JPS6347635B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a novel print head that is high speed and highly reliable.

As shown in Fig. 1, the conventional printing head uses a magnetic circuit composed of a permanent magnet 1. In the standby state, the printing hammer 2 is attracted by the magnetic attraction force of the permanent magnet 1, and during printing operation, the excitation on the magnetic circuit is By energizing the coil 3, a reverse magnetic field is applied to release the attraction of the printing hammer 2, and the elastic force of the leaf spring 4, which is integrally fixed to the hammer 2, moves the printing wheel 5 onto the paper 7 wound around the platen 6. Printing was done by hitting the 8 is an ink ribbon. In this method, the temperature of the print head increases significantly due to the heat generated by the current flowing through the excitation coil 3. Especially when printing at high speed, the temperature rise of the print head reaches nearly 120°C, so it is necessary to ensure sufficient heat dissipation. It was necessary to take this into consideration when designing the print head. Therefore, there is a limit to high-speed printing, and the coil winding process in the print head assembly work is complicated and requires many man-hours, which is a factor in high costs. Furthermore, since the coil has an inductance, there is a limit to the printing speed.

In order to solve the above-mentioned drawbacks, the print head of the present invention does not use any excitation coil and mechanically adjusts the permeance of the magnetic circuit made of a permanent magnet or a high permeability magnetic material. The purpose is to release the attraction of the printing hammer and obtain printing operation by changing it by moving it in and out.It forms a magnetic loop made of a permanent magnet or a high permeability magnetic material, and prints within this magnetic loop. A hammer is provided, and the printing hammer is driven by opening and closing the magnetic loop.

The present invention will be described below based on drawings showing embodiments. First, the first embodiment will be explained based on FIGS. 2 to 5 showing the first embodiment. In the figure, 11 is a yoke, and a permanent magnet 12 is attached to one end of the yoke 11, and a printed hammer tip 13 is fixed to the tip of the other end of the yoke 11, and the base end of a leaf spring armature 14 made of a magnetic material. is fixed with screws etc. 15 is the yoke 11
A yoke is attached to the yoke via a non-magnetic frame 16, and is formed in an L shape, one end of which faces the tip of the armature air 14, the other end of which faces the permanent magnet 12 at a distance, and is connected to the yoke. Iron 11, permanent magnet 12, and armature air 14 constitute a magnetic circuit. In front of the armature air 14 is a flexible type wheel 17 made of resin or the like.
is arranged so that printing is performed on the paper 20 wound around the surface of the platen 18 via the ink ribbon 19 by the impact of the printing hammer chip 13 on the armature air 14 in the direction of the platen 18. Further, the printing head section 21 consisting of the yoke 11, the permanent magnet 12, the printing hammer chip 13, the armature air 14, the yoke 15 and the non-magnetic frame 16 is mounted on a carriage 22.
is guided by the carriage guide shaft 23 and reciprocates opposite the platen 18. The type wheel 17 is formed into a petal shape as shown in FIG. 5, and has a type 24 formed at its tip. The type wheel 17 is fixed to a type selection motor 25 attached to the carriage 22, and the rotation of the motor 25 is controlled so that a desired type 24 can be selected. 26 is a magnetic shielding disk, which is connected to the motor 2 fixed to the carriage 22.
It is fixed to the shaft 27a of No. 7 with screws or the like.
Further, as shown in FIG. 4, this magnetic shielding disk 26 has through holes 2 arranged at equal intervals on the same circumference near the outer periphery.
8 and magnetic bodies 29 are arranged alternately, and are rotatably arranged between the yoke 15 and the permanent magnet 12 of the printing head section 21, so as to change the permeance of the magnetic circuit of the printing head section 21. In addition, an ink ribbon drive shaft 3 is located at the center of the magnetic shielding disk 26.
0 is integrally formed, and the ink ribbon cassette 31
It is configured to be removably fitted into an ink ribbon feed roller 32 housed inside. Furthermore, the magnetic shielding disk 26 is connected to a rotating disk sensor 33.
The rotation of the print head 21 is precisely controlled, and the permeance of the magnetic circuit of the print head section 21 is also precisely controlled.

