JPS609765A - Printing head - Google Patents

Abstract

PURPOSE:To permit the driving of a wire with a great suction force at high speeds by a method in which a plunger is set such that the side end of the plunger in the through hole of a yoke is made close to the other end of the plunger. CONSTITUTION:A plunger 21 is projected to both upside and downside from the upper through hole 19 and set, however, such that the opening edge 20e of the through hole 20 of other yoke 18 is close to the lower edge 21e of the plunger. When an exciting coil 15 is electrically energized, the plunger 21 is sucked into the through hole 20 against a return spring 23 so that the magnetic resistance between the plunger 21 and the yoke 18 is minimized, and printing is made. Since magnetic flux begins to flow in the plunger 21 under the condition that the lower end of the plunger 21 is close to the edge 20e of the through hole of the yoke 18 at the time when the suction of the plunger starts, greater amount of magnetic flux passes in the early period of suction and a great suction force is therefore generated.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] In a so-called serial dot printer in which the print head moves relative to the platen in the space direction,
Printing is performed by impacting the ink ribbon on the printing paper with the tip of a wire driven by an electromagnet. The present invention thus relates to a print head in which the wire is driven by an electromagnet.

[Technology background]

FIG. 1 is a plan view showing an outline of the serial printer, and FIG. 2 is a front perspective view of the print head. A continuous printing paper 2 is wound around the platen 1 as a printing medium, and a feed screw 3 and a guide shaft 4 are arranged parallel to the platen 1.
A carrier 6 on which a print head 5 is mounted is supported. By rotationally driving the feed screw 3 by a motor M via a belt 7, the print head 5 is transported at a constant speed in the space direction indicated by an arrow a+.

At the tip of the print head 5, a plurality of wires W), W2...
・Wires W9 are arranged at equal intervals in a direction perpendicular to the space direction, and at each time t1, t2... wires W1, W2... are selectively driven by an electromagnet built into the head at a constant cycle. By causing the dots to protrude, a character such as "A", for example, is formed on the paper 2 by a combination of dots D, . . . . Furthermore, if the printing paper 2 is pressure-sensitive paper,
When the wire WI-w2... is driven and the tip of the wire hits the paper 2, a dot D... is recorded by the impact, but in the case of plain paper, the ink ribbon 8 is moved as shown in Figure 1. Impact is added through

[Prior art and its problems]

FIG. 3 is a sectional view showing the internal structure of the print head 5, illustrating a release type print head. 9 is an iron core around which an excitation coil 10 is wound. A magnetic block 13 is connected to the yoke portion 11 connected to the iron core 9 via a permanent magnet 12.
The flapper type armatures 14 are mounted one on top of the other in this order. A wire W is attached to the tip of the armature 14, and the magnetic flux from the permanent magnet 12 normally causes the armature 1 to
4 is attracted to the iron core 10. However, when the excitation coil 10 is energized to generate a magnetic flux in a direction that cancels the magnetic flux produced by the permanent magnet 12, the armature 14 is released from the iron core 9. Since armature 14... is made of plate springs, 311 when released from iron core 9.
With one force, the wire W moves in the direction of the arrow a2, advances from the tip of the print head shown in FIG. 2, and impacts the print 8I, 2.

FIG. 4 is a plan view of the leaf spring that constitutes the armature 14 in this way. The armadures 14 are arranged radially, and their respective outer ends are connected by a ring-shaped portion to form an integral structure. and each armature 14
Wires w1, w2, etc. are attached to the inner ends of...

The tips of the wires w1, w2, etc. attached to the inner ends of the leaf springs 14, which are arranged radially as shown in FIG. Wire W! in two rows or in a staggered pattern.・Wz... is being gradually transformed. If the amount of deformation is large, the wear during sliding on the wire guide section will also be large, so the inner ends of the leaf springs 14 should be extended as far as possible toward the center C of the print head, and the inner ends of the leaf springs 14 should be extended as far as possible to the center C side of the print head. Wire WI-w2・
It is desirable to install .... Furthermore, in the case of a print head for printing Kanji characters, more wires W1, Wz, . . . are required, and in reality, 24 wires are used. To print such complex characters, more wires, an electromagnet for driving the wires, and a leaf spring for the armature are required.
4... is required.

In this way, in order to increase the number of armatures 14... and prevent rapid deformation of the wires W1, Wz..., the intervals in the circumferential direction of the wires W1, Wz... should be made as small as possible. In addition, it is necessary to place the wires W+ -Wz... as close to the center C position of the print head as possible.

As shown in Figures 3 and 4, an electromagnet in which the armature operates as a clapper can meet the above requirements because only the tip of the armature can be extended to the center of the print head. Since the wire is attached to the plunger provided in the center of the coil, it is extremely difficult to meet the above two requirements. When a flapper type armature is attracted to the iron core, the wire cannot advance any further, and if the gap between the armature and the iron core is large, the magnetic resistance is large and the armature cannot be attracted. Therefore, it is difficult for the clapper type armature to have a sufficient stroke, but in the case of a plunger set, the stroke of the plunger can be sufficiently large. On the other hand, since the mass of the plunger is large, it is difficult to increase the speed.

[Purpose of the invention]

The purpose of the present invention is to eliminate such problems in conventional print heads, to realize a print head that has substantially the same characteristics as a plunger set electromagnet, and in which the wire can be disposed at the center of the print head. be.

[Structure of the invention]

The technical means of the present invention taken to achieve this purpose is to arrange a large number of iron cores around which excitation coils are wound around the center of the print head, and to align the center of each excitation coil approximately parallel to the center of the print head. Extending the yoke 6- from both ends of each core to the center of the print head, making vertical through holes at the tips of both yokes, inserting and arranging the plunger into the re-through hole, and The plunger always protrudes from the through hole in one yoke on both sides, and the plunger is arranged so that the plunger side end of the through hole in the other yoke and the other end of the plunger are in close position. , are each required as essential requirements.

