JPH05201033A - Printing head for dot impact type printer - Google Patents

Abstract

PURPOSE:To prevent an arm from being damaged, etc., due to a high frequency vibration by providing an arm attraction yoke which attracts an arm by magnetic force evenly for the right and left from the side surface, on a dot impact type printing head. CONSTITUTION:When current flows on a coil, since the magnetic force by a permanent magnet is negated, a distortion energy which is accumulated on a leaf spring 4 is released, and a printing wire which is attached to an arm 1 is driven to perform a printing. When the current on the coil is shut off after the printing, an armature 3 is drawn by the magnetic force of the magnet again, and the printing wire is pulled back to the original position. Since this series of motions is repeated at a high speed at the time of printing, a vibration of a higher frequency other than the driving frequency is generated on the arm 1 which connects the armature 3 and printing wire. In order to prevent a bad influence due to this from happening, an arm attraction yoke 7, which attracts the side surface of the arm 1, is attached to suppress this vibration.

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 an electromagnetic type print head including a permanent magnet.

[0002]

2. Description of the Related Art A conventional print head has a leaf spring 4 having a permanent magnet 5, a yoke 8, a coil 6, an arm 1 for driving a print wire 2 and an armature 3 as shown in FIG.

Next, the operation will be described. When the coil 6 is not energized, the armature 3 is attracted to the yoke 8 by the magnetic force of the permanent magnet 5. At this time, the strain energy is stored in the leaf spring 4. When a current is passed through the coil 6, the magnetic force of the permanent magnet 5 is canceled and the distortion energy stored in the leaf spring 4 drives the printing wire 2. When the energization of the coil 6 is stopped after printing, the armature 3 is attracted to the yoke 8 again by the magnetic force of the permanent magnet 5 and is returned to the original position.

[0004]

Since the conventional print head is driven at a high speed, a large vibration is generated. In particular, the arm part for the print wire is easily affected by this vibration and causes vibration of higher frequencies other than the drive frequency, which causes damage to the arm and malfunction of the wire for the print wire. There is.

An object of the present invention is to provide a print head of a dot impact type printer in which arm vibration is reduced by attracting the arm from the side surface by magnetic force.

[0006]

SUMMARY OF THE INVENTION The dot impact type print head of the present invention is a print wire, a print wire for a print wire, by controlling a magnetic circuit including a permanent magnet and a coil wound in a direction to cancel the magnetic flux. In the dot impact type print head that performs printing by releasing the strain energy of the leaf spring equipped with the arm and armature,
An arm suction yoke that uniformly attracts the arm from the side by the magnetic force is provided.

[0007]

The arm suction yoke is attached so as to sandwich the arm of the print head from the side surface, and attracts the arm evenly to the left and right by the magnetic force of the yoke. Thereby, the vibration of the arm is suppressed.

[0008]

The present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a print head according to an embodiment of the present invention. The difference from the prior art is that it has a yoke 7 for arm suction attached in contact with the yoke, and other configurations are the same as the prior art.

Next, the operation of the embodiment will be described. When no current flows through the coil 6, the magnetic force of the permanent magnet 5 attracts the armature 3 to the yoke 8. At this time, the leaf spring 4 is bent and strain energy is stored. When a current flows through the coil 6, the magnetic force of the permanent magnet 5 is canceled out, so the strain energy stored in the leaf spring 4 is released, and the printing wire attached to the arm is driven to perform printing. When the coil 6 is turned off after printing, the armature 3 is again attracted by the magnetic force of the permanent magnet 5, and the printing wire 2 is pulled back to its original position.
During actual printing, this series of operations is repeated at high speed. Therefore, the arm 1 connecting the armature and the printing wire 2 is vibrated at a higher frequency than the driving frequency. Arm 1 to prevent adverse effects
This vibration is suppressed by attaching an arm suction yoke 7 that sucks the side surface of the arm. The function will be described with reference to FIG. FIG. 2 is a simplified diagram in which the cross section in FIG. 1A-A is enlarged.
Two directions of (a) and (b) in FIG. 2 can be considered for high-order frequency vibration of the arm 1. In either case, it may cause damage to the arm or malfunction of the armature system. First, regarding the vibration in the (a) direction, FIG.
As described above, it can be suppressed by pulling the arm side surface to the left and right (x direction in the drawing) by the magnetic force of the permanent magnet 5. Next, regarding the vibration in the direction of (b), FIG.
As shown in (3), since the component of the magnetic force received by the arm includes the component in the y direction, the vibration in the (b) direction is suppressed.

[0010]

As described above, according to the present invention, since the yoke for attracting the arm from the side surface is attached, the vibration of the arm can be reduced, and the damage of the arm due to the high frequency vibration and the malfunction of the printing wire can be prevented. Has the effect of

[Brief description of drawings]

FIG. 1 is a side sectional view of a print head according to an embodiment of the present invention.

2A and 2B are sectional views taken along the line AA of FIG. 1 for explaining the operation of the arm suction yoke.

FIG. 3 is a perspective view of a print head according to an embodiment of the present invention.

FIG. 4 is a side sectional view of a conventional print head.

[Explanation of symbols]

 1 arm 2 printing wire 3 armature 4 leaf spring 5 permanent magnet 6 coil 7 arm suction yoke 8 yoke

Claims (1)

[Claims] 1. A magnetic circuit including a permanent magnet and a coil wound in a direction for canceling the magnetic flux thereof is controlled,
In a dot impact type print head for performing printing by releasing strain energy of a leaf spring having a print wire, a print wire arm, and an armature, an arm suction yoke that uniformly attracts the arm from the side by a magnetic force. A print head comprising: