JPS59150755A - Dot impact printing head - Google Patents

Abstract

PURPOSE:To make it possible to increase effective magnetic flux, by providing a permanent magnet in the vicinity of an armature through a leaf spring in a state separated from an electromagnet mechanism while further forming a secondary magnetic path in addition to the main magnetic path of the permanent magnet. CONSTITUTION:A main magnetic path comprises a course starting from a permanent magnet 21 and reaching a ring shaped yoke 20 through a yoke 22, an armature 17, a leaf spring 18, a core 14a, a base plate 13, a core 14b, a spacer 19 and a leaf spring 18 while a secondary magnetic path starts from the permanent magnet 21 and returns thereto through the yoke, 22 the armature 17, the leaf spring 18 and the ring shaped yoke 20. Herein, when a current is supplied to exciting coils 15a, 15b for printing, the magnetic fluxes of the cores 14a, 14b of the main magnetic path are eliminated and the attracting force of the armature 17 is also eliminated while a dot pin 16 is projected by the leaf spring 18 to perform printing. By this mechanism, attracting force is more effectively acted by the permanent magnet in the vicinity of the armature, a non- printing time is made correct, the interference with the adjacent coil is reduced by two exciting coils, the leak of magnetic flux is suppressed by the secondary magnetic path and high quality printing can be performed.

Description

[Detailed description of the invention] (Technical field) The present invention relates to dot printheads.

The dot printing head uses a spring-charged dot printing system that deflects and eliminates the deflection of a leaf spring by the mutual magnetic flux formed by a permanent magnet and an excitation coil with a core, and transmits the action of the leaf spring to the dot pin for printing. There is a head.

By more effectively forming the magnetic flux by fully operating the leaf springs, even more effective printing can be achieved.

The present invention is to provide a dot impact print head that can form this magnetic flux even more effectively.

(Prior Art) A conventional dot impact print head will be described below with reference to the drawings.

Fig. 1 is a side sectional view of a conventional dot impact print head, Fig. 2 is a plan view thereof, Fig. 3 is a partial side sectional view of the dot impact print head showing a non-printing state, and Fig. 4 shows a printing state. FIG.

In the figure, 1 is a base plate, 2 is a core provided radially on the base plate 1, 3 is an excitation coil arranged corresponding to each core 2 and constitutes an electromagnet mechanism, and 4 is a core 2 that constitutes an electromagnet mechanism. An annular permanent magnet is magnetized on the base plate 1 surrounding the excitation coil "3," and 5 is an annular yoke similarly fixed on the permanent magnet 4.

6 is a dot pin, and 7 is an armature that fixes one end of the dot pin 6 at the end □ and is arranged radially converging on a leaf spring to be described later, and these constitute a printing element.

8 is a circular plate-shaped leaf spring 9 which fixes the armature 7 having the dot pin 6 and is biased by the magnetic flux of the permanent magnet 4;
9 is a spacer that determines the amount of deflection of the leaf spring 8; 10 is a flat yoke;

The leaf spring 8 having the armature 7 is mounted on the annular yoke 5 via a spacer 9, and a flat plate-like yoke 10 is fixed thereon by loosely fitting the armature 7 into a groove thereof.

Reference numeral 11 denotes a mounting frame containing the dot pin 6, and 12 denotes a wire guide provided within the mounting frame 11 to support the movement of the dot pin 6.

The conventional dot impact print head is constructed as described above, and its printing and non-printing states will be explained below.

First, the non-printing state will be explained with reference to FIG. still,
The arrow in the figure indicates the main magnetic path, which is the magnetic flux formed by the permanent magnet 4.

In this case, since the excitation coil 3 is not energized, a main magnetic path of the permanent magnet 4 is formed.

The main magnetic path is from the permanent magnet 4 to the annular yoke 5 above it.
The spacer 9, the leaf spring 8, the flat yoke 10, the armature 7, the leaf spring 8, the core 2, and the diameter from the base plate 1 returning to the permanent magnet 4.

While this main magnetic path is being formed, an attractive force is generated between the armature 7 and the core 2, and the plate spring 8 is biased toward the core 2 by the attractive force against its own elasticity, and the armature 7 is biased toward the core 2. It is adsorbed by 2.

Therefore, the dot pin 6 fixed to the armature 7 is attached together with the armature 7 by the amount of deflection of the leaf spring 8 set by the spacer 9, and the dot pin 7 is pulled into the space 11 and twisted.
Although not shown here, does not protrude from the tip of the mounting case 11, and therefore is not printed.

