JPH0276272A - Movement conversion device of piezoelectric element - Google Patents

Abstract

PURPOSE:To enable a piezoelectric element to be easily and readily assembled without tentatively holding a both-side plate by adhering the both-side plate to the outer-side surface of a base part while pressing one edge part of the piezoelectric element with a press part of a pilot pressure member. CONSTITUTION:While measuring lifting force of a pilot member 13 by a lifting tool 32 using a load measuring device, the lower surface of a temperature compensated material 12 at one edge in the expansion and contraction of a piezoelectric element 1 is pressed by the pilot member 13. Then, while pressing the other edge surface in the direction of expansion and contraction of the piezoelectric element 1 to the lower surface of a movable element 5, the pilot member 13 is adhered 34 to the outer-side surface of a recessed part of a base part 3 in a both-side plate 13b to allow the mutual opposing surfaces of the base part 3, the pilot member 13, the movable element 5, the piezoelectric element 1, and a temperature compensated material 12 to contact one another without any gap for applying a specified load. It allows the piezoelectric element 1 to be easily assembled without any gap between the base part 3 and the movable element 5 of a frame 2 without tentatively holding the both-side plate.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a motion conversion device for a piezoelectric element used mainly in a print head, and relates to a motion conversion device for a piezoelectric element f assembled between a base of a frame and a movable element. The present invention relates to a motion conversion device for a piezoelectric element in which the amount of displacement of the movable element due to expansion and contraction is magnified in a motion conversion mechanism connected to the movable element.

(Prior art) In this type of piezoelectric element motion conversion device, if a gap occurs between the base of the frame, the movable element, and the piezoelectric element, the displacement of the movable element is insufficient by the amount corresponding to this gap. As a result, the magnification rate of the motion conversion mechanism with respect to the expansion/contraction M of the piezoelectric element decreases.

The amount of expansion and contraction of the piezoelectric element is minute, and in order to accurately transmit this minute amount of expansion and contraction to the motion conversion mechanism through the movable element, it is necessary to place the piezoelectric element in a space between the base of the frame and the movable element. In addition to assembling the piezoelectric element, it is necessary to apply a predetermined compressive load to the piezoelectric element.

For this reason, there is, for example, Japanese Patent Application No. 135375/1982, which has already been filed by the same applicant.

That is, as shown in FIG. 8, the lower end surface of the piezoelectric element (piezoelectric actuator) 4 is fixed to the gap member 20 with adhesive, and the other end of the piezoelectric cable 4 is attached to the movable element (coupling part) 3 with adhesive. When the frame (base member) is fixed
A rod-shaped suppressing member 15 is inserted into an insertion hole 16 provided at the base (bottom) of the press member 1, and the F@ of the press member 15 is brought into contact with the gap member 2. Then, while pressing the lower end of the pressing member 5 by the suppressing means 17, this pressing force is applied to the pressing means 17.
It is measured by a load detection device (not shown) placed near the.

When the pressing force (compressive load) applied to the piezoelectric element 4 by the pressing means 17 via the pressing member 15 and the gap member 2 reaches a predetermined value, this state is maintained, and the pressing member 15 is pressed against the bottom of the frame 1. It is temporarily fixed in the insertion hole 16 with adhesive. Then, after pushing the pressing means 17 through the insertion hole 16,
The piezoelectric cord 4 is assembled by permanently joining the pressing member 15 to the main frame 1 by brazing.

(Problems to be Solved by the Invention) In the above-mentioned configuration, the pressing member 15 inserted into the insertion hole 16 of the frame 1 is pressed by the pressing means 17, and the pressing member 15 is pressed against the frame 1 by the pressing means 17. On the other hand, the pressing member 15 must be temporarily fixed with an adhesive, and after the adhesive has hardened, the pressing means 17 must be removed from the insertion hole 16 and the final joining must be performed by brazing. There was a problem in that it required time and effort.

