JPH0235670B2 - WAIYAADOTSUTOPURINTAAYOINJIHETSUDO - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to wire dot printers, and more particularly to a print head for a wire dot printer having a wire driven by an electromagnet. [Prior Art] A wire dot printer attempts to express characters using a dot matrix by moving a printing head, usually equipped with one or two rows of wires, in a fixed direction at a predetermined pitch. . The printing head of such a wire dot printer normally drives a wire by the operation of an electromagnet, and the basic structure of the printing head is as shown in FIG. In FIG. 1, the printing head 1 has a frame formed by a yoke 3 and a back frame 4 with a front frame 2 as a reference, and an iron core 5 and a coil 6 wound around it are attached to the yoke 3. There is. armature 7
has one end connected to a part of the yoke 3,
The free end is rotatable. wire 8
is guided by guide plates 9 to 11, is directly connected to the free end of the armature 7, and is configured to be returned by a spring 12 mounted between the free end of the armature 7 and the guide plate.
Further, a plate spring 13 is fixed to the back frame 4 for the purpose of stabilizing the operation of the armature 7. The printing head is usually constructed of a plurality of wires, and in this case, electromagnets of the same number as the number of wires are formed concentrically within the yoke 3. The tip of the wire 8 moves back and forth in accordance with the movement of the armature 7, and printing is performed on the paper 17 via the ink ribbon 14. The armature 7 has a corresponding electromagnetic coil 6
By applying a pulse signal to yoke 3,
It operates intermittently and at high speed between the adsorption surface of the side surface and iron core 5 and the surface of the plate spring 13 on the armature 7 side. In the prior art, intermittent high-speed operation of the armature 7 causes wear, deformation, and deterioration between contact surfaces, resulting in deterioration in printing quality and shortening of service life. Therefore, a method of intervening a non-magnetic metal spacer such as phosphor bronze between the armature 7 and the side surface of the yoke 3 and the adsorption surface of the iron core 5 was considered, but this method does not work because of the residual magnetism of the iron core 5. However, since the metal spacer is malleable, the above-mentioned intermittent high-speed operation of the armature 7 causes it to bend and deform during long-term use, causing the iron core 5 to There was a drawback that the clearance of the armature 7 became unstable and the printing quality was extremely degraded. Also, as seen in the content of Japanese Patent Application Laid-Open No. 57-126671, a synthetic resin film is interposed between the armature 7 and the plate spring 13 and between the armature 7 and the side surface of the yoke 3 to prevent wear and reduce wear. Although devised to suppress sound, the polyester film mentioned in the example does not have very good abrasion resistance, requiring maintenance to replace the film, and also lacks heat resistance. Divided. That is, due to the generation of sliding friction heat and striking friction heat caused by intermittent high-speed operation of the armature,
Problems such as film deformation and stickiness may occur.
As a result, the wear progresses and the original purpose cannot be achieved. Furthermore, in the technique disclosed in this publication, since no film is interposed between the armature and the iron core, it is impossible to prevent wear and noise occurring between these members. [Object of the Invention] As a result of research to solve the above-mentioned problems of wear, heat resistance, and noise that could not be obtained with the prior art, the present invention has been developed to improve printing quality by using a plastic film spacer with a specified composition. To provide a printing head for a wire dot printer which is superior in terms of durability and durability. [Structure of the Invention] The present invention relates to a wire dot printer that drives a wire by the operation of an electromagnet to perform printing. This is a printing head for a wire dot printer, characterized in that a polyetheretherketone film is interposed between the print head and the print head. FIG. 2 is for explaining an embodiment of the present invention, and the explanation of the same parts as in FIG. 1 will be omitted. armature 7
A polyetheretherketone film 16 is interposed between the side surface of the yoke 3 and the adsorption surface of the iron core 5. Further, a polyetheretherketone film 15 is also interposed between the armature 7 and the plate spring 13. In this case, the films 15 and 16 may be adhered to the plate spring side and the yoke side surface, respectively, using an adhesive. By the way, the polyetheretherketone used is a crystalline thermoplastic plastic with a glass transition point of 130°C or higher and a melting point of
It is a light brown plastic with a temperature of 300°C or higher, and can be obtained by melt extrusion, solution casting, etc. If necessary, it can also be made into a stretched film by post-stretching. The thickness of the polyetheretherketone film used is usually 10 to 200μ, and it has
Various selections are made depending on magnetic force, etc. By the way, the second
Although the illustrated embodiment is an example of a clapper type print head, the present invention is also applicable to a spring charge type print head as shown in FIG. The spring charge type printing head 18 has a skeleton formed by a first yoke 19, a second yoke 20, and an armature holder 21.
A permanent magnet 23 is provided in between, and an electromagnet is constituted by an iron core 24 formed integrally with the first yoke 19 and a coil 25 wound around it. The armature 26 has a plate spring 27 attached to one end.
This plate spring 27 is fixed between the armature holder 21 and the spacer 28 with screws 29, and these assemblies are fixed to the second yoke 20. Further, a wire 31 guided by a wire guide 30 is attached to the other end of the armature 26. In the non-printing state, the armature 26 is attracted and held on the iron core 24 by the permanent magnet 23 while the plate spring 27 is bent. When a pulse signal is applied to the coil 25, the magnetic field generated by the electromagnet cancels the magnetic field of the permanent magnet 23, the armature 26 is released from the attracted and held state, and the wire 31 is driven to perform a printing operation. In this type of print head, the armature 26
However, when returning from the release state to the adsorption state, the iron core 2
Because it violently collides with the suction surface of No. 4, the suction surface is worn out and noise is generated. As a result, the amount of deflection of the plate spring increases, and the printing force becomes excessive, making it impossible to perform a proper printing operation. Therefore, in this embodiment, as shown in FIG.
Between the armature 26 and the suction surface of the iron core 24,
A polyetheretherketone film 32 is interposed therebetween. In this case, the parts to which mechanical contact stress is applied are the armature 26 and the iron core 2.
4, it is sufficient to interpose the film 32 only in this portion. In addition, in this type of print head, the armature 26 is normally held by suction on the iron core 24, and the first yoke 19, the second yoke 20, and the spacer 28
Since the annular outer wall portion 22 is formed, there is no need to bond the film 32 with adhesive. Incidentally, the shape of the film 32 is shown in FIG. [Effects of the Invention] According to the present invention, the abrasion resistance that occurs when using a non-magnetic metal spacer as described above or a general synthetic resin film such as polyester as shown in Japanese Patent Application Laid-open No. 57-126671 as a spacer can be improved. This makes it possible to suppress deterioration in print quality and lifespan caused by problems in terms of hardness and heat resistance. Furthermore, in the present invention, since the film is soft and is interposed between the armature and the iron core, unpleasant metallic sounds are alleviated and the soundproofing effect is further improved. Furthermore, it has been found that the present invention can be applied not only to print heads for dot printers, but also to areas where wear occurs due to intermittent high-speed movement caused by the operation of electromagnets, etc., to obtain very large effects. [Example] Table 1 lists Examples and Comparative Examples. In both cases, in the embodiment shown in Fig. 2, the state after operation up to 50 million times is shown when a plastic film is interposed between the armature and the yoke side surface and the suction surface of the iron core, and between the armature and the plate spring. Examined. As can be seen in the table, polyetheretherketone is crystalline like polyester, and has the highest melting point except for Kapton film, which is a thermosetting resin. Although polysulfone and polyethersulfone have a higher glass transition point than polyetheretherketone, their performance is inferior because they are amorphous and become sticky due to the frictional heat generated. This is because the abrasion properties are extremely reduced. Because polyester film has a low glass transition point, the heat generated by friction reaches temperatures of 120 to 140°C on the surface of the film, causing the film itself to shrink and peel off from the adhesive surface. Kapton film is significantly inferior to plastic film in terms of abrasion resistance. 【table】

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventional print head for a wire dot printer, FIG. 2 is a sectional view of a print head for a wire dot printer according to the present invention, and FIG. 3 is a sectional view showing another embodiment of the present invention. FIG. 4 is a plan view showing the shape of the film of the present invention. 1, 18; Print head, 3; Yoke, 5, 2
4; iron core, 6, 25; coil, 7, 26; armature, 8, 31; wire, 13, 27; plate spring, 15, 16, 32; polyether ether ketone film.

Claims (1)

[Claims] 1. In a wire dot printer that prints by driving a wire through the operation of an electromagnet, there is a
A printing head for a wire dot printer, characterized in that a polyetheretherketone film is interposed between members that repeatedly generate mechanical contact stress and heat generation.