JPH0239948A - Motion converting device of piezoelectric element - Google Patents

Abstract

PURPOSE:To reduce the vibration of a tilting arm or both leaf springs as low as possible, to increase the tilting motion speed of the tilting arm and to enhance the durability of said arm by a method wherein the tilting arm is brought into contact with the first stopper part on the rear side near to the leading end thereof and the bending of the leaf spring on the side of a movable element is prescribed by the second stopper part. CONSTITUTION:Both leaf springs 6, 7 are displaced in the extending direction of a tilting arm 10 to reach the original position and, thereafter, the leaf spring 7 on the side of a movable element 5 is ready to bend in the extending direction. Whereupon, a tilting body 8 is brought into contact with the stopper part 38 of the second stopper member 37 and the bending of the leaf spring 7 on the side of the movable element 5 is prescribed. Therefore, the vibration of both leaf springs 6, 7 in the directions shown by arrows Q, P is reduced as low as possible and the buckling or breakage of both leaf springs 6, 7 is prevented to enhance the durability of the tilting arm. Further, when the tilting arm 10 is tilted to the original position on the basis of the elastic forces of both leaf springs 6, 7, the rear near to the leading end of the tilting arm 10 is brought into contact with the stopper part 36 of the first stopper member 35 to prevent the tilting arm 10 from further tilting and the bending of the leading end part thereof is prevented as low as possible.

Description

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

(Prior Art) As a motion converting device for piezoelectric elements, for example, there is a patent application No. 62-26849 developed by the same applicant.
No. 6, Japanese Patent Application No. 62-277169, etc.

Further, as shown in FIG. 9, such a piezoelectric element motion conversion device displaces the movable element 5 based on the expansion and contraction of the piezoelectric element 1, and one end of the frame 2 and the movable element 5 are fixed to each other. By bending the pair of leaf springs 6.7, the tilting arm 10 whose base end is connected to the round ends of both leaf springs 6.7 is tilted.

In the motion converting device configured as described above, when the voltage application to the piezoelectric element 1 is cut off and the piezoelectric element 1 is contracted to its original state, both leaf springs 6°7 and the tilting member 7-1
0 returns. At this time, the tilting arm 10 tends to move back further than the rest position due to inertia, and both leaf springs 6,
7 is stopped at its original position while vibrating in the directions of arrows P and Q in FIG. 9 due to the repulsive force caused by the deflection. For this reason, the distance FJ1 required for both leaf springs 6 and 7 to stop at their original positions ff, lJ becomes longer, and the high-speed tilting movement of the tilting arm 10 due to repeated expansion and contraction of the piezoelectric cable 1, for example, increases the speed of printing. Difficult to deal with. However, due to the vibration, the elastic fatigue of both leaf springs 6 and 7 becomes significant, causing a problem in durability.

Therefore, as shown in FIG. 9, the same applicant has proposed that a stopper member 35' be disposed approximately in the longitudinal center of the tilting arm 10 on the n-plane side.

(Problem to be Solved by the Invention) By the way, in the device in which the tilting movement of the tilting arm 40 is restricted by bringing the center portion of the rear side path of the tilting arm 10 into contact with the stopper member 35', the tilting arm 10 is brought into contact with the stopper member 35'.
', the collision force causes the tip of the tilting arm 10 to bend as shown by the chain line in FIG. 7 is vibrated in the directions of arrows P and Q in FIG.
A problem occurs in which vibration occurs in the directions of arrows A and B in the figure.

In view of the above-mentioned problems, an object of the present invention is to reduce the vibration of the tilting arm and the vibrations of both leaf springs as much as possible, thereby increasing the speed of the tilting movement of the tilting arm and improving the durability. It is an object of the present invention to provide a piezoelectric element conversion device that can be used.

