JPH0771855B2 - Printing hammer drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Use of the Invention] In the present invention, a plurality of dot printing hammers arranged side by side at predetermined intervals along a printing line are reciprocally moved in the row direction, and printing is performed during this reciprocating movement. The present invention relates to a printing hammer driving device used for a dot line printer.

[Background of the Invention]

As shown in FIG. 3, the print hammer driving device includes a print hammer including a leaf spring 5 having a print pin 6 and a plunger 7 made of a magnetic material mounted on a print surface, a permanent magnet 1, a front yoke 2, a rear yoke 3, and It consists of the release electromagnetic coil 4 wound around the upper leg of the rear yoke 3, that is, the core 31,
The magnetic circuit structure holds the plunger 7, that is, the leaf spring 5, by suction. The lower end of the leaf spring 5 has a fixing screw 8 attached to the lower end of the front yoke 2. 9 is a front yoke 2 of the permanent magnet 1.
Is a spacer provided between and.

The leaf spring 5 is always attracted and held by the core 31 of the rear yoke 3 via the plunger 7 by the magnetic attraction force of the permanent magnet 1. When the electromagnetic coil 4 is excited, the magnetic attraction force is canceled out, and the leaf spring 5 flies due to the restoring force to cause the printing pin 6 to collide with a platen (not shown) via a sheet (not shown) and an ink ribbon. As a result, dots are printed on the paper.

There is a strong demand for improvement of the printing speed of the printing apparatus, and in order to realize it, it is indispensable to increase the characteristics of the printing hammer, that is, the number of dots per unit time. The structure is generally classified into a spring charge system, and one method of increasing the speed is to increase the natural frequency of the printing hammer including the printing pin 6, the plunger 7 and the plate spring 5. The natural frequency is determined by the spring constant of the leaf spring 5 and the mass of the movable part of the printing hammer, but it is quite difficult to reduce the weight of the movable part in terms of the structure, and the natural frequency is increased by increasing the spring constant. ing. Still another method is to increase the number of print hammers mounted. However, in this method, the gap between the electromagnetic coils 4 is narrowed and the winding width of the electromagnetic coil 4 is fixed in the configuration in which the core 31 and the printing hammer face each other. Had to be narrowed, the attraction area was reduced, and the magnetic attraction force against the spring force of the leaf spring 5 could not be obtained. Therefore, there is a limit to the increase of the spring constant of the leaf spring 5, and there is a limit to the improvement of the characteristics.

[Object of the Invention]

An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and increase the number of print hammers mounted to increase the print speed.

[Outline of Invention]

The present invention devises a print hammer and a magnetic circuit configuration so that the magnetic attraction force does not decrease even if the number of print hammers mounted is increased, and the print hammer is provided so that the print hammer and the magnetic circuit structure can be easily repaired when a change with time such as productivity or wear. The relationship with the yoke including the permanent magnet is devised. The present invention will be described below with reference to the drawings illustrating the embodiments.

Example of Invention

A comb core 13 is formed on the tip of a comb 12 provided above the permanent magnet 11 at an equal pitch, and a release electromagnetic coil 14 is wound around the comb core 13. A lower end of a yoke 15 provided below the permanent magnet 11 extends in parallel with the comb core 13. A plurality of hammer arms 16 are provided side by side on the front surface of the yoke 15 so as to be located between the comb cores 13 along the longitudinal direction thereof.
Is provided.

A back stop 18 extending parallel to the yoke 15 is further provided on the front surface of the hammer arm 16, and a plurality of suction portions 19 for sucking and holding the hammer arm 16 are provided at the upper end of the back stop 18.
Is provided. The wire 20 is joined to the upper end of the hammer arm 16 by means such as welding,
20 is slidably held by a wire guide 22 in a guide holder 21 provided behind the yoke 15. The hammer arm 16 has a large width so that a sufficient magnetic flux can pass through and a small magnetic resistance can be provided, and the hammer arm 16 is installed so as to be located between the comb cores 13 so that the magnetic flux can sufficiently flow from both side walls of the hammer arm 16. To be done. The shape of the movable portion of the hammer arm 16 is high in rigidity, and it is necessary for the entire hammer arm 16 to function as a spring. However, the thinned portion 17 is provided in this to secure a predetermined spring constant. I am trying.

The magnetic flux generated from the permanent magnet 11 passes through the yoke 15, the hammer arm 16, the back stop 18, and the attracting portion 19 to the comb core 13
Then, the hammer arm 16 bends its thinned portion 17 and is attracted and held by the attraction portion 19 by a magnetic attraction force. When the electromagnetic coils 14 on both sides of the hammer arm 16 are excited, the magnetic attraction force is offset, the hammer arm 16 is released and the wire 20 is caused to fly, and a dot is printed on the paper (not shown) at its tip.

In this embodiment, what is important is the bending energy of the hammer arm 16 as a spring in the thinned portion 17 of the hammer arm 16. The bending energy is 1 / the product of the square of the bending amount and the spring constant.
It is expressed as 2 and affects the printing power and the characteristics of the printing hammer during dot printing. In the configuration of FIG. 3, the amount of deflection of the leaf spring 5 is determined by the step and inclination between the fixed portion and the attraction portion of the leaf spring 5, so the permanent magnet 1, the yoke spacer 9, the rear yoke 3, etc. are processed with high precision. It was necessary to secure accuracy. On the other hand, in the case of this embodiment,
Since the bending amount of the hammer arm 16 is determined only by the back stop 18, it is sufficient to process only the back stop 18, and the accuracy can be easily secured.

When the hammer arm 16 returns to the suction portion 19 after printing, an impact force is applied and the hammer arm 16 and the suction portion 19 are worn.
When these wears have progressed, in the case of FIG. 3, it is necessary to replace the yoke 3 and the leaf spring 5, which are the main components of the printing hammer driving device, which makes the replacement work difficult and expensive. However, in the case of this embodiment, the backstop 18 and the hammer arm 16 are
There is an advantage that it is easy and inexpensive to replace, since it is only necessary to replace.

Furthermore, the back stop that does not have the electromagnetic coil 14 on the adsorption part
Since it is located at 18, the suction area can be sufficiently taken and the suction force can be secured even if the packing density of the printing hammers is increased.

The structure indicated by the chain double-dashed line in FIG. 3 indicates that the printing hammer driving device shown in FIG. 1 is arranged vertically and the wire 20 is concentrated at the printing position. The guide holder 21 has a symmetrical shape around the printing position and is fixed to an upper yoke (not shown). According to this configuration, the number of mounted printing hammers is doubled, and it becomes possible to provide a printing apparatus capable of printing at a higher speed than the configuration shown in FIG.

〔The invention's effect〕

As described above, according to the present invention, since the hammer arm is arranged between the cores and the suction portion is provided on the back stop,
Even if the number of mounted hammers is increased, the suction force does not decrease, high-speed characteristics can be maintained, and a printing hammer device capable of high-speed printing can be realized. Moreover, since the structure is determined only by the flexible back stop, it is possible to secure the effect easily and with high accuracy, and it is possible to obtain effects such as easy replacement of worn parts.

[Brief description of drawings]

1 and 2 are sectional views showing an embodiment of the device of the present invention,
FIG. 3 is a sectional view showing an example of a conventional device. In the figure, 11 is a permanent magnet, 12 is a comb, 13 is a comcore,
14 is a release electromagnetic coil, 15 is a yoke, 16 is a hammer arm, 17 is a thinning part, 18 is a backstop, 19 is an adsorption part, 20
Is a wire, 21 is a guide holder, and 22 is a wire guide.

Claims (3)

[Claims] 1. A dot line printer for reciprocating a plurality of dot printing hammers arranged side by side at a predetermined interval along a print line along the print line and printing in the process of the reciprocating movement. A hammer arm fixed to the upper part is arranged between cores around which an electromagnetic coil is wound, a back stop is provided behind the hammer arm, and the magnetic attraction force of a permanent magnet attracts and holds the hammer arm to the back stop. The printing hammer drive device is characterized in that the hammer arm is released by energizing the printer to print dots. 2. A guide holder, which holds a guide for slidably holding the printing element, is fixed to the yoke that serves as a path for the magnetic flux of the permanent magnet, as well as fixing the hammer arm. The printing hammer driving device according to the first section. 3. The printing hammer driving device according to claim 2, wherein the guide holder connects the vertically facing hammerbanks.