JP2696871B2 - Wire type dot printer head - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire type dot printer head, and more particularly, to a yoke member forming a magnetic path thereof.

[Conventional technology]

2. Description of the Related Art Conventionally, a wire dot printer head that performs impact printing on a print medium via an ink ribbon by selectively protruding a print wire has been widely known. As means for driving the print wire, an armature is provided on a wire drive lever which is engaged with the print wire at one end and is rotatably supported on the other end side as a fulcrum. In general, the rotational displacement caused by the suction is enlarged to operate the printing wire. A magnetic path through which a magnetic flux that generates an electromagnetic attraction force by energizing the exciting coil wound around the coil core is formed by a yoke member provided with the coil core, an amateur, and other yoke members. FIGS. 7 and 8 are a plan view and a cross-sectional view of a yoke member provided with a coil core wound with an exciting coil of such a wire dot printer head. The bottomed cylindrical yoke member 73 includes a cylindrical portion having a uniform thickness on the outer periphery and a coil core 73 disposed on the inner side of the cylindrical portion at a uniform interval on the same circumference.
Has a. An excitation coil 74 wound around a coil bobbin 78 is attached to each coil core 73a. The inner shape of the outer peripheral cylindrical portion of the bottomed cylindrical yoke member 73 is an arc shape as shown in FIG. 7, and the gap between the outer peripheral surface of the exciting coil 74 differs depending on the location. In particular, the exciting coil 74 and the exciting coil 74
The gap between the boundary portion and the outer peripheral cylindrical portion is large.

[Problems to be solved by the invention]

However, in the yoke member 73 shown in FIGS. 7 and 8, there is a portion where the gap between the outer peripheral surface of the excitation coil 74 and the outer peripheral cylindrical portion of the yoke member 73 is large. The heat generated in 74 cannot be efficiently conducted and radiated to the outside of the printer head. For this reason, if the energizing of the exciting coil 74 is repeated, the electric resistance of the exciting coil winding increases and the energizing current value of the exciting coil 74 decreases as the temperature of the exciting coil 74 rises. Electromagnetic attraction sufficient to drive the wire cannot be generated, resulting in poor print quality. Further, when the excitation coil 74 is repeatedly energized, the coating of the excitation coil 74 may be melted and burnt out. In addition, in high-speed driving in which the number of times of energizing the exciting coil 74 per unit time is high,
Since the amount of heat generated in the exciting coil 74 is large, the increase in printing speed has been hindered.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the conventional problems and to provide a wire dot printer head capable of high-speed printing without deteriorating printing quality or burning of an exciting coil.

[Means for solving the problem]

In the wire dot print head according to the present invention, the surface of the yoke member facing the outer peripheral surface of the exciting coil has the same shape as the contour shape of the outer peripheral surface of the exciting coil, and insulation failure does not occur along the outer peripheral surface of the exciting coil. It is characterized by being arranged as close as possible within the range.

〔Example〕

 An embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a side sectional view of a wire type dot printer head according to a first embodiment of the present invention. FIG. 2 is a plan view of a main part of the wire type dot printer head according to the first embodiment of the present invention. In the figure, reference numeral 2 denotes a guide holder, which is a nose portion 2a for holding wire guides 11 and 12, a spring 1
6 is formed integrally with a cylindrical portion 2d for mounting 6, and a guide portion 2f provided with a hole for guiding the wire 10. A yoke member 3 made of a shallow bottomed cylindrical magnetic material is fixed to the outer periphery of the cylindrical portion 2d of the guide holder 2 with its relative position determined by the positioning portion 2b. In the yoke member 3, a plurality of coil cores 3a are integrally formed at positions surrounded by the outer cylindrical portions 3b, 3e, the inner cylindrical portions 3c, 3d, and both cylindrical portions. First
In the figure, on the left side of the yoke member 3, a bottomed cylindrical yoke 5 made of a magnetic material and a disk-shaped side yoke 6 are laminated. A fulcrum shaft 9 which engages the printing wire 10 at one end and penetrates a wire driving lever 7 provided with an armature 8 made of a ferromagnetic material at a position facing the coil core 3a to form a pivot of the wire driving lever 7 is a yoke 5 And is pivoted by a shaft supporting lateral groove 6a provided in the side yoke 6,
Further, a holding plate 14 is placed so as to cover them. These components are integrally connected by a fastening plate 15 spanned between the holding plate 14 and the nose cover 1. The exciting coil 4 is wound around a coil bobbin 18 and each coil core 3a
Attached to. The terminal portion of the exciting coil 4 passes through a hole provided at the bottom of the yoke member 3 and is fixed to the printed wiring board 17 via an insulating plate 25. The drive lever 7 is held in a standby state urged toward the damper 13 by a spring 16 interposed between the drive lever 7 and the cylindrical portion 2d of the guide holder 2.

