown in the figure, a plurality of back poles 61a and 61b having two kinds of shapes are arranged outside the plurality of cores 35 so as to form a pair with each core 35.

In each pair of the core 35 and the back poles 61a and 61b, the permanent magnet 34 is laminated only on the core 35 side, and the permanent magnet 34 is laminated on both the core 35 side and the back pole 61b side. The pairs and are arranged alternately.

That is, for the core having the structure shown in FIG.
The back pole 61a of FIG. 11 corresponds to the second back pole 61b for the core having the structure shown in FIG.

As shown in FIG. 2, the first back pole 61a has a quadrangular prism shape, and the second back pole 61b is chamfered above the quadrangular prism to form a tapered portion 62.

The second back pole 61b has a larger area of a portion facing the armature 31 and the permanent magnet 34 than the first back pole 61a. Second back pole 61b in FIG.
The broken line indicated by indicates the portion corresponding to the outer surface of the first back pole 61a.

As a result, it is possible to prevent saturation of the magnetic path near the permanent magnet 34 where the magnetic flux density is high, reduce the magnetic resistance, and increase the amount of magnetic flux flowing through the core 35.

FIG. 3 is a view showing a permanent magnet of a wire dot print head according to another embodiment of the present invention, and FIG. 4 is a view showing an additional magnet,
5 is a sectional view of the permanent magnet of FIG. 3 when an additional magnet is attached, FIG. 5 (A) is a sectional view taken along line AA, and FIG. 5 (B).
FIG. 6 is a sectional view taken along line BB.

As shown in FIG. 3, the permanent magnet 34 has an a portion with a short diameter,
It has a shape with alternating long b-parts.
The permanent magnet 34 is arranged so that the portion a is located with respect to the core having the structure shown in the figure and the portion b is located with respect to the core having the structure shown in FIG.

Then, as shown by the shaded area C,
The area of the permanent magnet 34 is increased only in the portion corresponding to the core having the structure shown in FIG.

In addition, the fan-shaped additional magnet 34a as shown in FIG.
It is also possible to superimpose it on part b as shown in FIGS. In this case, the volume of the permanent magnet 34 increases only for the core having the structure shown in FIG.

As described above, by increasing the surface area or volume of the permanent magnet 34, it is possible to increase the magnetomotive force in the magnetic path shown in FIG. 11 and increase the amount of magnetic flux flowing in the core 35.

When a part of the magnetic circuit is saturated, no matter how much the magnetomotive force is increased, the leakage magnetic flux only increases and the effect is not so great. Therefore, this embodiment can be implemented in combination with the above-described embodiments. It is valid.

The present invention is not limited to the above embodiment,
Various modifications are possible based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

(Effect of the Invention) As described in detail above, according to the present invention, the core of the pair of the core and the back pole is arranged so that the directions of the adjacent magnetic fluxes are opposite to each other without changing the polarities of the permanent magnets. Alternatively, since the permanent magnets are alternately arranged under the back pole, magnetic interference does not occur and energy efficiency is improved.

In addition, the pair of back poles with permanent magnets on the back pole side has a smaller area of the surface facing the armature and the surface facing the permanent magnets than the pair of back poles with permanent magnets on the core side. Since it is made large, it is possible to prevent magnetic saturation in the portion near the permanent magnet where the magnetic flux density is high, and reduce the magnetic resistance.

Further, by increasing the surface area or volume of the permanent magnet and increasing the magnetomotive force thereof, the amount of magnetic flux flowing in the core can be increased.

Therefore, in each pair in which permanent magnets are alternately arranged under the core or the back pole, the amount of magnetic flux flowing into the core can be made the same without increasing the manufacturing cost,
There is no difference in printing characteristics due to the difference in magnetic path structure.

[Brief description of drawings]

FIG. 1 is a perspective view of a main part of a wire dot print head of the present invention, FIG. 2 is a perspective view of a back pole used in the wire dot print head of the present invention, and FIG. 2 (A) is a first back pole. FIG. 2 (B) is a perspective view of the second back pole, FIG. 3 is a view showing a permanent magnet of a wire dot print head showing another embodiment of the present invention, and FIG. 4 is an additional magnet. FIG. 5 is a sectional view of the permanent magnet of FIG. 3 when an additional magnet is attached, FIG. 5 (A) is an AA sectional view, and FIG. 5 (B) is a BB sectional view. FIG. 6 is a sectional view of a conventional wire dot print head, FIG. 7 is a sectional view taken along the line AA of FIG. 6, FIG. 8 is a perspective view of a main part of a conventional wire dot print head, and FIG. FIG. 10 is a plan view of a main part of a conventional wire dot print head, FIG. 10 is a sectional view taken along the line BB of FIG. 9, and FIG.
-C sectional view, FIG. 12 is a perspective view of a main part of the wire dot print head, FIG. 13 is an exploded perspective view of the wire dot print head,
FIG. 14 is a view showing an armature in a wire dot print head according to still another conventional embodiment, and FIG.
The top view of the armature arranged in the magnetic path shown in the figure, 14th
Figure (B) is the same side view, Figure 14 (C) is a plan view of the armature arranged in the magnetic path of Figure 11, Figure 14 (D) is the same side view, and Figure 15 is the same as Figure 14. The armature layout, FIG. 16 is a back pole perspective view of still another conventional wire dot printing head in which two systems of magnetic paths are formed, and FIG. 16 (A) is a first back pole perspective view. (B) is a perspective view of the second back pole, FIG. 17 is a plan view of the yoke, and FIG. 18 is a perspective view of an essential part of the wire dot print head with the head frame removed. 31 ... Armature, 34 ... Permanent magnet, 35 ... Core, 61a, 61b
... back pole.

Claims (3)

[Scope of utility model registration request] 1. An armature having a print wire fixed to its tip, a core provided to face the armature, a leaf spring to which the armature is joined and supported in a cantilever manner, and a magnetic flux is generated. A permanent magnet for attracting the armature to the core against the elastic force of the leaf spring, and a coil wound around the core to generate a magnetic flux from the core by energization and cancel the magnetic flux of the permanent magnet to release the armature. In a wire dot print head consisting of (a) a plurality of back poles aligned in the circumferential direction and forming a pivotal fulcrum of the armature, and (b) inside each of them so as to form a pair with each back pole. A plurality of cores to be provided, (c) each pair of back pole and core, a pair having a permanent magnet on the back pole side, and a permanent magnet on the core side And (d) the pair of back poles with permanent magnets on the back pole side are more armature-like than the pair of back poles with permanent magnets on the core side. A wire dot printing head, characterized in that the areas of the facing surface and the surface facing the permanent magnet are increased. 2. An armature having a printing wire fixed to the tip thereof, a core provided to face the armature, a leaf spring to which the armature is joined and supported in a cantilever manner, and a magnetic flux generated by the armature. A permanent magnet that attracts the armature to the core against the elastic force of the leaf spring, and a coil that is wound around the core and that generates a magnetic flux from the core by energization and cancels the magnetic flux of the permanent magnet to release the armature. In the wire dot printing head consisting of (a) a plurality of back poles aligned in the circumferential direction and forming a pivotal fulcrum of the armature, and (b) arranged inside each of them so as to form a pair with each back pole. A plurality of cores provided, (c) each pair of back pole and core, a pair in which a permanent magnet is arranged on the back pole side, and a permanent magnet on the core side And (d) the permanent magnets of the pair having permanent magnets on the back pole side have a larger magnetomotive force than the permanent magnets of the pair having permanent magnets on the core side. A wire dot print head characterized in that 3. A pair of back poles having permanent magnets arranged on the back pole side has a surface facing the armature and a surface facing the permanent magnets, as compared with a pair of back poles having permanent magnets arranged on the core side. The wire dot print head according to claim 2, wherein the area of the wire dot is large.