JPH0211432B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a wire dot matrix print head, and more 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 to apply 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
is released from 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 leading end of the printing medium 10 is connected to the printing medium 10 via the ink ribbon 9.
impact on the platen 11 to print dots.

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. To do this, the armature, which is a moving part,
It is necessary to reduce the mass of the assembly. 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. A printing wire 3 is attached to the armature lever 1. Further, in order to reduce weight, the fixed portion between the armature 5 and the armature lever 1 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, the driving cycle of the printing wire 3 must be further increased. 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 drive means for driving the armature lever. In the dot matrix printing head, which includes a plurality of fixed printing 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 armature The weight of the armature lever is reduced by reducing the plate thickness of the armature lever, and the width of the armature lever with the reduced plate thickness is gradually widened from the side to which the printing wire is fixed toward the fixed part. The fixing portion has a maximum width near the beginning of the slope, and is gradually narrowed toward the end of the slope, thereby preventing a decrease in strength and rigidity due to thinning of the plate.

[Embodiment of the Invention] Hereinafter, an 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 plate It is not possible to reduce the thickness. Therefore, it is necessary to reduce the thickness of the armature lever 1 to reduce its weight. When the plate thickness is reduced, the problem is that the strength and rigidity are reduced. In other words, as the plate thickness becomes thinner, the strength decreases,
This may cause breakage, the contact time with the printing medium becomes longer despite the decrease in rigidity, and the printing wire 3 may catch the ink ribbon 9, and the repulsion when the printing wire 3 hits the printing medium 10 becomes worse. On the other hand, the printing operation becomes slower.

In order to prevent the decrease in strength and rigidity caused by reducing the thickness of the armature lever 1 by increasing the width of the armature lever 1, as shown by the broken line in FIG. The mass increases only in the shaded area, making it even heavier. Therefore, the third
As shown in the figure, 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 maximum width of the armature lever 1 is higher than the armature 5 by the dimension a. Therefore, by a space of dimension a, the members located on the print medium 10 side from the armature assembly are completely covered with the print medium 1.
It must be shifted to the 0 side, and the print head becomes longer. Therefore, the printing wire 3 becomes heavier by the length of the dimension a, and the effect of reducing the weight of the armature assembly as a whole is reduced.

Therefore, it is necessary to widen the width of the armature lever 1 in a way that maximizes the effect of weight reduction.

In the armature assembly shown in FIG. 4a, in which the thickness of the armature lever 1 is reduced, when printing force F is applied to the tip of the printing wire 3 during printing, the stress generated in the armature lever 1 is As shown by the solid line in Figure b, the maximum stress is at the fixed part with the armature 5 and
This occurs at the farthest position 1A from the rotational fulcrum 5A.

This maximum stress must be smaller than the maximum allowable stress of the armature lever 1, as shown by the broken line in FIG. 4b. Therefore, in order to achieve the bending stress shown by the broken line in FIG. 4b, the width of the armature lever 1 is adjusted as shown in FIG. By making it wider 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. Let us consider a case where the thickness of the armature lever 1 is increased by 1/n times. If the width of the 1A section of the armature lever 1 is W, and its plate thickness is t, the maximum stress is 1/
Since it is proportional to tW ² , if the plate thickness t of the armature lever 1 is multiplied by 1/n, the width W of the tip 1A of the fixed part with the armature 5 will be √ of the original width h.
If it is doubled, the armature lever 1 with 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 t×(Wh), the tip 1A of the part fixed to the armature 5
When the width W of the portion is multiplied by √, the armature lever 1 can be made lighter approximately in proportion to √×h.

Furthermore, when comparing the embodiment shown in FIG. 4C and the example shown in FIG. 3, the effect of mass reduction is greater in FIG. 4C due to the deletion of the broken line portion shown in FIG. 4C.

Furthermore, the bending rigidity of the armature lever 1 is proportional to the moment of inertia of the area, and therefore approximately proportional to ^tW3 . Therefore, the plate thickness t of armature lever 1
Even if the width W of the tip of the fixed portion with the armature 5 is multiplied by √, the rigidity will not decrease.

When the plate thickness t is made thinner, the rigidity decreases in the thickness direction, but the force acting in the plate thickness direction is small, and the amount of deflection and stress in the plate thickness direction are small, so this does not cause much of a problem.

FIG. 5 shows a fixed portion between the armature 5 and the armature lever 1. As shown by a 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 armature 5 and the armature lever 1.

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

In Fig. 6a, the width is widened at the position where the maximum stress occurs, that is, the position 1A farthest from the rotation fulcrum 5A among the fixed parts of the armature 5 and the armature lever 1, and the width of the other parts is linear. It is gradually becoming narrower.

In Fig. 6b, the maximum width of the armature lever 1 and its position are the same as in Fig. 6a, but the width of the armature lever 1 narrows rapidly and in a curved manner, and the printing The fixed portion B to the wire 3 has the same width as in FIG. 6a. Therefore, the effect of mass reduction is greater in FIG. 6b due to the deletion of the broken line portion.

The width of the fixing portion B to the printing wire 3 is made the same as that shown in FIG. 6a in order to maintain a fixing force capable of withstanding printing force.

〔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 of the armature lever is widened in other parts so that the stress generated during printing is smaller than the maximum stress. By narrowing the armature lever, the plate thickness of the armature lever can be made thinner and the weight can be reduced without compromising strength and rigidity, thereby enabling high-speed printing.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a wired dot matrix printing 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 an embodiment of the present invention. FIG. 5 is a diagram for explaining an example, and FIG. 5 is a diagram showing a fixed portion between an armature and an armature lever. FIG. 6 is a diagram showing another embodiment of the present invention. 1: Armature lever, 2: Leaf spring, 3: Printing wire, 5: Armature.

Claims (1)

[Claims] 1. A plurality of armatures and armature levers are fixed to each other using slopes that reduce plate thickness in the length direction as fixing parts, a driving means for driving the armature, and a plurality of printing wires fixed to the armature levers, In a dot matrix printing head that prints characters, figures, etc. by selectively driving the driving means and impacting a printing medium with the tip of the printing wire, the plate thickness of the armature lever is made thin, and The width of the armature lever having a thinner plate is gradually widened from the side to which the printing wire is fixed toward the fixed part, and the maximum width is set near the first region of the slope of the fixed part, A printing head characterized in that the slope gradually narrows towards the end area.