JPH074575B2 - Piezoelectric ceramic element for torsion type vibrator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to generation of a torsional mode of a composite oscillator used by generating a torsional vibration mode in an ultrasonic motor, an ultrasonic processing machine, a mechanical filter, or the like. The present invention relates to a piezoelectric vibration element that is a source.

[Prior Art] Conventionally, a piezoelectric vibrating element for this kind of application is configured so as to change the thickness-shear vibration mode of piezoelectric ceramics into a torsion mode of a rigid body that connects the piezoelectric vibration element. It is orthogonal to the axis.

7 (a) and 7 (b) are diagrams showing the structure of an ideal piezoelectric ceramic element as a drive source of a torsion type piezoelectric vibrator, in which concentric arrows are formed around the central axes of the piezoelectric ceramics 51, 51 '. The polarization axis shown by 52, 52 'passes through.
However, the structure shown in FIG. 7 is not possible in the piezoelectric ceramic due to the polarization treatment, and some vibrators have been proposed that are similar to the structure shown in FIG.

8 and 9 are perspective views showing a piezoelectric vibration element similar to the piezoelectric vibration element shown in FIG. The piezoelectric torsion type vibrator realized by the division method shown in FIGS. 8 (a) and 8 (b) consists of one disc 61 or a ring 61 'composed of several divided pieces. Polarization axis 62, indicated by an arrow
And 62 'are connected to form an approximate structure shown in FIG.

Further, FIG. 9 shows an ideal configuration of the piezoelectric torsion type vibrator shown in FIG.
(A) shows the state in which the electrodes 72 for polarization are radially formed on the ring 71, and (b) schematically shows how the electric field is applied and the lines of electric force at the time of polarization. (C) is a cross-sectional view of a part showing a state in which the electrodes polarized in (b) are removed, new split electrodes are formed between the original electrodes, and the wires are connected so that sliding vibration in the same direction occurs. There is. As shown in FIG. 8, some radial polarization electrodes 72, 72 are formed on the upper and lower surfaces of a disk or ring, and polarization treatment is performed separately on the front and back sides to form two sets of electrode groups 72a. , 72b are divided electrodes. In this way, the polarization component orthogonal to the driving electric field is obtained, and the configuration of FIG. 7 is approximately realized.

[Problems to be Solved by the Invention] However, in the case of the conventional element division method of FIG. 8, 1) the polarization and processing steps are complicated and the cost is increased, and 2) the characteristics are easily influenced by the bonding conditions. .
3) The electromechanical conversion efficiency is low. It had a defect such as.

Further, in the case of the electrode division method shown in FIG. 9, 1) the lines of electric force are concentrated on the surface during polarization, so the polarization is large in the surface layer and small in the middle part, and the electromechanical conversion efficiency is low. 2)
It is necessary to divide the drive electrode, and there is a drawback that the design becomes complicated depending on how to take out the electric terminals of the vibrator.

Therefore, the technical problem of the present invention is to eliminate the above drawbacks, the polarization and processing steps are simple, can be manufactured at low cost, the characteristics depending on the adhesion conditions depending on the manufacturing conditions such as bonding conditions. An object of the present invention is to provide a piezoelectric ceramic element for a torsion type vibrator which is not affected by the above and has a high electromechanical conversion efficiency and the like and which is simple in design.

[Means for Solving the Problems] According to the present invention, a plurality of first divided electrodes and a plurality of second divided electrodes which are radially divided into a first surface and a second surface of the piezoelectric ceramic ring which face each other. The divided electrodes are provided, and the first lines of the first divided electrodes and the lines of the second divided electrodes are arranged such that the lines of electric force have a constant inclination angle with respect to the thickness direction.
Select the combination of the split electrode and the second split electrode of
After the polarization treatment is divided into a plurality of times, the plurality of first divided electrodes are electrically coupled to each other to form a first entire surface electrode, and the plurality of second divided electrodes are electrically coupled to each other. Second
A piezoelectric ceramic element for a torsional vibrator, which is characterized in that the entire surface of the electrode is used.

