JPH072229B2 - Piezoelectric elliptical motion oscillator - Google Patents

Description

TECHNICAL FIELD The present invention relates to a small motor used in electronic equipment,
In particular, it relates to a piezoelectric elliptical motion oscillator used for a small ultrasonic motor having a small rotor diameter.

(Prior Art) Generally, an ultrasonic motor is
It has advantages such as high torque at low rotation, stop holding force, and little electromagnetic noise, and is used for autofocus of cameras and power motors for automobiles. FIG. 9 is a schematic diagram showing the structure of a conventional piezoelectric elliptical motion oscillator used in a small ultrasonic motor, that is, each column oscillator 100. Two adjacent faces of a metal prism 120 having a substantially square cross section are shown. , Piezoelectric ceramic thin plates 121a, 1 each having electrodes formed and polarized in the thickness direction
21b is glued.

The lead terminals 122a and 122b are drawn out from the surface electrodes of the piezoelectric ceramic thin plates 121a and 121b, and the common ground terminal 123 is drawn out from the metal prism 120. Since the cross-sectional shape of the metal prism 120 is substantially square, the metal prism 120 flexurally vibrates in a direction orthogonal to each other at substantially the same resonance frequency.

Therefore, when AC voltages having frequencies equal to the resonance frequency and phases different by 90 ° are applied to the lead terminals 122a-123 and 122b-123, both ends of the metal prism 120 vibrate circularly or elliptically. FIG. 10 shows the prismatic vibrator 10 shown in FIG.
It is a figure which shows the structural example of the ultrasonic motor which used 0. Discs 124a and 124b are attached to both ends of the prismatic oscillator 100, and support pins 125a and 125b are formed at the vibration nodes of the prismatic oscillator 100. The prismatic oscillator 100 is stabilized by the support pins 125a and 125b. Supported by. The discs 124a, 124b provided at both ends of the prismatic vibrator 100 are inserted into the cavities of the cup-shaped rotating rollers 126a, 126b rotatably supported by the rotating shaft,
It is in pressure contact with the inner wall of the cavity.

Therefore, when the end of the prismatic vibrator 100 vibrates circularly or elliptically, the cup-shaped rotating rollers 126a and 126b are rotated.

(Problems to be Solved by the Invention) However, in the conventional prismatic elliptical motion oscillator as shown in FIG. 9, since the oscillator is a prism having a square cross section, the resonance frequencies of bending modes in directions orthogonal to each other. In order to accurately match with each other, it is necessary to strictly control the machining accuracy of the prism.

Further, when the piezoelectric ceramic thin plate is bonded to the metal prism, the bonding state varies widely. Further, in the case of constructing an ultrasonic motor having a structure as shown in FIG. 10, it is necessary to add a disc or the like to both ends of the metal prism in order to improve the contact state with the cup-shaped rotating roller. It had drawbacks. Therefore, a technical object of the present invention is to provide a piezoelectric elliptical motion oscillator that does not require a contact member such as a disk and is easy to assemble without being restricted by processing accuracy.

(Means for Solving the Problems) According to the present invention, a plurality of electrode pairs are provided on the outer peripheral surface of the piezoelectric ceramic cylinder at predetermined intervals in parallel with the length direction, and at least one of the electrode pairs is provided. DC voltage is applied to the piezoelectric ceramics column to perform polarization treatment in a direction perpendicular to the longitudinal direction, and AC voltages having different phases are applied to two of the electrode pairs to obtain the piezoelectric ceramics. A piezoelectric elliptical motion oscillator is obtained which is capable of exciting an elliptical motion including a circle at both ends of a cylinder.

Here, in the present invention, it is desirable that the alternating currents applied to these divided electrode pairs have a 90 ° phase difference.

According to the present invention, first and second piezoelectric ceramic discs, a first metal cylinder sandwiched between one ends of these first and second piezoelectric ceramic discs, and these first and second piezoelectric ceramic discs. Two
A piezoelectric elliptical motion oscillator having second and third metal cylinders respectively provided at the other end of the first piezoelectric ceramic disc, wherein the first piezoelectric ceramic disc is the first piezoelectric ceramic disc. The second piezoelectric ceramic discs are polarized so as to be opposite to each other in the thickness direction with a first boundary surface that is divided into two in the direction along the central axis of the plate as a boundary, and the second piezoelectric ceramic disc is the piezoelectric ceramic disc. The plate is divided into two along the central axis of the plate, and is polarized so as to be opposite to each other in the thickness direction with the second boundary surface inclined at a predetermined angle from the first boundary surface as a boundary. The first metal cylinder can be used as a common ground, and alternating voltages having different phases can be applied to the second and third metal cylinders to excite elliptical motion including circles at both ends of the piezoelectric elliptical motion oscillator. A piezoelectric elliptical motion oscillator characterized by It is.

According to the present invention, the first and second disk-shaped piezoelectric vibrators,
A first metal cylinder sandwiched between one ends of the first and second disk-shaped piezoelectric vibrators and a first metal cylinder provided at the other ends of the first and second disk-shaped piezoelectric vibrators, respectively. A piezoelectric elliptical motion oscillator having a second and a third metal cylinder, wherein the first disk-shaped piezoelectric vibrator is 2 in a direction along a central axis of the first disk-shaped piezoelectric vibrator. Polarizations are made so as to be opposite to each other in the thickness direction with the first boundary surface to be divided and the second boundary surface divided into two in the thickness direction as boundaries, and the second disk-shaped piezoelectric vibrator is A third boundary surface which is divided into two parts in a direction along the central axis of the second disk-shaped piezoelectric vibrator and which is inclined at a predetermined angle with the first boundary surface, and a second part which is divided into two parts in the thickness direction. Are polarized so as to be opposite to each other in the thickness direction with the boundary surface of the first and second metal columns as a common ground. Then, by applying alternating voltages of different phases to the second and fourth boundary surfaces, it is possible to excite an elliptic motion including a circle at both ends of the piezoelectric elliptical motion oscillator. An elliptical motion oscillator is obtained.

Here, in the present invention, it is desirable that the polarization boundary lines of the piezoelectric ceramic disk are arranged so as to intersect each other at right angles.

According to the present invention, the first and second cylindrical piezoelectric vibrators,
A first metal cylinder sandwiched between one ends of the first and second cylindrical piezoelectric vibrators, and second and second cylinders provided at the other ends of the first and second cylindrical piezoelectric vibrators, respectively. 3 is a piezoelectric elliptical motion oscillator in which a metal cylinder of 3 is fixed by a penetrating member, and the first cylindrical piezoelectric oscillator is divided into two in a direction along the central axis of the first cylindrical piezoelectric oscillator. The second cylindrical piezoelectric vibrator is polarized so as to be opposite to each other in the thickness direction with the first boundary surface and the second boundary surface divided in two in the thickness direction as boundaries. A second boundary surface is divided into two in the direction along the central axis of the two cylindrical piezoelectric vibrators and a third boundary surface inclined at a predetermined angle from the first boundary surface and a fourth boundary surface divided into two in the thickness direction. And are polarized so as to be opposite to each other in the thickness direction, and the first and second boundary surfaces are respectively polarized. A second intermediate terminal plate, said first
It is possible to excite an elliptic motion including circles at both ends of the piezoelectric elliptical motion oscillator by applying alternating voltages of different phases to the terminal plate with the first, second, and third metal cylinders as a common ground. A piezoelectric elliptic motion oscillator characterized by the above is obtained. Here, in the present invention, it is desirable that the piezoelectric ceramic perforated discs are arranged so that the directions of the polarization boundary lines intersect each other at a right angle.

(Operation) The operation of the present invention will be described.

The piezoelectric elliptical motion oscillator of the present invention is provided with a plurality of pairs of divided electrodes on a cylinder at positions that equally divide the circumferential direction, apply a DC voltage to the electrode pairs, and subject the divided electrodes to a polarization treatment. When at least two pairs of AC voltages are applied, each electrode vibrates in a direction substantially perpendicular to the applied direction. These electrodes are formed so that the AC voltage application directions cross each other, and
When an AC voltage is applied so as to have a phase difference within a range of °, both ends of the cylindrical vibrator perform elliptical vibration including a circle according to the phase difference.

