JPH11147321A - Release type printing head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a pin from being broken by forming a recess for precluding the undesirable projection of a printing wire in a suction condition having foreign matter contained therein on at least one of the attraction surface of a yoke and armature. SOLUTION: A recess 32 is made on each magnetic attraction surface of yokes 4, 4 of a ferromagnetic body holding a permanent magnet therebetween for avoiding foreign matter. As such, if foreign matter 31 such as paper dust, metal dust, or the like cones in an interstice between the armature 9 and the yokes 9 during the printing period, foreign matter can be directed to the recess 32 formed on the magnetic attraction surfaces of the yokes 4, 4, so that foreign matter 31 never stays between the armature 9 and the yokes 4 during the non- printing period, and the armature 9 and yokes 4 are attracted closely, thus preventing the distal end of a wire pin 7 secured to the armature via an arm 8 from being kept in projection from a pin guide 14. In this manner, a problem can be solved in which the projected pin 7 catches an ink ribbon 15 with the consequence that the pin can be broken.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a print head of a printer, and more particularly, to a print head, in which foreign matter enters between a permanent magnet and an armature during printing, the armature cannot return to its original position, and is fixed to one end of the armature. The present invention relates to an improvement in a print head that prevents a printed wire from sticking out and being caught and damaged by an ink ribbon.

[0002]

2. Description of the Related Art FIG. 3 is a side view showing a main part of a conventional wire dot printer using a release type wire dot printer print head, and FIG. 2 is a diagram showing a magnetic suction drive unit provided with a magnetic circuit. 3 is a sectional view taken along line YY in FIG. 3, FIG. 4 is a view showing a driven part released by the magnetic circuit, and FIG. 5 is a perspective view for explaining a relationship between the driven part and a magnetic attraction driving part. .

In this conventional release type wire dot printer print head 1, a magnetic attraction driving unit A (drive) composed of a magnetic circuit is magnetically attracted by the magnetic attraction driving unit A against a spring force. And a driven portion B (driven) having a printing wire pin fixed to the armature. The magnetic attraction drive unit A sandwiches the permanent magnet 3 between the yokes 4 and 4 made of a ferromagnetic material.
A coil 6 that is wound around the bobbin 5 and that passes a current that generates magnetization that cancels the attraction of the permanent magnet 3 during printing is fitted and fixed (see FIG. 3).

On the other hand, in the driven portion B, as shown in FIG. 3, the base end of an arm 8 having a print wire pin 7 fixed to the distal end is fixed to the distal end of a ferromagnetic armature 9. The distal end portion 10a of the supporting spring plate 10 is fixed to the surface opposite to the magnetic attraction surface 9a of the above, and the base end portion 10b of the supporting spring plate 10 is supported by the supporting member 21.

[0005] Then, as shown in FIGS.
Driven parts B (one of them is shown in the figure)
The rear surface 21a of the support member 21 is
The wire dot printer print head 1 is completed. Although not shown, the magnetic attraction surface 9a of the armature 9 and the rear surface 21a of the support member 21 are provided at a certain angle. Specifically, the step at the lower end position of the armature 9 is about 37 microns, and the step at the upper end position is 128 microns.

During non-printing, the magnetic attraction surface 9a of the armature 9 to which the printing wire pin 7 is fixed is fixed by the permanent magnet 3 to the magnetic attraction surfaces 4a, 4a of the yokes 4, 4.
Is attracted against the elastic force of the supporting spring plate 10. At the time of printing, as shown in FIG. 4, an electric current is applied to the coil 6 to cancel the attractive force of the permanent magnet 3, and the elastic force of the supporting spring plate 10 causes the magnetic attraction of the armature 9 to which the printing wire pin 7 is fixed. The surface 9a separates from the magnetic attraction surfaces 4a, 4a of the yokes 4, 4 (opens at an angle of θ in FIG. 4), and the print wire pins 7 are moved to a predetermined position by the strain energy stored in the support spring plate 10 by elastic deformation. The paper is struck through the ink ribbon with a stroke.

