JPS6048372A - Printing head - Google Patents

Abstract

PURPOSE:To reduce the weight of an armature lever without losing strength and rigidity, by winding the armature lever in the vicinity of a position where max. stress is generated, and narrowing the width of the other part so as to make stress during printing smaller than max. stress. CONSTITUTION:Stress (solid line) generated in an armature lever 1 when printing force F is acted on the leading end of a printing wire 3 is made smaller than the max. tolerant stress (broken line) of the armature lever 1. The width of the armature lever 1 is made widest at a position 1A which is the securing part with the armture 5 and remotest from a rotary fulcrum 5A and the other part thereof is made gradually narrow to prevent the lowering in strength when the thickness of the armature lever 1 is made thin.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a wire dot matrix print head, and particularly to a wire dot matrix print head suitable for high-speed printing.

[Background of the invention]

FIG. 1 shows a schematic diagram of a wire dot matrix print head.

The printing wire 3 is individually attached to the tip of the armature lever 1, and the rear end of the armature lever 1 is individually attached to the armature 5. A leaf spring 2 is attached to the armature 5, and the leaf spring 2 is biased by a pressing means 4, giving a force to the armature 5 to rotate in the direction of arrow A. The drive mechanism of the armature 5 is constituted by a magnetic circuit including a permanent magnet 6, a yoke portion 7, a core portion 71 that is a part of the yoke portion 7, a coil 8, and the like.

When not printing, the armature 5 is attracted to the permanent magnet 6. During printing, the armature 5 is released from the permanent magnet 6 by energizing the coil 8 to cancel the magnetic flux of the permanent magnet 6. The released armature 5 rotates in the direction of arrow A due to the elastic force of the leaf spring 2 and drives the printing wire 3.
The tip of the printing wire 3 impacts the printing medium 10 on the platen It via the ink ribbon 9 to perform printing on the rollers 1 to 1.

In printers, printing speed is a major factor that determines product value. In order to perform high-speed printing, the driving cycle of the printing wire 3 must be made faster.

For this purpose, it is necessary to reduce the mass of the armature assembly, which is a moving part. Therefore, instead of extending the armature 5 and attaching the printing wire 3 directly to the armature 5, the armature lever 1 is made of a lightweight material such as stainless steel except for the part that is attracted to and comes into contact with the permanent magnet 6. The printing wire 3 is attached to 1. Furthermore, in order to reduce weight, the fixed portion between the armature 5 and the armature lever l is formed into a sloped shape.

However, especially in the case of complex characters such as Chinese characters, the printing time per character is long, so in order to increase the total printing speed of the entire document, it is necessary to further increase the driving cycle of the printing wire 3. To achieve this, it is necessary to thoroughly reduce the mass of the armature assembly. One possible method for this is to reduce the plate thickness of the armature lever 1, but when the plate thickness is reduced, there is a problem that the strength and rigidity are reduced.

[Purpose of the invention]

An object of the present invention is to reduce the weight of the armature assembly of a wire dot matrix print head without sacrificing strength or rigidity, and to provide a print head that enables high-speed printing, in order to solve the problems of the prior art as described above. It is about providing.

[Summary of the invention]

In order to achieve the above object, the present invention provides an armature and an armature lever that are fixed to each other using a slope that reduces the plate thickness in the length direction as a fixed part, a driving means for driving the armature, and a print fixed to the armature lever. In the dot marix printing head, which includes a plurality of wires and prints characters, figures, etc. by selectively driving the driving means and impacting the printing medium with the tips of the printing wires, the plate of the armature lever The width of the armature lever, which has a reduced plate thickness, is gradually widened from the side to which the printing wire is fixed to the fixed part, and the width of the armature lever is made to be lighter by reducing the thickness. It is characterized by having a maximum width near the beginning of the slope and gradually narrowing toward the end of the slope to prevent a decrease in strength and rigidity due to thinning of the plate.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described based on the drawings.

In order to reduce the weight of the armature assembly, it is possible to reduce the thickness of the armature 5 and armature lever 1, but since the armature 5 needs to be attracted to the permanent magnet 6 when not printing, the thickness of the armature 5 and armature lever 1 can be reduced. It cannot be made thinner. Therefore, it is necessary to reduce the thickness of the armature lever l to reduce its weight. When the plate thickness is reduced, the problem is that the strength and rigidity are reduced. Namely.

As the plate thickness becomes thinner, the strength decreases, which may cause breakage, and even though the rigidity is reduced, the contact time with the printing medium becomes longer, and the printing wire 3 may catch the ink ribbon 9, or the printing wire 3 may catch the ink ribbon 9. When it hits the printing medium 1o, the repulsion becomes worse, and the printing operation becomes slower.

If we try to prevent the decrease in strength and rigidity caused by reducing the thickness of the armature lever 1 by widening the width of the armature lever l, as shown by the broken line in Fig. 2, the mass of the armature 5 will be reduced in the shaded area. It gets bigger and heavier. Therefore, as shown in FIG. 3, it is conceivable to increase the width of the armature lever 1 while leaving the width of the armature 5 unchanged. However, in this case, the armature becomes higher than the armature 5 by the dimension a at the maximum width of the armature/<-1. Therefore, the members located closer to the print medium IO than the armature assembly must be shifted toward the print medium 10 by a space of dimension a, and the print head becomes longer. For this reason, printing wire 3
becomes heavier by the length of dimension a, and the effect of reducing the weight of the armature assembly as a whole becomes smaller.

