JPH0716437Y2 - Wire dot print head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a wire dot print head used in a serial printer, and in particular, a wire dot capable of driving a print wire with low power consumption while suppressing heat generation. The present invention relates to the structure of a print head.

[Conventional technology]

The leaf springs are bent by attracting a plurality of armatures, each having a print wire attached to the front end and having a rear end supported by a leaf spring, to the side of the plurality of electromagnets consisting of a core and a coil by the magnetic force of a permanent magnet. The magnetic flux of the permanent magnet is canceled by selectively exciting the coil, and the restoring force of the leaf spring at this time drives the printing wire together with the armature to print dot characters on a medium such as paper, which is a so-called spring charge type. Wire dot print heads are widely used in serial printers as relatively inexpensive printing means.

In this spring-charge type wire dot print head, there is a phenomenon called magnetic interference in which the leakage magnetic flux of an electromagnet that cancels the magnetic flux of a permanent magnet flows into the adjacent armature and core to change the magnetic flux of the core.

In this case, as the number of print wires that print at the same timing increases, the change in magnetic flux due to magnetic interference increases,
Therefore, when the armatures are released, a larger exciting current is required than in the case where the armatures are operated independently, which leads to an increase in power consumption, that is, an increase in heat generation amount of the head.

Also, in this type of print head, the change in the excitation current also affects the operation of the armature after release, so control such as changing the energization time to the coil according to the number of print wires that print at the same timing is possible. is necessary.

Therefore, in the future, in order to realize higher speed, higher print output, lower power consumption, further size reduction, and higher density mounting of the spring charge type wire dot print head, in order to achieve this, the magnetic It can be said that an increase in power consumption and an increase in heat generation due to interference are one of the most important problems that cannot be avoided.

Therefore, various improved techniques have been proposed in order to solve this problem. Among them, the technique disclosed in Japanese Patent Laid-Open No. 58-96568 discloses that the directions of magnetic fluxes passing through adjacent cores are opposite to each other. Attention is paid to the fact that the above-mentioned magnetic interference is opposite to the conventional one.

The technique will be described below with reference to FIGS. 6 to 8 as a conventional example.

FIG. 6 is a sectional view of a conventional wire dot print head, FIG.
The figure is a sectional view taken along the line AA of FIG.

In the figure, reference numeral 1 denotes a circular (ring-shaped) rear frame formed of a non-magnetic material such as aluminum, and 2 denotes L-shaped cores arranged independently on the rear frame 1 in a centripetal manner. Coil 3 around the raised tip of 2
The electromagnets 4 are formed by winding the magnets, and the permanent magnets 5 are laminated on the rear portions of the cores 2. The permanent magnets 5 are adjacent to each other and have polarities opposite to each other. Are arranged so that

6 is an intermediate yoke laminated on each permanent magnet 5, 7 is a leaf spring in which a fixed end (rear end) is placed on the intermediate yoke 6 and a free end (tip) is arranged in a centripetal direction, and 8 is a rear end. An armature fixedly supported at the free end of the spring 7, 9 is a front yoke arranged on the leaf spring 7, 10 is a front frame provided on the front yoke 19, and the front frame 10 is made of aluminum. And a wire guide 11 at the tip of the protrusion provided in the center.

Reference numeral 12 is a printing wire fixed to the free end of each leaf spring 7, and the tip of each printing wire 12 is aligned in a predetermined arrangement by the wire guide 11 so as to project toward a medium such as a sheet (not shown). ing.

13 is the intermediate yoke 6 laminated on the permanent magnet 5 as described above,
A fixing screw that integrally fixes the leaf spring 7, the front yoke 9, and the front frame 10. The fixing screws 13 are fastened in the same number as the components such as the leaf spring 7 and the like, so that each component is integrally assembled. Has been.

Next, the operation of the dot print head having the above-described configuration
It will be described with reference to the drawings.

FIG. 8 is a perspective view of the main part of the wire dot print head.
Here, two sets of magnet assemblies (a) and (b) are shown.

First, since the electromagnet 4 is not excited during non-printing, in the magnet assembly (a), the magnetic flux of the permanent magnet 5 is as shown by the arrow a, the intermediate yoke 6, the front yoke 9, and the armature.
8, and forms a loop through the core 2 and back to the permanent magnet 5, and in the magnet assembly (b), the permanent magnet 5
The magnetic flux of the core 2, the armature 8,
A loop returning to the permanent magnet 5 through the front yoke 9 and the intermediate yoke 6 is formed.

That is, since the electromagnets 5 of the magnet assemblies (a) and (b) are arranged so that the polarities thereof are opposite to each other, the directions of the loops of the magnetic flux thereof are opposite to each other.

In this case, both of them are the core 2 of the electromagnet 4 and the armature 8
Since a magnetic attraction force is generated between and, the armature 8 to which the print wire 12 is fixed is attracted to the core 2 against the force of the leaf spring 17, and the leaf spring 7 is bent.

Therefore, when printing is performed by driving the print wire 12 corresponding to one magnet assembly (a), the magnet assembly (a)
When the coil 3 of the electromagnet 4 is energized, as shown by the arrow c, the magnetic flux in the direction opposite to the magnetic flux of the permanent magnet 5, that is, the magnetic flux returning to the core 2 through the armature 7, the front yoke 1, and the intermediate yoke 6. A loop is generated, and the magnetic flux in the direction of arrow a cancels the magnetic flux in the direction of arrow a, that is, the magnetic flux of the permanent magnet 5, and the armature 8 attracted to the core 2 is released.

As a result, the leaf spring 7 supporting the armature 8
The printing wire 2 is driven together with the armature 8 by the restoring force, and the tip of the printing wire 2 collides with the printing medium on the platen (not shown) via the ink ribbon (not shown), so that the dot is printed on the printing medium. It

On the other hand, in this printing operation, when the magnetic flux in the direction of the arrow c is generated as described above, the leaked magnetic flux flows through the core 2 of the electromagnet 4 of the adjacent magnet assembly (b) as shown by the arrow d. The magnetic flux in the direction of the arrow d is the direction of the magnetic flux of the permanent magnet 5 in the magnet assembly (b), that is, the arrow b.
This is the magnetic flux in the opposite direction.

Such a leakage magnetic flux also flows through the core 2 of the electromagnet 4 of the magnet assembly (a) when the coil 3 of the electromagnet 4 is energized to drive the print wire 2 of the magnet assembly (b).

Therefore, when energizing the coils 13 of both magnet assemblies (a) and (b) at the same time, the leakage magnetic flux flows into the cores 2 adjacent to each other, whereby the magnetic fluxes of the permanent magnets 15 in the two cores 2 respectively. Since the magnetic flux flows in the opposite direction, the printing wire 12 can be driven only by exciting the electromagnet 4 with a small power consumption, and the heat generation amount of the head also becomes small.

[Problems to be solved by the device]

However, in the above-mentioned conventional wire dot print head, since the permanent magnets corresponding to the respective print wires are independent and the polarities of the adjacent permanent magnets are opposite, the permanent magnets in the non-magnetized state are After assembling the print head using the, the manufacturing process of magnetizing the permanent magnet to the desired strength in a strong magnetic field cannot be taken, and the print head is handled while handling the magnet magnetized to the desired strength in advance. There was a problem that we had to take a complicated and difficult-to-manufacture manufacturing process of assembling.

Further, not only permanent magnets but also leaf springs, intermediate yokes, front yokes, and the like are often present as independent parts, which results in an increase in product cost.

The present invention has been made to solve these problems, and an object thereof is to realize a wire dot print head which is easy to manufacture, low in cost, and capable of driving a print wire with low power consumption. And

[Means for Solving the Problems]

In order to achieve the above-mentioned object, the present invention has a plurality of armatures arranged in a circular shape so that the print wires are attached to the tips and the tips are oriented in the centripetal direction, and a leaf spring supporting each armature at its free end. And an electromagnet consisting of a core and a coil wound around the core and arranged in a circle corresponding to the armatures. When not printing, the armatures are attracted to the cores of the electromagnets to bend the leaf springs. In the wire dot print head, in which the armature is opened by selectively exciting the coil of the electromagnet at the time of printing, and the restoring force of the leaf spring drives the print wire together with the armature. A back pole made of a magnetic material arranged outside the row,
At least one core of the electromagnets arranged as described above is provided, and a base plate made of a magnetic material provided with a back pole excluding the back pole corresponding to the core, and a core and a back pole fixed to the base plate. A first magnet assembly comprising a core provided on the base plate and a back pole provided on the permanent magnet, and a permanent magnet fixed on the base plate, and provided with a corresponding back pole and a core. And a second magnet assembly comprising a back pole and a core mounted on a permanent magnet.