(Embodiments of the Invention) Next, how the print head according to the present invention is actually embodied will be explained with examples. Fig. 5 is a central sectional view showing an embodiment of the print head according to the present invention. A yoke 17 is provided at both upper and lower ends of the iron core 16 around which the excitation coil 15 is wound.
．． 18 are connected. The tips of both yokes 17 and 18 extend toward the print head center C side. In this way, a large number of excitation coils 15... are arranged around the print head center C, and the yoke tips are concentrated on the print head center C side, similar to the armature 14... in Fig. 4. ing. Through holes 19, 20 are formed at the tips of the yokes 17, 18 in parallel with the iron core 16, and a plunger 21 made of a magnetic material is inserted into one of the through holes 19.

A return spring 23 is disposed between the spring receiver 22a at the lower end of the non-magnetic frame 22 and the plunger 21, and the return spring 23 always urges the plunger 21 toward the stopper part 22b of the two wheels of the frame. are doing. In this state, the plunger 21 protrudes upward and downward from the upper through hole 19, but with respect to the through hole 2.0 of the other yoke 18, the opening edge 20e of the through hole and the lower end edge 21e of the plunger are arranged so that they are close to each other.

When the excitation coil 15 is now energized, the magnetic flux induced by the excitation coil 15 passes through the iron core 16 - yoke 17 - plunger 21 - yoke 18 - iron core 16 route. Then, the plunger 21 is attracted into the through hole 2o against the return spring 23 so that the magnetic resistance between the plunger 21 and the yoke 18 is minimized. At this time, the wire W is urged in the direction of the arrow a2, and printing is performed as described above.

When the excitation coil I5 becomes de-energized, the plunger 2
1 is pushed up by the return spring 23 and the stopper part 21
It comes into contact with and stops.

Non-magnetic rings 24.
25 is provided, and the plunger 21 is always inserted into the through hole 19.
It guides you to move through 20.

In this configuration, yoke 17 - iron core 16 - yoke 18
If a permanent magnet is interposed in the middle of the route, the plunger 21 is always attracted into the through hole 2o by its magnetic force, and the excitation coil 15 is energized in a direction to cancel the magnetic flux of the permanent magnet, the return spring 23 is The force releases the plunger 21 in the upward direction.

Therefore, by attaching the wire to the upper end of the plunger 21, a release type print head is obtained.

The frame 22 has a ring shape, and the yoke 17.1
8 are inserted at equal intervals in the circumferential direction. As shown in FIG. 6, a non-magnetic, extremely thin-walled cylinder 26 may be inserted across the through-hole 19.20 of the yoke 17.18, and the plunger 9-21 may be moved up and down within it. .

〔Effect of the invention〕

As described above, according to the present invention, magnetic flux begins to flow through the plunger 21 when the lower end of the plunger 21 approaches the through-hole edge 20e of the yoke 18 at the start of the plunger suction. A large amount of magnetic flux passes through it, generating a large attractive force. That is, compared to conventional flapper armatures in which magnetic flux is generated from the position furthest from the iron core, the attracting force is greater and the wire can be driven faster and more powerfully. Therefore, the problem of operating speed, which is a disadvantage of the conventional plunger set printhead, is also eliminated.

Furthermore, in the flapper type armature, when the armature comes into contact with the iron core, the wire cannot advance any further, and when the wire is worn out and shortened, the wire cannot reach the platen 1. However, since the plunger 21 of the present invention does not come into contact with a rigid body such as an iron core, but is attracted against the return spring 23, the inertia of the plunger 21 also acts, and the wire tip is brought into contact with the platen 10-1. The stroke can be extremely long.

Although it functions similarly to a print head with a plunger set, the large-volume excitation coil and iron core are sufficiently spaced outward from the center C of the print head, and only a portion of the plunger is disposed at the center of the print head. , 3 and 4, it is possible to reduce the size of the print head. Therefore, it is easy to increase the number of wires and move each wire closer to the center of the print head, thereby increasing the number of dots. Since the excitation coil is located on the outside,
Heat dissipation is also easy.

[Brief explanation of the drawing]

Figure 1 is a plan view showing the outline of a serial dot printer.
Fig. 2 is a perspective view of a wire-type print head, Fig. 3 is a central cross-sectional view of the print head, Fig. 4 is a plan view showing the armature of the print head, and Fig. 5 and subsequent figures show a print head according to the present invention. FIG. 5 is a central sectional view of the print head, and FIG. 6 is a sectional view showing another embodiment of the plunger guide portion. 15 is an excitation coil, 16 is an iron core, 17.18 is a yoke,
19. 20 is a through hole, 20e is an edge portion of the through hole, 21
21e is a plunger, 21e is an edge portion at the lower end of the plunger, 22 is a frame, 23 is a return spring, and W is a wire. Patent Applicant: Fujitsu Limited Agent, Patent Attorney: Minoru Aoyagi Figure 1 Figure 2 w'W. - Figure 3 Figure 5 Figure 6 zzrf also...1v I11

Claims (1)

[Scope of Claims] A large number of iron cores around which excitation coils are wound are arranged around the center of the print head, and the center of each excitation coil is arranged approximately parallel to the center of the print head, and printing is performed from both ends of each iron core. Extend the yoke toward the center of the head, make vertical through holes at the tips of both yokes, insert the plunger into both holes, and make sure that the plunger is always inserted through the through hole of one yoke. 1. A print head that protrudes through both sides, and is arranged so that the plunger side end of the through hole of the other yoke and the other end of the plunger are in a close positional relationship.