In FIG. 3, reference numeral 14 denotes a pin guide,
Reference numeral 15 denotes an ink ribbon, 16 denotes paper, and 17 denotes a platen. As is well known, the operation of this release type wire dot printer is such that when printing is not performed, the magnetic attraction surface 9a of the armature 9 is made of a ferromagnetic yoke 4 with the permanent magnet 3 interposed therebetween.
4, the support spring plate 10 is elastically deformed and the strain energy is stored therein.
At the time of printing, when a current I is applied to the coil 6 by applying a pulse P having a pulse width Tp (not shown) to the coil 6 so as to cancel the attraction force of the permanent magnet 3 by a printing command from a printing control circuit (not shown). The magnetism generated by the armature 9 cancels the magnetic attraction force of the armature 9 fixed to the upper end of the support spring plate 10, and the armature 9 is restored by the restoring force of the strain energy stored in the support spring plate 10.
The tip of the printing wire pin 7 fixed via the arm 8 is displaced, and the tip of the printing wire pin 7 is guided by the pin guide 14 with the printing force Fp, and the paper 16 is applied to the platen 17 via the ink ribbon 15. And hit paper 16
Is printed.

Thereafter, the magnetic attraction surface 9a of the armature 9 is brought into contact with the magnetic attraction surfaces 4a, 4a of the ferromagnetic yokes 4, 4 sandwiching the permanent magnet 3 by the impact reaction force and the attraction force of the permanent magnet 3. Magnetically attracted.

[0009]

In the above-mentioned conventional release type wire dot printer print head, as shown in FIG.
Magnetic attraction surface 9 of armature 9
a between the magnetic attraction surfaces 4a, 4a of the yokes 4, 4
Gap appears. If foreign matter 31 of paper powder or metal powder floating in the space enters the gap, the current of the coil 6 is cut off during non-printing, and the armature 9 is magnetically attracted to the yoke 4 by the attractive force of the permanent magnet 3. Even if the foreign matter 31 becomes an obstacle, the magnetic attraction surface 9a of the armature 9 and the magnetic attraction surfaces 4a, 4a of the yokes 4, 4 cannot be in close contact with each other, so that the armature 9 does not return to the non-printing position. , Printing wire pin 7 fixed via arm 8
The pin 7 is left out of the pin guide 14, and the protruding pin 7 catches the ink ribbon 15, causing a problem of breakage of the pin.

[0010]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an apparatus according to a first aspect of the present invention provides an armature to which a printing wire is fixed as a magnetic path between a permanent magnet and a coil. At the time of printing operation, current is applied to the coil to cancel the magnetic flux of the permanent magnet, and the armature is moved toward the paper by its own elasticity. In the release-type print head that operates, at least one of the suction surface of the yoke and the armature is provided with a recess for preventing an undesired protrusion of the print wire in a suction state due to a foreign object being caught.

According to the above-described configuration, even if the floating foreign matter 31 fits into the minute gap between the armature 9 and the yoke 4 that appears during printing, the foreign matter 31 is inserted into the recess provided in the yoke 4 by the armature 9. Can be pushed in,
The magnetic attraction surface 9a of the armature 9 and the magnetic attraction surface 4a of the yoke 4 can be in close contact with each other, and the projection of the printing wire pin 7 can be prevented.

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a wire dot printer print head according to a first embodiment of the present invention; A is a magnetic attraction drive unit formed in the same manner as the conventional example,
The difference from the conventional example is that, as shown in FIG. 1, the magnetic attraction surfaces 4a, 4a of the ferromagnetic yokes 4, 4 sandwiching the permanent magnet 3 are provided.
The point is that a recess 32 for retracting foreign matter is provided in 4a.

A driven portion B is formed similarly to the conventional example. As described above, the coil 6 is used at the time of printing.
Current, the attractive force of the permanent magnet 3 is canceled, and the elastic force of the support spring plate 10 causes the printing wire pin 7 to move.
The magnetic attraction surface 9a of the armature 9 to which is fixed is separated from the magnetic attraction surfaces 4a, 4a of the yokes 4, 4 by an angle of θ, and even if the foreign matter 31 such as paper powder or metal powder enters the gap, the yoke 4, When foreign matter enters the depression 32 provided in the magnetic attraction surfaces 4a, 4a of the armature 4, the magnetic attraction surface 9a of the armature 9 and the yokes 4,
Of the magnetic attraction surfaces 4a, 4a.