In the piezoelectric elliptical motion oscillator of the present invention, a plurality of piezoelectric oscillators are interposed between a plurality of conductors, and the polarization boundary surfaces of the piezoelectric oscillators are made to intersect with each other. When an alternating current having a phase difference is applied, both ends of the piezoelectric elliptical motion oscillator make an elliptical motion including a circle.

(Example) The Example of this invention is described with reference to drawings.

Example 1 Example 1 of the present invention will be described.

FIG. 1 is a perspective view of a piezoelectric elliptical motion oscillator according to a first embodiment of the present invention, in which electrodes 2, 3 are arranged in parallel with the length direction at positions on a side surface of a piezoelectric ceramic cylinder 1 in four circumferential directions. , 4,5 are formed. The ratio of the width of one electrode to the dimension without electrode is about 1: 1. FIG. 2 is a sectional view of a piezoelectric ceramic cylinder, and is an explanatory view of a state in which distortion occurs due to a polarization direction and a driving voltage. FIG. 2 (a) is a diagram showing the direction of polarization when a voltage is applied with the electrodes 2 and 4 being positive and the electrodes 3 and 5 being negative, and the direction of polarization is indicated by broken line arrows.

2 (b) is a piezoelectric ceramic cylinder polarized as shown in FIG. 2 (a), in which electrodes 2, 3 and 4, 5 are connected to each other, the electrodes 2, 3 are positive, and the electrodes 4, 5 are negative. It shows the occurrence of distortion in the cross-sectional direction of the cylinder when a voltage is applied.

As shown by the solid line arrow in FIG.
Since a voltage is applied in the direction from the electrode 5 to the electrode 5 and in the direction from the electrode 3 to the electrode 4, expansion strain occurs between the electrodes 2 and 5, and contraction strain occurs between the electrodes 3 and 4. .
When a cross-sectional strain occurs in the direction shown in FIG. 2 (b), the piezoelectric ceramic cylinder 1 extends in the length between the electrodes 3 and 4, and at the same time, between the electrodes 2 and 5. The length of the part shrinks. As a result, the piezoelectric ceramics 1 bends so that the lower side bulges in FIG. 2 (b).
When the polarity of the applied voltage is reversed, the piezoelectric ceramic cylinder 1 bends in the opposite direction.

FIG. 3 is an explanatory view of a vibrating state when an AC voltage is applied to the piezoelectric ceramic cylinder 1 shown in FIG.
When an AC voltage having a frequency equal to the resonance frequency of the vibrator is applied between the electrodes and the electrodes 4 and 5, bending resonance occurs in the direction of arrow 6 as shown in FIG.

If electrodes 2 and 5 and electrodes 3 and 4 are connected to each other and an AC voltage having a frequency equal to the resonance frequency of the vibrator is applied,
The bending vibration direction is perpendicular to the vibration direction shown in FIG. Therefore, by shifting the phase of the flexural vibration in the two directions shown above by 90 °, specifically by shifting the phase of each drive voltage by 90 °, the piezoelectric ceramic cylinder 1 is provided with the two ends shown in FIG. It is possible to excite circular vibration or elliptical vibration as shown in b).

Example 2 Example 2 of the present invention will be described.

FIG. 4 (a) is a perspective view showing an example of the structure of the piezoelectric elliptical motion oscillator according to the second embodiment of the present invention. In FIG. 4 (b), the piezoelectric ceramic disks 11 and 12 are boundary surfaces that are divided into two in the direction along the center, respectively, and the polarization directions of two substantially symmetrical regions on both sides of this polarization boundary line are in the thickness direction. They are polarized so that they are in opposite directions. Bound each other
A metal cylinder 14 is sandwiched between piezoelectric ceramic disks 11 and 12 tilted by 90 degrees, and metal cylinders 13 and 15 are arranged on both sides of the piezoelectric ceramics 11 and 12, as shown in FIG. 4 (b). These two piezoelectric ceramic discs and three metal cylinders are joined together. The joining method is performed by using an adhesive such as an epoxy resin or by soldering. FIG. 5 is a perspective view showing another structural example of the piezoelectric elliptical motion oscillator according to the second embodiment of the present invention. In FIG. 5, a disk-shaped piezoelectric vibrator
16 is a piezoelectric ceramic disc similar to that shown in FIG.
16a and 16b are arranged so that their polarization boundary surfaces are aligned with each other, and the polarization directions thereof are opposed to each other.
The two 17b are arranged so that their polarization boundary surfaces are aligned with each other so that their polarization directions face each other. The two disk-shaped piezoelectric vibrators 16 and 17 are sandwiched between the three metal cylinders 13, 14 and 15 and integrally bonded as in the case of FIG.

