JP5704846B2 - Vibration type driving device - Google Patents

Description

  The present invention relates to a vibration type driving device called an ultrasonic motor or the like.

As a vibration type driving device such as an ultrasonic motor that drives a driven body with a vibrator, a vibrator in which, for example, a diaphragm formed of a metal elastic member and a piezoelectric element (electro-mechanical energy conversion element) are integrated by bonding or the like Some use
In such a vibration type driving device using a vibrator, a method using magnetic force has been proposed as a method for generating a pressure force between the vibrator and a driven body.
Patent Document 1 proposes a vibration type driving device that includes a permanent magnet in at least a part of a vibrator.
Further, Patent Document 2 proposes a vibration type driving device including a permanent magnet in at least a part of a driven body.
Patent Document 3 proposes a vibration type driving device in which a magnetic member is arranged in a space between a vibrator and a driven body. In the apparatus of Patent Document 3, a protrusion that protrudes from the first surface of the vibrator and contacts the driven body is formed, and a magnet is disposed between the first surface of the vibrator and the driven body. The driven body is configured to be attracted by magnetic force.

JP 2006-340443 A Japanese Laid-Open Patent Publication No. 2005-354787 JP 2007-31519 A

In an ultrasonic motor or the like that applies a pressing force between the vibrator and the driven body using the permanent magnet in the conventional example described above, the mechanism can be simplified as compared with that using a spring. However, the conventional structure that uses magnetic force to generate these pressures has the following problems in the pressure structure when the vibrator and the driven body are brought into pressure contact.
In electronic devices and the like on which an ultrasonic motor is mounted, downsizing and high-density mounting are always required, and further downsizing is also required for the pressure structure of the ultrasonic motor.
On the other hand, the output of the ultrasonic motor, particularly the driving force applied to the driven body by the vibrator, depends on the applied pressure of the vibrator and the driven body.
That is, the driving force with respect to the driven body by the vibrator is transmitted to the driven body through the frictional force caused by the pressure contact with the vibrator, thereby moving the driven body relative to the vibrator.
Therefore, the driving force of the ultrasonic motor depends on the applied pressure that generates the frictional force due to the pressure contact.
For these reasons, there is a need for a pressurizing structure that can achieve downsizing and a necessary pressurizing force, but there is room for further improvement in the above-described conventional one.
Further, in the case where magnetic force is used for generating the pressing force, the pressing force may be unbalanced.
A rotational force about an axis parallel to the relative movement direction of the driven body with respect to the vibrator is generated by the magnetic force. At that time, for example, when there is a positional deviation or inclination due to dimensional accuracy or mounting accuracy, the attractive force increases as the distance between the magnet member and the attracted object gets closer, so the applied pressure can be further unbalanced. There is sex.
Therefore, a structure that does not cause such imbalance of the applied pressure is obtained.

  SUMMARY OF THE INVENTION In view of the above problems, the present invention provides a vibration type driving device that can reduce the pressure structure and obtain the necessary applied pressure, and can stabilize the applied pressure. It is intended.

The vibration type driving device of the present invention has an electro-mechanical energy conversion element and a diaphragm to which the electro-mechanical energy conversion element is joined, and can generate an elliptical motion at a contact portion formed on the diaphragm. A vibrator configured in
A driven body having a driven body that is in pressure contact with the contact portion of the vibrator and moves relative to the vibrator by the elliptical motion,
The first magnetic member is configured by forming at least a part of the driven body from a ferromagnetic material,
A yoke disposed on the opposite side of the vibrator to the driven body side and extending in the relative movement direction, and between the yoke and the vibrator or on the opposite side of the yoke from the vibrator side A second magnetic member is constituted by the permanent magnet provided on the vibrator and the vibrator ;
Wherein the suction force by the magnetic force between the first magnetic member and said second magnetic member, characterized in that the contacting pressure the contact portion of the vibrator to the driven member.

  According to the present invention, it is possible to realize a vibration type driving device that can downsize the pressurizing structure and obtain necessary pressurizing force and can stabilize the pressurizing force.

It is a perspective view explaining the structure of the ultrasonic motor (vibration type drive device) of Example 1 of this invention. It is a perspective view explaining the vibration mode of the vibrator in Example 1 of the present invention. It is the figure shown from each direction explaining the structure of the ultrasonic motor in Example 1 of this invention. (A) is a top view which shows the structure of an ultrasonic motor, (b) is a front view which shows the structure of an ultrasonic motor, (c) is a top view which mainly shows the structure of the part of a yoke in an ultrasonic motor. It is a front view explaining the structure of the ultrasonic motor in Example 2 of this invention. It is a front view explaining the structure of the ultrasonic motor in Example 3 of this invention. It is a perspective view explaining the structure of the ultrasonic motor in Example 4 of this invention.

