JP2682086B2 - Piezoelectric motion converter - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motion conversion device for a piezoelectric element mainly used in a print head, and more particularly to a frame having a base portion that supports one end of the piezoelectric element in the expansion / contraction direction. A motion converting device for a piezoelectric element, in which a tilting arm coupled between a movable element arranged at the other end of the piezoelectric element in the expansion / contraction direction is tilted based on displacement of the movable element due to expansion / contraction of the piezoelectric element. It is about.

(Prior Art) As a motion conversion device for a piezoelectric element of this type, for example,
Japanese Patent Application No. Sho 62-26 already developed by the same applicant
No. 8496, Japanese Patent Application No. 62-277169, and the like.

Further, in such a motion converting device for a piezoelectric element, as shown in FIG. 11, the movable element 5 is displaced based on the expansion and contraction of the piezoelectric element 1, so that the base end portions of the frame 2 and the movable element 5 are mutually displaced. By bending the pair of plate springs 6 and 7 that are fixed to each other, the tilting arm 10 coupled to the tips of the plate springs 6 and 7 is tilted.

In the motion conversion 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, the tilting arm 10 tilts backward.
At this time, the tilting arm 10 tries to retreat further from the original rest position due to inertia, so that the time required for the tilting arm 10 to stand still in the original position becomes long, and the high-speed tilting motion of the tilting arm, for example, printing It becomes difficult to deal with it at high speed. In order to quickly stop the tilting arm 10 in its original position, the tilting arm is attached to the end of the connecting member 41 fixed to the frame 2.
A stopper member 31 'for limiting the backward tilting of 10 is provided.

(Problems to be Solved by the Invention) By the way, in the above-mentioned one, the tilting arm is formed of a flat plate material oriented substantially at right angles to the stopper surface 32 'of the stopper member 31', and when the tilting arm 10 is tilted backward and backward. The tilting arm 10 comes into contact with the stopper surface 32 'of the stopper member 31' in a substantially linear contact with the plate thickness. Therefore, when the stopper member 31 is made of rubber or synthetic resin, the portion of the stopper surface 32 'of the stopper member 31' that contacts the tilting arm 10 is worn in a straight groove as shown in FIG. 32a ′, the function as a stopper is reduced early.

Further, when the stopper member 31 'is formed of a member having a hardness higher than that of the tilting arm 10, the tilting arm 10 becomes a stopper member.
There is a problem in that the portion that contacts the 31 'is worn.

In view of the above-mentioned problems, an object of the present invention is to provide a motion converting device for a piezoelectric element that can prevent mutual wear between a tilting arm and a stopper portion thereof and improve durability. .

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a frame having a base portion supporting one end of a piezoelectric element in the expansion / contraction direction, and a movable member arranged at the other end of the piezoelectric element in the expansion / contraction direction. A motion conversion device comprising a child and a tilting arm coupled between the frame and the mover and performing a tilting motion based on displacement of the mover due to expansion and contraction of the piezoelectric element, the motion converting device comprising: A stopper portion having a wear-resistant stopper surface for limiting the backward tilting of the tilting arm is provided at the position, and the tilting arm is movable toward and away from the stopper surface and the tilting arm is tilted backward and backward. In some cases, a contact portion having a wear-resistant contact surface that comes into surface contact with the stopper surface is provided.

(Operation) In the motion converting device for a piezoelectric element configured as described above, when the mover is displaced by expansion and contraction of the piezoelectric element, the tilting arm is tilted in the front-back direction based on the displacement of the mover.

When the tilting arm is tilted in the backward direction by a predetermined stroke, the contact surface of the contacting portion provided on the tilting arm comes into surface contact with the stopper surface of the stopper portion on the frame side, and further backward movement of the tilting arm is stopped. .

In this way, by limiting the backward tilting of the tilting arm by the surface contact between the contacting surface of the contacting portion provided on the tilting arm and the stopper surface of the stopper portion provided on the frame side, Mutual wear with the stopper surface is reduced. Further, since both the contact surface and the stopper surface have wear resistance, the wear between the contact surface and the stopper surface is reduced as much as possible.

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

In this embodiment, a print head is used as an example. In FIGS. 1 and 2, the piezoelectric element 1 which expands and contracts when a voltage is applied is composed of laminated piezoelectric ceramics.

Main frame 2 for supporting the piezoelectric element 1
Is a vertically elongated quadrangle extending substantially parallel to the expansion and contraction direction of the piezoelectric element 1 and is made of a metal plate having a predetermined plate thickness. A base 3 for supporting one end (lower end) of the piezoelectric element 1 in the expansion and contraction direction through a temperature compensating material 12 described later is laterally projected at one end of the main frame 2.

A mover 5 is arranged at the other end (upper end) of the piezoelectric element 1 in the expansion / contraction direction so as to face the upper end of the rising portion of the main frame 2. A pair of leaf springs 6 and 7 are fixed to the facing surfaces of the mover 5 and the main frame 2 by brazing at one end thereof. The both leaf springs 6 and 7 face each other with a predetermined gap therebetween,
Piezoelectric element 1 from the upper end surfaces of main frame 2 and mover 5
A predetermined length in the direction of expansion and contraction. A tilting body 8 is formed at the other end (extended end) of both leaf springs 6 and 7 in a state of being integrally connected to both leaf springs 6 and 7.

The tilting body 8 is provided with an arm mounting groove 8a, and a tilting arm 10 formed of a flat plate material is inserted into the arm mounting groove 8a at its base and fixed by brazing. The tilting arm 10 extends in a direction substantially orthogonal to the expansion / contraction direction of the piezoelectric element 1, and a notch-shaped wire-intermediate groove 10a is formed at the tip thereof.
The base end portion of the printing wire 11 is inserted into the wire mounting groove 10a and fixed by brazing.

A subframe 4 is integrally formed at one end of the base 3 of the main frame 2. The sub-frame 4 is provided on the other side of the piezoelectric element 1 (main frame 2
Along the opposite side) and to a position facing the mover 5.

Between the extension end of the sub-frame 4 and the mover 5, a four-bar parallel link function 16 for guiding the mover 5 in parallel with the extension and contraction direction of the piezoelectric element 1 is arranged. It is set up. As shown in FIGS. 2 and 5, the parallel link mechanism 16 includes a pair of link plates 17 formed by punching and bending a single elastically deformable leaf spring material. The main part is a connecting portion 26 that integrally connects both of these link plates 17.

The pair of link plates 17 includes vertical link portions 18 and 19 parallel to the expansion and contraction direction of the piezoelectric element 1 and both vertical link portions 18 and 19.
And a horizontal link portion 20, 21 erected by elastically deformable hinge portions 22, 23, 24, 25 between them to form a four-bar parallel link. Each one of the vertical link portions 18 of the two link plates 17 is fixed to both side surfaces of the sub-frame 4 by spot welding or the like, and each of the other vertical link portions 19 is fixed.
Are fixed to both side surfaces of the mover 5 by spot welding or the like.

In addition, in this embodiment, each of the vertical link portions
A connecting plate 30 is integrally formed at the lower part of the one end at one end thereof. Each of the connection plates 30 extends to the side surface of the main frame 2. Further, both ends of each connecting plate 30 are fixed to the side surfaces of the main frame 2 and the sub frame 4 by spot welding or the like. As a result, the sub-frame 4 is kept parallel to the main frame 2 and the rigidity of each frame 2, 4 is enhanced.

A temperature compensation material 12 is interposed between the base portion 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 compensating 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, for example, a zinc material or an aluminum material. The expansion and contraction of the piezoelectric element 1 due to the ambient temperature change is corrected by the vertical expansion of the temperature compensating material 12 so that the upper surface height of the piezoelectric element 1 is always kept constant.

The lower surface of the movable element 5 and the other end surface of the piezoelectric element 1 in the expansion / contraction direction, the lower surface of the temperature compensating member 12, and the preload member.
The mutual contact surface with the upper surface of the upper plate 13a of 12 is bonded by an adhesive as needed.

