JPH069953U - Wire dot print head - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a wire dot print head in which the armature attraction force of each sub-core does not vary when the electromagnet is energized. [Structure] The sub-core 31 is made to correspond to each electromagnet 12 and is integrally formed in a ring shape having a comb-shaped projection 32.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to the structure of a wire dot print head used in a serial printer or the like.

[0002]

[Prior art]

 The wire dot print head used in conventional serial printers and the like has an armature in which a print wire is fixed to the free end and elastically supported by a leaf spring, and a magnetic circuit that biases the armature in a biased state by the magnetic flux of a permanent magnet. Part, an electromagnet that generates a magnetic flux that cancels the magnetic flux of the permanent magnet during printing operation, and releases the armature from a biased state, and the permanent magnet and the electromagnet that are arranged to face the armature base end portion. There is a sub-core that forms a magnetic path for magnetic flux, and the electromagnet, the sub-core, and the magnetic circuit section are arranged radially in this order on a disk-shaped base plate. The structure and the printing operation of such a conventional wire dot print head will be described below with reference to the drawings.

FIG. 6 is a one-sided sectional view showing an example of the configuration of a conventional wire dot print head.

In FIG. 6, below the guide nose 1 and the guide frame 2 for fixing the guide nose 1, a leaf spring 3 and an armature 4 fixed to the leaf spring 3 are arranged. A print wire 5 is attached to the free end of the armature 4. The printing wire 5 is guided by the wire guide 6 fitted in the opening of the guide nose 1 during the printing operation. The armature 4 is loosely fitted in the groove of the armature yoke 7. A spacer 8 is provided on the lower surface of the leaf spring 3, and a permanent magnet 10 is attached to the lower portion of the spacer 8 via a side yoke 9. The permanent magnet 10 is carried by a base yoke 11. The magnetic circuit portion 23 includes the armature yoke 7, the leaf spring 3, the spacer 8, the side yoke 9, the permanent magnet 10, the base yoke 11, and the base plate 19.

An electromagnet 12 is arranged below the leaf spring 3 on the base yoke 11. The electromagnet 12 is composed of a core 13 integrally attached to the base yoke 11, and a coil 15 wound around a coil bobbin 14 and attached to the core 13. The coil bobbin 14 is provided with terminals 16 to which both ends of the coil 15 are connected, and these terminals 16 are connected and fixed to the board 17 by soldering. A sub-core 18 is arranged between the permanent magnet 10 and the electromagnet 12, and the sub-cores 18 are fixed one by one on the base plate 19 so as to face the base end of each armature 4.

The wire dot print head 20 has a plurality of print elements for one dot arranged radially in a number corresponding to the number of print dots, and includes the armature 4, the print wire 5, the electromagnet 12, and the sub core 18. Except for this, multiple parts are integrally formed and assembled. A cooling fin 21 is arranged below the base plate 19, and the cooling fin 21 and the guide frame 2 are integrally held by a clamp spring 22.

Next, the operation of the wire dot print head having the above configuration will be described.

In the non-printing state, the magnetic flux generated by the permanent magnet 10 is magnetically permeable to all of the base yoke 11, the core 13, the leaf spring 3, the armature 4, the armature yoke 7, the spacer 8 and the side yoke 9. A magnetic closed circuit is formed which returns to the permanent magnet 10 again through the magnetic path consisting of the following. The armature 4 fixed to the leaf spring 3 is biased in the direction of the electromagnet 12 and attracted to the core 13 by the action of the magnetic closed circuit. It becomes a biased state.

During printing, by energizing the electromagnet 12 by energizing the coil 15, a magnetic flux in the direction opposite to the magnetic flux of the permanent magnet 10 passing through the core 13 is generated, and the two magnetic fluxes cancel each other out. Therefore, the armature 4 is released from the suction state (biased state). By releasing the suction of the armature 4, the armature 4 is separated from the core 13 by the spring force of the leaf spring 3. Then, as the armature 4 rotates, the gap between the base end and the sub core 18 is narrowed, the magnetic flux of the electromagnet 12 and the magnetic flux of the permanent magnet 10 increase in the sub core 18, and the force of attracting the armature 4 to the sub core 18 also increases. .

As a result, the rotational force of the armature is increased, and the marking wire 5 fixed to the tip of the armature 4 projects from the wire guide 6 at a high speed, and the ink ribbon (not shown) and the printing medium are pressed against the platen to cause the dots to move. Print. The energization of the coil 15 of the electromagnet 12 is cut off, and the armature 4 is attracted to the core 13 again, thus completing one printing operation.

