JPH04133678A - Ultrasonic motor - Google Patents

Abstract

PURPOSE:To obtain a rod-shaped ultrasonic motor capable of fixing any portion of the main body of a vibrating element without giving any special vibration isolator and without disturbing the vibration of the vibrating element, by fixing a contacting element connected by pressure welding to the vibrating element at the predetermined position and by rotating the vibrating element. CONSTITUTION:If an AC voltage V1 is applied between an electrode plate 12 and an electrode plate 11 and an AC voltage V2 is applied between an electrode plate 12 and an electrode plate 13, then a vibrating element A makes a circular motion similar to a motion created by the turning rope for rope skipping with the center of motion located at the center of shaft of said vibrating element. By utilizing the rope skipping motion at a conical portion 1a of an oscillator 1, the vibrating element A itself is rotated by the frictional force between the conical portion 1a and a supporting portion 2 as a contacting element fixed to a predetermined position. In this case, the supporting portion 2 is in stationary state without rotating and also is isolated from the vibration of the vibrating element A, therefore, the supporting portion 2 is freely fixed without affecting the vibration of the vibrating element A.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention vibrates an elastic body as a rod-shaped vibrating body by supplying electrical energy to an electric-mechanical energy conversion element provided on the rod-shaped elastic body. The present invention relates to an ultrasonic motor that generates circular or elliptical motion in the mass point of a vibrator and frictionally drives a moving body pressed against the vibrator, and is particularly suitable for optical equipment such as cameras and office equipment such as printers. .

[Prior art] Conventional ultrasonic motors have been of the type that causes bending vibrations in an annular elastic body and uses frictional force to drive a moving body for driving a lens, but these motors have not been put to practical use in AF mechanisms for cameras, etc. There is. However, since this conventional type is ring-shaped, it cannot be used as a unit including a pressurizing mechanism.
The cost is relatively high, and it is disadvantageous in terms of cost for motor applications that do not require a hollow space. Therefore, with a solid type,
A type of motor that is easy to configure, such as a pressurizing system, was recently proposed by the present applicant in Japanese Patent Application No. 1-173528.

Figures 5 (a) and (b) show the ultrasonic motor according to the proposal. Body A
Three bolts 14 having spherical tips are pressed against the outer peripheral surface of the bolt 14, and each of the bolts 14 is screwed into a fixed cylinder 15.

Note that the rotor (not shown) has a cylindrical shape, and its tip touches the conical portion 1a of the vibrating body A, so that the conical portion 1a
receives more driving force.

[Problems to be Solved by the Invention] As described above, the proposed motor has a structure in which one end of the vibrating body is supported at a predetermined position, which adversely affects the vibration characteristics of the vibrating body.

[Means for Solving the Problem] In order to solve the problem, the present invention generates vibrations in a plurality of different planes of the vibrating body by applying an electric signal to an electric-mechanical energy conversion element provided in the vibrating body. and causing a rotational movement on the surface of the vibrating body by exciting each vibration and giving a predetermined phase difference in time to each vibration,
In an ultrasonic motor that frictionally drives a contact body press-fitted with the vibrating body, the contact body is fixed at a predetermined position and the vibrating body is rotated.

[Embodiment] FIG. 1 is a sectional view of a first embodiment of an ultrasonic motor according to the present invention. 1 is a metal vibrator having a conical part 1a, an output extraction shaft 1e, a small diameter part 1b, a large diameter part 1c, and a conical part 1d having the same diameter as the small diameter part 1b, and the conical part 1a is in frictional contact with the support 2; 3.7 is an annular piezoelectric element having the same diameter as the rear end of the vibrator 1, and 11 and 12.13 are electrode plates of the piezoelectric element 3.7, which are slid onto the annular electrode bodies 4 and 5.6, respectively. There is a moving contact. Reference numeral 8 denotes a cylindrical holding member whose rear end is pressed by a disk spring 9. A piezoelectric element 3.7 is arranged between the vibrator 1 and the holding member 8, with the electrode plates II and 12.13 alternately sandwiched between them as shown in the second diagram, and the holding member 8 and the piezoelectric element are connected by adhesive, bolts, etc. 3, 7 and vibrator 1
A vibrating body A consisting of 1.3 and 7.8 is constructed by fixing each of them.

Here, the operating principle of the ultrasonic motor shown in FIGS. 1 to 3 will be explained. As shown in FIG. 2, the piezoelectric element 3°7 is
Two electrodes (+electrode a, -electrode b) having different polarization directions on one side and polarized in the thickness direction are formed symmetrically on both sides of an insulating part d formed at the central axis position, and the other A common electrode C consisting of ten electrodes a and - electrodes is formed on the surface side, and they are arranged so that their positional phases are shifted from each other by an angle of 906 with respect to the axis of the vibrating body A.

Then, an AC voltage vl is applied between the electrode plate 12 and the electrode plate 11.
, and an AC voltage V2 is applied between the electrode plate 12 and the electrode plate 13.
By applying , the vibrating body A is caused to vibrate by combining the vibration due to the expansion/contraction displacement of the piezoelectric element 3 in the thickness direction and the vibration due to the expansion/contraction displacement of the piezoelectric element 7 in the thickness direction.

As shown in FIG. 3, the AC voltage (1) and the AC voltage V2 have the same amplitude and frequency, but have a temporal and spatial phase shift of 90°.

Therefore, when the alternating current voltages V, , V2 are applied, the vibrating body A performs a circular motion (hereinafter referred to as "jumping rope vibration") like a bending and stretching rope around the axis. Note that the principle by which the 29-circular motion occurs is well known, so the explanation thereof will be omitted. This embodiment utilizes the rope-jumping motion of the conical portion 1a of the vibrator 1, and uses the frictional force in the conical portion 1a between it and the support 2, which is a contact body fixed at a predetermined position, to The vibrating body A itself rotates. Here, the support body 2 is in a stationary state without rotating and is insulated from the vibration of the vibrating body A, so unlike the conventional example, the support body 2 is supported without affecting the vibration of the vibrating body A. You can freely fix your body.

Further, since the disc spring 9 is used to press the vibrating body A and the support body 2 together, and the pressure is applied at the axial center of the vibrating body A, inhibition of rotation due to friction, that is, a decrease in efficiency can be prevented.

In addition, when pressing the vibrating body A and the supporting body 2, it is also possible to magnetize their contact surfaces to north and south poles and use magnetic force. In this case, the influence of the pressure mechanism on the vibration of the vibrating body A is even smaller, and the force that impedes rotation becomes zero.

[Other Embodiments] FIG. 4 shows another embodiment of the ultrasonic motor of the present invention, in which I is a vibrator made of a metal round bar, and a support member 2A is connected to the conical portion 1a.
The friction diameter is the same. Support 2 fixed in place
A has a notch 2AA into which a gear (not shown) for output output is loosely fitted. Reference numeral 8 denotes a pressing member whose rear end is pressurized by a disc spring 9, and the vibrator 1, the piezoelectric elements 3 and 7, and the pressing member 8 constitute a vibrating body A. Reference numeral 20 denotes an output extraction gear provided at the node signal of radial vibration in order to reduce the influence on the vibration of the vibrating body A. The gear 20 is engaged with the aforementioned gear (not shown), and the gear 20 is engaged with the aforementioned gear (not shown). A
By rotating, force can be transmitted to the outside.

If the gear is provided at a position other than the vibration node, the radial vibration will cause it to collide with the aforementioned mating gear (not shown), resulting in unstable vibration or generation of noise. - At a node position such as in the strength tree embodiment, the vibration displacement occurs only in the axial direction, so slippage only occurs at the gear contact portion. Furthermore, even when using a belt instead of the aforementioned gear as an output extraction method, if the belt is installed at the node of radial vibration, instability of vibration resulting from changes in belt tension due to radial vibration can be reduced. It can be removed.

In the case of this embodiment, as in the first embodiment, the support body 2 can be freely fixed without disturbing the vibration of the vibrating body A.

[Effects of the Invention] As explained above, according to the present invention, by rotating the vibrating body itself, any part of the vibrating body body can be fixed (fixed and It is possible to provide a rod-shaped ultrasonic motor that does not inhibit the vibration of the vibrating body.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an ultrasonic motor according to a first embodiment of the present invention, FIG. 2 is a perspective view showing the shape of a piezoelectric element as an electric-mechanical energy conversion element shown in the first diagram, and FIG. 1 is a waveform diagram of an AC voltage applied to a piezoelectric element; FIG. 4 is a sectional view of another embodiment of the present invention; FIG. 5(a),
(b) is a schematic configuration diagram of a conventional ultrasonic motor. In the figure, 1... Vibrator 2... Support body. Figure 2

Claims (1)

[Claims] Vibration is excited in a plurality of different planes of the vibrating body by applying an electric signal to an electro-mechanical energy conversion element provided on the rod-shaped vibrating body, and each vibration is given a predetermined phase difference in time. In an ultrasonic motor that generates rotational motion on the surface of the vibrating body and frictionally drives a contact body press-fitted with the vibrating body, the contact body is fixed at a predetermined position, and the vibrating body is An ultrasonic motor characterized by rotating.