JP5985013B2 - Motor and lens barrel - Google Patents

Description

The present invention relates to a motor using a vibrator that generates vibration .

  Conventionally, for example, an ultrasonic motor has been adopted as a drive source for a camera or a lens by utilizing features such as silent operation, driving from low speed to high speed, and high torque output. The ultrasonic motor disclosed in Patent Document 1 includes an annular driven body having a rotating shaft and a plurality of vibrators, and the vibrator is in an annular shape in a frictional contact state pressurized against the driven body. On the driven body at a predetermined interval. When ultrasonic vibration is excited in the vibrator in the frictional contact state, an elliptical motion is generated in a portion of the vibrator that is in contact with the driven body, and the driven body is driven to rotate about the rotation axis. The pressure applied to the driven body of the vibrator is obtained by urging the vicinity of the neutral axis corresponding to the vibration node set near the center of the vibrator with a leaf spring via a holder member and a pressing member. The applied pressure is adjusted by a screw and an adjustment washer provided in the vicinity of the fixed portion of the leaf spring.

Japanese Patent No. 4667839

  However, the vibrator holding mechanism in the ultrasonic motor disclosed in Patent Document 1 described above has many components and is complicated. In particular, it is necessary to provide a support shaft in the vicinity of the neutral axis of the vibrator in order to hold the vibrator in a stable pressurized state against the driven body, and the number of parts is large and assembly is complicated. Further, since a large piezoelectric element is used, the cost is high.

(Object of invention)
An object of the present invention is to stably transmit the force of a pressurizing means to a vibrator with a simple configuration and suppress the occurrence of abnormal noise in an audible range in a motor using a vibrator that generates vibration .

In order to achieve the above object, a motor according to the present invention transmits a vibrator that generates vibration, a first member that holds the vibrator, a pressure unit, and a force of the pressure unit. and a second member, the front Symbol first member, attenuation for vibration of the vibrator than the second member is characterized in the us go magnitude.

According to the present invention, in a motor using a vibrator that generates vibration, it is possible to stably transmit the force of the pressurizing unit to the vibrator with a simple configuration and to suppress the generation of abnormal noise in the audible range. is there.

1 is a perspective view illustrating an entire ultrasonic motor that is Embodiment 1 of the present invention. FIG. It is a perspective view which shows the state which decomposed | disassembled the ultrasonic motor of Example 1. FIG. 4 is an enlarged perspective view for explaining a connection state of the diaphragm 102 and the first holding member 104 in Embodiment 1. FIG. It is an expanded sectional view showing the state where each member of Example 1 was incorporated. It is an expanded sectional view showing the state where rotor 101 of Example 1 inclined. It is an expanded sectional view which shows the state which incorporated each member of Example 2 of this invention.

  The mode for carrying out the invention is as described in Examples 1 and 2 below.

  Embodiment 1 of the present invention will be described below with reference to FIGS. The ultrasonic motor according to the first embodiment is an example of a rotary drive motor unitized as a drive actuator such as a lens barrel for a digital camera.

  1 and 2 are diagrams showing an ultrasonic motor that is Embodiment 1 of the present invention. FIG. 1 is a perspective view showing the entire ultrasonic motor, and FIG. 2 is a perspective view showing a state in which the ultrasonic motor of FIG. 1 is disassembled. In each figure, the same member is shown with the same numerals.

  Reference numeral 101 denotes a rotor corresponding to the driven body of the present invention, which includes a contact surface 101a with which a vibrator described later comes into frictional contact. Reference numeral 102 denotes a diaphragm that is pressed and held in contact with the contact surface 101a. Reference numeral 103 denotes a piezoelectric element that is pressure-bonded to the diaphragm 102 with an adhesive or the like. An elliptical motion can be generated by applying a voltage in a state where the diaphragm 102 and the piezoelectric element 103 are pressed. The vibrator is composed of the diaphragm 102 and the piezoelectric element 103. In the first embodiment, the rotor 101 is rotationally driven by three sets of vibrators. In FIG. 1, only one of the three sets is given a symbol in order to prevent the drawing from being complicated. Reference numeral 104 denotes a first holding member that holds the vibrator with respect to a ring member 107 described later. Reference numeral 105 denotes a buffer material that absorbs vibration of the piezoelectric element 103, and is formed of, for example, felt. Reference numeral 106 denotes a second holding member that pressurizes the vibrator to the rotor 101 via the buffer material 105. The second holding member 106 is disposed in an opening 104 b (FIG. 4) formed at the center of the first holding member 104. Reference numeral 107 denotes a ring member corresponding to the base of the present invention, which holds the first holding member 104, the second holding member 106, a pressure shaft 108, a leaf spring 109, and the like, which will be described later.

