JPH0419946B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a printing element, and particularly to a printing element using a piezoelectric material as a driving source.

2A and 2B are a side view and a partial front view, respectively, of the conventional printing element of FIGS. 1 and 2; FIG.
The piezoelectric body 4 is a driving source for the printing operation, and as shown in a partial cross-section in FIG. It is connected to. Electrodes 41 and 4 through lead 5
When a driving voltage is applied between electrodes 43 and 4,
When the driving voltage is applied between the piezoelectric elements 4 and 4, due to the electrostrictive effect, the width of the piezoelectric body 4 decreases as shown by broken line arrows D and E, and the length increases as shown by broken line arrow F, thereby generating dimensional distortion. Both ends of the piezoelectric body 4 (second
A protective layer 45 made of a piezoelectric material is provided (only the upper end is shown in the figure), and both ends of the piezoelectric body 4 are bonded to the metal connecting members 2 and 3 with an adhesive 12, respectively. The connecting member 2 is connected to the bottom of the metal base member 1 via a plate-like member,
Further, the connecting member 3 is connected to the lower ends of metal movable members 6 and 7 via two plate-like members. The lower ends of the movable members 6 and 7 are also connected to the upper end of the base member 1 via plate-shaped members, and one ends of the transmission members 8 and 9 made of plate-shaped metal are fixed to the tips of the movable members 6 and 7, respectively. It has been done. The other ends of the transmission members 8 and 9 are fixed to the end of a metal movable member 10, and a metal wire 11 for printing is attached to a predetermined location of the movable member 10.

When a driving voltage is applied, the connecting member 3 is pushed up towards the information as shown by the broken line arrow F due to the dimensional distortion occurring in the piezoelectric body 4, and along with this, the movable members 6 and 7
An angular displacement occurs at each tip in the directions indicated by dashed arrows A and B, respectively. This angular displacement is transmitted to the movable member 10 via the transmission members 8 and 9 to generate a rotational motion, giving the wire 11 a motion in the direction indicated by the dashed arrow C to perform dot printing.

In such a conventional printing unit, a piezoelectric material 4 is used.
The disadvantage is that the adhesive 12 that joins both ends of the connector and the connecting members 2 and 3 is likely to peel off during operation, causing problems. That is, when the drive voltage is applied, the piezoelectric material between the electrodes 43 and 44 shrinks in width and increases in length as described above, so bending stress acts on the protective layer 45 bonded thereto. Therefore, in the adhesive 13 that joins the protective layer 45 and the connecting member 3 (or 2), tensile stress acts on the peripheral portion and compressive stress acts on the central portion. Usually, the tensile stress acting on the adhesive 12, especially in the peripheral area, is quite large, so that during repeated operations, the adhesive 12 develops cracks that spread and cause adhesive peeling. If the adhesive peels off, the dimensional strain occurring in the piezoelectric body 4 will not be transmitted smoothly, resulting in problems such as a significant drop in printing pressure.

SUMMARY OF THE INVENTION An object of the present invention is to provide a printing element that eliminates the above-mentioned drawbacks, reduces the tensile stress acting on the joints at both ends of the piezoelectric body, and prevents problems due to adhesive peeling.

The present invention provides a columnar drive member having a piezoelectric material that generates dimensional distortion in response to a printed drive voltage;
In the printing element, the printing element includes a displacement transmission mechanism that generates a displacement in response to the dimensional strain transmitted from a joint with the driving member and transmits the displacement to a printing wire member, wherein the driving member includes a plurality of the Piezoelectric bodies are bonded together to form a columnar shape, and 4 points near the bonded point
A connecting member covering in a band shape is joined to at least two side faces facing each other out of the two side faces and at least two side faces facing each other out of the four side faces near the end face joined to the displacement transmission mechanism. characterized by something.

Next, the present invention will be explained in detail with reference to the drawings.

FIG. 3 is a partial side view showing the first embodiment of the present invention. In this embodiment, a case is shown in which two piezoelectric bodies 46 and 47 bonded together are used as the piezoelectric body 4 in FIG. 1. Conventionally, in such cases, the end surfaces of the two piezoelectric bodies are directly bonded using an adhesive, but during operation, the two protective layers bonded to each other undergo bending deformation in opposite directions.
Excessive stress acts on the adhesive at the joint, which tends to cause the adhesive to peel off. In this embodiment, two piezoelectric bodies 46
A connecting member 25 is interposed between the joints 47 and 47 to join them together. The connecting member 25 is a member having recesses on both sides of a metal plate into which the ends of the piezoelectric bodies 46 and 47 are respectively fitted, and the protrusions on both sides of the recesses allow the piezoelectric bodies 46 and 47 to fit together when the piezoelectric bodies 46 and 47 are fitted. It is formed so as to cover the two opposing sides of the ends of and 47. The piezoelectric bodies 46 and 47 and the connecting member 25 are bonded with adhesives 15 and 16, respectively. Since they are connected via the connecting member 25 in this way,
As will be described later, bending deformation of the protective layer at the ends of the piezoelectric bodies 46 and 47 during operation is suppressed, and the adhesive 15
and 16 can be reduced to prevent adhesive peeling.

The connecting members 22 and 23, which are joined to both the upper and lower ends of the joined piezoelectric bodies 46 and 47, are also provided with recesses into which the ends of the piezoelectric bodies 46 and 47 are fitted, respectively. The protrusions on both sides of this recess are the piezoelectric body 4
6 and 47 are formed so as to cover the two opposing sides of the ends of the piezoelectric bodies 46 and 47 when inserted. An adhesive 12 is applied between the connecting members 22 and 23 and the piezoelectric bodies 46 and 47, respectively.
and 13. In this way, not only the end faces of the piezoelectric bodies 46 and 47 but also the connecting member 22
And the parts covered by both side protrusions of 23 are also covered with adhesive 1.
2 and 13, the bending deformation of the protective layer 45 during operation can be suppressed, as will be described later, and the stress acting on the adhesives 12 and 13 can be reduced.

FIG. 4 is a characteristic diagram showing an example of the magnitude of stress acting on the adhesive 12 (or 13, 15, 16) in this embodiment. The horizontal axis of the figure is adhesive material 1
2 shows the horizontal position, and the vertical axis shows the acting stress at the angular position. Since the shape is symmetrical as shown in Fig. 3, the characteristics from the center 0 to the right end R, and the characteristics from the center 0 to the left end L, is symmetrical. Also solid line 21
shows the characteristics of this embodiment, and for comparison, the characteristics of the conventional element are shown by a broken line 21. Comparing the tensile stress at the right end R (or left end L) for both characteristics, for example, the conventional element has a tensile stress of about 130 Kg/cm ² and this example has a tensile stress of about 30 Kg/cm ²
, and the effect of stress reduction is remarkable.

In this way, in this embodiment, the adhesives 12, 13,
The tensile stress acting on 15 and 16 is significantly reduced compared to the conventional case, and problems caused by adhesive peeling can be prevented.

FIG. 5 is a partial side view showing a second embodiment of the invention. In this embodiment, the piezoelectric body 46 and the connecting member 3
The piezoelectric body 46 and the connecting member 3 are bonded using an adhesive 12 by providing a metal belt 24 that covers the joint portion with the piezoelectric body 46 and the four side surfaces in the vicinity thereof. Since the four side surfaces of the end of the protective layer 45 of the piezoelectric body 4 are held down by the belt 24 via the adhesive 12, the bending deformation of the protective layer 45 during operation is sufficiently suppressed and acts on the adhesive 12. It can reduce stress.

Note that the connecting member 2 of the first embodiment (see Fig. 3)
5, the end faces of the piezoelectric bodies 46 and 47 may be directly joined with a connecting material, and the belt 24 of the second embodiment (FIG. 5) may be joined around the joint with an adhesive, and the same effect can be obtained. The effect of this can be obtained. Of course,
By similarly using the belt 24 at both the upper and lower ends of the connected piezoelectric bodies 46 and 47, bending deformation of the protective layer at the ends can be suppressed.

In the embodiments listed above, the part of the mechanism that transmits the displacement generated in response to the dimensional strain generated in the piezoelectric body to the wire is the same as the unit shown in FIG. 1, but there is no need to limit it to this. do not have.

As is clear from the above description, the present invention has the effect of reducing the tensile stress acting on the joints at both ends of the piezoelectric body, thereby making it possible to realize a printing element that prevents defects due to adhesive peeling.

[Brief explanation of drawings]

1 and 2 are a side view and a partial front view showing respective conventional printing elements, FIGS. 3 and 5 are partial side views showing an embodiment of the present invention, and FIG. 4 is a partial front view showing an embodiment of the present invention. It is a characteristic diagram for explaining an example. 1... Base member, 2, 3, 22, 25... Connection member, 4, 46, 47... Piezoelectric body, 5... Lead, 6, 7, 10... Movable member, 8, 9... Transmission member , 11... wire, 12, 13. 15, 16
... Adhesive material, 24 ... Belt, 41-44 ... Electrode, 45 ... Protective layer.

Claims (1)

[Scope of Claims] 1. A columnar drive member having a piezoelectric material that generates dimensional distortion in response to a printed drive voltage, and a columnar drive member that is displaced in response to the dimensional distortion transmitted from a joint with the drive member. The printing element includes a displacement transmission mechanism that generates a displacement and transmits it to a printing wire member, wherein the driving member is formed into a columnar shape by joining a plurality of the piezoelectric bodies, and the driving member has a displacement transmission mechanism that generates a displacement and transmits it to a printing wire member.
A connecting member covering in a band shape is joined to at least two side faces facing each other out of the two side faces and at least two side faces facing each other out of the four side faces near the end face joined to the displacement transmission mechanism. A printing element characterized by: