JPH0888899A - Ultrasonic vibrator - Google Patents

Abstract

PURPOSE: To provide an ultrasonic vibrator in which the adjustment of a drive circuit is easy and no unevenness is produced in ultrasonic radiation. CONSTITUTION: Piezoelectric ceramic 1 is composed of piezoelectric ceramic, formed in a plate shape and polarized in the plate thickness direction. On the surface of this piezoelectric ceramic 1, split electrodes 21, 22 and 23 roughly and uniformly divided into three are formed. On the rear surface, rear electrodes are formed almost all over the surface. By connecting these surface electrodes (the same polarity split electrodes) and rear electrodes with a lead wire and supplying ac power of a prescribed frequency by an oscillator, an ultrasonic vibrator is driven and a desired ultrasonic wave is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic vibrator used in an ultrasonic cleaning apparatus and the like, and more particularly to an ultrasonic vibrator which efficiently radiates ultrasonic waves by vibrating thickness.

[0002]

2. Description of the Related Art Ultrasonic oscillators used in ultrasonic cleaning devices include piezoelectric Langevin type oscillators and piezoelectric bimorph type oscillators. Each of these ultrasonic transducers is attached to the bottom surface, side surface, etc. of the cleaning tank and is used for ultrasonic cleaning by radiating ultrasonic waves to the liquid or the like in the cleaning tank. However, these ultrasonic transducers have a relatively low frequency, which is effective for removing dirt of relatively large particles, but has a problem that it is not effective for dirt of fine particles. As an ultrasonic vibrator that solves such a problem, an ultrasonic vibrator that vibrates a thickness-based vibration having a higher frequency (for example, 1 MHz or more) has been put into practical use.

FIG. 5 is a plan view of a conventional ultrasonic vibrator that vibrates in a thickness system, and FIG. 6 is a front view of the vibrator shown in FIG. Excitation electrodes 91 and 92 are independently formed on the front and back surfaces of the piezoelectric ceramic plate 8. When alternating electric power of a predetermined frequency is supplied from the oscillator G to these excitation electrodes, this ultrasonic vibrator causes mechanical vibration due to the piezoelectric effect,
Ultrasonic waves are emitted from the plate surface. The thickness type vibration has a relatively high frequency, and such an ultrasonic vibrator can remove dirt of fine particles.

[0004]

As described above, the thickness type vibration has a relatively high frequency, and such an ultrasonic vibrator can remove dirt on fine particles. Cleaning equipment is becoming larger in order to increase the size of wafers and improve productivity, such as semiconductor cleaning equipment.Accordingly, by increasing the number of transducers or increasing the size of ultrasonic transducers It corresponded to this. However, increasing the number of oscillators requires more work to attach them to the cleaning tank, and the individual electrical characteristics may differ to some extent due to variations in piezoelectric ceramics, making it compatible with the drive circuit (oscillation circuit). Had to take. When the ultrasonic transducer is made larger, the ultrasonic transducer is moved to the ultrasonic transducer as shown in the data (schematically shown) of the vibration displacement state of the ceramic plate surface of FIG. 7 measured by the laser Doppler displacement measuring device. While sufficient ultrasonic vibration is obtained on the surface of the ceramic plate near the power supply position, the vibration displacement is attenuated as the distance from this position increases. The unevenness of ultrasonic radiation on the surface of the piezoelectric ceramic plate causes uneven cleaning in cleaning,
This has led to a reduction in the cleaning ability of the ultrasonic cleaning device.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an ultrasonic transducer in which the driving circuit can be easily adjusted and ultrasonic radiation unevenness does not occur. .

[0006]

In order to solve the above-mentioned problems, an ultrasonic transducer according to the present invention has excitation electrodes formed on the front and back surfaces of a piezoelectric ceramics plate, and ultrasonic waves are transmitted from the plate surface by thickness-based vibration. In an ultrasonic transducer that emits
The excitation electrode is formed by forming a full-scale electrode on the back surface and arranging a plurality of divided electrodes of a predetermined area on the front surface, and applying an alternating electric field of the same polarity to each of these divided electrodes,
It is characterized in that an alternating electric field of another pole is applied to the back surface electrode.

[0007]

According to the present invention, it is possible to obtain a plurality of independent vibration regions between each of the divided electrodes on the front surface and the entire electrode on the back surface, and the vibration regions vibrate in the same phase. As a result, ultrasonic vibration can be radiated from the entire surface of the piezoelectric ceramic plate without unevenness.

In the product of the present invention having the structure shown in FIG. 3, a frequency of 1 MHz is applied between the terminals obtained by connecting lead wires to the divided electrodes on the front surface and commonly connecting the lead wires to the terminals obtained from the lead wires connected to the entire surface electrodes on the back surface. The thickness system vibration was excited by inputting the alternating electric power of, and the vibration displacement state of the piezoelectric ceramics plate surface at this time was measured by the laser Doppler measuring device. FIG. 8 schematically shows this measurement result, but it can be understood that sufficient vibration displacement is measured on the entire surface of the piezoelectric ceramic, and sufficient ultrasonic waves are radiated from the entire surface of the ceramic plate.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view seen from the front surface of the ultrasonic transducer, and FIG. 2 is a perspective view seen from the back surface. FIG. 1 also shows the connection state with the oscillator G. Piezoelectric ceramics 1
Is made of piezoelectric ceramics such as barium titanate-based ceramics or titanium / zirconate-based ceramics, and is formed into a plate shape and polarized in the thickness direction of the plate. Split electrodes 21, 22 and 23, which are substantially evenly divided into three, are formed on the front surface of the piezoelectric ceramic 1, and a back surface electrode 20 is formed on the back surface almost all over.
Are formed. Usually, as the above-mentioned electrode, a polarization electrode used for polarization of ceramics is often used as the excitation electrode as it is. In this case, except for the electrode formation portion,
Not polarized. In addition, there is no practical problem even if the entire surface of the piezoelectric ceramic is polarized and then the above-mentioned electrode for excitation is newly formed. Lead wires are connected to the front surface electrodes (divided electrodes having the same polarity) and the back surface electrode, and an ultrasonic oscillator is driven by supplying alternating power of a predetermined frequency by an oscillator to obtain a desired ultrasonic wave.

A second embodiment of the present invention will be described with reference to the drawings. FIG. 3 is a perspective view seen from the surface of the ultrasonic transducer. Note that the drawing viewed from the back has the same configuration as that of FIG. Piezoelectric ceramics 1
Is made of piezoelectric ceramics such as barium titanate-based ceramics or titanium-zirconate-based ceramics, and is formed into a plate shape and polarized in its thickness direction. Split electrodes 26, 27, 28, which are substantially evenly divided into three, are formed on the front surface of the piezoelectric ceramic 1, and a back surface electrode 24 (not shown) is formed on almost the entire back surface thereof. A part of this back electrode is drawn out to the periphery of the front surface to form a peripheral electrode 25. Split electrodes 26, 27 having the same polarity on the surface
The lead wire derived from 28 is connected in common, two lead wires are connected to the peripheral electrode connected to the back surface electrode, and the ultrasonic transducer is driven by supplying alternating electric power by the oscillator to obtain a desired ultrasonic wave. .. The presence of the surrounding electrodes has the advantage that both electrodes can be electrically connected on one surface. The number of lead wires connected to the peripheral electrodes is not limited to two, and may be one or more.

A third embodiment of the present invention will be described with reference to the drawings. FIG. 4 is a plan view of the surface of the ultrasonic transducer. The piezoelectric ceramics 3 are made of piezoelectric ceramics such as barium titanate-based ceramics or titanium-zirconate-based ceramics, and are formed into a substantially square plate shape and polarized in the thickness direction.
Split electrodes 41, 42, 43, 44, which are substantially evenly divided into four, are formed on the surface of the piezoelectric ceramic 1, and a back surface electrode (not shown) is formed on almost the entire back surface thereof. . A part of this back electrode is drawn out to the periphery of the front surface to form a peripheral electrode 40. In such a configuration of electrode arrangement, electrode connection similar to that of the second embodiment is performed, and the ultrasonic oscillator is driven by supplying alternating electric power by the oscillator to obtain a desired ultrasonic wave.

[0012]

According to the present invention, it is possible to obtain a plurality of independent vibration regions between each of the divided electrodes on the front surface and the entire electrode on the back surface, and the vibration regions vibrate in the same phase. As a whole, ultrasonic vibration can be radiated uniformly from the entire surface of the piezoelectric ceramic plate. Therefore, for example, during ultrasonic cleaning, an ultrasonic vibrator that does not cause cleaning unevenness and does not reduce the cleaning capability of the ultrasonic cleaning device is obtained, and the drive circuit is also considered without considering the variation of the piezoelectric ceramics. It is possible to obtain an ultrasonic transducer in which the (oscillation circuit) can be easily matched.

[Brief description of drawings]

FIG. 1 is a perspective view showing a first embodiment of the present invention.

FIG. 2 is a perspective view showing a first embodiment of the present invention.

FIG. 3 is a perspective view showing a second embodiment of the present invention.

FIG. 4 is a plan view showing a third embodiment of the present invention.

FIG. 5 is a plan view showing a conventional example.

FIG. 6 is a front view showing a conventional example.

FIG. 7 is a diagram showing comparison data.

FIG. 8 is a diagram showing comparison data.

[Explanation of symbols]

1, 3, 8 Piezoelectric ceramics 21, 22, 23, 26, 27, 28, 41, 42 ,.
43,44 Front split electrode 20 Back electrode 25,40 Peripheral electrode G Oscillator

Claims (1)

[Claims] 1. An ultrasonic transducer comprising excitation electrodes formed on the front and back surfaces of a piezoelectric ceramics plate, and ultrasonic waves being radiated from the plate surface due to thickness-based vibration, wherein the excitation electrodes form full-face electrodes on the back surface. At the same time, a plurality of divided electrodes having a predetermined area are disposed on the front surface, and the divided electrodes are supplied with alternating electric power of the same polarity, and the rear surface electrode is supplied with alternating electric power of other poles. Ultrasonic transducer.