The tilting arm is provided on the extending end surface of the sub-frame 4.
A stopper member 31 is fixed by an adhesive or the like at a position facing the substantially central portion of the back surface of 10. The stopper member 31 is formed of a member having excellent wear resistance, such as zirconia ceramics, and has a stopper surface 32.
Is formed on a flat surface that is substantially parallel to the back surface of the tilting arm 10 and is several times (3 to 6 times) thicker than the plate thickness of the tilting arm 10.

On the rear surface of the tilting arm 10, at a position facing the stopper surface 32 of the stopper member 31 so as to come in contact with and away from the tilting arm 10, a width that is several times (three to six times) wider than the plate thickness of the tilting arm 10 is provided. The contact member 33 is fixed. The abutting member 33 is made of a material having the same wear resistance as the stopper member 31, and the tilting arm 10 is fitted and inserted in the widthwise central portion of the upper surface thereof as shown in FIG. The coupling groove 33a is provided as a recess. Then, the contact member 33 has the coupling groove 33a.
The tilting arm 10 is integrally fixed to the tilting arm 10 with an adhesive in a state in which the tilting arm 10 is fitted and inserted. Further, the lower surface of the contact member 33 is formed with a flat contact surface 34 that comes into surface contact with the stopper surface 32 of the stopper member 31 when the tilting arm 10 is tilted backward.

Further, in a state where the tilting arm 10 stands still at a predetermined position with no voltage applied to the piezoelectric element 1,
A slight gap (for example, about 10 μ) is set between the stopper surface 32 of the stopper member 31 and the contact surface 34 of the contact member 33. By providing this gap, the piezoelectric element 1
It is guaranteed that a compressive load is applied as described above.

In this embodiment configured as described above, when a voltage is applied between both electrodes of the piezoelectric element 1, the piezoelectric element 1
Extends in the stacking direction, that is, in the direction of arrow X in FIG. 2, for a predetermined length, and the mover 5 is displaced based on this. Then, the leaf spring 7 on the side of the mover 5 is pushed up along the leaf spring 6 on the side of the main frame 2 by receiving the displacement force of the mover 5, and both the leaf springs 6 and 7 bend in a curved shape. When the leaf spring 7 on the mover 5 side largely bends toward the leaf spring 6 on the main frame 2 side, a rotational moment is generated at the base end portion of the tilting arm 10 in the direction of arrow P, which causes the tilting arm 10. 10 is tilted forward. Then, with the printing wire 11 at the tip of the tilting arm 10 being guided by the predetermined number of guide members 15, the tip thereof is advanced to the printing position.

When the application of the voltage to the piezoelectric element 1 is cut off, the piezoelectric element 1 contracts to its original state, and the mover 5 is displaced in the opposite direction by the elastic force based on the bending of the leaf springs 6 and 7. Is done. As a result, a rotational moment in the opposite direction to the above is generated at the base end portion of the tilting arm 10, and the tilting arm 10 is tilted backward to the original position.

When the tilting arm 10 tilts backward, the tilting arm 10
Due to its inertia and the elastic force of the leaf springs 6 and 7, it tries to tilt backward further than the original position. Then, the contact surface 34 of the contact member 33 of the tilting arm 10 comes into surface contact with the stopper surface 32 of the stopper member 31, and the tilting arm 10 is further moved.
The backward tilt of is stopped. In this way, the tilting arm
By limiting the backward tilting of the tilting arm 10, the time required for the tilting arm 10 to stand still at the original position can be shortened, and the printing speed can be increased. The waveform shown by the solid line in FIG. 6 is the operation waveform at the tip of the printing wire of the apparatus of the above embodiment. Also, the waveform shown by the broken line in the figure shows the operation waveform of the preceding device (the stopper member of FIG. 10 made of synthetic resin). As is clear from each operation waveform, according to the device of this embodiment, both the vibration time and the amplitude are small.

Furthermore, the stopper surface 32 of the stopper member 31 and the contact member
Since the contact surface 34 of 33 is formed into a flat surface and makes surface contact, mutual wear between the stopper surface 32 and the contact surface 34 is reduced. Moreover, since both the stopper member 31 and the contact member 32 are formed of a member having excellent wear resistance such as zirconia ceramics, the wear of the stopper surface 32 and the contact surface 34 is further reduced.

