JPS6229254Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in the arrangement of permanent magnet poles in a print head for a wire dot printer.

FIG. 1 shows an overall schematic diagram of a wire dot printer. A platen 2 is rotatably supported by the frame 1, and is operated via a gear 3 by a line feed drive motor (not shown). Print media 4
is set on platen 2, and sprocket 5a,
Sent in 5b. Carrier 6 is guide shaft 7
and is guided by the feed screw 8. The feed screw 8 is rotated by a space motor 9 via a belt 10, and this rotation causes the carrier 6 to move onto the platen 2.
The space is moved in the direction of arrow a along . The carrier 6 is equipped with a printing head 11. The printing head 11 is provided with a plurality of printing wires and an electromagnetic mechanism for swinging the printing wires, and the electromagnetic mechanism is selectively driven in synchronization with the movement of the carrier 6. The ink ribbon cassette 12 contains an ink ribbon 13, and the ink ribbon 13 runs between the print head 11 and the print medium 4. In this print head 11, a release type and a suction type are generally used as the electromagnetic mechanism for swinging the printing wire, but in the release type, a permanent magnet and an electromagnet are installed in the same magnetic path, and one end of the leaf spring is fixed. Then, a printing wire is connected to the other end, and a permanent magnet normally attracts and bends the leaf spring, and when printing, current is passed through the electromagnetic coil to perform reverse excitation, cutting off the attractive force of the permanent magnet. It swings due to the elastic force of the leaf spring. This operation causes the printing wire to move toward the platen and perform dot printing. When the current in the coil is cut off, the leaf spring is attracted by the permanent magnet and the printing wire returns to its original position. but,
In print heads equipped with multiple electromagnetic mechanisms that operate in this manner, there is a problem in that both the magnetic flux from the permanent magnets and the magnetic flux from reverse excitation of the electromagnetic mechanisms act on other adjacent electromagnetic mechanisms, causing magnetic interference. .
Therefore, a large amount of electric power is required for the electromagnetic mechanism to output a strong magnetic force. Moreover, this increases the amount of heat generated, resulting in an increase in the temperature of the device.Furthermore, the adjustment of the gap between the leaf spring and the magnetic material has the disadvantage of requiring fine adjustment.

The present invention simplifies and miniaturizes the structure of this printing head, consumes less power, and is arranged to form a closed magnetic path between the iron core of the electromagnetic mechanism and the permanent magnet in order to achieve high-speed impact. It is.

For this reason, the present invention uses a leaf spring connected to printing wires, an electromagnet mechanism with an excitation coil wrapped around an iron core,
A plurality of magnetic units each including a permanent magnet that generates a magnetic flux for deflecting the leaf spring and attracting it to the iron core are arranged in a ring, and the magnetic flux of the permanent magnet is used to energize the excitation coil of the electromagnet mechanism. In a release type printing head that cancels out the restraint of the leaf springs, the permanent magnet fixes the leaf springs adjacent to each other, the iron core of the electromagnetic mechanism facing the leaf springs, and one end of the electromagnetic mechanism. The iron cores are arranged so as to form a closed magnetic path through the first substrate, and are magnetized so that the direction of the magnetic flux passing through each core is alternately opposite. It is characterized in that the member constituting a part of the path is disposed so as to face the side surface of the leaf spring with a gap interposed therebetween.

The present invention will be described in detail below with reference to the accompanying drawings.
Figure 2 shows a conventional print head. A is a front view and B is a front view.
-B' is a cross-sectional view, and C is a C-C' cross-sectional view. The permanent magnet 30, the leaf spring 41, and the electromagnetic mechanism 32 are arranged to form part of a magnetic path. Electromagnetic mechanism 32
An excitation coil 32b is wound around the iron core 32a,
The iron core 32a is a disk-shaped first core that forms a part of the magnetic path.
It is attached to the board 33 of the board 33 with a lock pin 43 and machine screws. A permanent magnet 30 is also fixed to the substrate 33, and one end of a fan-shaped leaf spring 41 is fixed to the permanent magnet 30 via a yoke 38 with a screw or the like. A printing wire 35 is attached to the tip of the leaf spring 41.
are connected. A second board 40 is made of a magnetic material and has a projection 42 indicated by diagonal lines, and is fixed together with the leaf spring 41 and the yoke 38 by screws. This second substrate 40 constitutes a part of the side magnetic path.

Now, when the excitation coil 32b of the electromagnet mechanism 32 is not excited, the magnetic flux of the permanent magnet 30 is shifted from the N pole of the permanent magnet 30 to the first substrate 3, as shown in FIG.
3. It reaches the S pole via the iron core 32a of the electromagnet mechanism 32 and the leaf spring 41, forming a seed magnetic path. On the other hand, a part of the magnetic flux of the permanent magnet 30 is transmitted from the N pole to the first substrate 33, the iron core 32a of the electromagnetic mechanism 32, and the leaf spring 4.
1. The protruding portion 42 reaches the S pole via the substrate 40 to form a side magnetic path. Therefore, the leaf spring 41 has a main magnetic path with the leaf spring 41 as a magnetic path, and a second substrate 40.
The magnetic flux E shown by the solid arrow line from the side magnetic path whose magnetic path is
It is adsorbed, bent and restrained.

