JPS62293977A - Ultrasonic motor - Google Patents

Abstract

PURPOSE:To realize a drive without loss by making a fixed part of a node of vibration and its vicinity in a distribution of distortion generated in a vibrator. CONSTITUTION:On a surface of first piezoelectric vibrator 3 are arranged, for example, eight electrodes 3a and a full-face electrode is formed on a back of said vibrator 3. A second piezoelectric vibrator 4 is also constituted in like manner. The first and second piezoelectric vibrators 3, 4 are provided by superposition to an elastic body 2. On a surface of fixing member 5 are formed projections 5a, 5b for fixing by glued connection in the vicinity of a node circle position of the elastic body 2. If an AC output signal is applied to the electrodes of the first and second piezoelectric vibrators 3, 4, the mover 1 will be rotated.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention Field of Industrial Application The present invention relates to an ultrasonic motor that generates driving force using an electro-mechanical energy conversion vibrator such as a piezoelectric body.

BACKGROUND OF THE INVENTION In recent years, ultrasonic motors have attracted attention as motors that do not require windings or magnets and have high torque when rotating at low speeds, compared to conventional electromagnetic motors.

An example of the conventional ultrasonic motor mentioned above will be described below with reference to the drawings.

FIG. 5 shows the structure of a conventional ultrasonic motor.

A vibrating body is constructed by stacking a circular elastic body 2 and two circular piezoelectric vibrators 3.4 in the thickness direction. circular moving body 1
is a flanged bearing 16 and two spring washers 1
7. The vibrating body is brought into pressure contact with the vibrating body by a pressurizing body made by stacking the nut 19 and the nut 19 in the thickness direction.

The surface of the vibrating body has a ring-shaped protrusion 2a for applying vibration energy, and rotational force is obtained by applying electrical signals out of phase with each other to the piezoelectric vibrators 3 and 4. ing. Reference numeral 5 denotes a fixing member using a cushioning material such as felt, which is adhesively bonded to the vibrating body in a layered manner in the thickness direction, and absorbs mechanical motion.

Problems to be Solved by the Invention However, in the above configuration, the vibrating body and the fixed member are integrated by adhesive bonding, so the fixed member becomes a load on the vibrating body. Furthermore, since the adhesive is used for fixing, there is a large loss of imaging energy, which is the driving force of the motor, due to absorption by the adhesive material. In addition, the fixed part is
This has had the problem that stress concentration tends to cause peeling due to mechanical imaging.

Furthermore, when the motor is started and stopped, the fixing member is subjected to a large inertial force, which has a negative effect on stopping accuracy due to the elasticity of the shock absorber used as the fixing member.

Means for Solving the Problems In order to solve the above problems, the ultrasonic motor of the present invention has the following features:
This structure uses the vicinity of the node of longitudinal vibration strain generated in the vibrating body as a fixing part, and fixes it by a mechanical joining method, a method such as adhesion or welding, or a method using a combination of the above-mentioned joining methods.

According to the present invention, with the above-described configuration, the fixed member does not vibrate together with the vibrating body as in the conventional case, so that the ultrasonic motor can be driven with less loss.

Furthermore, since the amplitude at the fixed portion is zero, one of the causes of joint breakage is eliminated. Furthermore, since it is possible to completely confine mechanical vibrations within the motor without using a buffer as a fixed member, the degree of freedom in joining the vibrating member and the fixed member increases. Therefore, it is possible to improve the stopping accuracy and the breaking strength of the fixed portion.

EXAMPLES Below, the ultrasonic motor of the present invention will be explained with reference to the drawings.

FIG. 1 shows the configuration of an ultrasonic motor in a first embodiment of the present invention.

In FIG. 1, on the surface of a first piezoelectric vibrator 3 having a circular shape with a small hole in the center, eight electrodes 3a divided into areas of, for example, 45 degrees are arranged. This electrode 3a is made of a conductive material such as silver, and is made of a conductive material such as silver.
It is formed on the surface of the piezoelectric sensor 4. The electrodes (not shown) provided on the back surface are not divided like the front surface electrodes (they are full-surface electrodes. Adjacent electrodes of the first piezoelectric vibrator 3a configured as described above) Polarization is performed so that the polarization directions are different from each other in the plate thickness direction.As a result, as shown in Figure 1, there are 8 poles, 4 &fl, consisting of regions alternately having positive polarity or negative polarity.
camera element is configured. After polarization, the electrodes 3a do not need to be divided and are connected so that a voltage can be applied all at once. The second piezoelectric vibrator 4 having a circular shape with a small hole in the center hole has the same structure as the first piezoelectric vibrator 3, and consists of an 8-pole, 4Mi vibrator having alternately positive and negative polarities. ing.

The minimum amplitude position of the first piezoelectric vibrator 3 or the second piezoelectric vibrator 4 is near the boundary position between adjacent electrodes, and the minimum amplitude position of the second piezoelectric vibrator 4 is near the center of the electrode, which is the maximum amplitude position. The electrodes are superimposed so that the boundaries between adjacent electrodes, which correspond to amplitude positions, are located.

The first piezoelectric vibrator 3 and the second piezoelectric vibrator 4 configured as described above are attached to overlap with the elastic body 2 having a thickness equal to or about 100 times that of the piezoelectric vibrator. This elastic body 2 is formed into a disk shape using metal such as aluminum, brass, or stainless steel. Further, on the surface of the elastic body 2 serving as the vibrating body, a protrusion 2a serving as an image pickup transmission member is formed in the vicinity of a position of, for example, about 1/2 of the diameter.

Further, the first piezoelectric vibrator 3 and the second piezoelectric vibrator 4 have a maximum outer diameter at a nodal circle position (for example, 33 ml11) that is approximately 5/6 radius with respect to the diameter of the elastic body 2 (for example, 40 n+m).

The structure constructed as described above is used as the vibrating body 6 shown in FIG.

Reference numeral 5 denotes a fixing member according to the present invention, on the surface of which the elastic body 2 is provided.
A protrusion 5a for fixing by adhesive bonding near the nodal position and a protrusion 5b for fixing by adhesive bonding near the nodal point are formed.

The fixing member 5 includes the vibrating body 6 and the protrusion 5a.

5b, it is bonded with an adhesive such as silicone.

As shown in FIG. 2, the output signal oscillated by the oscillator 7 at a driving frequency determined by the vibrating body 6 is branched, one of which is directly sent to the amplifier 8, and the other is sent to the amplifier 1 via a phase shifter 9.
Enter 0. The phase shifter 9 shapes a signal whose phase is shifted within a range of ±10" to ±170 degrees, which is used for forward or reverse rotation. The output signal of the oscillator 7 is directly input to an amplifier 8 and amplified. A signal is applied to the first piezoelectric vibrator 3 through the lead wires 11 and 12.Thereby, the vibrating body 6 is provided with a pair of regions in which the polarization directions of the first piezoelectric vibrator 3 have mutually different positive polarity or negative polarity. Excitation waves with four wavelengths corresponding to eight poles and four sets of vibrators in the circumferential direction are generated.The output of the amplifier 10 is also applied to the second piezoelectric sensor 4 via lead wires 12 and 13. is similarly driven by.

When the vibrating body 6 is driven as described above, the peak of vibration on the side of the vibrating body 6 facing the movable body 1 comes into contact with the movable body 1,
Moreover, since the apex moves with time, a force having a lateral component is applied to the moving body 1. In this way, the movable body 1 repeats positional movement by the lateral component using the drive frequency determined by the vibrating body 6, and as a result, it can obtain rotational motion in the range of approximately several to several thousand revolutions per minute. At this time, the contact position between the vibrating body and the movable body is near the apex of the displacement portion in the positive direction (for example, in the upward direction) of the deflection imaging of the vibrating body 6.

FIG. 3 shows longitudinal strain during driving when an electric signal is applied to the vibrating body 6, and an enlarged sectional view of the vibrating body 6' and the fixing member 5' according to the present invention in a virtual image. The circle is indicated by A1 and the node is indicated by B.

When 50V was applied, a maximum amplitude of about 1.8 μm was exhibited near the protrusion 2a, which is a vibration transmission member.

The phase turning point of the amplitude, so-called vibration node (nodal circle), is located at a position Q1 of 80 to 90%, assuming that the diameter Q is 100%. The fixing member 5' is fixed by a projection 5a at the nodal position and by a projection 5b near the node B using silicone adhesive.

Next, a second embodiment of the present invention will be described with reference to the drawings.

FIG. 4 is a block diagram of an ultrasonic motor showing a second embodiment of the present invention. In the figure, 1 is a moving body, 16 is a bearing with a flange, 17 and 18 are washers, and 19 is a nut, and these pressurizing bodies have the same structure as in FIG. 1. Compared to the configuration shown in FIG. 1, the features of the second embodiment include holes 42c, 42d and notches 43c, 4 for fitting into the elastic body 42, the first piezoelectric body 43, and the second piezoelectric body 44, respectively.
3d.

44c and 44d, and the fixing member 45 is provided with fitting protrusions 45c and 45d.

According to the present embodiment shown in FIGS. 1 and 4, a fixing member that is adhesively bonded with an adhesive such as silicone is used as a fixing part near the nodal point of longitudinal strain of the vibrating body and near the nodal circle. establish. Alternatively, adhesive peeling due to stress concentration could be removed by inserting a press-fitting protrusion into a pressure hole provided in the elastic body. Additionally, by significantly reducing the area of the fixed part, losses due to vibration absorption by the adhesive were significantly reduced. In addition, since the fixed member does not vibrate together with the vibrating body, it is possible to generate larger progressive vibration waves. In addition, the fixing member itself
Since there is no need to absorb mechanical vibrations with a shock absorber, it is now possible to use materials with poor elasticity. This made it possible to improve stopping accuracy. Therefore, it is possible to realize driving of an ultrasonic motor with a simple structure and low loss.

As described above, by using the vicinity of the node of the vibrating body as the fixed part, the degree of freedom in the method of joining the imaging body and the fixed member is increased,
Mechanical joining is now possible. By providing a fixing member for the stator on the ultrasonic motor using a fixing method that uses both mechanical and adhesive bonding, driving with less loss is achieved, and the fixing member is also prevented from receiving damage when the ultrasonic motor is started or stopped. The joint strength of the fixed part is strong against inertial force, and stopping accuracy has been greatly improved.

In the second embodiment, the mechanical joint of the fixing member 45 is located near the nodal circle, but may be located near the nodal point. In addition, although the fixation was performed using a combination of mechanical bonding and adhesive bonding, it is also possible to fix the vibrating body by mechanical bonding alone. If a portion is provided, more effective absorption of mechanical amplitudes can be obtained.

Effects of the Invention As described above, the present invention provides a fixing member that uses the vicinity of the node of longitudinal strain vibration generated in the imaging body as a fixing part, thereby expanding the scope of the method of joining the fixing part and the material of the fixing member. The joint strength of the fixed part can be improved, and the ultrasonic motor can be driven with high stopping precision and low loss.

[Brief explanation of drawings]

FIG. 1 is an exploded perspective view of the configuration of an ultrasonic motor according to the present invention, FIG. 2 is a diagram showing the ultrasonic motor and its drive circuit, and FIG. 3 is a diagram showing the ultrasonic motor according to the first embodiment of the present invention. FIG. 4 is an exploded perspective view of an ultrasonic motor in another embodiment of the present invention;
FIG. 5 is an exploded perspective view of a conventional ultrasonic motor. 1...Moving body, 2...Elastic body, 3, 4
...Piezoelectric vibrator, 5...Fixing member. Name of agent: Patent attorney Toshio Nakao and one other person Figure 1 ■-18 ■-19 Figure 2 Figure 3 - Figure 4 42--(φ', + Main item ■-19 Figure 5 ■-18

Claims (2)

[Claims] (1) A vibrating body consisting of an elastic body and an electro-mechanical energy converter, and a movable body that presses into contact with the vibrating body, with the vicinity of the vibration node of the strain distribution occurring in the vibrating body being a fixed part. ultrasonic motor. (2) The ultrasonic motor according to claim 1, wherein the vibrating body is a disk or a perforated disk, and the vicinity of the nodal circle of the higher-order vibration mode of the vibrating body and the vicinity of the node are both fixed parts.