Next, the printing state will be explained using FIG. 4.

The excitation coil 3 is energized and generates magnetic flux.

This magnetic flux has the effect of erasing the main magnetic path of the permanent magnet 4 during non-printing.

Therefore, the attractive force between the armature 7 and the core 2 is also eliminated, and the leaf spring 8 eliminates the bias by its own elastic force, causing the dot pin 6 together with the armature 7 to protrude forward by the amount of the bias.

At this time, although not shown, the tip of the dot pin 6 protrudes from the tip of the mounting case 11. Therefore, printing is performed.

Then, when the power supply is stopped at an appropriate timing before and after the end of printing, the main magnetic path by the permanent magnet 4 is again formed as described above, and the armature 7 is attracted to the core 2 and becomes in a non-printing state.

In this manner, printing is performed by selectively exciting the excitation coil 3 to drive the dot pin 6.

However, such a structure has the following drawbacks.

This is because the permanent magnet 4 is far from the air gap between the armature 7 and the core 2, so the magnetic flux of the permanent magnet 4 is
This has the disadvantage that it does not work effectively as a suction force in the air gap.

Furthermore, if multiple excitation coils are excited at the same time, the magnetic flux of the permanent magnet 4 will not flow through the core 2 adjacent to the permanent magnet 4, so the air gap outside the permanent magnet 4 will be closed as shown by the solid line in FIG. This creates a magnetic flux that passes through it. In addition,
There is a drawback that the magnetic flux of the excited excitation coil 3 acts on the core 2 of the other unexcited excitation coil 3, increasing the magnetic flux of the permanent magnet 4 passing through the unexcited core 2.

This unnecessarily generated magnetic flux interferes with each other and increases the magnetic resistance of the magnetic path, which slows down the operation of the leaf spring 8, resulting in a disadvantage that either the desired printing cannot be obtained or the drive current increases.

(Objective of the Invention) Therefore, the present invention increases the effective magnetic flux by bringing the permanent magnet closer to the air gap between the armature and the core, and reduces interference between the electromagnets to consistently obtain effective, uniform, and high-quality printing. It is particularly aimed at overcoming the drawbacks of the prior art.

(Structure of the invention) Its characteristics are as follows.

A permanent magnet is placed on the side plate of the armature so as to surround the armature. Alternatively, place it above the armature with a yoke.

Two excitation coils each having a core arranged radially on the base plate are provided for one printing element. In some cases, one piece may be sufficient.

In this way, by creating a structure in which the electromagnet part by the excitation coil having a core and the part to which the permanent magnet is attached are separated via a leaf spring, another core can be placed outside the main magnetic path passing through the core of the permanent magnet. A slave magnetic path is always formed which returns from the leaf spring to the permanent magnet without passing through it.

During printing, the main magnetic path of the core portion of the permanent magnet is erased, but the magnetic flux of the permanent magnet can be allowed to flow through the always formed sub-magnetic path, and no magnetic flux leaks to others.

The magnetic flux for main magnetic path cancellation formed by the excitation coil is caused by rotating between the cores of the two excitation coils.
This can reduce interference with the cores of other unexcited excitation coils.

(Example) Three embodiments of the present invention will be described below.

FIG. 5 is a side sectional view of a dot impact print head showing the first embodiment of the present invention, FIG. 6 is a plan view thereof, and FIG. 7 is a partial side sectional view of the dot impact print head showing a non-printing state. , FIG. 8 is a sectional view of the same side in a printed state.

In the figure, 13 is a base plate, 14a.

14b is 2 for 1 printing element on the base plate 13.
The cores 15a and 15b, which are double formed radially toward the center so that the cores 15a and 15b are arranged, are excitation coils attached to the cores 14a and 14b. It constitutes an electromagnet mechanism.

16 is a dot pin, and 17 is an armature whose end portion is fixed to one end of the dot bin 16, and these constitute a printing element.

Reference numeral 18 designates a circular plate-shaped leaf spring that drives the dot bin 16 by fixing and biasing the armature 17, 19 a spacer that determines the amount of deflection of the leaf spring 18, and 20 an annular yoke.

The integrated dot bin 16, armature 17, and leaf spring 18 are connected to the core 14b in correspondence with the radial electromagnet mechanism.
A plate spring 18 is attached to the top via a spacer 19, and an annular yoke 20 is further arranged on top of the plate spring 18.

21 is a permanent magnet fixed on the annular yoke 20, and the permanent magnet 21 is attached to the armature 1 on the outer periphery of the animation
It is arranged around 7.

