JPH0236772A - Piezoelectric elliptical motion vibrator - Google Patents

Abstract

PURPOSE:To easily assembly by so providing 4 rectangular platelike piezoelectric vibrators as to form four side faces of a square column, and applying a driving voltage thereto with a polarizing direction from inside to outside. CONSTITUTION:Electrodes are formed on both side faces of a rectangular platelike piezoelectric ceramic plate 1, and polarized in its thicknesswise direction. End plates 2, 2' have stationary pedestals 2a, 2a, having a square-shaped sectional shape. The four ceramic plates having the same size and shape adhere symmetrically to the pedestals 2a, 2a' of the plates 2, 2' disposed at a predetermined interval. Thus, driving voltages having 90 deg. of different phases are applied to a pair of opposed plates 1 to move the both ends in an elliptical vibration including a circle.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a small motor used in electronic equipment, and more particularly to a piezoelectric elliptic motion vibrator used in a small ultrasonic motor with a small rotor diameter.

[Conventional technology] In general, ultrasonic motors have the following advantages compared to conventional electromagnetic motors:
It has the advantages of being able to obtain high torque at low rotation speeds, having stopping power, and having little electromagnetic noise, and is used for autofocus of cameras and power motors for automobiles.

FIG. 5 is a schematic diagram showing the structure of a conventional piezoelectric elliptical motion vibrator, that is, a prism vibrator 100 used in a small ultrasonic motor. Electrodes are formed and piezoelectric ceramic thin plates 121a and 121b polarized in the thickness direction are bonded. Lead terminals 122a122b are drawn out from the surface electrodes of the piezoelectric ceramic thin plates 121a and 121b, and a common ground terminal 123 is drawn out from the metal prism 120. Since the cross-sectional shape of the metal prisms 120 is approximately square, the metal prisms 120 bend and vibrate in directions perpendicular to each other at approximately the same resonance frequency. Therefore, lead terminal 122a-12
3 and 122b-123, when alternating current voltages having a frequency equal to the resonance frequency and having a phase different by 90 degrees are applied, both ends of the metal prism 120 undergo rotational vibration or elliptical vibration.

FIG. 6 is a diagram showing an example of the configuration of an ultrasonic motor using the prismatic vibrator 100 shown in FIG. 5. Discs 124a, 124b are attached to both ends of the prismatic vibrator 100, and support pins 125a,
125b is formed, and the prismatic vibrator 100 is connected to the support pin 12.
It is stably supported by 5a and 125b. Disc plates 124a and 124b provided at both ends of the prismatic vibrator 100
are inserted into the cavities of cup-shaped rotary rollers 126a and 126b rotatably supported by a rotating shaft, and are pressed into contact with the inner walls of the cavities.

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

[A section that tries to invent or solve! ! i] However, in the conventional prismatic elliptical motion oscillator as shown in Fig. 5, the oscillator is a prismatic pillar with a square cross section. The machining accuracy must be strictly controlled. Furthermore, there are large variations in the bonding state when bonding the piezoelectric ceramic thin plate to the metal prism.

The technical problem of the present invention is to provide a piezoelectric elliptic motion vibrator that is not concerned with processing accuracy, has a simple shape, is easy to assemble, and can be driven stably with little variation due to adhesion.

[Means for Solving the Problem] According to the present invention, a pair of end plates each having four side surfaces of a prism with a square cross section as pedestals are arranged facing each other at a predetermined interval, and the pair of end plates A piezoelectric elliptic motion vibrator characterized in that four rectangular plate-shaped piezoelectric vibrators of the same shape and size are bonded to the corresponding pedestal of the plate is obtained.

According to the present invention, a pair of end plates each having four side surfaces of a square prism as pedestals are arranged facing each other at a predetermined interval,
A rod or pipe having a cross-sectional dimension smaller than the cross-section of the end plate is arranged between the opposing surfaces of the pair of end plates so that the end plate and the central axis coincide with each other, and the rod or pipe is placed on the corresponding pedestal of the pair of end plates. A piezoelectric elliptic motion vibrator is obtained, which is characterized in that it is formed by joining four rectangular plate-shaped piezoelectric vibrators of the same shape and size.

For quantification] The operation of the present invention will be explained.

In the piezoelectric elliptical motion vibrator of the present invention, four rectangular plate-shaped piezoelectric vibrators are provided so as to form four sides of a prism, and the direction of the hot water is from the inside to the outside, and the elliptic motion vibrator plates facing each other are provided. By applying driving voltages having different phases (preferably 90 degrees) to the pair, both ends of the piezoelectric vibrator perform elliptical vibration including a circle.

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

FIG. 1 is a perspective view showing an example of a top-mounted piezoelectric elliptic motion vibrator according to an embodiment of the present invention. In this figure, a rectangular 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 and 2a- each having a square cross-sectional shape. In the example, four rectangular piezoelectric ceramic plates with the same dimensions and shape were used.
As shown in FIG. 1, the book is constructed by adhering symmetrically to fixed pedestals 2a and 2a- of end plates 2 and 2- arranged at a predetermined interval.

