JPS62249755A - Wire dot head - Google Patents

Abstract

PURPOSE:To save labor in polishing an end face of a yoke, enhance the rate of heat conduction to the cover side and reduce frictional resistance on a wire, by a construction wherein a bottom surface of a cup form yoke is recessed at a part corresponding to a connecting cable as compared to the other part, and the other part makes contact with a front cover. CONSTITUTION:In a yoke 4, a surface 4B making contact with a flexible cable 19 is recessed from a surface 4A making contact with a front cover 1, and the cable 9 is fitted on the surface 4B. A recessed part of the cover and the recessed part of the yoke 4 define a space for containing the cable 19 and a terminal 18 of a bobbin 17. Therefore, a polishing area in polishing an end face of the yoke 4 is small, and labor can be greatly saved. The surface roughness and the deviation from plane surface of the polished surface can be reduced, and the rate of heat conduction to the front cover 1 side is increased. In addition, since positional accuracy of the front cover 1 and the yoke 4 is enhanced, frictional resistance exerted on a wire 10 by guides can be greatly reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a wire dot head that prints by projecting a plurality of wires.

[Prior art]

FIG. 9 shows a cross-sectional view of a conventional wire dot head.

In the figure, 100 is a main yoke, which has a coil core 102 around which a coil 101 is wound. There is an auxiliary yoke 103 on the upper surface of the main yoke 100, and this auxiliary yoke 103
A post 104 is fitted into the hole. This post 104
An armature lever 105 is swingably supported,
The movable core 106 is attracted to the coil core 102, and the wire 107 is projected.

[Problem that the invention seeks to solve]

In the above configuration, the entire surface of the yoke 100 that is in contact with the flexible cable 108 is flat. The front cover 109 contacts this surface, and the coil 10
A portion of the heat generated from the coil core 102 is conducted to the front cover 109 side. If heat conduction from the yoke 100 to the front cover 109 side is poor at this time, the coil 101
becomes abnormally high temperature, the coating of the coil 101 melts, and the wire dot head is destroyed. Therefore, in order to improve the thermal conductivity from the yoke 100 to the front cover 109 side, both surfaces where the yoke 100 and the front cover 109 are in contact must be polished. Also, the tip guide 110. The sliding resistance between the intermediate guides 111, 112, etc. and the wire 107 is as follows:
It is determined by the state of connection between the yoke 100 and the front cover 109.

Therefore, in order to connect the yoke 100 and the front cover 109 as designed, it is necessary to
Both sides in contact with 9 must be polished. However, in the conventional yoke 100 having such a shape, the polishing surface is large, so the polishing process takes a long time and the cost of the yoke 100 is high.

[Means for solving problems]

The bottom surface of the cup-shaped yoke is made into a recessed part where the part corresponding to the connection cable is depressed compared to other parts, and the other part is brought into contact with the front cover.

[Effect]

With the above-described configuration, the bottom surface of the yoke and the front cover come into contact with each other at a portion other than the connection cable.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The basic structure and operation of an embodiment of the wire dot head of the present invention will be explained below with reference to the accompanying drawings.

Fig. 1 is a front view of the wire dot head, Fig. 2 is a side view thereof, Fig. 3 is a rear view thereof, Fig. 4 is a plan view thereof, and Fig. 5 is a sectional view taken along line A-A in Fig. 1. FIG. 6 and FIG. 7 are views of the rear surfaces in the order of assembly in the direction of FIG. 3, and FIG. 8 is an exploded perspective view. In FIG. 1, reference numeral 1 denotes a front cover, which is made of die-cast aluminum, has radiation fins 2, and has a U-groove 1a for fixing to the main body with screws. The front cover 1 is fixed to the yoke 4 with screws 3.

On the back side of this yoke 4, a rear cover 5 made of a material with high heat dissipation such as aluminum is attached with screws 6.
It is fixed at . After this, the cover 5 is also provided with heat radiation fins 7 as shown in FIG.

As shown in FIG. 5, the front cover 1 includes a recess 1b, a groove 1c, and a
A distal guide 11.degree. groove 1c is provided in the recess 1b, and an intermediate guide 12.13 is fitted and fixed in the recess 1b. The tip guide 11 is an important member that affects printing quality, and must have excellent wear resistance.In this print head, glass ceramic is used, and the surface has a thickness of 1 to 2 μm.
Coated with titanium nitride. Since this print head is a 1.8-bin print head, this tip guide 1
1 is provided with two rows of 9 holes in a staggered arrangement, and the wire diameter is 0.25 mm, so the guide hole diameter is 0, 2.
It is 7 mm.

Also, intermediate guide 12. 13 is also an important member for stabilizing the behavior of the wire 10, and in this print head, it consists of a mold. Reference numeral 4 denotes a cup-shaped yoke, which is an important member in the magnetic circuit, and is made of 3% silicon steel with excellent magnetic properties.It is precision-coated with 18 coil cores 14 arranged in a ring inside the cylindrical wall 4a. It is integrally formed by casting, and the outer cylindrical wall 4a of the yoke 4 and the end surface of the core 14 are on the same plane. Furthermore, the cylindrical wall 4a of the yoke 4 has a shape that also serves as a heat dissipation fin, and the surface of the yoke 4 is coated with black electrodeposition to improve the dielectric strength around the core 14 and heat dissipation. Surface in contact with front cover 1, spacer 15 to be described later
The surface in contact with the core 14 and the end surface of the core 14 are electrodeposited and polished, and then nickel plated to ensure electrical continuity throughout the print head. A bobbin 17 on which a copper wire 16 is wound is inserted into the core 14, and two terminals 18 are press-fitted into the bobbin 17, and these two terminals are in the form of a plate. It is soldered. The bobbin 17 is made of PBT containing 10% glass fiber, which has excellent heat resistance. This terminal 18 is soldered to a flexible cable 19, and a copper wire 1 is connected from the flexible cable 19.
It has the role of supplying current to 6. A spacer 15 made of pure iron is placed on top of the yoke 4, and a disk-shaped auxiliary yoke 20 is placed on top of the spacer 15.

Eighteen bosses 21 are press-fitted into the auxiliary yoke 20, and a subbody 24, which is a mold, is integrally formed by outsert molding. This subbody 24 holds the armature return spring 22 in the hole 24a,
It also guides an armature lever (swinging lever) 23, which will be described later, and further supports the base of the wire 10 brazed to the armature lever 23 by an oblong guide hole 24b, and the armature lever 23 and the inner edge 24
Abutting at point c defines the forward position of the wire.

The auxiliary yoke 20 is a member constituting a magnetic circuit,
It is made of pure iron, and the post 21 is made of nitride stainless steel with excellent wear resistance. A shield film 25, which is a ring-shaped film with holes that fit into the 18 posts 21, is installed on the auxiliary yoke into which the 18 posts 21 are press-fitted, and is made of polyimide with excellent wear resistance. Become. An armature lever 23 is installed on the shield film 25, a movable core 26 is integrated with the armature lever 23 by caulking, and a wire 10 is attached to one end.
is fixed by brazing, and a boss 2 is attached to the other end.
There is a hole that fits into 1. The armature lever 23 is made of a highly rigid SK material to ensure stable operation, and the movable core 26 is made of pure iron because it is an important member constituting the magnetic circuit. Here, the magnetic circuit is the coil core 14. York 4. Spacer 15° Auxiliary yoke 20
．． The movable core 26 forms a closed magnetic path.

That is, when the copper wire 16 is energized, a magnetomotive force is generated, and the movable core 26, which is the movable part of the closed magnetic circuit, is attracted in the direction of the coil core 14, so the armature lever 23 rotates about the fitting part with the post 21 as a fulcrum. Then, the wire 10 fixed to the armature lever 23 moves in the direction of the page (not shown) to print dots, and after printing, the armature return spring 2 returns to the standby state.
Return by 2.

The stop portion at the time of return is the stopper 27. This stopper is made of rubber and is integrated with the stopper fitting 28 by baking. Print head internal temperature ranges from 0℃ to 120℃
Therefore, the material of the stopper 27 is an elastic body that has excellent heat resistance and low rebound resilience, which affects the stability of the operation of the wire 10. In addition, in order to minimize the temperature dependence of the stopper's rebound resilience, the rubber thickness has been made thin (0.
, 2 mm. On the other hand, the stopper metal fitting 28 is made of zinc, which has high vibration damping properties, in order to suppress the impact noise generated when the stopper 27 and the armature lever 23 collide. Since the stroke of the wire 10 in the backward direction is determined by the position of the stopper 27, the stroke adjusting washer 29 is attached to the subbody 2 of the molded part of the auxiliary yoke 2o.
1 and is adjustable in units of 0 and 02 mm. This stroke adjustment washer is made of phosphor bronze. A stroke film 3o is installed on the amateur lever 23, and the amateur lever 23 is pressed from above by an amateur presser spring 31, and the post 21
The amateur lever 23 rotates around . The amateur presser spring 31 is made of stainless steel, and the amateur lever 23
If the armature lever 23 comes into direct contact with the armature lever 23, it will wear out, so the stroke film 3o has a function to prevent this. On the other hand, since the armature lever 23 and the stopper 27 are made of rubber, the armature lever 23 and the stopper 27 tend to stick together, which may cause printing defects, so a stroke film 3o is interposed between the armature lever 23 and the stopper 27 to prevent this. ing. In this way, the stroke film 30 has
It has two functions: preventing the armature lever 23 from being worn out by the armature presser spring 31, and preventing printing defects due to adhesion between the armature lever 23 and the stopper 27.

The amateur presser spring 31 is connected to the stopper fitting 28 and the damper 3.
2, and is fixed to the subbody 24 with a screw 33 via a damper 32. This damper 32 is made of zinc, which has high vibration damping properties, in order to suppress the impact noise generated when the armature lever 23 collides with the stopper 27. Furthermore, a damper presser spring 34 made of stainless steel is installed on top of the damper 32, and presses the damper 32 with an appropriate pressing force, and the pressing force with this print head is about 3.6 kg. Further, as shown in FIGS. 3 and 4, this damper pressing spring 33 is held down by an aluminum rear cover 5, and the auxiliary yoke 20. It is fixed to the yoke 4 with four screws 6 via a spacer 15. After this, the cover 5 is also painted black to improve heat dissipation. Two parallel pins 35 are press-fitted into the yoke 4, and the core 14 of the yoke 4 and the spacer 12.
The positional relationship between the auxiliary yoke 20 and the rear cover 5 is accurately defined.

Since this print head has a large temperature rise, in order to protect the copper wire 16, a thermistor 36 is embedded in a portion of the yoke 4 with a silicone adhesive having high thermal conductivity.

The front cover 1 is positioned as shown in Fig. 1 (in order to properly position the wire 10 and guides, it is positioned with parallel pins 37 and fixed to the yoke 4 with four screws 3.This print head The flexible cable 19 that supplies current to the
This cable holder 38 is held down by two screws 39.
It is fixed to the yoke 4 with a book (Fig. 8).

Further, in this embodiment, as clearly shown in FIG. 6, the cross-sectional shape of the coil core 14, the cross-sectional shape of the bobbin 17,
The shape of the hole 20c provided in the portion of the auxiliary yoke 13 corresponding to the coil core 14 is approximately an isosceles triangle. Such a triangular shape is reasonable in terms of compactness by mounting the coil core centrally, but in this example, the magnetic field generated by the coil core 14 and the copper wire 16 can be used efficiently. In order to guide the wire effortlessly and smoothly and prevent wear, the orientation of the coil core and the wire guide holes are carefully chosen. That is, as shown in the figure, the bisector 40 of the apex angle of the approximately isosceles triangular coil core 14 coincides with the bisector 40 of the hole 20c of the coil bobbin 17 and the auxiliary yoke 20. Subbody 2 so that it becomes longitudinal on the extension line of the branch line
Four guide holes 24b are arranged, and the longitudinal guide holes 13a of the intermediate guide 13 are also set to be longitudinal on an extension of the bisector, and to form two arcuate rows.

The guide holes 12a of the intermediate guide 12 have a substantially perfect circular shape, and are guided in substantially the same two straight lines as the tip guide 11.

With the wire 10 guiding structure as described above, each wire is guided approximately on the bisector of the apex angle of each coil core, and the sliding resistance of the wire is minimized. In addition, since the center line of the armature lever 23 coincides with this bisector, the magnetic flux emitted from the coil core 14 passes through the armature lever 23 most efficiently, and the magnetic field generated by the copper wire 17 is efficiently absorbed. Can be used.

Next, the principle of printing using the wire 10 will be described in detail.