In addition, in order to assemble the piezoelectric element 4 without temporarily fixing the pressing member 15 to the frame 1 with adhesive,
In a state where the pressing member 15 is press-fitted into the insertion hole 16 of the frame 1, it becomes necessary to push up the pressing member 15 by the pressing means 17.

However, when the pressing member 15 is press-fitted into the insertion hole 16, the frictional force generated between the insertion hole 16 and the pressing member 15 becomes large, and it is necessary to use the pushing-up means 17 with a correspondingly large pushing-up force. Due to variations in the frictional force, problems such as excess or deficiency in the compressive load applied to the piezoelectric element 4 tend to occur.

In view of the above-mentioned problems, it is an object of the present invention to easily assemble a piezoelectric element between the base of a frame and a movable element without any gaps, and to accurately apply a predetermined compressive load to the piezoelectric element. An object of the present invention is to provide a motion converting device for a piezoelectric element that is capable of converting the motion of a piezoelectric element.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides a frame having a base portion supporting one end of the piezoelectric element in the expansion and contraction direction, and a movable frame disposed at the other end of the piezoelectric element in the expansion and contraction direction. A motion converting device comprising a movable element, a motion converting mechanism connected to the movable element to expand the expansion and contraction movement of the pressure rIi element, and a preload member applying a predetermined compressive load to the piezoelectric element, The preload member includes a pressing portion that presses one end side of the piezoelectric element;
The pressing portion is provided with both side plates movable along the outer surface of the base in the compression direction of the piezoelectric element on both sides of the pressing portion and fixed to the outer surface of the base.

(Function) In the piezoelectric element motion conversion device configured as described above, the preload member that applies a predetermined compressive load to the piezoelectric element is moved along the outer surface of the base of the frame on both side plates, and the preload member is moved along the outer surface of the base of the frame. By fixing the both side plates to the outer surface of the base while one end of the piezoelectric element is pressed with a predetermined pressing force by the pressing part of the member, the piezoelectric element can be generated without temporarily fixing the side plates. The elements are assembled.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS. 1 to 6.

This embodiment exemplifies the use of a print head, and in FIGS. 1 and 2, 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 the main frame 2, a base 3 is provided that projects in the lateral direction and supports one end (lower end) of the piezoelectric element 1 in the expansion/contraction direction via a temperature compensating material 12 and a preload member 13, which will be described later. Further, on both side surfaces of the main frame 2, guide grooves 2a for guiding the lead wires 14 of the piezoelectric cable 1 and recesses 2b for weight reduction are formed.

A movable element 5 is disposed at the other end (upper end) of the piezoelectric element 1 in the expansion/contraction direction, facing the -L end of the rising portion of the main frame 2. If a pair of leaf springs 6 and 7 are fixed at one end to the facing surfaces of the movable element 5 and the main frame 2 by brazing, the width of the leaf springs 6 and 7 is equal to that of the main frame 2 and the main frame 2. Each plate spring 6 is formed to be wider than the plate thickness of the mover 5 by a predetermined amount.
Both edges in the width direction of ゜7 are the main frame 2 and mover 5
By brazing the leaf springs 6 and 7 in such a manner that they respectively protrude from the plate thickness plane, the fixing force of each of the leaf springs 6 and 7 to the main frame 2 and the movable element 5 is increased. Further, both the leaf springs 6 and 7 face each other with a predetermined gap in between, and
Piezoelectric element 1 from the upper end surface of main frame 2 and mover 5
It extends a predetermined length in the direction of expansion and contraction. A tilting body 8 is formed at the other end (extending end) of both leaf springs 6.7 and is connected to both leaf springs 6, 7 and -. Further, on the opposite side of the opposing surfaces of both leaf springs 6.7, four parts 5a and 7a are formed in a range extending from the upper end surfaces of the main frame 2 and mover 5 to the lower end of the tilting body 8. The thin-walled portions are each elastically deformable portions 6b.

