JPH0254785B2 - - Google Patents

Description

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

The dot printing head has a spring charge type that biases and eliminates the bias of a leaf spring due to 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. It has a dot printing head.

By more effectively forming the magnetic flux by operating this leaf spring, even more effective printing can be performed.

The present invention is to provide a dot impact printing head that allows this magnetic flux to be formed even more effectively.

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

Fig. 1 is a side sectional view of a conventional dot impact printing head, Fig. 2 is a plan view of the same, Fig. 3 is a partial side sectional view of the dot impact printing head showing a stretched printing state, and Fig. 4 shows a printing state. It is a sectional view of the same side.

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.

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

Reference numeral 8 designates a plate spring having a circular flat plate shape and having a plurality of tongues formed in the centripetal direction, 9 a spacer that determines the amount of deflection of the plate spring 8, and 10 a flat plate yoke.

The leaf spring 8 fixedly supports the armature 7 of the printing element in each tongue piece which is a free end, and the circumferential part which is a fixed end is attached to the annular yoke 5 via a spacer 9. At the top, a flat plate-shaped yoke 10 is fixed with an armature 7 loosely fitted into a groove thereof.

11 is a mounting frame containing the dot pin 6;
12 is a dot pin 6 provided in the mounting frame 11
It is a wire guide that supports the movement of the wire.

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 using FIG. Note that the arrow in the figure indicates the main magnetic path, which is the magnetic flux formed by the permanent magnet 4.

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

The main magnetic path is from the permanent magnet 4 to the annular yoke 5 above, the spacer 9, the leaf spring 8, and the flat yoke 1.
0, the path from the armature 7, leaf spring 8, core 2, and base plate 1 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 leaf spring 8 is biased toward the core 2 by the attractive force against its own elasticity, and the armature 7 It is absorbed by the core 2.

Therefore, the dot pin 6 fixed to the armature 7 is pulled into the mounting case 11 by the amount of deflection of the leaf spring 8 set by the spacer 9 together with the armature 7, and the dot pin 6 is moved to the tip of the mounting case 11, although not shown here. It does not protrude from the surface 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 along with the armature 7 to protrude forward by the amount of the bias.

Although this magnetic dot pin 6 is not shown, its tip 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 connected to the core 2.
will be attracted to the paper and become non-printable.

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.

That is, permanent magnet 4 is connected to armature 7 and core 2.
Because the air gap between them is far away, the permanent magnet 4
The disadvantage is that the magnetic flux does not work effectively as an attraction in the air gap.

Also, when multiple excitation coils are excited at the same time,
Since the magnetic flux of the permanent magnet 4 no longer flows through the core 2 adjacent to the permanent magnet 4, a magnetic flux passing through the air gap outside the permanent magnet 4 as shown by the solid line in FIG. 4 is formed. In addition, the magnetic flux of the illustrated exemplary coil 3 acts on the core 2 of the other non-illustrated exemplary coil 3, so that the unexcited core 2
It has the disadvantage of increasing the magnetic flux of the permanent magnet 4 passing through it.

This unnecessarily generated magnetic flux interferes with each other and increases the magnetic resistance of the magnetic path, slowing down the operation of the leaf spring 8, which not only makes it impossible to obtain a desired print, but also increases the drive current.

(Purpose 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 also reduces interference between the electromagnets to ensure effective, uniform, and high-quality printing at all times. The purpose of this invention is to solve the drawbacks of the conventional technology.

(Structure of the Invention) In order to achieve the above object, the present invention has a plurality of printing elements each consisting of a dot pin and an armature arranged radially such that the dot pin is located in the center, and attached to the free end of a leaf spring with one end fixed. The dots of each printing element are firmly supported, and the armature of each printing element is attracted to the core of the electromagnetic mechanism by the magnetic flux generated from the permanent magnet, thereby biasing the leaf spring.
In a dot-impact printing head that selectively energizes an excitation coil of an electromagnetic mechanism to generate a magnetic flux in the core of the electromagnetic mechanism that cancels out the magnetic flux of the permanent magnet, the leaf spring is restored and the printing element is driven. The permanent magnet is disposed on the opposite side of the electromagnetic mechanism with the leaf spring as a boundary and in the vicinity of the armature, and the leaf spring is arranged so that the magnetic flux of the permanent magnet returns to the permanent magnet through the armature and the core of the electromagnetic mechanism. It has magnetic permeability to form a magnetic path and a slave magnetic path that returns from the armature to the permanent magnet through the free end of the leaf spring, inside the leaf spring, and the fixed end of the leaf spring.

