JP3607714B2 - Manufacturing method of ultrasonic vibrator - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a method of manufacturing the ultrasonic transducer, and more particularly, to a method of manufacturing the ultrasonic vibrator causes generating vibrations by applying an AC signal to the multilayer electric over mechanical energy conversion element.
[0002]
[Prior art]
In recent years, ultrasonic motors have attracted attention as new motors that replace electromagnetic motors. This ultrasonic motor has the following advantages over conventional electromagnetic motors.
(1) Low speed and high thrust can be obtained without using gears.
(2) Large holding force.
(3) Long stroke and high resolution.
(4) Rich in silence.
(5) Magnetic noise is not generated and is not affected by the noise.
[0003]
Such ultrasonic motors having various advantages can be roughly classified into a rotary type and a linear type depending on the driving method. With regard to the linear ultrasonic motor among these, the present applicant has previously focused on the piezoelectric longitudinal effect of the piezoelectric element and proposed an ultrasonic linear motor that has high electro-mechanical conversion efficiency and can be driven at a low voltage. Yes. In this linear motor, a driven member that is in pressure contact with the ultrasonic transducer is driven by an ultrasonic transducer that excites elliptical vibration.
[0004]
FIG. 16 shows a perspective view of an ultrasonic transducer used in this linear motor. The ultrasonic vibrator 51 has a plurality of laminated piezoelectric elements 4 as the vibration generation source, and the ultrasonic vibrator 51 having two laminated piezoelectric elements 4 is shown in the figure. The holding elastic body 53 is sandwiched between the two laminated piezoelectric elements 4, and both sides thereof are sandwiched between the holding elastic bodies 53. Note that both end portions of each of the multilayer piezoelectric elements 4 are bonded and held against the holding elastic body 53. And the ultrasonic transducer | vibrator 51 is comprised by mounting these on the basic elastic body 52 and joining each member.
[0005]
In the configuration described above, by applying an AC signal to the multilayer piezoelectric element 4, longitudinal vibration and bending vibration are generated in the multilayer piezoelectric element 4, and these vibrations are amplified and synthesized by an elastic body. Then, ultrasonic elliptical vibration is generated on the end face of the elastic body. A sliding member 55 is joined to the end face of the elastic body that is excited to maximize the amplitude of such elliptical vibration, and a driven member (not shown) is pressed through the sliding member 55. In this way, a linear motor in which the driven member moves relative to the ultrasonic transducer 51 is configured.
[0006]
In such an ultrasonic vibrator 51, in order to prevent an excessive tensile force from being applied to the multilayer piezoelectric element 4 during driving and the piezoelectric element 4 from being destroyed, a compressive stress is always applied during driving. It is necessary to keep the laminated piezoelectric element 4 in a state.
[0007]
In the previous application, the present applicant has proposed a method of joining the holding elastic body 53 to the basic elastic body 52 with a screw 54 and an adhesive. However, in the structure of the ultrasonic vibrator 51 manufactured by this bonding method, it is difficult to apply a sufficient compressive stress to the multilayer piezoelectric element 4. For this reason, when the ultrasonic vibrator 51 is driven, an alternating voltage corresponding to the resonance frequency of the longitudinal vibration is applied, and at the same time, a DC bias voltage for extending the laminated piezoelectric element 4 is applied, and apparently the laminated piezoelectric element. It was necessary to apply a sufficient compressive stress to 4.
[0008]
[Problems to be solved by the invention]
As described above, since the conventional ultrasonic linear motor needs to always apply a DC voltage, there is a possibility that the laminated piezoelectric element breaks down at high humidity, and there is a problem in durability and reliability. In addition, the drive circuit becomes complicated, and there are also problems such as circuit space and cost, especially when mounting on a camera or the like is considered.
[0009]
The present invention has been made in view of such problems, and an object thereof is to provide a method for manufacturing an ultrasonic transducer having high durability and reliability.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, a first method of manufacturing an ultrasonic transducer according to the present invention includes two elastic bodies, arranged on a first surface of the two elastic bodies, and an AC signal applied thereto. two multilayer electric over mechanical energy conversion element to vibrate the elastic body, while being disposed between the two multilayer electric over mechanical energy conversion element is sandwiched the multilayer electric over mechanical energy conversion element and an auxiliary elastic member, the state in which the two elastic bodies by clamping the electric over mechanical energy conversion element and the auxiliary elastic body of the laminated type, and the electric over mechanical energy conversion element of the stacked and compressed minute length characterized by one body of Ri by the bonding or welding the two elastic bodies Te.
The second ultrasonic transducer manufacturing method according to the present invention includes an elastic body having a convex portion at the center of the upper end and a side portion of the convex portion of the elastic body, and an AC signal is applied. Two laminated electro-mechanical energy conversion elements that vibrate the elastic body, and an auxiliary elastic body that sandwiches the laminated electro-mechanical energy conversion element together with the convex portion of the elastic body , the laminated type The electro-mechanical energy conversion element and the auxiliary elastic body are pressed against the convex portion of the elastic body with a pressing member, and the laminated electro-mechanical energy conversion element is compressed in a minute length , The laminated electro-mechanical energy conversion element, the auxiliary elastic body, and the elastic body are bonded and fixed .
Furthermore, the third method of manufacturing an ultrasonic transducer according to the present invention is the method of manufacturing the second ultrasonic transducer , wherein the auxiliary elastic body has an inclined surface at a corner, and the pressing member is the auxiliary device. has a slope corresponding to the inclined surface of the elastic body, characterized in that pressing the inclined surface of the pressing member against the inclined surface of the auxiliary elastic body.
[0011]
【Example】
Embodiments of the present invention will be described below with reference to the drawings.
1 to 6 show a first embodiment of the present invention.
As shown in FIG. 1, the elastic body of the ultrasonic transducer 1 includes a rectangular parallelepiped base 5 and two resonators 6 sandwiching the base 5 from both sides. This resonator 6 has a convex portion 6b protruding from a rectangular parallelepiped resonator body 6a on the side that becomes the side of the ultrasonic transducer 1, and by these, on the upper portion on the side facing the base 5. A notch 6c is configured. The shape of the notch 6c is substantially equivalent to the size when the laminated piezoelectric element 4 described later is pressed and assembled, and its length is longer than the length lp of the laminated piezoelectric element 4. It is shorter by a minute length Δl.
[0012]
The above members are combined as shown in FIG. That is, the laminated piezoelectric element 4 that is an electro-mechanical energy conversion element is placed in the notch 6c of the resonator 6 and is sandwiched from both sides with respect to the base 5 to apply a crimping force. Call. At this time, the multilayer piezoelectric element 4 is compressed by Δl due to the difference Δl between the length of the multilayer piezoelectric element 4 and the length of the notch 6 c of the resonator 6. In a state where the pressure is applied, the spot 6 is formed by spot welding the resonator 6 and the base 5 with a laser beam as shown in FIG. Then, as shown in the cross-sectional view of FIG. 4, the laser-welded spot welded portion 7 is deeply melted, and the base 5 and the two resonators 6 are integrated into a single continuous member.
[0013]
At this time, the convex portion 6 b of the resonator 6 and the upper portion 5 b of the base 5 constitute a holding elastic body that is an auxiliary elastic body for compressing and holding the piezoelectric element 4. The remaining lower portion 5a of the base 5 and the resonator body 6a constitute a basic elastic body that is an elastic body serving as a base.
And after performing spot welding as mentioned above, if the crimping | compression-bonding force is released | released, the ultrasonic transducer | vibrator 1 as shown in FIG. 5 can be obtained.
[0014]
Thus, an ultrasonic vibrator in which compressive stress is always applied to the multilayer piezoelectric body can be configured. Moreover, this compressive stress has the advantage that it can be easily controlled by adjusting the dimensions of each member.
[0015]
According to the first embodiment, since the compressive stress is always applied to the multilayer piezoelectric element both when it is stopped and when it is driven, it is only necessary to apply an AC voltage for driving, and a DC bias voltage is required. Therefore, dielectric breakdown of the piezoelectric element is unlikely to occur. And since each elastic body was joined by welding, the whole was integrated and became substantially uniform, and the resonance frequency of longitudinal vibration and bending vibration does not become inconsistent. Thus, an ultrasonic vibrator having high durability and reliability can be obtained.
[0016]
It is also possible to configure an ultrasonic transducer similar to the above by an elastic body divided into shapes different from those shown in the first embodiment. For example, as shown in FIG. 6, dividing in the vicinity of a line where the bending stress is zero is an example of such other dividing means. That is, the resonator 8 is obtained by dividing the lower portion 5a of the base 5 of the first embodiment into a vertical half at the center, and these are integrally provided with the two resonators 6, respectively. After assembling the resonator 6 having such a shape, the member 9 corresponding to the upper portion 5a of the base 5 and the laminated piezoelectric element 4 while applying pressure as described above, the members can be joined by laser spot welding or the like. good.
[0017]
According to the example shown in FIG. 6, since the shearing stress applied to the joint can be further reduced by the above-described divided shape, an ultrasonic vibrator having higher reliability can be obtained.
[0018]
7 to 10 show a second embodiment of the present invention. Since the second embodiment is substantially the same as the first embodiment, only different parts will be described.
As shown in FIG. 7, the elastic body of the ultrasonic transducer 1 includes two resonators 11a and 11b and a holding elastic member 12 which is an auxiliary elastic body. The two resonators 11a and 11b are provided with male and female fitting portions at portions where they are connected to each other. The resonator 11a has a convex portion 13a and the resonator 11b has a concave portion 13b. The resonators 11a and 11b are provided with notches 14a and 14b for fitting the multilayer piezoelectric element 4 in the same manner as in the first embodiment.
[0019]
The length lR2 of the notch 14a of the resonator 11a and the length lR1 of the notch 14b of the resonator 11b are as follows: the length lp of the multilayer piezoelectric element 4 and the length lb of the holding elastic member 12; There is a relationship shown in
[0020]
lR1 + lR2-lb + 2Δl = 2lp
Here, Δl is a minute length.
[0021]
As shown in FIG. 8, an adhesive 15 is applied to the parts of the above-described members that are joined to each other, and then, as shown in FIG. 9, pressure contact is applied from above, below, and both sides. At this time, due to the difference 2Δl between the length 2lp of the two laminated piezoelectric elements 4 and the length lR1 + lR2-lb of the portion sandwiched between the notches 14a and 14b of the resonators 11a and 11b and the holding elastic member 12, The two laminated piezoelectric elements 4 are each compressed by Δl. The adhesive 15 is cured with the pressure applied, and then the pressure applied is released to obtain the ultrasonic vibrator 1 as shown in FIG.
[0022]
The laminated piezoelectric element 4 is made of a resin-coated material having flexibility. (Such a multilayer piezoelectric element is, for example, the NLA series manufactured by Tokin Corporation as an example of a commercially available product.)
According to the second embodiment as described above, it has substantially the same effect as the first embodiment, and the adhesive can be cured at a temperature lower than a Curie point of, for example, 100 ° C. or less. There is an advantage that the element is not depolarized or depolarized by heating, and the quality is not deteriorated.
[0023]
11 to 15 show a third embodiment of the present invention. Since the third embodiment is substantially the same as the first and second embodiments, only different parts will be described.
As shown in FIG. 11, the elastic body of the ultrasonic transducer 1 has a resonator 21 having a rectangular parallelepiped convex portion 21a at the center of the upper end, a height substantially equal to the convex portion 21a, and a corner portion. The holding elastic member 22 is an auxiliary elastic body having an inclined surface 22a.
[0024]
The adhesive 15 is applied to each member as shown in FIG. 12, and then, as shown in FIG. 13, a pressing member 23 having an inclined surface 23a corresponding to the inclined surface 22a of the holding elastic member 22 is used. In addition to pressure contact, a pressing force is also applied from above and below. As a result, the holding elastic member 22 is pressed toward both the resonator 21 and the multilayer piezoelectric element 4. The multilayer piezoelectric element 4 is compressed by this pressing force. The adhesive is cured with the pressure applied, and then the pressure is released to obtain the ultrasonic vibrator 1 as shown in FIG.
The laminated piezoelectric element 4 of the third embodiment is covered with a flexible resin as in the second embodiment.
[0025]
According to the above configuration, the compressive force applied to the multilayer piezoelectric element can be freely controlled by controlling the pressure applied by the pressing member.
[0026]
According to the third embodiment as described above, it has substantially the same effect as the first and second embodiments, and the initial pressure applied to the multilayer piezoelectric element can be arbitrarily set using the same component configuration. It has the advantage that it can be changed. Thereby, it is possible to correct and absorb variations in characteristics of the multilayer piezoelectric element, and it is possible to keep the characteristics as an ultrasonic vibrator constant. That is, an ultrasonic transducer with higher homogeneity can be obtained.
[0027]
In the third embodiment, the members are joined by bonding. Needless to say, however, the members can be joined by laser welding as in the first embodiment. The vibrator manufactured in this case has a shape as shown in FIG.
[0028]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a method for manufacturing an ultrasonic transducer having high durability and reliability.
[Brief description of the drawings]
FIG. 1 is an exploded front view showing members of an ultrasonic transducer according to a first embodiment of the present invention.
FIG. 2 is a front view showing a state in which a pressing force is applied to each member of the ultrasonic transducer of the first embodiment.
FIG. 3 is a front view showing a state where each member of the ultrasonic transducer of the first embodiment is laser spot welded.
4 is a cross-sectional view showing a portion where the resonator of the first embodiment and the base are laser spot welded. FIG.
FIG. 5 is a perspective view showing the ultrasonic transducer of the first embodiment.
FIG. 6 is a perspective view showing another example of the ultrasonic transducer of the first embodiment.
FIG. 7 is an exploded front view showing members of an ultrasonic transducer according to a second embodiment of the present invention.
FIG. 8 is a front view showing a state in which an adhesive is applied to each member of the ultrasonic transducer of the second embodiment.
FIG. 9 is a front view showing a state in which each member of the ultrasonic transducer of the second embodiment is joined by applying a pressing force.
FIG. 10 is a perspective view showing the ultrasonic transducer of the second embodiment.
FIG. 11 is an exploded front view showing members and a pressing member of an ultrasonic transducer according to a third embodiment of the present invention.
FIG. 12 is a front view showing a state where an adhesive is applied to each member of the ultrasonic transducer of the third embodiment.
FIG. 13 is a front view showing a state in which each member of the ultrasonic transducer of the third embodiment is joined by applying a pressing force with a pressing member.
FIG. 14 is a perspective view showing the ultrasonic transducer of the third embodiment.
FIG. 15 is a perspective view showing an ultrasonic transducer formed by joining the members of the third embodiment by laser spot welding.
FIG. 16 is a perspective view showing a conventional ultrasonic transducer.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Ultrasonic vibrator 4 ... Laminated piezoelectric element (electro-mechanical energy conversion element)
5 ... Base 6, 11a, 11b, 21 ... Resonator 12, 22 ... Holding elastic member (auxiliary elastic body)

Claims (3)

Two elastic bodies,
Are arranged on the first face of the two elastic bodies, and electric over mechanical energy conversion element of the two stacked vibrating the elastic body by the AC signal is applied,
While it is disposed between the two multilayer electric over mechanical energy conversion element, and an auxiliary elastic body sandwiched the multilayer electric over mechanical energy conversion element,
The a, the two elastic bodies by sandwiching the laminated type electric over mechanical energy conversion element and the auxiliary elastic member, the electric over mechanical energy conversion element of the laminated type in a compressed state the minute length above two manufacturing method of the ultrasonic transducer, characterized in that one body of Ri by the bonding or welding the elastic body. An elastic body having a convex portion at the center of the upper end ;
Two laminated electromechanical energy conversion elements that are arranged on the side of the convex portion of the elastic body and vibrate the elastic body when an AC signal is applied;
An auxiliary elastic body for sandwiching the laminated electro-mechanical energy conversion element together with the convex portion of the elastic body;
The laminated electro-mechanical energy conversion element and the auxiliary elastic body are pressed against the convex portion of the elastic body by a pressing member, so that the laminated electro-mechanical energy conversion element has a very small length. A method for manufacturing an ultrasonic transducer, comprising: bonding and fixing the laminated electro-mechanical energy conversion element, the auxiliary elastic body, and the elastic body in a compressed state. The auxiliary elastic body has an inclined surface at a corner, the pressing member has an inclined surface corresponding to the inclined surface of the auxiliary elastic body, and presses the inclined surface of the pressing member against the inclined surface of the auxiliary elastic body. The method of manufacturing an ultrasonic transducer according to claim 2.

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