7b. Furthermore, the plate thickness t2 of the elastically deformable portion 7b of the plate spring 7 fixed to the movable element 5 side is the same as that of the main frame 2.
The elastic strength of the plate spring 7 on the side of the movable element 5 is increased by setting the thickness C to be thicker than the plate thickness t1 of the elastically deformable portion 6b of the plate spring 6 fixed to the side. This actively prevents buckling and breakage of the leaf spring 7 on the movable element 5 side, improving durability.
is planned.

The tilting body 8 has 43 arm mounting grooves 8a recessed in parallel with the arrangement direction of the leaf springs 6 and 7, and the tilting arm 10 is inserted into the arm mounting groove 88 at its base. It is fixed by brazing. A cutout-shaped wire attachment groove 10a is provided at the tip of the tilting arm 10.
is formed, and the base end of the printing wire 11 is inserted into the wire attachment groove 10a and fixed by brazing. Note that the tilting body 8, as shown in FIG.
The portions on both sides of the leaf springs 6 and 7 in the width direction are cut out in the shape of notches, thereby reducing weight. Furthermore, the tilting arm 10 is provided with through holes 9 of appropriate sizes for weight reduction.

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 disposed 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 piezoelectric element 1 based on the expansion and contraction of the piezoelectric element 1. It is set up. As shown in FIG. 4, 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, and both links. The main body is a connecting portion 26 that connects the plates 17 together.

The pair of link plates 17 include vertical link portions 18 and 19 parallel to the direction of expansion and contraction of the piezoelectric element 1, and these two-class links 8 and 19.
I178.19 rl elastically deformable hinge portion 22.
23.24.25 Lateral link section 20.
21 respectively, forming a four-section parallel link. 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, a connecting portion 26 is integrally formed across the tip of each vertical link portion 19 fixed to both side surfaces of the mover 5, and this connecting portion 26 is arranged on the upper end surface of the mover 5 with a predetermined gap therebetween. Ru.

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 connection plates 30 extends to a side surface of the main frame 2. moreover,
Both ends of each connecting plate 30 are fixed to the side surfaces of the main frame 2 and the nub frame 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.

In addition, in this embodiment, in the portion where the link plate 17 and the connecting plate 30 are arranged, the main frame 2. The plate thicknesses of the subframe 4 and mover 5 are reduced, so that the link plate 17 and the connection plate 30 can be assembled within the plate thickness of the main frame 2 and subframe 4, and the device can be miniaturized. There is. Further, in the portions where the hinge portions 22 to 25 and the horizontal link portions 20.21 of the link plate 17 are arranged, the hinge portions and the horizontal link portions are prevented from coming into contact with the side surfaces of the subframe 4. A thin wall portion 4a is formed at the extending end of the nub frame 4.

Now, the piezoelectric element 1 and the temperature compensation material 12 are assembled between the base 3 of the main frame 2 and the movable element 5 in a state where they are preloaded by a predetermined pressure by a preload member 13. As a result, a predetermined compressive load is applied to the piezoelectric element 1 in its expansion and contraction direction.

The preload member 13 includes a flat plate-shaped suppressing part 13a that contacts one end surface of the piezoelectric element 1 and presses the piezoelectric element 1, and a base part that is bent downward at right angles from both ends of the pressing part 13a. The piezoelectric element 1 is formed into an inverted J-shape with both side plates 13b fitted along the outer surface of the piezoelectric element 1 so as to be movable in the direction of expansion and contraction of the piezoelectric element 1.

Further, as shown in FIGS. 5 and 6, both side plates 13
A jig 32 is provided on the lower end surface of b to push up these side plates 13b.
When pushing up using the pusher jig 32, a V-groove-shaped slip stopper groove 13c is formed that engages with the protrusion 33 on the tip surface of the push jig 32 to prevent slippage. Also, in this example,
As shown in FIG. 1, on both outer surfaces of the base 3, there are recesses 3a for guiding the movement of both side plates 13b of the preload member 13 in the compression direction of the piezoelectric element 1 while preventing the side plates 13b from swinging laterally. is formed. Furthermore, when the both side plates 13b of the preload member 13 are pushed up along the recess 3a, in order to reduce as much as possible the frictional force generated on the opposing surfaces of the side U between the both side plates 13b and the recess 3a, A slight gap is set between the side plates 13b and the fourth part 3a.

