JP2007288289A - Ultrasonic transducer and ultrasonic cleaner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic transducer or the like enabling transmission efficiency or the like of an ultrasonic wave to be increased, while preventing damage to a piezoelectric ceramics and a vibrating body due to thermal stress. <P>SOLUTION: The ultrasonic transducer 100 is provided with the piezoelectric ceramics 110 and the vibrating body 120 for delivering the ultrasonic wave generated by the piezoelectric ceramics 110. Then an intermediate plate 130 is interposed between the piezoelectric ceramics 110 and the vibrating body 120. The coefficient of thermal expansion of the intermediate plate 130 is a value between the thermal expansion coefficient of the piezoelectric ceramics 110 and the thermal expansion coefficient of the vibrating body 120, and the acoustic impedance of the intermediate plate 130 is a value between the acoustic impedance of the piezoelectric ceramics 110 and the acoustic impedance of the vibrating body 120. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ultrasonic vibrator including a piezoelectric ceramic and a vibrating body that transmits ultrasonic waves generated by the piezoelectric ceramic, and an ultrasonic cleaning machine including such an ultrasonic vibrator.

  2. Description of the Related Art Conventionally, an ultrasonic vibrator including a piezoelectric ceramic and a vibration body (for example, a vibration plate, a vibration transmission body, an ultrasonic radiation plate, etc.) that transmits ultrasonic waves generated by the piezoelectric ceramic is known. Such an ultrasonic vibrator is caused by a difference in thermal expansion coefficient between the piezoelectric ceramic and the vibrating body when the usage environment is high or when the bonding temperature between the piezoelectric ceramic and the vibrating body is high in the manufacture. As a result, thermal stress is generated on the joint surface between the piezoelectric ceramic and the vibrating body. As a result, the ultrasonic vibrator may be damaged, for example, the piezoelectric ceramic or the vibrating body may break.

  As a method for solving the damage caused by the thermal stress, it is conceivable to use an elastic adhesive for joining the piezoelectric ceramic and the vibrating body. This is because the thermal stress generated on the joint surface is absorbed by the elastic deformation of the elastic adhesive, thereby preventing the piezoelectric ceramics and the vibrating body from being damaged. As another method for solving the damage caused by thermal stress, there is a method disclosed in Patent Document 1. That is, a mesh-like stainless steel sheet is placed in an adhesive layer that joins the piezoelectric ceramic and the vibrating body. This is because the thermal stress generated on the joint surface is absorbed by the elastic deformation of the stainless steel sheet, thereby preventing the piezoelectric ceramics and the vibrating body from being damaged.

JP 2000-22474 A

  However, when an elastic adhesive is used for joining the piezoelectric ceramic and the vibrating body, the ultrasonic vibration itself is suppressed at the elastic adhesive portion, and the transmission efficiency and radiation efficiency of the ultrasonic wave are reduced. In addition, when a mesh-like stainless steel sheet is put in the adhesive layer, the adhesive layer is not a uniform layer, and in this case also, the transmission efficiency and radiation efficiency of the ultrasonic waves are lowered. Thus, conventionally, it has been difficult to improve the transmission efficiency and radiation efficiency of ultrasonic waves while preventing breakage due to the thermal stress of piezoelectric ceramics and vibrators.

  The present invention has been made in view of the present situation, and is an ultrasonic vibration capable of improving ultrasonic transmission efficiency and radiation efficiency while preventing breakage due to thermal stress of a piezoelectric ceramic or a vibrating body. It is an object of the present invention to provide a child and an ultrasonic cleaning machine including such an ultrasonic vibrator.

  The solution is an ultrasonic vibrator including a piezoelectric ceramic and a vibrating body that transmits ultrasonic waves generated by the piezoelectric ceramic, and is disposed between the piezoelectric ceramic and the vibrating body. A plurality of intermediate plates, the thermal expansion coefficient of which has a value between the thermal expansion coefficient of the piezoelectric ceramic and the thermal expansion coefficient of the vibrating body, and the acoustic impedance of the intermediate plate The ultrasonic transducer includes one or more intermediate plates having a value between an impedance and an acoustic impedance of the vibrating body.

  According to the present invention, the intermediate plate is interposed between the piezoelectric ceramic and a vibration body such as a vibration plate, a vibration transmission body, and an ultrasonic radiation plate. This intermediate plate has a thermal expansion coefficient between the thermal expansion coefficient of the piezoelectric ceramic and the thermal expansion coefficient of the vibrator. For this reason, even if this ultrasonic vibrator is exposed to high temperatures in its usage environment or manufacturing process, thermal stress generated between the piezoelectric ceramic and the intermediate plate or thermal stress generated between the intermediate plate and the vibrator However, it becomes smaller than the conventional case where the piezoelectric ceramic and the vibrating body are directly joined. Therefore, it is possible to prevent the ultrasonic vibrator from being damaged such as the piezoelectric ceramics and the vibrating body cracking due to the thermal stress.

  Further, the acoustic impedance of the intermediate plate of the present invention has a value between the acoustic impedance of the piezoelectric ceramic and the acoustic impedance of the vibrating body. For this reason, compared with the case where the piezoelectric ceramic and the vibrating body are directly joined without an intermediate plate, the difference in acoustic impedance between the piezoelectric ceramic and the intermediate plate and between the intermediate plate and the vibrating body is reduced. Ultrasonic reflection can be suppressed and ultrasonic waves can be transmitted efficiently. Therefore, in this ultrasonic transducer, it is possible to improve ultrasonic conduction efficiency and radiation efficiency as compared with the conventional case.

Here, the “piezoelectric ceramics” is not particularly limited as long as it generates ultrasonic vibration by an electric signal.
The “vibrating body” may be anything that transmits ultrasonic waves generated by piezoelectric ceramics, and the shape, material, and the like thereof can be appropriately selected according to the use of the ultrasonic vibrator. The vibrating body can be formed of a material such as metal, resin, or glass, for example.
As long as the “intermediate plate” satisfies the above requirements, its shape, form, and the like can be selected as appropriate. The intermediate plate can be formed of a material such as metal, resin, glass, or ceramics.

  Further, in the ultrasonic vibrator described above, the thickness of the piezoelectric ceramic corresponds to 1/2 of the wavelength λp of the ultrasonic wave transmitted through the piezoelectric ceramic, and the thickness of the intermediate plate corresponds to the wavelength λi of the ultrasonic wave transmitted through the intermediate plate. An ultrasonic transducer in which the sum of the ratio and the ratio of the thickness of the vibrator to the wavelength λv of the ultrasonic wave transmitted through the vibrator is ½ is preferable.

  According to the present invention, the thickness of the piezoelectric ceramic corresponds to ½ of the wavelength λp of the ultrasonic wave transmitted through the piezoelectric ceramic. Further, the sum of the ratio of the thickness of the intermediate plate to the wavelength λi of the ultrasonic wave transmitted through this and the ratio of the thickness of the vibrating body to the wavelength λv of the ultrasonic wave transmitted through this is within a range of 1/2 ± 1/10. is there. For this reason, the piezoelectric ceramic can be made to resonate at half wavelength, and the intermediate plate and the vibrator can be made to resonate at almost half wavelength. Therefore, the ultrasonic output of the ultrasonic transducer can be improved.

In addition, the case where the sum of the ratio of the thickness of the intermediate plate to the wavelength λi of the ultrasonic wave transmitted through this and the ratio of the thickness of the vibrating body to the wavelength λv of the ultrasonic wave transmitted through the intermediate plate is not exactly ½ is included. For the following reasons.
That is, since an adhesive layer is interposed between the piezoelectric ceramic and the intermediate plate, and between the intermediate plate and the vibrating body, there is an influence due to the thickness of these adhesive layers. In addition, the piezoelectric ceramic and the intermediate plate, and the intermediate plate and the vibrating body have different materials and characteristics (longitudinal elastic modulus, thermal expansion coefficient, etc.) and are constrained to each other via the adhesive layer. For this reason, it is considered that the sound velocity of the ultrasonic vibration actually transmitted through the intermediate plate and the vibrating body is a value deviated from the sound velocity when measured in a free state without restraining them. Due to these effects, in the ultrasonic vibrator having the piezoelectric ceramic, the intermediate plate, and the vibrator, the ratio of the thickness of the intermediate plate to the wavelength λi and the wavelength λv of the vibrator when the ultrasonic output is maximized. This is because there is a case where the sum of the ratio and the ratio is slightly deviated within a range of 1/2 to 1/10.

  Further, in the ultrasonic vibrator, the ratio of the thickness of the piezoelectric ceramic to the wavelength λp of the ultrasonic wave transmitted through the piezoelectric ceramic, the ratio of the thickness of the intermediate plate to the wavelength λi of the ultrasonic wave transmitted through the piezoelectric ceramic, and the vibration It is preferable to use an ultrasonic transducer in which the sum of the thickness of the body and the ratio of the ultrasonic wave transmitted through the body to the wavelength λv is 1/2.

According to the present invention, the ratio of the thickness of the piezoelectric ceramic to the wavelength λp of the ultrasonic wave transmitted through this, the ratio of the thickness of the intermediate plate to the wavelength λi of the ultrasonic wave transmitted through this, and the ultrasonic wave transmitted through the thickness of the vibrator. Is in the range of 1/2 ± 1/10. For this reason, the piezoelectric ceramic, the intermediate plate, and the vibrating body can be made to resonate almost half wavelength as a whole. Therefore, also in this case, the ultrasonic output of the ultrasonic transducer can be improved.
The ratio of the thickness of the piezoelectric ceramic to the wavelength λp of the ultrasonic wave transmitted through this, the ratio of the thickness of the intermediate plate to the wavelength λi of the ultrasonic wave transmitted through this, and the thickness of the vibrator relative to the wavelength λv of the ultrasonic wave transmitted through this. The reason why the sum with the ratio is not exactly ½ is as follows. That is, since an adhesive layer is interposed between the piezoelectric ceramic and the intermediate plate, and between the intermediate plate and the vibrating body, there is an influence due to the thickness of these adhesive layers. Further, the piezoelectric ceramic and the intermediate plate, and the intermediate plate and the vibrating body are different in material and characteristics (longitudinal elastic modulus, thermal expansion coefficient, etc.) and are constrained to each other via the adhesive layer. For this reason, it is considered that the speed of ultrasonic vibration actually transmitted through the piezoelectric ceramic, the intermediate plate, and the vibrating body is a value deviated from the speed of sound when measured in a free state without restraining them. Due to these effects, in the ultrasonic vibrator having the piezoelectric ceramic, the intermediate plate, and the vibrator, the ratio of the thickness of the piezoelectric ceramic to the wavelength λp and the wavelength λi of the thickness of the intermediate plate when the ultrasonic output is maximized. This is because the sum of the ratio with respect to and the ratio of the thickness of the vibrator to the wavelength λv may be slightly deviated within a range of 1/2 to 1/10.

  Furthermore, in the ultrasonic vibrator according to any one of the above, the vibrator is preferably made of quartz glass, and the intermediate plate is preferably an ultrasonic vibrator made of low thermal expansion ceramics.

Quartz glass has a small coefficient of thermal expansion and a large difference from the coefficient of thermal expansion of piezoelectric ceramics. Therefore, in an ultrasonic vibrator in which a vibrating body is formed from quartz glass and a piezoelectric ceramic and a vibrating body are directly joined as in the past, Damage due to thermal stress is particularly likely to occur. Therefore, when the vibrating body is made of quartz glass, if an intermediate plate is interposed between the piezoelectric ceramic and the vibrating body as in the present invention, damage due to thermal stress of the ultrasonic vibrator is more effectively prevented. it can.
Further, by using a low thermal expansion ceramic as the intermediate plate, it is possible to easily form the intermediate plate that satisfies the above-described thermal expansion coefficient and acoustic impedance.

  Another solution is an ultrasonic cleaner provided with any of the ultrasonic transducers described above.

  Such an ultrasonic cleaning machine is reliable because the ultrasonic vibrator can improve the transmission efficiency and radiation efficiency of ultrasonic waves while preventing damage due to thermal stress as described above. It can be high and high performance.

(Embodiment 1)
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows an ultrasonic transducer 100 according to the first embodiment. The ultrasonic vibrator 100 includes a piezoelectric ceramic 110, a vibrating body 120, and an intermediate plate 130. Specifically, the intermediate plate 130 is interposed between the piezoelectric ceramic 110 and the vibrating body 120 via the adhesive layers 141 and 142.

