JPH0392361A - Motion convertor of piezoelectric element - Google Patents

Abstract

PURPOSE:To prevent breaking of a piezoelectric element by decreasing bending moment to be given to the piezoelectric element by inclining motion with a movable piece which transmits drive of the piezoelectric element to a motion converting mechanism by a method wherein a contact width of opposed surfaces of a non-bonded part is made less than an abutted width of the opposed surfaces. CONSTITUTION:By elastic deformation of a parallel linking mechanism 16 based on displacement of a movable piece 5, the movable piece 5 is displaced parallel to an elongation and contraction direction of a piezoelectric element 1. However, if the movable piece 5 is considered to be guided with the parallel linking mechanism 16, since it is not accurately moved parallel to a vertical direction and it is moved being slightly inclined, shifting motion of the movable piece 5 is transmitted to the piezoelectric element 1, and bending moment acts on the piezoelectric element 1. In that case, a contact width (a) of an opposed surface of an upper side plate 31 is made less than an abutted width (d) of the opposed surface and thereby, the inclining motion of the movable piece 5 comes difficult to be transmitted to the piezoelectric element 1. Then, bending moment to be given to the piezoelectric element 1 is decreased and consequently, the piezoelectric element is prevented from being broken.

Description

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

[Prior Art] Conventionally, as this type of motion conversion device, there is, for example, Japanese Patent Application No. 63-206539 (unpublished at the time of filing of this application) previously proposed by the same applicant.

As shown in a side view in FIG. 10, this motion converting device includes a piezoelectric element 1 that expands and contracts when a voltage is applied, and a frame (main frame 2) that has a base 3 that supports one end of the piezoelectric element 1 in the expansion and contraction direction. , a movable element 5 disposed at the other end of the piezoelectric element 1 in the direction of expansion and contraction, and a motion converting mechanism connected to the movable element 5 to expand the stretching movement of the piezoelectric thread 1. This motion conversion mechanism is mainly composed of a pair of leaf springs 6.7 having one end fixed to the main frame 2 and the movable element 5, and a tilting body 8 connecting the other end of the leaf spring 6.7. The expansion and contraction of the piezoelectric element 1 due to the application of voltage and the application of the voltage are caused by the plate spring 6.7.
The deflection is converted into a tilting motion of the tilting body 8.

As shown in FIG. 11, which is an enlarged view of the vicinity of the upper end of the piezoelectric element 1, a ceramic plate 31 is coupled to the movable element 5 on the opposing surfaces of the piezoelectric element 1 and the movable element 5, and the piezoelectric element 1
A ceramic plate 32 is coupled to the plate 31, and a non-coupled portion 33 is provided between the plates 31 and 32. That is, piezoelectric element 1
The movable member 5 and the movable member 5 are not connected to each other, but are abutted to each other via plates 31 and 32 so as to be separable. The contact between the plates 31 and 32 is a full-surface contact in which the entire opposing surfaces thereof are in surface contact.

[Problems to be Solved by the Invention] In the above-described motion converting device, when the voltage application to the piezoelectric element 1 is cut off and the piezo Ti cord 1 starts to contract, the mover 5 and the II8 body 8 are still piezoelectric due to inertia. Element 1
The mover 5 is moving in the direction of extension, and its return is delayed, causing the mover 5 to move in the direction of extension.
and the piezoelectric element 1 is separated. Therefore, no tensile force is applied to the piezoelectric element 1, and the piezoelectric cord 1 due to the tensile force
damage is prevented.

However, the movable element 5 does not exactly move in parallel in the vertical direction in the figure, but moves while tilting (this is referred to as a tilting motion).

Therefore, the tilting motion of the movable element 5 is transmitted to the piezoelectric element 1, and a bending moment acts on the piezoelectric element 1.
There remained a problem that the piezoelectric element 1 would break, that is, so-called piezoelectric element breakage.

The present invention has been made to solve the above-mentioned problems, and its purpose is to reduce the bending moment exerted on the piezoelectric element by the movable element that transmits the drive of the piezoelectric element to the motion conversion mechanism due to its tilting movement. The object of the present invention is to provide a motion conversion device for a piezoelectric element that can prevent the piezoelectric element from breaking, thereby improving the durability of the device.

