JPH06104363B2 - Printhead armature - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printhead armature, and more particularly to a printhead armature constituting a wire dot printer.

[Conventional technology]

Conventionally, the print head in this type of wire dot printer is as shown in FIG.

FIG. 3 is a side sectional view of a print head showing a conventional example.

As shown in FIG. 3, in the conventional print head, the yoke 13, the permanent magnet 14, and the armature 15 are held by the frame 16. Inside the frame 16, there are intermediate guides 17 and 18, and a tip guide 19 is formed at the tip thereof. The armature 15 described above includes a leaf spring 20, an arm 22 of the armature block 21, and a print wire 23.

Normally, the armature 15 is yoked by the magnetic force of the permanent magnet 14.
It is attracted to the tip of 13, and the leaf spring 20 is bent. Therefore, the coil 24 wound around a part of the yoke 13
When the power is turned on, the magnetic force of the permanent magnet 14 is canceled, so
The armature 15 is released from the yoke 13, and the force of the leaf spring 20 moves the print wire 23 to the left in the drawing via the arm 22. The printing wire 23 is guided by the intermediate guides 17 and 18 and the tip guide 19 which are positioned on the frame 16, and prints dots at predetermined positions.

Next, the structure of the armature will be described.

FIG. 4 is a side view of the entire armature shown in FIG.

As shown in FIG. 4, one end of a leaf spring 20 is fixed to this armature, and the armature block 12 is attached to the free end side thereof.
Are joined by laser welding. In addition, a slit is provided at an end of the armature block 21 that is not the leaf spring joint end, and a slit is provided perpendicularly to the leaf spring joint surface, and the arm 22 is fitted into this slit and joined by brazing.
The print wire 23 is attached to the end of the arm 22 that is not the joining end.
However, they are joined by brazing.

Next, the stress distribution of the arm when the armature operates will be described.

As shown in FIG. 4, when printing is performed by the armature print wire 23, a platen, paper,
Since the reaction force 25 from the ink ribbon acts, the moment force 26 acts on the arm 22. At this time, the part where the stress becomes high becomes the part of the stress distribution regions 27, 28, 29 of the arm 22. A tensile stress mainly acts on the stress distribution regions 27 and 28, and a compressive stress acts on the stress distribution region 29. In particular, the region with the highest stress is the region 28, but since it is inside the arm 22, it does not serve as the starting point of arm breakage, and the region 29 with the next highest stress breaks.

Conventionally, as a measure against this arm damage, the plate thickness of the arm 22 is increased to increase the strength.

[Problems to be Solved by the Invention]

The conventional armature of the print head described above has a drawback that stress is concentrated on the joint portion between the arm and the armature block, and the arm is damaged. Further, when the plate thickness of the arm is increased to increase the strength of the arm, the mass of the armature is increased, so that the natural frequency of the armature is lowered and the speeding up of the print head is hindered.

It is an object of the present invention to provide an armature of a print head that realizes such a breakage of the arm and speeding up of the print head.

[Means for Solving the Problems]

An armature of a print head according to the present invention is joined to a leaf spring of a wire dot print head and a free end of the leaf spring, and is perpendicular to a leaf spring joint surface at an end opposite to a joint end of the leaf spring. An armature block, comprising: an armature block provided with a slit; an arm fitted to the slit and joined by brazing; and a print wire joined to a free end of the arm, the armature block comprising: Is formed by providing a step portion on a surface substantially perpendicular to the leaf spring joint surface on which the slit is provided.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

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

As shown in FIG. 1, in this embodiment, one end (not shown) of the leaf spring 1 is fixed, and the armature block 2 is joined to the free end side by laser welding. A step portion 3 is provided on a surface of the armature block 2 different from the leaf spring joint end on a surface substantially perpendicular to the leaf spring joint surface. Further, slits 4 are provided perpendicularly to the plane spring joint surface and the plane spring joint surface. An arm 5 is fitted into the slit 4 and joined by brazing. A print wire 6 is brazed to one end of the arm 5 which is not a joint end.

Next, the stress distribution of the arm 5 when the armature operates will be described with reference to FIG.

FIG. 2 is a side view of the entire armature shown in FIG.

As shown in FIG. 2, when printing is performed by the armature of the print head, a reaction force 7 from a platen, a sheet, and an ink ribbon (not shown) acts on the print wire 6 and a moment force 8 is applied to the arm 5. Works. At this time,
The part where the stress is high is the stress distribution area 9, 10, 11,
12 parts. A tensile stress mainly acts on the stress distribution regions 9 and 10, and a compressive stress acts on the stress distribution regions 11 and 12.

It should be noted here that, as in the present embodiment, by providing the step portion 3 in the armature block 2, the compressive stress concentrated in the stress distribution area 29 of the conventional arm 5 is reduced to the stress distribution area 11 and It is distributed in 12 parts. As a result of actually performing the stress calculation, the stress in the stress distribution region 12 of the arm 5 was halved, and the arm breakage accident was also solved by the result of the trial experiment.

〔The invention's effect〕

As described above, the armature of the print head according to the present invention can disperse the stress acting on the arm joint by providing the stepped portion at the arm joint of the armature block. There is an effect that the reliability of the armature can be improved and the printing speed can be increased without increasing the mass.

[Brief description of drawings]

FIG. 1 is a perspective view of an armature of a print head showing an embodiment of the present invention, FIG. 2 is a side view of the entire armature shown in FIG. 1, and FIG. 3 is a side sectional view of a print head showing an example of the prior art. 4 is a side view of the entire armature shown in FIG. 1 ... Leaf spring, 2 ... Armature block, 3 ... Step, 4 ... Slit, 5 ... Arm, 6 ... Printing wire, 7 ... Reaction force, 8 ... Moment force, 9-12 ... … Stress distribution area.

Claims (1)

[Claims] 1. A leaf spring of a wire dot printing head is joined to a free end of the leaf spring, and a slit is provided at an end portion opposite to a joining end of the leaf spring, the slit being perpendicular to a leaf spring joining surface. An armature block, an arm fitted to the slit and joined by brazing, and a print wire joined to the free end of the arm in a printhead armature, the slit of the armature block being provided. An armature for a print head, which is characterized in that a step portion is provided on a surface substantially perpendicular to the leaf spring joint surface.