Among these, the piezoelectric ceramic 110 resonates by a high frequency input given through a lead wire (not shown), and generates an ultrasonic vibration of 3 MHz in the thickness direction. The piezoelectric ceramic 110 has a disk shape with a diameter of 20 mm and a thickness of 0.70 mm. This thickness corresponds to ½ of the wavelength λp (1.4 mm) of the ultrasonic wave transmitted through the thickness. The piezoelectric ceramic 110 has a thermal expansion coefficient of 1.80 × 10 ⁻⁶ (1 / ° C.) and an acoustic impedance of 32.3 × 10 ⁶ (N · s / m ³ ).

The vibrating body 120 has a disk shape with a diameter of 20 mm and a thickness of 0.20 mm, and is made of quartz glass. The ratio of the thickness (0.20 mm) of the vibrating body 120 to the wavelength λv (1.81 mm) of the ultrasonic wave transmitted through the vibrating body 120 is 0.11. The vibrating body 120 has a thermal expansion coefficient of 0.47 × 10 ⁻⁶ (1 / ° C.) and an acoustic impedance of 13.2 × 10 ⁶ (N · s / m ³ ).

Next, the intermediate plate 130 will be described. The intermediate plate 130 has a disk shape with a diameter of 20 mm and a thickness of 0.45 mm. The ratio of the thickness (0.45 mm) of the intermediate plate 130 to the wavelength λi (1.52 mm) of the ultrasonic wave transmitted through the intermediate plate 130 is 0.30. The intermediate plate 130 is made of a low thermal expansion ceramic. The intermediate plate 130 has a thermal expansion coefficient of 1.40 × 10 ⁻⁶ (1 / ° C.) and an acoustic impedance of 14.3 × 10 ⁶ (N · s / m ³ ).

In such an ultrasonic transducer 100, the thermal expansion coefficient (1.40 × 10 ⁻⁶ (1 / ° C.)) of the intermediate plate 130 is equal to the thermal expansion coefficient (1.80 × 10 ⁻⁶ (1) of the piezoelectric ceramic 110. / ° C.)) and the thermal expansion coefficient of the vibrating body 120 (0.47 × 10 ⁻⁶ (1 / ° C.)). For this reason, even if this ultrasonic vibrator 100 is exposed to a high temperature in its usage environment or manufacturing process, thermal stress generated between the piezoelectric ceramic 110 and the intermediate plate 130, or between the intermediate plate 130 and the vibrating body 120. The thermal stress generated in the above becomes smaller than that of the conventional ultrasonic vibrator that directly joins the piezoelectric ceramic and the vibrating body. Therefore, it is possible to prevent the ultrasonic vibrator 110 from being damaged, such as the piezoelectric ceramic 110 and the vibrating body 120 being cracked due to thermal stress.

In particular, since the vibrating body 120 is made of quartz glass, its thermal expansion coefficient is as small as 0.47 × 10 ⁻⁶ (1 / ° C.), and the thermal expansion coefficient of the piezoelectric ceramic 110 (1.80 × 10 ⁻⁶ (1 / C))) is large. For this reason, in the conventional ultrasonic vibrator in which the piezoelectric ceramic and the vibrating body are directly joined, the piezoelectric ceramic and the vibrating body are likely to break due to thermal stress. However, as described above, in the first embodiment, since the generated thermal stress is reduced by interposing the intermediate plate 130, the ultrasonic transducer 100 can be more effectively prevented from being damaged.

The acoustic impedance (14.3 × 10 ⁶ (N · s / m ³ )) of the intermediate plate 130 is equal to the acoustic impedance (32.3 × 10 ⁶ (N · s / m ³ )) of the piezoelectric ceramic 110 and vibration. It is a value between the acoustic impedance of the body 120 (13.2 × 10 ⁶ (N · s / m ³ )). Therefore, the acoustic impedance difference between the piezoelectric ceramic 110 and the intermediate plate 130 and between the intermediate plate 130 and the vibrating body 120 is smaller than when the piezoelectric ceramic 110 and the vibrating body 120 are directly joined without the intermediate plate 130. Thus, reflection of ultrasonic waves at these interfaces is suppressed, and ultrasonic waves can be transmitted efficiently. Therefore, this ultrasonic transducer 100 can improve the conduction efficiency and radiation efficiency of ultrasonic waves as compared with the conventional case.

