JPH035993B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention This invention relates to a dot printer head.

Technical background of the invention and its problems This type of printer operates an armature by the excitation action of a coil, and the operation of the armature causes the needle to collide with the platen to perform printing. It is more convenient for wiring to arrange the coils that drive the armature on the outside.
Conventionally, there is one shown in FIGS. 1 and 2.

That is, a coil 3 is attached to each of a plurality of cores 2 integrally formed on a yoke 1, and an armature 5 that causes a needle 4 to collide with a platen by the excitation action of these coils 3 is started around a rotation fulcrum 6. It is set up in any shape. A notch 8 is formed on both sides of the armature 5 and is held by a guide 7. This guide 7 is the yoke 1
It is located in the opposite plane. Printing is performed by exciting the coil 3 and attracting the armature 5 to the core 2. At this time, magnetic flux flows from the core 2 to the armature 5.
The liquid flows through the yoke 1 and returns to the core 2. For printing, it is necessary to increase the suction force in the core 2, and for this purpose, it is necessary to increase the area of the facing surfaces of the armature 5 and the yoke 1. However, in the case shown in FIGS. 1 and 2, it is necessary to form a notch 8 in the armature 5 located in the plane facing the yoke 1 due to the position of the guide 7. In order to increase the facing area, the radial width l ₃ of the yoke 1 must be increased. If the distance from the rotational fulcrum 6 to the center of the core 2 is l ₁ and the distance from the rotational fulcrum 6 to the striking point of the tip needle of the armature 5 is l ₂ , then the increase in l ₃ is
By increasing l ₁ , the air gap G becomes larger. As a result, sufficient suction force cannot be obtained in the core 2. Also, as l ₁ increases, the lever ratio
l ₂ /l ₁ becomes smaller and the equivalent mass of the armature 5 increases, which has the disadvantage that high-speed printing is no longer possible and power consumption increases.

Purpose of the Invention The present invention was made in view of the above points, and an object thereof is to provide a dot printer head that can increase the suction force in the core, reduce the equivalent mass of the armature, perform high-speed printing, and reduce power consumption. That is.

SUMMARY OF THE INVENTION This invention supports a rotational fulcrum of an armature by a yoke, and drives the armature in the printing direction by the excitation action of a coil arranged outside the yoke. A notch that engages with the guide is located between the rotation fulcrum of the armature and the tip on the needle side, and is formed on both sides of the armature, thereby shifting the facing position of the notch and the yoke, and further connecting the yoke in an annular shape. Therefore, the distance in the radial direction of the yoke is reduced while satisfying the condition of keeping the facing area of the yoke and armature constant, and this makes it possible to reduce the distance from the pivot point of the armature to the core. Therefore, the ratio of the distance from the rotation fulcrum to the tip of the armature is increased, the equivalent mass of the armature is kept small, the armature is operated at high speed, and the air gap is made small to obtain sufficient suction force. By forming an edge-shaped rotational fulcrum on the armature and joining this rotational fulcrum to the yoke, the inner circumferential edge of the surface of the yoke facing the armature can be defined in a circular shape. The structure is such that it can be easily formed.

Embodiment of the Invention An embodiment of the invention will be described with reference to FIGS. 3 to 5. Reference numeral 10 denotes a guide frame made of plastic, and needle guides 12, 13, and 14 for slidably holding a plurality of needles 11 are fixed to this guide frame 10. Further, a ring-shaped yoke 15 is screwed to the guide frame 10. A plurality of cores 17 to which coils 16 are attached are integrally formed on the outer circumferential side of the yoke 15 and arranged radially.
The armature 18 facing the core 17 and the yoke 15 has notches 19 on both sides, and by fitting an armature guide 20 integrally formed with the guide frame 10 into the notches 19, the armature 18 can rotate around the pivot point 21. It undulates and is always urged in the return direction by a spring 22. Also,
Guides 23 are also formed in the guide frame 10 to prevent swinging on both sides of the tip of the armature 18. Further, the yoke 15 has a disk portion 24 on the inner circumferential side, and an armature stopper 25 is attached to this disk portion 24.
is retained. The rotation fulcrum 21 has an edge shape that is orthogonal to the radial direction of the yoke 15 by forming a concave surface 26 on one surface of the armature 18. Further, the notch 19 is positioned between the rotation fulcrum 21 and the tip on the needle 11 side.

