JPH05254154A - Printing head - Google Patents

Abstract

PURPOSE:To provide a printing head which is capable of generating a compact powerful magnetic circuit and performing hammer drive action efficiently. CONSTITUTION:A magnetic assembly consisting of paired core members 22, 23, 27, 28, permanent magnets 24, 29 sandwiched between these core members and solenoid coils 25, 26, 30, 31 wound around each core member, arranged from the vertical center and the lower half of the yoke 21 of a printing head. In addition, the N and S magnetic poles of a top permanent magnet and a bottom permanent magnet are arranged so that these magnetic poles are mutually at an opposite position. The same polarities react against each other at the border between both magnetic assemblies, thus preventing a magnetic flux from leaking out. Consequently, a highly efficient magnetic circuit is formed, and an armature is perfectly attracted by the magnetic action of a permanent magnet as a powerful attractive force.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a print head, and more particularly to a print head capable of performing a hammering operation of a printing pin at high speed.

[0002]

2. Description of the Related Art With the recent development and popularization of OA equipment,
Printers are used as accessories for office computers and word processors in each office. There are various printing methods for such a printer, and examples of the structure of the print head of the printer that adopts the hammer striking method include those shown in FIGS. 4 and 5, for example.

This print head is attached by extending a front yoke 1 and a rear yoke 2 for forming an electromagnetic circuit, and extending from a side wall of the rear yoke 2 toward the front yoke 1 at an upper end portion of the rear yoke 2. A pair of pillar-shaped cores 3 and 4, and a permanent magnet 5 disposed between the cores 3 and 4 at a mounting end of the cores 3 and 4 to the rear yoke 2, Is wound around each of the cores 3 and 4 and electrically connected to the control circuit and the drive circuit,
Electromagnetic coils 6 and 7 for canceling the magnetic field of the permanent magnet 5 by electromagnetic action, a leaf spring 8 sandwiched between the connecting portions of the front yoke 1 and the rear yoke 2, and a tip end of the leaf spring 8 are attached. It consists of an armature 9 and a printing pin 10 fixedly attached to the armature 9 and forming a hammer for printing together with a leaf spring as a recording element. As is apparent from FIGS. 4 and 5, the armature 9 has a block structure and is integrally attached and fixed to the leaf spring 8 by adhesion or another method at a portion overlapping the leaf spring 8. .. The front yoke 1 has a pin through hole 11 at its tip, and the print pin 1 is passed through this pin through hole 11.
0 projects in front of the front yoke 1. Magnet member 3,
A plurality of sets (for example, 24 sets) of 4, 5, 6, 7 leaf springs 8 and print pins 10 are provided for one print head, and the tips of the print pins 10 for the number of sets face the platen surface. There is.

In such a structure, when the electric current is not conducted to the electromagnetic coils 6 and 7, the armature 9 is attracted by the magnetic action of the permanent magnet 5, and as shown in FIG.
The armature 9 is attracted to the cores 3 and 4 against the elastic force of the leaf spring 8. Therefore, the leaf spring 8 is flexibly deformed,
It stores elastic energy in itself.

On the other hand, during the operation of the print head, electric current is intermittently applied to the electromagnetic coils 6 and 7. When a current is applied to the electromagnetic coils 6 and 7, the electromagnetic coils 6 and 7 are excited to cancel the magnetic field generated by the permanent magnet 5. As a result, the leaf spring 8 becomes free and the repulsive force of the leaf spring 8 separates the armature 9 from the cores 3 and 4 (state of FIG. 4), and the printing pin 10 prints on the recording paper. When the electric current to the electromagnetic coils 6 and 7 is cut off, the armature 9 is turned on again by the permanent magnet 5.
Is adsorbed on the surfaces of the cores 3 and 4.

[0006]

By the way, in such a conventional hammer striking type print head,
When the state in which the current is conducted to the electromagnetic coils 6 and 7 (FIG. 4) is changed to the state in which the current is cut off (FIG. 5), the armature 9 is cored by the magnetic action of the permanent magnet 5. It has to be firmly attracted to and held by the magnets 3 and 4, but in order to efficiently perform this attraction and hold, the solid line M in FIG. 5 is provided between the cores 3 and 4, the permanent magnet 5 and the armature 9. A strong magnetic circuit as represented by must be formed. However, in an ordinary magnetic circuit, magnetic flux leakage occurs as indicated by a dotted line m in FIG. 5, and the magnetic flux leakage weakens the attractive force of the permanent magnet 5. Therefore, conventionally, it is necessary to use a permanent magnet 5 having a power larger than that which actually generates a necessary magnetic force, which leads to an increase in the size of a hammer portion and a large amount of current for canceling the magnetic field of the permanent magnet 5. Must be conducted to the electromagnetic coils 6 and 7.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a print head capable of generating a strong magnetic circuit, small in size, and capable of efficiently driving a hammer. Is.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a pair of core members in the upper half and the lower half from the vertical center of the yoke of the print head, and between the core members. A magnetic assembly composed of a permanent magnet mounted so as to be sandwiched between the core member and an electromagnetic coil wound around each of the core members is arranged, and the permanent magnet installed on the upper side and the magnetic assembly installed on the lower side. The gist is that the N and S magnetic poles of both the permanent magnet and the permanent magnet are arranged so as to have an opposite positional relationship.

[0009]

With the above construction, magnetic circuits are formed in the upper and lower magnetic assemblies, respectively. Since the magnetic poles of the N and S magnetic poles of the permanent magnets are arranged so as to be opposite to each other between both magnetic assemblies, leakage of magnetic flux does not occur in each magnetic assembly, and a high-rate magnetic circuit is formed. It is formed. Therefore, the magnetic action of the permanent magnet can be completely attracted to the armature and can be attracted with a strong attractive force.

[0010]

1 to 3 show an embodiment of a print head according to the present invention. Among these, FIG. 1 is a cross-sectional view showing a schematic configuration of the print head according to the embodiment, FIG. 2 is a front view showing the arrangement state of the magnetic assembly of the print head for a 9-pin array print head, and FIG. It is a front view showing the arrangement state of the magnetic assembly of a print head about the print head of a 24-pin arrangement. The print head according to this embodiment has a yoke member 21 having a substantially U-shaped vertical cross section that forms a common electromagnetic circuit on the upper side and the lower side, and protrudes forward in the upper half portion from the center of the yoke member 21 in the vertical direction. A pair of attached upper core members 22, 2
3 and the yoke member 2 of these upper core members 22 and 23
These upper core members 22, at the mounting end to 1,
An upper permanent magnet 24 attached in a sandwiched manner between 23, and an electromagnetic coil 25 wound around each of the upper core members 22 and 23 to change or cancel the magnetic flux of the upper permanent magnet 24, 26, and a pair of lower core members 27, 28 that are attached to the front half of the yoke member 21 so as to project forward in the lower half portion.
And the yoke member 21 of these lower core members 27, 28.
These lower core members 27, 2 at the end of attachment to
Lower permanent magnet 29 attached in a sandwiched manner between 8 and electromagnetic waves wound around the lower core members 27 and 28 in order to change or cancel the magnetic flux of the lower permanent magnet 29. The coils 30, 31 and the yoke member 2
1 are attached to both ends of the elastic member 1 so as to be elastically deformable, and extend in opposite vertical directions to the central portion of the yoke member 21.
Upper leaf spring 32 that performs a suction / repulsion motion with respect to 4 and 29
And the lower leaf spring 33, and the armatures 34, 35 attached to the tip portions of the leaf springs 32, 33, respectively.
And printing pins 36 and 37 as recording elements which are fixedly attached to the armatures 34 and 35 to form a hammer for printing and which prints on the recording paper in accordance with the attraction / repulsion movement of the leaf springs 32 and 33. It will be done.

Upper core members 22, 23, upper permanent magnet 2
4. The electromagnetic coils 25 and 26 form an upper magnetic assembly in the upper half of the yoke member 21, while the lower core members 27 and 28 and the lower permanent magnet 29 electromagnetic coils 30 and 3 are used.
Reference numeral 1 is a lower half portion of the yoke member 21 and constitutes a lower magnetic assembly. Further, the upper permanent magnet 24 and the lower permanent magnet 29 are arranged such that the N and S magnetic poles of both of them are in an opposite arrangement relationship. That is, in this embodiment, as shown in FIG. 1, the upper permanent magnet 24 is arranged so that the N pole is on the upper side and the S pole is on the lower side, while the lower permanent magnet 29 is the S pole on the upper side. It is arranged so that the N pole is below. Further, in this embodiment, the upper core member 2
The pair of 2 and 23 and the pair of lower core members 27 and 28 are arranged in a zigzag pattern with a half pitch in the horizontal direction when viewed from the front. Further, the print pin 36 attached to the upper leaf spring 32 and the print pin 37 attached to the lower leaf spring are arranged side by side in a straight line at a substantially central position in the vertical direction of the yoke member 21. Further, a plurality of sets of the magnetic assembly leaf springs 32, 33 armatures 34, 35 and the printing pins 36, 37 are provided for one print head as in the case of the conventional example described above. The tips of the printing pins 36 and 37 of the above are opposed to the platen surface. In the example of FIG. 2, the upper side 4
The print head is composed of a set of rows and the lower 5 rows, and in the example of FIG. 3, the print head is composed of a set of the upper 12 rows and the lower 12 rows.

The operation of the print head having the above structure will be described below. Electromagnetic coils 25, 26, 30, 31
When the electric current is not conducted to the armatures 34 and 35 by the magnetic action of the permanent magnets 24 and 29,
As shown in FIG. 1, these armatures 34 and 35 oppose the elastic forces of the upper and lower leaf springs 32 and 33, respectively, and the upper and lower core members 22, 23, 27 and 28, respectively.
Adsorb to. Therefore, the leaf springs 32 and 33 are flexibly deformed as shown in FIG. 1 to store elastic energy in themselves.

At this time, in the upper magnetic assembly, the upper core member 2 is operated by the action of the upper permanent magnet 24.
A magnetic circuit is formed between 2, 23 and the armature 34 in the direction opposite to that shown by the solid line M in FIG. Also,
In the lower magnetic assembly, the action of the lower permanent magnet 29 forms a magnetic circuit between the lower core members 27, 28 and the armature 35 in the same direction as shown by the solid line M in FIG. .. Then, the upper core member 23 and the lower core member 27 have the same poles facing each other and repel each other, which prevents leakage of magnetic flux from the other side. No magnetic flux leaks from the lower magnetic assembly as shown by the dotted line m in FIG. Therefore, the armature 34 has the upper core member 22,
23, and the armature 35 includes the lower core members 27, 2
8 is attracted by a strong suction force.

On the other hand, during the operation of the print head, a current is intermittently applied to the electromagnetic coils 25, 26, 30, 31. When a current is applied to the electromagnetic coils 25, 26, 30, 31, these electromagnetic coils 25, 26, 30, 31 are excited to cancel the magnetic flux generated by the permanent magnets 24, 29.
As a result, the leaf springs 32 and 33 become free, and the repulsive force of the leaf springs 32 and 33 causes the armatures 34 and 35 to move to the core members 22, 2 and 3.
Separated from 3, 27 and 28, the print pins 36 and 37 print on the recording paper. When the current to the electromagnetic coils 25, 26, 30, 31 is cut off, the armatures 34, 35 are again acted upon by the permanent magnets 24, 29 to cause the core members 22, 23,
It is adsorbed on the surfaces 27 and 28.

