JPS61266259A - Dot printer head - Google Patents

Abstract

PURPOSE:To enable a needle to be drive at a high speed, by making return body by a plurality of springs each of which starts acting at different timing before an armature is attracted by a magnetic coil. CONSTITUTION:A stopper 5 is installed backward in a head case 1, and armatures 7 are provided rotatable in the area between the stopper 5 and cores 6 of magnetic coils 2. Each of the armatures 7 is positioned by a method wherein one end thereof is pressed on the end of the magnetic coil 2 by a leaf spring 8 and guided to a ring-shaped armature guide 9. In this construction, if selectively energized, the magnetic coil 2 generates magnetic force to attract the armature 7 to the core 6. At this time, the armature 7 rotates in a free end 15 thereof on its fulcrum of the end portion thereof pressed by the leaf spring 8 and simultaneously drives needle 4 in advance. Thus, the needle 4 can perform printing in a desired method by the tip end thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a dot printer head for a dot printer that performs printing by selectively driving a plurality of needles to make them move back and forth.

2. Description of the Related Art Conventionally, there have been dot printers that perform printing by selectively driving a plurality of needles to make them reciprocate. These types of printers can be roughly divided into impact type and ink dot type, but in either type, the dot printer head is equipped with a mechanism to drive the needle to make it reciprocate. . An example of such a mechanism is to use a magnetic coil to magnetically attract and rotate an armature that is rotatable within a certain range from its initial position, and then use the armature to drive the rear end of the needle to perform printing. There is also a device in which the armature is returned to the initial position together with the needle by a return member after printing. In such devices, a spring is generally used as the return member.

Problem to be Solved by the Invention The attractive force of the magnetic coil to the armature is inversely proportional to the square of the distance between them. On the other hand, the return force of the armature to its initial position by the return member is inversely proportional to the distance between the armature and the magnetic coil, with a numerical correspondence of -order.

For this reason, as the distance becomes narrower, the attractive force of the magnetic coil increases rapidly, whereas the return force applied to the armature increases only linearly. Therefore, the return force of the armature does not impose a large load on driving the armature when the distance is narrow, but it becomes a large load when the distance is wide. Here, the driving speed of the needle by the armature becomes slow in the initial stage of driving, and there is a drawback that the needle cannot be driven at high speed.

The present invention has been made in view of these points, and an object of the present invention is to obtain a dot printer head that can drive needles at high speed.

Means for Solving the Problems The present invention provides a plurality of armatures that drive a plurality of needles by being magnetically attracted to a magnetic coil and rotating from an initial position. A return body for returning the needle to the initial position together with the needle was provided, and these return bodies were formed by a plurality of springs each having a different start time during the time until the armature was attracted to the magnetic coil.

Thus, the armature rotates by being magnetically attracted to the magnetic coil and drives the needle. Thereafter, the needle is returned to the initial position by the return member.

At this time, the return body continues to apply force to return the armature to its initial position. This return force is weak at the beginning of the armature rotation due to the spring that starts acting halfway during the armature rotation, and then increases rapidly. On the other hand, the attraction force of the magnetic coil to the armature is also weak at first, but increases rapidly later. Therefore, at the beginning of rotation when the suction force is weak, the return force is also weak, so this does not become a large load. Here, the driving speed of the needle by the armature does not slow down even in the initial stage of driving the needle, making it possible to drive the needle at high speed.

Embodiment of the Invention An embodiment of the present invention will be described with reference to FIGS. 1 to 5. FIG. A head case 1 in the form of a housing is provided, and within this head case 1 there is a drive unit 3 whose drive source is a plurality of magnetic coils 2 arranged in a circumferential manner, and a reciprocating movement driven by this drive unit 3. A plurality of moving needles 4 are housed therein.

That is, a stopper 5 is attached to the rear inside of the herad case 1, and an armature 7 that is rotatable between the stopper 5 and the core 6 of the magnetic coil 2 is provided. These armatures 7 have one end pressed against the end of the magnetic coil 2 by a leaf spring 8, and the pressed end is guided and positioned by a ring-shaped armature guide 9. A return body 10 for pressing the armature 7 against the stopper 5 is provided in parallel with the magnetic coil 2. These return bodies 10 are comprised of an intermediate action spring 12 of a coil spring held within a housing-like casing 11 and an initial action spring 13 of a coil spring disposed within this intermediate action spring 12. The intermediate action spring 12 is set to have a size that starts acting during the rotation of the armature 7. On the other hand, the initial action spring 13 is set to have a size that can press the armature 7 against the stopper 5 from the beginning, and is covered by a flexible tube 14.

On the other hand, the needle 4 has its rear end fixed to a free end 15 of the rotating end of the armature 7. The tips of those needles 4 are connected to the herad case 1.
They are held by being inserted into a plurality of needle holes 16 provided in a vertical line at the tip. Here, the direction in which the needles 4 are arranged is such that their axial direction and the direction of rotation of the free end 15 substantially match.

In such a configuration, when the magnetic coil 2 is selectively energized, the magnetic coil 2 emits magnetic force and attracts the armature 7 to the core 6. At this time, the free end 15 of the armature 7 rotates using the end pressed by the leaf spring 8 as a fulcrum, and at the same time, the needle 6-4 is driven and moved forward. Here, the needle 4 is used to print in a desired manner at its tip, and after printing, the magnetic coil 2 is de-energized. Then, the armature 7 is returned to the initial position together with the needle 4 by the return member 10. The desired position is a position where the free end 15 is pressed against the stopper 5.

Here, in the return body 10, the armature 7 is connected to the magnetic coil 2.
Even in the process of being attracted by the armature 7, a force is given to the armature 7 to return it to its initial position. This return force is weak at the beginning of the chimachi's one-fufu rotation, but increases rapidly later. That is, at the beginning of the rotation of the chimney 1, only the initial action spring 13 is compressed and acts, so the return force is weak, and from the middle of the rotation, the intermediate action spring 12 is compressed and begins to act, and its return force increases rapidly. do. The relationship between the return force of the armature 7 and the compression amount of the return body 10 is shown graphically in FIG.

Note that the flexible tube 14 is connected to the intermediate action spring 12.
This prevents interference between the spring 13 and the initial action spring 13, and does not deform when the armature 7 rotates and prevent the movement of the armature 7.

Therefore, the attractive force of the magnetic coil 2 with respect to the armature 7 is inversely proportional to the square of the distance between the core 6 of the magnetic coil 2 and the armature 7. Therefore, the attraction force is
The narrower the interval, the sharper the increase. For this reason, a restoring force by the restoring body 10 is acting on the armature 7, and the speed at the beginning of rotation is slower than at the end of the rotation. However, at the beginning of rotation when a strong suction force cannot be obtained, only the initial action spring 13 acts on the armature 7, and its return force is weak. Therefore, the return force of the armature 7 does not impose a large load on the suction force at the beginning of the rotation of the chimney 1, and the needle 4 driving speed by the armature 7 becomes high in the initial stage, making it possible to drive the needle 4 at high speed. become.

Next, as a modification, the intermediate acting spring may be compressed and held in advance, and when it acts, it may be further compressed from that state. In this way, the strength of the return force at the early and late stages of rotation of the armature is further emphasized in comparison with those having the same spring rate. The relationship between the restoring force of the armature and the amount of compression of the restoring body is shown graphically in FIG.

In addition, in practice, a plurality of springs may be used as the initial action spring 13, the intermediate action spring 12, or both.

Effects of the Invention In the present invention, the return body that returns the armature attracted to the magnetic coil to the initial position together with the needle is formed by a plurality of springs each having a different start time during the time until the armature is attracted to the magnetic coil. Therefore, the driving speed at the initial stage of driving the needle becomes high, and therefore the needle can be driven at high speed, and even if the suction force at the beginning of armature suction is weakened, the needle can be driven sufficiently. It has the following effects: a small magnetic coil can be used, and the entire device can therefore be made smaller and lighter.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional side view of a drive section showing an embodiment of the present invention;
Fig. 2 is a longitudinal side view of the whole, Fig. 3 is a longitudinal side view of the return body, Fig. 4 is a graph showing the relationship between the return force of the armature and the compression amount of the return body, and Fig. 5 is the armature in a modified example. 3 is a graph showing the relationship between the restoring force and the amount of compression of the restoring body. 2... Magnetic coil, 4... Needle, 7... Armature, 10... Returning body, 12... Intermediate action spring (spring), 13... Initial action spring (spring) Applicant Tokyo Electric Co., Ltd. j+-j'yl busy εG-R

Claims (1)

[Claims] A plurality of armatures are provided that drive a plurality of needles by being magnetically attracted to a magnetic coil and rotated from an initial position, and the armatures attracted to the magnetic coil are returned to the initial position together with the needles. A dot printer head, characterized in that a return body is provided, and these return bodies are formed by a plurality of springs each starting at a different time during the time until the armature is attracted to the magnetic coil.