  Reference numeral 108 denotes a pressure shaft attached to the hole 107a of the ring member 107, and is held so as to be movable only in a direction perpendicular to the contact surface 101a. The buffer material 105 and the second holding member 106 are held by a leaf spring 109 described later. And pressurizing the vibrator onto the contact surface 101a of the rotor 101. Reference numeral 109 denotes a leaf spring, which fixes both ends to the ring member 107 with two screws 110 to generate pressure. The pressing shaft 108 and the leaf spring 109 correspond to a pressing unit.

  As described above, the above-described members are assembled and unitized as an ultrasonic motor. When incorporated in an actual lens barrel or the like, the rotor 101 is driven by being connected to a focus or zoom mechanism.

  Next, details of components of the ultrasonic motor will be described. FIG. 3 is an enlarged perspective view for explaining the coupling state of the diaphragm 102 and the first holding member 104 in FIGS. 1 and 2, and is a view seen from the rotor 101 side, that is, a view upside down. In the figure, two projections 102b are formed on the flat plate 102a at the center of the diaphragm 102. The lower end surface of the protrusion 102b, that is, the two surfaces that contact the contact surface 101a of the rotor 101 are formed as the same surface, and in order to improve the contact state with the contact surface 101a, it is uniform during the manufacturing by a polishing process or the like. Finished on the surface.

  On the other hand, the piezoelectric element 103 is pressure-bonded to the back side of the flat plate portion 102a with an adhesive or the like. The piezoelectric element 103 is formed by laminating and integrating a plurality of piezoelectric element films. A desired alternating voltage is applied via a flexible printed circuit board (not shown) bonded to the piezoelectric element 103 to excite the vibration plate 102 in two vibration modes. At this time, by setting the vibration phase of the two vibration modes to be a desired phase difference, elliptical vibration as indicated by an arrow in the figure is generated in the protrusion 102b. The elliptical vibration is generated by three vibrators as shown in FIGS. 1 and 2 and transmitted to the contact surface 101a of the rotor 101, whereby the rotor 101 can be driven to rotate. Note that details regarding the laminated structure and vibration mode of the piezoelectric element 103 are the same as those described in Japanese Patent Application Laid-Open No. 2004-30487, and thus detailed description thereof is omitted.

  Next, in the vicinity of both ends of the diaphragm 102, two joint portions 102 c formed at both ends of the first holding member 104 for joining with the one-step higher flat portion 104 a are formed. The diaphragm 102 is joined to the first holding member 104 by welding or adhesion at the joint 102c.

  Two arm portions 102d are formed between the two joint portions 102c and the flat plate portion 102a, and the vibrator is fixed to the first holding member 104 via the arm portions 102d. As shown in the figure, the arm portion 102d has a shape that is sufficiently thin with respect to the flat plate portion 102a and the joint portion 102c, and is configured to prevent the vibration generated in the flat plate portion 102a from being transmitted to the joint portion 102c. . In other words, the first holding member 104 plays a role of connecting so as not to inhibit the vibration generated in the flat plate portion 102a. An opening 104 b (FIG. 4) is formed in the portion of the first holding member 104 facing the piezoelectric element 103, and the applied pressure is transmitted by the second holding member 106 through the buffer material 105. Yes. Details will be described with reference to the cross-sectional view of FIG.

  FIGS. 4A and 4B are enlarged cross-sectional views showing a state in which each member is incorporated, and only one of the three vibrators is enlarged. Note that the remaining two locations have the same configuration and will not be described. FIG. 4A is a cross-sectional view in which a plane including a line connecting the centers of the two protruding portions 102b of the diaphragm 102 in FIG. 3 is a cut surface. FIG. 4B is a cross-sectional view orthogonal to FIG. 4A and passing through the center.

  In the figure, 201 is a center line that is equal in distance from the two protrusions 102 b of the diaphragm 102 and is orthogonal to the rotor 101. Reference numeral 202 denotes a center line that passes through the center of the protrusion 102 b and is orthogonal to the rotor 101.

  The lower end surface of the protrusion 102b is in contact with the contact surface 101a of the rotor 101 and is in a frictional contact state. The piezoelectric element 103 is bonded to the vibration plate 102, and is bonded to the first holding member 104 at two flat portions 104a at the bonding portions 102c at both ends. An opening 104b is formed near the center of the first holding member 104, and the cushioning material 105 and the second holding member 106 are disposed so as to enter the opening 104b. The shaft portion 104c of the first holding member 104 and the shaft portion 106b of the second holding member 106 are respectively fitted and positioned in the holes 107b and 107c of the ring member 107, and can be moved in the direction of the center line 201, respectively. It has a configuration. Therefore, a slight gap is formed between the first holding member 104 and the second holding member 106 as shown in the figure, and the first holding member 104 and the second holding member 106 are not in contact with each other.

