JPS6226209Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a print wire drive device used in an impact type dot print head.

FIG. 1 is a half-sectional view for explaining an example of a printing wire drive device in a conventional dot printing head. In the figure, 1 is a printing wire for printing dots, 2 is an armature having the base end of the printing wire 1 fixed to its tip, 3 is one end fixed to the rear end of the armature 2, A leaf spring whose other end is held on the outer periphery of the dot printing head by a holding member 4; 5 is a permanent magnet; 6, 7,
8 is a yoke for forming a magnetic path through which the magnetic flux of the permanent magnet 5 passes; 9 is a core that forms part of the magnetic path and normally attracts the armature by the magnetic force of the permanent magnet 5; A coil 10 is wound around the core 9 and generates a magnetic field that cancels the magnetic field of the permanent magnet 5 when energized.

Next, the operation of the printing wire drive device configured as described above will be briefly explained.

In the rest state, the armature 2 is attracted toward the core 9 by the magnetic force of the permanent magnet 5, so the leaf spring 3 is bent. Therefore, strain energy due to bending is stored in the leaf spring 3. During printing, current is passed through the release coil 10 to generate a magnetic field that cancels the magnetic field of the permanent magnet 5. As a result, the suction force acting on the armature 2 is removed, and the leaf spring 3 uses its stored strain energy to release the armature 2 toward the yoke 8 and drive the printing wire 1 forward.

In this way, in the printing wire drive device having the above configuration, the printing wire 1 is driven by using the strain energy stored in the leaf spring 3 when the armature 2 is attracted. 4 and the other is fixed to the armature 2, forming a so-called both-end fixed beam. Therefore, the spring stress becomes large in order to obtain the desired strain energy. Therefore, conventionally, in order to reduce this spring stress, it was necessary to increase the spring span. Therefore, in the past, there was a certain limit to miniaturizing the dot print head while satisfying a certain print quality and without reducing reliability.

The present invention is an attempt to solve the above-mentioned problems in the printing wire drive device, and the above-mentioned leaf spring is made into a cantilever beam with one end fixed and the other end supported.

The present invention will be explained below with reference to the drawings.

FIG. 2 is a half-sectional view of a dot printing head showing an embodiment of the present invention, and FIGS. 3 and 4 are a sectional view and a plan view showing details of the armature support portion of the dot printing head shown in FIG. be. In addition, 1 to 1 in the figure
0 is the same component as in FIG.

As shown in detail in FIG. 4, the leaf spring 3 has three arm portions 3a, 3b, and 3c;
A common base 3 that integrally connects a, 3b, and 3c
d. The arms 3a and 3c on both sides are fixed by silver brazing or the like between the yokes 7 and 8 at opposite ends of the common base 3d, and are mainly used for positioning the armature 2. It is something. Therefore,
The spring stress of the arms 3a, 3c is small, and their shapes and dimensions are such that almost no spring force is required. central arm 3b
Unlike the arm portions 3a and 3c, the arm portions are not fixed at opposite ends of the common base portion 3d, but merely abut against the protrusion 8a of the yoke 8. The armature 2 is fixed to a common base 3d on the central axis of the arm 3b in a manner similar to that of a conventional armature. Therefore, the armature 2 is moved by the magnetic field of the permanent magnet 5 into the core 9.
As shown in Figure 3, if the
The arm portion 3b is bent because it is in contact with the protrusion 8a of the yoke 8, and strain energy is stored there.

That is, this arm portion 3b has one end fixed to the armature 2 and the other end fixed to the yokes 7, 8.
It functions as a cantilevered leaf spring that is simply supported by the protrusion 8a without being fixed to the protrusion 8a. Therefore, its shape and dimensions are such that it can accumulate enough strain energy for the printing wire 1 to perform a good printing operation when the suction is released.

As described in detail above, the tip of the arm portion 3b of the spring 3 is only in contact with the protrusion 8a and is not fixed, so the stress required to obtain the spring force necessary for the printing operation is less than that of the conventional one. It only needs to be small compared to other things. Therefore, the spring span can be made smaller than that of the conventional one, and the outer diameter of the dot printing head, which is constructed by arranging a plurality of printing wire drive devices arranged in a ring, can be made considerably smaller.

As described above, according to the present invention, the dot printing head can be miniaturized without deteriorating print quality or reliability.

[Brief explanation of drawings]

Fig. 1 is a half-sectional view showing a conventional example, Fig. 2 is a half-sectional view showing an embodiment of the present invention, and Figs. 3 and 4 show details of the main parts of the embodiment shown in Fig. 2. FIG. 2 is a cross-sectional view and a plan view. 1... Printing wire, 2... Armature, 3...
...Plate spring, 3a, 3b, 3c...Arm part, 8...Yoke, 8a...Protrusion.

Claims (1)

[Claims for Utility Model Registration] It has a leaf spring with one end held between two holding members and the other end fixed to the armature, and when not printing, the armature is attracted to the core by the magnetic force of the permanent magnet. Strain energy is stored in the leaf spring, and when printing, a degaussing coil wound around the core is driven to cancel the magnetic force of the permanent magnet, thereby releasing the strain energy of the leaf spring and fixing it to the tip of the armature. In a printing wire drive device that performs printing by protruding a printing wire, the member on the printing surface side of the holding member is provided with a protrusion that protrudes toward the other holding member, and the leaf spring is provided with a protrusion whose tip is directed toward the armature side. A leaf spring free end is formed at the end opposite to the fixed end of the armature by providing an elongated substantially U-shaped slit, and the leaf spring free end is brought into contact with the protrusion. Printing wire drive device.