JPH02155777A - Transforming device of movement of piezoelectric element - Google Patents

Abstract

PURPOSE:To increase the strength of soldering of a tilting body with a tilting arm and thereby to improve durability by soldering the tilting arm in a state that the base end thereof projects from the rear end face of the tilting body. CONSTITUTION:An arm fitting groove 8a is provided in the top face of a tilting body 8 formed integrally with a pair of leaf springs 6 and 7 so that it connects the fore end parts of the springs. A tilting arm 10 is inserted into and soldered to the arm fitting groove 8a of the tilting body 8 so that the base end thereof projects by a prescribed amount W from the rear end face of the tilting body 8. The soldered tilting arm 10 extends in the direction perpendicular substantially to the direction of expansion and contraction of a piezoelectric element 1, and a cut-shaped wire fitting groove 10a is formed in the fore end part of the arm. Since the tilting arm 10 is soldered in the projecting state, fillet parts 31 to 33 due to solder are formed between the top and both front and rear end faces of the tilting body 8 and both plate surfaces of the tilting arm 10. Thereby the soldering strength of the tilting arm 10 is increased positively and separation is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention mainly relates to a motion converting device for a piezoelectric element employed in a print head.

[Prior art 1] Regarding the motion conversion of this type of piezoelectric element, for example, the patent application filed in 1983-14 by the same applicant is
There is one numbered 019.

In this case, as shown in FIG. 8, a pair of root springs 6.7
is bent, and the tilting arm 10 is tilted together with the tilting body 8 connected to the tips of the leaf springs 6 and 7.

At the top of the tilting arm 10, an arm is attached extending from the rear end surface on the side where the leaf spring 6 fixed to the frame 2 is disposed to the front end surface on the side where the leaf spring 7 fixed to the movable element 5 is disposed. The groove 8a is recessed, and the tilting arm 10 is the! The three ends are inserted into the arm mounting groove 88 so as to be substantially flush with the rear end surface of the tilting body 8, and are fixed by brazing.

[Problem to be Solved by the Invention 1] By the way, as mentioned above, the arm mounting groove 8 of the tilting body 8
When the tilting arm 10 is brazed to the tilting arm 10, a fillet portion 31 of the brazing is formed between the top surface and front end surface of the tilting body 8 and the side surface of the tilting arm 10 as shown by diagonal lines in FIG.
．． 32 is generated, and the brazing strength of that portion is ensured.

However, in the above, since the rear end surface of the tilting body 8 and the base end surface of the tilting arm 1o are on the same plane,
In this part, there was almost no fillet portion for brazing, and the brazing strength tended to be insufficient.

Further, the stress caused by the tilting motion of the tilting body 8 and the tilting arm 10 acts intensively on the portions where the brazing strength is weak. Therefore, due to the tilting movement, the brazing between the contact portion of the arm mounting groove 8a of the tilting body 8 and the base end of the tilting arm 10 peels off at a portion, which poses a problem in durability.

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide a piezoelectric element motion conversion device in which the strength of brazing between a tilting body and a tilting arm is increased and the durability is excellent.

[Means for Solving the Problems] In order to achieve the above object, the present invention includes a piezoelectric element that expands and contracts when a voltage is applied, a base that supports one end of the piezoelectric element in the expansion and contraction direction, and a base that supports one end of the piezoelectric element in the expansion and contraction direction. A frame extending along one side, a mover disposed at the other end in the expansion and contraction direction of the piezoelectric element, an extending portion of the frame, and IiJ #
a pair of leaf springs whose base ends are respectively fixed to the J+ element and extend in the direction of expansion and contraction of the piezoelectric element; a tilting body coupled to the tips of the pair of leaf springs; A motion conversion device for a piezoelectric element, comprising: a tilting arm that is tilted together with the tilting body by the deflection of both leaf springs when the piezoelectric element expands and contracts; An arm mounting groove is recessed from the rear end surface on the side where the leaf spring on the frame side is arranged to the front end face on the side where the leaf spring on the movable side is arranged, and the base end of the tilting arm is arranged in the tilting direction. The arm is inserted into the arm mounting groove while protruding from the rear end surface of the body by a predetermined distance, and is fixed by brazing.

[Function] In the piezoelectric element motion conversion device configured as described above, the tilting arm is inserted into the arm mounting groove of the tilting body with the base end of the tilting arm protruding from the rear end surface of the tilting body for a predetermined distance. By brazing, a fillet portion for brazing is formed between the top surface and both front and rear end surfaces of the tilting body and the side surface of the tilting arm.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 to 7.

This embodiment exemplifies the use of a print head, and in FIGS. 3 and 4, the piezoelectric element 1, which expands and contracts when a voltage is applied, is made of laminated piezoelectric ceramic.

The main frame 2 for supporting the piezoelectric element 1 is
The piezoelectric element 1 is made of a metal plate having a predetermined thickness and having a vertically rectangular shape extending substantially parallel to the direction of expansion and contraction of the piezoelectric element 1. At one end of this main frame 2, there is a
A base 3 is provided to protrude in the lateral direction for supporting the lower end (a<lower end) via a temperature compensating material 12, which will be described later.