First, as shown in Figure 6, the main frame 2
After the motion conversion mechanism composed of the leaf springs 6, 7, the tilting body 8, the tilting arm 10, and the printing wire 11 is assembled between the movable element 5 and the movable element 5, a The preload member 13 is fitted so as to be able to move up and down.

Further, a temperature compensating material 12 is fixed in advance to one end surface of the piezoelectric element 1 in the expansion and contraction direction using an adhesive.

Note that adhesive is applied to the upper surface of the pressing portion 13a of the preload member 13, the lower surface of the temperature compensator 12, the lower surface of the movable element 5, or the other end surface of the piezoelectric element 1 in the expansion and contraction direction, as necessary.

Next, as shown in FIG. 5, the lower surface of the temperature compensating material 12 is brought into contact with the upper surface of the pressing part 13a of the preload member 13, and the piezoelectric The other end surface of the element 1 in the expansion/contraction direction is pressed against the lower surface of the movable element 5 with a predetermined load. At this time, the push-up jig 3
2, the pushing up force of the preload member 13 is applied to this pushing up jig 3.
This is carried out while being measured by a load measuring device (not shown) placed near 2.

Then, while a predetermined compressive load is applied to the piezoelectric element 1, both side plates 13b of the preload member 13 are fixed 34 to the outer surface of the recess 3a of the base 3 by spot welding and laser welding. Element 1 is assembled.

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 height of the top surface of the piezoelectric element 1 is always kept constant.

Further, in this embodiment, four cutout-shaped parts 5a are formed at both widthwise edges of the lower part of the movable element 5, and the narrowed portions thereby serve as elastic stretchable parts 5b. Further, the elastic stretchable portion 5b of the movable element 5 is formed by a plate spring 7.
It is formed to have higher rigidity than the elastically deformable portion 7b and to be able to expand and contract slightly elastically in the direction of expansion and contraction of the piezoelectric element 1. A predetermined amount of displacement of the movable element 5 based on the expansion and contraction of the piezoelectric cord 1 is ensured, and when the piezoelectric element 1 contracts when the voltage is cut off to the piezoelectric element 1, the elastic expansion and contraction portion of the movable element 5 is secured. By slightly elongating 5b, the tensile force acting on the piezoelectric element 1 is reduced. Even when the piezoelectric element 1 is made of a piezoelectric ceramic having a property of being fragile against tensile force, the piezoelectric cable 'F1 is prevented from being damaged.

In this embodiment configured as described above, when assembling the piezoelectric cord 1 between the base 3 of the main frame 2 and the mover 5, the preload member 13 is
While measuring the upward slope of the piezoelectric element 1 with a load measuring device, the lower surface of the temperature compensating material 12 at one end of the piezoelectric element 1 in the expansion/contraction direction is pressed by the preload member 13, and the other end surface of the piezoelectric element 1 in the expansion/contraction direction is pressed against the lower surface of the movable element 5. Under pressure contact condition, pre-LE
By fixing 34 the member 13 to the outer surfaces of the four parts 3a of the base 3 on both side plates 13b, the mutually opposing surfaces of the base 3, preload member 13, mover 5, piezoelectric element 1, and temperature compensating material 12 are fixed. It can be brought into contact without any gaps, and
A predetermined load can be accurately applied to the piezoelectric element 1 in its compression direction.

As a result, the movable element 5 can be fully and reliably displaced based on the elongation of the piezoelectric element 1 (elongation in the X direction in FIG. 2) due to the application of voltage. 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, and both leaf springs 6 and 7' are bent into a curved shape. In particular, when the leaf spring 7 on the movable element 5 side is largely bent toward the leaf spring 6 on the main frame 2 side, a rotational moment is generated in the direction of arrow P in FIG. 2, and the tilting body 8 is tilted. Then, with the printing wire r11 at the tip of the tilting body 8 being guided by a predetermined number of guide members 15, the tip is advanced to the printing position.

