JPH0491678A - Supersonic motor - Google Patents

Abstract

PURPOSE:To enable the accurate positioning of piezoelectric elements by providing the piezoelectric elements, which abut on a power supply member, with positioning means, which regulate the positions inside the planes perpendicular to the axial direction of an elastic body. CONSTITUTION:For piezoelectric element plates 30 and 40, which are stacked with a power supply member (electrode plate) 50 between, electrodes a and b are made on both sides of the diameter part on each surface side, and small diameters of through holes 31 and 41 in pairs are formed, for example, axisymmetrically in the insulating parts d at the diameter parts, which are recessed by the amounts of thicknesses of the electrodes a and b. Moreover, each through hole of the piezoelectric element plates 30 and 40 engages with the projections 51 and 52 of the electrode plate 50, and the piezoelectric element plates 30 and 40 on both sides of the electrode plate 50 are laminated, being positioned to have the positional phases of 90 deg. around the axis. Hereby, the piezoelectric element plates 30 and 40 can be positioned in the specified positions.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention vibrates a rod-shaped vibrator by supplying electrical energy to an electro-mechanical energy conversion element provided on a rod-shaped elastic body. This invention relates to an ultrasonic motor that frictionally drives a moving body pressed against a vibrator by causing a mass point to move in a circular or elliptical manner.

[Prior Art] Conventionally, as this type of ultrasonic motor, one shown in FIG. 8, for example, has been proposed.

1 is a horn-shaped horn portion I whose diameter gradually decreases toward the tip between a small-diameter shaft portion 1a at the tip and a large-diameter shaft portion 1b at the rear end.
2 is a vibrating body made of a metal round bar formed with C; 2 is a presser body made of a metal round bar having an outer diameter the same as the large diameter shaft portion 1b of the vibrating body 1; and 3 has a bolt through hole at its axis; and 4 is an annular piezoelectric element plate formed to have the same outer diameter as the large diameter shaft portion 1b; 5 is an electrode plate of the piezoelectric element plate 3.4 between the vibrating body 1 and the presser body 2; , piezoelectric element plate 3 with electrode plate 5 sandwiched therebetween.
．． 4, and by fixing the presser body 2 to the vibrating body 1 with bolts 6, the piezoelectric element plate 3.4 is fixed between the vibrating body 1 and the presser body 2, and the vibrator A is configured. There is. The head of the bolt 6 is in contact with the presser body 2 via the annular insulator 7, and the shaft portion is held in a non-contact state with the piezoelectric element plate 3.4 and the electrode plate 5.

The piezoelectric element plate 3.4 has two electrodes (+ electrode 81a,
The -electrode b) is formed symmetrically on both sides of the insulating part d formed at the central axis position, and the middle electrode a and the common electrode C of the -electrode are formed on the other side. They are arranged with their positional phases shifted by an angle of 90° from each other with respect to the axis. Note that the polarized electrodes (+electrode a, -electrode b) of the piezoelectric element plate 3 are in contact with the rear end surface of the vibrating body 1, which is an electrical conductor, and the piezoelectric element plate 4 is in contact with the front end surface of the presser body 2, which is an electrical conductor. ing.

Then, an AC voltage vI is applied between the 1tti plate 5 and the vibrator 1.
In addition, by applying an AC voltage v2 between the electrode plate 5 and the presser body 2, vibrations due to expansion and contraction displacement in the thickness direction of the piezoelectric element plate 3 and vibrations due to expansion and contraction displacement in the thickness direction of the piezoelectric element plate 4 are reduced. The oscillator A is made to vibrate by the combination of .

As shown in FIG. 9, the AC voltage V and the AC voltage 2 have the same amplitude and frequency, and have a temporal and spatial phase shift of 90°.

Therefore, the vibrator A performs circular motion like a skipping rope (hereinafter referred to as pure vibration) about the axis. Note that the principle behind this circular motion is well known and will not be described here.

As shown in FIG. 10, the rotor 8 is fitted coaxially with the axis l of the vibrator A, and the rear end part (hereinafter referred to as the frictional contact part) sb of the inner diameter part of the rotor 8 corresponds to the sliding part B. Extend it to the position where you want it to be.
The friction contact portion 8b is brought into contact with the sliding portion B of the horn portion IC. The horn portion is provided to obtain an appropriate frictional force in the sliding portion B by receiving pressure in the axial direction.

In the vibrating body 1, this sliding portion B becomes the antinode of the rope-jumping vibration.

The inner diameter of the inner diameter portion 8a of the rotor 8 is a member 8 having a low coefficient of friction.
The rotor 8 has a structure in which it contacts the node of the rope vibration in the vibrating body 1 through the d, and in order to prevent vibrations generated in areas other than the sliding part B from coming into contact and generating sound, the rotor 8 is A relief 8c is provided.

The friction contact portion 8b of the rotor 8 expands into a shape in which the inner diameter gradually increases to match the outer peripheral shape of the sliding portion B, and comes into surface contact with the sliding portion B when the vibrating body 1 performs rope-jumping motion.

The rotor 8 is pushed in the direction of the arrow in FIG. 10 by, for example, a spring (not shown) through a thrust bearing (not shown), and the friction contact part 8b and the sliding part A predetermined frictional force is generated at the contact portion with B, and rotation in the axial direction is permitted by the thrust bearing.

With the above structure, the vibration of the vibrating body 1 becomes a rotational force and is transmitted to the friction contact portion 8b of the rotor, causing the rotor to rotate.

[Problem to be solved by the invention] However, in the above conventional example, ideally the piezoelectric element plate 3
．． The positional phase of 4 must be 90', but there is no means to accurately position it at 901, so it is placed at a deviation from 90°, and when driven by piezoelectric elements 3 and 4, the vibrator The drawback was that it did not move in a clean circular motion, reducing efficiency.

SUMMARY OF THE INVENTION An object of the present invention is to provide an ultrasonic motor that can solve these conventional problems and accurately position electro-mechanical energy conversion elements such as stacked piezoelectric element plates.

[Means for Solving the Problems] A configuration for achieving the object of the present invention is to stack a plurality of electro-mechanical energy conversion elements that expand and contract in the thickness direction on a rod-shaped elastic body with a power supply member interposed therebetween. By applying an alternating current electric field to the plurality of electro-mechanical energy conversion elements in the vibrator which is clamped and fixed in the state, the vibrations of the same-shaped bending motes are excited in the plurality of different planes in the vibrator, and In an ultrasonic motor that causes particles on the surface of the elastic body to perform circular or elliptical motion by providing an appropriate phase difference, and causes relative movement between the elastic body and a member pressed against the elastic body by frictional drive, The power supply member is characterized in that it has a positioning means for regulating the position of the electro-mechanical energy conversion element that comes into contact with the power supply member within a plane perpendicular to the axial direction of the elastic body.

[Function] The ultrasonic motor configured as described above can position the relative phase between the electro-mechanical energy conversion elements such as stacked piezoelectric element plates using a power supply member such as an electrode plate,
For example, when piezoelectric element plates of the same shape are shifted by 90 degrees,
When positioning means are provided on both sides of the electrode plate, the positions of these positioning means may be shifted by an angle of 90°.

[Embodiments] The present invention will be described in detail below based on embodiments shown in the drawings.

Embodiment 1 FIG. 1 is an exploded perspective view showing Embodiment 1 of an ultrasonic motor according to the present invention, and FIGS. 1A and 1B are views of a vibrator viewed from opposite directions.

The vibrator in this embodiment has the same basic structure as the conventional example shown in FIG. 8, and the same members are given the same reference numerals and their explanation will be omitted, and only the different parts will be explained.

In this embodiment, the piezoelectric element plates 30 and 40, which are stacked with the electrode plate 5o in between, have electrodes 8i on both sides of the diameter portion on the front side.
a, b are formed, and a small-diameter through hole 31 is formed axially symmetrically in the insulating part d at the diameter part recessed by the thickness of the electrode.
．． 41 are formed in pairs.

On the other hand, a convex portion 51 that fits into the pair of through holes 31, 31 of the piezoelectric element plate 30 is formed on the surface of the electrode plate 50, and a pair of through holes of the piezoelectric element plate 40 is formed on the back surface of the electrode plate 5o. 41
A convex portion 52 is formed to fit into the convex portion 52 .

A pair of convex portions 51 formed on both the front and back surfaces of the electrode plate 50, respectively.
and 52 are formed with an angular offset of 90'' about the axis.

That is, the piezoelectric element plate 30.
40, each through hole 31.41 of the piezoelectric element plate 30.40 fits into the convex part 51.52 of the electrode plate 50, and the piezoelectric element plates 30 and 40 on both sides sandwiching the electrode plate 50 are aligned with each other. They are aligned and stacked with a positional phase of 90'' centering on the center.

Therefore, when driven by the piezoelectric element plates 30 and 40, efficient driving force can be obtained, and motor efficiency is improved.

Example 2 FIG. 2 shows a second embodiment of the present invention.

In this embodiment, a single piezoelectric element plate 60 is formed into a semicircular shape, which is equivalent to dividing the piezoelectric element plate 30°40 of Example 1 into two at its diameter. and two of these are combined to form one piezoelectric element plate,
A semicircular groove 61 corresponding to the through hole 31.4i of the piezoelectric element of the first embodiment described above is formed in the end face of the piezoelectric element plate 60 that is abutted against each other.

In addition, the piezoelectric element plate 60 is processed with the front side as a (+) electrode, so when two piezoelectric element plates 60 are butted together to form one piezoelectric element, one must be turned over. If combined, the piezoelectric element plate of Example 1 and 30.
A piezoelectric element plate equivalent to 40 is obtained.

When a semicircular piezoelectric element plate is used in this manner, there is an advantage that the polarization process only needs to be performed in one direction, rather than in both the plus (+) and minus (-) directions.

Embodiment 3 FIG. 3 is an exploded perspective view showing Embodiment 3 of the ultrasonic motor according to the present invention, and FIGS. 3(a) and 3(b) are views of the vibrator seen from opposite directions.

In this embodiment, two piezoelectric element plates 30 and 30' are grouped together as a first piezoelectric element section for driving, and two piezoelectric element plates 40 and 40' are grouped as a second piezoelectric element section for driving. The piezoelectric element portion has a higher admittance than that of the first embodiment described above and can be driven at a low voltage. Note that the reason for the increase in admittance will be omitted.

The first piezoelectric element part and! The second piezoelectric element portions are arranged so that the insulating portions d of the piezoelectric element plates coincide with each other, and electrode plates are respectively arranged on the back side of each piezoelectric element plate 30 and 30' constituting the first piezoelectric element portion. At 50 degrees, a convex portion 51' that fits into the through hole 31 of the piezoelectric element plate 30 is formed on the front surface thereof.

Note that the terminal portion 53 of the electrode plate 50′ is connected to the convex portion 51′.
They are formed with a positional phase shift of 90°.

Also, regarding each piezoelectric element plate 40 constituting the second piezoelectric element part, convex portions 51'' are formed on the front surface of the electrode plates 50'' respectively disposed on the back side thereof, similarly to the first piezoelectric element part.
The through hole 41 is fitted into the electrode plate 50.
``terminal portion 53'' is formed at a position where the positional phase with respect to the convex portion 51'' is 0.

And, the first piezoelectric element part and the second piezoelectric element part are!
Terminal part 53° of electrode plate 50° and terminal part 53 of electrode plate 5o''
A jig (not shown) is used to adjust the positional phase to 0° so that the positional phase becomes O'. At this time, the piezoelectric elements 30.30' and 40.40° are shifted by 90° in position. Also, by using one type of electrode plate and shifting the terminal portions of the electrode plates by 90°, the positional phase between the piezoelectric elements 30°30' and 40.40° can be set to 90@.

In this embodiment, each of the first and second piezoelectric element sections is composed of two piezoelectric element plates, but it may be more than that, and the number of electrode plates increases accordingly. 1t8i of the electrode plate of the first piezoelectric element part and the second piezoelectric element part
You can adjust the positional phase difference between the piezoelectric elements to a predetermined phase by simply positioning the plate, or conversely, you can arbitrarily adjust the positional phase difference between the piezoelectric elements by positioning the electrode plate. You can decide.

Embodiment 4 FIG. 4 shows an exploded perspective view of Embodiment 4, and FIG. 90° positional phase difference
It is possible to adjust the position by changing the angle of the
With this electrode plate 70, as shown in FIG.
Half-divided semicircular piezoelectric element plate 60 of Example 2 shown in the figure
It has also been designed to be compatible with

That is, the electrode plate 70 has a concave groove 71 on one orthogonal diameter section at the center for fitting into the insulating section d of the rear piezoelectric element plate 4, and a front groove on the other diameter section. A protruding strip 72 is formed to fit into the insulating part d of the piezoelectric element plate 3, and as shown in FIG. 4(a), the piezoelectric element plates 3 and 4 are
By sandwiching the electrode plate 70 between the piezoelectric element plates 3 and 4 so that their divided electrode sides face each other, piezoelectric element plates 3 and 4 can be arranged with a 90° positional phase shift.

In addition, for the semicircular piezoelectric element plate 6o,
), it is only necessary to align the end faces of the diameter portions of the piezoelectric element plate 7o with the grooves 71 and the protrusions 72 of the electrode plate 7o, respectively.

Example 5 FIG. 5 shows Example 5, and shows an exploded perspective view of a piezoelectric element plate and an electrode plate.

In this embodiment, a notch base portion 92 is formed opposite to the inner peripheral surface of the center hole 91 of the piezoelectric element plate 90.90° arranged on both sides of the electrode plate 80, and Engagement claws 82 and 83 are formed at an interval of 90° to face each other on the inner peripheral edge and extend back and forth in the axial direction. A pair of engaging pawls 83 that engage the notch portions 92 of and extend rearward in the axial direction.
By engaging the cut-out trunk 92 of the rear piezoelectric element 90' with the rear piezoelectric element 90', the two piezoelectric element plates 90 to be stacked can be positioned.

Example 6 FIG. 6 shows Example 6, and shows an exploded perspective view of a piezoelectric element plate and an electrode plate.

In the fifth embodiment described above, the piezoelectric element plate is provided with a notch for positioning, but in this embodiment, on the contrary, the piezoelectric element plate
00, 101 are formed with positioning projections 102 facing each other, and the electrode plate 110 has a pair of opposing claw-like claws that respectively engage with the positioning projections 102 of the piezoelectric element plate 100101 arranged before and after the electrode plate 110. Recesses 111 and 112 are formed, respectively.

Then, the positioning protrusion 10 of the front piezoelectric element plate 100
2 into the claw-like recess 111 of the electrode plate 110, and also the positioning protrusion 102 of the rear piezoelectric element plate 101 by 't8i'.
By engaging the claw-shaped recesses 112, the stacked piezoelectric element plates 100 and 101 are positioned, for example, by aligning the claw-shaped recesses 111 and 112 of the electrode plate 110 with a positional phase of 90''. By providing this, piezoelectric element plates 100 and 101 can be arranged with a 90° positional phase difference.

FIG. 7 is a system configuration diagram when a motor according to the present invention is used to drive an optical lens barrel. 16 is a spring post portion, 17 is a rotating insulating member, and 18 is a coil spring, and the rotor 8 is pressurized by the spring post portion 16 and the coil spring 18. Rotation of the rotor 8 is insulated by a rotation insulating member 17 such as a bearing, and the spring post 16 does not rotate.

A gear 19 is coaxially connected to the rotor 8, and transmits rotational output to the gear 20, thereby rotating a lens barrel 21 having a gear that meshes with the gear 2o.

In order to detect the rotational position and rotational speed of the rotor 8 and the lens barrel 21, an optical encoder slit plate 22 is connected to the gear 20.
The photocoupler 23 detects the position and speed.

[Effects of the Invention] As explained above, according to the present invention, an electric-mechanical energy converting element such as a piezoelectric element plate can be positioned at a predetermined position with respect to a power supply member such as an electrode plate, for example. By setting the phase of the positioning means provided on both sides of the electrode plate at a predetermined angle, it becomes possible to set the positional phase difference between the piezoelectric element plates that are in contact with both sides to a predetermined angle.
Efficient driving force can be obtained from each piezoelectric element plate, and motor efficiency can be improved.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a first embodiment of an ultrasonic motor according to the present invention, and FIGS. 1A and 1B are views of a vibrator viewed from opposite directions. FIG. 2 is a perspective view showing a piezoelectric element of Example 2. FIG. 3 shows Example 3, and FIGS. 3(a) and 3(b) are views of the vibrator viewed from opposite directions. Figure 4 shows Example 4, where (a) is a perspective view showing an example applied to a conventional piezoelectric element plate, and Figure (b) is a perspective view showing an example applied to the piezoelectric element plate of Example 2. It is a perspective view showing an example. Fig. 5 is an exploded perspective view showing Embodiment 5, and Fig. 6 is Embodiment 6.
FIG. FIG. 7 is a diagram showing an optical lens barrel drive mechanism using an ultrasonic motor as a drive source according to the present invention. FIG. 8 is an exploded perspective view of a conventional ultrasonic motor, FIG. 9 is a driving waveform diagram thereof, and FIG. 10 is a sectional view thereof. 16... Spring post 17... Rotating insulating member 18
...Coil spring 19...Gear 20...Gear
21... Lens barrel 22... Optical encoder slit plate 23... Photo coupler 30, 40... Piezoelectric element plate 50... Electrode plate 31,
41...Through hole 51.52...Protrusion 60...
・Piezoelectric element plate 61...Groove portion 53...Terminal portion
70... Electrode plate 71... Concave groove 72.
...Convex strip 80...Electrode plate 82.83...Engaging claw 90...Piezoelectric element plate 91...Center hole 92.
...Notch part 100.101...Piezoelectric element plate 1
10... Electrode plate 111.112... Claw-shaped recess and 4 others l112 Figure bl (CI) Figure 4 (b) et al. Figure 10

Claims (1)

[Scope of Claims] 1. A plurality of electro-mechanical energy conversion elements in a rod-shaped elastic body, in which a plurality of electro-mechanical energy converting elements that expand and contract in the thickness direction are sandwiched and fixed in a laminated state with a power supply member interposed therebetween. By applying an alternating electric field to the energy conversion element, the vibration of the same bending mode is excited in a plurality of different planes in the vibrator, and by giving an appropriate phase difference in time, the elastic body is In an ultrasonic motor that causes surface particles to perform a circular or elliptical motion and causes the elastic body and a member pressed against the elastic body to move relative to each other by frictional drive, the power supply member is an electric-mechanical motor that is in contact with the power supply member. An ultrasonic motor comprising a positioning means for regulating the position of the energy conversion element in a plane perpendicular to the axial direction of the elastic body. 2. The ultrasonic motor according to claim 1, wherein the positioning means is provided with a protrusion on the power supply member that fits into a hole formed in the electro-mechanical energy conversion element. 3. In claim 1, the positioning means is characterized in that the power feeding member is provided with an engaging portion that engages with a groove-shaped insulating portion between the divided electrodes formed on one side of the electro-mechanical energy conversion element. ultrasonic motor. 4. The ultrasonic motor according to claim 1, wherein the positioning means is provided with a convex portion on the power supply member that abuts the electro-mechanical energy conversion element divided into a plurality of parts to form a predetermined gap. 5. The ultrasonic motor according to claim 1, wherein the positioning means includes a convex portion or a concave portion on the power supply member that engages with a concave portion or a convex portion formed on the electro-mechanical energy conversion element. 6. The ultrasonic motor according to claim 1, 2, 3, 4 or 5, wherein the power supply member has positioning means for the electro-mechanical energy conversion elements laminated on both surfaces thereof. 7. The ultrasonic motor according to claim 1, 2, 3, 4, or 5, wherein the power supply member has positioning means only for the electro-mechanical energy conversion element that comes into contact with one surface thereof. 8. The device including the ultrasonic motor according to claim 1, 2, 3, 4, 5, 6, or 7, further comprising an output member that obtains a driving force from a member that is pressed by a vibrator and driven by friction. A device that does this.