[Action]

According to the present invention having the above-described structure, the magnetic flux of the permanent magnet for attracting each armature to the core of the electromagnet returns to the permanent magnet through the back pole, the armature, the core, and the base plate in the first magnet assembly. And in the second magnet assembly, forming a loop through the core, armature, back pole, and base plate back to the permanent magnet,
The directions of the magnetic flux loops of the permanent magnets passing through the first and second magnet assemblies are opposite to each other.

Therefore, according to this, it is not necessary to provide an independent permanent magnet corresponding to each armature as in the prior art, and since it can be configured by using one permanent magnet, printing is performed by using a non-magnetized permanent magnet. The manufacturing process can be facilitated by assembling the parts of the head integrally and then magnetizing the permanent magnet to a desired strength in a strong magnetic field.

In addition, since the number of permanent magnets is one, a leaf spring for supporting the armature can be used as an integral type, and a new component such as a back pole is added, but it is provided independently like the conventional permanent magnet. Further, since the parts such as the intermediate yoke and the front yoke can be omitted, the product cost can be reduced and the manufacturing can be performed at low cost.

〔Example〕

 Embodiments will be described below with reference to the drawings.

FIG. 1 is a perspective view of an essential part showing an embodiment of a wire dot printing head according to the present invention, and FIG. 2 is an exploded perspective view of the same embodiment.
FIG. 3 is a front view showing a part of the component removed, FIG. 4 is a sectional view taken along the line II in FIG. 3, and FIG. 5 is a sectional view taken along the line I-II in FIG.

In the figure, 14 is a circular base plate made of a magnetic material, 15 is a core, 16 is a coil wound around the outer periphery of the core 15, and the core 15 and the coil 16 constitute an electromagnet.

Reference numeral 17 is a back pole formed of a magnetic material, 18 is a permanent magnet, 19 is a mounting plate formed of a magnetic material, and in this embodiment, a plurality of cores 15 are arranged in a circular shape. Are arranged outside the row corresponding to each core 15, and these are attached to the base plate 14, the permanent magnet 18 and the attachment plate 19 in the following relationship.

That is, the base plate 14 is provided with mounting holes for cores and back poles, and every other core 15 is inserted and fixed in the mounting holes for cores.
The back poles 17 corresponding to the cores 15 adjacent to the back poles 15 are similarly inserted and fixed in the mounting holes for the back poles every other one.

On the other hand, the mounting plate 19 is also provided with the same mounting holes for the core and the back pole as described above, and is fixed on the base plate 14 as well as the back pole 17 corresponding to the core 15 fixed on the base plate 14. Every other core 15 corresponding to the back pole 17 is inserted and fixed in the core and the mounting holes for the back pole.

The mounting plate 19 is formed so as to have the same outer shape as the permanent magnet 18, and as shown in FIG. 2, the core 15 and the back pole 17 fixed to the base plate 14 are escaped from each other. Holes 20a, 20b and notches 21a, 21b are provided for stacking the permanent magnet 18 and the mounting plate 19 on the central portion of the base plate 14 using the holes 20a, 20b and the notches 21a, 21b. , The cores 15 and the back poles 17 are arranged and fixed in a circular shape as shown in FIG. 3 by fixing them integrally with the screws 22, and in this embodiment, they are fixed to the base plate 14. A first magnet assembly 23a consisting of a core 15 and a back pole 17 mounted on a permanent magnet 18.
And a second magnet assembly 23b is formed which comprises a back pole 17 fixed to the base plate 14 and a core 15 provided on a permanent magnet 18.

The core 15 and the back pole 17 can be formed integrally with the base plate 14 and the mounting plate 19, respectively.

Numeral 24 is a ring-shaped spacer formed of a non-magnetic material such as aluminum and also serving as the outer peripheral surface of the head.
The reference numeral 24 is superposed on the peripheral portion of the base plate 14, and is fixed on the base plate 14 by a screw 25.

Reference numeral 26 is a printing wire, and 27 is an armature having the printing wire 23 fixed to the tip.

Reference numeral 28 is a leaf spring having a plurality of free ends and integrally formed so that each free end faces the centripetal direction, and the armature 27 is fixedly supported on each free end by laser welding or the like.

29 is a circular residual sheet made of a thin metal plate having abrasion resistance, 30 is a head frame made of a non-magnetic material, and a wire guide is provided at the tip of the protrusion formed at the center of the head frame. 31 is provided.