FIG. 2 is a perspective view showing an example of a support base constituting a piezoelectric elliptic motion vibrator having another structure according to the present invention. In FIG. 2, end plates 5 and 5- of square cross-section are used for supporting or vibrating devices 3 and 3- whose dimensions are smaller than those of the end plates 5 and 5-.
provided at both ends of the Friction members 4 and Xl- are provided at both ends.

Figure 3 shows the fixed position pi installed on the support stand shown in Figure 2.
FIG. 2 is a perspective view of a piezoelectric elliptic motion vibrator constructed by bonding rectangular piezoelectric ceramic plates so as to span 2a and 2a-.

FIG. 4 is a diagram for explaining the operating principle of the piezoelectric elliptic motion vibrator according to the embodiment of the present invention.

In FIG. 4(a), piezoelectric ceramic plates 11 and 1
The direction of polarization in 3 is from the inside to the outside. In this state, connect the lead terminals 16 and 18,
If a negative terminal is used, and lead terminals 15 and 17 are connected to form a positive terminal, in the piezoelectric ceramic plate 11, the direction of polarization and the direction of the electric field will cause shrinkage distortion in the direction of the thickness, with the direction of polarization being opposite. Elongation strain occurs in the horizontal direction.

On the other hand, in the piezoelectric ceramic plate 13, since the direction of polarization and the direction of the electric field are the same, an elongation strain occurs in the thickness direction, and as a result, a shrinkage strain occurs in the length direction.

Based on this principle, the piezoelectric elliptic motion vibrator according to the embodiment
Bending resonance occurs in the direction perpendicular to the direction of the arrow 19 shown in FIG.
and 12. The phase of the drive voltage applied to 14 is 90'.
By shifting the piezoelectric elliptic motion oscillator 10 by ``, circular vibration or elliptical vibration as shown in FIG. 2(c) can be excited at both ends of the piezoelectric elliptic motion vibrator 10.

[Effects of the Invention] As explained above, in the piezoelectric elliptical motion vibrator of the present invention, since the shapes of each member constituting the piezoelectric vibrator are simple, high-precision processing is possible and A vibrator with less variation in resonance frequency and number in different directions can be obtained.

Further, in the piezoelectric elliptic motion vibrator of the present invention, since a rectangular plate is used as the piezoelectric vibrator, the impedance is low, and driving at a low voltage is possible.

Furthermore, in the piezoelectric elliptic motion vibrator of the present invention, since the piezoelectric ceramic plate and the pedestal are bonded at both ends where almost no distortion occurs, a vibrator with less variation in vibration due to bonding can be obtained. Further, although the dimensions are determined by the required power, a vibrator with a width of about 5 mm on the negative side can be easily manufactured, and a small ultrasonic motor can be realized.

[Brief explanation of the drawing]

FIGS. 1(a), (b), (c), and (d) are perspective views showing the assembly of a piezoelectric elliptic motion vibrator according to an embodiment of the present invention, and FIGS. 2(a) and (b) are FIG. 3 is a perspective view showing a support base of a piezoelectric elliptic motion vibrator according to another embodiment of the present invention; FIG. 5 is a perspective view showing the operating principle of a piezoelectric elliptic motion vibrator according to an embodiment of the present invention, FIG. 5 is a perspective view showing the operating principle of a piezoelectric elliptic motion vibrator according to a conventional example, and FIG. It is a perspective view showing the configuration of an elliptical motion vibrator. In the figure, 1. la, lb, lc, and 1 d are piezoelectric ceramic plates, 2. 2-5 and 5- are end plates, 3 is a square piece, and 4 and 4 degrees are piezoelectric ceramic plates. Friction members, 15, 16, 17 and 18 are terminals, 19 and 20 are arrows indicating the direction of movement, 100 is a prismatic gA mover, 1
20 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 disks, 125a
and 125b are support pins, and 126a and 126b are cup-shaped rotating rollers. Figure 2

Claims (2)

[Claims] 1. A pair of end plates each having four side surfaces of a prism with a square cross section as pedestals are arranged facing each other at a predetermined interval, and a plate of the same shape and size is placed on each corresponding pedestal of the pair of end plates. A piezoelectric elliptic motion vibrator characterized by being formed by joining four rectangular plate-shaped piezoelectric vibrators. 2. A pair of end plates each having four sides of a prism with a square cross section as pedestals are arranged facing each other at a predetermined interval, and a cross-sectional dimension between the opposing surfaces of the pair of end plates is smaller than the cross-section of the end plate. A bar or a pipe is arranged so that the end plate and the central axis are aligned, and on each corresponding pedestal of the pair of end plates,
A piezoelectric elliptic motion vibrator characterized by being formed by joining four rectangular plate-shaped piezoelectric vibrators of the same shape and size.