(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 main frame extending along the main frame; a movable element disposed at the other end of the piezoelectric element in the expansion/contraction direction; and one end fixed to the extension part of the main frame and the movable element, respectively. a pair of leaf springs extending in the direction of expansion and contraction of the piezoelectric element; a tilting arm that is tilted by the deflection of both leaf springs based on the above, and a first stopper member that has a stopper portion that is removably abutted on the back side of the tilting arm near the tip thereof, and that restricts the deflection of the tilting arm. and a second stopper member having a stopper portion that restricts the bending of the leaf spring on the movable element side in the extending direction of the tilting arm.

(Function) In the piezoelectric element motion conversion device configured as described above, when the piezoelectric element is expanded by application of a voltage, the movable element is displaced based on the expansion.

Then, in response to the displacement force of the movable element, the leaf spring on the movable element side is pushed up along the leaf spring on the main frame side, and both of these leaf springs are bent, and the leaf spring on the movable element side is pushed up on the main frame side. The large deflection toward the leaf spring generates a rotational moment at the base end of the tilting arm connected to the other ends of both leaf springs, thereby causing the tilting arm to tilt.

When the application of voltage to the piezoelectric element is cut off and the piezoelectric element contracts to its original state, both the leaf springs are caused to move in the direction opposite to the direction in which the tilting arm extends due to the elastic force based on the deflection. Displaced. As a result, a rotational moment in the opposite direction to that described above is generated at the base end of the tilting arm, and the tilting arm is tilted toward its original position.

After both the leaf springs are displaced in the direction in which the tilting arm extends and reach their original positions, the leaf spring on the mover side, in particular, tries to bend in the direction in which the tilting arm extends. Then,
Since the deflection of the leaf spring is regulated by the stopper portion of the second stopper member, vibrations of both leaf springs are reduced as much as possible.

Further, when the tilting arm is tilted to the original position, the rear side of the tilting arm near the tip comes into contact with the stopper portion of the first stopper member, thereby preventing further tilting of the tilting arm. Further, as described above, the second stopper prevents the leaf spring from being bent in the extending direction due to the rotational moment caused by the contact of the tilting arm with the stopper portion.

(Example) An example of the present invention will be described below with reference to FIGS. 1 to 8.

This embodiment exemplifies the use of a print head, and in FIGS. 5 and 6, the piezoelectric element 1, which expands and contracts when a voltage is applied, is composed of a 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. A base 3 is provided at one end of the main frame 2 to protrude in the lateral direction for supporting 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 element 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 upper end of the rising portion of the main frame 2 . A pair of leaf springs 6.7 is fixed at one end to opposing surfaces of the movable element 5 and the main frame 2 by brazing. The plate width of both the plate springs 6 and 7 is the same as that of the main frame 2 and the movable element 5.
The width of each leaf spring 6°7 is increased by a predetermined amount from the plate thickness of the main frame 2 and the movable element 5. Each leaf spring 6 for the frame 2 and mover 5
, 7 has increased adhesion strength. Further, the leaf springs 6 and 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 element 5 in the direction of expansion and contraction of the piezoelectric element 1. A tilting body 8 is formed at the other end (extending end) of both leaf springs 6.7 and is integrally connected to the drawing leaf spring 6.7. Further, on the opposite side of the facing surfaces of both leaf springs 6.7, as shown in FIGS. 1 and 5, the main frame 2 and the movable element 5 are provided.
In the range from the upper end surface to the lower end of the tilting body 8,
Recesses 6a and 7a are formed, respectively, and the thinned portions are elastically deformable portions 6b and 7b, respectively.

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

The tilting body 8 has an arm mounting groove 8a recessed in parallel to 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 attaching it. The tilting arm 10 extends in a direction substantially perpendicular to the direction of expansion and contraction of the piezoelectric element 1, and has a notch-shaped wire attachment groove 10a formed at its tip end, and this wire attachment groove 108 has the following features:
The base end of the printing wire 711 is inserted and fixed by brazing. In addition, as shown in FIG. 5, the Moeki tilting body 8 has the portions on both sides of the leaf springs 6 and 7 in the width direction cut out to reduce the weight. Further, the tilting arm 10 is provided with through holes 9 of various sizes as appropriate 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. This parallel link mechanism 16 is shown in FIGS. 1 and 8.
As shown in the figure, a pair of link plates 17 are formed by pressing and bending two pieces of elastically deformable leaf spring material, and both link plates 17 are integrated into one body. The main body is the connecting portion 26.