Therefore, it is necessary to widen the width of the armature lever (■) in a way that maximizes the effect of weight reduction.

In the armature assembly in which the plate thickness of the armature lever 1 shown in FIG. As shown by the solid line in b), the maximum stress is at the fixed part with the armature 5,
Moreover, it occurs at the farthest position IA from the rotation fulcrum 5A of the armature 5.

This maximum stress must be made smaller than the maximum allowable stress of the armature lever 1, as shown by the broken line in FIG. 4(b). Therefore, in order to achieve the bending stress shown by the broken line in FIG. 4(b), the width of the armature lever 1 is adjusted as shown in FIG.
By making the position IA farthest from A the widest part and gradually tapering the other parts, it is possible to prevent a decrease in strength even if the plate thickness of the armature lever 1 is made thinner.

The effects of weight reduction in this case are as follows. Consider a case where the plate thickness of armature lever 1 is increased by 1/n times. 1 of armature lever 1. If the width of part A is W and its thickness is t, the maximum stress is proportional to 1/'tW2, so if the thickness t of armature lever 1 is increased by 1/n times, the fixed part with armature 5 will be If the width W of the tip IA portion is made ψ100 times the original width, an armature lever 1 having the same strength as the plate thickness t can be obtained. At this time, since the change in the mass of the armature lever 1 is approximately proportional to tx (Wh), the plate thickness t of the armature lever 1 is set to 1.
/ n times the width W of the tip IA part of the fixed part with the armature 5 is multiplied by i, the armature lever 1 is
The weight can be reduced in proportion to the TV X h.

Also, when comparing the example shown in Fig. 4(C) and the example shown in Fig. 3, the mass of Fig. 4(C) is lower due to the deletion of the broken line portion shown in Fig. 4(C). The effect is large.

Furthermore, since the bending rigidity of the armature lever (2) is proportional to the second moment of area, it is approximately proportional to tW'. Soi
Therefore, the plate thickness E of the armature lever 1 is set to 1. / n times, even if the width W of the tip of the fixed part with the armature 5 is multiplied by , the rigidity will not decrease L).

When the plate thickness t is reduced, the strength and rigidity in the plate thickness direction decrease, but this does not cause much of a problem because the force acting in the plate thickness direction is small and the amount of deflection and stress in the plate thickness direction are small.

Fig. 5 shows the fixed part between the armature 5 and the armature armature (-1).As shown by the broken line 1' in the figure,
A groove is provided in the armature 5, and the armature lever 1 is embedded in this groove, thereby fixing the rear armature 5 and the armature lever 1.

Other embodiments are shown in FIGS. 6(a) and 6(b).

Fig. 6(a) shows that the width of the position LA where the maximum stress occurs, that is, the farthest point LA from the rotation fulcrum 5A among the fixed parts of the armature 5 and the armature lever l, is widened, and the width of the other parts is made straight. It is gradually becoming narrower.

Figure 6 (b, ) shows the maximum width of armature lever 1;
6(a), but the width of the armature lever 1 is sharp and curved, and the fixed part B to the printing wire 3 is as shown in FIG. 6(a). It has the same width as . Therefore, the mass reduction effect in FIG. 6(b) is greater due to the deletion of the broken line portion.

The reason why the width of the fixing portion B to the printing wire 3 is made the same as in the case of FIG.

〔Effect of the invention〕

As explained above, according to the present invention, the width of the armature lever is widened near the position where the maximum stress occurs, and the width is narrowed in other parts so that the stress generated during printing is smaller than the maximum stress. This allows the armature lever to be made thinner and lighter without sacrificing strength or rigidity, making high-speed printing possible.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a wire dot matrix print head, FIGS. 2 and 3 are diagrams for explaining the process of arriving at the structure of the armature lever according to the present invention, and FIG. 4 is a schematic diagram of a wire dot matrix print head. FIG. 5 is a diagram for explaining an embodiment, FIG. 5 is a diagram showing a fixed portion between an armature and an armature lever, and FIG. 6 is a diagram showing another embodiment of the present invention. 1: Armature lever, 2: Leaf spring, 3: Printing wire, 5: Armature. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 (a) Oha IA

Claims (1)

[Claims] (1) A plurality of armatures and armature levers are fixed to each other using slopes that reduce the plate thickness in the length direction as fixing portions, a driving means for driving the armature, and a plurality of printing wires fixed to the armature levers, In a donmatrix print head that prints a character, figure, etc. by selectively driving a driving means and impacting a printing medium with the tip of the printing wire, the plate thickness of the armature lever is made thinner, and the plate thickness is reduced. The width of the thinned armature lever is gradually increased from the side to which the printing wire is fixed toward the fixed part, with the maximum width near the beginning of the slope of the fixed part, and the width at the end of the slope. A print head characterized by a region that gradually becomes narrower.