JPH047973Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a wire dot print head for use in a printer.

(Prior technology) Among the conventional wire dot printing heads, the
As shown in No. 58-35474, there is a device that uses a wear-resistant resin film as a so-called residual sheet between the armature and the core, but since this wear-resistant resin film is a non-magnetic material, it cannot be used with permanent magnets. There was a problem that the suction power of the armature was reduced due to this.

For this reason, it has been considered to use a thin metal plate made of ferromagnetic material instead of this wear-resistant resin film.

(Problem to be solved by the invention) However, as mentioned above, when a thin metal plate of ferromagnetic material is used, this thin metal plate and the armature or core are of the same type of metal, so adhesive wear (fusion) due to the same type of metals. (including wear and tear) increases,
A problem arises in that the thin metal plate, armature, or core are prone to wear, which shortens the life of the wire dot print head. In order to extend the life of the wire dot printing head, a thin plate made of abrasion resistant resin is used as the residual sheet instead of a thin metal plate, and wear from the core side of this resistant resin resin sheet is reduced. Therefore, it has been considered to lubricate the space between the core and the core using silicone grease or the like.

However, in the manufacturing process of wire dot printing heads, it is difficult to avoid the adhesion of fine dust, magnetic powder, etc., and if excessive stress is applied to a part of the residual sheet due to these dusts, the resin-made sheet will become stressed. The lubricant leaks from this part to the armature side because it is vulnerable to damage, and this can cause the armature and the residual sheet to stick together, resulting in a dot drop phenomenon.
In the end, attempts to extend the life of the wire dot printing head by applying silicone grease to the resin residual sheet were difficult to ensure reliability.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention uses a ferromagnetic material for the residual sheet, and also uses a plastic material with a low coefficient of friction between the residual sheet and the armature. formed a layer.

(Function) According to the present invention, most of the thickness of the residial sheet is made of ferromagnetic material, so even if it is inserted between the armature and the core, the magnetic properties are almost the same as when it is not inserted. do not have. Furthermore, since a plastic layer with a low coefficient of friction is formed between the residial sheet and the armature, adhesive wear due to similar metals does not occur.

(Embodiment) FIG. 1 is a half-sectional view showing an embodiment of the present invention, in which 1 is a first yoke, 2 is a core having a notch at a corner, 3 is a coil fitted into the core 2, and 4 is a half-sectional view showing an embodiment of the present invention. is core 2
It is a core piece that is attached to the notch of the core, and is made of a resin with good wear resistance and heat resistance, such as polyamideimide or polyetheretherketone.
5 is a permanent magnet, 6 is a second yoke, 7 is a third yoke, 8 is a ferromagnetic residial sheet made of a thin metal plate made of ferromagnetic material and coated with a resin having a low coefficient of friction on the surface 8a, 9 is a leaf spring, 10 is armature,
11 is a printing head, 12 is a fourth yoke, 13 is a fifth yoke, 14 is a vibration damping guide that limits the horizontal vibration of the printing wire 11, 15 is a tip guide, 16 is a head frame, and 17 is a reciprocal sheet 8 and a core. 2
This is the grease applied in between. The embodiment operates as follows.

First, in a state where the coil 3 is not energized, the magnetic flux of the permanent magnet 5 is
Passes through yoke 6. At this time, since a magnetic attraction force is generated between the core 2 and the armature 10, the leaf spring 9 is loosely deformed into an S-shape. When the coil 3 is energized in this state, the magnetic flux of the coil 3 is transferred to the armature 1.
The armature 10 is released from the core 2 in order to cancel the magnetic flux of the permanent magnet 5 in the gap between the permanent magnet 5 and the core 2. Therefore, as the armature 10 is attracted to the core 2, the strain energy accumulated in the leaf spring 9 is released, and the armature 10 fixed to one end of the leaf spring 9 is moved to the core piece 4 provided at the corner of the core 2. Rotate clockwise around the corner of the
By this rotational movement, printing is performed using the printing wire 11 fixed to the armature 10.

Furthermore, in this embodiment, core 2 and armature 1
In order to prevent wear and tear on the opposing surfaces 2a and 10a of the core 2 and to prevent wear of the ferromagnetic residial sheet 8, thereby extending the service life of the core 2, the opposing surfaces 2a and 10a of the core 2 are
A and the ferromagnetic residial sheet 8 are lubricated with silicone grease 17, and the armature 1
The surface 8a of the ferromagnetic residial sheet facing the opposing surface 10a of the ferromagnetic sheet is coated with a plastic coating made of a material with a low coefficient of friction such as Teflon.

This plastic coating is made by Acheson's Emlaron, which is mixed with a solid lubricant such as carbon.
If 333 is used, the friction with the armature 10 will be further reduced, resulting in even less wear. The thickness of this plastic coating is 5 to 10 .mu.m, which is sufficient for prolonging the life of the wire dot printing head, and in this embodiment, the thickness was 10 .mu.m.

As a result, the lifespan of the proposed wire dot printing head (for example, the lifespan is defined as the time when the residial sheet wears out, the printing operation characteristics deteriorate, and dot removal occurs) is longer than that of the conventional wear-resistant resin head. The lifespan is approximately twice that of a wire dot printing head using a residial sheet (thickness 50μ3).

The reason for this is that while conventional residial sheets made of wear-resistant resin wear progresses from both the core side and the armature side, the ferromagnetic residial sheet of this invention significantly reduces the wear progress from the core side. It was found that wear hardly progressed when grease lubrication was applied, and because the armature surface side was coated with plastic made of a low friction coefficient material such as Teflon, adhesive wear due to friction with the armature could be prevented, and wear was significantly reduced.

