JPH0725040A - Dot impact type print head - Google Patents

Abstract

PURPOSE:To rotate a print head smoothly and make printing on a number of copying papers easy. CONSTITUTION:A rotational supporting point 5 is provided at a yoke core 9 and a plate spring 6 is attached at a first armature 4a and a second armature 4b with boundary at the rotational supporting point 5 so as to energize an armature 4 in the printing direction, so that an armature system including a print wire 1 and an arm 3 always rotates smoothly with center at the rotational supporting point 5. At the same time, the second armature 4b is always attracted magnetically by an auxiliary yoke core 7 which is extended toward the armature 4b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dot impact type print head, and more particularly to a dot impact type print head including a permanent magnet and a leaf spring.

[0002]

2. Description of the Related Art An example of a dot impact type print head which has been widely used in the past is shown in FIG. As shown in FIG. 4, the conventional dot impact type print head includes a permanent magnet 10, a yoke core 9, a coil 8 for demagnetizing a magnetic flux flowing through the yoke core 9, a printing wire 1, and a printing wire 1. It has a guide portion 2 for assisting the operation, an arm 3 for driving the print wire 1, and a leaf spring 18 having an armature 17.

Next, the operation of the dot impact type print head shown in FIG. 4 will be described. When the coil 8 is not energized, the armature 17 is attracted to the yoke core 9 by the magnetic force of the permanent magnet 10. At this time, the leaf spring 18
Is deflected and strain energy is stored. When the coil 8 is energized, the magnetic flux flowing in the yoke core 9 is demagnetized,
Since the force attracting the armature 17 to the yoke core 9 is reduced, the strain energy stored in the leaf spring 18 is released, and the printing wire 1 passes through the armature 17 and the arm 3 and the C shown in FIG. Driven in the direction of. At this time, the printing wire 1 makes a striking motion with respect to the paper surface on the platen via the ink ribbon to perform printing. When the coil 8 is de-energized again after printing, the armature 17 is again attracted to the yoke core 9 and returns to the initial state. In actual printing, this series of operations is repeated at high speed.

[0004]

In this conventional dot impact type print head, when the print wire and the platen collide, the leaf spring is bent by the inertial force of the armature 17 (hereinafter, this phenomenon is referred to as belly button). Therefore, the printing operation is adversely affected, and smooth rotational movement is not performed. Further, in this conventional mechanism, the strain energy of the leaf spring is almost eliminated during printing, and printing is performed by the printing wire 1 and the arm 3.
Since printing is performed only by the inertial force of the armature system including the armature 17, there is a problem that it is not suitable for printing multi-copy paper.

Therefore, at present, in order to reduce the abdominal flare, as shown in FIG.
A cross pin 15 may be added at a right angle to. However, with this configuration, although the deflection of the leaf spring due to the inertial force is reduced, the collision time between the printing wire and the platen is shortened, and the print density is reduced, which is further unsuitable for printing on multi-copy paper. It ’s getting worse,
It was a big problem.

Further, as shown in FIG. 6, as a print head for reducing the abdominal flare, for example, Japanese Unexamined Patent Publication No. 3-278.
There is a print head described in Japanese Patent No. 964, which has a rotation fulcrum inside the armature. This print head has the same basic structure as the print head shown in FIG. 4, but by providing a rotation fulcrum on the armature 21 in FIG. 6, the above-described series of printing operations is made into a smoother rotational movement.

However, in the mechanism shown in FIG. 6, it is possible to make the rotary motion smoother,
As in the case of using the cross pin (FIG. 5), the problem of being unsuitable for printing on multi-copy paper tends to be further aggravated.