[Means for Solving the Problems] In order to achieve this object, the piezoelectric element motion converting device of the present invention includes: a piezoelectric element that expands and contracts when a voltage is applied; and a base that supports one end of the piezoelectric element in the expansion and contraction direction. A motion conversion device for a piezoelectric element, comprising: a frame; a movable element disposed at the other end of the piezoelectric element in the expansion and contraction direction; and a motion conversion mechanism connected to the movable element to expand the expansion and contraction movement of the piezoelectric element. The device includes a non-coupling portion that can be brought into and out of contact with at least one of the opposing surfaces between the piezoelectric element and the base, or the opposing surfaces between the piezoelectric element and the movable element, and the displacement of the motion conversion mechanism. At least in the direction of tilting of the movable element, the width of contact on the opposing surface of the non-coupled portion is made smaller than the width of the opposing surface.

[Function] According to the motion converting device for a piezoelectric element of the present invention having the above-described configuration, the contact in the tilting direction of the movable element on the opposing surface is reduced, compared to the conventional method in which the opposing surface in the non-coupled portion is in full contact with the piezoelectric element. Area is reduced. As a result, the tilting motion of the movable element is less likely to be transmitted to the piezoelectric element, and the bending moment applied to the piezoelectric element is reduced.

[Example] [First Example] A first example embodying the present invention will be described with reference to FIGS. 1 to 3. For convenience of explanation, parts that are the same as or equivalent to those of the conventional example are given the same reference numerals.

In FIG. 1 showing a side view of the motion conversion device, the motion conversion device includes a frame 80, a piezoelectric element 1, a motion conversion mechanism, and the like.

The piezoelectric element 1 is a laminated piezoelectric element made of laminated piezoelectric ceramic, and expands and contracts in the longitudinal direction (in the vertical direction in the figure) by applying a voltage and cutting off the application.

The frame 80 supporting the piezoelectric element 1 is made of gold JFK (for example, a sintered alloy) and has a substantially U-shape.

This frame 80 includes a main frame section 2 extending parallel to the direction of expansion and contraction of the piezoelectric element 1, and a main frame section 2 extending parallel to the direction of expansion and contraction of the piezoelectric element 1.
It has a base 3 that projects from the lower end of the piezoelectric element 1 and supports the lower end of the piezoelectric element 1 in the expansion and contraction direction, and a subframe 4 that is connected to the base 3 and parallel to the main frame 2. There is.

A movable element 5 is disposed at the other end (upper end in the figure) of the piezoelectric element 1 in the expansion and contraction direction, facing the upper end of the main frame section 2 .

A pair of leaf springs 6 and 7 are each fixed at one end to opposing surfaces of the main frame portion 2 and the movable element 5. Both leaf springs 6.7 face each other with a predetermined gap in between, and their other ends (extending ends) are connected by a tilting body 8. On the top surface of the shift leave 8, there is a wire 1 printed at the tip.
1 is attached to the tilting arm 10 is fixed. The leaf spring 6.7 and the tilting body 8 constitute an Eden spring 67 which causes the tilting body 8 to tilt by displacing the other end of one of the leaf springs 7 along the surface direction of the leaf spring 6. has been done. The Eden spring 67, the movable element 5 and the tilting arm 10 constitute a motion conversion mechanism.

The piezoelectric element 1 is assembled between the base 3 of the frame 80 and the movable element 5 via wedge-shaped temperature compensation members 12 and 13.

Thus, the facing surfaces of the piezoelectric element 1 and the base 3 of the frame 80 (specifically, the temperature compensating material 12 fixed to the base 3) are bonded with an adhesive. On the other hand, piezoelectric element 1 and mover 5
A non-coupled 8Il33 that can be moved into and out of contact with is provided on the opposite surface.

In FIG. 2 showing an enlarged view of the non-bonded portion, the non-bonded portion 33 includes a pair of upper and lower ceramic plates 31.3 made of a material with excellent wear resistance, for example, zirconia ceramic.
2 is provided.

The upper plate 31 is bonded to the mover 5 with adhesive, and the lower plate 32 is bonded to the piezoelectric element 1 with adhesive, and the opposing surfaces of the drawing plates 31, 32 are riil Ii! Possibly abutted. Note that the facing surfaces of the piezoelectric element 1 and the movable element 5 have substantially the same rectangular shape, and the plates 31 and 32 are formed in the shape of a substantially rectangular flat plate larger than the facing surface of the movable element 1. .

Moreover, the piezoelectric element 1, the movable element 5, and the plates 31 and 32 are arranged on the same axis.

In FIG. 3, which shows a perspective view of the facing surfaces of the plates 31, 32, the facing surfaces of the lower plate 32 are flat over the entire surface. On the other hand, a band-shaped protrusion 34 is formed on the opposing surface of the upper plate 31 in a direction intersecting the tilting direction (left-right direction in FIG. 1) of the movable element 5 as the motion conversion mechanism is displaced. Therefore, the contact width a of the movable element 5 in the tilting direction is smaller than the width b of the opposing surface (
(See Figure 2). The distal end surface of the protrusion 34 is a flat surface that comes into contact with the opposing surface of the lower plate 32.