Next, the operation will be explained according to FIG. Figure 3A
indicates a print standby state. In this state, the magnetic body 29 of the magnetic shielding disk 26 is interposed between the permanent magnet 12 and the yoke 15. At this time, the magnetic circuit of the print head section 21 constitutes a closed magnetic path by the yoke 11, the permanent magnet 12, the armature air 14, and the yoke 15. That is, the armature air 14 is attracted by the yoke 15, and the printing hammer tip 13 is in a printing standby state. Here, the elastic force by the armature air 14 is fs, the printing force is F, the magnetic attraction force is fφ ₁ ,
Let the magnetic force at the time of shielding be fφ ₂ . However, force due to magnetic velocity φ ₁ = fφ ₁ [Figure 3 A] Force due to magnetic velocity φ ₂ = fφ ₂ [Figure 3 B] Also, fφ ₁ > fs... φ ₁ ≫φ ₂ ... fφ ₂ ≪fs . . . F=fs ₁ −fφ ₂ . . . Since the print head section 21 is configured so that the following four equations hold true, the above-mentioned print standby state is established.
Next, FIG. 3B shows the printing operation state. Now, the magnetic shielding disk 26 is rotated by the motor 27,
When the rotary disk sensor 33 controls its position and the through hole 28 is interposed between the permanent magnet 12 and the yoke 15, the magnetic circuit of the print head section 21 becomes an open magnetic path. In other words, the above formula and formula hold,
The printing hammer tip 13 strikes the ink ribbon 19 and the type wheel 17 to form characters on the paper 20, thus completing a printing operation.
When the magnetic shielding disk 26 is further rotated to the state shown in FIG. 3A, the printing hammer tip 13 is placed in a standby state. Therefore, by continuously rotating the magnetic shielding disk 26, continuous printing can be performed and a high-speed printing head can be obtained.
In addition, since the ink ribbon drive shaft 30 is integrally formed with the magnetic shielding disk 6, the ink ribbon 19 is fed in synchronization with the printing operation, so there is no need for a motor for driving the ink ribbon, and the configuration can be simplified. This makes it easy to use, reduces costs, and allows for higher speeds. Furthermore, since the print head with the above configuration does not require an excitation coil, there is no need to consider the inductance of the coil, and there is no temperature rise due to the coil's generation of heat, and there is no need to consider heat dissipation design. It is possible to reduce the size of the head and provide a print head with high reliability and high speed. Further, since there is no excitation coil, the number of assembly steps can be reduced, and the cost can be reduced by eliminating the need for the motor for driving the ink ribbon. In the above embodiment, the permanent magnet 12 is attached to the printing head section 21.
A magnetic circuit is constructed by arranging the magnetic shielding disk 2.
Although the permeance of the magnetic circuit was changed in step 6, the main body side of the magnetic loop consisting of the yoke 11, permanent magnet 12, armature air 14, and yoke 15 was all made of a high magnetic permeability magnetic material, and the magnetic shielding disk 26 A similar effect can be obtained by changing the permeance of the magnetic circuit by configuring the side with a permanent magnet.

Furthermore, the magnetic shielding disk 26 is made of a high magnetic permeability magnetic material,
For example, they can be formed of pure iron or sulfur steel plate, etc., in a petal shape as shown in FIG. 6, or with openings 34 provided at equal intervals as shown in FIG. That is, various modifications can be made without departing from the spirit of the invention.

The print head of the present invention can be implemented as described above, and the permeance of a magnetic circuit made of a permanent magnet or a high permeability magnetic material can be changed mechanically without using any excitation coil. Alternatively, the printing hammer can be driven by changing the permanent magnet by moving it in and out.Therefore, there is no need to take the coil heat into consideration in the design, and the structure is simple, small, highly reliable, and high speed. An inexpensive print head can be provided.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of main parts showing a conventional example, Figs. 2 to 5 show a first embodiment of the present invention, Fig. 2 is a cutaway front view of main parts, and Figs. 3 A and B are print heads. FIG. 4 is a plan view of the magnetic shielding disk, FIG. 5 is a front view of the type wheel, and FIGS. 6 and 7 are views of the magnetic shielding disk in other embodiments of the present invention. FIG. 11... Yoke, 12... Permanent magnet, 13... Printed hammer chip, 14... Armature, 15
... Yoke, 17 ... Type wheel, 18 ... Platen, 19 ... Ink ribbon, 20 ... Paper, 2
1... Print head section, 22... Carriage, 25
...Type selection motor, 26...Magnetic shielding disk, 27...Motor, 28...Through hole, 29...
...Magnetic material.

Claims (1)

[Scope of Claims] 1. A magnetic loop made of a permanent magnet is formed, a printing hammer is provided in the magnetic loop, and the magnetic loop is opened and closed by moving a high permeability magnetic material into and out of the magnetic loop main body. , a printing head which performs a printing operation by suctioning and separating the printing hammer. 2. A patent claim in which the magnetic loop main body side is made of a high magnetic permeability magnetic material, and the magnetic loop is opened and closed by moving a permanent magnet into and out of the magnetic loop main body, and a printing hammer is attracted and detached to perform a printing operation. A print head according to item 1 of the range. 3. The printing head according to claim 1, wherein the movement of the high magnetic permeability magnetic material into and out of the magnetic loop body is performed using the rotational force of a motor. 4. The printing head according to claim 2, wherein the permanent magnet is moved in and out of the magnetic loop body using the rotational force of a motor. 5. Claim 1, in which the movement of a permanent magnet or a high permeability magnetic material into and out of a magnetic loop and the feeding drive of an ink ribbon are performed by the same drive mechanism, and the printing operation and the feeding operation of the ink ribbon are synchronized. The print head described in paragraphs 1 and 2.