[0008]

In order to achieve the above object, the power supply circuit of the present invention has a printing wire for applying an impact force to the paper surface on the platen for printing, a permanent magnet, and a U-shaped cross section. In a dot impact type print head which controls a magnetic circuit composed of a yoke and a coil wound in a direction to demagnetize a magnetic flux flowing in the yoke, releases strain energy accumulated in an elastic member and performs printing, The first armature joined to the end of the printing wire via the arm, the second armature connected to the first armature, and the printing direction between the first armature and the second armature. An armature having a notch provided on the opposite side, and a rotation fulcrum provided at a position for rotating the armature and facing the notch of the armature. And Kukoa one end fixed and the first
Of the armature and a leaf spring joined to the second armature. The leaf spring is joined to the armature at two points so that they are not on the same side with the rotation fulcrum as a boundary, and at these two points of joining. The armature is flexed to receive a load that rotates in the printing direction.

Further, the yoke core includes a sub-yoke core extending toward the second armature.

[0010]

The present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing an embodiment of the dot impact type print head of the present invention. FIG. 2 is a sectional view of the dot impact type print head of the present invention when the first armature portion is attracted to the yoke core. FIG. 3 is a sectional view of the dot impact type print head of the present invention when the yoke core is demagnetized. In FIGS. 1 to 3, reference numeral 1 is a print wire that applies an impact force to the paper surface on the platen via an ink ribbon to perform printing. An end of the print wire 1 is attached to one end of an arm 3, and an armature 4 is attached to the other end of the arm. The armature 4 includes a notch 13 formed on a facing surface of a yoke core 9, which will be described later, a first armature portion 4a provided at a position facing the yoke core 9 with the notch 13 interposed therebetween, and the first armature portion. 4a, and a second armature portion 4b provided at a position facing the sub-yoke core 7.

A base plate 11 having a substantially L-shaped cross section surrounds the armature 4 at one end of a U-shaped yoke 12 having a U-shaped cross section arranged on the surface of the armature 4 having the notch 13. It is connected. The permanent magnet 10 is sandwiched between the base plate 11 and the yoke 12, and a magnetic circuit is formed by the yoke 12, the base plate 11, the permanent magnet 10, and the like.

A yoke core 9 is provided at the other end of the yoke 12.
Extends toward the first armature portion 4a,
The yoke core 9 has a rotation fulcrum 5 at a position facing the notch 13 of the armature 4 for rotating the armature 4. A single leaf spring 6 having a cross-sectional shape that is a combination of a substantially U-shape and a single U-shape so as to smoothly perform this pivoting motion is provided with the rotation fulcrum 5 as a boundary and the first armature portion 4a and The second armature portion 4b is arranged so as to be joined at two points E and D. That is, the U-shaped part of the leaf spring is joined to the second armature part 4b, and the one-shaped part is joined so as to bias the first armature part 4a in the printing direction. Therefore, the joining portion E on the first armature portion 4a side is always urged in the direction opposite to the attraction force of the permanent magnet 10, and the joining portion D on the second armature portion 4b side is applied in the attraction force direction of the permanent magnet 10. Energize.

A coil 8 is wound around the yoke core 9. The coil 8 has a function of generating a magnetic flux in the opposite direction to the magnetic flux generated by the permanent magnet 10. Then, the sub-yoke core 7 is provided substantially at the center of the yoke core 9 and the permanent magnet 10. The end portion of the sub-yoke core 7 extends toward the second armature portion 4b and is magnetized by the permanent magnet 10. Here, the operation of the dot impact type print head of the present invention in this configuration will be described. 2 and 3 are cross-sectional views of a dot impact type print head according to an embodiment of the present invention, which shows operations performed during printing. First, when the coil 8 is not energized, the permanent magnet 10
Of the yoke core 9 due to the magnetic force of
Is adsorbed on the end face of. At this time, the leaf spring 6 joined to the first armature portion 4a is bent to store strain energy.

At this time, the armature 4 receives a force by the leaf spring 6 so as to rotate in the a direction around the rotation fulcrum 5 at the joint portions E and D in FIGS. 2 and 3, and in the second armature portion 4b. A magnetic attraction force from the sub-yoke core receives a force in the b direction.

