JP2012100513A - Actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high output and highly reliable actuator.SOLUTION: The actuator includes: a vibrator 6 which is made into a cantilever shape where one end is set to be a fixed end and the other end is a free end, and in which a friction driving portion 4 is arranged on the other end side; and a movable member 3 which has a hole 3a into which the friction driving portion 4 of the vibrator 6 is inserted in a state where play is formed to an inner face and is rotatably held at a periphery of the vibrator 6. When the vibrator 6 is vibrated, the friction driving portion 4 abuts on an inner face of the hole 3a of the movable member 3, and is driven to draw a track where a place abutted in a planar and perspective view from the other end side is overlapped with a circumference with one end as a center, and the driving portion rotates the movable member 3 at the periphery of the vibrator 6.

Description

  The present invention relates to an actuator that converts a vibration generated using a piezoelectric element or the like into a linear motion or a rotational motion and drives it.

  As various devices become more sophisticated, smaller and lighter, there is a growing demand for actuators that are small and have high output. On the other hand, piezoelectric actuators and ultrasonic motors have been devised that obtain large displacements or high torque by repeatedly using minute displacements such as piezoelectric elements. For example, in Patent Document 1, a progressive vibration wave is generated in the circumferential direction of a circular vibration body, a contact body that contacts the vibration body is provided, and the vibration body and the contact body have a relationship between a male screw and a female screw. Actuators have been proposed that move in a straight line. Such an actuator is used as an actuator for driving a lens by an autofocus mechanism of a camera.

JP-A-62-225182

  Piezoelectric actuators and ultrasonic motors generate more energy per volume or weight than electromagnetic motors. Furthermore, there is an advantage that it is excellent in high-speed response and position retention and is not affected by magnetism. However, in the structure in which the piezoelectric ceramics shown in Patent Document 1 are bonded to the vibration ring, since the stress limit of the piezoelectric ceramics is low, it is difficult to generate large vibration and amplitude, and it is difficult to obtain a large output. Therefore, the application application of such a piezoelectric actuator is limited to small devices such as watches, cameras, and printers.

  The present invention has been made to solve the above-described problems, and an object thereof is to obtain an actuator capable of outputting a high torque. Another object is to obtain a highly reliable actuator.

  An actuator according to an example of an embodiment of the present invention has a cantilever shape in which one end is a fixed end and the other end is a free end, and a friction drive unit is provided on the other end side. A vibrating body, and a movable member that has a hole portion that is inserted in a state in which the friction drive unit of the vibrating body provides play with respect to the inner surface and is rotatably held around the vibrating body. . When the vibrating body is vibrated, the friction drive unit contacts the inner surface of the hole portion of the movable member, and a portion that contacts when viewed through the other end side in plan view is the one end portion. Is driven so as to draw a trajectory that overlaps with the circumference centered on, thereby rotating the movable member around the vibrating body.

  According to said structure, the friction drive part of a vibrating body will oscillate, repeating contact | abutting, changing a position continuously with respect to the inner surface of the hole of a movable member. As a result, the movable member rotates with the driving force applied by the frictional drive unit of the vibrating body.

According to the actuator according to an example of the embodiment of the present invention, it is possible to provide an actuator that gives a large torque driving force with little transmission loss of the driving force from the vibrating body to the movable member. Moreover, since it has high reliability, it can be a long-life actuator. Thereby, for example, an actuator that can be applied to an application that requires a high driving force and high reliability, such as a waist or a joint of a robot, can be provided.

