JPH072228B2 - Piezoelectric elliptical motion oscillator - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a small motor used in electronic equipment, and more particularly to a piezoelectric elliptical motion oscillator used in 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. 5 is a schematic view showing the structure of a conventional piezoelectric elliptical motion oscillator, that is, a prismatic oscillator 100 used in a small ultrasonic motor. The structure is shown on two adjacent surfaces of a metal prism 120 having a substantially square cross section. Electrodes are formed and piezoelectric ceramic thin plates 121a and 121b polarized in the thickness direction are bonded. From the surface electrodes of the piezoelectric ceramic thin plates 121a and 121b to the lead terminals 122
a122b is pulled out, and the common ground terminal 12
3 is pulled out. 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, the lead terminal 122a
When an alternating voltage whose frequency is equal to the resonance frequency and whose phase is different by 90 ° is applied to −123 and 122b1-123, both ends of the metal prism 120 vibrate rotationally or elliptically.

FIG. 6 is a diagram showing a configuration example of an ultrasonic motor using the prismatic vibrator 100 shown in FIG. 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. Discs 124a, 12 provided at both ends of the prismatic vibrator 100
4b is inserted into the cavity of the cup-shaped rotary rollers 126a and 126b rotatably supported by the rotation shaft, and 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. 5, since the oscillator is a prism having a square cross section, the resonance frequencies of the bending motors in the directions orthogonal to each other are The processing accuracy of the prisms must be strictly controlled in order to match them with good accuracy. Further, when the piezoelectric ceramic thin plate is bonded to the metal prism, the bonding state varies widely.

A technical object of the present invention is to provide a piezoelectric elliptical motion oscillator which is not limited in processing accuracy, has a simple shape, is easy to assemble, and can be stably driven with less variation due to adhesion.

[Means for Solving the Problem] According to the present invention, a pair of end plates having four side surfaces of a prism having a square cross section as pedestals are arranged so as to face each other at a predetermined interval, and the pair of end plates is provided. A piezoelectric elliptical motion oscillator is obtained in which four rectangular plate-shaped piezoelectric oscillators having the same shape and the same size are joined to their corresponding pedestals.

According to the present invention, a pair of end plates having four side surfaces of a square prism as a pedestal are arranged to face each other with a predetermined gap,
A rod or a pipe having a cross-sectional size smaller than the cross-section of the end plate is arranged between the facing surfaces of the pair of end plates with the center axes of the end plates aligned with each other, and the rods or pipes are mounted on the corresponding pedestals of the pair of end plates. A piezoelectric elliptical motion oscillator is obtained by joining four rectangular plate-shaped piezoelectric oscillators having the same shape and the same size.

[Operation] The operation of the present invention will be described.

In the piezoelectric elliptical motion oscillator of the present invention, four rectangular plate-shaped piezoelectric vibrators are provided so as to form the four side surfaces of the prism, and the polarization direction is changed from the inside to the outside, and a pair of opposing elliptical motion oscillator plates are provided. By applying drive voltages having different phases (preferably 90 °) to the both ends, the both ends of the piezoelectric vibrator perform elliptical vibration including a circle.

Embodiments Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view showing a structural example of a piezoelectric elliptical motion oscillator according to an embodiment of the present invention. In this figure, the rectangular plate-shaped piezoelectric ceramic plate 1 has electrodes formed on both sides and is polarized in the thickness direction. The end plates 2 and 2'have fixed pedestals 2a, 2a 'having a square cross section. In the embodiment, an end plate 2 in which four rectangular piezoelectric ceramic plates having the same size and shape are arranged at a predetermined interval as shown in FIG.
And 2'of the fixed pedestals 2a and 2a 'are bonded symmetrically.

FIG. 2 is a perspective view showing an example of a support for forming a piezoelectric elliptical motion oscillator having another structure of the present invention. In FIG. 2, end plates 5 and 5'having a square cross section are provided at both ends of rods or pipes 3 and 3'which are smaller than the size of the end plates 5 and 5 '. Friction members 4 and 4'are provided at both ends thereof.

FIG. 3 shows a fixed pedestal 2a provided on the support base shown in FIG.
FIG. 3 is a perspective view of a piezoelectric elliptical motion oscillator configured by adhering a rectangular piezoelectric ceramic plate so as to straddle 2a ′ and 2a ′.