FIG. 6 is an explanatory diagram of the operation principle of the piezoelectric elliptical motion oscillator according to the second embodiment of the present invention. As shown in FIG. 6 (b), when a voltage is applied to the piezoelectric ceramic disk of (a), elongation strain occurs in the upper half of FIG. 6 (b) (a) and contraction strain occurs in the lower half. Occurs. Therefore, lead terminals 19 and 20
If an AC voltage equal to the resonance frequency is applied between them, a bending resonance in the direction of arrow 6 is generated as shown in FIG. 6 (a).

Similarly, when a similar AC voltage is applied to the piezoelectric ceramic disk of FIG. 6 (b) (b), the direction of the polarization boundary line is perpendicular to that of the case of FIG. 6 (b) (a). A bending resonance occurs in a direction perpendicular to the vibration direction of FIG. Therefore, by shifting the phase of the drive voltage applied to the lead terminals 19-20 and 21-20 by 90 °, the circular vibration as shown by the arrow in FIG. Elliptical vibration can be excited.

Although the above explanation has been given for the piezoelectric elliptic motion oscillator shown in FIG. 4, in the piezoelectric elliptic motion oscillator shown in FIG. 5, the drive electric terminal is taken out from the joint portion of the two piezoelectric ceramic disks. This makes it possible to drive two piezoelectric ceramics piezoelectric elliptical motion disks in parallel.
Driving at a lower voltage than that shown in the figure is possible.

Third Embodiment FIG. 7 is a perspective view showing an example of the structure of a piezoelectric elliptical motion oscillator according to a third embodiment of the invention. In FIG. 7, each of the cylindrical piezoelectric vibrators 31 and 31 ′ has a polarization boundary surface that is divided into two in the direction along the center, and the polarization directions of two substantially symmetrical regions on both sides of this polarization boundary surface are thick. Piezoelectric ceramics that are polarized so that they are polarized in opposite directions to each other in the vertical direction Is configured. In the third embodiment, two of the above-mentioned cylindrical piezoelectric vibrators are arranged so as to sandwich the metal cylinder 35 so that their polarization boundary surfaces show directions at right angles to each other. Metal cylinders 36 and 37 are arranged on the outside, respectively, and they are integrally tightened by a central bolt 38 and nuts 39 and 39 'as shown in FIG. 7 (b).

In the third embodiment, as shown in FIG. 7, the two piezoelectric vibrator pairs and the metal cylinders 35, 36 and 37 are connected to the center bolt 38 and the nuts 39 and 3, respectively.
9'is integrally tightened, but the same effect can be obtained by directly threading the metal cylinders 36, 37 and using them as nuts.

FIG. 8 is an explanatory diagram of the operating principle of the piezoelectric elliptical motion oscillator of the present invention. In FIG. 8 (b) (a), when the intermediate terminal plate of the cylindrical piezoelectric vibrator 31 is used as a common ground and a positive voltage is applied to both end surfaces, expansion strain occurs in the upper half of the cylindrical piezoelectric vibrator, Shrinkage distortion occurs in the lower half. Therefore,
When an AC voltage having a frequency equal to the resonance frequency of the piezoelectric vibrator is applied between the lead terminals 41 and 42, bending resonance in the direction of the arrow is generated as shown in FIG. 8 (a).

Similarly, when a similar AC voltage is applied to the cylindrical piezoelectric vibrator of FIG. 8 (b) and (b), bending resonance occurs in the direction perpendicular to the direction of the arrow in FIG. 8 (a). Therefore, lead terminals 41-42
By shifting the phase of the drive voltage applied to the lead terminals 43-42 by 90 °, the piezoelectric elliptical motion oscillator 40 is provided with an eighth
Circular vibration or elliptical vibration as shown in FIG. 7C can be excited.

