JPH029971Y2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field This invention relates to a print head attached to an impact type dot matrix printer.

Prior Art Conventionally, for the above types of print heads,
As shown in FIG. 1, the through holes 41a and 41b formed in the forked portion 41 of the holder 40 whose base end is fixed to the print head frame (not shown), and the opposite end 42a of the armature 42 are provided. The expanded diameter portions 43a to 43c of the torsion spring 43 were brazed to the formed through hole 42b, and the armature 42 was rotatably supported with respect to the holder 40.
However, since the width of the expanded diameter portion 43c is narrower than the width of the opposing end portion 42a, the brazing material 4 leaked during brazing joining.
4 was filled between the intermediate portions 43d and 43e and the through hole 42b, which caused a problem in that the spring constant of the torsion spring 43 changed. As a result, the armature 42 could not be rotated by the substantially uniform torque of the torsion spring.

Purpose of the invention In view of the above-mentioned conventional drawbacks, the purpose of the present invention is to provide a print head that has a simple configuration, rotates each armature with a substantially uniform spring force, and is capable of performing printing operations with high printing quality. be.

Example Examples will be described below with reference to the drawings.

As shown in FIGS. 2 and 3, the yoke member 1 forming the magnetic circuit has high saturation magnetic flux density characteristics.
The outer yoke 3 is made of permendile as a Co/Fe alloy, and is located at a distance from the outer yoke 3 having a substantially cylindrical shape, and a large number of yokes 4 are formed at appropriate pitches on substantially the same circumference. It is composed of an inner yoke 2. A solenoid coil 5 is wound around this yoke 4, forming an electromagnet device. A casing 6 is fixed to the rear surface of the outer yoke 3, and an annular permanent magnet 7 and a clamping body 8 are fixedly bonded to the front end surface of the casing 6. on the other hand,
A large number of actuating bodies 9 are screwed to the outer peripheral end of the rear surface of the front yoke 10 in a radial direction corresponding to the arrangement of the yoke 4. This front yoke 10 is positioned with respect to the clamping body 8 by pins (not shown) protruding from the clamping body 8 with each actuating body 9 fixed by screws, and is magnetically attracted by the magnetic force of the permanent magnet 7. has been done. Further, on the rear surface of the front yoke 10, a large number of protrusions 10 protrude between armatures 21 of the actuating body 9, which will be described later.
a is integrally formed to form a magnetic circuit extending from the actuating body 9 to the yoke 4. A guide body 11 having a large number of guide holes 11a arranged in a diamond shape is attached to the center of the front surface of the front yoke 10. This guide body 11 is brazed to the free end of the actuating body 9, and has a printing wire 29 extending substantially linearly.
slidingly guides the printing side edge of the Note that the lead end of each solenoid coil 5 wound around the yoke 4 is soldered to a flexible cable 13 attached to a substrate 12. The electric wire formed in the flexible cable 13 is connected to a solenoid drive device (not shown) within the printer body. As a result, excitation current is selectively supplied to each solenoid coil 5.

Next, the operating body 9 will be explained.

In FIGS. 4 and 5, each operating body 9 includes a holder 20, an armature 21, and a wire holder 2.
8 and a torsion spring 22 that rotatably supports the pivot lever with respect to the holder 20. The base end of the holder 20 is screwed to the outer peripheral end of the rear surface of the front yoke 10, and forked parts 23a and 23b are formed at the distal end thereof. Through holes 24a, 24b are formed in the forked portions 23a, 23b, and both ends of the torsion spring 22 in the axial direction are inserted and fixed therein. In addition, these fork parts 23a, 23
Holes 25a and 25b for placing solder are formed in b to communicate with the through holes 24a and 24b, and pellet-shaped or rod-shaped palladium solder, silver solder, or gold solder is used when joining the holder 20 and torsion spring 22 with brazing. etc. are inserted.

The armature 21 is made of permendile, which is a Co-Fe alloy having high saturation magnetic flux density characteristics. and the forked portion 23a,
A through hole 26 is provided at the opposite end 21a located between 23b and 23b.
is formed, and the axial center portion of the torsion spring 22 is inserted and fixed. At the opening of this through hole 26, a chamfered portion 27 leaving the width of an enlarged diameter portion 22c to be described later.
a, 27b are formed. Further, a wire holder 28 is brazed to the tip of the armature 21. A printing wire 29 tapered from the printing end to the base end is soldered to the distal end of the wire holder 28 .
Incidentally, a mounting hole 21b communicating with the through hole 26 is formed in the opposing end 21a of the armature 21, and the armature 21 and the forked portions 23a, 23b are connected to each other.
A brazing material is inserted when brazing and joining the two. Further, a drilled hole 21c is formed on the tip side of the armature 21, and this drilled hole 21c allows the projection 10 to
The mass of the magnetic circuit is reduced by removing unnecessary extra thickness as part of the magnetic circuit. Further, the wire holder 28 is provided with a hole 28a to reduce its mass.