Although the stopper member 31 and the abutting member 33 are made of a material having excellent wear resistance such as zirconia ceramics in the above-described embodiment, the invention is not limited to this.
For example, as shown in FIGS. 7 and 8, a wear-resistant metal plate, for example, a spring steel plate is bent to form a triangular contact portion having a flat contact surface 34 on its lower surface and its contact portion. The abutting member 33 is configured by a pair of leg pieces 33b that are opposed to each other with a gap into which the tilting arm 10 can be inserted from both upper end surfaces of the contact portion and that are fixed to both side surfaces of the tilting arm 10 by welding, brazing, or the like. You may.

Further, as shown in FIGS. 9 and 10, the stopper member 31
Guide walls 31a may be provided on both sides of the stopper surface 32 so as to move and guide the contact member 33 only in the tilting direction of the tilting arm 10. In this case, both guide walls 31a can prevent the lateral swing of the tilting arm 10, and the bending of the tilting arm 10 and the breakage of the printing wire 11 caused by the lateral shake of the tilting arm 10 are positively performed. Can be prevented.

Further, in the above embodiment, the tilting arm 10 and the contact member 33 and the sub-frame 4 and the stopper member 31 are formed separately, but the tilting arm 10 and the contact portion are formed integrally. A stopper portion may be formed integrally with the frame 4, and a wear-resistant sheet layer such as a ceramic layer may be provided on the contact surface of the contact portion and the stopper surface of the stopper portion.

(Effects of the Invention) As described above, according to the present invention, the tilt arm is retracted by the surface contact between the contact surface of the contact portion provided on the tilt arm and the stopper surface of the stopper portion provided on the frame side. Since the tilting can be limited, mutual wear between the contact surface and the stopper surface can be reduced, and since both the contact surface and the stopper surface have wear resistance, the contact surface And wear on the stopper surface can be reduced as much as possible,
There is an effect that the durability can be improved.

[Brief description of the drawings]

1 to 10 of the drawings show an embodiment of the present invention. FIG. 1 is a perspective view showing a motion converting device for a piezoelectric element which acts on a print head, and FIG. 2 is a side view of the same. 3 is a sectional view taken along the line III-III in FIG. 2, FIG. 4 is a sectional view taken along the line IV-IV in FIG. 2, and FIG. 5 is a perspective view showing a parallel link mechanism of four joints.
FIG. 6 is an explanatory view showing the operation waveform of the tip of the printing wire, and FIG.
FIG. 8 is a side view showing a modification of the contact member, and FIG.
VIII-VIII sectional view, FIG. 9 is a side view showing a modified example of the stopper member, and FIG. 10 is a sectional view taken along line XX of FIG. FIG. 11 is a side view showing the prior art, and FIG. 12 is a sectional view taken along the line XII-XII in FIG. 1 ...... Piezoelectric element 2 ...... Main frame 3 ...... Base part 4 ...... Sub frame 5 ...... Mover 6,7 ...... Leaf spring 10 ...... Tilt arm 31 ...... Stopper member 32 ...... Stopper surface 33 ...... Contact Contact member 34 ... Contact surface

Continuation of the front page (56) Reference JP 59-81181 (JP, A) JP 59-111859 (JP, A) JP 50-161314 (JP, A) JP 62-11654 (JP , A) JP 63-137852 (JP, A) Actually opened 54-4011 (JP, U) Actually opened 63-191030 (JP, U) Actually opened 56-8454 (JP, U)

Claims (1)

(57) [Claims] 1. A frame having a base portion for supporting one end of the piezoelectric element in the expansion / contraction direction, a mover arranged at the other end of the piezoelectric element in the expansion / contraction direction, and a frame coupled between the frame and the mover, A tilting arm that performs tilting movement based on displacement of a mover caused by expansion and contraction of a piezoelectric element, and a motion conversion device including: a predetermined position on the frame side for limiting backward tilting of the tilting arm. A stopper portion having a wear-resistant stopper surface is provided, and the tilting arm is provided with a wear-resistant contact that can come into contact with and separate from the stopper surface and that comes into surface contact with the stopper surface when the tilting arm moves backward and tilts. A motion converting device for a piezoelectric element, comprising a contact portion having a contact surface.