Also, the working gap between the core and armature is different from the conventional one.
Compared to 50 μm, this can be reduced to 1/5 of 10 μm, which makes it possible to reduce the magnetic force of the permanent magnet 5 and reduce the magnetic resistance of the working gap, which not only makes it possible to reduce the drive current of the armature, but also to reduce the permanent magnet 5. The size of the magnet 5 can be reduced, and a wire dot printing head with low power consumption and long life can be provided at low cost.

FIG. 2 is a graph showing the attractive force characteristics of the permanent magnet 5 used in this example, and FIG. 3 is a graph showing the attractive force of the permanent magnet 5 and the armature drive current (peak value) when the printing force is constant. It is a graph showing the relationship between However, the permanent magnet is used in an unsaturated state.

Now, in order to reduce the power consumption of the wire dot printing head, it is necessary to make the working gap between the armature and the core as small as possible, but in this example, the working gap is 1/5 of the conventional one, and the armature is driven. Since the current is small, power consumption is low.

Furthermore, although the thickness of the ferromagnetic residual sheet 8 in this embodiment was set to 50 μm, the thickness may be changed to 100 μm or more.
Even if the thickness was changed to 500 μm, the effect was almost the same.

The degree of magnetic interference when the residual sheet is made of a ferromagnetic material is about the same as that of the conventional one as far as experiments were conducted with a sheet thickness of 150 μm, and it can be said that there is no effect of using a magnetic material as the residual sheet.

Furthermore, although the coating thickness of Emlaron 333 in this case was set to 10 μm, the same effect could be obtained by increasing the coating thickness to 5 μm each and coating the opposing surfaces of the ferromagnetic residial sheet and the armature. The effect of preventing rust can be obtained.

Further, in the above embodiment, the surface 8a of the magnetic residial sheet 8 is coated with plastic, but instead of this coating, a plastic film with high mechanical strength and wear resistance such as polyester film is used as shown in FIG. 18 may be inserted. Furthermore, this plastic film 18
Since it is thin and weak, it is better to strengthen the outer periphery by making it thicker.

Also, in this embodiment, the surface 10 of the armature 10
A plastic coating 19 made of a material with a low friction coefficient such as Teflon is applied to a. As described above, if Emlaron 333 manufactured by Acheson Co., Ltd. mixed with a solid lubricant such as carbon is used as the plastic coating 19, the friction with the plastic film 18 will be further reduced and the effect will be further increased. The thickness of the plastic coating 19 is 4 to 10 .mu.m, which is sufficient for extending the life of the wire dot printing head, and in this embodiment, the thickness is 4 .mu.m, and the thickness of the plastic film 18 is 6 .mu.m.
As a result, the lifespan was approximately 2.5 times longer than that of a wire dot print head using a conventional plastic reciprocal sheet (thickness 50 μm).

The reason for this is that while conventional residial sheets made of wear-resistant resin develop wear from both the core side and the armature side, the ferromagnetic residial sheet of this invention significantly reduces the wear progress from the core side. Furthermore, since grease lubrication was applied, wear hardly progressed.

Furthermore, it was found that because the facing surface of the armature was coated with plastic made of a material with a low coefficient of friction such as Teflon, the friction between the plastic film inserted between the armature and the ferromagnetic reciprocal sheet was reduced, and wear was reduced. .

(Effect of the invention) As explained above, according to the invention, even if there is a reciprocal sheet, it is magnetically the same as not having one, so the suction characteristics of the armature do not deteriorate, and the Since a plastic layer with a low coefficient of friction is formed between the metal part and the armature, adhesive wear due to similar metals does not occur, which has the effect of extending the life.

Furthermore, in the present invention, lubrication between the residual sheet and the armature is achieved by a plastic layer with a low coefficient of friction formed on the residual sheet, making the formation of this lubrication layer extremely easy and the process inexpensive. can be done.

Furthermore, since the residual sheet of the present invention is formed primarily from a ferromagnetic material, that is, a thin metal plate, it is less likely to break due to local stress caused by dust or the like.

[Brief explanation of the drawing]

Fig. 1 is a half-sectional view showing an embodiment of the present invention, Fig. 2 is a graph showing the attractive force characteristics of the permanent magnet used in this embodiment, and Fig. 3 shows the permanent magnet when the printing force is constant. FIG. 4 is a graph showing the relationship between the attraction force and the drive current (peak value) of the armature, and FIG. 4 is an enlarged half-sectional view of the main part showing another embodiment of the present invention. 1...First yoke, 2...Core, 3...Coil, 4...Core piece, 5...Permanent magnet, 6...
2nd yoke, 7...Third yoke, 8...Ferromagnetic residial sheet, 9...Leaf spring, 10...Armature, 11...Printing wire, 12...Fourth yoke, 13...Fifth yoke , 14... vibration damping guide,
15...Tip guide, 16...Head frame,
17...Grease, 18...Plastic film, 19...Plastic film.

Claims (1)

[Claim for Utility Model Registration] An armature with a printing wire fixed to its end is fixed to the free end side of a leaf spring, and the magnetic force of a permanent magnet is used to move the armature against the elastic force of the leaf spring to create a reciprocal sheet. A spring charge type in which the magnetic force of the permanent magnet is canceled out by excitation of a coil arranged in the core, and the armature is released from the core by the elastic force of the leaf spring to drive the printing wire. In the wire dot printing head, the residual sheet is made of a ferromagnetic material, and a plastic layer with a low coefficient of friction of 10 μm or less is formed on the surface of the registrar sheet facing the armature. A wire dot printing head characterized by having a grease layer formed on the opposite side to the plastic layer.