22 is a yoke mounted on the permanent magnet 21 by loosely fitting the armature 17 into a groove thereof; 23 is a dot pit 16;
a mounting frame 24 mounted on the yoke 22 and containing the
is a wire guide for the dot pin 16 disposed within the mounting frame 23.

The printing and non-printing states of the first embodiment, which has a double structure in which the permanent magnet 21 is provided near the armature 17 and two electromagnets correspond to one printing element, will be described below.

First, the non-printing state will be explained using FIG. 7.

Arrows indicate a main magnetic path and a sub magnetic path formed by the magnetic flux of the permanent magnet 21 during non-printing.

As shown in the figure, the main magnetic path is transmitted from the permanent magnet 21 to the yoke 22, from its inner wall to the armature 17, and then from the leaf spring 18, the core 14a1 base plate 13, the core 14b1 spacer 19, the leaf spring 18, the annular York 20
, which is the path returning to the permanent magnet 21.

The secondary magnetic path is transmitted from the permanent magnet 21 to the yoke 22, and separate from the main magnetic path that is transmitted from the inner wall of the permanent magnet 21 to the armature 17 and then to the core 14a. This is the path from the system-like yoke 20 to the permanent magnet 21. This slave magnetic path is formed by the magnetic flux of the permanent magnet 21 that is always generated regardless of printing or non-printing.

The main magnetic path of this permanent magnet 21 is between the armature 17 and the core 1.
The dot pin 16 fixed to the armature 17, which moves together, is installed inside the case 23. It is pulled in by the amount of deflection of the leaf spring 18.

Although not shown here, the tip of the dot pin 16 is housed inside the mounting case 23, and the tip of the dot pin 16 does not protrude from the tip of the mounting case 23.
Therefore, printing is not performed.

Next, the printing state will be explained using FIG. 8.

First, the excitation coil 15at15b is energized.

In addition, a new magnetic flux is formed in the cores 14a*j4b by a rotating flow in the opposite direction to the main magnetic path, and the magnetic flux flowing in the cores 14a and 14b portions of the main magnetic path is erased. become.

In this way, since only the main magnetic path flowing through the cores 14a and 14b is erased during printing, the slave magnetic path is not erased but is formed.

In this way, when the main magnetic path is eliminated, the attractive force between the armature 17 and the core 14a is also eliminated, and the leaf spring 18 uses its elasticity to eliminate the bias and return to its original shape.

The armature 17, which moves together with the leaf spring 18, causes the dot pin 16 integral therewith to protrude forward.

The tip of the dot pin 16 that protrudes as the leaf spring 18 is released will protrude from the tip of the mounting case 23, although it is not shown in the drawings. Therefore, printing is performed.

To end this printing state, the excitation coil 15a is activated at an appropriate timing before or after the end of printing.

When the power supply to 15b is stopped, the cores 14a, 14
A main magnetic path is formed in b, and as described above, the plate spring 18 is deflected, the armature 17 is attracted to the core 14a, the tip of the dot pin 16 is housed in the mounting case 23, and printing is stopped.

In this way, current is turned on and off at appropriate timings to the excitation coils 15a and 15b to form and erase the main magnetic path, thereby driving the dot pin 716 to continue printing.

Next, a second embodiment will be described based on FIG. 9. still,
New explanations of parts similar to those in the first embodiment will be omitted.

FIG. 9 is a partial side sectional view of a dot print head showing an embodiment of silk 2.

In the figure, 25 is a base plate, and 26 is a yoke integrally molded continuously with the base plate 25.

This second embodiment has an electromagnetic mechanism similar to the conventional example on the base plate 25, but the permanent magnet 21
Since the mounting is the same as in the first embodiment, a slave magnetic path can be formed in addition to the main magnetic path.

Next, a third embodiment will be explained based on FIG. 10. Note that new explanations of parts that are the same as those in the first and second embodiments will be omitted.

FIG. 10 is a partial side sectional view of a dot impact print head showing a third embodiment.

27 is an annular yoke having an annular upper end extending inward, 28 is a permanent magnet fixed to the lower surface of the boxwood of the annular yoke 2T, and 29 is a yoke fixed to the lower surface of the permanent magnet 28.

In this third embodiment, the permanent magnet 28 is connected to the annular yoke 27.
They are held together by the yoke 29 and form a three-part unit. This unified annular yoke 27 connects the spacer 19 to the core 14.
The permanent magnet 28 is located above the armature 17.