In the first embodiment, as described above, the thickness of the piezoelectric ceramic 110 corresponds to ½ of the wavelength λp of the ultrasonic wave transmitted through the piezoelectric ceramic 110. Therefore, it can be seen that the piezoelectric ceramic 110 can be made to resonate at half wavelength.
The ratio of the thickness of the vibrating body 120 to the wavelength λv of the ultrasonic wave transmitted through this is 0.11, and the ratio of the thickness of the intermediate plate 130 to the wavelength λi of the ultrasonic wave transmitted through this is 0.30. is there. Therefore, the sum of these ratios is 0.41, which is in the range of 1/2 ± 1/10. For this reason, the vibrating body 120 and the intermediate | middle board 130 can be made to resonate substantially half wavelength.
Therefore, this ultrasonic transducer 100 can further improve the ultrasonic output.

In addition, the ratio (0.11) of the thickness of the vibrating body 120 to the wavelength λv of the ultrasonic wave transmitted through this, and the ratio (0.30) of the thickness of the intermediate plate 130 to the wavelength λi of the ultrasonic wave transmitted through the vibrator 120. The reason why the sum (0.41) was not exactly ½ (= 0.5) is considered to be due to the following reason.
First, the influence of the thicknesses (about 0.1 mm each) of the adhesive layers 141 and 142 interposed between the piezoelectric ceramic 110 and the intermediate plate 130 and between the intermediate plate 130 and the vibrating body 120 can be considered.
In addition, although the piezoelectric ceramic 110 and the intermediate plate 130 and the intermediate plate 130 and the vibrating body 120 are different in material and characteristics (longitudinal elastic modulus, thermal expansion coefficient, etc.), they are constrained via the adhesive layers 141 and 142. I'm happy. For this reason, it is considered that the sound speed of the ultrasonic vibration actually transmitted through the intermediate plate 130 and the vibrating body 120 is a value deviated from the sound speed when measured in a free state without restraining them.
Due to these effects, when the thickness of the intermediate plate 130 and the vibration plate 120 is adjusted so that the ultrasonic output is maximized in the ultrasonic vibrator 100, the ratio of the thickness of the intermediate plate 130 to the wavelength λi, and the vibration body 120. It is considered that the sum of the ratio of the thickness to the wavelength λv is slightly deviated from 1/2 (0.41 in this example).

  Here, specifically showing the effect, the ultrasonic output of the ultrasonic transducer 100 of the first embodiment was 160 mV to 180 mV. On the other hand, in the conventional ultrasonic vibrator in which a stainless mesh having a thickness of about 0.2 mm is interposed between the piezoelectric ceramic 110 and the vibrating body 120 instead of the intermediate plate 130, the ultrasonic output is 80 mV. There was only ~ 135 mV. The ultrasonic output was measured as a voltage value by an ultrasonic sound pressure meter HUS-5 manufactured by Honda Electronics.

Next, the ultrasonic cleaner 150 according to the first embodiment will be described with reference to FIG. The ultrasonic cleaner 150 is for cleaning the work W by irradiating the work W such as a silicon chip with ultrasonic waves.
The ultrasonic cleaner 150 includes the ultrasonic transducer 100 and a guide 160 that fixes the ultrasonic transducer 100. A through-hole 160c is formed in the guide 160. Then, the packing 170 is interposed between the guide 160 and the vibrating body 120 of the ultrasonic transducer 100, and the ultrasonic transducer 100 is fixed to the guide 160 so that the vibrating body 120 is exposed in the through hole 160c. ing.

  Such an ultrasonic cleaner 150 is highly reliable because the ultrasonic transducer 100 can improve the transmission efficiency of ultrasonic waves while preventing damage due to thermal stress as described above. High performance.

(Embodiment 2)
Next, a second embodiment will be described. Note that the description of the same parts as those in the first embodiment is omitted or simplified. In the second embodiment, the sizes of the piezoelectric ceramic 210, the vibrating body 220, and the intermediate plate 230 are different from the piezoelectric ceramic 110, the vibrating body 120, and the intermediate plate 130 in the ultrasonic vibrator 100 of the first embodiment, respectively. The rest of the configuration is generally the same as that of the first embodiment, and the description thereof is omitted or simplified.

