JP2005278390A - Ultrasonic vibrator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a bolting Langevin type ultrasonic vibrator in which vibration energy can be transmitted efficiently even when the same piezoelectric material is used by reducing a gap at a contact part of a piezoelectric ceramics and each component thereby preventing vibration efficiency of the ultrasonic vibrator from lowering. <P>SOLUTION: In the Langevin type ultrasonic vibrator comprising a bolt, a nut, a piezoelectric ceramics, and an electrode plate, contact parts of the bolt, nut and piezoelectric ceramics are bonded by an adhesive. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ultrasonic transducer that can be used as a drive element for an ultrasonic motor used in an electronic apparatus such as a positioning device.

  Conventionally, two bolt-clamped Langevin type ultrasonic transducers, a holding unit for holding the ultrasonic transducers at a predetermined angle (for example, 90 degrees), and a substantially V-shaped shape, its apex portion There is known a resonance type ultrasonic motor provided with a tip which is in contact with a rotor which is a driven body and which is connected to an ultrasonic transducer at an end thereof (the V-shaped open side) (For example, refer to Patent Document 1).

Here, FIG. 1 shows a schematic perspective view of a conventional bolt-clamped Langevin type ultrasonic transducer, and FIG. 2 shows a sectional view thereof.
The ultrasonic vibrator 1 includes a bolt 2 threaded at both ends, two nuts 3a and 3b having screw holes that fit into the thread grooves of the bolt 2, and two rings through which the bolt 2 can pass. Piezoelectric ceramics 4a and 4b, and two ring-shaped electrode plates 5a and 5b through which the bolt 2 can pass.

Next, FIG. 3 shows a schematic assembly diagram of a conventional bolted Langevin type ultrasonic transducer.
The Langevin type ultrasonic vibrator is configured by bolting a bolt passed through a hole of piezoelectric ceramic with a predetermined force with a nut.
That is, as shown in FIG. 3, the piezoelectric ceramic 4a is disposed so as to be sandwiched between the electrode plates 5a and 5b, and the piezoelectric ceramic 4b is disposed on the upper surface of the electrode plate 5b.
Next, the bolt 2 is passed through the hole portions of the electrode plate and the piezoelectric ceramic, and the nuts 3a and 3b are attached to the end portions of the bolt 2, respectively, and then tightened with a predetermined force. Thus, a Langevin type ultrasonic transducer is obtained.

JP 2000-152671 A

The conventional bolt-clamped Langevin type ultrasonic vibrator described above clamps and fixes the piezoelectric ceramic by bolting, but the contact portion between the piezoelectric ceramic and each component is not a smooth surface of the piezoelectric ceramic. It is not completely attached.
For this reason, even after tightening at the contact part between the piezoelectric ceramic and each component, a slight gap will be generated, so the Langevin type ultrasonic vibrator will resonate with air with the highest ultrasonic reflectance. As a result, there is a problem that spurious vibration is caused, resonance impedance is increased, and vibration efficiency is decreased.

  The present invention has been completed by diligently studying to solve the above-described problems. The clearance between the piezoelectric ceramic of the Langevin type ultrasonic vibrator and the contact portion of each component is reduced, and the ultrasonic vibrator The purpose is to suppress a decrease in vibration efficiency.

  That is, a Langevin type ultrasonic vibrator, the ultrasonic vibrator comprising a bolt, a nut, a piezoelectric ceramic, and an electrode plate, and the bolt, the nut, the piezoelectric ceramic, and the electrode plate are mutually connected. The ultrasonic transducer is characterized in that the contact portion is bonded with an adhesive.

  In a preferred embodiment, a Langevin type ultrasonic vibrator comprising a bolt, a nut, a piezoelectric ceramic, and an electrode plate, and an external electrode formed on the surface after polarization is provided. The removed piezoelectric ceramic, the bolt, the nut, and the electrode plate are brought into contact with each other and bolted.

In the components of the Langevin type ultrasonic transducer, the contact surfaces are all adhered to each other with an adhesive to improve the adhesion of the contact surface, increasing the efficiency of vibration transmission and suppressing spurious vibrations. There is.
Moreover, since heat generation due to energy loss due to vibration is suppressed, when used as an ultrasonic motor, thrust and speed can be increased.
Similarly, when the piezoelectric ceramic is polarized, the external electrodes formed on the surface of the piezoelectric ceramic are removed, and then each component of the piezoelectric ceramic, bolt, nut, and electrode plate is brought into contact with each other and bolted. This has the same effect as bonding all the contact portions of the piezoelectric ceramic, bolt, nut, and electrode plate with an adhesive.

  In the present invention, as a first invention, there is a Langevin type ultrasonic vibrator, wherein the ultrasonic vibrator bonds a contact portion of a bolt, a nut, a piezoelectric ceramic, and an electrode plate with an adhesive. We have proposed an ultrasonic transducer characterized by this.

  Here, the reason for adhering the contact parts of the bolt, nut, piezoelectric ceramics, and electrode plate, which are components of the ultrasonic vibrator, with an adhesive is that by contact with only conventional mechanical bolting, This is because the contact portion between the piezoelectric ceramic and each component is not completely adhered.

  That is, in the present invention, the contact portion can be closely adhered by filling the gap after the piezoelectric ceramic and each component are tightened with the adhesive.

Here, as the adhesive of the present invention, for example, an epoxy-based or silicon-based resin-based adhesive or an inorganic adhesive can be used.
The adhesive may not be conductive. The reason for this is that there is a portion where the adhesive layer hardly intervenes in the contact portion of each component due to mechanical pressure by bolting, so that electrical contact with each other is maintained.

  Next, PZT ceramics are usually used for the piezoelectric ceramics of the present invention, and electrodes (not shown) are baked on the front and back surfaces of the piezoelectric ceramics. In the polarization treatment, a DC strong electric field of 1 to 3 kV / mm is applied between the front and back electrodes to align the internal electric dipoles in a certain direction.

  Further, the bolts and nuts are made of metal, and those having a fixed shape are not used, but those having various shapes are used depending on the mode of use.

Hereinafter, the present invention will be described in detail with reference to FIG. 3 which is an assembly drawing of a Langevin type ultrasonic transducer.
(1) Example 1
An epoxy adhesive (not shown) is applied to the front and back surfaces of the piezoelectric ceramic 4a having electrodes baked on the front and back surfaces, and then disposed so as to be sandwiched between the electrode plates 5a and 5b, and the upper surface of the electrode plate 5b. After applying an epoxy adhesive (not shown) to the piezoelectric ceramic 4b.
Next, the contact portion between the nut 3a and the electrode plate 5b, and the piezoelectric ceramic 4b and the nut 3b
An epoxy adhesive (not shown) is applied to the contact portions of the nuts 3a and 3b, the screw holes of the female screws of the nuts 3a and 3b, the holes of the piezoelectric ceramics 4a and 4b, and the screw portions of the bolts 2; Bolts 2 were passed through the holes, and nuts 3a and 3b were attached to both ends of the bolts 2 (threaded with male screws), respectively, and bolted at 50 N · m. Further, excess epoxy adhesive was wiped off and removed.
After the epoxy adhesive was cured, a 3 kV / mm direct current strong electric field was applied to the electrode plate to polarize the piezoelectric ceramics 4a and 4b to obtain a Langevin type ultrasonic vibrator of the present invention.

(2) Comparative Example 1
In Example 1, each component of the ultrasonic vibrator was bonded after being assembled with an adhesive, but as Comparative Example 1, each component was not bonded. First, as shown in FIG. 3, contact parts of the piezoelectric ceramics 4a and 4b, electrode plates 5a and 5b, nuts 3a and 3b, and bolts 2 (both ends are threaded with male screws) are shown. The nuts 3a and 3b were bolted at 50 N · m. Next, a 3 kV / mm direct current strong electric field was applied to the electrode plate to polarize the piezoelectric ceramics 4a and 4b to obtain a Langevin type ultrasonic vibrator of the present invention.

(3) Evaluation The output (W) when the obtained Langevin type ultrasonic transducer was driven and the temperature rise value of the ultrasonic transducer at that time were measured with a radiation thermometer. The result is shown in FIG. From the figure, it was found that when the ultrasonic vibrator was configured without bonding after incorporating each component which is Comparative Example 1, the temperature rise was large due to the friction loss of the contact portion. On the other hand, in Example 1 of this invention, it has confirmed that the temperature rise with respect to an output was small.
Therefore, it has been found that even when the same piezoelectric material is used, according to the present invention, vibration energy is efficiently transmitted.

  Also, in the present invention, as a second invention, a Langevin type ultrasonic vibrator comprising a bolt, a nut, a piezoelectric ceramic, and an electrode plate is formed on a surface after being polarized. An ultrasonic vibrator is proposed in which the piezoelectric ceramic, the bolt, the nut, and the electrode plate from which external electrodes are removed are brought into contact with each other and bolted.

  Here, the reason for removing the external electrodes formed on the front and back surfaces of the piezoelectric ceramic after polarization of the piezoelectric ceramic is that the thickness of the external electrode is about 10 μm, and the surface roughness of the surface on which the external electrode is formed is 10 μm. As described above, in the contact only by the conventional mechanical bolting, a gap is generated in the contact portion between the piezoelectric ceramic and each component.

  In other words, in the present invention, after the piezoelectric ceramic is polarized, the external electrodes formed on the front and back surfaces of the piezoelectric ceramic are removed, and then the components of the ultrasonic vibrator are bolted together so that the contact portion can be adhered. It becomes.