Here, the leaf springs 28 are stacked on the spacers 24 so that the armatures 27 supported at their free ends are located on the corresponding cores 15 and back poles 17, respectively, and the reluctant sheet 29 is provided on each core 15 and each back pole. It is sandwiched between the pole 17 and the free end of the leaf spring 28. A head frame 30 is superposed on the outer periphery of the leaf spring 28, and a screw 32 passed from the side of the head frame 29 is fastened to a screw hole of the spacer 24 to integrally assemble them.

In this assembled state, the tip of each printing wire 26 is positioned and held in a predetermined arrangement by the wire guide 31.

In addition, each armature 27 is preset so as to rotate about the corresponding back pole 17 as a fulcrum, and the residual seat 29 further has a back pole at the rotation fulcrum.
It serves to protect the upper surfaces of the cores 17, the leaf springs 28 and the cores 16.

Next, the operation of the above configuration will be described.

First, when the coil 16 is not energized during non-printing, the magnetic flux of the permanent magnet 4 flows as shown in FIGS. 4 and 5.

That is, as shown in FIG. 4, the second magnet assembly 23
In b, the magnetic flux of the permanent magnet 18 is the core 15, the armature.
27, the back pole 17, and the base plate 14 to form a loop e returning to the permanent magnet 18, and in the first magnet assembly 23a, as shown in FIG. 5, the magnetic flux of the permanent magnet 18 causes the back pole 17, A loop f is formed that returns to the permanent magnet 18 through the armature 27, the core 15, and the base plate 14.

That is, although one permanent magnet 18 is commonly used in this embodiment, the core 15 and the back pole are mounted on the permanent magnet 18.
Since the 17 are arranged alternately as described above, the magnetic flux flows of the permanent magnets 18 in the adjacent magnet assemblies are opposite to each other.

Then, by the magnetic flux of this permanent magnet 18, each armature 27
Is attracted to the core 15 against the force of the leaf spring 28, and is rotated about the back pole 17 as a fulcrum, so that the leaf spring 28 is bent.

Therefore, when the printing wire 26 corresponding to the first magnet assembly 23a of the first and second magnet assemblies 23a and 23b shown in FIG.
When the coil 16 in 23a is energized, a loop of a magnetic flux in a direction opposite to the magnetic flux of the permanent magnet 18 is generated as shown by an arrow g. The magnetic flux in the arrow g direction causes the magnetic flux in the arrow f direction, that is, the permanent magnet 18 to move. Magnetic flux is canceled out, core 15
The armature 27 being sucked into is released.

This allows the leaf spring 28 supporting this armature 27.
The printing wire 26 is driven together with the armature 27 by the restoring force, and the tip of the printing wire 26 collides with the printing medium on the platen (not shown) via the ink ribbon (not shown), so that the dot is printed on the printing medium. It

On the other hand, when a magnetic flux in the direction of arrow g is generated in the printing operation as described above, the leakage magnetic flux causes an arrow to the core 15 fixed on the armature 27 and the permanent magnet 18 of the adjacent second magnet assembly 23b. Flow as indicated by h. The magnetic flux in the direction of the arrow h is generated by the second magnet assembly 23.
This is a magnetic flux in a direction opposite to the direction of the magnetic flux of the permanent magnet 18 indicated by the arrow e in b, that is, the direction of canceling the magnetic flux of the permanent magnet 18.

Such a leakage flux is applied to the armature 27 and the permanent magnet 18 of the adjacent first magnet assembly 23a when the coil 16 is energized to drive the print wire 26 corresponding to the second magnet assembly 23b. Fixed back pole
The same goes for 17.

Therefore, when the coils 16 of the first and second magnet assemblies 23a and 23b adjacent to each other are simultaneously energized, the leakage flux thereof flows into the magnet assemblies adjacent to each other and is added to the excitation magnetic flux of the coil 16. The exciting magnetic flux is increased as compared with the case of exciting 16 alone, and as a result, the inductance of the coil 16 is increased and the current is decreased. Then, it is possible to perform a predetermined printing operation.

That is, in the present embodiment, one permanent magnet 18 is used as a common one, but the flow of magnetic flux of the permanent magnets 18 in adjacent magnet assemblies is made to be in opposite directions. Similar to the configuration in which the polarities of the adjacent permanent magnets are adjacent to each other, the printing can be performed with small power consumption, and the heat generation amount of the head can be reduced.

