JPH01226345A - print head - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a print head (hereinafter abbreviated as print head) for a wire dot printer used as an output terminal for various computers.

BACKGROUND OF THE INVENTION In recent years, print heads have become faster and, for example, 24-dot print heads have been commercialized that can print Kanji characters at 60 to 100 characters per second. (For example, Electric and Telecommunications Public Corporation Research and Practical Application Report Vol. 28, No. 2, A-tight wire dot type kanji printer.)
The conventional print head as described above will be described below with reference to the drawings.

Conventionally, this type of print head has had a configuration as shown in FIG. FIG. 6 is a side sectional view of a conventional print head. In the figure, reference numeral 11 denotes a printing needle whose one end is fixed to the tip of a lever 12, and the tip of the printing needle 11 is guided into a guide hole of a bearing 14 held by a writing body 13. 16 is a leaf spring fixed to one end of the lever 12;
A movable body 16 is fixed to one side of the plate spring 16, and the other end of the leaf spring 16 is sandwiched between the yoke 7 and the ring 18 and fixed with a screw. 19 is a permanent magnet, 2o is a core side wall, 21 is a core pole, and a degaussing coil 22 is attached to the outer periphery of the core pole 21.
is located. A plurality of movable bodies 16 and leaf springs 16 are arranged in a ring shape, and the core pole 21 is connected to the movable body 16.
is placed so as to face the The permanent magnets 19 are arranged in a ring shape on the core side wall 20. York 17
A plurality of protrusions are provided so as to embrace the side surface of the movable body 16.

The operation of the print head configured as described above will be explained below. In the above configuration, permanent magnet 1
The magnetic flux 9 is guided to the movable body 16 via the core side wall 2o and the core pole 21, and is further returned to the permanent magnet 19 via the side surface of the movable body 16, the jaw 17, and the ring 18. Therefore, the movable body 16 is attracted downward by the force of the core pole 21 due to the magnetic flux of the permanent magnet 19, and the leaf spring 16 is in a deflected state. Next, when a current is passed through the degaussing coil 22, the magnetic flux of the permanent magnet 19 is canceled out.

Since the suction force of the warming body 16 decreases, the movable body 16 is accelerated upward by the restoring force of the leaf spring 15.

At this time, the printing needle 11 protrudes from the bearing 14 and impacts an ink ribbon (not shown) to print dots. Furthermore, when the current in the degaussing coil 22 is stopped, the movable body 1
6 is attracted again by the magnetic flux of the permanent magnet 19, so that the printing needle 11 returns to its original position.

Dot matrix printing is performed by operating the printing stylus 11 at appropriate times while scanning the print head left and right with the above operations as one cycle.

Problems to be Solved by the Invention Problems with the conventional print head configured as described above will be described below. If an attempt is made to increase the speed of the print head using such a method, the spring constant of the leaf spring must first be increased in order to improve the responsiveness of the leaf spring. However, the attractive force of the permanent magnet must also be increased accordingly. However, in the magnetic circuit configuration of a conventional print head, the opposing area of the magnetic circuit on the upper surface of the permanent magnet (temporarily assumed to be the north pole) and the magnetic circuit on the lower surface (supposed to be the south pole) is large. In other words, it can be seen that the magnetic flux generated by the permanent magnet is not effectively used to attract the movable body, but rather leaks between the aforementioned opposing magnetic circuits. Therefore, the permanent magnet inevitably becomes large, which poses a major obstacle to miniaturization of the print head. In addition, permanent magnets ensure attractive force,
Conventionally, precious resources such as rare earth magnets, such as samarium cobalt, have been used, which has limited cost reduction.

Furthermore, Japanese Patent Application No. 58-235305 attempts to solve the above-mentioned problem by arranging a permanent magnet near the movable body, but since the contact surface of the yoke with the permanent magnet is located at a lower position than the outer periphery. However, it was difficult to process the joint surface with the permanent magnet. (Refer to Figure 5 1. and Figure 6 of the patent application No. 58-235305)
In FIG. 6 of the same issue, since the joint surface of the yoke 10 with the permanent magnet 9 is flat, there is a drawback that the fringe magnetic flux of the permanent magnet 9 tends to leak.

The present invention solves these conventional problems,
By reducing leakage in the magnetic circuit and providing sufficient attraction with a small permanent magnet, a small, high-speed print head can be realized at low cost.

Means for Solving the Problems In order to solve this problem, the present invention provides a permanent magnet integrally molded in a ring shape, a yoke fixed to one surface of the permanent magnet and having a plurality of grooves, and a yoke of the yoke. A movable body disposed in the groove, a core pole disposed to face one surface of the movable body, a degaussing coil disposed around the outer periphery of the core pole, and a movable body disposed on one surface of the permanent magnet. The permanent magnet, the yoke, the movable body, and the pole of the core are arranged substantially in a straight line.