When the application of voltage to the piezoelectric element 1 is cut off, the piezoelectric element 1 is shortened to its original state. Then, the movable element 5, both leaf springs 6.7, and the tilting body 8 are returned to their original states, and the printing wire 11 is returned to its original position.

In addition, in this embodiment, the base 3 of the C1 main frame 2
Both side plates 13b of the preload member 13 are attached along the four parts 3a provided in the
By guiding the movement of the pressing portion 13a, it is possible to prevent the pressing portion 13a from tilting. For this reason, it is possible to avoid applying the pressing force on one end surface of the piezoelectric element 1 by the pressing part 13a perpendicularly to the compression direction of the piezoelectric element 1, and without applying bending moment or tensile stress to the piezoelectric element 1. A compressive load can be uniformly applied to 1.

Furthermore, a slight gap is set between the recess 3a of the base 3 and the side plates 13b of the preload member 13, and
2 pushes up the preload member 13, so that the frictional force generated between the recess 3a of the base 3 and the side plates 13b of the preload member 13 can be reduced as much as possible. Therefore, it is possible to accurately apply a predetermined compressive load to the piezoelectric element 1 without excess or deficiency.

In addition, in the illustrated embodiment, the preload member 13 and the temperature compensating member 12 are formed separately and assembled together, but the present invention is not limited to this. For example, as shown in FIG. 7, the preload member 13 may be constituted by a pressing portion 13a that also functions as a temperature compensating material, and both side plates 13b provided at both ends of the pressing portion 13a. Furthermore, instead of measuring the pushing up force of the preload member 13, the displacement of the free end of the printing wire 11 may be measured using a displacement measuring device such as a Rade measuring device.

(Effects of the Invention FA) As described above, according to the present invention, the preload member that applies a predetermined compressive load to the piezoelectric element is moved along the outer surface of the base of the main frame on both sides of the preload member. By fixing both side plates to the outer surface of the base while pressing one end of the piezoelectric element with a predetermined pressing force by the pressing part of the preload member, the both side plates can be temporarily attached. It is possible to easily and quickly assemble the piezoelectric element without having to put it all together, and it is also possible to accurately apply a predetermined compressive load to the piezoelectric element.

[Brief explanation of the drawing]

1 to 6 of the drawings show an embodiment of the present invention, in which FIG. 1 is a perspective view showing a motion conversion device of a piezoelectric element acting on a print head, and FIG. 2 is a side view. Figure 3 is a sectional view along the line ■-■ in Figure 2, Figure 4 is a perspective view showing the four-section parallel link mechanism, Figure 5 is a vertical view showing the state in which the piezoelectric element is assembled, and Figure 6 is Similarly, FIG. 7 is a longitudinal sectional view showing a modified example of the member, and FIG. 8 is a sectional view showing a prior art. 1...Piezoelectric element 2...Main frame (frame) 3...Base 5...Movable elements 6, 7...Plate spring 8...Tilt body 13...Preload member 13a ... Pressing part 13b... side Board applicant Brother Industries, Ltd. Patent attorney Hidehiko Okada (3 others) ↑ Figure 5 A1- Figure 7 Figure 8

Claims (1)

[Scope of Claims] A frame having a base that supports one end of the piezoelectric element in the expansion/contraction direction; a movable element disposed at the other end of the piezoelectric element in the expansion/contraction direction; A motion converting device comprising: a motion converting mechanism that expands motion; and a preload member that applies a predetermined compressive load to the piezoelectric element, the preload member including a pressing portion that presses one end side of the piezoelectric element. , characterized in that both side plates are formed on both sides of the pressing part to be movable in the compression direction of the piezoelectric element along the outer surface of the base, and are fixed to the outer surface of the base. Piezoelectric element motion conversion device.