When the adjacent electromagnets 12 of the wire dot print head 20 are simultaneously energized, most of the magnetic flux generated by the coil 15 flows through the core 13 and the armature 4 into the respective sub-cores 18, and the coil 15 Since a magnetic circuit is formed between and, the magnetic resistance is reduced as a whole, and the magnetic flux flowing into the adjacent core 13 is reduced. That is, the magnetic interference when the adjacent electromagnets 12 are simultaneously energized is reduced, and the input energy in anticipation of the magnetic interference can be reduced, so that the copper loss and the iron loss are also reduced.

[0012]

[Problems to be solved by the device]

 In the conventional wire dot print head, since the sub-cores are individually attached to the base plate, the height of the surface facing the base end of the armature varies, and when the electromagnet is energized, the armature suction of each sub-core will occur. There is a problem in that there is a difference in force, and therefore a difference in the printing force of each wire, which causes uneven printing density.

An object of the present invention is to provide a wire dot print head that does not cause a difference in the armature attraction force of each sub core when the electromagnet is energized.

[0014]

[Means for Solving the Problems]

 In order to solve the above-mentioned object, in the wire dot print head of the present invention, the sub core is made to correspond to each electromagnet and is integrally formed in a ring shape having a comb-shaped projection.

[0015]

[Action]

 When the electromagnet of the wire dot print head configured as described above is energized, the sub-core is arranged with a certain gap from the base end of the armature, so that the same amount of magnetic flux from each armature base to the sub-core. Flowing. As a result, the armature suction force of each sub-core becomes equal, and each wire prints with the same printing force.

Therefore, according to the present invention, when the electromagnet is energized, there is no difference in the armature attraction force between the sub-cores.

[0017]

【Example】

 An embodiment of the present invention will be described with reference to the drawings. Note that the same reference numerals are given to elements common to each drawing.

FIG. 1 is a half sectional view showing an embodiment of the present invention, FIG. 2 is a perspective view showing an essential part of the present invention, and FIGS. 3 and 4 are sectional views taken along the line AA of FIG. FIG. 5 is a perspective view showing a modified example of an embodiment of the present invention.

The present embodiment is different from the conventional example in that the sub-core is integrally formed in a comb-like shape and a ring shape corresponding to each electromagnet.

As shown in FIG. 2, the sub-core 31 located at the position facing the base end of the armature 4 in FIG. 1 has the same number of protrusions 32 as the printing elements integrally formed on the upper portion of the C ring in the shape of a comb tooth. is there. The sub-core 31 has a notch 35 having chamfers 33 and 34 at its ends 51 and 52 and a notch 36 having a U-shape, and its outer diameter is the same as or slightly larger than the inner circumference of the base yoke 37. Is formed. Protrusions 38 and 39 are provided on the inner circumference of the base yoke 37, and semicircular cutouts 40, 41, 42 and 43 are provided on both sides. Further, there are provided contact surfaces 45, 46, 47, 48, 49, 50 which come into contact with the outer peripheral surface 44 of the sub core 31 when the sub core 31 is press fitted into the base yoke 37.

The width of the cutout portion 35 of the sub core 31 is slightly narrower than the width of the convex portion 39 of the base yoke 37. Therefore, when the sub-core 31 is press-fitted into the base yoke 37, the chamfered portions 33 and 34 come into contact with the convex portions 39, and the ends 51 and 52 of the sub-core 31 are in the directions of arrows B and B'as shown in FIG. Spread to. As shown in FIG. 4, the corner portions 53 and 54 are blocked by the notches 42 and 43, respectively, and the sub core 31 is fixed to the base yoke 37.

Since the sub-core 31 is integrally machined from a single plate, the height of each protrusion 32 from the base plate 19 is uniform.

The components other than the sub core 31 and the base yoke 37 in the wire dot print head of the present invention are the same as those in the conventional example, and thus the description thereof will be omitted.

Next, the operation of the wire dot print head having such a configuration will be described.

In the non-printing state, the magnetic flux generated by the permanent magnet 10 is magnetically permeable to all of the base yoke 37, the core 13, the leaf spring 3, the armature 4, the armature yoke 7, the spacer 8 and the side yoke 9. A magnetic closed circuit is formed which passes through the magnetic path consisting of and returns to the permanent magnet 10 again. By the action of this magnetic closed circuit, the armature 4 fixed to the leaf spring 3 is biased toward the electromagnet 12 and attracted to the core 13. It becomes a biased state.

During printing, by exciting the electromagnet 12 by energizing the coil 15, a magnetic flux in a direction opposite to the magnetic flux of the permanent magnet 10 passing through the core 13 is generated, and the two magnetic fluxes cancel each other out. Therefore, the armature 4 is released from the suction state (biased state). By releasing the suction of the armature 4, the armature 4 is separated from the core 13 by the spring force of the leaf spring 3. Then, as the armature 4 rotates, the gap between the base end portion and the sub core 31 is narrowed, the magnetic flux of the electromagnet 12 and the magnetic flux of the permanent magnet 10 increase in the sub core 31, and the force of attracting the armature 4 to the sub core 31 also increases. . At this time, the height of each protrusion 32 from the base plate 19, that is, the distance between the base end of the armature 4 and the upper surface of the protrusion 32 is uniform, and the magnetic resistance is also uniform. The same amount of magnetic flux flows between the portion and the protrusion 32.

As a result, the printing wire 5 fixed to the tip of each armature 4 protrudes from the wire guide 6 at the same speed, and the ink ribbon and the printing medium (not shown) are pressed against the platen to perform dot printing. When the coil 15 of the electromagnet 12 is de-energized and the armature 4 is again attracted to the core 13, one printing operation is completed.

FIG. 5 shows another embodiment of the present invention. In this embodiment, the sub-core 55 may be integrally formed on one side of the O-ring, and the base yoke 56 may be formed in the O-ring so that the inner peripheral surface of the base yoke 56 conforms to the outer shape of the sub-core 55. In this case, the sub core 55 and the base yoke 56 are fixed by bonding or welding. As a result, the base yoke 56 does not have to be processed, and therefore the manufacture is easy.

The components other than the sub-core 55 and the base yoke 56 in the wire dot print head according to another embodiment of the present invention and the operation thereof are the same as those of the one embodiment, and thus the description thereof will be omitted.

[0030]

[Effect of device]

 Since the present invention is configured as described above, it has the following effects.

That is, since the sub-cores are integrally formed in a ring shape, when the electromagnet is energized, variations in the armature attraction force of the sub-cores are prevented and the printing quality is improved.

Furthermore, since the sub-core is integrally processed from a single plate, the manufacturing cost is significantly reduced.

Furthermore, if the sub-core is press-fitted into the base yoke, the steps of bonding or welding when fixing can be reduced.

[Brief description of drawings]

FIG. 1 is a side sectional view showing an embodiment of the present invention.

FIG. 2 is a perspective view showing a main part of the present invention.

FIG. 3 is a cross-sectional view taken along the line AA of FIG. 2 when the sub core is press-fitted.

FIG. 4 is a cross-sectional view taken along the line AA of FIG. 2 when the sub core is press-fitted.

FIG. 5 is a perspective view showing a modified example of the embodiment of the present invention.

FIG. 6 is a one-sided cross-sectional view showing a configuration example of a conventional wire dot print head.

[Explanation of symbols]

 3 leaf spring 4 armature 5 printing wire 10 permanent magnet 12 electromagnet 18, 31, 55 sub core 19 wire dot printing head 20 base plate 32 protrusion

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical indication location H01F 3/12 4231-5E 9211-2C B41J 3/10 114 Z (72) Inventor Masayuki Ishikawa Tokyo 1-7-12 Toranomon, Minato-ku Oki Electric Industry Co., Ltd.

Claims (2)

[Scope of utility model registration request] 1. An armature in which a printing wire is fixed to a free end and is elastically supported by a leaf spring, a magnetic circuit unit for biasing the armature in a biased state by a magnetic flux of a permanent magnet, and the permanent magnet during a printing operation. An electromagnet that generates a magnetic flux that cancels the magnetic flux due to, and releases the armature from a biased state; and a sub-core that is arranged to face the armature base end portion and forms a magnetic path for each magnetic flux of the permanent magnet and the electromagnet, Electromagnet, sub-core,
A wire dot print head radially arranged on a base plate in the order of magnetic circuit parts, characterized in that the sub-core is formed integrally with each electromagnet in a ring shape having a comb-shaped projection. . 2. The sub-core is integrally processed from a single plate,
2. The wire dot print head according to claim 1, wherein the wire dot print head is bent in a C-ring shape and is partially provided with a yoke press fit or a notch for positioning.