In the vibration type driving device of the present invention, as described above, the magnetic force lines coming out of the magnet are concentrated, and the yoke for efficiently using the attractive force of the magnet is extended in the direction of relative movement of the driven body. And it is comprised so that the support part of the vibrator | oscillator formed in this vibrator | oscillator and the yoke may be joined.
Since the yoke is arranged along the driven body in this way, a magnetic force can be generated between the yoke and the driven body, and at least a part of the diaphragm forming the vibrator is ferromagnetic. This part can also generate a magnetic pressure with the driven body.
Further, by adopting a configuration in which only the contact portion of the vibrator with the driven body is formed of a ferromagnetic material, it is easy to generate a magnetic attraction force to contact the driven body, and the contact portion is directly applied with pressure. Therefore, it is possible to suppress the generation of rotational force with respect to an axis parallel to the relative movement direction.
Further, by adopting a configuration in which the support portion formed on the vibrator extends in the direction of relative movement of the driven body and is joined to the yoke, the vibrator can be held and fixed by the yoke.
Further, by adopting a configuration in which the joint portion between the support portion and the yoke formed on the vibrator is narrower than the width of the driven body, a large suction force of the yoke can be generated at the joint portion. . This suction force can be brought close to the contact portion, and generation of a rotational force with respect to an axis parallel to the relative movement direction of the driven body can be suppressed.
In addition, a permanent magnet is arranged on the yoke, and a large pressing force is generated by adopting a configuration in which the second magnet extending in the direction of relative movement of the driven body is provided on the permanent magnet arranged on the yoke. Can be made.
That is, a magnetic circuit can be formed by a magnetic member formed on the yoke, the permanent magnet, the second yoke, and the driven body to generate a large pressing force.

Examples of the present invention will be described below.
[Example 1]
As a first embodiment, a configuration example of an ultrasonic motor (vibration type driving device) configured by applying the present invention will be described with reference to FIG.
An ultrasonic motor 10 as a vibration type driving device of the present embodiment mainly includes a vibrator 1 and a driven body 6 held in a pressure contact state with the vibrator 1.
The vibrator 1 includes a piezoelectric element (electro-mechanical energy conversion element) 13 and a diaphragm 11 that is an elastic body to which the piezoelectric element 13 is bonded. The diaphragm 11 is provided with a contact portion 12 that comes into contact with the driven body.
The driven body 6 is made of an iron-based metal that is a ferromagnetic body, and a portion that comes into contact with the vibrator 1 is subjected to a treatment for improving wear resistance such as a nickel plating treatment. This driven body 6 acts as a first magnetic member.
Moreover, the yoke 3 for concentrating a magnetic force line is provided, and this yoke 3 is comprised so that joining to the support part 11-2 (refer Fig.3 (a)) formed in the vibrator | oscillator 1 is possible. In addition, the magnet member 4 is coupled to the yoke 3 in a plane, and the holding member 5 holds and fixes the vibrator 1 to the magnet member 4.
In addition to these, a flexible substrate (not shown) that electrically connects the vibrator 1 and the outside, a guide member of the driven body 6 and the like (not shown) are provided.

To operate the ultrasonic motor 10, an AC voltage is applied to the piezoelectric element 13 to excite the vibrator 1 in two out-of-plane bending modes.
FIG. 2 shows the shape of the vibration mode used at this time. MODE-A is an out-of-plane bending primary mode in which two nodes appear in the vibration part 11 in parallel to the X direction in the figure. Due to the vibration of MODE-A, an amplitude that is displaced in the Z-axis direction (direction perpendicular to the diaphragm 11) is excited in the contact portion. MODE-B is an out-of-plane bending secondary mode in which three nodes appear in the vibration part 11 substantially parallel to the Y direction in the figure. Due to the vibration of MODE-B, an amplitude that is displaced in the X-axis direction (direction parallel to the diaphragm 11) is excited in the contact portion.
By superimposing these two modes, an elliptical motion can be generated on the surface of the contact portion 12.
Then, the driven body is moved relative to the vibrator in the driven body 6 in pressure contact with the contact portion 12 by this elliptical motion.

FIGS. 3A, 3B, and 3C show the ultrasonic motor of FIG. 1 from each direction.
FIG. 3A is a plan view of an ultrasonic motor that mainly explains the configuration of the vibrator 1.
As shown in FIG. 3A, the vibrator 1 includes a diaphragm 11 formed in a plate shape from a paramagnetic metal material such as aluminum.
The diaphragm 11 includes a substantially rectangular vibrating portion 11-1, a coupling portion 11-3 extending so as to face the side surface of the vibrating portion 11-1, and a support portion formed at an end of the coupling portion 11-3. 11-2.
Contact portions 12 formed of a ferromagnetic material such as an iron-based metal are fixed at two locations on the plane portion of the vibrating portion 11-1.
A piezoelectric element 13 (electro-mechanical energy conversion element) is coupled to the other surface of the vibration part 11-1 as shown in FIG.
The vibrator 1 is formed in a substantially symmetrical shape in the X and Y directions shown in FIG. The driven body 6 is disposed on the surface of the vibrator 1 that includes the contact portion 12.
The positions of the vibrator 1 and the driven body 6 are determined so that the centers in the Y direction coincide with each other when projected from the Z direction. The vibrator 1 and the driven body 6 move relative to each other in the X direction.
The support part 11-2 is disposed at a position overlapping the driven body 6 when projected from the Z direction. Further, the support portion 11-2 is formed to be narrower than the driven body 6.

As shown in FIGS. 3B and 3C, the two support portions 11-2 are provided at positions extending in the X direction from the vibrating portion 11-1 of the vibrator, and the two support portions 11. -2 is connected to the opposite side of the side facing the driven body 6 to yoke end portions 3-2 which are both ends of the yoke 3 formed so as to extend in the X direction in the figure.
The width of the yoke end 3-2 is formed to be the same as or narrower than that of the support 11-2. A magnet member 4 is disposed in the vicinity of the piezoelectric element plate 13 of the yoke 3.
Magnet member 4 is magnetized in the Z direction in the figure. A holding member 5 extending in the Y direction in the figure is fixed to the magnet member 4.
The holding member 5 is formed of a phosphor bronze plate, which is a paramagnetic material, and has a leaf spring-like elastic structure. Both ends of the holding member 5 in the Y direction in the figure are held and fixed to a frame (not shown).

A driving member 14 (see FIG. 1) is formed by these components, and a relative movement force in the X direction in the figure is generated between the driving member 14 and the driven body 6.
The drive member 14 is held by the holding member 5, and the elastic structure of the holding member 5 can mainly give a degree of freedom of deformation around the Z direction, X and Y axes in the figure.
For this reason, even if a deviation occurs with respect to the desired positional relationship between the driving member 14 and the driven body 6, a contact state is given so as to follow each other by the magnetic attractive force.
In the present embodiment, the second magnetic member is formed by the magnet member 4, the yoke 3, and the two contact portions 12 made of ferromagnetic material in the driving member 14 described above.
The magnetic force lines coming from the upper surface of the magnet member 4 in the Y direction, that is, from the vicinity of the vibrator, are substantially in the Y direction, and a part thereof passes through the contact portion 12. This magnetic field line passes through the driven body 6 which is the first magnetic member. Further, part of the lines of magnetic force that emerge from the magnet member 4 passes directly through the driven body 6. Part of the lines of magnetic force passing through the driven body 6 goes to the end of the yoke 3 that extends in the X direction. The lines of magnetic force passing through the yoke 3 return to the magnet member 4 joined to the yoke 3.
When the magnetic lines of force pass in this way, the magnetic force of the magnet member 4 can be effectively used for the attractive force between the driving member 14 and the driven body 6.

According to the configuration of the present embodiment described above, the ultrasonic motor can be configured as follows.
By disposing the magnet member 4 in the vicinity of the vibrator, it is possible to reduce the distance from the driven body 6 and obtain a suction force.
Moreover, the contact part 12 can be made into a ferromagnetic body, and the structure which collects the magnetic force which generate | occur | produces from the magnet member 4 to this contact part 12 can be taken.
Moreover, the structure which makes the contact part 12 contact the driven body 6 directly, and generate | occur | produces a suction force effectively can be taken.
Further, the yoke 3 is formed so as to be coupled to the support portion 11-2, the yoke 3 is positioned in the vicinity of the driven body 6, and an attractive force is effectively generated between the driven body 6 and the yoke 3. Can be taken.
Moreover, the structure which makes the yoke 3 and the magnet member 4 contact directly, and concentrates a magnetic force line can be taken.
In addition, it is possible to adopt a configuration in which the yoke is also provided with an action of holding the vibrator 1 and there is no need to separately prepare parts for holding the vibrator 1.
Further, in the drive member 14, the suction force with the driven body 6 is generated mainly by the contact portion 12 and the yoke end portion 3-2, which are portions concentrated near the center in the Y direction in FIG. 3. Can be adopted. Accordingly, even when a displacement in the Y direction occurs between the driving member 14 and the driven body 6, it is possible to suppress the generation of a moment around the X axis due to the magnetic force.
According to the configuration of the present embodiment, it is possible to sufficiently generate the attractive force due to the magnetic force, that is, the pressing force between the driving member 14 and the driven body 6 with a small component.
In addition, it is possible to reduce the bias of the applied pressure caused by the positional deviation between the driving member and the driven body 6.