[Operation] In the piezoelectric ceramic element for a torsion type vibrator of the present invention, the first divided electrode and the second divided electrode radially divided into the first surface and the second surface facing each other to the piezoelectric ceramic ring. In addition, the combination of the first divided electrode and the second divided electrode is selected so that the lines of electric force between the first divided electrode and the second divided electrode have a constant inclination angle with respect to the thickness direction. Then, the plurality of divided electrodes are subjected to polarization treatment, the plurality of first divided electrodes are electrically coupled to each other to form a first full surface electrode, and the plurality of second divided electrodes are electrically coupled to each other to form a first 2 electrodes on the entire surface.

When an AC voltage having a frequency equal to the resonance frequency of the piezoelectric ceramic ring is applied between the first full surface electrode and the second full surface electrode, the polarization direction of the piezoelectric ceramic ring and the electric field direction form a constant angle. Cross. Therefore, torsional vibrations are generated which are distorted in opposite directions along the circumferential direction of the first surface and the second surface of the piezoelectric ceramic ring.

EXAMPLES The present invention will be described in detail below with reference to the drawings.

FIG. 7 is a diagram showing an ideal polarization state as a piezoelectric element of a torsion mode oscillator.

However, in reality, polarization as shown in FIG. 7 is impossible for a single disk or ring. Until now,
FIG. 8 and FIG. 9 show a conventional system which realizes the state of FIG. 7 approximately.

FIG. 1 is a diagram showing a piezoelectric ceramic element for a torsion type vibrator according to an embodiment of the present invention. FIG. 2 is a diagram in which the circumferential direction of the piezoelectric ceramic element for a torsion type vibrator of FIG. 1 is linearly developed. In FIG. 2, the piezoelectric A ₁ the first divided electrode on the upper surface of the ceramic element 10, A _2, ..., ₁ to A _n second electrode on the bottom surface opposite thereto B, B _2, ..., B _{Let n} . Electrode A ₃
And when only a DC voltage is applied at a constant temperature between B _1,
Polarization occurs in the direction of arrow 13.

Next, between the electrodes A ₄ and B _2, between the electrodes A ₅ and B _3, between A ₁ and B _n-1 ,
Alternatively, when a DC electric field is sequentially applied between the first divided electrode A _{k + 2} and the second divided electrode B _k (where k is a natural number) such as between the electrodes A ₂ and B _n , the electrode surface and the electrode surface are kept constant. The tilted polarization can be processed sequentially in the circumferential direction. When a DC electric field is applied between electrodes A ₃ and B ₁ during polarization,
When an electric field is applied between the electrode A ₄ adjacent to A ₃ and the electrode B ₂ adjacent to the electrode B ₁ , the directions of the lines of electric force are slightly changed, and the angles of the polarization directions are nonuniform. However, when a DC voltage is applied between the electrodes A ₃ and B ₁ , the polarization between the electrodes A ₈ and B ₆ is hardly affected. Therefore, the polarization processing can be performed in parallel at the same time with some intervals.

FIG. 3 is a diagram showing an example of parallel processing of the first and second electrodes. In this figure, the first divided electrodes 1,1 ′, 1 ″, 1
Can apply a far voltage at the same time. Then, the first divided electrodes 2, 2 ′, 2 ″, 2 and the sequential division can be performed as indicated by the arrow 15.

It is well known that the thickness stumbling vibration mode occurs when there is a polarization axis with a certain inclination angle with the electrode surface ("Piezoelectric ceramic material" Tetsuro Tanaka, Kiyoshi Okazaki et al., Edited by Gakudensha 1973). Therefore, when a metal rod having an appropriate size is adhered to both sides to form a Langevin oscillator, it resonates at the fundamental frequency of the torsion mode.

FIG. 4 is a diagram showing how sliding displacement occurs when an AC voltage is applied to the structure of FIG. In this figure, when the AC power supply 16 is connected between the first and second full-surface electrodes 17 and 18 on the upper and lower surfaces, distortion occurs in the vicinity of the upper and lower surfaces in directions opposite to each other along the circumference.

