JPH05254155A - Printing head of dot impact-type printer - Google Patents

Abstract

PURPOSE:To save at electric current which runs through a coil and to obtain a sufficient printing force. CONSTITUTION:A yoke 1 in which a permanent magnet 2 is incorporated has a core part 1a around which a coil 3 is wound and an auxiliary yoke 1b protruding in one piece. In addition, a leaf spring 6 is fixed to a ring yoke 4 fastened to a permanent magnet 2, through a spacer 5. Further, an armature 7 in an opposite position to the ends of the core 1a and the auxiliary yoke 1b, is fixed to the leaf spring 6. The armature 7 is attracted by the core part 1a and the auxiliary yoke 1b by elastically deforming the leaf spring 6 due to the magnetism of the permanent magnet 2. A printing wire 9 is firmly attached to the armature 7 through an arm 8. If the coil 3 is energized, the magnetic flux of the core part 1a due to the permanent magnet is cancelled and thereby the printing wire 9 is driven. Thus the electric current running through the coil 3 by the auxiliary yoke 1b is minimum and a reaction force which the printing wire 9 receives and a reversed force work on the armature 7 to ensure a strong printing force.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention releases an armature magnetically attracted to a core portion by applying a current to a coil wound around the core portion of the yoke to cancel a magnetic flux of a permanent magnet incorporated in the yoke. The present invention relates to a print head of a dot impact type printer that prints by driving a print wire fixed to an armature.

[0002]

2. Description of the Related Art Conventionally, an electromagnetic open type print head is well known as a print head for a dot impact printer.

FIG. 3 is a schematic side view in which a part of a conventional electromagnetic open type print head is cut away. As shown in FIG.
A core portion 51a is integrally projectingly provided on a yoke 51 having a ring-shaped permanent magnet 52 incorporated therein.
A coil 53 is wound around 1a. Also, the permanent magnet 5
A ring yoke 54 is fixed to the ring yoke 54, and the ring yoke 54 has one end extending to the center of the print head.
The other end of 6 is fixed via a spacer 55.
An armature 57 facing the end surface of the core portion 51a is fixed to one end of the leaf spring 56. Armature 5
A printing wire 59 is fixed to the wire 7 via an arm 58, and the tip end of the printing wire 59 has a wire guide 60.
It is slidably supported in a through hole formed in the.

In the non-printing state (the state shown in FIG. 3), the coil 53 is not excited, and the leaf spring 56 is elastically deformed by the magnetic attraction force of the permanent magnet 52 to cause the armature 57.
Are attracted to the core portion 51a of the yoke 51. When a current is applied to the coil 53 by a print signal from a drive circuit (not shown), the coil 53 is excited, and the magnetic flux of the core portion 51a is canceled by the action of the reverse magnetic field induced by the coil current. When the magnetic flux of the core portion 51a is canceled, the elastic energy stored by the elastic deformation of the leaf spring 56 is released, and the printing wire 59 separates from the core portion 51a. Therefore, the tip of the printing wire 59 is projected from the wire guide 60 and collides with a recording sheet (not shown) to perform printing. After printing, when the current of the coil 53 is cut off again, the armature 57 is attracted to the core portion 51a and pulled back to the original position.

[0005]

However, in the above-mentioned conventional print head, the collision of the print wire with the recording paper is performed by canceling the magnetic flux of the core portion. Therefore, in order to cancel this magnetic flux, the coil is There has been a problem that a large amount of current has to be applied and the power consumption of the print head increases.

On the other hand, the collision force of the printing wire on the recording paper, that is, the printing force has a great influence on the printing quality. If the printing force is small, the printing becomes thin and clear printing cannot be obtained. However, since the printing force is obtained only by releasing the elastic energy stored in the leaf spring, the printing wire is pushed back by the reaction force that the tip of the printing wire receives from the recording paper at the time of printing, and a sufficient printing force is obtained. There was also a problem that it could not be obtained.

It is an object of the present invention to provide a print head for a dot impact type printer, which requires a small amount of current to be passed through a coil and can obtain a sufficient printing force.

[0008]

To achieve the above object, the present invention is directed to a yoke in which a permanent magnet is incorporated and a core portion around which a coil is wound is projected, and one end of which is fixed to an outer peripheral portion of a print head. An armature fixed to the other end of the leaf spring, which is elastically deformed to magnetically attract the end surface of the core portion, and a printing wire fixed to one end of the armature, In a print head of a dot impact type printer in which a magnetic flux of the permanent magnet is canceled by driving an electric current through a coil to drive the print wire, a sub-yoke is integrally formed on the outer peripheral side of the print head from the core portion of the yoke. And the other end of the armature is located at a portion facing the end surface of the sub-yoke.

[0009]

In the present invention constructed as described above, the sub-yoke is integrally projected from the core portion to the outer peripheral side of the print head, and the other end portion of the armature is located at a portion facing the end surface of the sub-yoke. By doing so, the magnetic flux generated by the permanent magnet is divided into the core portion and the sub-yoke. Therefore, the magnetic flux in the core portion is smaller than that in the case without the sub-yoke. Further, when a current is passed through the coil to cancel the magnetic flux in the core portion, the magnetic flux in the core portion escapes to the sub-yoke and the magnetic flux in the core portion becomes smaller, so that the current flowing in the coil can be small. Moreover, since the armature is magnetically attracted to the core portion and the sub-yoke, the magnetic attraction force of the armature does not become weak.

