JPH09187972A - Wire dot print head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve printing quality in a wire dot print head wherein a distance from a platen differs dependent on printing wire. SOLUTION: A protruded piece 7c is formed on a spacer 7 to be arranged at an opposite side of an armature 11 with respect to a plate spring 8. The protruded piece 7c is arranged at an opposite side of a fixing section 8d of the plate spring 8 to be fixed to the armature 11. A length from the head end of the protruded piece 7c to a core 13 is made to be short at a part corresponding to a printing wire 12 at the end part and is made to be long at a part corresponding to the printing wire 12 at the central part. Thus, a turning angle of the armature 11 at the time of suction corresponding to the printing wire 12 at the end part becomes large and its stroke also becomes large.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire dot print head used in an impact printer.

[0002]

2. Description of the Related Art Conventionally, in an impact printer, an armature is fixed to the free end of a cantilevered plate spring radially arranged toward the center, and a printing wire is provided at the tip of the armature, and a permanent magnet is provided. Magnetic flux attracts the armature together with the leaf spring to the core to bend the leaf spring, and when printing, demagnetizes the magnetic flux of the permanent magnet to release the leaf spring and rotate the armature. There is one having a wire dot print head that is projected and hits a print sheet through an ink ribbon. The printing paper is positively conveyed so as to be wound around a cylindrical platen, and is positioned between the print head and the platen together with the ink ribbon. When the wire protruding from the print head hits the platen via the ink ribbon and the printing paper, the ink of the ink ribbon adheres to the paper and printing is performed.

[0003]

The platen around which the printing paper is wound is usually in the shape of a cylinder so that the paper can be conveyed smoothly. A plurality of print wires protruding in the platen direction are arranged at the tip of the print head in a direction orthogonal to the axial direction of the platen. Therefore, in the non-printed state, the print wire located at the center is closest to the platen, is gradually separated from the platen toward the end, and the print wire located at the end is farthest from the platen. Therefore, when printing, the print wire at the end requires a larger stroke to the platen than the print wire at the center. For example, if the gap between the print wire and the platen is large, the print wire at the end will reach the platen. However, there was a problem that printing defects occurred.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is directed to attracting an armature by the magnetic flux of a permanent magnet, biasing a cantilevered plate spring fixed to the armature, and winding the plate spring around the core. By energizing the generated coil, the magnetic flux of the permanent magnet is canceled and the armature is released. It is characterized in that the rotating armature has a larger stroke for the print wire arranged at the end of the plurality of print wires and smaller for the print wire arranged at the center.

According to the present invention having the above structure, the armature corresponding to the print wire at the end has a large stroke during suction. Along with this, the amount of bending of the leaf spring that fixes the armature also increases, and the strain energy increases. Therefore, when the armature is released from the core during printing, the stroke of the printing wire increases.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. Elements common to the drawings are assigned the same reference numerals. FIG. 1 is an exploded perspective view showing a main part of a first embodiment of the present invention, and FIG. 2 is a partial sectional view showing a wire dot print head of the embodiment. First, the configuration of the entire print head will be described with reference to FIG.

In FIG. 2, a first yoke 4, a permanent magnet 5, a magnet yoke 6, a spacer 7, a leaf spring 8 and an armature yoke 9 are sequentially laminated on a base plate 3, and a guide frame 1 is further mounted on the armature yoke 9. It is stacked. The cap 2 is attached to the lower surface of the base plate 3. These members are fixed by the clamp 10. An armature 11 is fixed to the free end of a cantilevered leaf spring 8 arranged radially toward the center, and a print wire 12 is fixed to the tip of the armature 11. The tip of the printing wire 12 is projected toward the platen 20 by the guide 1a of the guide frame 1. The first yoke 4, the permanent magnet 5, the magnet yoke 6, the spacer 7, the leaf spring 8 and the armature yoke 9 are each provided in an annular shape,
A core 13 is erected on the base plate 3 inside thereof. The core 13 is provided so as to face each armature 11, and the coil 14 is wound around and the bobbin 17 is mounted. The coil 14 is a space sheet 1 for positioning.
It is connected to the printed circuit board 16 fixed to the base plate 3 via 5.

FIG. 1 shows a main part corresponding to the print wire at the end. In FIG. 1, the leaf spring 8 includes two spring effective portions 8a, 8b, a front end side fixing portion 8c and a rear end side fixing portion 8d for fixing the armature 11, and a base end side for the armature yoke 9 and the spacer 7. It has an outer edge portion 8e that is fixed. In addition, the x mark shown in the figure indicates a fixed portion. The armature 11 has a tip end fixing portion 8c of the leaf spring 8.
A fixing portion 11a fixed to the leaf spring 8 while straddling the rear end fixing portion 8d and a lever portion 11b extending from the fixing portion 11a toward the center of the print head and fixing the print wire 12 to the front end portion. Composed of and.