Note that when assembling the piezoelectric element 1 to the frame 80, the upper plate 31 is bonded to the movable element 5 with adhesive;
An upper temperature compensating material 12 and a lower plate 32 are respectively bonded to the piezoelectric element 1 with an adhesive. Thereafter, the pressure N element 1 is inserted between the base 3 and the movable element 5. Then, by lifting the piezoelectric element 1 and inserting the lower temperature compensating material 13 between the base 3 and the upper temperature compensating material 12, a predetermined preload is applied to the piezoelectric element 1. Since the lower temperature compensating material 13 of the bamboo has adhesive applied to its upper and lower surfaces in advance, the base 3 and the upper temperature compensating material 12 are bonded by the insertion.
is combined with

Further, between the upper end of the sub-frame portion 4 and the movable element 5, a four-bar parallel link mechanism made of a spring plate is provided to move the movable element 5 in parallel to the direction of expansion and contraction based on the expansion and contraction of the piezoelectric element 1. 16 are arranged.

Further, a stopper 35 is attached to the upper end surface of the subframe portion 4 for supporting the tilting arm 10 in a standby position.

In the piezoelectric element motion conversion device described above, the piezoelectric element 1
When a voltage is applied to the piezoelectric element 1, the piezoelectric element 1 expands, and the mover 5 is displaced (raised) based on this. As the Eden spring 67 bends in response to the displacement force of the mover 5,
The tilting arm 10 is tilted counterclockwise in FIG. This tilting of the tilting arm 10 causes the printing wire 11 to
is advanced to the printing position.

Furthermore, when the application of voltage to the piezoelectric element 1 is cut off, the piezoelectric element 1 is shortened to its original state. Then, mover 5
and Eden spring 67 returns to its original state,
The printing wire 11 is returned to the standby position. At this time, the tilting arm 10 comes into contact with the stopper 35 and is supported at the standby position.

Also, based on the displacement of the movable element 5, the parallel link mechanism 16
By elastically deforming, the movable element 5 is displaced in parallel to the direction of expansion and contraction of the piezoelectric cord 1.

During the drive of the piezoelectric cord 1, especially at the timing when a simple tensile force is applied to the piezoelectric element 1, that is, at the timing when the piezoelectric M element 1 contracts, the movable element 5, the Eden spring 67,
If the return of the movable element 5 is delayed due to the inertia force based on each quality of the tilting arm 10 and the printing wire 11, the piezoelectric element 1 is not subjected to the above-mentioned tensile force. Therefore, damage to the piezoelectric element 1 due to the tensile force is prevented.

However, even if the movable element 5 is guided by the parallel link mechanism 16, it does not move accurately in parallel in the vertical direction in FIG. 1, but moves while slightly tilting (this is called a tilting movement). The tilting motion of the movable element 5 is transmitted to the piezoelectric element 1, and a bending moment acts on the piezoelectric element 1.

By the way, by making the contact width a of the opposing surface of the upper plate 31 smaller than the corresponding width b of the opposing surface, the contact area in the tilting direction of the mover 5 on the opposing surface is reduced compared to the case where the entire surface contacts. There is.

This makes it difficult for the tilting motion of the mover 5 to be transmitted to the piezoelectric cord 1, and the bending moment applied to the piezoelectric element 1 is reduced, thereby preventing the piezoelectric element from breaking. Therefore, the durability of the motion conversion device is improved, and a dot print head of stable quality can be obtained.

[Second Embodiment] Next, a second embodiment of the present invention is shown in FIG. 4(a). This will be explained with reference to ＜口）. Note that this example is a partial modification of the first example, so only the different configuration will be described in detail, and the first example will be described in detail.
The same parts or equivalent parts as in the example are given the same reference numerals, and their explanation will be omitted. (Hereinafter, the same applies to each embodiment.) In the wooden example, the arrangement of the pair of upper and lower plates 31 and 32 in the first embodiment is reversed. Specifically, a plate 31 having a protrusion 34 is fixed to the piezoelectric cord 1, and the other plate 32 is fixed to the movable element 5.

The same effect as the first embodiment can be obtained using the tree example.

(Third Embodiment) Next, a third embodiment of the present invention will be explained with reference to FIGS.
1 is a pair of upper and lower plates that are fixed vertically symmetrically.

The same effect as the first embodiment can be obtained using the tree example.

[Fourth Embodiment] Next, a fourth embodiment of the present invention will be described with reference to FIGS. In this example, the upper plate 3 in the first embodiment is
1 is replaced with a plate 31A.

