JPH06246938A - Printing head - Google Patents

Abstract

PURPOSE:To control rotation of a returning coil spring by a method wherein a detent part is provided on the returning coil spring, another detent part is provided on a spring holder or its adjacent member, and those both detent parts are engaged with each other. CONSTITUTION:A printing head is so constructed that a clapper is returned to a non-operating position with a returning coil spring 101 stored in a spring holder 103, and printing is carried out by moving the clapper to an operating position against spring force of the returning coil spring 101 with attracting force which is generated by turning on an electromagnet. Further, detent parts 101a, b are protruded on the returning coil spring 103 side. Besides, an engaging groove 103b is formed on the spring holder 103 side, and the detent parts 101a, b of the returning coil spring 103 is so fitted as to be engaged with the engaging groove 103b of the spring holder 103. The returning coil spring 101, a spring fitting hole 103a of the spring holder 103, and its base 103c do not slide-contact with each other, and abrasion with the base 103c can be eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to, for example, a print head of an impact wire dot type printing apparatus, and more particularly to a return coil spring for returning a clapper and a spring holder for holding the return coil spring. The present invention relates to a return coil spring and a spring holder, in particular, a device devised to prevent wear of the spring holder and to provide stable operation over a long period of time by restricting relative rotation.

[0002]

2. Description of the Related Art A print head has, for example, FIGS.
It has a structure as shown in FIG. FIG. 15 is a view showing a half of the print head in a cross section. First, there is the nose case 1. A yoke 3 is installed in the nose case 1, and an electromagnet 5 is installed in the yoke 3. The electromagnet 5 is composed of a core 5a and a coil 5b arranged around the core 5a. Further, a clapper 7 is arranged on the end face side of the electromagnet 5, and the clapper 7
A wire 8 is fixed to the front end portion 7a of the print head on the center side. A spring holder 9 is attached to the yoke 3, and a return coil spring 11 is attached to the spring holder 9. Incidentally, reference numeral 13 in the drawing
Is a stopper, and reference numeral 15 is a coil spring.

In the above structure, when the electromagnet 5 is off, the clapper 7 is returned to the right side in the drawing by the returning coil spring 11 and is in contact with the stopper 13, as shown in FIG. On the other hand, when the electromagnet 5 is turned on, the attraction force causes the clapper 7 to move to the left side in the figure against the spring force of the restoring coil spring 11. By the operation of the clapper 7, predetermined printing is performed on a sheet (not shown) via the wire 8.

[0004]

The above-mentioned conventional structure has the following problems. That is, as described above, the clapper 7 repeats the turning operation by turning the electromagnet 5 on and off, and the returning coil spring 1 is caused by the turning operation and minute vibrations generated during printing.
The phenomenon that 1 rotates in the spring holder 9 occurs.
When such a rotation phenomenon of the return coil spring 11 occurs, the edge 11a of the return coil spring 11 and the bottom surface 9a of the spring holder 9 are repeatedly brought into sliding contact with each other, and as a result, the bottom surface of the resin spring holder 9 is in contact. 9
There was a problem that a was removed. The wear of the bottom surface 9a of the spring holder 9 gradually progresses as the number of printings increases, and as a result, the spring load of the return coil spring 11 decreases. In this way, when the spring load of the return coil spring 11 decreases, the impact force during printing abnormally increases,
This causes a decrease in responsiveness due to the longer recovery time of the clapper 7, and causes a ribbon hooking phenomenon. Also, this kind of problem does not become a problem when the printing speed is relatively slow, but recently,
The printing speed is being increased, and this is a problem that has become apparent as the printing speed is increased. To solve these problems, for example, the one disclosed in Japanese Patent Laid-Open No. 4-261867 has been proposed. This is to prevent a direct sliding contact between the coil spring for return and the bottom surface of the spring holder by interposing a spacer on the bottom surface in the spring holter, thereby suppressing wear of the bottom surface of the spring holder. Is. However, in such a structure, first, the number of parts is increased (spacers are required for the number of springs), and it is complicated to mount the plurality of spacers in the respective spring holders. This is not a preferable method because it causes other problems such as work being required.

The present invention has been made on the basis of such a point, and an object of the present invention is to slide the coil spring for return and the bottom surface of the spring holder without increasing the number of parts or complicated assembling work. An object of the present invention is to provide a print head that prevents wear of the bottom surface of the spring holder due to contact and exerts a stable function for a long period of time, thereby reliably responding to high printing speed.

[0006]

In order to achieve the above object, the print head according to the present invention is configured such that the clapper is returned to the non-operating position by the return coil spring housed in the spring holder and the electromagnet is turned on. In the print head configured to perform printing by moving the clapper to the operating position against the spring force of the return coil spring by the generated suction force, the return coil spring is provided with a locking portion, The present invention is characterized in that the spring holder or a member in the vicinity thereof is provided with a locking portion, and the rotation of the return coil spring is restricted by engaging these both locking portions. At this time, at least one of both ends of the return coil spring is projected and formed as a locking portion, and a groove or hole that engages with the locking portion is formed on the spring holder side to engage this. It can be considered as a stop. Further, it is conceivable that at least one of both ends of the return coil spring is projected and formed as a locking portion, and the clapper guide groove formed on the open end side of the spring holder is used as a locking portion. . further,
It is conceivable that the return coil spring has a non-circular shape so that the engagement of the return coil spring with the spring holder shape restricts the rotation of the return coil spring.