In the spacer 7, the spring effective portion 8 of the leaf spring 8 is
A tongue-shaped protruding piece 7c is formed between the portions 7a and 7b facing the base end portions of a and 8b. The protruding piece 7c is a leaf spring 8
Provided so as not to interfere with the spring effective portions 8a and 8b of
The tip 7cc of the protruding piece 7c is located closer to the core 13 than the center of rotation of the armature 11 described later. This protruding piece 7c
The length of the core in the direction of the core 13 is the largest corresponding to the print wire located at the end, and gradually decreases toward the print wire in the center, and the protruding piece corresponding to the print wire in the center is formed. The length of 7c in the direction of the core 13 is the shortest.

The magnet yoke 6 is laminated between the permanent magnet 5 and the outer edge portion 7d of the spacer 7, and the protruding piece 6 is provided inside.
a is formed. The protruding piece 6a is located below the protruding piece 7c of the spacer 7 and prevents the protruding piece 7c from bending when the armature 11 is sucked by the core 13.
I support. Therefore, the protruding piece 6a is formed to have the same length as the protruding piece 7c. Also, the armature yoke 9
It has a groove 9a for receiving the armature 11 with a minute gap maintained, and the outer edge 9b is fixed to the outer edge 8e of the leaf spring 8.

FIG. 3 is a side view showing an essential part of the first embodiment, and shows a portion of the end portion corresponding to the print wire (referred to as the end portion side). FIG. 4 is a side view showing an essential part of the first embodiment, and shows a portion corresponding to the print wire in the central portion (referred to as the central portion side). Both figures show the state where the armature is sucked to the core side.

In both figures, the length from the tip of the protruding piece 7c of the spacer 7 to the core 13 is l1 <m1 where l1 is on the end side and m1 is on the center side. The tip of the projecting piece 7c on the end side is located closer to the core 13 side than the rotation center A at the time of suction and release of the armature 11, and on the end side, the tip of the projecting piece 7c is on the armature 11 and the leaf spring 8. Will be the compulsory fulcrum of. On the other hand, the tip of the projecting piece 7c on the center side is at the same position as the rotation center A when the armature 11 is sucked and released. When the rotation angle of the armature 11 on the end side is α1 and the rotation angle of the armature 11 on the center side is β1, α1> β1. Therefore, assuming that the stroke of the tip of the armature 11 on the end side is L1 and the stroke of the tip of the armature 11 on the center side is M1, L1> M1. That is, the armature 1 on the end side
No. 1 has a larger stroke. Armature 11 corresponding to each print wire located between the end side and the center side
The stroke is set according to the difference in stroke depending on the shape of the platen.

Next, the operation will be described. In the non-printing state, the armature 11 is attracted to the core 13 by the magnetic flux of the permanent magnet 5. At this time, the leaf spring 8 is also attracted at the same time, and strain energy is accumulated in the leaf spring 8. Here, the strain energy of the leaf spring 8 on the end side is larger than the strain energy of the leaf spring 8 on the center side. When the coil corresponding to the print data is energized in this state, the magnetic flux of the permanent magnet is canceled and the armature 11 is released.

At this time, the armature 11 on the end side is
Since the strain energy of the leaf spring 8 fixed to this is large, the printing wire 12 is projected with a large stroke.
Therefore, even when there is a large gap between the tip of the printing wire at the end and the platen at the time of non-printing, the printing wire at the end can reach the platen and good printing can be performed.

Further, in the first embodiment, as shown in FIG. 3, the tip end 7cc of the protruding portion 7c of the spacer 7 serving as the fulcrum of rotation of the armature 11 is fixed to the rear end side fixed portion 8d of the leaf spring 8.
, The rotation of the armature 11 due to suction and release is stabilized, and the printing quality is improved.

Next, a second embodiment of the present invention will be described. FIG. 5 is an exploded perspective view showing a main part of the second embodiment. In FIG. 5, the leaf spring 8 has the same shape as that of the first embodiment. The spacer 21 includes a base end portion 21a corresponding to the base end portions of the spring effective portions 8a and 8b of the leaf spring 8,
21b and an outer edge portion 21c laminated and fixed to the outer edge portion 8e of the leaf spring 8 and the magnet yoke 22. Both of the base end portions 21a and 21b have a protruding shape with respect to the intermediate portion 21d located between the base end portion 21a and the base end portion 21b, and the length of the protrusion is from the central portion side to the end portion. It gradually becomes longer as it goes to the club side. That is, it is close to the core 13 side.