The plate 31A has a protrusion 34A having a mountain-shaped cross section formed on its opposing surface in a direction intersecting the direction of tilting of the movable element 5 due to displacement of the motion conversion mechanism.

As a result, the opposing surface of the upper plate 31A is brought into line contact with the opposing surface of the lower plate 32.

This example also provides the same effects as the first example. Furthermore, according to this example, since both plates 31A and 32 are in line contact, the bending moment applied to the piezoelectric element 1 by the movable element 5 due to its tilting movement can be made smaller than in the first example.

[Fifth Embodiment] Next, a fifth embodiment of the present invention will be described with reference to FIG. 7(A). In this example, a pair of upper and lower plates 31A. , 32 are arranged in reverse.

Specifically, a plate 31A having a protrusion 34A is fixed to the piezoelectric element 1, and the other plate 32 is fixed to the movable element 5.

According to this example, the same effects as in the fourth example can be obtained.

[Sixth Embodiment] Next, a sixth embodiment of the present invention will be described with reference to FIGS. In this example, the lower plate 31A of the fifth example is replaced with a plate 31B.

The plate 31B has a square pyramid-shaped protrusion 34B formed on its opposing surface. As a result, the opposing surface of the lower plate 31B is brought into point contact with the upper plate 32.

This example also provides the same effects as the fifth example. Roughly speaking, according to this example, since the drawing boards 31B and 32 are in line contact, the piezoelectric element 1 is bent by the movement in the direction intersecting the tilting direction of the movable element 5 (the front and back directions in FIG. 12). The moment can be reduced, and the piezoelectric element can be prevented from breaking due to the moment.

[Seventh Embodiment] Next, a seventh embodiment of the present invention is shown in FIG. 9(A). This is explained with reference to This example is based on the plate 31.3 in the first embodiment.
2 on board 31C. This is a replacement for 32C. Plate 31C,
32C is formed into a flat plate having the same shape and having a substantially square shape smaller than the square of the opposing surface of the piezoelectric element 1.

This example also provides the same effects as the first example. Further, according to this example, the contact area of the uncoupled portion 33 in the direction intersecting the tilting direction of the movable element 5 (the front and back directions of the sheet in FIG. 14) is also reduced compared to the case where the entire surface is in contact. By the movement in the direction crossing the tilting direction, the bending moment applied to the piezoelectric element 1 can also be reduced, and the piezoelectric element can be prevented from breaking due to this.

Furthermore, the present invention is not limited to the above embodiments,
Changes can be made within the scope of the invention.

For example, the non-coupling portion 33 may be provided on the facing surface of the piezoelectric element 1 and the base 3, specifically, on the facing surface of the piezoelectric element 1 and the upper temperature compensating material 12.

[Effects of the Invention] As is clear from the detailed description above, according to the piezoelectric element motion converting device of the present invention, the movable element that transmits the drive of the piezoelectric element to the motion converting mechanism moves the piezoelectric element through its tilting motion. The bending moment applied can be made smaller than before, which prevents the piezoelectric element from breaking.
Therefore, the durability of the device can be improved.

[Brief explanation of drawings]

1 to 3 show a first embodiment of the present invention, in which FIG. 1 is a side view of a piezoelectric element motion conversion device, FIG. 2 is an enlarged view of a non-coupled portion, and FIG. 3 is a non-coupled portion. FIG. 4 to 9 respectively show the second to seventh embodiments of the present invention, each figure (A) is a side view of the non-bonding part, and the figure (opening) is a perspective view of the opposing surface of the non-bonding part. It is. 10 and 11 show a conventional example, in which FIG. 10 is a side view of a piezoelectric element motion conversion device, and FIG. 11 is an enlarged view of a non-coupled portion. 1... Piezoelectric element 3... Base 5... Mover 33... Uncoupled part 80... Frame

Claims (1)

[Claims] A piezoelectric element that expands and contracts when a voltage is applied; a frame having a base that supports one end of the piezoelectric element in the expansion and contraction direction; and a movable element disposed at the other end of the piezoelectric element in the expansion and contraction direction. A motion converting device for a piezoelectric element, comprising: a motion converting mechanism connected to the movable element and magnifying the expansion and contraction movement of the piezoelectric element, the piezoelectric element and the base facing each other, or the piezoelectric element and the movable element facing each other. A non-coupling portion that can be brought into contact with and separating from at least one of the opposing surfaces of the non-coupling portion is provided, and a contact width on the opposing surface of the non-coupling portion is provided at least in a tilting direction of the movable element due to displacement of the motion conversion mechanism. A motion conversion device for a piezoelectric element, characterized in that: is smaller than the width of the opposing surface.