JPH01264856A - Printing head - Google Patents

Abstract

PURPOSE:To realize the extension of life by relaxing the stress applied to the second fulcrum, by supporting the block provided with the second fulcrum by a frame through a leaf spring. CONSTITUTION:In printing, the first stage enlarged part 12 is revolved around the first fulcrum 14 in a clockwise direction by the upward displacement of a drive element 11 due to the supply of a current and the second stage enlarged part 13 is revolved around the second fulcrum 18 in the counterclockwise direction. By this revolution, a printing wire 20 is moved downwardly to perform the printing due to said printing wire 20. Herein, the second fulcrum 18 is provided to a block 21 which is, in turn, supported by a frame 17 through a leaf spring 22. Therefore, since the second fulcrum 18 is elastically supported to have a degree of freedom, the stress applied to the second fulcrum 18 is relaxed to make it possible to prevent breakage.

Description

[Detailed description of the invention] [Summary] A first stage enlarged portion that can rotate around a first fulcrum and a first stage enlarged portion that can rotate around a second fulcrum can compensate for minute displacements when a drive element such as a piezoelectric element is energized. Regarding the print head that prints by expanding into two stages with the second stage enlargement part, the purpose is to alleviate the stress applied to the second fulcrum during printing and to extend the lifespan. a first stage enlarged part that is rotatable in the periphery; a drive element that slightly displaces when energized and rotates the first stage enlarged part to enlarge and displace the tip of the first stage enlarged part;
a second stage enlarged part that is rotatably provided around a fulcrum, one end of which is connected to the distal end of the first stage enlarged part, and whose other end is enlarged by displacement of the distal end of the first stage enlarged part; In the print head comprising a printing wire attached to the other end of the second stage enlarged portion, the second fulcrum is elastically supported.

[Industrial application field]

The present invention reduces minute displacements of drive elements such as piezoelectric elements when energized by means of a first stage enlarged part that is rotatable around a first fulcrum and a second stage enlarged part that is rotatable around a second fulcrum. This invention relates to a print head that prints by enlarging it in stages.

In recent years, there has been a demand for higher speed printing in print heads for impact printers, but conventional electromagnetic print heads have a limited response speed.

Therefore, print heads using driving elements such as piezoelectric elements with high response speed are being developed. As shown in Nikkei Mechanical, p. 92, published on March 12, 1984, this piezoelectric element is made of a plurality of piezoelectric ceramic green sheets each having a metal paste film formed on one surface to serve as an internal electrode. After laminating, the materials obtained by firing all together are used.

[Conventional technology]

FIG. 3 is a side view showing the structure of a conventional print head of a two-stage displacement enlargement method using this type of drive element. This is an enlarged section.

The first stage enlarged portion 2 is formed by integrally connecting a rigid beam 4 with an elastically deformable support member 5.
The base is fixed to the frame 6. The drive element 1 has a base fixed to the frame 6 and a tip connected to the support member 5, and when energized, it is displaced upward as shown by the arrow, elastically deforming the support member 5, and performing the first stage enlargement. The section 2 is rotated clockwise in the figure about the first fulcrum 7. Second
The stepped enlarged part 3 is a rigid beam-like member, and its base is integrally connected to the tip of the beam 4 by a connecting member 8, and its intermediate part is supported by a second fulcrum 9 fixed to the frame 6. . A printing wire 10 extending downward in the figure is attached to the tip of the second stage enlarged portion 3.

When printing, the drive element 1 is energized for a predetermined period of time.

Due to the upward displacement of the drive element 1 due to this energization, the first stage enlarged part 2 rotates clockwise in the figure around the first fulcrum 7, and this movement causes the second stage enlarged part 2 to rotate the connecting member 8. It is driven through and rotates counterclockwise in the figure around the second fulcrum 90. As a result, the printing wire 10 moves downward as indicated by the arrow, and printing is performed using the printing wire 10. The energization to the driving element 1 is stopped immediately before printing is completed, and the printing wire 10 that has completed printing returns to its original position as the driving element 1 and the enlarged portions 2 and 3 return.

[Problem to be solved by the invention]

However, in this conventional structure, since the second fulcrum 9 on which the second stage enlarged part 3 is supported is fixed to the frame 6, there is a problem that stress concentration occurs in this fixed part due to repulsive force during printing, resulting in damage. was there.

An object of the present invention is to provide a print head that can extend the life of the print head by alleviating the stress applied to the second fulcrum during printing.

[Means to solve the problem]

FIG. 1 is a diagram illustrating the principle of the present invention. In the figure, 11 is a drive element such as a piezoelectric element, 12 is a first stage enlarged part, and 13 is a second stage enlarged part.

The drive element 11 has a base fixed to the frame 17, and is displaced upward as indicated by an arrow when energized.

The first stage enlarged portion 12 is rotatable around the first fulcrum 14 . In this figure, the first stage enlarged portion 12 is constructed by integrally connecting an elastically deformable support member 16 to a rigid beam 15. The base of the support member 16 is fixed to the frame 17, and this fixed portion is the first fulcrum 14.
corresponds to

The tip of the drive element 11 described above is connected to the support member 16.

The second stage enlarged part 13 is rotatably provided around a second fulcrum 18 and has one end connected to the tip of the first stage enlarged part 12,
The displacement of the tip of the first stage enlarged portion 12 causes the other end to be enlarged. This figure shows an example in which one end of the beam-shaped second stage enlarged portion 13 is integrally connected to the tip of the beam 15 by a connecting member 19. A printing wire 20 is attached to the other end of the second stage enlarged portion 13 and extends downward in the figure.

The second fulcrum 18 is elastically supported.

This figure shows an example in which the second fulcrum 18 is provided on a block 21, and the block 21 is supported by the frame 17 via a leaf spring 22.

[For production]

When printing, the drive element 11 is energized for a predetermined period of time. Due to the upward displacement of the drive element 11 due to this energization, the first stage enlarged portion 12 rotates clockwise around the first fulcrum 14.
The second stage enlarged part 13, which has one end connected to the tip of the first stage enlarged part 12, rotates counterclockwise around the second fulcrum 18. Due to this rotation of the second stage enlarged portion 13, the printing wire 20 moves downward, and printing is performed using the printing wire 20. The displacement at the tip of each enlarged portion during these operations is enlarged as follows.

First stage enlarged portion: r 2 / r 1 times Second stage enlarged portion: r 4 / r 3 times In other words, a sufficient amount of displacement is given to the printing wire 20.

The energization to the driving element 11 is stopped immediately before the printing is completed, and the printing wire 20 that has completed printing is connected to the driving element 1.
1. With the return of the first stage enlarged section 12 and second stage enlarged section 13, the original state is restored.

In the conventional structure in which the second fulcrum is fixedly supported during the above-mentioned printing operation, there is a problem that the second fulcrum breaks.
In the present invention, since the second fulcrum 18 is elastically supported, the stress applied to the second fulcrum 18 is relaxed and breakage is prevented. However, if the spring constant of the leaf spring 22 or the like that elastically supports the second fulcrum 18 is too weak, the second stage enlarged portion 13 will not rotate but will move in translation, resulting in an increase in displacement at this portion. Therefore, it is necessary to set the spring constant of the leaf spring 22 to be sufficiently large compared to the spring constant of the support member 16.

〔Example〕

The invention will now be described in detail with reference to FIG.

FIG. 2 (al is a side view showing the structure of the print head according to the present invention, FIG. 2 (bl is a front view of the same, and in the figure, 31 is a cylindrical frame (corresponding to the frame 17 in FIG. 1), 32 is a cover. Note that the same members as in FIG. 1 are given the same reference numerals.

In this embodiment, a plurality of sets of each member except the frame shown in FIG. 1 are provided, and each member of each set includes a cylindrical frame 31
They are arranged at equal intervals in the circumferential direction. In FIG. 2, only one set is shown.

When printing, a desired set of drive elements 11 is energized for a predetermined period of time. As a result, the first stage enlarged part 12 connected to the drive element 11 rotates clockwise in FIG. 2(a), and the second stage enlarged part 13 rotates counterclockwise in FIG. 2 Tal. Then, printing is performed using the printing wire 20 attached to the second stage enlarged portion 13. The energization to the drive element 11 is stopped immediately before the printing is completed, and the printing wire 20 that has completed printing is transferred to the drive element 11, the first stage enlarged part 12, and the second stage enlarged part 1.
3 returns to the original state.

During this printing operation, since the second fulcrum 18 is elastically supported by the leaf spring 22, the stress applied to the second fulcrum 18 is relaxed, and breakage of the second fulcrum, which has been a problem in the past, is prevented. However, if the spring constant of the leaf spring 22 that supports the second fulcrum 18 is too weak, the second stage enlarged part 13 will not rotate but will move in translation, making it impossible to obtain an enlarged displacement in this part. It is necessary to set the spring constant of the temporary spring 22 to be sufficiently large compared to the spring constant of the support member 16.

〔Effect of the invention〕

As described above, according to the present invention, since the second fulcrum is elastically supported by a leaf spring or the like and has a degree of freedom,
Breakage can be prevented by alleviating the stress applied to the second fulcrum, making it possible to extend the service life.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the principle of the present invention, Fig. 2 (a) and (b) are explanatory diagrams of the structure of a print head according to an embodiment of the present invention, and Fig. 3 is a side view showing the structure of a conventional print head. In the figure, 11 is a drive element, 12 is a first stage enlarged part, 13 is a second stage enlarged part, 14 is a first fulcrum, 16 is a support member, 17.31 is a frame, 18 is a second fulcrum, and 19 is a 20 is a printing wire, and 22 is a leaf spring.

Claims (1)

[Claims] First stage enlarged portion (1) rotatable around the first fulcrum (14)
2), a drive element (11) that is slightly displaced when energized and rotates the first stage enlarged part (12) to enlarge and displace the tip of the first stage enlarged part (12); and a second fulcrum (18). ), one end of which is connected to the distal end of the first stage enlarged part (12),
a second stage enlarged part (13) whose other end is enlarged by displacement of the tip of the stage enlarged part (12); and the second stage enlarged part (13).
A print head comprising a printing wire (20) attached to the other end of the print head, characterized in that the second fulcrum (18) is elastically supported.