Further, by supplying an electric current to the coil, the magnetic flux in the core portion is canceled and the elastic energy stored in the leaf spring is released to drive the print wire, and the tip of the print wire collides with the recording paper to print. Is done. At this time, since magnetic flux is generated by the permanent magnet in the sub-yoke, the other end of the armature tends to be magnetically attracted to the sub-yoke. For this reason, a force is exerted on the armature in the direction in which the printing wire is projected from the wire guide, and a large printing force is obtained.

[0011]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a partially cutaway schematic side view of an embodiment of the present invention. As shown in FIG. 1, a yoke 1 having a ring-shaped permanent magnet 2 incorporated therein has a core portion 1a,
A sub-yoke 1b located on the outer peripheral side of the print head with respect to the core portion 1a is integrally projected with a space therebetween, and a coil 3 connected to a drive circuit (not shown) is wound around the core portion 1a. It has been. A ring yoke 4 is fixed to the permanent magnet 2, and the ring yoke 4 has a spacer 5 at the other end of a leaf spring 6 having one end extending toward the center of the print head.
Is fixed through. One end of the armature 7 whose one end faces the end face of the core portion 1a and whose other end faces the end face of the sub-yoke 1b is fixed to one end of the leaf spring 6. Further, a print wire 9 is fixed to one end of the armature 7 via an arm 8,
The tip of the printing wire 9 is inserted into a through hole formed in the wire guide 10.

Next, the operation of this embodiment will be described with reference to FIGS. 1 and 2.

First, in the non-printing state shown in FIG. 1, no current is passed through the coil 3 and the coil 3 is not excited. Therefore, the armature 7 is attracted to the core portion 1a and the sub-yoke 1b by elastically deforming the leaf spring 6 due to the magnetic attraction force of the permanent magnet 2. At this time, elastic energy due to elastic deformation is stored in the leaf spring 6.

At the time of printing, a current is applied to the coil 3 by a print signal from a drive circuit (not shown). Coil 3
When a current is applied to the coil 3, the coil 3 is excited, and the magnetic flux of the core portion 1a is canceled by the action of the reverse magnetic field induced by the coil current. When the magnetic flux of the core portion 1a is canceled,
As shown in, the elastic energy stored in the leaf spring 6 is released. Due to the restoring force of the leaf spring 6 at this time, the armature 7 vigorously separates from the core portion 1a. As a result, the tip of the printing wire 9 is projected from the wire guide 10 and collides with a recording sheet (not shown) to perform printing.

At this time, since the yoke 1 is provided with the sub-yoke 1b, the magnetic flux generated by the permanent magnet 2 is generated by the core portion 1.
a and the sub-yoke 1b. Therefore, the core part 1
The magnetic flux generated in a is smaller than that without the sub-yoke 1b. Further, when a current is passed through the coil 3 to cancel the magnetic flux of the core portion 1a, the magnetic flux of the core portion 1a escapes to the sub-yoke 1b, so that the coil for canceling the magnetic flux of the core portion 1a is canceled as compared with the conventional print head. Three
The current flowing to the device can be small, and the power consumption of the print head can be reduced. Further, when the print wire 9 is projected and its tip collides with the recording paper, the print wire 9 receives a reaction force from the recording paper and pushes back the print wire 9, so that the armature 7 receives a moment in the direction of arrow A in the figure. work. However, the magnetic attraction force of the permanent magnet 2 acts on the sub-yoke 1b, the armature 7 is attracted by the sub-yoke 1b, and a moment in the direction of the arrow B in the figure acts. As a result, a force is exerted on the printing wire 9 in the direction in which the tip portion thereof is projected from the wire guide 10, and a large printing force is obtained as compared with the case without the sub-yoke 1b.

After printing, when the coil 3 current is cut off again, the armature 7 is attracted by the core portion 1a and the sub-yoke 1b and pulled back to its original position.

A desired print pattern is printed by repeating the above-described operation at high speed according to the print pattern.

[0019]

As described above, according to the present invention, the sub-yoke is integrally projectingly provided on the outer peripheral side of the print head from the core portion of the yoke, and the other end of the armature is provided at a portion facing the end surface of the sub-yoke. By positioning it, the current flowing through the coil for canceling the magnetic flux of the core portion can be small, and the power consumption of the print head can be reduced.

Further, by making the other end of the armature face the end surface of the sub-yoke, even if the print wire is pushed back by the reaction force when the print wire collides with the recording paper, the print wire is still attached to the armature. Since a force is exerted in the direction of protruding from the guide, a larger printing force can be obtained as compared with the conventional print head.

[Brief description of drawings]

FIG. 1 is a partially cutaway schematic side view of an embodiment of a print head of a dot impact type printer of the present invention.

FIG. 2 is a diagram showing a state of the print head shown in FIG. 1 during printing.

FIG. 3 is a schematic side view in which a part of a print head of a conventional dot impact printer is cut away.

[Explanation of symbols]

 1 yoke 1a core part 1b sub-yoke 2 permanent magnet 3 coil 4 ring yoke 5 spacer 6 leaf spring 7 armature 8 arm 9 printing wire 10 wire guide

Claims (1)

[Claims] 1. A yoke in which a permanent magnet is incorporated and a core portion around which a coil is wound is projected, and one end is fixed to the other end of a leaf spring fixed to the outer peripheral portion of the print head. It has an armature that elastically deforms a spring and is magnetically attracted to the end surface of the core portion, and a print wire fixed to one end portion of the armature, and cancels the magnetic flux of the permanent magnet by passing an electric current through the coil. In a print head of a dot impact type printer that drives the print wire, a sub-yoke is integrally projectingly provided on an outer peripheral side of the print head from the core portion of the yoke, and the other end portion of the armature is A print head for a dot impact type printer, characterized in that it is located at a portion facing the end face of the sub-yoke.