Even when the foreign matter 31 adheres to the magnetic attraction surfaces 4a, 4a of the yokes 4, 4, when the driven portion is attracted to the magnetic attraction driving portion during non-printing, the magnetic force of the armature 9 is reduced. The foreign matter 31 can be stored so as to be pressed into the recess 32 by the attraction surface 9a, so that the foreign matter is not sandwiched between both magnetic attraction surfaces. In addition, as another embodiment of the depression 32, the magnetic attraction surfaces 4a of the yokes 4, 4 may be used.
If the corner of 4a is chamfered by about 0.5c, the metal foreign matter adhering to the chamfered edge portion may escape to the outside when the metal attracting surface 9a of the armature 9 is pressed. This makes it possible to prevent foreign matter from being caught in the suction surface.

As shown in FIG. 6, the magnetic attraction surfaces 4a,
The same effect can be obtained even if a depression is provided in a honeycomb shape in 4a. Also, as shown in FIG. 7, a similar effect can be obtained by providing a plurality of depressions in the shape of clogs on the magnetic attraction surfaces 4a, 4a. In addition,
In the description of the above embodiment, the case where the present invention is applied to a release type wire dot printer print head has been described.However, the present invention is not limited to this, and as another embodiment, a print wire pin is fixed at the time of printing. An armature is attracted to a permanent magnet, printing is performed by striking the paper with an ink ribbon using a printing wire pin, and a current is applied to the coil to cancel the magnetic force of the permanent magnet when printing is not performed. Needless to say, it can be applied to a head.

Further, in the description of the above embodiment, the depression is provided on the yoke, but may be provided on the magnetic attraction surface of the armature. Further, in the description of the above embodiment, the depression is provided on the magnetic attraction surface. However, a protrusion may be provided with the concavities and convexities reversed, and the apex or surface thereof may be used as the magnetic attraction surface.

[0017]

As described in detail above, according to the present invention,
Even when foreign matter 31 such as paper powder or metal powder enters the gap between the armature 9 and the yokes 4, 4 during printing, the foreign matter can escape to the recesses 32 provided in the magnetic attraction surfaces 4a, 4a of the yokes 4, 4, and The foreign matter 31 is not pinched between the armature 9 and the yoke 4 at the time of printing, the armature 9 and the yoke 4 can be in close contact with each other, and the tip of the printing wire pin 7 fixed to the armature 9 via the arm 8 can be used as a pin guide 14. You won't be left out of the box.

Accordingly, there is an effect that it is possible to prevent a problem that the protruding pin 7 catches the ink ribbon 15 and breaks the pin.

[Brief description of the drawings]

FIG. 1 is a side view showing a main part of a wire dot printer using a release type wire dot printer print head of the present invention.

FIG. 2 is a cross-sectional view taken along the line YY of FIGS. 1 and 3, showing a magnetic attraction drive unit having a magnetic circuit.

FIG. 3 is a side view showing a main part of a conventional wire dot printer using a release type wire dot printer print head, in which a magnetic suction drive unit is attracted to a driven part.

FIG. 4 is a side view showing a driven part released by a magnetic circuit.

FIG. 5 is a perspective view illustrating a relationship between a driven portion and a magnetic attraction driving portion of a conventional wire dot printer using a release type wire dot printer print head.

FIG. 6 is a perspective view showing another embodiment of the yoke magnetic attraction surface of the present invention.

FIG. 7 is a perspective view showing another embodiment of the yoke magnetic attraction surface of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Print head 2 Base 2a Support piece 2b Front surface 3 Permanent magnet 4 Yoke 4a Magnetic attraction surface 5 Bobbin 6 Coil 6a Coil terminal A Magnetic attraction drive unit 7 Print wire 8 Arm 8a Base end 9 Armature 9a Magnetic attraction surface 10 Support spring Part 10a Tip part 10b Base part B Driven part 14 Pin guide 15 Ink ribbon 16 Paper 17 Platen 21 Support member 21a Rear surface 22 Base 31 Foreign matter 32 Depression

Claims (1)

[Claims] An armature having a print wire fixed thereto is attracted to a yoke surface which is a magnetic path between a permanent magnet and a coil, and during a printing operation, an electric current is applied to the coil to cancel out the magnetic flux of the permanent magnet and thereby to reduce the armature. In the release type print head that performs a predetermined printing operation via a printing wire by moving the paper to the paper side with its own elasticity, at least one of the suction surface of the yoke and the armature is sucked by a foreign substance and sucked. A release type print head characterized by having a depression for preventing an undesired projection of a print wire.