[Example 2]
As a second embodiment, a configuration example of an ultrasonic motor (vibration type driving device) having a different form from the first embodiment will be described with reference to FIG.
The description of the same configuration as that of the first embodiment shown in FIGS. 1 and 3 is omitted.
In this embodiment, the diaphragm 11 is made of an iron-based ferromagnetic metal. In the case of the present embodiment, the contact portion 12 may be provided by press forming the diaphragm 11 to form a protrusion. Although it may be fixed as a separate member to the diaphragm 11 as in the first embodiment, the process can be simplified and the cost can be reduced by press molding.
The holding member 5, the yoke 3, and the magnet member 4 are arranged in this order from the vibrator 1 downward in the Z direction in the figure.
The yoke 3 has a yoke end 3-2 connected to the vibrator support 11-2 in the same manner as shown in FIG.
In this embodiment, in addition to the magnet member 4, the yoke 3, and the holding member 5, the diaphragm 11 acts as a second magnetic member. Moreover, the yoke 3, the diaphragm 11, and the contact part 12 become the same magnetic pole.
According to the present embodiment, the diaphragm 11 located in the vicinity of the driven body 6 acting as the first magnetic member acts as a magnetic member, so that an attractive force, that is, an application of the driving member 14 and the driven body 6 is applied. The pressure can be generated more effectively.

[Example 3]
As Example 3, a configuration example of an ultrasonic motor (vibration type driving device) in a form obtained by modifying Example 2 will be described with reference to FIG.
In this embodiment, the driven body 6 is formed by coupling a permanent magnet 8 and a friction member 7.
The friction member 7 is used in a state where the hardness is increased by quenching martensitic stainless steel, which is a ferromagnetic material. Here, no magnet member is arranged on the drive member 14.
Similar effects can be obtained even if a permanent magnet is arranged on the first magnetic member side as in this embodiment.

[Example 4]
As Example 4, a configuration example of an ultrasonic motor (vibration type driving device) having a different form from Example 3 in which Example 2 is modified will be described with reference to FIG.
In the present embodiment, the second yoke 9 is disposed on the open surface of the magnet 4 in the form shown in FIG.
Both ends of the second yoke 9 extend in the X direction in the drawing and near the bottom surface of the driven body 6. The width of the second yoke end portion 9-2 is narrower than the width of the driven body 6.
By arranging the second yoke 9 as in the present embodiment, it is possible to further increase the suction force, that is, the applied pressure between the driving member 14 and the driven body 6.
In this embodiment, the diaphragm 11 may be formed of a paramagnetic material.
By using the diaphragm 11 as a paramagnetic material, even when a displacement in the Y direction occurs between the driving member 14 and the driven body 6 as described in the first embodiment, the moment around the X axis due to the magnetic force is increased. Occurrence can be suppressed.

DESCRIPTION OF SYMBOLS 1: Vibrator 3: Yoke 4: Magnet member 5: Holding member 6: Driven body 10: Ultrasonic motor 11: Diaphragm 12: Contact part 13: Piezoelectric element (electro-mechanical energy conversion element)
14: Drive member

Claims (5)

A vibrator having an electro-mechanical energy conversion element and a diaphragm to which the electro-mechanical energy conversion element is joined, and configured to generate an elliptical motion in a contact portion formed on the diaphragm;
A driven body having a driven body that is in pressure contact with the contact portion of the vibrator and moves relative to the vibrator by the elliptical motion,
The first magnetic member is configured by forming at least a part of the driven body from a ferromagnetic material,
A yoke disposed on the opposite side of the vibrator to the driven body side and extending in the relative movement direction, and between the yoke and the vibrator or on the opposite side of the yoke from the vibrator side A second magnetic member is constituted by the permanent magnet provided on the vibrator and the vibrator ;
Wherein the suction force by the magnetic force between the first magnetic member and said second magnetic member, the vibration type driving apparatus according to claim wherein the contacting pressure of the contact portion of the vibrator to the driven member. 2. The vibration type driving device according to claim 1, wherein the contact portion formed on the vibration plate of the vibrator is formed of a ferromagnetic material. The vibrator includes a support portion, and the support portion is formed at a position extending from the vibration portion of the diaphragm in a direction in which the driven body is relatively moved, and extends in a direction in which the driven body is relatively moved. The vibration type driving apparatus according to claim 1, wherein the vibration type driving apparatus is joined to an end portion of the yoke to be taken out. 4. The vibration type driving device according to claim 3 , wherein a joint portion where the support portion and the yoke are joined is configured to be narrower than a width of the driven body.   5. The permanent magnet disposed in the yoke, and a second yoke extending in a direction in which the driven body moves relative to the permanent magnet is provided on the yoke. The vibration type driving device according to any one of the above.

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