In the second embodiment, the piezoelectric ceramic 210 generates 1.5 MHz ultrasonic vibration in the thickness direction. The thickness of the piezoelectric ceramic 210 is 1.0 mm. As in the first embodiment, the piezoelectric ceramic 210 has a thermal expansion coefficient of 1.80 × 10 ⁻⁶ (1 / ° C.) and an acoustic impedance of 32.3 × 10 ⁶ (N · s / m ³ ).

The vibrating body 220 has a thickness of 0.2 mm. Similarly to the first embodiment, the vibrating body 220 also has a thermal expansion coefficient of 0.47 × 10 ⁻⁶ (1 / ° C.) and an acoustic impedance of 13.2 × 10 ⁶ (N · s / m ³ ).

The intermediate plate 230 has a thickness of 0.2 mm. Similarly to the first embodiment, the intermediate plate 130 also has a thermal expansion coefficient of 1.40 × 10 ⁻⁶ (1 / ° C.) and an acoustic impedance of 14.3 × 10 ⁶ (N · s / m ³ ).

In the second embodiment, the ratio of the thickness (1.0 mm) of the piezoelectric ceramic 210 to the wavelength λp (2.86 mm) of the ultrasonic wave transmitted through the piezoelectric ceramic 210 is 0.35. The ratio of the thickness (0.20 mm) of the intermediate plate 230 to the wavelength λi (3.10 mm) of the ultrasonic wave transmitted through the intermediate plate 230 is 0.065. Furthermore, the ratio of the thickness (0.20 mm) of the vibrating body 220 to the wavelength λv (3.68 mm) of the ultrasonic wave transmitted through the vibrating body 220 is 0.054. The sum of these ratios is 0.47, which is in the range of 1/2 ± 1/10. For this reason, the piezoelectric ceramic 210, the intermediate plate 230, and the vibrating body 220 can be made to resonate substantially half a wavelength. Therefore, also in this case, the ultrasonic output of the ultrasonic transducer 200 can be improved. In addition, the ultrasonic cleaning machine 250 using the ultrasonic vibration 200 as described above can improve the transmission efficiency of ultrasonic waves while preventing breakage due to thermal stress. Is performance.
In addition, in the ultrasonic vibrator 200 and the ultrasonic cleaner 250, the same parts as those of the first embodiment have the same effects as those of the first embodiment.

The ratio of the thickness of the piezoelectric ceramic 210 to the wavelength λp of the ultrasonic wave transmitted through the piezoelectric ceramic 210 is (0.35), the ratio of the thickness of the intermediate plate 230 to the wavelength λi of the ultrasonic wave transmitted through the piezoelectric ceramic 210 (0.065), and The sum of the ratio (0.054) of the thickness of the vibrating body 220 to the wavelength λv of the ultrasonic wave transmitted through the thickness was not exactly ½ (= 0.5) for the following reason. Conceivable.
First, the influence of the thicknesses (about 0.1 mm each) of the adhesive layers 241 and 242 interposed between the piezoelectric ceramic 210 and the intermediate plate 230 and between the intermediate plate 230 and the vibrating body 220 can be considered. In addition, although the piezoelectric ceramic 210 and the intermediate plate 230, and the intermediate plate 230 and the vibrating body 220 are different from each other in material and characteristics (longitudinal elastic modulus, thermal expansion coefficient, etc.), the piezoelectric ceramic 210 and the intermediate plate 230 are restrained by the adhesive layers 241 and 242. I'm happy. For this reason, it is considered that the sound velocity of the ultrasonic vibration actually transmitted through the piezoelectric ceramic 210, the intermediate plate 230, and the vibrating body 220 becomes a value deviated from the sound velocity when measured in a free state without restraining them. Due to these effects, when the thickness of the intermediate plate 230 and the vibration plate 220 is adjusted so that the ultrasonic output is maximized in the ultrasonic vibrator 200, the ratio of the thickness of the piezoelectric ceramic 210 to the wavelength λp, It is considered that the sum of the ratio of the thickness to the wavelength λi and the ratio of the thickness of the vibrating body 220 to the wavelength λv slightly deviated from 1/2 (0.47 in this example).