Effect With this configuration, the opposing area of the magnetic circuit on the upper surface and the magnetic circuit on the lower surface of the permanent magnet is small, and there is little leakage between the opposing magnetic circuits, so the magnetic flux generated by the permanent magnet can effectively attract the movable object. Even a small permanent magnet can generate sufficient attraction force, making it possible to realize a small, high-speed print head at low cost.

Example Below, regarding one example of the present invention, FIGS. 1, 2, and 3.
This will be explained based on the diagram and FIG. In Figure 1,
The difference from the conventional example is the permanent magnet, flat yoke,
Since the structure and configuration of the yoke and the other components are the same, other explanations will be omitted.

FIG. 1 is a sectional view of a print head according to an embodiment of the present invention, FIG. 2 is a detailed sectional view of the same, FIG. 3 is a perspective view of the same, and FIG.
The figure is an enlarged view. In FIG. 1, the permanent grinding stone 9 is bonded to one side of the flat yoke 7, and the yoke 13 is bonded to one side of the permanent magnet 9. The yoke 13 is provided with a plurality of grooves, and the movable body 13 is arranged in the plurality of grooves. The magnetic flux of the permanent magnet 9 is guided to the core pole 21 via the yoke 13, through the side surface of the movable body 16. Furthermore, it passes through the ring 8-1, 8-2 from the core side wall 2o, and is fed back to the permanent magnet 9Vc via the flat yoke 7. Here, as shown in FIG. 2, by setting the gap between the yoke 13 and the movable body 16 in the soil force direction and their opposing area, and the left-right direction gap and their opposing area in an appropriate ratio, the magnetism in the soil direction can be adjusted. The resistance Ru and the riB resistance Rs in the left and right direction can be set, for example, as shown in equation (1).

Ru) 10Rs ・・・・・・・・・・・・ (1
) That is, it can be seen that most of the magnetic flux of the permanent grinding stone 9 flows from the side surface of the yoke 13 to the movable body 16, and therefore no vertical force acts on the movable body 16.

With this configuration, the flat yoke 7, the ring El-1
, 8-2, the core side wall 2o, and the core pole 21 have the same magnetic pole, so that leakage of magnetic flux from the permanent magnet 9 is extremely reduced.

In addition, with this configuration, the flat yoke 7 can be formed flat, which makes it extremely easy to roll. Furthermore, by providing the ring-shaped groove 24 on the joint surface of the permanent magnet 9 of the flat yoke 7, leakage of the fringe magnetic flux of the permanent magnet 9 can be reduced.

Effects of the Invention According to the present invention, the opposing area between the magnetic circuit on the soil surface and the magnetic circuit on the bottom surface of the permanent foundation stone is small, and there is little leakage between the opposing magnetic circuits, so the magnetic flux generated by the permanent magnet can be effectively moved. Because it is used for body suction.

Even a small permanent magnet can generate sufficient attractive force, and a small, high-speed print head can be realized at low cost.

In addition, since the joint surfaces of the flat yoke and the permanent magnet are on the same plane, the flat yoke can be processed easily and with high precision by, for example, surface grinding or lapping. Furthermore, by providing a ring-shaped groove on the joint surface of the flat yoke with the permanent magnet, it is possible to reduce leakage of fringe magnetic flux of the permanent magnet. For example, a permanent magnet with a conventional magnetic circuit configuration having an outer diameter of 65 mm has an outer diameter of 4Q while maintaining the same magnetic attraction force.
It can be reduced to ffllll. This also allows the outer size of the print head to be reduced from the conventional 65 mm to 56 mm.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of a print head according to an embodiment of the present invention, FIG. 2 is a detailed sectional view, FIG. 3 is a perspective view, FIG. 4 is an enlarged view, and FIG. 6 is a conventional print head. FIG. 11... Printing needle, 12... Lever, 1
3... Housing, 14... Bearing, 16...
...Movable body, 7...Yoke, 8-1.8-
2...Ring, 9...Permanent magnet, 16
...Plate spring, 16...Movable body, 20.
... Core side wall, 21 ... Core pole, 2
2...Sakata coil. Name of agent: Patent attorney Toshio Nakao and 1 other person7-
Flat Gogue /4...I Jiai ε-/, 8-z
-Ring 15-° plate bone/3-one housing
22---5th corner, coil I3-yoke Figure 1, 4 Figure 3

Claims (3)

[Claims] (1) A permanent magnet integrally formed into a ring shape, a yoke fixed to one side of the permanent magnet and having a plurality of grooves,
A movable body disposed in the groove of the yoke, a core pole disposed to face one surface of the movable body, a degaussing coil disposed around the outer circumference of the core pole, and the pole and the permanent magnet. 1. A print head comprising a return section for magnetic flux connecting one surface of the print head, wherein the permanent magnet, the yoke, the movable body, and the pole of the core are arranged substantially in a straight line. (2) The print head according to claim 1, wherein the joint surface of the permanent magnet of the flat yoke and the joint surface of the ring of the flat yoke are arranged on the same plane. (3) The print head according to claim 1, characterized in that a ring-shaped groove is provided on the joint surface of the flat yoke with the permanent magnet.