FIG. 5 shows the shape of the piezoelectric ceramics in the example, and various matters related to Table 1 are entered.

Next, as shown in FIG. 6, the aluminum columns 21,2
After bonding 1'on both sides with a conductive adhesive, it was connected to an AC power supply 23, and the basic performance as a torsional oscillator was confirmed.

The results are shown in Table 2.

[Effects of the Invention] As described above, according to the present invention, there is provided a piezoelectric ceramic element for a torsional vibrator, which has advantages such as a simple manufacturing process, no influence of bonding conditions, and high electromechanical filling efficiency. Offering is now possible.

[Brief description of drawings]

FIG. 1 is a diagram showing the basic configuration of the present invention. The electrodes on the upper and lower surfaces of the ring-shaped piezoelectric ceramic are divided radially, and the polarization is selected by selecting the upper and lower electrode groups and the polarization axis with respect to the electrode surface. Are configured to form a constant angle. FIG. 2 is a diagram showing a polarization method for realizing the configuration of FIG. 1, and the positions of the electrodes to which a voltage is applied are vertically displaced. FIG. 3 is a diagram provided for explaining the polarization processing at the same time between the separated positions that do not interfere with each other in order to efficiently perform the polarization of FIG. FIG. 4 is a diagram showing how sliding displacement occurs when an AC voltage is applied to the structure of FIG. FIG. 5 is a diagram showing the shape of the piezoelectric ceramic ring manufactured in the example, and the dimensions are also shown. FIG. 6 is a diagram showing main dimensions when a torsional oscillator is constructed by using the piezoelectric ceramic ring of FIG. FIGS. 7 (a) and 7 (b) are diagrams showing the structure of an ideal piezoelectric ceramic element as a drive source of a torsion type piezoelectric vibrator. FIGS. 8 (a) and 8 (b) are diagrams in which the configuration of FIG. 7 is approximately realized by a division method, and in the figure, the disk (a) and the ring (b) are shown divided into four parts. . FIG. 9 shows the structure of FIG. 1 realized by a split electrode method. FIG. 9A shows a state in which electrodes 2 for polarization are radially formed on a ring 1, and FIG. 9B shows polarization. The method of applying an electric field and the state of electric lines of force are schematically shown in (c), the electrodes polarized in (b) are removed, and a new divided electrode is formed between the original electrodes. FIG. 6 is a partial view showing a state in which the wires are connected so that slip vibration occurs. Figure _{A 1, A 2, ...,} A n are first divided _{electrode, B 1, B 2, ...} , B n
Is a second divided electrode, 10 is a piezoelectric ceramic element, 13 is an arrow, 1,1 ', 1 ", 1 and 2,2', 2", 2 are corresponding parts of the first divided electrode, 15 is an arrow, 16 is an AC power supply, 17 is a first full-surface electrode, 18 is a second full-surface electrode, 21 and 21 'are aluminum cylinders, 23 is an AC power supply, 51 and 51' are piezoelectric ceramics, 52,
52 'is an arrow indicating the polarization axis, 61 is a disc, 61' is a ring, 6
2, 62 'are arrows showing the polarization axis, 71 is a ring, 72 is a polarization electrode, and 72a, 72b are front and back electrode groups.

Claims (1)

[Claims] 1. A plurality of first portions radially divided into a first surface and a second surface of a piezoelectric ceramic ring which face each other.
A plurality of divided electrodes and a plurality of second divided electrodes,
The combination of the first divided electrode and the second divided electrode is selected so that the lines of electric force between the divided electrode and the second divided electrode have a constant inclination angle with respect to the thickness direction. After the polarization treatment is divided into a plurality of times, the plurality of first divided electrodes are electrically coupled to form a first entire surface electrode, and
A piezoelectric ceramic element for a torsion type vibrator, characterized in that the plurality of second divided electrodes are electrically coupled to form a second whole surface electrode.