JPS5942967A - Printing head - Google Patents

Abstract

PURPOSE:To attain the high-density mounting and speed-up of a printing head as well as improve the radiation of heat generated in coils by a method in which the cross section of a core to be wound with a coil is shaped such that the coil can be smoothly wound. CONSTITUTION:An armature 2 is attracted by a core 5a by means of the attraction force of a permanent magnet 6, and a plate spring 4 is flexed to generate a recovery force. A screw 9 is turned and the spring force of the plate spring 4 is adjusted. An electric current is flowed in a coil 7 and the magnetic flux of the magnet 6 is erased, whereupon the armature 2 is turned at the point A as a supporting point, and an ink ribbon and a printing paper are struck by the tip of the dot wire 1 to prent lettes. When the coil 7 is wound around the core 5a, no abrupt bending force acts on the coil 7 because the tip of the core 5a is rounded off. Therefore, the insulating film of the coil 7 is not broken. The heat generated in the coil 7 is easily conducted to the core 5a, and thereby the radiation of the heat of the coil 7 is improved and the efficiency of the electromagnet is also raised.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a print head for an impact type printer, and more particularly to a print head in which a core that applies magnetic attraction force to an armature and a coil wound around the core are arranged in the circumferential direction.

Some print heads of impact printers have a core and a coil wound around the core arranged in the circumferential direction. In recent years, in this type of print head, in order to obtain high print quality, the number of dot wires has increased and high-density packaging is required. On the other hand, due to the increase in the number of dot wires,
As the number of coils installed increases as well, more heat tends to be generated than in conventional systems.

Due to the above-mentioned high-density packaging, the cross-sectional shape of the cores arranged in the circumferential direction generally has a trapezoidal cross-section. Since it is difficult to wind a coil around a core having such a trapezoidal cross section with uniform gaps, a gap is created between the core and the coil near the center of each side of the trapezoidal cross section. A solution to this problem is to increase the tension when winding the coil around the core, thereby reducing the above-mentioned gap. However, since the coil is suddenly bent at the four vertices of the trapezoidal cross section of the core, the insulating film layer of the coil will be destroyed. For this reason, the current situation is that the formation of non-uniform and large gaps between the core and the coil cannot be removed. Therefore, this gap creates a very large thermal resistance in the heat radiation path, and the heat radiation described above is not sufficient, which is an obstacle to increasing the density of the print head and increasing the speed of printing.

The present invention has been made based on the above-mentioned matters, and an object of the present invention is to provide a print head that can achieve high density and high speed.

The feature of the present invention is that the cross-section of the core around which the coil is wound is configured in a shape that allows the coil to be wound smoothly, which improves heat dissipation generated by the coil and enables high-density packaging. It is something.

An embodiment of the print head of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the print head of the present invention.
In the figure, 1 is a dot wire, 2 is an armature, and 3 is a lever provided with the dot wire 1, which is attached to the armature 3. 4 is a leaf spring provided in the armature 2, 5a and 5bij cores, 6 is a permanent magnet provided between the cores 5a and 5b, 7 is a coil installed in a part of the core 5a, 8
a is Herad pace, 8b is head cover, 9 is leaf spring 4
1o is a guide for guiding the dot wire 1, and 11 is a holder for the guide 10. The aforementioned dot wire 1. Armature 2. A movable section consisting of a lever 3 and a leaf spring 4, and a magnetic force generating section consisting of cores 5a, 5b, permanent magnets 6, coils 7, etc. that drive this movable section constitute a unit, and are arranged in the circumferential direction of the head. be done.

The core 5a has a magnetic pole face M'f facing the armature 2.
The cross-sectional shape of the part around which the coil 7 is wound has an approximately trapezoidal basic cross-section as shown in FIG. The sides are shaped like a gentle curved line that is convex to the outside.

Next, the operation of one embodiment of the print head of the present invention described above will be explained.

Before printing starts, the armature 2 is attracted to the core 5a by the attractive force of the permanent magnet 6.

At this time, the leaf spring 4 is bent and generates a restoring force. Here, by rotating the screw 9, the spring force of the leaf spring 4 can be freely adjusted. Next, when a current is applied to the coil 7 to completely cancel the magnetic flux of the permanent magnet 6, the armature 2
rotates around point A as a fulcrum. As a result, the tip of the dot wire 1 hits the ink ribbon or printing paper to print desired characters on the printing paper.

Further, according to the present invention, when the coil 7 is wound around the core 5aK, the apex of the core 5a is rounded, so that no sudden bending force is applied to the coil 7 at this apex. For this reason,
The insulation film of the coil 7 is not damaged. Further, the coil 7 has the above-mentioned cross-sectional shape of the core 5a.
core 5a with a uniform and very small gap between
Since the coil 7 can be installed in the core 5a, the heat generated in the coil 7 is easily transmitted to the core 5a, and the heat radiation of the coil 7 is improved. moreover,
Since the cross-sectional area of the core 5a can be made larger than before,
The efficiency of the electromagnet is also improved.

Note that although the above-described embodiments have been described with respect to a printer equipped with a permanent magnet, the present invention can also be applied to printers other than this. Furthermore, although the basic cross-sectional shape of the core 5a is trapezoidal, it is also applicable to rectangular, square, pentagonal, and other polygonal shapes.

As described in detail above, according to the present invention, the gap between the coil and the core can be reduced, making it easier to dissipate the heat generated in the coil, making it possible to implement high-density packaging and increase speed. .

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional side view showing an embodiment of the print head of the present invention, and FIG. 2 is a sectional view taken along the line II--II in FIG. 1... Dot wire, 2... Armature, 3...
・Reno (-14... leaf spring, 5a, 5b... core,
6...Permanent magnet, 7...Coil.

Claims (1)

[Claims] 1. A print head comprising a core having a magnetic pole surface that applies a magnetic attraction force to an armature, and a coil wound around the core to control the magnetic attraction force, in which the coil is wound. The main feature of this print head is that the core to which it is attached has a cross-section that allows the coil to be wound smoothly. 2. The basic cross-sectional shape of the core is a polygon.
The print head according to claim 1, characterized in that the top portion thereof is formed into a curved surface. 3. The cross-sectional shape of the core is based on a polygonal cross-section.
2. The print head according to claim 1, wherein the top and sides of the print head are formed with outwardly convex curved surfaces. 4. The print head according to claim 2 or 3, wherein the basic cross-sectional polygon is a trapezoid.