FIG. 4 is a diagram for explaining the operation principle of the piezoelectric elliptical motion oscillator according to the embodiment of the present invention.

In FIG. 4 (a), the polarization strips of the piezoelectric ceramic plates 11 and 13 are oriented from the inside to the outside. In this state, if the lead terminals 16 and 18 are connected to form a negative terminal and the lead terminals 15 and 17 are connected to form a positive terminal, the polarization direction and the electric field direction are opposite in the piezoelectric ceramic board 11. Because of this, shrinkage distortion in the thickness direction occurs,
As a result, elongation strain occurs in the length direction.

On the other hand, in the piezoelectric ceramic plate 13, since the polarization direction and the electric field direction are the same, extension strain occurs in the thickness direction,
As a result, shrinkage distortion occurs in the length direction.

Based on this principle, the piezoelectric elliptical motion oscillator according to the embodiment,
Bending resonance occurs in the direction perpendicular to the direction of arrow 19 shown in FIG. Therefore, the piezoelectric ceramic plates 11, 13 and 12,
By shifting the phase of the driving voltage applied to each of the coils 14 by 90 °, a circular vibration or an elliptical vibration as shown in FIG. 4B can be excited at both ends of the piezoelectric elliptical motion oscillator 10.

[Effects of the Invention] As described above, in the piezoelectric elliptical motion oscillator of the present invention, since each member constituting the piezoelectric oscillator has a simple shape, high-precision machining is possible, and it is possible to make a right angle It is possible to obtain a vibrator with a small variation in resonance frequency in different directions.

Further, in the piezoelectric elliptical motion oscillator of the present invention, since the rectangular plate is used as the piezoelectric oscillator, the impedance is low and it is possible to drive at a low voltage.

Further, in the piezoelectric elliptic motion oscillator of the present invention, since the piezoelectric ceramic plate and the pedestal are bonded at both ends where almost no strain is generated, a vibrator with less variation in vibration due to bonding can be obtained. Although the size is determined by the required power, a transducer having a side width of about 5 mm can be easily manufactured, and a small ultrasonic motor can be realized.

[Brief description of drawings]

1 (a), (b), (c), and (d) are perspective views showing the assembly of a piezoelectric elliptical motion oscillator according to an embodiment of the present invention, and FIGS. 2 (a) and (b) are FIG. 4 is a perspective view showing a support base of a piezoelectric elliptical motion oscillator according to another embodiment of the present invention, FIG. 3 is a perspective view showing a configuration of a piezoelectric elliptical motion oscillator according to another embodiment of the present invention, and FIG. (A) And (b) is a figure which shows the operating principle of the piezoelectric elliptical motion oscillator which concerns on the Example of this invention, FIG. 5 is a perspective view which shows the operating principle of the piezoelectric elliptical motion oscillator which concerns on a prior art example, 6th. FIG. 1 is a perspective view showing a configuration of a piezoelectric elliptical motion oscillator according to a conventional example. In the figure, 1, 1a, 1b, 1c and 1d are piezoelectric ceramic plates and 2, 2'5
5'is an end plate, 3 is a square bar, 4, 4'is a friction member, 15, 16 and 1
7 and 18 are terminals, 19 and 20 are arrows indicating the direction of movement, 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, and 124a and 124b. Are discs, 125a and 125b are support pins, and 126a and 126b are cup-shaped rotating rollers.

Continuation of the front page (56) References JP-A-62-106314 (JP, A) Actual development: S59-137568 (JP, U) West German patent publication 1488698 (DE, A)

Claims (2)

[Claims] 1. A pair of end plates having four side surfaces of a prism having a square cross section as pedestals are arranged so as to face each other at a predetermined interval.
A piezoelectric elliptical motion oscillator, characterized in that four rectangular plate-shaped piezoelectric oscillators having the same shape and the same size are joined to corresponding pedestals of the pair of end plates. 2. A pair of end plates having four side faces of a square prism having a square cross section as pedestals are arranged so as to face each other at a predetermined interval.
Bars or pipes having a cross-sectional dimension smaller than the cross section of the end plates are arranged between the facing surfaces of the pair of end plates with the center axes of the end plates aligned with each other, and the respective pedestals of the pair of end plates corresponding to each other. A piezoelectric elliptical motion oscillator characterized in that four rectangular plate-shaped piezoelectric oscillators having the same shape and the same size are joined to each other.