A movable element 5 is disposed at the other end (upper end) of the piezoelectric element 1 in the expansion/contraction direction, facing the upper end of the rising portion of the main frame 2 . A pair of leaf springs 6 and 7 are fixed to the opposing surfaces of the movable element 5 and the main frame 2 at their base end portions by brazing. Both leaf springs 6° 7 face each other with a predetermined gap in between, and extend a predetermined length from the upper end surfaces of the main frame 2 and the movable member 5 in the direction of expansion and contraction of the piezoelectric cord 1.

A tilting body 8 is provided at each tip end (extending end) of both leaf springs 6 and 7 in a state that is integrally connected to both leaf springs 6 and 7.
is formed.

A subframe 4 is integrally formed at one end of the base 3 of the main frame 2.

The subframe 4 extends along the other side of the piezoelectric element 1 (the side opposite to the main frame 2) to a position facing the movable element 5.

A four-bar parallel link mechanism 16 is provided between the extending end of the subframe 4 and the movable element 5 for guiding the movable element 5 in parallel to the expansion and contraction direction of the pressure element 1 based on the expansion and contraction of the pressure element 1.
is installed. As shown in FIGS. 4 and 6, this parallel link mechanism 16 includes a pair of link plates 17 formed by punching and bending two pieces of elastically deformable leaf spring material. , is mainly composed of a connecting portion 26 that connects both link plates 17 together.

The pair of link plates 17 includes vertical link portions 18.19 parallel to the direction of expansion and contraction of the piezoelectric element 1, and elastically deformable hinge portions 22.23.
24, 25 and horizontal link portions 20, 21, respectively, forming four parallel links. The vertical link portions 18 of each one of the link plates 17 are fixed to both side surfaces of the subframe 4 by spot welding or the like, and the other vertical link portions 19 are fixed to both side surfaces of the movable element 5 by spot welding or the like. is fixed by.

Further, in this embodiment, each one of the vertical link portions 1
A connecting plate 30 is integrally formed at one end of the lower part of the connecting plate 8 . Each of the front two connecting plates 30 extends to the side of the main frame 2. moreover,
Both ends of each connection plate 30 are fixed to the side surfaces of the main frame 2 and subframe 4 by spot welding or the like. This keeps the subframe 4 parallel to the main frame 2 and increases the rigidity of each frame 2.4.

A temperature compensation material 12 is interposed between the base 3 of the main frame 2 and the end surface of the piezoelectric element 1 in a state where a predetermined compressive load is applied to the piezoelectric element 1. The temperature compensation material 12 is made of a material having a positive temperature linear expansion coefficient characteristic opposite to the negative temperature linear expansion coefficient characteristic of the piezoelectric element 1, such as a zinc material or an aluminum material. The expansion and contraction of the piezoelectric element 1 due to changes in ambient temperature is corrected by the vertical expansion of the temperature compensating material 12, so that the top surface of the piezoelectric element 1 is always kept constant.

Note that the mutual contact surfaces between the lower surface of the mover 5 and the other end surface of the piezoelectric element 1 in the expansion/contraction direction, as well as the mutual contact surfaces between the lower surface of the temperature compensating material 12 and the upper surface of the base 3, are bonded with adhesive as necessary. Ru.

As shown in FIGS. 1 and 3, a leaf spring 6 fixed to the main frame 2 is attached to the top surface of the tilting body 8 that is integrally formed across the tips of the pair of leaf springs 6 and 7. An arm mounting groove 88 is recessed from the rear end surface on the side where the movable member 5 is disposed to the front end surface on the side where the leaf spring 7 fixed to the movable element 5 is disposed. Further, the tilting body 8 is cut out in the shape of a notch at both sides of the leaf springs 6 and 7 in the width direction, thereby reducing the weight.

A tilting arm 10 formed of a flat plate material is inserted into the arm mounting groove 8a of the tilting body 8 with its base end protruding from the rear end surface of the tilting body 8 by a predetermined distance ff1W, and is fixed by brazing. ing.

Further, the tilting arm 10 brazed to the arm mounting groove 88 of the tilting body 8 extends in a direction substantially perpendicular to the direction of expansion and contraction of the piezoelectric element 1, and has a cutout-shaped wire attachment at its tip. A groove 10a is formed. The base end portion of the printing wire 11 is inserted into the wire attachment groove 10a and fixed by brazing.

In this embodiment configured as described above, when a voltage is applied between both electrodes of the piezoelectric element 1, the piezoelectric element 1
It extends by a predetermined length in the stacking direction, that is, in the direction of arrow X in FIG. 4, and the movable element 5 is displaced based on this. Then, in response to the displacement force of the movable element 5, the leaf spring 7 on the movable element 5 side is pushed up along the leaf spring 6 on the main frame 2 side. Mover 5
When the leaf spring 7 on the side bends greatly toward the leaf spring 6 on the main frame 2 side, a rotational moment is generated in the direction of arrow P in the tilting body 8, which causes the tilting arm to move integrally with the tilting body 8. 10 is tilted forward. Then, with the printing wire 11 at the tip of the tilting arm 10 being guided by a predetermined number of guide members 15, the tip is advanced to the printing position.