Next, when the excitation coil 32b of the electromagnet mechanism 32 is excited, the magnetic flux E of the permanent magnet 30 is canceled by the reverse magnetic flux D indicated by the dotted arrow, so that the leaf spring 41
restrictions will be lifted. Therefore, the leaf spring 41 swings to return to its normal state, and as a result, the printing wire 35 connected to the leaf spring 41 moves toward the platen, and its tip presses the printing paper against the platen via an ink ribbon or the like. . Therefore, the reverse magnetic flux D of the excitation coil 32b cancels out the reverse excitation of the adjacent excitation coil 32b. Therefore, when excitation is performed at the same time, it is necessary to increase the excitation force by the amount consumed by magnetic interference, which has the disadvantage of increasing power consumption and heat generation.

Fig. 3 shows an embodiment of the printing head according to the present invention.
It is a C′ cross-sectional view. Parts that are the same as those in Figure 2 are given the same numbers. The major difference from the print head in FIG. 2 is that a permanent magnet is fixed to the hatched area of the second substrate 50, which corresponds to the conventional protrusion 42, and is therefore fixed to the first substrate 33. The permanent magnet 30 is removed and the shape is changed as shown in the first substrate 52. The permanent magnet 51 has magnetic poles N,
It is arranged so that S is the same as the magnetic pole of the adjacent permanent magnet 51. Therefore, when the excitation coil 32b of the electromagnet mechanism 32 is not excited, the magnetic flux of the permanent magnet 51 is distributed from the N pole of the permanent magnet 51 to the plate spring 41, the iron core 32a of the electromagnet mechanism 32, and
The iron core 32a of the electromagnet mechanism 32 on both sides adjacent to each other via the first board 52, the leaf spring 41, and the permanent magnet 5
It reaches the S pole of 1 and forms a magnetic path. Therefore,
The leaf spring 41 is attracted by the magnetic flux E shown by the solid arrow line, and is bent and restrained. Next, the electromagnet mechanism 32
When the excitation coil 32b is excited, the magnetic flux E of the permanent magnet 51 is canceled by the reverse magnetic flux D shown by the dotted arrow line, so that the restraint of the leaf spring 41 is released.
Therefore, since the magnetic fluxes E of the adjacent permanent magnets 51 are in opposite directions in the iron core 32a, the electromagnet mechanism 3
Similarly, the reverse magnetic flux D due to 2 is excited in the opposite direction to the adjacent electromagnetic mechanism 32. Therefore, even if adjacent electromagnetic mechanisms 32 are excited simultaneously, the conventional magnetic interference acts in a direction that helps reverse excitation between adjacent electromagnetic mechanisms.
Thereby, the power consumption of the electromagnetic mechanism 32 can be reduced, and the amount of heat generated can also be reduced. Furthermore, there is an advantage that the adjustment of the gap between the leaf spring 41 and the iron core 32b is relaxed compared to the conventional method.

As explained above, in the present invention, the second substrate 50
A permanent magnet 51 is fixed to the adjacent permanent magnet 51.
The adjacent magnetic poles N and S are arranged so that they are the same, and therefore, the excitation by the electromagnetic mechanism 32 is such that the direction of magnetic flux is alternated between adjacent magnetic poles. As a result, even if adjacent electromagnetic mechanisms 32 are excited at the same time, the power consumption and heat generation amount of the electromagnetic mechanisms 32 can be reduced compared to the conventional case. Furthermore, there is an advantage that the adjustment of the leaf spring 41 is eased.

Note that the arrangement position of the permanent magnets 51 is not limited to being arranged between the leaf springs 41 as shown in FIG.
It is sufficient to form a closed magnetic circuit like this, and the installation location does not matter. FIG. 3C shows one of the embodiments.

[Brief explanation of the drawing]

Figure 1 is an overall schematic diagram of a wire dot printer.
Figure 2 shows a conventional print head. A is a front view and B is a front view.
FIG. 3 shows a front view of the print head according to the present invention, B shows a sectional view along B-B', and C shows a sectional view along C-C'. In the figure, 30, 51 are permanent magnets, 32 is an electromagnetic mechanism, 41 is a leaf spring, 33, 52 is a first board, 40 is a second board, 32a is an iron core, 32b
indicates an electromagnetic coil, and 35 indicates a printing wire.

Claims (1)

[Scope of Claim for Utility Model Registration] A leaf spring connected to printing wires, an electromagnetic mechanism having an excitation coil wound around an iron core, and a permanent magnet that generates magnetic flux to bend the leaf spring and attract it to the iron core. In a release type printing head, a plurality of magnetic units consisting of a permanent magnet are disposed in a ring, and the magnetic flux of the permanent magnet is canceled by energization of an excitation coil of an electromagnetic mechanism to release the restraint of the leaf spring. The magnets 51 are attached to the leaf springs 4 adjacent to each other.
1, the iron core 32a of the electromagnet mechanism 32 facing the plate spring, and the first substrate 52 that fixes one end of the electromagnet mechanism to form a closed magnetic path, and magnetic flux passing through each core. are magnetized so that the directions are alternately opposite, and between each leaf spring, a member constituting a part of the closed magnetic path is arranged so as to face the side surface of the leaf spring with an air gap interposed therebetween. A printing head for a wire dot printer characterized by: