JP6221521B2 - Vibration wave motor and optical equipment - Google Patents

Description

  The present invention relates to a vibration wave motor and an optical apparatus.

The vibration wave motor generates a progressive vibration wave (hereinafter abbreviated as traveling wave) on the elastic drive surface using the expansion and contraction of the piezoelectric body, and this traveling wave causes an elliptical motion on the drive surface. The mover in pressure contact with the wave front of the motion is driven. Such a vibration wave motor is characterized by having a high torque even at a low rotation. Therefore, when mounted on a drive device, the gear of the drive device can be omitted, thus eliminating gear noise. This has the advantage of achieving quietness and improving positioning accuracy.
In recent years, the vibration wave motor tends to be reduced in size and weight by reducing the diameter to about 1/3 to 1/5 times that of the conventional motor. Such a miniaturized vibration wave motor is easy to use in the incorporation of devices, has been applied to applications, and has greatly increased the number of shipments (see Patent Document 1).

JP 2006-333629 A

  An object of the present invention is to provide a vibration wave motor and an optical apparatus with improved driving efficiency.

The present invention includes an electromechanical transducer drive signal is input through the electrodes causes a vibration wave by the input of said drive signal to said electromechanical transducer, elasticity of the contact portion for contacting a moving member A first electrode to which a first-phase drive signal for generating a bending vibration in which the position of the contact portion becomes a vibration abdomen is input, and the contact portion The first phase drive is performed while the moving member is being moved. The present invention relates to a vibration wave motor including a control unit that changes a speed of the moving member by changing a magnitude of a signal voltage and a magnitude of a voltage of the second phase drive signal .
The present invention also relates to an optical apparatus provided with the vibration wave motor.

  According to the present invention, it is possible to provide a vibration wave motor and an optical apparatus with improved driving efficiency.

It is the figure which showed the example which mounted the vibration wave motor of this embodiment in the lens barrel. It is a figure explaining the vibration wave motor of a 1st embodiment. It is a figure explaining the shape of an elastic body. It is a figure explaining the piezoelectric material and electrode pattern of a 1st embodiment. It is a block diagram explaining the drive device of a vibration wave motor. It is a figure explaining operation | movement of the vibration wave motor of 1st Embodiment. It is a figure which shows the drive signal A phase and B phase. It is a figure explaining the time-sequential movement of a projection part. It is a figure explaining the piezoelectric material and electrode pattern of 2nd Embodiment. It is a figure explaining operation | movement of the vibration wave motor of 2nd Embodiment.

(First embodiment)
Hereinafter, a first embodiment of a vibration wave motor 1 according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a view showing an example in which the vibration wave motor 1 of the present embodiment is mounted on a lens barrel 100.
The vibration wave motor 1 is attached to a gear unit module 101, and the gear unit module 101 is attached to a fixed cylinder 102 of the lens barrel 100.
The rotational motion of the output gear 2 of the vibration wave motor 1 is transmitted to the cam ring 104 via the reduction gear 103 of the gear unit module 101, and the cam ring 104 is driven to rotate.
A key groove 105 is cut in the cam ring 104 obliquely with respect to the circumferential direction, and the AF ring 107 in which the fixing pin 106 is inserted into the key groove 105 is rotated by the cam ring 104 so that the light It is driven in the straight direction in the axial direction and can be stopped at a desired position.
The circuit 108 is provided between the outer fixed tube 102A and the inner fixed tube 102B of the lens barrel 100, and performs driving and control of the vibration wave motor 1, detection of the number of rotations, and the like.

FIG. 2 is a diagram illustrating the vibration wave motor 1 according to the first embodiment.
In the first embodiment, the vibrator 3 side is fixed, and the relative motion member 4 (moving element) is driven.
As will be described later, the vibrator 3 includes an electro-mechanical conversion element (hereinafter referred to as a piezoelectric body 5) such as a piezoelectric element or an electrostrictive element that converts electrical energy into mechanical energy, and a piezoelectric body 5. A vibration wave is generated in the vibrator 3.

The elastic body 6 is made of a metal material having a high resonance sharpness. 3A and 3B are views for explaining the shape of the elastic body 6, wherein FIG. 3A is a front view and FIG. 3B is a side view. As shown in the drawing, the elastic body 6 has an annular shape.
The elastic body 6 has a base portion 7 and a protruding portion 8.
The protrusions 8 are provided on the upper surface of the base portion 7 equally at six locations in the circumferential direction, and the tip surface of the protrusion 8 becomes the drive surface 8a and is in contact with the relative motion member 4 under pressure. It is. In addition, the piezoelectric body 5 is bonded to the surface of the lower surface of the base portion 7 where there is no protrusion 8.

A flange 7a is extended to the inner diameter side of the base portion 7, and is fixed by a fixing member 9 at the innermost diameter portion of the flange 7a. In FIG. 3, the flange 7a is omitted.
The driving surface 8a of the protrusion 8 of the elastic body 6 is provided with a paint film or a lubricating plating as a sliding member.
As will be described later, two types of out-of-plane bending tertiary vibrations are generated in the base portion 7 of the elastic body 6 along the circumferential direction.
One vibration is a vibration in which the position of the protrusion 8 becomes an abdomen of vibration, and the other vibration is a vibration in which the position of the protrusion 8 becomes a node of vibration. The distance corresponds to 1/2 wavelength of this bending vibration.

The piezoelectric body 5 is composed of lead zirconate titanate called PZT or lead-free materials such as potassium sodium niobate, potassium niobate, sodium niobate, potassium barium titanate, bismuth sodium titanate, titanium You may comprise from bismuth potassium acid etc.
Although the details will be described later on the surface of the piezoelectric body 5, electrodes are arranged, which are divided into two phases (A phase and B phase) along the circumferential direction. In each phase, it is alternately polarized every 1/2 wavelength.
A flexible printed circuit board (FPC) 10 is bonded to the surface of the piezoelectric body 5 opposite to the bonding surface side of the elastic body 6 to extend a circuit 108.
The relative motion member 4 is made of a light metal such as aluminum, and the surface of the sliding surface is subjected to a surface treatment for improving wear resistance.

The output shaft 11 is coupled to the relative motion member 4 via a rubber member 12 and a stopper member 13 inserted so as to fit into the D cut of the shaft.
The output shaft 11 and the stopper member 13 are fixed by an E clip 14 or the like, and rotate integrally with the relative motion member 4. The rubber member 12 between the stopper member 13 and the relative motion member 4 has a function of coupling with the relative motion member 4 and the stopper member 13 due to adhesiveness of rubber, and vibration from the relative motion member 4 is transmitted to the output shaft 11. Butyl rubber having a function of absorbing vibration so as not to transmit is suitable.

  The pressure member 15 is provided between the output gear 2 of the output shaft 11 and the bearing 16. By taking such a structure, the relative motion member 4 is brought into pressure contact with the drive surface 8 a of the vibrator 3.

FIG. 4 is a diagram illustrating the piezoelectric body 5 and the electrode pattern.
An electrode pattern as shown in FIG. 4 is provided on one side of the piezoelectric body 5. In the present embodiment, the illustrated surface 5 a is a surface opposite to the joint surface 5 b with the elastic body 6.
On the other hand, the joint surface 5b of the elastic body 6 is a full-surface electrode so that the elastic body 6 becomes GND.

The electrode pattern is a quarter wavelength of the wavelength of out-of-plane bending vibration, and is arranged in the circumferential direction. The electrode A to which the A phase is input and the electrode B to which the B phase is input are alternately arranged. ing.
The electrode A is configured such that the middle of the electrode is positioned at the protruding portion 8 with respect to the circumferential direction, and the electrode B is disposed between the protruding portion 8 and the protruding portion 8 with respect to the circumferential direction. The middle of is located.

  When only the electrode A is viewed, it is alternately polarized with (+) (−) along the circumferential direction. Further, when only the electrode B is viewed, it is alternately polarized with (+) (−) along the circumferential direction.

In the present embodiment, the piezoelectric body 5 utilizes the d31 piezoelectric phenomenon.
This is a phenomenon in which displacement occurs in the circumferential direction (one direction) when a voltage is applied in the polarization direction (three directions). When a voltage is applied in the thickness direction of the piezoelectric body 5, an expansion displacement and a contraction displacement are generated in the piezoelectric body 5, thereby causing a bending displacement of the elastic body 6 base portion 7. When the drive signal is an AC voltage, out-of-plane bending vibration (standing wave) is generated in the base portion 7.

  Accordingly, the A phase input to the electrode A causes a vibration in which the protrusion 8 is positioned at the antinode of the out-of-plane bending vibration in the base portion 7 of the elastic body 6, and the elastic force is generated by the B phase input to the electrode B. In the body 6 base portion 7, vibration is generated in which the protruding portion 8 is positioned at a node portion of out-of-plane bending vibration.

  FIG. 5 is a block diagram illustrating the driving device 20 of the vibration wave motor 1 of the present embodiment. First, driving / control of the vibration wave motor 1 will be described.

The oscillating unit 22 generates a drive signal having a desired frequency according to a command from the control unit 21.
The phase shifter 23 divides the drive signal generated by the oscillator 22 into two drive signals having a 90 ° phase difference.
The amplification unit 24 boosts the two drive signals divided by the phase shift unit 23 to desired voltages, respectively.
A drive signal from the amplifying unit 24 is transmitted to the vibration wave motor 1. In the vibration wave motor 1, vibration is generated in the vibrator 3 by application of the drive signal, and the relative motion member 4 is driven by the vibration.

The position / velocity detection unit 25 is configured by an optical encoder, a magnetic encoder, or the like, detects the position or speed of a driven object driven by driving the relative motion member 4, and uses the detected value as an electrical signal for the control unit 21. To communicate.
The control unit 21 controls driving of the vibration wave motor 1 based on a driving command from the CPU of the lens barrel 100 or the camera body. The control unit 21 receives the detection signal from the position / speed detection unit 25, obtains position information and speed information based on the value, and controls the frequency of the oscillation unit 22 so as to be positioned at the target position.

The operation of the vibration wave motor 1 of the first embodiment will be described with reference to FIG. 6A shows the vibration in the pressurizing direction, and FIG. 6B shows the vibration in the driving direction.
When a drive command is issued from the control unit 21, a drive signal is generated from the oscillation unit 22. The drive signal is divided into two drive signals (A phase and B phase) having a phase difference of 90 degrees by the phase unit, and is amplified to a desired voltage by the amplification unit 24. FIG. 7 is a graph showing drive signals, where (a) shows the A phase and (b) shows the B phase.

The electrode pattern of the piezoelectric body 5 is divided into an electrode A to which an A-phase drive signal is input and an electrode B to which a B-phase drive signal is input as described in FIG.
Due to the input of the A-phase drive signal to the electrode A, the base portion 7 of the elastic body 6 generates third-order mode vibration (standing wave) in which the protrusion 8 is located at the antinode of the out-of-plane bending vibration (FIG. 5). 6 (a)).
At the same time, due to the input of the B-phase drive signal to the electrode B, the base portion 7 of the elastic body 6 has third-order mode vibration (standing wave) in which the protrusion 8 is located at the node of the out-of-plane bending vibration. It occurs (FIG. 6B).

The vibration in which the protrusion 8 is positioned at the antinode of the out-of-plane bending vibration is vibration that displaces the protrusion 8 in the vertical direction, that is, the pressurizing direction (FIG. 6A).
The vibration in which the protrusion 8 is located at the node of the out-of-plane bending vibration is a vibration that causes the protrusion 8 to rotate, that is, is displaced in the driving direction (FIG. 6B).

FIG. 8 is a diagram for explaining the time-series movement of the protrusion 8 (81, 82). (A) shows the movement of the protrusion 81, and (b) shows the movement of the protrusion 82 arranged next to the protrusion 81.
The protrusion 81 is
When t = 1, it moves upward,
When t = 2, move to the right,
When t = 3, it moves downward,
When t = 4, move to the left,
When t = 5, it moves upward, that is, when t = 1.
Thus, the drive surface 81a of the protrusion 81 generates an elliptical motion.

The protrusion 82 next to the protrusion 81 is
When t = 1, move downward,
When t = 2, move to the left,
When t = 3, it moves upward,
When t = 4, move to the right,
When t = 5, it moves downward, that is, when t = 1.
In this way, the drive surface 82a of the protrusion 82 also generates an elliptical motion.
The protrusions 81 and the protrusions 82 are alternately positioned, and the elliptical motions of each other appear to be 180 degrees out of phase.

In the present invention, the structure of the vibrator 3 becomes very simple by arranging the protruding portions 8 (81, 82) on the base portion 7 and joining one piezoelectric body 5.
As a result, only vibrations necessary for driving can be excited, and driving force and driving efficiency can be greatly improved as compared with the conventional structure.
In addition, the number of parts is greatly reduced and the number of assembly steps is greatly reduced, so that a significant cost reduction can be achieved.
The vibration wave motor 1 of the present invention is a system that generates vibration in the pressurizing direction by the A-phase input and generates vibration in the drive direction by the B-phase input. You can control the size and shape.

As a comparison, a traveling wave type vibration wave motor will be described as an example. Speed control is mainly performed by frequency and voltage, but if the frequency is increased (or decreased) to reduce the speed, the driving direction of the elliptical motion In addition to this, the pressurizing direction is also reduced.
For this reason, depending on the surface roughness and flatness of the drive surface 8a at a low speed, the rotation unevenness may increase or stop suddenly.

  If the frequency is lowered (or the voltage is increased) to increase the speed, not only the driving direction of the elliptical motion but also the pressurizing direction becomes large, and the vibration in the low pressurizing direction becomes too large, so that abnormal noise is generated. May occur or power consumption may increase.

On the other hand, the vibration wave motor 1 of this system maintains the A-phase voltage when the speed is lowered, and if the B-phase voltage is lowered, the amplitude in the pressurizing direction is ensured while the amplitude in the driving direction is secured. Can be reduced (in this state, the ellipse has a vertically long shape), and ultra-low speed driving becomes possible.
Also, when the speed is increased, if the A-phase voltage is maintained and the B-phase voltage is increased, only the amplitude in the driving direction can be increased (in this state, the ellipse has a horizontally long shape). As compared with the traveling wave type, no abnormal noise is generated even at a high speed, and the power consumption can be suppressed.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. The second embodiment differs from the first embodiment in the electrode pattern of the piezoelectric body 5A. FIG. 9 is a diagram illustrating the piezoelectric body 5A and the electrode pattern of the second embodiment. The appearance of the vibration wave motor, the appearance incorporated in the lens barrel 100, and the drive circuit 108 are the same as those in the first embodiment, and thus the description thereof is omitted.

An electrode pattern as shown in FIG. 9 is provided on one side of the piezoelectric body 5A.
In the second embodiment, the illustrated surface 5 </ b> Aa is a surface opposite to the joint surface with the elastic body 6.
On the other hand, the joint surface of the elastic body 6 is a full-surface electrode as in the first embodiment, and the elastic body 6 is set to GND.

The electrode pattern is half the wavelength of the out-of-plane bending vibration, and the electrode A to which the A phase is input is disposed on the inner side, and the electrode B to which the B phase is input is disposed on the outer side.
In the electrode A, the center of the electrode is located at the protrusion 8A with respect to the circumferential direction.
In the electrode B, the middle of the electrode is located between the protrusion 8A and the protrusion 8A with respect to the circumferential direction.