A bobbin assembly in which copper wire 16 is wound around a bobbin 17 is inserted into the coil core 14 which is a part of the yoke 4, and the yoke 4
A spacer 15 is installed on the end face of the spacer 15, an auxiliary yoke 20 is installed on the spacer 15, and a movable core 26 is installed on the auxiliary yoke 20.
A hole 20c is provided for the purpose, and an insert 21 is press-fitted into one part. On the other hand, a wire 10 is fixed to the tip of the armature lever 23 by brazing, a movable core 26 is integrated with the armature lever 23 by caulking approximately in the center thereof, and a post 21 is attached to the other end of the armature lever 23.
A hole is provided for the amateur lever 23 to be attached to the post 21.
It rotates using the second boss as a fulcrum. When the copper wire 16 is energized, a magnetomotive force is generated, and the resulting magnetic flux is directed to the core 14.
゜Yoke 4. Spacer 15. It passes through the auxiliary yoke 20 and the movable core 26 to form a closed magnetic path. At this time, coil core 1
A suction force is generated between the movable core 26 and the movable core 26, and the movable core 26 is attracted toward the core 14, and as a result, the wire 10 is operated and printing is performed.

FIG. 1O shows details of the yoke 4. The surface 4B of the flexible cable 19 that is in contact with the surface 4A of the yoke 4 that is in contact with the front cover 1 is one step lower, and the flexible cable 1O is attached to the lower surface. Due to the recess in the front cover and the recess in the yoke 4,
A storage space for the flexible cable 19 and the terminal 18 of the bobbin 17 is formed. With such a shape, even when polishing the end face of the yoke 4, the polishing area is small, so that the polishing process can greatly save labor compared to the case where the entire surface of the yoke 4 is polished. In addition, the surface roughness and flatness of the polished surface can be reduced, and the thermal conductivity toward the front cover 1 side is also increased. At the same time, the positional accuracy between the front cover 1 and the yoke 4 is also improved, so that the sliding by the guides of the wire lO Dynamic resistance can also be significantly reduced.

〔effect〕

As mentioned above, by using the present invention, the process of polishing the end face of the yoke can be greatly reduced, the thermal conductivity from the yoke to the front cover is also increased, and the positional relationship between the front cover and the yoke can be adjusted as designed. Can be maintained. Therefore, the sliding resistance of the wire can also be greatly reduced. The concave surface of the yoke also serves as a storage space for flexible connection cables, bobbin terminals, etc. Therefore, by using the present invention, an inexpensive and highly reliable wire tod head can be realized.

[Brief explanation of drawings]

Fig. 1 is a front view of a wire dot head according to an embodiment of the present invention, Fig. 2 is a side view of the head, Figs. 3 and 3 are rear views of the head, Fig. 4 is a plan view of the head, and Fig. 5 is a A sectional view taken along line A-A in FIG. 1, FIGS. 6 and 7 are explanatory diagrams showing the back of the head in an assembled manner, and FIG. 8 is an exploded perspective view of the entire head.
FIG. 9 is a sectional view of a conventional wire dot head, and FIG. 10 is a perspective view of a yoke used in an embodiment of the present invention. l・・・・・・・・・・・・・・・・・・・・・・・・
・・・Front cover, 4・・・・・・・・・・・・・・・
・・・・・・・・・・・・York, 5・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・Rear cover,
10・・・・・・・・・・・・・・・・・・・・・
・・・・・・Wire, 11・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・Tip guide, 1
2.13・・・・・・・・・・・・・・・・・・
・・・Intermediate guide, 14・・・・・・・・・・・・・・・
・・・・・・・・・・・・ Coil core, 15...
・・・・・・・・・・・・・・・・・・・・・・・・
Spacer, 16...
・・・・・・・・・ Copper wire, 17・・・・・・・・・
・・・・・・・・・・・・・・・・・・ Bobbin, 20・
・・・・・・・・・・・・・・・・・・・・・・・・
・ Auxiliary yoke, 21・・・・・・・・・・・・・・・
・・・・・・・・・・・・ Post, 22・・・・・・
・・・・・・・・・・・・・・・・・・・・・Return spring, 23・・・・・・・・・・・・・・・・・・・・・
・・・・・・ Armature lever, 26・・・・・・
・・・・・・・・・・・・・・・・・・・・・ Movable core, 27・・・・・・・・・・・・・・・・・・・・・
・・・・・・Stopper, 31・・・・・・・・・・・・
・・・・・・・・・・・・・・・ Armature presser spring, 32・・・・・・・・・・・・・・・・・・
······· damper.

Claims (1)

[Claims] (1) A roughly cup-shaped yoke with coil cores arranged in an annular shape inside, a coil wound around each coil core, a connecting cable provided on the bottom of the cup-shaped yoke and connected to each coil, and the magnetic force of the coil core. A front cover has a swinging member that is driven to swing and project the wires at the end, and a guide part that is fixed to the bottom side of the cup-shaped yoke in contact with the bottom surface and guides each wire to the projecting end. In the wire dot head comprising: Features a wire dot head.