The pair of link plates 17 includes a vertical link portion 18.19 parallel to the direction of expansion and contraction of the piezoelectric element 1, and a hinge portion 22.23 that can be elastically deformed between these two set link portions 18.19.
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. Furthermore, each vertical link part 19 fixed to both sides of the movable element 5
A coupling portion 26 is integrally formed across the tip of the movable member 5, and this coupling portion 26 is arranged on the upper end surface of the movable element 5 with a predetermined gap therebetween.

Further, in this embodiment, each one of the vertical link portions 1
A connecting plate 30 is integrally formed at a portion 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 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.

Further, in this embodiment, in the portion where the link plate 17 and the connecting plate 30 are arranged, the main frame 2 is thickened by an amount corresponding to the thickness of the plate. 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 subframe 4.

After the link plate 17 and the connection plate 30 are assembled between the subframe 4 and the movable element 5, the piezoelectric element 1 is installed between the base 3 of the main frame 2 and the movable element 5.
The temperature compensator 12 is assembled with the preload member 13 preloading the temperature compensator 12 by a predetermined pressure. The preload member 13 is formed in an inverted U shape, including an upper plate 13a and both side plates 13b.
The upper IJ is freely fitted over the upper surface of the base 3. −
On the other hand, a temperature compensating material 12 is fixed in advance to one end (lower end) surface of the piezoelectric element 1 in the expansion/contraction direction with an adhesive.

Then, the lower surface of the temperature compensator 12 is brought into contact with the upper surface of the upper plate 13a of the preload member 13, and the other end surface of the piezoelectric element 1 is pressed against the lower surface of the movable element 5 with a predetermined load while pushing up the preload member 13. Under these conditions, the piezoelectric element 1 is assembled by fixing both side plates 13b of the preload member 13 to both side surfaces of the base 3 by spot welding.

Further, 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.

Note that mutual contact surfaces such as the lower surface of the mover 5 and the other end surface in the expansion/contraction direction of the piezoelectric element 1, as well as the mutual contact surfaces between the lower surface of the temperature compensating material 12 and the upper surface of the upper plate 13a of the preload member 13, are coated with adhesive as necessary. glued by.

Furthermore, in this embodiment, cutout-like recesses 5a are formed at both edges in the width direction of the lower portion of the movable element 5, and the narrowed portions thereby serve as elastic stretchable portions 5b. Further, the elastic stretchable portion 5b of the movable element 5 is formed by a plate spring 7.
It has higher rigidity than the elastically deformable portion 7b of the piezoelectric element 1 and is formed to be able to elastically expand and contract slightly in the direction of expansion and contraction of the piezoelectric element 1.The predetermined displacement position of the mover 5 based on the expansion and contraction of the piezoelectric element 1 is ensured. At the same time, when the piezoelectric element 1 contracts when the voltage is cut off from being applied to the piezoelectric element 1, the elastic stretchable portion 5b of the movable element 5 slightly stretches, thereby reducing the tensile force acting on the piezoelectric element 1. Even when the piezoelectric element 1 is made of a piezoelectric ceramic having a property of being fragile under tensile force, the 11 of the piezoelectric element 1
It is designed to protect against scratches.

A first stopper member 35 made of a material having cushioning properties, such as P, B, T, (polybutylene terephthalate) resin, is disposed at the extending end of the subframe 4. As shown in FIGS. 1 and 3, the first stopper member 35 is fixed with an adhesive or the like from the end face of the extending end of the subframe 4 to a part of the side edge, and is also fixed to the tilting arm 10. It protrudes from the center of the back to the tip. A stopper portion (stopper surface) 36 is formed on the first stopper member 35, and the stopper portion (stopper surface) 36 contacts the rear surface of the tip of the tilting arm 10 so as to be able to come into contact with and separate from the tip of the tilting arm 10, thereby regulating the deflection of the tip of the tilting arm 10. ing.