[0007]

That is, in the case of the present invention, the return coil spring is provided with the engaging portion, and the spring holder or a member in the vicinity thereof is provided with the engaging portion so that both engaging portions are engaged with each other. The rotation of the return coil spring is restricted. Various configurations are conceivable for the both locking portions. For example, at least one of both ends of the return coil spring is projected and formed as a locking portion, and the locking portion that engages with the spring holder or It is conceivable to form a groove or a hole in the neighboring member. In addition, the shape of the return coil spring itself becomes a non-circular shape, for example, a triangle or a quadrangle in consideration of the shape of the spring holder hole, so that the rotation of the return coil spring is restricted by the action of the engaging portions of both. In addition, each corner portion is a locking portion, and a portion of the spring holder corresponding thereto functions as a locking portion.
However, the contents are not limited to the above.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The first embodiment of the present invention will be described below with reference to FIGS.
An example will be described. First, in the case of the present embodiment, the return coil spring 101 is constructed as shown in FIGS. That is, both ends 101a and 101b serve as locking portions and are projected by a predetermined amount.
The locking portion 101a and the locking portion 101b are projected and formed at the same position in the circumferential direction, and as shown in FIG. 2, the locking portion 101b overlaps when viewed from the locking portion 101a side. It becomes a state.

On the other hand, the spring holder 103 is constructed as shown in FIGS. That is, the spring holder 103 is formed with a spring mounting hole 103a, and at one position in the circumferential direction thereof, a locking groove 103b extended in the axial direction.
The bottom of the spring mounting hole 103a is the bottom surface 103.
It is c.

According to the above structure, when the return coil spring 101 is mounted in the spring mounting hole 103a of the spring holder 103, as shown in FIGS. 5 and 6, the locking portion 101 of the return coil spring 101 is provided.
The a and 101b are mounted in such a state that they are engaged with the locking groove 103b. That is, the locking portions 101a and 101b of the return coil spring 101 are engaged with the locking grooves 103b of the spring holder 103, whereby the rotation of the return coil spring 101 can be restricted.

According to this embodiment, the following effects can be obtained. That is, the rotation of the return coil spring 101 can be restricted. This is because the return coil spring 101 has locking portions 101a and 101b.
On the other hand, the locking groove 1 is provided on the spring holder 101 side.
This is because rotation of the return coil spring 101 is regulated by forming 03b and engaging them. Therefore, the return coil spring 10
1 and the spring mounting hole 103 of the spring holder 103
The sliding contact with the bottom surface 103c of a is also eliminated, and the wear of the bottom surface 103c can be eliminated. Therefore, the bottom surface 103c
Due to wear of the spring holder, that is, a decrease in spring load of the return coil spring 101 against the clapper due to wear of the bottom surface of the spring holder, an abnormal increase in impact force at the time of printing due to this, and a longer recovery time of the clapper. It has become possible to provide a stable function over a long period of time by preventing the occurrence of a decrease in responsiveness, the occurrence of a ribbon hooking phenomenon, etc. Further, at that time, there is no increase in the number of parts or a complicated assembling work as in the conventional case, and there is no problem even if a relatively inexpensive resin spring holder 103 is used as in the conventional case. There is nothing.

Next, a second embodiment will be described with reference to FIG. In this embodiment, the projecting directions of the locking portions 101a and 101b of the return coil spring 101 are changed. That is, in the case of the first embodiment, the locking portion 101
Although a and 101b are projected outward in the radial direction,
In the case of this embodiment, it is projected in the tangential direction. However, in this case, the position of the locking groove 103b of the spring holder 103 is also changed accordingly. Therefore, also in the case of this embodiment, the same effect as in the case of the first embodiment can be obtained. Also, the locking portion 10
The projecting directions of 1a and 101b may be directions other than those of the first and second embodiments, and the projecting amount and the like may be arbitrarily set. Also, the locking portions 101a, 10
The protruding positions of 1b do not necessarily have to be the same position, and they may be made to protrude at different positions. However, correspondingly, two locking grooves 103b of the spring holder 103 are also formed at different positions.

A third embodiment will be described with reference to FIGS. In the case of this embodiment, as shown in FIGS. 8 and 9, the return coil spring 101 is provided with the locking portion 101b only on one side. The locking portion 101b is located on the bottom surface 103c side of the spring holder 103, and is projected / formed in the axial direction. on the other hand,
On the spring holder 103 side, as shown in FIGS. 10 and 11, a locking hole 103d is formed at a predetermined position on the bottom surface 103c. Then, as shown in FIG. 12, the return coil spring 101 is mounted in the spring mounting hole 103a of the spring holder 103 in such a positional relationship that the locking portion 101b is engaged in the locking hole 103d. Become. That is, the rotation of the return coil spring 101 is regulated by the engagement relationship between the locking portion 101b and the locking hole 103d. Therefore, also in the case of this embodiment, the same effect as in the case of each of the above embodiments can be obtained.

Next, a fourth embodiment will be described with reference to FIGS. 13 and 14. In the case of this embodiment, first, the locking portion 101a is projected and formed on one end side of the coil spring 101 (the side opposite to the bottom surface 103b of the spring holder 103). The locking portion 101a is formed so as to project outward in the radial direction. On the other hand, a locking groove 103e is formed on the spring holder 103 side. Incidentally, in the case of this embodiment, it is utilized that the upper part of the spring holder 103 on the open end side is provided with guide grooves for guiding the clapper 105 (shown by a broken line in FIG. 14) on both sides. Then, a part of the guide groove is used as the locking groove 103e. Then, as shown in FIG. 14, the return coil spring 101 is attached to the spring holder 103 in a state where the locking portion 101a is engaged with the locking groove 103e. Therefore, the rotation of the return coil spring 101 is restricted by the engagement relationship between the locking portion 101e and the locking groove 103e, and a desired effect can be obtained.

The present invention is not limited to the above embodiments. First, the shape of the return coil spring 101 is not a cylindrical shape but a polygonal pillar shape, for example, a triangular pillar shape or a quadrangular pillar shape, and the shape of the insertion hole on the spring holder side is also adapted to the shape. It is conceivable that the rotation of the return cosling can be restricted by this. In addition, various configurations such as the above combinations are conceivable as the configuration of the return coil spring and the locking portion formed on the spring holder or a member in the vicinity thereof. Further, as the basic structure of the print head, the one in which the clapper and the wire are integrated has been described as an example (shown in FIG. 15). It is needless to say that the same can be applied to a structure in which a wart-shaped member (in place of the wire) is attached.

[0016]

As described above in detail, according to the print head of the present invention, the return coil spring is provided with an engaging portion, and the spring holder or a member in the vicinity thereof is provided with an engaging portion. Since the rotation of the return coil spring is restricted by engaging with, it is possible to prevent the bottom portion on the spring holder side from being worn due to the rotation of the return coil spring. Therefore, it has become possible to stably maintain the functions such as stable maintenance of the impact force of printing for a long period of time.

[Brief description of drawings]

FIG. 1 is a side view of a return coil spring according to a first embodiment of the present invention.

FIG. 2 is a view showing a first embodiment of the present invention and is a top view of a return coil spring.

FIG. 3 is a top view of the spring holder according to the first embodiment of the present invention.

FIG. 4 is a cross-sectional view of a spring holder according to the first embodiment of the present invention.

FIG. 5 is a view showing the first embodiment of the present invention and is a top view showing a state in which a return coil spring is attached to the spring holder.

FIG. 6 is a cross-sectional view showing a first embodiment of the present invention in which a return coil spring is attached to a spring holder.

FIG. 7 is a view showing a second embodiment of the present invention and is a top view of a return coil spring.

FIG. 8 is a side view of a returning coil spring in a view showing a third embodiment of the present invention.

FIG. 9 is a view showing a third embodiment of the present invention and is a top view of a return coil spring.

FIG. 10 is a top view of the spring holder according to the third embodiment of the present invention.

FIG. 11 is a cross-sectional view of a spring holder according to a third embodiment of the present invention.

FIG. 12 is a sectional view showing a third embodiment of the present invention in which a return coil spring is attached to a spring holder.

FIG. 13 is a top view showing a fourth embodiment of the present invention in which a return coil spring is mounted on a spring holder.

FIG. 14 is a view showing a fourth embodiment of the present invention and is a top view showing a state in which a return coil spring is attached to a spring holder.

FIG. 15 is a cross-sectional view showing a configuration of a half of a print head in a conventional example.

FIG. 16 is a side view showing a configuration of a returning coil spring in a conventional example.

FIG. 17 is a view showing a conventional example and is a top view of a coil spring for return.

[Explanation of symbols]

 5 Electromagnet 7 Clapper 8 Wire 101 Coil Spring for Returning 101a Locking Part 101b Locking Part 103 Spring Holder 103b Locking Groove (Locking Part)

Claims (4)

[Claims] 1. The clapper is returned to a non-operating position by a returning coil spring housed in a spring holder, and the clapper resists the spring force of the returning coil spring by an attraction force generated by turning on an electromagnet. In the print head configured to move to the operating position to perform printing, the return coil spring is provided with a locking portion, and the spring holder or a member in the vicinity thereof is provided with a locking portion. A print head characterized in that rotation of a return coil spring is restricted by engaging a locking portion. 2. The print head according to claim 1, wherein at least one of both ends of the return coil spring is projected and formed as a locking portion, and the spring holder side is engaged with the locking portion. A print head, characterized in that a groove or hole is formed and used as a locking portion. 3. The print head according to claim 1, wherein at least one of both ends of the return coil spring is projected and formed as a locking portion, and a clapper formed on the open end side of the spring holder. A print head having a guide groove as a locking portion. 4. The print head according to claim 1, wherein the return coil spring has a non-circular shape to restrict rotation of the return coil spring.