  Near the upper center of the second holding member 106, a convex portion 106e formed by a part of a cylindrical surface obtained by pushing out a circle indicated by 203 in the depth direction of the drawing is provided. And the lower end plane part of the pressurization axis | shaft 108 is contacting this convex part 106e. Therefore, in FIG. 4A, the contact between the convex portion 104e and the pressing shaft 108 is a point contact, and the tilt is possible with the center of the circle 203 as the center of rotation. However, since the shaft portion 106b of the second holding member 106 is positioned by fitting into the hole portion 107c of the ring member 107, the shaft portion 106b can be slightly tilted within the range of the fitting backlash. In FIG. 4B, since the convex portion 106e is formed in a cylindrical surface, the contact between the convex portion 106e and the pressure shaft 108 is a line contact and cannot be inclined.

  Next, the pressing shaft 108 is fitted into a hole 107 a formed near the center of the ring member 107 and is held so as to be movable only in the direction of the center line 201. A leaf spring 109 is in contact with the convex portion on the upper side of the pressure shaft 108 in a state of being pressure-deformed. The both ends of the leaf spring 109 are fixed to the ring member 107 with screws 110. Then, the pressure applied by the deformation of the plate spring 109 is transmitted to the diaphragm 102 integrated with the piezoelectric element 103 via the pressure shaft 108, the second holding member 106, and the buffer material 105, and is transmitted to the rotor 101. It is possible to pressurize. The leaf spring 109 has a shape that follows an arc, and is formed of a thin plate material as long as possible so as to reduce the spring constant. By doing so, even when a component error occurs, it is possible to reduce variations in the applied pressure.

  In the first embodiment, the first holding member 104 for positioning and holding the diaphragm 102 and the second holding member 106 for holding pressure are separately provided, and each of them is only in a direction orthogonal to the rotor 101. Is configured to be movable. Therefore, it is possible to pressurize the vicinity of the center of the upper surface side of the vibration plate 102 via the piezoelectric element 103 and the buffer material 105 while holding the vibration plate 102 with the joint portions 102 c near both ends having little influence on vibration. Further, even if there is a difference in thickness between the piezoelectric element 103 and the buffer material 105, it can be absorbed by the advancing / retreating mechanism of the second holding member 106, and the mass productivity is high. Furthermore, even when a force that reduces the distance between the rotor 101 and the ring member 107 due to a drop or impact can be absorbed by the advance / retreat mechanism of the first holding member 104 and the second holding member 106. In addition, an excessive force is not applied to the diaphragm 102, and there is an effect of preventing destruction. Furthermore, since such a force can be directly received by the second holding member 106 via the buffer material 105, the vibration plate 102 and the piezoelectric element 103 are not destroyed.

  In the first embodiment, the first holding member 104 and the second holding member 106 are formed of plastic resin or the like. However, since the first holding member 104 is directly joined to the diaphragm 102, A material with greater damping against vibration is used.

  In general, a material with high rigidity such as metal has a small attenuation with respect to vibration, and a material with low rigidity such as rubber has a large attenuation with respect to vibration, so that the vibration can be stopped quickly. However, in recent years, various types of plastic resins have been developed as having a large damping against vibration while maintaining rigidity. On the other hand, in ultrasonic vibration, surrounding parts that hold the vibrator are affected by the vibration, and may generate abnormal noise in the audible range.

  However, in the first embodiment, by using a material having a large attenuation as described above for the first holding member 104, vibrations leaking from the diaphragm 102 can be absorbed in the first holding member 104. It becomes possible. Therefore, it is possible to prevent the first holding member 104 itself from becoming an abnormal sound source. In addition, since vibration is not transmitted to other members such as the connected ring member 107, it is possible to prevent the other members from becoming abnormal noise sources.

  Since the second holding member 106 is in contact with the piezoelectric element 103 via the shock absorbing material 105 that absorbs a large amount of attenuation, most vibrations are attenuated in the shock absorbing material 105, and the second holding member 106 There is little vibration transmitted to the holding member 106. Therefore, since the second holding member 106 is configured to receive a pressure force directly, a material having higher strength is used.

  With the configuration as described above, a complicated adjustment mechanism and a positioning mechanism are not required as in the conventional example, and the vibrator can be stably pressed against the driven body with a low cost and a simple configuration.

  FIG. 5 is a cross-sectional view corresponding to FIG. 4A and shows a state where the rotor 101 is tilted. In the figure, the protrusion 102b of the diaphragm 102 follows the contact surface 101a of the rotor 101, and can maintain a frictional contact state.

  This is because the vibrator composed of the vibration plate 102 and the piezoelectric element 103 is inclined in accordance with the inclination of the rotor 101, and the first holding member 104 connected thereto is inclined. Further, the second holding member 106 follows the inclination of the vibrator with the cylindrical center of the convex portion 106 e formed of a cylindrical surface as the rotation center, and is inclined via the buffer material 105.

  Therefore, it is possible to maintain a stable frictional contact state at the two protruding portions 102b even when an inclination occurs due to a dimensional error or an assembly error of each member, or even when an inclination occurs due to vibration or disturbance during driving. It becomes. That is, it is possible to improve the equalization property of the vibrator with respect to the rotor 101. In the description of FIG. 5, the amount of tilt is exaggerated for easy understanding of the tilted state. The actual amount of inclination is only the amount of looseness that fits the first holding member 104 and the second holding member 106 with respect to the ring member 107.

  As described above, in the first embodiment, since the first holding member 104 and the second holding member 106 that hold the diaphragm 102 are separately provided, the vibrator can be a driven body with a simple configuration. On the other hand, it becomes possible to pressurize stably.

  In the first embodiment, the large area in the vicinity of the center of the piezoelectric element 103 is pressed through the buffer material 105. However, the second holding member 106 is provided with a protrusion only in a portion corresponding to the vibration node. A configuration may be adopted in which only the vicinity of the node is pressurized. Since such a method does not further inhibit the vibration of the piezoelectric element 103, an effect of suppressing power consumption is expected. Further, the first holding member 104 and the second holding member 106 are configured to use a plastic resin in consideration of strength and vibration suppression, respectively. However, when using a material such as a metal with high rigidity for these holding members, the shape of the member is optimized to optimize the thickness, length, and cross-sectional shape, and the resonance point is set near the drive frequency of the vibrator. By not having it, generation of abnormal noise due to vibration can be reduced.

  Moreover, although the said Example 1 demonstrated the rotation drive as an example, it is not limited to this, For example, it can apply also in a linear drive.

  The second embodiment is a modification of the first embodiment, and is an example in which the shaft portion 106b of the second holding member 106 fitted to the hole 107c of the ring member 107 in the first embodiment is eliminated.

  6A and 6B are enlarged cross-sectional views showing a state in which each member is incorporated, and correspond to FIGS. 4A and 4B, respectively. The same members as those in the first embodiment are denoted by the same symbols, and detailed description thereof is omitted. In the figure, the second holding member 301 is disposed so as to be fitted into an opening 104b provided near the center of the first holding member 104, and is movable only in the direction of the center line 201 and the center line 202. It has a configuration. Other configurations are the same as those in the first embodiment, and can be tilted in accordance with the tilt of the rotor 101.

  The second holding member 301 has a simpler configuration with no shaft portion compared to the first embodiment. Therefore, since the mass productivity of manufacturing is improved, it is possible to select not only a plastic resin but also a wide range of materials such as metals and ceramics.

  Further, as shown in FIG. 5, in the first embodiment, the first holding member 104 and the second holding member 106 are separately inclined through the vibrator when inclined. However, in Example 2, since the second holding member 301 is fitted to the first holding member 104, the second holding member 301 follows the inclination of the first holding member 104. Since it can incline, the 1st holding member 104 and the 2nd holding member 301 can incline integrally.

101 rotor (driven body)
DESCRIPTION OF SYMBOLS 102 Diaphragm 103 Piezoelectric element 104 1st holding member 105 Buffer material 106 2nd holding member 107 Ring member 108 Pressurizing shaft 109 Leaf spring 301 2nd holding member

Claims (11)

A vibrator that generates vibration;
A first member holding the vibrator;
Pressurizing means;
A second member to which the force of the pressing means is transmitted;
Have,
Before SL is the first member, a motor, wherein the damping us go size to vibration of the vibrator than the second member.   The motor according to claim 1, wherein the second member is formed of a member having a higher strength than the first member. 3. The motor according to claim 1, wherein the first member is made of a material that is more damped against vibration than the second member. 4. A buffer member disposed between the vibrator and the second holding member;
The force by the pressurizing means is transmitted to the vibrator via the second member and the buffer member,
The motor according to claim 1, wherein the buffer member absorbs vibration of the vibrator. Said second member, a motor according to any one of claims 1 to 4, characterized in that in contact with the pressurizing means. The motor according to claim 5 , wherein the second member has a convex portion, and the convex portion is in contact with the pressurizing unit. The vibrator motor according to any one of claims 1 to 6, characterized in that to generate the elliptical motion. A vibrator that generates vibration;
A first member holding the vibrator;
A second member for transmitting a pressing force to the vibrator,
The motor according to claim 1, wherein the first member is more damped to vibration of the vibrator than the second member. The motor according to claim 8, wherein the first member is not disposed between the vibrator and the second member. The motor according to claim 8, wherein the first member is not in contact with the second member. A lens barrel having a lens driven by a motor according to any one of claims 1 to 10.