According to this configuration, during printing, the magnetic flux of the permanent magnet is erased in the core part of the main magnetic path, but the magnetic flux of the permanent magnet can be allowed to flow to the slave magnetic path that is always formed, and the magnetic flux is not leaked to others. do not have.

By rotating the main magnetic path erasing magnetic flux formed by the excitation coil between the cores of the two excitation coils, interference with the cores of other excitation coils that are not excited can be reduced. .

(Examples) Below, three examples of the present invention will be described.

FIG. 5 is a side sectional view of a dot impact printing 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 printing 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 a double core formed radially toward the center so that two cores are arranged for one printing element on the base plate 13; 15a and 15b are cores 14;
excitation coils 15a, 15 that are attached to cores 14a, 14b and have cores 14a, 14b;
b constitutes an electromagnet mechanism.

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

Reference numeral 18 designates a plate spring having a circular flat plate shape and having a plurality of tongues formed in the centripetal direction, 19 a spacer that determines the amount of deflection of the plate spring 18, and 20 an annular yoke.

The leaf spring 18 fixedly supports the armature 17 of the printing element in each tongue which is a free end, and has a fixed end such that each armature 17 is located on the core 14a corresponding to the radial electromagnetic mechanism. The core 14b is inserted through a spacer 19 whose circumference is annular.
An annular yoke 20 is attached on top of the yoke.
are arranged.

Reference numeral 21 denotes a permanent magnet fixed on the annular yoke 20, and the permanent magnet 21 is arranged around the armature 17 on the outer periphery of the armature 17.

22 is a yoke in which the armature 17 is loosely fitted into its own groove and is mounted on the permanent magnet 21; 23 is a mounting frame that includes the dot pin 16 and is mounted on the yoke 22; and 24 is a dot pin 16 disposed within the mounting frame 23. This is a wire guide.

The printing and non-printing states in 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.

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 through the leaf spring 18, core 14a, base plate 13, core 14b, spacer 19,
This path returns to the leaf spring 18, the annular yoke 20, and 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 to the armature 17 and then to the core 14a. This is the path from the annular 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 whether printing is performed or not.

The main magnetic path of this permanent magnet 21 is the armature 17
An attractive force is generated between the core 14a and the plate spring 18 against its elasticity, and the core 14 is moved by the thickness of the spacer 19.
Since the dot pin 16 fixed to the armature 17 that moves together with the dot pin 16 is pulled into the mounting case 23 by the amount of bias of the leaf spring 18.

This is not shown here, but dot pin 1
The tip of the dot pin 16 is housed in the attachment case 23, and the tip of the dot pin 16 does not protrude from the tip of the attachment case 23, so that no printing is performed.

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

First, the excitation coils 15a and 15b are energized.
Then, new magnetic flux is formed in the cores 14a, 14b by a rotating flow in the opposite direction to the main path, and the magnetic flux flowing in the cores 14a, 14b portion of the main magnetic path is erased.

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 formed without being erased.

In this way, when the main magnetic path is erased, armature 1
7 and the core 14a is also eliminated, and the leaf spring 1
8 uses its elasticity to eliminate the deviation 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 by the release of the bias of the leaf spring 18 will protrude from the tip of the mounting case 23, although it is not shown in the drawings. Therefore,
Printing is done.

To end this printing state, the excitation coil 15a, at an appropriate timing before and after the end of printing,
When the power supply to 15b is stopped, the cores 14a, 1 are turned off again.
A main magnetic path is formed in 4b, and as described above, the leaf spring 18 is biased, the armature 17 is attracted to the core 14a, and the tip of the dot pin 16 is attached to the mounting case 23.
and printing is stopped.

In this manner, the dot pins 16 are driven to continue printing by turning on and off the current to the excitation coils 15a and 15b at appropriate timings to form and erase the main magnetic path.

Next, a second embodiment will be described based on FIG. 9. Note that 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 printing head showing a second embodiment.

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 since the permanent magnet 21 is attached in the same way as the first embodiment, a secondary magnetic path is provided in addition to the main magnetic path. can be formed.