If the sum of these two forces is F, then
The attraction force that the first armature portion 4a receives from the yoke core 9 is designed to be larger than F.
In addition, the print wire 1 is connected to the armature 4 via the arm 3.
It is stored inside the print head because it is linked to.

Next, when the coil 8 is energized, the magnetic flux flowing in the yoke core 9 is demagnetized, and the magnetic attraction force acting on the first armature portion 4a of the armature 4 is reduced, and the armature 4 is stored in the leaf spring 6. Direction in which strain energy is released,
That is, while rotating around the rotation fulcrum 5 in the direction a in FIG. 3, the joint E on the side of the second armature portion 4b operates so as to push the second armature portion 4b in the direction b in FIG. Therefore, the print wire 1 operates in the direction c in FIG. 3 and hits the paper surface through the ink ribbon to print dots. When the power supply to the coil 8 is cut off again, the magnetic flux flows through the yoke core 9 again, so that the first armature portion 4a is attracted by the yoke core 9 and pulled back to its original position.

In actual printing, this series of operations is repeated at high speed.

In this way, the yoke core 9 is provided with the rotation fulcrum 5, and the leaf spring 6 is provided with the armature 4 at two positions on the side of the rotation fulcrum 5 on the side of the first armature portion 4a and the side of the second armature portion 4b. When the armature system including the printing wire 1 and the arm 3 is attached so as to be biased in the a and b directions, the armature system always rotates smoothly around the rotation fulcrum 5. At the same time, the second armature part 4b is
The sub-yoke core 7 extending toward this is always magnetically attracted. Therefore, not only the inertial force of the armature 4 but also the magnetic attraction force is added at the time of printing, which facilitates printing on multi-copy paper.

[0019]

As described above, according to the present invention, the armature is provided with the rotation fulcrum, the leaf springs are arranged so as to be joined at two points so as not to be on the same side with the rotation fulcrum as a boundary, and the armature is printed. Since the sub-yoke core that attaches the load that rotates in the direction is received at these two points and the armature always attracts the armature magnetically in the printing direction, the armature system including the printing wire and the arm makes a smooth rotational movement. Printing on multi-copy paper can be facilitated.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a dot impact type print head of the present invention.

FIG. 2 is a cross-sectional view of the dot impact type print head according to the embodiment of the present invention when the first armature portion is attracted to the yoke core.

FIG. 3 is a sectional view of a dot impact type print head according to an embodiment of the present invention when a yoke core is demagnetized.

FIG. 4 is a sectional view of a conventional print head of this type.

FIG. 5 is a sectional view of a conventional print head of this type.

FIG. 6 is a sectional view of a conventional print head of this type.

[Explanation of symbols]

 1 printing wire 2 guide 3 arm 4 armature 4a first armature part 4b second armature part 5 rotation fulcrum 6 leaf spring 7 sub-yoke core 8 coil 9 yoke core 10 permanent magnet 11 base plate 12 yoke 13 notch

Claims (2)

[Claims] 1. A printing wire for applying an impact force to a paper surface of a platen for printing, a permanent magnet, a yoke having a U-shaped cross section, and a winding wire wound so as to demagnetize a magnetic flux flowing through the yoke. A dot impact type print head which controls a magnetic circuit composed of a coil to release strain energy stored in an elastic member to perform printing. A first impact type print head is joined to an end of the print wire via an arm.
An armature, a second armature connected to the first armature, and an armature provided between the first armature and the second armature on a side opposite to a printing direction, A yoke core that rotates the armature and has a rotation fulcrum provided at a position facing the notch of the armature, a plate having one end fixed and joined to the first armature and the second armature. A leaf spring, the leaf spring being joined to the armature at two points so as not to be on the same side with the rotation fulcrum of the yoke core as a boundary, and the armature in the printing direction at the two points of joining. A dot impact type print head characterized by being bent so as to receive a rotating load. 2. The dot impact print head according to claim 1, wherein the yoke core is provided with a sub-yoke core extending toward the second armature.