JPH0440929Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a coil bobbin for an electromagnet in a printing head for an impact dot printer.

(Prior Art) The print head for an impact dot printer to which the present invention is directed has a circular yoke 1 as shown in FIG. , the tip of which stands up inside the yoke 1 as the core 2 of the electromagnet, and is arranged in a ring shape. Although not shown, a plurality of wires are arranged at the center, and each armature connected to each wire is arranged close to the upper part of the core 2 constituting an electromagnet.

A coil 4 wound around a bobbin 3 is attached to each core 2, and constitutes an electromagnet. Core 2 is
Due to the annular arrangement, the cross-sectional shape is approximately trapezoidal. FIG. 2 shows a conventional bobbin 3, and figure a shows a cross section of figure b. As is clear from FIG. 2, the conventional bobbin 3 has a uniform wall thickness and is formed thick.

(Problem to be solved by the invention) However, if the thickness of the bobbin is increased in order to form the bobbin well, the outer diameter of the print head becomes larger, which increases the burden on the motor in controlling the lateral feed of the print head. A problem arises in that the printer body becomes larger. Furthermore, when considering the heat generation of the coil, increasing the wall thickness is quite disadvantageous in terms of heat dissipation, and also raises the problem of increasing the cost by increasing the dielectric strength of the coil.

Therefore, if you try to reduce the outer diameter of the head,
The position of core 2 is also reflected toward the center, and the distance between adjacent cores is also narrowed. Therefore, the coil bobbin 3 installed
It is also necessary to reduce the wall thickness. When molding thin resin parts, the unevenness of the surface of the molded part of the mold generally poses a problem. In order to improve the flow of resin, the surface of the molded part of the mold is polished to reduce irregularities, but when the molded part is removed from the mold after molding, the thin part sticks to the surface of the mold and is easily torn. Furthermore, there is also the problem that air gets in the way during resin injection, making it difficult for the resin to flow. Even if thin-walled molding is possible using a material with good resin flow, sufficient strength may not be obtained, and when winding the coil around the bobbin, the outer shape of the coil may vary depending on how the winding force is applied. There is a problem that the inner shape may swell or conversely become narrow.

The present invention solves the above-mentioned problems of the conventional technology, and has good resin flow when forming the bobbin, has high mechanical strength as a coil bobbin, has excellent insulation and heat dissipation properties, and can be made smaller. The present invention provides a bobbin for a printing head that is capable of printing.

(Means for Solving the Problems) The bobbin of the present invention is constructed such that the wall thickness of the side surface facing the adjacent electromagnets becomes gradually thinner from the outer peripheral surface of the head toward the center.

(Function) According to the above configuration, during bobbin molding, the resin flows from the thick part to the thin part to facilitate the flow of the resin, and since it has the thin part, the heat dissipation effect is large and the wall thickness The structure ensures mechanical strength and sufficient insulation depending on the part.

(Example) Hereinafter, an example will be described in detail with reference to the drawings. FIG. 1 shows an embodiment of the present invention, in which a side surface 5a of a bobbin 5 facing an adjacent electromagnet,
The wall thickness of the head 5b is formed so that it becomes thinner as it goes from the outer circumferential side (portion A) to the center side (portion B) of the head.

With this configuration, when forming the bobbin,
By flowing the resin from the thick part A to the thin part B, the resin flows around very smoothly, and the bobbin can be formed well. Further, since the bobbin has the thick wall portion A, it has sufficient mechanical strength against the winding force when winding the coil around the bobbin, and the bobbin will not be deformed. Furthermore, regarding the heat generated by the coil, the thin-walled portion B of the bobbin has a greater heat dissipation effect than the conventional uniform and thick-walled portion, and can suppress the temperature rise.

(Effects of the invention) As explained above, according to the invention, the bobbin can be formed well, has sufficient mechanical strength, and has excellent heat dissipation and insulation properties. . Furthermore, since the printer can be made smaller, it is possible to reduce the burden on the motor in controlling the horizontal feed of the print head.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a block diagram of a conventional example, and FIG. 3 is a perspective view showing a yoke of a printing head and a coil attached to its core. 1... Yoke, 2... Core, 4... Coil, 5
...Bobbin, 5a, 5b...Side surface, A...Thick part, B...Thin part.

Claims (1)

[Scope of utility model registration request] A bobbin for a coil of the electromagnetic means in a printing head for an impact dot printer, in which a plurality of printing wires are arranged in the center, and electromagnetic means for individually driving the printing wires are arranged in a ring around the central part, A bobbin for a printing head, characterized in that the wall thickness of the side surface of the bobbin facing the adjacent electromagnetic means becomes thinner as it goes from the outer periphery to the center of the head.