Next, a third embodiment will be described 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 printing head showing a third embodiment.

27 is an annular yoke having a flange formed by extending the annular upper end inward; 28 is a permanent magnet fixed to the lower surface of the flange of the annular yoke 27; 29 is a permanent magnet 28;
It is a yoke fixed to the bottom surface.

In this third embodiment, a permanent magnet 28 is sandwiched between an annular yoke 27 and a yoke 29 to form a three-piece unit. This three-part annular yoke 27 has a spacer 19 disposed on the core 14b and is fixed on a leaf spring 18 attached thereto, and the permanent magnet 28 is located above the armature 17. .

In this way, in the third embodiment, one printing element has two electromagnetic mechanisms as in the first embodiment,
Since the permanent magnet 28 is disposed above the armature 17 via the leaf spring 18, this function forms a main magnetic path and a slave magnetic path via the leaf spring 18, as in the first embodiment. The excitation coil 15 has cores 14a and 14b.
a15b has a structure in which the formed magnetic flux can be erased by rotation that flows in the opposite direction to the main magnetic path.

(Effects of the Invention) As described above in detail, in the present invention, the permanent magnet of the dot impact printing head is provided near the armature, and in the first and third embodiments, two excitation coils are provided for one printing element. Once placed, it has the following effects:

In the first embodiment, the attraction force between the armature and the core acts more effectively than before due to the permanent magnet near the armature, making it possible to perform ratio printing more accurately and at the same time making it possible to downsize the permanent magnet. becomes.

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. This has the effect of reducing 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 erasure has nothing to do with 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, preventing unnecessary magnetic flux leakage to others. It has the effect of suppressing formation, and the main magnetic path can be erased more easily during printing than in the past.

In this way, the adhesion 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. This can be done accurately even when driving. This enables more accurate 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, since the base plate and the annular yoke can be integrally formed by sheet metal processing, it has the effect of providing a dot impact printing 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 forming the main magnetic path and the slave magnetic path is different from the first example. Since they are the same, the same effects as in the first embodiment can be obtained.

A dot impact printing head with such an effect is used especially for a large number of pins that require high quality printing.
For example, it is very useful to use it in a dot printer that outputs kanji characters with 16 to 20 dot pins.

In addition, the embodiment of the present invention can be applied to a dot line printer by developing the structure in a linear manner.

[Brief explanation of the drawing]

Fig. 1 is a side sectional view of a conventional dot impact print head, Fig. 2 is a plan view of the same, 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. 5 is a side sectional view of the dot impact printing head showing the first embodiment of the present invention, FIG. 6 is a plan view thereof,
FIG. 7 is a partial side sectional view of the dot impact printing head showing a non-printing state, FIG. 8 is a same side sectional view showing a printing state, and FIG. 9 is a same side sectional view showing a second embodiment. FIG. 10 is a sectional view of the same side showing the third embodiment. 13...Base plate, 14a, 14b...
Core, 15a, 15b... Excitation coil, 16...
Dot pin, 17... Armature, 18... Leaf spring, 19... Spacer, 20... Annular yoke,
21...Permanent magnet, 22...Yoke, 23...Mounting frame, 24...Wire guide.

Claims (1)

[Scope of Claims] 1. A plurality of printing elements consisting of dot pins and armatures are arranged radially with the dot pins located in the center, and the armature of each printing element is fixedly supported on the free end of a leaf spring whose one end is fixed. , the armature of each printing element is attracted to the core of the electromagnetic mechanism by the magnetic flux generated from the permanent magnet, thereby biasing the leaf spring, selectively energizing the excitation coil of the electromagnet mechanism, and causing the core of the electromagnetic mechanism to In a dot impact printing head that restores a leaf spring and drives a printing element by generating a magnetic flux that cancels the magnetic flux of the magnet, the permanent magnet is located on the opposite side of the electromagnetic mechanism with the leaf spring as the border and in the vicinity of the armature. At the same time, the magnetic flux of the leaf spring and the permanent magnet is connected to the armature,
The magnetic permeability forms a main magnetic path through the core of the electromagnetic mechanism and back to the permanent magnet, and a secondary magnetic path from the armature through the leaf spring free end, within the leaf spring, through the leaf spring fixed end and back to the permanent magnet. A dot impact printing head characterized by having: