JP2534169Y2 - Impact dot head - Google Patents

Description

[Detailed description of the invention]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a print head for an impact dot printer, and more particularly, to a lever for driving a print wire.

[Prior art]

2. Description of the Related Art An impact dot head for performing impact printing on a print medium via an ink ribbon by selectively projecting a print wire has been widely known. As a means for driving the printing wire, the armature is selectively attracted to the core by a lever which is engaged with the printing wire at one end, has an armature, and is rotatably supported with the other end as a fulcrum. In general, the printing wire is operated by enlarging the rotational displacement caused by the rotation. FIG. 7 is a partial explanatory view showing the vicinity of the lever rotation fulcrum of such an impact dot head. The fulcrum 3 projecting like a hook is attached to the frame 8
And a lever 1 is rotatably supported by a fulcrum pressing spring 2 against the upper surface a of the fulcrum and the side wall surface b of the fulcrum receiving member 5.
When a force for attracting the armature 6 to the core 9 is electromagnetically generated, the lever 1 is rotated in the direction of the arrow about the fulcrum 3 as a rotation center, so that the lever 1 on the opposite side to the fulcrum 3 is not shown. Printing is performed by displacing the printing wire engaged with the end. The fulcrum upper end face 4 of the lever 1 with which the fulcrum pressing spring 2 abuts is formed in an arbitrary arc shape connecting the rear end face c of the lever and the upper end face d of the lever, which is not specially considered.

[Problems to be solved by the invention]

However, in the shape of the lever 1 shown in FIG. 7, with the rotation movement of the lever 1 from the standby state shown by the solid line to the printing state shown by the broken line, the upper end surface 4 of the support portion of the lever abuts in each state. The amount of deflection of the fulcrum holding spring 2 changes, and a stable fulcrum holding spring force P cannot be obtained. For this reason, the rotational movement of the lever 1 lacks stability, causing a significant decrease in printing quality and a significant decrease in durability performance due to rattling of the fulcrum 3. Further, as shown in FIG. 8, in such a lever / fulcrum pressing spring structure, the so-called platen gap is set by setting the distance between the tip of a printing wire (not shown) fixed to the tip of the lever and the printing medium surface. If it is made wider, the rotational movement of the lever 1 as the printing operation exceeds the normal movement range, and the armature 6 as the magnetic attraction unit collides with the core 9, and thereafter, about the fulcrum 3. From the pivoting movement, the end e of the armature 6 initially contacting the core 9
Transition to a pivoting motion about. As a result, the fulcrum 3 of the lever is separated from the upper end surface a of the frame 8 against the spring force P of the fulcrum pressing spring 2, so that the fulcrum 3 moves up and down once for one printing operation of the lever 1. That is,
When the printing operation is repeated with such a platen gap setting, the fulcrum 3 of the lever repeatedly collides with the upper end face a of the frame 8, causing significant wear, and further reducing the durability. As a countermeasure to this problem, it is possible to stabilize the pivoting movement of the lever and increase the fulcrum pressing spring force P. The fixed spring force for assembling and fastening the head must also be increased. As a result, there is a problem in that it is necessary to increase the rigidity of each component, resulting in an increase in the size and cost of the print head. An object of the present invention is to solve such a conventional problem and to provide an impact dot head in which printing quality and durability performance are remarkably improved at a low cost and without an increase in size.

[Means for Solving the Problems]

The impact dot head according to the present invention includes a lever formed at one end with a support portion rotatably pressed by a fulcrum support member by a pressing force of a spring member, and a shape of a contact portion of the lever with the spring member, It is characterized in that it is formed in an arc shape centered on the rotation center of the lever. In addition, the armature is provided at a position facing the core of the lever, and when the lever rotates, the shape of the lever at a portion that comes into contact with the spring member after the armature collides with the core is an arc around the center of rotation of the lever. Characterized in that it is formed in a shape protruding more toward the opposite side of the center of rotation of the lever.

【Example】

An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic side view of a lever peripheral portion of an impact dot head according to a first embodiment of the present invention. Since the basic structure of the impact dot head is the same as that of the above-mentioned prior art, the description will focus on the characteristic portions. The tip of the end protruding in the shape of a fishing hook is formed in an arc shape, and the fulcrum 3, the armature 6, and the end opposite to the fulcrum 3 are printed with the center of the arc as the rotation center f of the lever. Wire 7
In the lever 1 provided with a portion for fixing the fulcrum, the upper end surface 4 of the fulcrum portion with which the fulcrum pressing spring 2 abuts is formed by an arc g centered on the rotation center f of the lever. The fulcrum holding spring 2 is bent by the lever holder 13 and the upper end face 4 of the lever. As a result, the lever 1 is pressed at its upper end face 4 by the fulcrum holding spring 2 and the fulcrum part 3 is brought into contact with the upper end face a of the frame 8. The fulcrum support member 5 is formed by the side wall surface b of the fulcrum support member 5 and is abutted and held at a corner serving as a fulcrum support member. Force P applied to lever 1 by fulcrum holding spring 2
Always works toward the center of rotation f of the fulcrum portion 3 and functions to reliably hold the fulcrum. Further, as shown by the broken line in FIG. 2 which is a partially enlarged view of FIG. 1, even when the lever 1 which is a printing operation is rotated, the lever upper end surface 4 which is the contact portion of the fulcrum pressing spring 2 is not moved. , The amount of deflection of the fulcrum holding spring 2 is constant, and the lever 1 is always fixed at a constant load P.
Fulcrum 3 can be pressed against the fulcrum support. Accordingly, a stable rotational movement of the lever 1 can be obtained, and there is no backlash in the fulcrum portion, so that an impact head having high printing quality and excellent durability can be realized. FIG. 3 shows a second embodiment of the present invention. In the case of an impact dot head having a structure in which the end of the lever 1 is elastically pressed by the fulcrum pressing spring 2 and is used as a rotation fulcrum, when the printing operation is performed with the platen gap set wider than the normal setting. The rotational movement of the lever 1 for causing the printing wire to perform a printing operation exceeds the normal movement range, and the armature 6 serving as a magnetic attraction unit collides with the core 9, and thereafter,
First, a transition is made from the pivotal movement about the fulcrum 3 to the pivotal movement about the end e of the armature 6 in contact with the core 9. In this embodiment, as shown in FIG. 4, the shape of the upper end surface 4 of the lever fulcrum portion that comes into contact with the fulcrum holding spring 2 until the armature 6 collides with the core 9 is the same as in the first embodiment.
Although it is formed by an arc g centered on the rotation center f,
After the armature 6 collides with the core 9, the shape of the upper end surface 4 of the lever fulcrum portion with which the rear fulcrum pressing spring 2 abuts protrudes from the above-described arc g on the opposite side to the rotation center f, and as a result,
After the armature 6 collides with the core 9, the amount of deflection of the rear fulcrum holding spring 2 becomes larger by δ than in the first embodiment. Therefore, when the fulcrum 3 of the lever starts to float from the upper end surface a of the frame 8, the fulcrum 3 of the lever can be pressed with a fulcrum pressing spring force larger than usual. As a result, even when a printing operation is performed with the platen gap set wider than the normal setting, the fulcrum pressing spring force P after the armature 6 collides with the core 9 increases, so that the lever fulcrum 3 is prevented from rising from the upper end surface a of the frame 8 as much as possible, and the fulcrum portion 3 of the lever is prevented from repeatedly colliding with the upper end surface a of the frame 8, so that wear does not occur and durability performance is reduced. Nor. In this embodiment, after the armature 6 collides with the core 9, the shape of the upper end face h of the lever fulcrum to which the rear fulcrum pressing spring 2 abuts is linear, and the lever fulcrum 3 floats from the upper end a of the frame 8. The shape is such that the spring force P increases according to the amount. FIGS. 5 and 6 show third and fourth embodiments of the present invention. In the third embodiment shown in FIG. 5, the shape of the upper end surface 4 of the lever fulcrum portion that comes into contact with the fulcrum pressing spring 2 until the armature 6 collides with the core 9 is the same as the second embodiment, and the center of rotation f is the same. The upper end surface 4 of the lever fulcrum portion, which is formed by an arc g having the center and the rear fulcrum pressing spring 2 abuts after the armature 6 collides with the core 9, has a shape that is larger than the above-described arc g by the rotation center f. Arbitrary arc m protruding to the opposite side. Also, the sixth
In the fourth embodiment shown in the figure, the shape of the upper end surface 4 of the lever fulcrum portion which comes into contact with the fulcrum holding spring 2 until the armature 6 collides with the core 9 is the same as the second and third embodiments, and the center of rotation f The armature 6 is formed by an arc g having a center and the core 9
The shape of the protrusion of the upper end surface 4 of the lever fulcrum that the rear fulcrum pressing spring 2 abuts after collision with the armature 6 is the arc g around the armature end e that is the center of rotation after the armature 6 collides with the core 9. It is formed by an arc n protruding further to the opposite side to the rotation center f. In the case of the fourth embodiment shown in FIG. 6, when there is a structural restriction in increasing the fulcrum holding spring force P,
After the armature 6 collides with the core 9, the structure is such that unnecessary spring force is not increased. In any of the second, third and fourth embodiments, when the regular platen gap is set such that the core 9 does not collide with the armature 6, the regular platen gap where the core 9 and the armature 6 collide with the minimum stable fulcrum pressing spring force is set. When the gap is set to be wider than the gap, a strong fulcrum holding spring force P for suppressing the lever 1 from floating from the upper end surface a of the frame 8 can be obtained.

[Effect of the invention]

In the impact dot head of the present invention, as described above, since the lever shape of the portion that comes into contact with the fulcrum pressing spring member of the lever is formed in an arc shape about the center of rotation of the lever, the amount of deflection of the fulcrum pressing spring is constant. Thus, the lever can always be pressed with a constant load. Therefore, a stable rotational movement of the lever can be obtained, and there is no backlash at the fulcrum portion, so that an impact dot head having high printing quality and excellent durability can be realized. Also, when the lever rotates beyond the normal range, after the armature collides with the core, the shape of the part of the lever that comes into contact with the fulcrum holding spring is made smaller than the above-described arc centered on the center of rotation of the lever. Because the lever protrudes to the opposite side from the center of rotation of the lever, even if the platen gap is set wider than the normal setting, the fulcrum of the lever is difficult to separate from the fulcrum support member, and the fulcrum of the lever Of the impact dot head can be prevented without increasing the size of the impact dot head.
There is an effect that an impact dot head having excellent durability performance can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic side view of a lever peripheral portion of an impact dot head according to a first embodiment of the present invention. FIG. 2 is a partially enlarged view of FIG. FIG. 3 is an enlarged schematic side view of a portion around a lever of an impact dot head showing a second embodiment of the present invention. FIG. 4 is a partially enlarged schematic explanatory view of a lever of an impact dot head showing a second embodiment of the present invention. FIG. 5 is a partially enlarged schematic explanatory view of a lever of an impact dot head showing a third embodiment of the present invention. FIG. 6 is a partially enlarged schematic explanatory view of a lever of an impact dot head showing a fourth embodiment of the present invention. FIG. 7 is a partial schematic explanatory side view of the vicinity of a lever rotation fulcrum of an impact dot head according to the prior art. FIG. 8 is a partial schematic side view of the vicinity of a lever rotation fulcrum of an impact dot head according to the prior art. DESCRIPTION OF SYMBOLS 1 ... Lever 2 ... Support point presser spring 3 ... Lever fulcrum part 4 ... Lever fulcrum part upper end face 5 ... Support point part receiving member 6 ... Armature 7 ... Print wire 8 ... Frame 9 ... Core

Claims (2)

(57) [Scope of request for utility model registration] A lever having a support portion rotatably pressed against a fulcrum support member by a pressing force of a spring member, the lever having a lever formed at one end; An impact dot head formed in an arc shape centered on the center of rotation of the impact dot. 2. An armature is provided at a position facing the core of the lever, and when the lever pivots, the armature contacts the spring member after the armature collides with the core. 3. The impact dot head according to claim 1, wherein the lever is formed in a shape protruding from a circular arc centered on the center of rotation of the lever to a side opposite to the center of rotation of the lever.