In the above-described embodiment, when the number of the printing wires 26 is an odd number, the cores 15 cannot be fixed to the base plate 14 and the permanent magnets 18 so as to form a complete alternating arrangement, and the magnetic flux loops of the permanent magnets 18 are formed. Will be in the same direction between adjacent magnet assemblies. Therefore, in this case, the exciting current to the coil 16 is slightly increased as compared with the complete alternating arrangement, but if it is desired to avoid the increase in the exciting current, a dummy core and a coil are installed to form a substantially complete alternating arrangement. You can do it like this.

Further, in the above-described embodiment, the core 15 and the back pole 17
The magnetic fluxes of the permanent magnets 18 are alternately arranged, but it is also possible to alternately arrange the magnetic fluxes of the permanent magnets 18 such that the magnetic flux loops of the permanent magnets 18 are adjacent to each other. There are more things in the same direction, but
Compared to a head having the same direction, increase in power consumption and heat generation due to magnetic interference can be suppressed.

[Effect of device]

As described in detail above, according to the present invention, in the spring-charged wire dot printing wire, magnetic back poles arranged outside the row corresponding to the cores of the electromagnets are arranged in a circle. At least one core of the electromagnet is provided, and a base plate made of a magnetic material provided with a back pole other than the back pole corresponding to the core, a core fixed to the base plate, and a back pole corresponding to the back pole, With a core and a permanent magnet fixed on the base plate,
Forming a first magnet assembly comprising a core provided on the base plate and a back pole provided on the permanent magnet, and forming a second magnet assembly comprising a back pole provided on the base plate and a core provided on the permanent magnet. In order to attract each armature to the core of the electromagnet generated from the permanent magnet, the directions of the loops of the magnetic flux passing through the first and second magnet assemblies are opposite to each other.

Therefore, according to this, it is not necessary to provide an independent permanent magnet corresponding to each armature as in the prior art, and since it can be configured by using one permanent magnet, printing is performed by using a non-magnetized permanent magnet. After the parts of the head are assembled together, a manufacturing process of magnetizing the permanent magnet to a desired strength in a strong magnetic field can be taken, and the manufacturing process can be facilitated.

In addition, since the number of permanent magnets is one, a leaf spring for supporting the armature can be used as an integral type, and a new component such as a back pole is added, but it is provided independently like the conventional permanent magnet. Since the intermediate yoke and the front yoke can be omitted, the product cost can be reduced and the manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 is a perspective view of an essential part showing an embodiment of a wire dot printing head according to the present invention, and FIG. 2 is an exploded perspective view of the same embodiment.
FIG. 3 is a front view with some parts removed, and FIG. 4 is a third view.
Fig. 5 is a sectional view taken along line II, Fig. 5 is a sectional view taken along line I-II of Fig. 3, Fig. 6 is a sectional view of a conventional wire dot printing head, Fig. 7 is a sectional view taken along line AA of Fig. 8, FIG. 8 is a perspective view of a main part of a conventional wire dot print head. 14: Base plate 15: Core 16: Coil 17: Back pole 18: Permanent magnet coil 17: Mounting plate 23a: First magnet assembly 23b: Second magnet assembly 24: Spacer 26: Print wire 27: Armature 28: Leaf spring

Claims (1)

[Scope of utility model registration request] 1. A plurality of armatures, each having a print wire attached to its tip and arranged in a circle so that the tip faces the centripetal direction, a leaf spring supporting each armature at its free end, a core and the core. It is composed of a coil wound around the armature and has an electromagnet arranged in a circle corresponding to each armature.When not printing, each armature is attracted to the core of the electromagnet to bend the leaf spring. In the wire dot print head that opens the corresponding armature by selectively exciting the coil and drives the print wire together with the armature by the restoring force of the leaf spring, it is placed outside the row corresponding to the core of each electromagnet. At least one back pole made of a magnetic material and at least one core of the electromagnet arranged as described above are provided and correspond to this core. A base plate made of a magnetic material provided with a back pole excluding the back pole, a core fixed to the base plate and a back pole and a core corresponding to the back pole, and a permanent magnet fixed on the base plate Forming a first magnet assembly comprising a core provided and a back pole provided on a permanent magnet and a second magnet assembly comprising a back pole provided on the base plate and a core provided on the permanent magnet, and A wire dot printing head characterized in that the directions of the loops of magnetic flux generated from the magnet and attracting each armature to the core of the electromagnet are opposite to each other through the first and second magnet assemblies. .