  When only the electrode A is viewed, it is alternately polarized with (+) (−) along the circumferential direction, and when only the electrode B is viewed, it is alternately polarized with (+) (−) along the circumferential direction. Yes.

Due to the input of the A phase to the electrode A, vibration occurs in the base portion 7 of the elastic body 6 in which the protrusion 8 is located at the antinode of the out-of-plane bending vibration, and due to the input of the B phase to the electrode B, the elastic body 6 In the base portion 7, vibration is generated in which the protruding portion 8 is positioned at a node portion of out-of-plane bending vibration.
In the second embodiment, the d31 piezoelectric phenomenon is also used.

The operation of the vibration wave motor according to the second embodiment will be described with reference to FIG. FIG. 10A shows vibration in the pressurizing direction, and FIG. 10B shows vibration in the driving direction.
Similarly to the first embodiment, when a drive command is issued from the control unit 21, a drive signal is generated from the oscillation unit 22. The drive signal is divided into two drive signals (A phase and B phase) having a phase difference of 90 degrees by the phase shift unit 23 and amplified to a desired voltage by the amplifier unit 24. The drive signals A phase and B phase are the same as in FIG. 7 of the first embodiment.

As described above, the piezoelectric body 5A is divided into the electrode A to which the A-phase drive signal is input and the electrode B to which the B-phase drive signal is input.
The drive signals A phase and B phase are applied to the electrodes A and B of the piezoelectric body 5A, respectively. Then, due to the input of the A phase to the electrode A, tertiary mode vibration is generated in the base portion 7 of the elastic body 6 in which the protruding portion 8A1 is located at the antinode of the out-of-plane bending vibration. Due to the input of the B phase to the electrode B, the base portion 7 of the elastic body 6 generates third-order mode vibration in which the protrusion 8A2 is located at the node of the out-of-plane bending vibration.
The vibration in which the protrusion 8 is positioned at the antinode of the out-of-plane bending vibration is vibration that displaces the protrusion 8 in the vertical direction, that is, in the pressurizing direction (FIG. 10A). The vibration in which the protrusion 8 is positioned at the node of the out-of-plane bending vibration is a vibration that rotates the protrusion 8, that is, is displaced in the driving direction (FIG. 10B).

  Also in the present embodiment, the structure of the vibrator 3 becomes very simple due to the configuration in which the protruding portion 8A (8A1, 8A2) is arranged on the base portion 7 and the single piezoelectric body 5 is joined, which is necessary for driving. It is possible to excite only the vibration. As a result, the driving force and the driving efficiency can be greatly improved as compared with the conventional structure.

In addition, the number of parts is greatly reduced and the number of assembly steps is greatly reduced, so that a significant cost reduction can be achieved.
In the first embodiment, the electrode pattern has a quarter wavelength with respect to the circumferential direction. However, in the second embodiment, both the A phase and the B phase have 1 electrode pattern in the circumferential direction. / 2 wavelength can be secured. For this reason, since the excitation of bending vibration is more advantageous than in the first embodiment, it is possible to improve the driving force.
In addition, as in the first embodiment, the vibration in the pressurizing direction is generated by the A-phase input and the vibration in the driving direction is generated by the B-phase input. You can control the size and shape of the exercise.

  As described above, in the above-described embodiment, the protrusions 8 and 8A are provided at six locations, and the in-plane tertiary bending vibration mode is described as an example. However, it is not limited to this combination. For example, although the driving performance is inferior, the protrusion 8 can be driven at three locations even in the in-plane tertiary bending vibration mode.

  The protrusions 8 and 8A are preferably three or more in order to ensure contact with the sliding surface of the relative motion member 4.

  In terms of driving performance, bending vibration of the order of (number of protrusions / 2) is preferable. For example, if the number of protrusions is 8, quaternary bending vibration is suitable. If the number of protrusions is 10, fifth-order bending vibration is preferable. Since the third-order bending vibration can increase the amplitude, it is more advantageous than the case where the vibration order is large.

  In the embodiment, the protrusions 8 and 8A are provided, and the drive surface 8a of the protrusions 8 and 8A is in contact with the sliding surface of the relative motion member 4, but the present invention is not limited to this. For example, the protrusions 8 and 8A may not be provided, and the surface of the base portion 7 may be in direct contact with the sliding surface of the relative motion member 4.

  1: vibration wave motor, 3: vibrator, 4: relative motion member, 5: piezoelectric body, 6: elastic body, 7: base portion, 8: protrusion, 8a: driving surface, 20: driving device, 81: protrusion Part, 100: lens barrel, A: electrode, B: electrode

Claims (12)

An electromechanical transducer to which a drive signal is input via an electrode;
Resulting vibration wave by the input of the driving signal to the electromechanical conversion element, and an elastic member having a contact portion for contacting a moving member,
The electrode of the electromechanical conversion element includes a first electrode to which a first-phase driving signal for generating a bending vibration in which the position of the contact portion is a vibration antinode and a position of the contact portion is a vibration node. A second phase driving signal for generating a bending vibration that becomes a part is separated from the second electrode ,
A control unit configured to change the speed of the moving member by changing the magnitude of the voltage of the first-phase driving signal and the voltage of the second-phase driving signal while moving the moving member; Vibration wave motor. The vibration wave motor according to claim 1,
The contact portion Doha motor vibration that provided three or more. In the vibration wave motor according to claim 1 or 2,
The vibration is a plane bending vibration position of the contact portion is in the abdomen of the vibration, Doha motor vibration position of the contact portion is Ru vibration der bending plane would node portions of vibration. In the vibration wave motor according to claim 3,
The out-of-plane bending vibrations Doha motor vibration Ru vibration der the third mode. The vibration wave motor according to any one of claims 1 to 4 ,
The contact portion moves in a direction substantially perpendicular to the driving direction by out-of-plane bending vibration that becomes an abdomen of the vibration,
The contact portion by plane bending vibration becomes node portion of the vibration, Doha motor vibration you move in the driving direction. An electromechanical transducer in which a first-phase drive signal is input via the first electrode, and a second-phase drive signal is input via the second electrode disposed between the two first electrodes;
An elastic body that generates a vibration wave by inputting a drive signal to the electromechanical transducer;
A moving member that moves by the vibration wave;
A controller that changes the speed of the moving member by changing the magnitude of the voltage of the first phase driving signal and the magnitude of the voltage of the second phase driving signal while moving the moving member;
A vibration wave motor comprising: The vibration wave motor according to any one of claims 1 to 6,
The controller is a vibration wave motor that slows the moving speed of the moving member by making the magnitude of the voltage of the second phase drive signal smaller than the magnitude of the voltage of the first phase drive signal. The vibration wave motor according to any one of claims 1 to 6,
The controller is a vibration wave motor that increases the moving speed of the moving member by making the magnitude of the voltage of the second phase drive signal larger than the magnitude of the voltage of the first phase drive signal. The vibration wave motor according to any one of claims 1 to 8 ,
The electro-mechanical conversion element is annular Doha motor vibration and the second electrode and the first electrode along the circumference that are arranged alternately. The vibration wave motor according to any one of claims 1 to 9 ,
The electro-mechanical conversion element is annular, inner peripheral side of the first electrode is disposed, Doha motor vibration that has the second electrode is disposed on the outer peripheral side. The vibration wave motor according to any one of claims 1 to 10 ,
The Doha motor vibration that have a phase difference of 90 ° to the drive signal for the first phase of the drive signal and the second phase. An optical apparatus comprising the vibration wave motor according to any one of claims 1 to 11 .

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