Further, a second stopper member 37, which is made of the same material as the first stopper member 35 and has a shock-absorbing property, is attached to the connecting portion 26F that connects the pair of link plates 17, as shown in FIG.
They are arranged as shown in FIGS. 2 and 4. At the base of the second stopper member 37, a pair of support legs 40 that face each other across the fitting groove 39 protrude toward the end surface of the movable element 5. The second stopper member 37 is fitted into the coupling portion 26 at its fitting 11!39, and is fixed to the upper surface of the coupling portion 26 with an adhesive or the like, and the tip surface (lower end surface) of the support leg 40 ) is mover 5
It is supported in a state where it is adhered to or in contact with the end face of. Further, the second stopper member 37 is connected to the plate spring 7 of the movable element 5.
It extends along one side of the tilting body 8, and at the extending portion 37a, the side facing the tilting body 8 serves as a stopper portion 38. As the stopper portion 38 comes into contact with the tilting body 8 so as to be able to come into contact with and separate from it, the leaf spring 7 on the movable element 5 side is bent in the direction in which the tilting arm 10 extends (in the direction of arrow Q in FIG. 1). It is designed to prevent Further, an FN 41 into which the tilting arm 10 is tiltably inserted is recessed in the extending portion 37a of the second stopper member 37.

In this embodiment configured as described above, when a voltage is applied between both electrodes of the piezoelectric element 1, the piezoelectric element 1
The movable member 5 extends in the stacking direction, that is, in the direction of arrow X in FIGS. 1 and 6, by a predetermined length.
is displaced. 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. 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 at the base end of the tilting arm 10 in the direction of arrow P, and as a result, the tilting body 8 and the tilting arm 10 is tilted.

When the movable element 5 is displaced based on the elongation of the piezoelectric element 1, the movable element 5 is moved parallel to the expansion and contraction direction of the piezoelectric element 1 by each link plate 17 constituting the four-bar parallel link mechanism 16. You will be guided.

For this reason, the drawing plate spring 6.7 caused by the inclination of the movable element 5
Since the insufficient amount of deflection is prevented, the tilting body 8 and the tilting arm 10 can be tilted to a predetermined tilt angle position. Then, the printing wire 1 at the tip of the tilting arm 10
1 is guided by a predetermined number of guide members 15, and its leading end is advanced to the printing position. In this way, the leaf spring 7 on the movable element 5 side is bent more and more fully than the leaf spring 6 on the main frame 2 side, thereby making it possible to reliably tilt the tilting arm 10 to a predetermined angular position.
The elongation of the piezoelectric element 1 is significantly expanded and transmitted to the printing wire 11, thereby making it possible to prevent printing defects.

When the application of voltage to the piezoelectric element 1 is cut off, the piezoelectric element 1 contracts to its original state. Then, both the leaf springs 6 and 7
is displaced toward the direction in which the tilting arm 10 extends, which is opposite to the direction described above, by the elastic force based on the deflection. As a result, a rotation moment is generated at the base end of the tilting arm 10 in the direction of arrow Q in FIG. 1, which is the opposite direction to that described above, and the tilting arm 10 is tilted toward its original position.

After both the leaf springs 6, 7 are displaced in the direction in which the tilting arm 10 extends and reach their original positions, the leaf springs 6, 7 are
7, when the leaf spring 7 on the movable element 5 side in particular tries to bend in the extending direction, the tilting body 8 comes into contact with the stopper part 38 of the second stopper member 37, and as a result, the movable element 5 of the 5 examples Deflection of the leaf spring 7 is restricted. Therefore, vibrations of both leaf springs 6 and 7 in the directions of arrows Q and P are reduced as much as possible. As a result, elastic fatigue due to vibration of both leaf springs 6.7 can be actively reduced, and durability can be improved by preventing buckling and breakage of both leaf springs 6.7.