The torsion spring 22 is made of maraging steel made of extremely low carbon high nickel steel, or precipitation hardening martensitic stainless steel 15-7PH or 17-7PH. The enlarged diameter portions 22a to 2 are provided at both ends and the center in the axial direction to be inserted and fixed into the through holes 24a, 24b and the through hole 26.
2c is formed. Expanded diameter portions 22a, 2 at both ends
2b is a forked portion 23a, 23b as shown in FIG.
The enlarged diameter portion 22c at the center is formed to have a width that matches that of the through hole 26. Further, the intermediate portions 22d and 22e sandwiched between the expanded diameter portions 22a to 22c are
It is formed in a wrapper shape that gradually becomes larger in diameter as it reaches the sides a to 22c. As a result, the torsional stress that acts during the printing operation is reduced to the expanded diameter portions 22a to 22.
This prevents the particles from concentrating on the boundary between c and the intermediate portions 22d and 22e.

Next, the operation of this embodiment will be explained.

As shown in FIG. 6, when joining the holder 20, armature 21, and torsion spring 22 with brazing, each through-hole 24a ,2
4b, 26 and the expanded diameter portions 22a to 22c. The brazing material 30 leaking from the gap between the expanded diameter portion 22c inserted into the through hole 26 adheres to the chamfered portions 27a and 27b formed at the opening of the through hole 26, and is attached to the chamfered portions 27a and 27b formed at the opening of the through hole 26 and the intermediate portion 22d. , 22e. As a result, the torsion spring 22
The spring constant of is maintained approximately constant. the result,
Each torsion spring 22 rotates each armature 21 with substantially uniform torque during printing operation,
It is possible to perform printing operations.

Therefore, in this embodiment, a chamfered portion 2 is provided at the opening of the through hole 26.
By forming 7a and 27b, brazing material 30 leaking from the gap with the expanded diameter part 22c inserted into the through hole 26 during brazing adheres to the chamfered parts 27a and 27b, and the through hole 26 and the intermediate part 22d and 22e, the spring constant of each torsion spring 22 can be maintained substantially constant.

In this embodiment, the opposite end 2 of the armature 21
An enlarged diameter portion 22 is formed at the opening of the through hole 26 formed in 1a.
Although the chamfered portions 27a and 27b are formed with a width of c, as shown in FIG. 50b, and the brazing material 51 leaked during brazing adheres to the counterbore parts 50a and 50b,
A configuration that avoids filling between the through hole 26 and the intermediate portions 22d and 22e may also be implemented. Furthermore, the present invention can be implemented even in a configuration in which a fork is formed at the end of the armature, the opposing end of the holder is positioned between the forks, and the armature is rotatably supported by a torsion spring. .

Effects of the Invention As explained above, the present invention is for a dot printer configured to rotatably support a rotary lever having a printing wire at its tip in a holder via a torsion spring, and to print at the tip of the printing wire. In the print head, holes are formed at opposite ends of the holder and the rotating lever, and in the torsion spring, a portion inserted into each hole is an enlarged diameter portion having a larger diameter than other portions, A simple structure in which the length of each hole in the central axis direction is not longer than the length of the expanded diameter portion in the same direction, and brazing material is filled between each hole and the expanded diameter portion. In a print head for a dot printer configured to rotate a rotary lever by a substantially uniform spring force and print at the tip of a printing wire, a bifurcated end is attached to either one of the opposite ends of the holder and the armature. forming a section and positioning the other end between the forks;
A torsion spring having an enlarged diameter portion having a width smaller than the width of the armature at both ends and a central portion is inserted between each through hole bored in the forked portion and the other end, and the enlarged diameter A simple structure in which the torsion spring is joined to the forked part and the other end at the section, and a chamfered part is formed at the opening of the through hole of the armature, leaving the width of the expanded diameter part of the torsion spring. This print head rotates the armature using a substantially uniform spring force and is capable of printing with high print quality.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing a conventional example, Fig. 2 is a partially cutaway perspective view of the print head, Fig. 3 is a schematic sectional view of the print head, Fig. 4 is a perspective view of the operating body, and Fig. 4 is a perspective view of the print head. 5 is an enlarged sectional view taken along the line A--A in FIG. 4, FIG. 6 is an explanatory view showing the state of attachment of brazing material, and FIG. 7 is an explanatory view showing a modified embodiment of the present invention. In the figure, 20 is a holder, 21 is an armature, 21
a is the opposite end, 22 is a torsion spring, 22a~
22c is a bulging portion, 23a and 23b are forked portions, 26
27a and 27b are chamfered portions, and 29 is a printing wire.

Claims (1)

[Claims for Utility Model Registration] In a print head for a dot printer, a rotary lever having a printing wire at its tip is rotatably supported by a holder via a torsion spring, and printing is performed at the tip of the printing wire, Holes are formed at opposite ends of the holder and the rotating lever, and the portions of the torsion spring that are inserted into the holes are made larger in diameter than the other portions, and A print head characterized in that the length in the central axis direction is not longer than the length in the same direction of the enlarged diameter part, and a brazing material is filled between each of the holes and the enlarged diameter part. .