(Effects of the Invention) As described above, in the piezoelectric elliptical motion oscillator of the present invention, since the piezoelectric oscillator has a simple shape, and in particular, has a circular cross section, high-precision machining is possible. It is possible to obtain a vibrator with little variation in resonance frequency in the directions orthogonal to each other. In addition, the circular cross section makes it possible to obtain a stable motor with a good contact state with the cup-shaped rotating roller when the ultrasonic motor as shown in FIG. 10 is constructed. Further, in the piezoelectric elliptic motion oscillator of the present invention, since no adhesive is used, there is little variation in characteristics due to adhesion, and the effect is practically large.

Further, in another piezoelectric elliptical motion oscillator of the present invention, since each member is tightened with bolts and nuts, it is highly reliable without risk of peeling even if high power is input and driven. A vibrator is obtained. Also, in terms of dimensions, it is determined in relation to the required power, but the diameter is 5 mm
It is possible to easily manufacture oscillators of a certain size and realize a small ultrasonic motor.

[Brief description of drawings]

FIG. 1 is a perspective view of a piezoelectric elliptical motion oscillator according to a first embodiment of the present invention, and FIGS. 2A and 2B are provided for explaining a strain generation state of the piezoelectric elliptical motion oscillator of FIG. Sectional view, third
FIGS. 4A and 4B are diagrams showing vibration of the piezoelectric elliptical motion oscillator shown in FIG. 1, and FIGS. 4A and 4B are piezoelectric elliptical motion oscillators according to a second embodiment of the present invention and the same. FIG. 5A and FIG. 5B are perspective views showing assembly, FIG. 5A and FIG. 5B are perspective views showing another piezoelectric elliptical motion oscillator and its assembly according to the second embodiment of the present invention.
Fig. 6 (a), (b) (a), (b) (b) and (c)
Is a perspective view showing the operating principle of the piezoelectric elliptical motion oscillator according to the second embodiment of the present invention, and FIGS. 7A and 7B show a piezoelectric elliptical motion oscillator according to the third embodiment of the present invention and its assembly. 8A, 8B, and 8C are perspective views showing the operating principle of the piezoelectric elliptical motion oscillator according to the third embodiment of the present invention, and FIG. 9 is a piezoelectric ellipse according to the conventional example. FIG. 10 is a perspective view showing the operation principle of the motion oscillator, and FIG. 10 is a perspective view showing the configuration of a piezoelectric elliptical motion oscillator according to a conventional example. In the figure, 1 is a ceramic cylinder, 2, 3, 4 and 5 are electrodes, 11
And 12 are ceramic discs, 13, 14 and 15 are metal cylinders, 1
6 and 17 are piezoelectric vibrators, 16a, 16b, 17a and 17b are piezoelectric ceramic disks, 18 is a piezoelectric elliptical motion vibrator, 19, 20 and 21 are lead terminals, 31 and 31 'are piezoelectric vibrators, 32 and 33 is a piezoelectric ceramic disk, 34 is a disk-shaped metal terminal, 35, 36 and 37 are metal cylinders, 38 is a bolt, 39, 39 'is a nut, 40 is a piezoelectric elliptical motion oscillator, 41, 42 and 43 are leads. Terminal, 100 is a prismatic vibrator, 120 is a metal prism, 121a and 121b are piezoelectric ceramic thin plates, 122a and 122b are lead terminals, 123 is a ground terminal, 124a and 124b are discs, 125a and 125b are support pins, 126a and 126b. Is a cup-shaped rotating roller.