(Embodiment 3)
Next, a third embodiment will be described. Note that description of the same parts as those in the first or second embodiment is omitted or simplified. In the third embodiment, the shapes and sizes of the piezoelectric ceramics 110 and 210, the vibrating bodies 120 and 220, and the intermediate plates 130 and 230 are different from those in the first and second embodiments. Other than that, it is substantially the same as in the first and second embodiments.

FIG. 3 shows an ultrasonic transducer 300 according to the third embodiment. The ultrasonic vibrator 300 also includes a piezoelectric ceramic 310, a vibrating body 320, and an intermediate plate 330, and the intermediate plate 330 is interposed between the piezoelectric ceramic 310 and the vibrating body 320.
Among these, the piezoelectric ceramic 310 generates 1 MHz ultrasonic vibration in the thickness direction. The piezoelectric ceramic 310 has a disk shape with a diameter of 20 mm and a thickness of 2.0 mm. This thickness corresponds to ½ of the wavelength λp (4.0 mm) of the ultrasonic wave transmitted through the thickness. The piezoelectric ceramic 310 has a thermal expansion coefficient of 1.80 × 10 ⁻⁶ (1 / ° C.) and an acoustic impedance of 32.3 × 10 ⁶ (N · s / m ³ ).

The vibrating body 320 includes a large-diameter base end portion 320k positioned on the piezoelectric ceramic 310 side and a small-diameter front end portion 320t protruding from the base end portion 320k in the opposite direction to the piezoelectric ceramic 310, and is entirely made of quartz. It is made of glass. The base end portion 320k has a cylindrical shape with a diameter of 35 mm and a thickness of 11 mm. The tip 320t has a cylindrical shape with a diameter of 17 mm and a thickness of 22 mm. Therefore, the total thickness of the vibrating body 320 is 33 mm. The vibrating body 320 has a thermal expansion coefficient of 0.47 × 10 ⁻⁶ (1 / ° C.) and an acoustic impedance of 13.2 × 10 ⁶ (N · s / m ³ ).

Next, the intermediate plate 330 will be described. The intermediate plate 330 has a disk shape with a diameter of 20 mm and a thickness of 0.20 mm. The intermediate plate 330 is formed from a low thermal expansion ceramic. The intermediate plate 330 has a thermal expansion coefficient of 1.40 × 10 ⁻⁶ (1 / ° C.) and an acoustic impedance of 14.3 × 10 ⁶ (N · s / m ³ ).
In the third embodiment, the thickness of the piezoelectric ceramic 310 corresponds to ½ of the wavelength λp of the ultrasonic wave transmitted through the piezoelectric ceramic 310 as in the first embodiment. However, the thicknesses of the vibrating body 320 and the intermediate plate 330 are different from those of the first embodiment, and the sum of the ratios of the ultrasonic waves transmitted through these to the wavelengths λv and λi is 1/2, an integral multiple thereof, or a value close to these values. It is not.

  Such an ultrasonic transducer 300 also has a thermal stress generated between the piezoelectric ceramic 310 and the intermediate plate 330 or the intermediate plate 330 even when the ultrasonic transducer 300 is exposed to a high temperature in its use environment or manufacturing process. The thermal stress generated between the piezoelectric ceramic and the vibrating body 320 is smaller than that of the conventional ultrasonic vibrator that directly joins the piezoelectric ceramic and the vibrating body. Therefore, it is possible to prevent the ultrasonic vibrator 300 from being damaged such as the piezoelectric ceramic 310 and the vibrating body 320 being cracked due to thermal stress.

  The acoustic impedance of the intermediate plate 330 is a value between the acoustic impedance of the piezoelectric ceramic 310 and the acoustic impedance of the vibrating body 320. For this reason, compared with the case where the piezoelectric ceramic 310 and the vibrating body 320 are directly joined, the difference in acoustic impedance between the piezoelectric ceramic 310 and the intermediate plate 330 and between the intermediate plate 330 and the vibrating body 320 is reduced, and the interface between them. The reflection of the ultrasonic wave at is suppressed, and the ultrasonic wave can be transmitted efficiently. Therefore, this ultrasonic transducer 300 can also improve the conduction efficiency and radiation efficiency of ultrasonic waves as compared with the conventional case.

Specifically, the ultrasonic output of the ultrasonic transducer 300 of the third embodiment is 40 mV to 50 mV. On the other hand, in the conventional ultrasonic vibrator in which a stainless mesh having a thickness of about 0.2 mm is interposed between the piezoelectric ceramic 310 and the vibrating body 320 instead of the intermediate plate 330, the ultrasonic output is 30 mV. There was only ~ 40mV.
In addition, in the ultrasonic transducer 300, the same parts as those in the first or second embodiment have the same effects as those in the first or second embodiment.

Next, an ultrasonic cleaner 350 according to the third embodiment will be described with reference to FIG. The ultrasonic cleaning machine 350 is for cleaning the work W by irradiating the work W such as a silicon chip with ultrasonic waves.
The ultrasonic cleaner 350 includes the ultrasonic vibrator 300 and a guide 360 that fixes the ultrasonic vibrator 300. A through hole 360c is formed in the guide 360. And the front-end | tip part 320t of the vibrating body 320 among the ultrasonic transducer | vibrators 300 is penetrated by this through-hole 360c. Further, the base end portion 320 k of the vibrating body 320 and the guide 360 are fixed via a packing 370.

Such an ultrasonic cleaning machine 350 has high reliability because the ultrasonic transducer 300 can improve the ultrasonic transmission efficiency while preventing damage due to thermal stress as described above. High performance.
In addition, also in the ultrasonic cleaning machine 350, the same parts as those in the first or second embodiment have the same operational effects as those in the first or second embodiment.

In the above, the present invention has been described with reference to the embodiments. However, the present invention is not limited to the above-described first to third embodiments, and can be applied with appropriate modifications without departing from the gist thereof. Not too long.
For example, in the first to third embodiments, the case where there is one intermediate plate 130 interposed is shown, but a plurality of intermediate plates may be interposed.

5 is an explanatory diagram showing an ultrasonic transducer according to Embodiments 1 and 2. FIG. It is explanatory drawing which shows the ultrasonic cleaning machine which concerns on Embodiment 1,2. 6 is an explanatory diagram showing an ultrasonic transducer according to Embodiment 3. FIG. It is explanatory drawing which shows the ultrasonic cleaning machine which concerns on Embodiment 3. FIG.

Explanation of symbols

100, 200, 300 Ultrasonic vibrators 110, 210, 310 Piezoelectric ceramics 120, 220, 320 Vibrating bodies 130, 230, 330 Intermediate plates 141, 142, 241, 242, 341, 342 Adhesive layers 150, 250, 350 Ultrasonic waves washing machine

Claims (5)

An ultrasonic vibrator comprising piezoelectric ceramics and a vibrator that transmits ultrasonic waves generated by the piezoelectric ceramics,
One or a plurality of intermediate plates interposed between the piezoelectric ceramic and the vibrating body,
The thermal expansion coefficient has a value between the thermal expansion coefficient of the piezoelectric ceramic and the thermal expansion coefficient of the vibrator, and
An ultrasonic transducer comprising one or more intermediate plates whose acoustic impedance has a value between the acoustic impedance of the piezoelectric ceramic and the acoustic impedance of the vibrating body. The ultrasonic transducer according to claim 1,
The thickness of the piezoelectric ceramic corresponds to 1/2 of the wavelength λp of the ultrasonic wave transmitted through the piezoelectric ceramic,
The sum of the ratio of the thickness of the intermediate plate to the wavelength λi of the ultrasonic wave transmitted through this and the ratio of the thickness of the vibrator to the wavelength λv of the ultrasonic wave transmitted through the thickness within a range of 1/2 ± 1/10. An ultrasonic transducer. The ultrasonic transducer according to claim 1,
The ratio of the thickness of the piezoelectric ceramic to the wavelength λp of the ultrasonic wave transmitted through this, the ratio of the thickness of the intermediate plate to the wavelength λi of the ultrasonic wave transmitted through this, and the wavelength of the ultrasonic wave transmitted through the thickness of the vibrating body λv The ultrasonic transducer whose sum with the ratio to is in the range of 1/2 ± 1/10. The ultrasonic transducer according to any one of claims 1 to 3,
The vibrating body is made of quartz glass,
The intermediate plate is an ultrasonic vibrator made of low thermal expansion ceramics. An ultrasonic cleaner provided with the ultrasonic transducer according to any one of claims 1 to 4.

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