The magnet yoke 22 is laminated and fixed by the outer edge portion 21c of the spacer 21 and the permanent magnet 5, and the inner end portion thereof has the same shape as the permanent magnet 5 and the first yoke 4, and is constant with the core 13. Keeps the intervals. Other configurations are the same as those of the first embodiment.

FIG. 6 is a side view showing the main part of the second embodiment, showing the end side. FIG. 7 is a side view showing the main part of the second embodiment, showing the central part side. Both figures show the state where the armature is sucked to the core side.

In both figures, the base end portion 21 of the spacer 21 is shown.
The length from the tips of a and 21b to the core 13 is 12 <m2, where 12 is the end side and m2 is the center side. When the rotation angle of the armature 11 on the end side is α2 and the rotation angle of the armature 11 on the center side is β2, α2
> Β2. Therefore, the armature 11 on the end side
The stroke of the tip is L2, the armature 11 on the center side
If the stroke of the tip is M2, then L2> M2.
That is, the end armature 11 has a larger stroke. The stroke of the armature 11 corresponding to each print wire located between the end side and the center side is set according to the difference in stroke due to the shape of the platen.

Next, the operation will be described. In the non-printing state, the armature 11 is attracted to the core 13 by the magnetic flux of the permanent magnet 5. At this time, the leaf spring 8 is also attracted at the same time, and strain energy is accumulated in the leaf spring 8. Here, the strain energy of the leaf spring 8 on the end side is larger than the strain energy of the leaf spring 8 on the center side. When the coil corresponding to the print data is energized in this state, the magnetic flux of the permanent magnet is canceled and the armature 11 is released.

At this time, the armature 11 on the end side is
Since the strain energy of the leaf spring 8 fixed to this is large, the printing wire 12 is projected with a large stroke.
Therefore, even when there is a large gap between the tip of the printing wire at the end and the platen at the time of non-printing, the printing wire at the end can reach the platen and good printing can be performed. Further, since the spring constants of the spring effective portions 8a and 8b of the leaf spring 8 increase as the tips of the base end portions 21a and 21b of the spacer 21 approach the core 13, the flight time of the printing wire, that is, the rotation of the armature 11 is increased. Time is getting shorter,
The repeatability of the armature 11 operation is improved.

[0022]

As described above in detail, according to the present invention, the armature corresponding to the print wire at the end has a large stroke during suction. Along with this, the amount of bending of the leaf spring that fixes the armature also increases, and the strain energy increases. Therefore, when the armature is released from the core during printing, the stroke of the printing wire increases.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a main part of a first embodiment.

FIG. 2 is a partial cross-sectional view showing the wire dot print head according to the embodiment.

FIG. 3 is a side view showing a main part of the first embodiment.

FIG. 4 is a side view showing a main part of the first embodiment.

FIG. 5 is an exploded perspective view showing a main part of the second embodiment.

FIG. 6 is a side view showing a main part of the second embodiment.

FIG. 7 is a side view showing a main part of the second embodiment.

[Explanation of symbols]

 7 Spacer 7a Projecting Piece 8 Leaf Spring 11 Armature 12 Printing Wire 13 Core 20 Platen

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takanori Mimura 4-11-11 Shibaura 4-chome, Minato-ku, Tokyo In the Oki data of the stock company

Claims (4)

[Claims] 1. A magnetic flux of a permanent magnet attracts an armature to bias a cantilevered plate spring fixed to the armature, and a coil wound around a core is energized to cancel the magnetic flux of the permanent magnet. In a wire dot print head that releases the armature and projects multiple print wires fixed to the tip of the armature for printing, the stroke of the armature rotated by the attraction of the magnetic flux of the permanent magnet is set to the end of the multiple print wires. A wire dot print head characterized in that it is made larger as it becomes a print wire arranged in a central part and made smaller as it becomes a print wire arranged in a central part. 2. The wire dot print head according to claim 1, wherein the size of the stroke is changed by changing a distance between a rotation fulcrum of an armature and the core. 3. The wire according to claim 2, wherein a distance between a rotation fulcrum of the armature and the core is changed by changing a length of a protruding piece formed by a spacer arranged on a bending side of the leaf spring. Dot print head. 4. The wire dot print head according to claim 1, wherein the stroke size is changed by changing the length of the fixed end of the leaf spring.