Further, when the tilting arm 10 is tilted to the original position based on the elastic force of the leaf springs 6 and 7, the back surface of the tilting arm 10 near the tip comes into contact with the stopper portion 36 of the first stopper member 35. Thus, further tilting of the tilting arm 10 is prevented, and the tip of the tilting arm 10 is prevented from bending.

As mentioned above, vibrations of both leaf springs 6 and 7 and tilting arm 1
By preventing the 0 tip from bending as much as possible, printing speed can be increased.

In the above-mentioned embodiment, both the first and second stopper members 35.37 are formed separately, but the invention is not limited to this, and both the first and second stopper members 35.37 are formed integrally. It may be formed into

(Effects of the Invention) As described above, according to the present invention, the movable element is displaced based on the elongation of the piezoelectric element, and both leaf springs are bent to tilt the tilting arm. On the other hand, when the voltage application is cut off and the piezoelectric element contracts to its original state, both the leaf springs are displaced in the opposite direction by the elastic force based on the deflection.

After both leaf springs reach their original positions, when the leaf spring on the movable element side tries to bend in the direction in which the tilting arm extends, the second leaf spring deflects. By regulating the vibration with the stopper part of the stopper member, the vibration of both leaf springs can be reduced as much as possible. As a result, elastic fatigue of the leaf spring caused by vibration of the leaf spring can be reduced, buckling or breakage of the leaf spring can be prevented, and durability can be improved.

Furthermore, when the tilting arm is tilted to its original position by both leaf springs, the end of the tilting arm? Since the rear side closer to 5 comes into contact with the stopper portion of the first stopper member, further tilting of the tilting arm can be prevented. Further, as described above, the second stopper can prevent the temporary spring from being bent in the extending direction due to the rotation caused by the contact of the tilting arm with the stopper portion.

As described above, by preventing the vibrations of both leaf springs and the tilting arm as much as possible, the reciprocating tilting motion of the tilting arm based on the repeated expansion and contraction of the piezoelectric element can be increased in speed. There is an effect.

[Brief explanation of the drawing]

1 to 8 of the drawings show one embodiment of the present invention, in which FIG. 1 is an enlarged side view showing the main parts of a piezoelectric element motion conversion device, and FIG. 2 is a view similar to that shown in FIG. 1. ■-■ line sectional view of , 3rd
The figure is a perspective view showing the first stopper member, FIG. 4 is a perspective view showing the second stopper member, FIG. 5 is a perspective view showing the entire piezoelectric element motion conversion device, and FIG. 6 is a side view. 7th
The figures are a sectional view taken along the line ■--■ in FIG. 6, FIG. 8 is a perspective view showing a four-section parallel link mechanism, and FIG. 9 is a side view showing the prior art. 1...Piezoelectric element 2...Main frame 5...Possible spindle 6.7...Plate spring 10...Tilt arm 35...First stopper member 36...Stopper member 37 ...Second stopper member 38...Stopper part applicant Brother Industries, Ltd.

Claims (1)

[Scope of Claims] A piezoelectric element that expands and contracts when a voltage is applied; a main 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; and the piezoelectric element. a movable element disposed at the other end in the expansion/contraction direction of the piezoelectric element; a pair of leaf springs each having one end fixed to an extension of the main frame and the movable element and extending in the expansion/contraction direction of the piezoelectric element; a tilting arm whose base end is coupled to the other end of the leaf spring, extends in a direction substantially perpendicular to the expansion and contraction direction of the piezoelectric element, and is tilted by the deflection of both the leaf springs based on the expansion and contraction of the piezoelectric element; , a first stopper member that has a stopper portion that removably abuts on the rear side of the tip of the tilting arm to restrict deflection of the tilting arm; and a leaf spring on the movable side of the two leaf springs. a second stopper member having a stopper portion that restricts bending of the tilting arm in the direction in which the tilting arm extends;