As described above, in the third embodiment, one printing element has two electromagnetic mechanisms as in the first embodiment, and the permanent magnet 28 is placed near the armature 17 via the leaf spring 18. Since it is disposed above, this function is to form a main magnetic path and a slave magnetic path via the leaf spring 18, as in the first embodiment, and has the cores 14a and 14b. The excitation coil 15ai5b has a structure that can eliminate the formed magnetic flux by rotating it in a direction opposite to the main magnetic path.

(Effects of the Invention) As explained in detail above, in the present invention, the permanent magnet of the dot impact print head is provided near the armature, and in the first and third embodiments, two excitation coils are provided for one print element. This arrangement has the following effects.

In the first embodiment, the attractive force between the shear armature and the core acts more effectively on the permanent magnet near the armature than in the past, making it possible to perform printing more correctly when not printing, and at the same time, the permanent magnet is small. It is also possible to

When the two excitation coils are excited, the magnetic flux flow rotates between the cores of the two excitation coils in the opposite direction to the magnetic flux flow of the main magnetic path, so the main magnetic path is erased. Reduces mutual interference between the excitation coil and other adjacent excitation coils that are not excited. This makes it possible to reduce the decrease in printing pressure and the increase in drive current compared to the prior art.

In addition, this main magnetic path is not related to the permanent magnet, and only the core and base plate parts need to be erased, so the magnetic flux of the permanent magnet becomes a slave magnetic path and can form a flow, which prevents unnecessary magnetic flux leakage to the center. The effect of suppressing formation is reduced, and the main magnetic path can be erased more easily during printing than in the past.

In this way, the adsorption and release of adsorption between the armature and the core, which is the deflection and release of the deflection of the leaf spring, can be done much more clearly than before by using only one dot or multiple dots at the same time. Even when driving dots, it can be done accurately. This enables even more powerful printing even at high speed printing.

Next, in the second embodiment, since the excitation coil is one per one-character element as in the conventional example, it can be used when some mutual interference of the electromagnetic mechanism can be tolerated, and the follower magnetic path is formed as in the first embodiment. In addition to this effect, the base plate annular yoke can be integrally formed by sheet metal processing, which has the effect of providing a dot impact print head with a simple structure and low cost.

The third embodiment only has a structure in which the permanent magnet is placed near the top of the armature in a different location from the first embodiment, and the basic structure for forming the main magnetic path and the slave magnetic path is Since they are the same, it is possible to obtain the same effect as in the first embodiment.

A dot impact print head with such an effect can be used especially for a large number of bins that require high quality printing, for example 16 to 2.
It is very useful to use it for a kanji output dot printer with 0 dot bins.

Further, the embodiment of the present invention can also be applied to a dot line printer by having a linearly expanded structure.

[Brief explanation of the drawings] Figure 1 is a side cross-sectional view of a conventional 4-dot printing head, Figure 2 is a plan view of the same, and Figure 3 is a drive showing a non-printing state.
- A partial side sectional view of a one-dot print head; FIG. 4 is a side cross-sectional view showing the printing state; FIG. 5 is a side sectional view of a one-dot print head showing the first embodiment of the present invention; 6 is a plan view of the same, FIG. 7 is a partial side sectional view of the dot impact print head showing a non-printing state, FIG. 8 is a sectional side view of the same side showing a printing state, and FIG. 9 7'lj: 2nd FIG. 10 is a cross-sectional view of the same side showing the third embodiment, and FIG. 10 is a cross-sectional view of the same side showing the third embodiment. 13... Base plate 14 a * 14 b...
・Core 15a, 15b... Excitation coil 16... Dot bin 17... Armature 18... Plate spring
19... Spacer 20... Annular yoke 21...
・Permanent magnet 22...:I-/23...Mounting frame 24...Wire cut patent applicant Oki Electric Industry Co., Ltd. representative patent attorney Takashi Kanakura @1 l 211m ring 30 Tsumugi 90 25 - 10;

Claims (1)

[Claims] 1. A printing element consisting of a dot pin and an armature is fixed to a leaf spring, a permanent magnet forms a main magnetic path that biases the leaf spring, and the main magnetic path of the permanent magnet is erased to release the bias of the leaf spring. In a dot impact print head that has an electromagnetic mechanism consisting of an excitation coil with a core that forms magnetic flux, a permanent magnet is separated from the electromagnetic mechanism via a leaf spring and placed near the armature, and the electromagnetic mechanism is combined into one printing element. A dot impact print head characterized in that two or one excitation coils each having a core are provided to form a secondary magnetic path in addition to a main magnetic path of a permanent magnet.