When a current is applied to one or a plurality of excitation coils 4 selected by a print command signal via the printed wiring board 17 in the wire-type dot printer head thus configured, the excitation coils 4 generate a magnetic flux. This magnetic flux flows from the coil core 3a to the yoke member 3, the bottomed cylindrical yoke 5,
A magnetic path is formed in the order of the side yoke 6, the armature 8, and the coil core 3a to generate an attractive force between the armature 8 and the coil core 3a. As the amateur 8 is attracted to the coil core 3a, the wire drive lever 7 shown in the lower part of FIG.
Rotating clockwise while resisting the urging force of 16, the printing wire 10 held at the tip is driven out toward the platen 21, and the printing wire 20 is contacted with the printing paper 20 via the ink ribbon 19 to perform printing.

FIGS. 3 and 4 are a plan view and a sectional view of a yoke member having a coil core around which an exciting coil is wound according to the first embodiment of the present invention, showing characteristic portions of the present invention. The yoke member 3 is made of a magnetic material having a cylindrical shape with a bottom, and a plurality of coil cores 3a are integrally formed at positions surrounded by the outer cylindrical portions 3b, 3e, the inner cylindrical portions 3c, 3d, and both cylindrical portions. I have. The exciting coil 4 wound around the coil bobbin 18 is attached to each coil core 3a, and the outer cylindrical portions 3b, 3e the inner cylindrical portion 3.
The contour of the surface facing the excitation coil 4 of c, 3d is the excitation coil 4
Along the external shape described above, the metal yoke member 3 and the exciting coil 4 are adjacent to each other as far as possible without causing insulation failure. Outer peripheral cylindrical portion 3b, 3e of yoke member 3
A small gap between the inner peripheral cylindrical portions 3c and 3d and the exciting coil 4 is filled with a filler 22 such as a silicon resin having a high thermal conductivity as a non-metallic material. It is transmitted to the member 3 efficiently.

The function of the yoke member 3 configured as described above will be described. When a current is applied to one or more excitation coils 4 selected by the print command signal via the printed wiring board 17, the excitation coils 4 generate a magnetic flux. This magnetic flux flows from the coil core 3a to the yoke member 3, the bottomed cylindrical yoke 5,
A magnetic path is formed in the order of the side yoke 6, the armature 8, and the coil core 3a to generate an attractive force between the armature 8 and the coil core 3. That is, if the magnetic resistance of the magnetic path is small, the attractive force can be more efficiently obtained between the armature 8 and the coil core 3. However, the magnetic force is opposed to the exciting coil 4 of the outer cylindrical portions 3b, 3e and the inner cylindrical portions 3c, 3d. Since the surface contours are adjacent to each other along the outer shape of the exciting coil 4, the cross-sectional areas of the outer cylindrical portions 3b, 3e and the inner cylindrical portions 3c, 3d, which are part of the magnetic path, increase, and the Resistance has been reduced. Therefore, electric energy can be more efficiently converted to mechanical energy for obtaining printing power. However, generally, the conversion efficiency of electric and mechanical energy is only a few percent, and it is inevitable that most of the input electric energy is lost as heat in the exciting coil 4. In the wire type dot printer head of the present invention, the surfaces of the outer cylindrical portions 3b, 3e of the yoke member 3 facing the exciting coil 4 have the same shape as the contour of the outer circumferential surface of the exciting coil 4. age,
In addition, the thermal resistance between the exciting coil 4 and the yoke member 3 is low because the insulating coil is arranged as close as possible along the outer peripheral surface of the exciting coil 4 so as not to cause insulation failure. Heat is radiated to the outside of the head via the yoke 3 made of a magnetic material that is a metal having a high rate, and the overheating of the exciting coil 4 is prevented. Therefore, it is possible to realize a wire-type dot printer head capable of high-speed printing without deteriorating printing quality due to overheating of the exciting coil or burning the exciting coil.

FIG. 5 is a sectional view of a yoke member having a coil core around which an exciting coil is wound according to a second embodiment of the present invention. The same as the first embodiment except that the outer cylindrical portion 3b, 3e and the inner cylindrical portion 3c, 3d of the yoke member 3 are formed separately,
It also has a similar effect.

FIG. 6 is a plan view of a yoke member having a coil core around which an exciting coil is wound, showing a third embodiment of the present invention. It is the same as the first embodiment except that the entire outer periphery of the exciting coil 4 is covered with the yoke member 3, and the heat conduction and heat radiation from the exciting coil 4 to the yoke member 3 are further enhanced.

〔The invention's effect〕

In the wire dot printer head of the present invention, as described above, the surface of the yoke member made of a metal magnetic material having a high thermal conductivity, which faces the exciting coil, has the same shape as the contour of the outer peripheral surface of the exciting coil, In addition, the thermal resistance between the exciting coil and the yoke member is low by arranging it as close as possible along the outer peripheral surface of the exciting coil as long as insulation failure does not occur, and the heat generated by the exciting coil easily passes through the yoke. As a result, heat is radiated to the outside of the head to prevent overheating of the exciting coil. For this reason, there is an effect that a wire-type dot printer head capable of high-speed printing can be provided without a risk of deterioration of printing quality or burning of the exciting coil due to overheating of the exciting coil.

Further, since the cross-sectional area of the yoke member cylindrical portion, which is a part of the magnetic path, is increased and the magnetic resistance of this portion is reduced, a wire dot printer head capable of efficiently converting electric energy to mechanical printing energy. There is an effect that can be provided.

[Brief description of the drawings]

FIG. 1 is a side sectional view of a wire type dot printer head showing a first embodiment of the present invention. FIG. 2 is a plan view of a main part of the wire type dot printer head showing the first embodiment of the present invention. FIG. 3 is a plan view of a yoke member having a coil core wound with an exciting coil according to the first embodiment of the present invention. FIG. 4 is a sectional view of a yoke member provided with a coil core wound with an exciting coil according to the first embodiment of the present invention. FIG. 5 is a sectional view of a yoke member provided with a coil core around which an exciting coil is wound, showing a second embodiment of the present invention. FIG. 6 is a plan view of a yoke member having a coil core around which an exciting coil is wound, showing a third embodiment of the present invention. FIG. 7 is a plan view of a yoke member provided with a coil core wound with an exciting coil of a conventional wire-type dot printer head. FIG. 8 is a cross-sectional view of a yoke member provided with a coil core wound with an exciting coil of a conventional wire dot printer head. DESCRIPTION OF SYMBOLS 1 ... Nose cover 2 ... Guide holder 3 ... Yoke member 3a ... Coil core 3b, 3e ... Peripheral cylindrical part 3c, 3d ... Peripheral cylindrical part 4 ... Excitation coil 5 ... Bottom cylindrical yoke 6 ... … Side yoke 7… Wire drive lever 8… Amateur 9… Support shaft 10… Printing wire 11, 12… Wire guide 13… Damper 14… Presser plate 15… Fixing plate 16… Spring 17… ... Wiring board 18 ... Coil bobbin 19 ... Ink ribbon 20 ... Printing paper 21 ... Platen 25 ... Insulating plate

Claims (1)

(57) [Claims] 1. A wire-type dot printer head having a yoke member provided with a coil core wound with an exciting coil, wherein a surface of the yoke member facing an outer peripheral surface of the exciting coil is defined by a contour of an outer peripheral surface of the exciting coil. A wire-type dot printer head having the same shape as that of the exciting coil and arranged as close as possible along the outer peripheral surface of the exciting coil within a range where insulation failure does not occur.