In the above embodiment, the upper leaf spring 3
The print pin 36 attached to the No. 2 and the print pin 37 attached to the lower leaf spring 33 are arranged in a straight line at a position substantially at the center of the yoke member 21 in the vertical direction. It is not limited. That is, the print pin 36 attached to the upper leaf spring 32 and the print pin 37 attached to the lower leaf spring 33 are disposed at a substantially central position in the vertical direction of the yoke member 21 with a certain pitch interval in the vertical direction. They may be arranged side by side in two rows. With such a structure, there is a merit that a space for disposing the print pins 36 and 37 can be provided and a print head can be easily manufactured.

[0016]

As described above, according to the present invention,
A pair of core members, a permanent magnet attached in a form sandwiched between these core members, and a core member of the core member in the upper half and the lower half of the yoke in the vertical direction of the hammer striking type print head, respectively. Place a magnetic assembly consisting of an electromagnetic coil wound around each,
Since the N and S magnetic poles of both the permanent magnets incorporated in the upper side and the permanent magnets incorporated in the lower side are arranged so as to have mutually opposite arrangement relations, at the boundary portion between both magnetic assemblies. The same magnetic poles repel each other to prevent leakage of magnetic flux. For this reason, a high-ratio magnetic circuit is formed, and the magnetic action of the permanent magnet is completely attracted to the armature and is attracted by a strong attractive force. Therefore, high-speed printing can be performed without increasing the magnetic force of the permanent magnet.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration of a print head according to an embodiment of the present invention.

FIG. 2 is a front view showing the arrangement state of the magnetic assembly of the print head of the above-described embodiment for a print head having a 9-pin arrangement.

FIG. 3 is a front view showing the arrangement state of the magnetic assembly of the print head of the embodiment described above with respect to the print head having a 24-pin arrangement;

FIG. 4 is a cross-sectional view showing a configuration example of a conventional print head.

FIG. 5 is a partially enlarged sectional view showing a magnetic circuit formed in the conventional example.

[Explanation of symbols]

 21 yoke member 22, 23 upper core member 24 upper permanent magnet 25, 26, 30, 31 electromagnetic coil 27, 28 lower core member 29 upper permanent magnet 32, 33 leaf spring 34, 35 armature 36, 37 printing pin

Claims (4)

[Claims] 1. A yoke member having a substantially U-shaped vertical cross-section forming a magnetic circuit, and an upper core mounted in a pair in the upper half of a vertical center of the yoke member so as to extend vertically and to project forward. A member, an upper permanent magnet mounted between the upper core members at the mounting end of the upper core member to the yoke member, and a coil wound around each of the upper core members to vary the magnetic flux of the upper permanent magnet. The mounted electromagnetic coil and the yoke member are vertically paired at the lower half of the center of the yoke member so as to project in the forward direction, and are attached to the upper core member in the horizontal direction by a half pitch. A lower core member, a lower permanent magnet mounted between the lower core members at their mounting ends to the yoke member, and a lower permanent magnet. Electromagnetic coils wound around each of the lower core members in order to change the magnetic flux of, and elastically deformably attached to both ends of the yoke member, and extending in opposite vertical directions to the central portion of the yoke member, Non-conduction of coil current / adsorption to / from permanent magnet by conduction action
An upper leaf spring and a lower leaf spring that perform a repulsive movement, an armature that is attached to the leaf spring to form a hammer for printing, and that is attached to the armature and prints on the recording paper in accordance with the attraction / repulsion movement of the leaf spring. A print head, comprising: a print pin, wherein the upper permanent magnet and the lower permanent magnet are arranged such that the N and S magnetic poles of the upper permanent magnet and the lower permanent magnet have an opposite positional relationship. 2. The print head, wherein the pair of upper core members and the pair of lower core members are arranged in a zigzag pattern with a predetermined pitch offset from each other. 3. The printing pin attached to the upper leaf spring and the printing pin attached to the lower leaf spring are arranged side by side in a straight line at a substantially central position in the vertical direction of the yoke member. head. 4. The printing pin attached to the upper leaf spring and the printing pin attached to the lower leaf spring are arranged in two rows with a certain pitch interval in the up and down direction substantially at the center of the yoke member in the up and down direction. A print head characterized by being arranged.