When the voltage application to the piezoelectric element 1 is cut off, the piezoelectric element 1 contracts to its original state, and the movable element 5 is displaced in the opposite direction by the elastic force based on the deflection of both leaf springs 6 and 7. be done. As a result, a rotational moment is generated in the tilting body 8 in the opposite direction, and the tilting arm 1o is tilted backward together with the tilting body 8 to its original position.

Now, since the tilting arm 10 that is brazed to the arm mounting groove 88 of the tilting body 8 is brazed with its base end protruding from the rear end surface of the tilting body by a predetermined MW,
The top surface and both front and rear end surfaces of the tilting body 8 and the tilting arm 10
As shown by diagonal lines in FIGS. 1 and 2, there are fillet portions 31 and 32 formed by front brazing between the screen and the screen surface.
．． 33 is formed. As a result, the strength of the brazing/brazing of the tilting arm 10 to the arm attachment groove 8a of the tilting body 8 is positively increased, and the brazing is prevented from peeling off from the part.

Furthermore, the brazed fillet portion 33 formed between the rear end surface of the tilting body 8 and the base end of the tilting arm 10 connects the upper part of the rear end surface of the tilting body 8 and the base end of the tilting arm 10. The stress acting between them is also reduced, and durability is improved.

As a result of analyzing the stress distribution of the tilting arm 10 using the finite element method, the results shown in FIG.

That is, the one shown in FIG. 7 (sign) shows this embodiment, and the one shown in FIG. 8 shows the prior art in which the tilting arm 10 is brazed to the arm mounting groove 8. However, the plate thickness of the tilting arm 10 and the length L from the rear end surface of the through hole 9 and the tilting body 8 to the tip end surface of the tilting arm 10 are set equal in both this embodiment and the prior art. There is.

Moreover, the waveform line represented on each tilting arm 10 indicates the stress distribution that occurs when a predetermined load (for example, 11 Ky) is applied to the tip of each tilting arm 10, and on the waveform line there is a stress distribution that is proportional to the stress. The numerical value is shown.

Therefore, as is clear from a comparison of Fig. 7 0) and (f), in this embodiment the stress generated near the (l end face of the tilting body 8 is numerical ■) was reduced.

[Effects of the Invention] As described above, according to the present invention, the l of the tilting arm is
By brazing the tilting arm to the arm mounting groove of the tilting body with the end protruding from the rear end surface of the tilting body by a predetermined distance, the top surface of the tilting body and both rear end surfaces of the tilting body and the side surfaces of the tilting arm are connected. A fillet portion for brazing can be formed in between. In particular, the strength of brazing can be increased by the fillet formed between the rear end surface of the tilting body and the side surface of the proximal end of the tilting arm that protrudes from the rear end surface. Stress can also be reduced. As a result, when the tilting body and the tilting arm are brazed together, separation of the parts can be actively prevented, and durability can be improved.

[Brief explanation of the drawing]

Figures 1 to 7 of the drawings show an embodiment of the present invention. Figure 1 is a side view showing the main parts of the motion conversion device, and Figure 2 is a sectional view taken along the line ■-■ in Figure 1. , FIG. 3 is a perspective view showing a motion conversion device of a piezoelectric element applied to a print head, FIG. 4 is a side view, FIG. 5 is a v-vsa sectional view of FIG. 4, and FIG. 6 is a four-section A perspective view showing the parallel link mechanism of , Fig. 70)
1 and 2 are stress distribution diagrams obtained by analyzing the stress distribution of each tilting arm of the embodiment of the present invention and that of the prior art using the finite element method. FIG. 8 is a side view of the prior art. 1...Piezoelectric element 2...Main frame 3...Base 4...Sub frame (frame) 5...Movable element 6.1...Plate spring 8...Tilt body 8a ...Arm mounting groove 10...Tilt arm 31.32.33...Fillet part (frame)

Claims (1)

[Scope of Claims] A piezoelectric element that expands and contracts when a voltage is applied; a frame that has a base that supports one end of the piezoelectric element in the expansion and contraction direction and extends along one side of the piezoelectric element; a movable element disposed at the other end in the expansion/contraction direction; a pair of leaf springs whose base ends are fixed to the extension part of the frame and the movable element, respectively, and extend in the expansion/contraction direction of the piezoelectric element; A piezoelectric device comprising: a tilting body coupled to a tip of a leaf spring; and a tilting arm fixed to the tilting body and tilted integrally with the tilting body by deflection of both leaf springs based on expansion and contraction of the piezoelectric element. In the element motion conversion device, the top surface of the tilting body extends from the rear end surface on the side where the leaf spring on the frame side is disposed to the front end surface on the side where the leaf spring on the movable element side is disposed. An arm mounting groove is recessed, and the tilting arm is inserted into the arm mounting groove and fixed by brazing with its base end protruding from the rear end surface of the tilting body by a predetermined distance. A motion conversion device for piezoelectric elements.