In such a configuration, when the coil 16 is energized, the armature 18 is attracted by the suction surface 27 of the core 17 and rotates about the pivot point 21, causing the needle 11 to impact the platen and print.

At this time, since the notch 19 is located between the rotation fulcrum 21 supported by the yoke 15 and the tip on the needle 11 side, the opposing positions of the notch 19 and the yoke 15 are largely shifted, and the armature of the yoke 15 is The surface supporting the armature 18 is continuous in an annular manner, so that the opposing area between the armature 18 and the yoke 15 can be increased to maintain good magnetic permeability.
Furthermore, it is possible to reduce the radial distance l ₃ of the yoke 15 while satisfying this condition. l ₃
With the reduction of , the distance l ₁ from the pivot point 21 to the center of the suction surface 27 can be reduced. Thereby, it is possible to increase the value of l ₂ /l ₁ , assuming that the distance from the rotation fulcrum 21 to the tip of the armature on the needle 11 side is l ₂ . By increasing the value of l ₂ /l ₁ , it is possible on the one hand to reduce the equivalent mass of the armature 18 and to operate the armature 18 with a small suction force, and with the same suction force it is possible to operate the armature 18 at high speed. .
On the other hand, the air gap G becomes smaller and a greater suction force can be obtained, or if the same suction force is maintained, power consumption can be reduced.

In addition, since the armature 18 is formed with an edge-shaped rotation fulcrum 21 by forming the concave surface 26,
This rotation fulcrum 21 can be joined to the substantially outer side of the inner circumferential edge 28 of the yoke 15, so that the inner circumferential edge 28 of the surface facing the armature 18 can be made circular, making it possible to form the yoke 15 very easily. . When the armature 18 is made flat and the joint portion of the flat surface with the inner circumferential edge 28 is used as a pivot point, the inner circumferential edge 28 needs to be polygonal. This is difficult to manufacture compared to a case where the inner circumferential edge 28 is formed circularly.

Effects of the Invention Since the present invention is constructed as described above, the rotational movement relative to the distance from the rotational fulcrum of the armature to the suction surface can be achieved while satisfying the condition of increasing the opposing area between the armature and the yoke in order to improve magnetic permeability. It is possible to increase the ratio of the distance from the fulcrum to the needle tip, which on the one hand reduces the equivalent mass of the armature and allows it to operate at high speed, and on the other hand reduces the air gap and reduces power consumption. can be made smaller,
Furthermore, by forming a protruding edge-shaped rotation fulcrum on the armature, it is possible to define the inner circumference of the surface of the yoke that faces the armature in a circular shape, which makes it possible to form the yoke extremely easily. It has the following effects.

[Brief explanation of drawings]

Figure 1 is a horizontal sectional view of the main part showing the conventional example, Figure 2
The figure is a front view of the main part, FIG. 3 is a horizontal cross-sectional view showing an embodiment of the invention on a reduced scale, and FIG. 4 is a horizontal cross-sectional view of the main part.
The figure is a front view of the main parts. DESCRIPTION OF SYMBOLS 11... Needle, 15... Yoke, 16... Coil, 17... Core, 18... Armature, 19... Notch, 20... Armature guide, 21... Rotation fulcrum, 27... Suction surface.

Claims (1)

[Claims] 1. A plurality of cores to which coils are attached are arranged radially on the outside of an annular yoke, and a plurality of armatures each facing a suction surface of the core and driving a needle are provided, A rotation fulcrum supported by the yoke is formed in these armatures, and a notch supported by an armature guide is formed on both sides of the armature, located between the rotation fulcrum and the tip on the needle side. A dot printer head characterized by: 2 A plurality of cores to which coils are attached are arranged radially on the outside of an annular yoke, and a plurality of armatures each facing a suction surface of the core to drive a needle are provided, and the yoke is attached to these armatures. A rotation fulcrum supported by the plane of the yoke is formed protrudingly with a linear edge perpendicular to the radius of the yoke, and notches supported by armature guides are formed on both sides of the armature between the rotation fulcrum and the needle side. A dot printer head characterized in that the dot printer head is formed between the dot printer head and the tip of the dot printer head.