It is a figure which shows the actuator which concerns on an example of embodiment of this invention, (a) is a side view, (b) is sectional drawing. It is a figure which shows the structure of the vibrator | oscillator of the actuator which concerns on an example of embodiment of this invention, (a) is a figure which shows an electrode area | region when seeing a vibrator | oscillator from a central-axis direction, (b) is (a) It is an arrow directional cross-sectional view of the AA 'line which showed the electrode part of) typically. It is a figure which shows the waveform (voltage-time characteristic) of the voltage applied to the vibrator | oscillator shown in FIG. FIG. 4 is a diagram illustrating a state of a vibrating body at a time T2 in FIG. 3 in an actuator according to an example of an embodiment of the present invention. It is a schematic diagram explaining the movement of a friction drive part using the arrow BB 'sectional drawing of the actuator shown in FIG. 4, When (a) is not vibrating, (b) is (1)-. The state when vibrating in the order of (6) is shown. It is the simulation result which calculated | required the natural vibration frequency of the actuator which concerns on an example of embodiment of this invention, and shows the natural vibration of a primary mode. It is the simulation result which calculated | required the natural vibration frequency of the actuator which concerns on an example of embodiment of this invention, and shows the natural vibration of a high-order mode. It is a schematic diagram which shows the assembly method of the actuator which concerns on an example of embodiment of this invention. It is a schematic diagram which shows the assembly method of the actuator which concerns on an example of embodiment of this invention, and shows the assembly method of a cap. It is sectional drawing which shows the actuator which concerns on another example of embodiment of this invention. It is sectional drawing which shows the actuator which concerns on another example of embodiment of this invention.

  Hereinafter, examples of embodiments of the present invention will be described in detail with reference to the drawings.

  However, in each drawing referred to below, for convenience of explanation, among the constituent members of one embodiment of the present invention, only the main members necessary for explaining the present invention may be shown in a simplified manner. Therefore, the actuator according to an example of the embodiment of the present invention may include any constituent member that is not shown in each drawing referred to in this specification. Moreover, the dimension of the member in each figure is typical, and does not faithfully represent the dimension of the actual component member, the dimension ratio of each member, or the like.

  1A and 1B are views showing an actuator according to an example of an embodiment of the present invention, where FIG. 1A is a side view and FIG. 1B is a cross-sectional view thereof.

  The actuator 10 according to the present embodiment includes a vibrating body 6 and a movable member 3 that is rotatably held around the vibrating body 6.

In the present embodiment, the vibrating body 6 is formed by stacking the elastic body 1a, the vibrator 2, the elastic body 1b, and the friction drive unit 4 in this order. Alternatively, the vibrator 2, the elastic body 1b, and the friction drive unit 4 are stacked in this order. At the center of each member, a through hole for passing a bolt 5 as a fastening member is provided, and the bolt 5 is fastened to a base (not shown) and integrated. Specifically, it is in the form of a bolted Langevin type vibrator. Therefore, the vibrating body has a cantilever shape in which one end portion tightened with the bolt 5 is a fixed end and the other end portion provided with the friction drive unit 4 is a free end.

  The movable member 3 has a cylindrical shape, and the inner wall of this cylinder constitutes the inner surface of the hole 3a and is sized to accommodate the vibrating body 6. Although details will be described later, the friction drive unit 4 of the vibrating body 6 and the inner surface of the hole 3a are provided with a certain play (clearance), and when the vibrating body 6 is vibrated, the friction drive unit 4 The side portion is in contact with the inner surface of the hole 3 a of the movable member 3 and is configured to apply a driving force for rotating around the vibrating body 6.

  The movable member 3 is rotatably held around the vibrating body 6. In the present embodiment, a convex portion and a concave portion having a spiral shape are formed on the outer surface of the vibrating body 6 and the inner surface of the hole portion 3a of the movable member 3 so as to be fitted to each other. Specifically, the screw groove 14 is formed on the side surface of the elastic body 1a and the screw groove 16 is formed on the side surface of the elastic body 1b as a spiral shape (first spiral shape) on the vibrating body 6 side. In addition, screw grooves 15 and 17 are formed on the inner surface of the hole 3a as a spiral shape (second spiral shape) on the movable member 3 side. And these 1st and 2nd spiral shapes are mutually fitted form. According to this configuration, the movement of rotating the movable member 3 around the vibrating body 6 is converted into the linear movement of the vibrating body 6 in the axial direction. By transmitting the movement of the movable member 3 to a driven body (not shown), the driven body can be driven. Further, when the vibration of the vibrating body 6 is stopped and the rotation of the movable member 3 is stopped, for example, even if a force is applied in the axial direction due to the weight of the driven body, the spiral shapes are locked. Since the rotation is inhibited, the actuator 10 is stationary with respect to the axial direction, and the position is maintained.

  When the movable member 3 is driven in the axial direction of the vibrating body 6 by the above-described mechanism, a cap 7 that protrudes in the distal direction can be provided at the distal end of the movable member 3 as shown in FIG. . When the tip of the cap 7 protrudes from a convex surface or a hemispherical surface, the movable member 3 rotates in the axial direction while rotating around the axis of the vibrating body 6 and comes into contact with the driven body. In addition, the contact area with the driven body is reduced and the friction is reduced. The cap 7 can also be held rotatably with respect to the movable member 3. In this case, since the cap 7 idles with respect to the movable member 3 and relative rotation with the driven body is suppressed, wear of the tip portion of the cap 7 where stress is most concentrated can be suppressed.

  As the elastic bodies 1a and 1b and the fastening member (bolt) 5, a known elastic body can be used, but generally a metal is used. The vibrator 2 is an electro-mechanical energy conversion element, and is configured using, for example, a multilayer piezoelectric element. Details of the configuration of the vibrator 2 will be described later.

  Since the movable member 3 is easy to process, a metal is used. Here, since the friction drive unit 4 abuts against the inner surface of the hole 3a of the movable member 3 in order to apply a driving force, the portion abutting on the friction drive unit 4 has excellent wear resistance such as ceramics. It may be formed of different materials. Or you may perform the coating excellent in abrasion resistance. Moreover, since the side part also contacts the movable member 3 and gives a driving force, the friction drive part 4 is desirably made of a material having excellent wear resistance such as ceramics. In addition, it is preferable to select a material having a large mutual friction coefficient at a portion where the friction drive unit 4 and the movable member 3 abut, because energy loss during power transmission is reduced.

  Next, the structure of the vibrator according to this embodiment will be described. 2A is a diagram showing an electrode region when the vibrator is viewed from the central axis direction, and FIG. 2B is an arrow AA ′ line schematically showing the electrode portion of FIG. FIG.

The vibrator 2 is an electro-mechanical energy conversion element. For example, a piezoelectric element (piezo element) made of ceramics such as PZT (lead zirconate titanate) can be used. The piezoelectric element is polarized in the thickness direction (vertical direction in FIG. 2B), and the vibrator 2 is provided with a plurality of electrodes divided in the rotational direction of the movable member 3 (around the axial direction). Yes. In the example shown in FIG. 2A, it is divided into four regions I, II, III and IV as indicated by dotted lines, and voltages having different phases can be independently applied to these regions. It has become.

  The structure of these electrode regions is shown in the sectional view of FIG. The vibrator 2 is a stacked piezoelectric element in which a plurality of electrode layers are formed in each of the electrode regions I to IV divided inside. In the example of the electrode region II, the positive electrode-side external electrode 201 and the negative electrode-side external electrode 203 are respectively provided on the side surfaces of the region. In addition, a positive electrode and a negative electrode show the difference in polarity, and do not show the positive / negative of an applied voltage. A plurality of internal electrodes 205 are provided so that the external electrodes 201 and 203 are common electrodes, and are alternately stacked with the piezoelectric layers interposed therebetween. The external electrodes 201 and 203 are connected to a lead-out wiring 202 on the positive electrode side and a lead-out wiring 204 on the negative electrode side, respectively, and independently apply voltages having different phases to each electrode region divided from a power supply device (not shown). Be able to. By using such a laminated piezoelectric element, a large displacement can be obtained under a high pressure, so that brittle fracture of the piezoelectric element can be suppressed and a high torque actuator can be obtained. Note that the laminated piezoelectric element is not bonded to the elastic bodies 1a and 1b but is fixed by a bolt, so that functional deterioration due to destruction of the bonded portion hardly occurs.

Such a laminated piezoelectric element is provided by the following manufacturing method, for example. An internal electrode is formed on a Pb (Zr—Ti) O ₃ ceramic green sheet by printing or vapor-depositing a conductive paste made of Ag, Pd, Pt, Ni, Au, or an alloy powder containing at least one of these. These sheets are alternately stacked and stacked, and the sheet is cut or punched into the shape of the vibrator 2 (in the present embodiment, a ring shape). After debinding and firing, a conductive paste made of Ag, Pd, Pt, Ni, Au, or an alloy powder containing at least one of these is applied to the end face, and further sintered to produce an external electrode.

  The external electrode on the outer wall and the external electrode on the inner wall of the vibrator 2 having a ring shape are connected to the positive electrode and the negative electrode, respectively, a predetermined DC voltage is applied between the positive electrode and the negative electrode, an electric field is applied, and the treatment is performed for a predetermined time. By doing so, the piezoelectric layer can be polarized to obtain the vibrator 2 of the present embodiment.

  One of the positive electrode and the negative electrode may be a common electrode in each electrode region, and the other may be an individual electrode in each electrode region. In this case, since the electrode formation region is shared by each electrode region, it is suitable for miniaturization.

  Next, the driving principle of the actuator according to an example of the embodiment of the present invention will be described.

  FIG. 3 shows a waveform (voltage-time characteristic) of a voltage applied to the vibrator 2, and FIG. 4 is a schematic diagram showing a state of the vibrating body 6 at time T2 in FIG.

  In FIG. 3, (a) to (d) are sine waves having different phases, and in the relationship V = Asin (ωT−θ) (A: amplitude, ω: angular frequency, −θ: initial phase), A is (A) to (d) are constant, θ is (0) when (a) is 0 °, (b) is 90 °, (c) is 180 °, (d) is 270 °, and the phase is shifted every 90 °. Yes.

Assuming that the voltage waveforms applied to the positive electrodes of the electrode regions I to IV shown in FIG. 2 are (a) to (d), respectively, the electrode region II of the vibrator 2 (right side of FIG. 4) at the moment T = T2. ) And the electrode region IV of the vibrator 2 (left side in FIG. 4) is displaced so that the thickness is decreased.

  As a result, at the moment of T = T2, the vibrator is in a state where the vibrating body 6 is bent from the electrode region II toward the electrode region IV. Here, when a sine wave voltage synchronized so that V = Asin (ωT−θ) is applied to each electrode region, electrode region I → electrode region II → electrode region III → electrode region IV → electrode region I Repeat the compression motion in the order of. Since the lower end portion of the vibrating body 6 is fixed by the bolt 5, the bending motion of the vibrating body 6 is a motion that causes the friction drive unit 4 to swing. Although FIGS. 2 to 4 are described using an example in which the electrode region of the multilayer piezoelectric element is divided into four, the number of divisions may be at least three or more. Further, the number of divisions may be larger than four, and thereby the swing motion can be further smoothed.

  Next, the principle of applying a driving force for rotating the friction drive unit 4 to the movable member 3 by the bending motion of the vibrating body 6 will be described. Here, the case where the number of divisions of the electrode region is further increased to be divided into six will be described.

  FIG. 5 is a schematic diagram for explaining the movement of the friction drive unit using the cross-sectional view taken along the line B-B ′ of the actuator shown in FIG. 4, and FIG. Further, (b) shows a state in which a sinusoidal voltage having a phase difference of 60 ° is applied to the electrode region divided into six and is vibrated in the order of (1) to (6).

  As shown in FIG. 5A, a certain clearance is provided between the friction drive unit 4 of the vibrating body 6 and the inner surface of the hole 3 a of the movable member 3. Here, as shown in FIG. 5B (1), when the vibrating body 6 is vibrated so as to bend in one direction of the divided electrode regions, the side surface of the friction drive unit 4 is moved to the movable member 3. It contacts the inner surface of the hole 3a. After that, by bending and vibrating the adjacent electrode regions that are sequentially divided, as shown in (2) to (6), the vibration body 6 itself does not rotate, and the side surface of the friction drive unit 4 is moved to the movable member 3. The position changes one after another and contacts the inner surface of the hole 3a.

  The vibrating body 6 tries to return to the position shown in FIG. 5A by the elastic restoring force, but by increasing the number of divisions and the frequency of the sine wave voltage applied to the electrode region, the friction drive unit 4 of the vibrating body 6 can be obtained. The portion where the contact is made draws a trajectory that overlaps the circumference centered on the fixed end (one end) of the vibrating body 6, and the friction drive unit 4 continuously changes its position to the inner surface of the hole 3 a of the movable member 3. While swinging, the head swings. As a result, the movable member 3 is given a driving force by the friction drive unit 4 of the vibrating body 6 and rotates around the vibrating body 6.

  Conventional ultrasonic motors generate a traveling wave that causes elliptical vibration to the stator, thereby applying a rotational driving force to the rotor that is in pressure contact with the surface of the stator. Since the actuator applies a rotational driving force to the inner surface of the hole 3a of the movable member 3 by the swinging motion of the friction drive unit 4, it is superior in terms of energy efficiency compared to a conventional ultrasonic motor. .

  In the above-described example, the description has been given using an example in which the electrode region of the multilayer piezoelectric element is divided into four and six. However, a rotational driving force is applied to the inner surface of the hole 3a of the movable member 3. In order to cause the oscillating motion to be caused to the vibrating body 6, the electrode region of the laminated piezoelectric element only needs to be divided into at least three electrode regions.

Further, in the above-described example, as the phase of the AC voltage applied to the divided electrode region of the vibrator 2, an AC voltage having a phase shifted by 90 ° is applied when divided into four, and the phase is changed when divided into six. An alternating voltage shifted by 60 ° is applied. By applying an alternating voltage to the electrode regions divided in this way so that the electrode regions facing each other across the center have a phase difference of 180 °, the vibrators are mutually opposed at the positions facing each other across the center. It is possible to move in the opposite direction, and the vibrating body 6 can be displaced further.

  In addition, when the movable member 3 is to be rotated in the reverse direction, a sine wave voltage having a predetermined phase difference may be applied to the divided electrode regions in the reverse direction. For example, in the case of FIG. 5B, the vibration is performed in the order of (6) → (1).

  Next, an example of a method for designing the actuator according to the present embodiment will be described.

  First, by using the resonance phenomenon by matching the natural vibration frequency of the vibrating body 6 with the frequency ω of the voltage V = Asin (ωT−θ) shown in FIG. 3, the vibrating body can obtain a large displacement. It is desirable to do. The frequency of the natural vibration is determined by the structure and the material of the vibrator 2, the elastic body 1a, the elastic body 1b, the bolt 5, and the friction drive unit 4 constituting the vibrating body.

  As an example, FIG. 6A shows the result of obtaining the natural vibration frequency using a finite element method simulation tool in the vibrating body having the structure shown in FIG. Here, it is assumed that the vibrator 2 is PZT, the friction drive unit 4 is alumina, and the elastic bodies 1a and 1b and the bolt are steel, and the dimensions thereof are constituted by the vibrator 2 and the elastic bodies 1a and 1b. It was assumed that the diameter of the cylindrical shape was 40 mm and the height was 62.5 mm, the friction drive unit 4 had a diameter of 45 mm and a height of 5 mm, and the bolt 5 had a diameter of 14 mm. When the simulation was performed by giving the above values, the natural vibration frequency ω was 4.768 kHz.

  FIG. 6b shows the natural vibration in the higher order mode in the same model, and the natural vibration frequency ω = 14.96 kHz was obtained. As described above, the natural vibration has a plurality of vibration modes. As to which mode is to be used, an appropriate one may be selected in consideration of the obtained displacement amount and the given frequency.

Next, the clearance between the friction drive unit 4 and the inner surface of the hole 3a of the movable member 3 for properly contacting the movable member 3 and the friction drive unit 4 is quantified. The displacement amount ΔZ of the vibrator 2 is determined by ΔZ / Z ₀ = d ₃₃ · V. (Z ₀ : element thickness, d ₃₃ : piezoelectric constant, V: applied voltage) d ₃₃ is determined by the material. Since this value can take a wide range of d ₃₃ = 50 to 800 × 10 ⁻¹² m / V, a material may be selected so that a necessary displacement amount can be obtained.

  Use of a laminated piezoelectric element is desirable because a sufficiently large displacement can be obtained. As a result of experiments conducted by the present inventor, the thickness of the laminated piezoelectric element having a total thickness of 10 mm, in which about 130 layers are laminated, is displaced by about 9 μm when 100 V is applied. Based on this experimental result, the displacement shown in FIG. 1 is used to calculate the displacement amount of the frictional drive unit 4 due to the swing motion of the vibrating body 6 by the finite element method simulation in addition to the calculation of the piezoelectric material constant. It was found that a value of 1 mm was obtained. A displacement amount of 0.1 mm or more is obtained in both the first-order mode shown in FIG. 6a and the higher-order mode shown in FIG. 6b. Thus, the design accuracy of the fitting between the friction drive unit 4 and the movable member 3 (for example, the inner diameter tolerance of the hole 3a of the movable member 3 is +0.05 mm, and the outer diameter tolerance of the friction drive unit 4 is -0.05 mm). On the other hand, it was found that a sufficiently large displacement amount can be obtained and the movable member 3 can be driven by the friction drive unit 4.

  In addition, when providing the spiral shape which converts a rotational motion into a linear motion in the vibrating body 6 and the movable member 3, as shown to the broken line part D and E of FIG. It is good to set it as the dimension which a fitting state is not cancelled | released.

  Further, in order to estimate the generated force in the actuator designed as described above, the torque when using the vibration in the first mode was calculated, and a value of 2.5 N · m was obtained as the average torque. This is a high torque value of 100 times or more compared with the electromagnetic motor of the same size, and the superiority of this embodiment was confirmed.

  Next, a method for assembling the actuator according to the present embodiment will be described. FIG. 7 is a schematic diagram showing an actuator assembly method according to the present embodiment, and FIG. 8 shows an example of a cap assembly method.

  First, the vibrator 2 is disposed between the elastic bodies 1a and 1b and stacked. The movable member 3 is assembled so as to be inserted from above or below. At this time, a conducting wire (not shown) for energizing the vibrator 2 can be passed through a hole or the like provided in the side wall or inside of the elastic body 1a. Wiring may be performed by sandwiching a flexible substrate (not shown) between the elastic bodies 1 a and 1 b and the vibrator 2. After the friction drive unit 4 is placed on the elastic body 1b, the elastic bodies 1a and 1b, the vibrator 2 and the friction drive unit 4 are clamped with a predetermined gripping force by bolts 5 to form the vibration body 6. Since the inner diameter of the spiral thread formed on the inner wall of the movable member 3 is smaller than the diameter of the friction drive unit 4, it is desirable to follow the assembly order described above. Further, it is desirable that a thread for screwing the bolt 5 is provided in advance on an object on which the vibrating body 6 is provided.

  The cap 7 is made of a material such as ceramic having high wear resistance and high strength. In order to hold the cap 7 rotatably with respect to the movable member 3, as shown in FIG. 8, a protrusion is provided on the outer periphery of the cap 7, and the protrusion is formed in a groove formed in the inner wall of the movable member 3 in advance. It is recommended that you fit in.

  The present invention is not limited to the above-described embodiment, and various changes and improvements can be made without departing from the scope of the present invention.

  For example, in the above description, an example in which a laminated piezoelectric element is used as the vibrator 2 has been described. However, the present invention is not limited to this, and a single layer of a plurality of vibrators may be used. In addition, although the example using PZT has been described as the material of the vibrator 2, a ferroelectric single crystal or a polymer material having piezoelectricity can also be used.

  Further, the manufacturing method for obtaining the vibrator 2 has been described by the method of firing the ceramic green sheet, but is not limited thereto, and a thin film method such as a sputtering method may be used.

Further, although an example in which a sinusoidal AC voltage is applied to the divided electrode regions has been described, the present invention is not limited to this, and a triangular wave, a sawtooth wave, a pulse wave, or the like may be used. The modification will be specifically described with reference to FIG.

  FIG. 9 is a sectional view showing an actuator 20 according to another example of the embodiment of the present invention. In this embodiment, the elastic body 1a is omitted, the length of the movable member 13 is short, and the structure is simplified as compared with the embodiment shown in FIG. With such a configuration, the actuator can be further reduced in size.

FIG. 10 is a cross-sectional view showing an actuator 30 according to still another example of the embodiment of the present invention. In this embodiment, as compared with the embodiment shown in FIG. 1, a spiral shape that is screwed together is not provided between the vibrating body and the movable member 23. Therefore, the bending vibration of the vibrating bodies (elastic bodies 11a and 11b, vibrator 2 and bolt 5) is converted into a rotational motion in which the movable member 23 rotates around the axis of the vibrating body, and the rotation provided on the movable member 23. It can be taken out through the shaft portion 21 as a rotational motion. The ball bearing 19 is provided between the vibrating body and the movable member 23, and has an effect of smoothly rotating the movable member 23. The nut 9 is screwed into an end portion of the bolt 5 and becomes a fixed end of the vibrating body.

  Here, when convex portions 18a and 18b are provided so as to surround the inner circumference lower side of the hole 23a of the movable member 23 and the lower outer circumference of the vibrating body, respectively, and the movable member 23 is inserted into the vibrating body. The convex portion 18a on the movable member 23 side may be locked so as to be below the convex portion 18b on the vibrating body side. By providing such convex portions 18a and 18b that are locked with each other, when the movable member 23 is rotated by the friction drive unit 4, the movable member 23 is prevented from being detached from the vibrating body and stabilized. Rotation can be obtained.

DESCRIPTION OF SYMBOLS 1a, 1b Elastic body 2 Oscillator 3, 13, 23 Movable member 3a, 13a, 23a Hole part 4 Friction drive part 5 Bolt (fastening member)
6 Vibrating body 7 Cap 9 Nut 10, 20, 30 Actuator 11a, 11b, Elastic body 14, 16 Thread groove (first spiral shape)
15, 17 Thread groove (second spiral shape)
18a, 18b Convex part 19 Ball bearing 21 Rotating shaft part 201, 203 External electrode 202, 204 Lead wire 205 Internal electrode I, II, III, IV Electrode region

Claims (5)

One end portion is a fixed end and the other end portion is a cantilever beam having a free end, and a vibration body provided with a friction drive unit on the other end side;
An actuator having a hole that is inserted in a state in which the friction drive portion of the vibrating body provides play with respect to the inner surface, and a movable member that is rotatably held around the vibrating body; When the vibrating body is vibrated, the friction drive unit contacts the inner surface of the hole of the movable member, and the contacted portion when viewed in plan from the other end side is the one end portion. An actuator that is driven so as to draw a trajectory that overlaps with a circumference centered on, and rotates the movable member around the vibrating body. A first spiral-shaped convex portion or concave portion is formed on the surface of the vibrating body, and a first spiral-shaped convex portion or concave portion can be fitted to the inner surface of the hole of the movable member. 2 spiral convex portions or concave portions are formed,
In the vibrating body and the movable member, the first and second spiral convex portions or concave portions are fitted to each other, and the movement of rotating the movable member around the vibrating body vibrates the movable member. The actuator according to claim 1, which is converted into a linear motion that moves in the axial direction of the body. The vibrator is
A vibrator including an electro-mechanical energy conversion element;
An elastic body in contact with the vibrator;
The friction drive unit in contact with the elastic body;
The actuator according to claim 1, further comprising a fastening member that integrally tightens the vibrator, the elastic body, and the friction drive unit.   The vibrator is a single-layer type composed of one piezoelectric element or a laminated type in which a plurality of piezoelectric elements are laminated, and has an electrode divided into at least three in the rotation direction of the movable member. The actuator according to claim 1, wherein alternating voltages having different phases are applied to the electrodes.   The actuator according to any one of claims 1 to 4, wherein a cap having a convex surface or a hemispherical surface protruding toward a distal end is provided at a distal end of the movable member.