  Here, as a method of removing the external electrode of the polarized piezoelectric ceramic, precise lapping and mirror finishing are suitable, but if the parallelism of the front and back surfaces of the piezoelectric ceramic is maintained, the external electrode can be cut by cutting. May be removed.

  Piezoelectric ceramics use PZT-based ceramics, electrodes (not shown) are baked on the front and back surfaces of the piezoelectric ceramics, and polarization treatment is performed by applying a DC strong electric field of 1 to 3 kV / mm between the front and back electrodes. As in the first invention of the present invention, the internal electric dipoles are aligned in a certain direction, and the bolts and nuts are made of metal.

Hereinafter, the present invention will be described in detail with reference to FIG. 3 which is an assembly drawing of a Langevin type ultrasonic transducer.
(1) Example 2
Polarization treatment was performed on a piezoelectric ceramic whose electrodes were baked on the front and back surfaces by applying a strong DC electric field of 3 kV / mm between the electrodes.
Next, the external electrodes formed on the front and back surfaces of the polarized piezoelectric ceramic were polished with a single-sided lapping machine, and lapped until the electrodes disappeared. As a result, the surface roughness of the front and back surfaces of the piezoelectric ceramic was about 2 to 3 μm.
Next, after polarization, it is placed so as to be sandwiched between the electrode plates 5a and 5b on the front and back surfaces of the piezoelectric ceramic 4a from which the external electrodes on the front and back surfaces have been removed by lapping, and further polarized and lapped on the upper surface of the electrode plate 5b. The piezoelectric ceramic 4b from which the external electrodes on the front and back surfaces were removed was disposed.
The contact portion between the nut 3a and the electrode plate 5b, and the piezoelectric ceramic 4b and the nut 3b
The bolts 2 are passed through the contact portions of the nuts 3a and 3b and the screw holes of the female screws of the nuts 3a and 3b and the holes of the piezoelectric ceramics 4a and 4b, and the nuts 3a and 3b are inserted into both ends of the bolt 2 (threaded with male screws). The nuts 3a and 3b were bolted at 50 N · m.

(2) Comparative Example 2
First, after applying a DC strong electric field of 3 kV / mm between the electrodes on the front and back surfaces of the piezoelectric ceramics 4a and 4b for polarization, the piezoelectric ceramics 4a and 4b having external electrodes formed on the front and back surfaces, and the electrode plates 5a, 5b, nuts 3a and 3b, and bolts 2 (both ends are threaded with male screws) are assembled as shown in FIG. 3, and nuts 3a and 3b are bolted at 50 N · m. Tightened.

(3) Evaluation The output (W) when the obtained Langevin type ultrasonic transducer was driven and the temperature rise value of the ultrasonic transducer at that time were measured with a radiation thermometer. The result is shown in FIG. From the figure, it was found that when the ultrasonic vibrator was configured by incorporating piezoelectric ceramics with external electrodes formed on the front and back surfaces, which are comparative examples, and other components, the temperature rise was large due to friction loss at the contact portion. . On the other hand, in Example 2 of this invention, it has confirmed that the temperature rise with respect to an output was small. As a result, it was found that the same result as in Example 1 was obtained in Example 2.
Therefore, the vibration energy efficiency is almost the same regardless of whether the components of the ultrasonic vibrator are brought into contact with an adhesive or when the piezoelectric ceramic with the external electrode removed after polarization is bolted to other components. I understood that it communicates well.

  The present invention is suitable for use of an ultrasonic motor used for driving an XY stage apparatus mounted on a semiconductor manufacturing apparatus or the like.

It is a typical perspective view of a bolted Langevin type ultrasonic transducer. It is a typical sectional view of a bolted Langevin type ultrasonic transducer. It is a typical assembly drawing of a bolted Langevin type ultrasonic transducer. It is a figure which shows the output and temperature rise value of a Langevin type ultrasonic transducer at the time of fully bonding component parts. It is a figure which shows the output and temperature rise value of a Langevin type ultrasonic transducer at the time of bolting the piezoelectric ceramic from which the external electrode is removed, and other components.

Explanation of symbols

1: Ultrasonic vibrator 2: Bolt 3a, 3b: Nut 4a, 4b: Piezoelectric ceramics 5a, 5b: Electrode plate

Claims (2)

  A Langevin type ultrasonic vibrator comprising a bolt, a nut, a piezoelectric ceramic, and an electrode plate, wherein the bolt, the nut, the piezoelectric ceramic, and the electrode plate are in contact with each other. An ultrasonic transducer characterized in that is bonded with an adhesive.   A Langevin type ultrasonic vibrator, the ultrasonic vibrator comprising a bolt, a nut, a piezoelectric ceramic, and an electrode plate, wherein the piezoelectric ceramic is obtained by removing external electrodes formed on the surface after polarization, An ultrasonic vibrator, wherein the bolt, the nut, and the electrode plate are brought into contact with each other and bolted.

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