Continuation of the front page (56) Reference JP 63-240380 (JP, A) JP 63-224681 (JP, A) JP 61-55012 (JP, A) JP 63-11075 (JP , A) JP 63-220781 (JP, A) US Patent 2439499 (US, A) Proceedings of the Acoustical Society of Japan, March 1987, p. 673-674 “Electrical and mechanical oscillators and their applications”, Corona Publishing Co., Ltd., March 30, 1974, p. 271,

Claims (4)

[Claims] 1. A plurality of electrode pairs are provided on an outer peripheral surface of a piezoelectric ceramics column at predetermined intervals in parallel with a length direction,
A DC voltage is applied to at least one of the electrode pairs to subject the piezoelectric ceramic cylinder to polarization treatment in a direction perpendicular to the length direction, and AC voltages having different phases are applied to two of the electrode pairs. Then, a piezoelectric elliptic motion oscillator capable of exciting an elliptic motion including a circle at both ends of the piezoelectric ceramic cylinder. 2. A first and a second piezoelectric ceramic disk, a first metal cylinder sandwiched between one ends of the first and the second piezoelectric ceramic disk, and a first and a second piezoelectric material. A piezoelectric elliptical motion oscillator having second and third metal cylinders respectively provided on the other end of the ceramic disc, wherein the first piezoelectric ceramic disc is the same as the first piezoelectric ceramic disc. The second piezoelectric ceramic discs are polarized so as to be opposite to each other in the thickness direction with a first boundary surface that is divided in two in the direction along the central axis as a boundary. It is divided in two in the direction along the central axis and is polarized so as to be opposite to each other in the thickness direction with a second boundary surface inclined at a predetermined angle from the first boundary surface as a boundary. The metal of the above is used as a common earth, and the phases different from each other are applied to the second and third metal cylinders. An AC voltage is applied to the piezoelectric elliptical motion oscillator, characterized in that the excitable an elliptical motion comprising a circle at both ends of the piezoelectric elliptical motion oscillator. 3. A first and a second disk-shaped piezoelectric vibrators, and a first sandwiched between one ends of the first and the second disk-shaped piezoelectric vibrators.
A piezoelectric elliptical motion oscillator having: a metal cylinder; and a second and a third metal cylinder provided at the other ends of the first and second disk-shaped piezoelectric vibrators, respectively. The disk-shaped piezoelectric vibrator has a thickness that is divided by a first boundary surface that divides the first disk-shaped piezoelectric vibrator in a direction along the central axis and a second boundary surface that divides the first disk-shaped piezoelectric vibrator in the thickness direction. The second disk-shaped piezoelectric vibrators are polarized in opposite directions to each other in the vertical direction, and the second disk-shaped piezoelectric vibrators are arranged in a direction along the central axis of the second disk-shaped piezoelectric vibrators.
Polarization is performed so as to be opposite to each other in the thickness direction with a third boundary surface that is divided and inclined at a predetermined angle with the first boundary surface and a fourth boundary surface that is divided into two in the thickness direction as boundaries. The first, second, and third metal cylinders are used as a common ground, and alternating voltages having mutually different phases are applied to the second and fourth boundary surfaces to generate the piezoelectric elliptical motion oscillator. A piezoelectric elliptical motion oscillator characterized in that it is possible to excite an elliptical motion including a circle at both ends. 4. A first and a second cylindrical piezoelectric vibrators, and a first sandwiched between one ends of the first and the second cylindrical piezoelectric vibrators.
A piezoelectric elliptic motion oscillator in which a metal cylinder and a second and a third metal cylinder provided at the other ends of the first and second cylindrical piezoelectric vibrators are fixed by a penetrating member, respectively. The first cylindrical piezoelectric vibrator has a first boundary surface divided into two in a direction along a central axis of the first cylindrical piezoelectric vibrator and a second boundary surface divided into two in a thickness direction as boundaries. Polarized so as to be opposite to each other in the thickness direction, the second cylindrical piezoelectric vibrator is divided into two in a direction along the central axis of the second cylindrical piezoelectric vibrator, and the first cylindrical piezoelectric vibrator is divided into two. The third boundary surface inclined at a predetermined angle with the second boundary surface and the fourth divided into two in the thickness direction.
Are polarized so as to be opposite to each other in the thickness direction with the boundary surface of the first boundary surface as a boundary, and the first and second intermediate terminal plates are provided on the second and fourth boundary surfaces, respectively. , Second and third
A piezoelectric body characterized in that the metal cylinder is used as a common ground, and alternating voltages having different phases are applied to the intermediate terminal plate to excite elliptical motion including circles at both ends of the piezoelectric elliptical motion oscillator. Elliptical motion oscillator.