JP2009050041A - Friction drive actuator, and hard disc device using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the responsiveness, in an ultrasonic motor which is used for the drive, etc. of the magnetic recording head of an HDD. <P>SOLUTION: In the ultrasonic motor 1, the vibration of a vibrator 2 is transmitted to a rotor 3 that contacts it by friction and the rotor 3 rotates by containing the vibrator 2 which performs in-plane vibration in the rotor 3, the rotor 3 is constituted in combination of first and second members 31 and 32 forming a pair with a top and a bottom which have rigidity and are made in the shape of bottomed cylinders, and the vibrator 2 is pinched and retained between these bottom plates 31a and 32a by the snapping force generated by a coil spring 4, and also conical tapered faces 31c and 32c are formed on the bottom plates 31a and 32a. Accordingly, it can improve the responsiveness by dispensing with the bearing of a rotor 3, and also can stabilize the driving performance by stabilizing more the frictional force between the vibrator (stator) 2 and the rotor 3. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a friction drive actuator called an ultrasonic actuator, which is suitably used for driving a magnetic recording head of a hard disk device (hereinafter referred to as HDD), and the hard disk device.

  The ultrasonic actuator for driving the magnetic recording head of the HDD is required to have high precision positioning and high speed response. Therefore, Patent Documents 1 and 2 show typical prior arts that can be applied to such applications. FIG. 5 is a cross-sectional view of an ultrasonic actuator according to the prior art of Patent Document 1. This ultrasonic actuator is a typical example of a general traveling wave type rotary actuator, and ultrasonic vibrations traveling in the circumferential direction of a disk generated by a piezoelectric element 102 attached to a disk-shaped vibrating body 101 are generated. The mobile body 104 is rotated by being propagated to the mobile body 104 (rotor) via the liner 103.

  However, in this prior art, the moving body 104 is positioned by a bearing 105 formed of a ball bearing. Accordingly, since the ball bearing has a slight backlash between the ball and the inner ring and the outer ring, the position change of the rotor (moving body 104) and unnecessary resonance occur, and the accuracy is increased. In some cases, there is a limit to improving the recording density. In addition, there is a problem that the bearing load due to the inertial mass of the ball bearing, the frictional resistance of the bearing, and the viscous resistance of the bearing lubricant becomes a restriction on the improvement of the response. Specifically, the drive response as an ultrasonic actuator for driving the magnetic recording head of the HDD is determined by the resonance frequency of the arm portion, the resonance frequency of the bearing portion, the resonance frequency of the suspension attached to the tip, and the like. As the HDD size is reduced, the resonance frequency of the arm portion and the suspension can be designed to be relatively high. For this reason, the backlash, inertial mass, and bearing load at the bearing portion are the constraints on the response. Yes.

  Similarly, in the prior art of Patent Document 2 shown in FIG. 6, the bearings 111 and 112 made of ball bearings are used.

Therefore, Patent Document 3 is given as another conventional technique that can solve such a problem. In the prior art, as shown in FIG. 7, a vibrating body (stator) 131 that vibrates in a plane is sandwiched between a pair of upper and lower ring-shaped rotors 132 and 133, and the contact surfaces 132a and 133a are tapered. The vibrator 131 is pressed in the radial direction by sandwiching the top and bottom. With such a configuration, the rotors 132 and 133 are pressed and contacted with the fixed vibrating body 131, so that there is no bearing play, and therefore there is no blurring at the center of rotation, and high responsiveness is obtained.
JP-A-6-78570 JP 7-178370 A Japanese Patent Laid-Open No. 6-276663

  In the above-described Patent Document 3, two upper and lower rotors 132 and 133 are used as rotors, and bolts 134 and nuts 135 are used for coupling them. Accordingly, the tightening (friction) force varies between the plate-like, low-rigid rotors 132 and 133 where they are joined, and the parts that are not so. As a result, the driving of the rotors 132 and 133 has uneven speed and torque. .

  In this regard, in another embodiment shown in FIG. 8, by providing a thin elastic hinge portion 137 between the frame portion of the rotors 132 and 133 and the portion sandwiching the vibrating body 131, the elasticity of the rotors 132 and 133 is improved. The structure which utilizes and presses is shown. However, with this configuration, there is a problem that the spring constant changes greatly due to a slight difference in wall thickness, resulting in a difference in driving torque.

  An object of the present invention is to support a rotor without bearings by enclosing a vibrating body (stator) that performs in-plane vibration in a rotor, and transmitting the vibration of the vibrating body to a rotor in frictional contact and rotating the rotor. Another object of the present invention is to provide a friction drive actuator capable of stabilizing the friction force between the vibrating body and the rotor, and a hard disk device using the same.

  The friction drive actuator of the present invention includes a vibrating body that is fixed to a fixed member and performs in-plane vibration, and a rotor that includes the vibrating body, and the vibration of the vibrating body is transmitted to the rotor that is in frictional contact. In the friction drive actuator in which the rotor rotates, the rotor has rigidity, a first member that covers the vibrating body from one side, a second member that covers the vibrating body from the other side, and the first and first members The first member and the second member are formed in a bottomed cylindrical shape, and a second member is formed in the first member. Is fitted between the bottom plates, and the mortar-shaped tapered surface is formed on the vibration plate-facing surface of the bottom plate in at least one of the first and second members. It is characterized by having

  According to the above configuration, in a friction drive actuator called an ultrasonic actuator, which is preferably used for driving a magnetic recording head of an HDD, first, the friction drive actuator performs in-plane vibration, and a vibrating body serving as a stator And a rotor containing the vibrating body, and the vibration of the vibrating body is transmitted to the rotor in frictional contact so that the rotor rotates.

  If the plate-like vibrating body is, for example, in a horizontal state, the rotor is configured by a combination of a pair of upper and lower first and second members, and the first member has the vibrating body on one surface side. The second member covers from the other surface side, and they are displaced close to each other by the urging member to hold the vibrating body between them. Further, the first and second members are formed in a bottomed cylindrical shape (cap shape), and the second member is fitted into the first member like a cylinder and a piston, so that their bottom plates As described above, the vibrating body is held between the two, and the first outer member serves as an output transmission member. In the case of an HDD device, a head arm is attached.

  On the other hand, in at least one of the first and second members, a mortar-shaped taper surface is formed on the vibrating body facing surface of the bottom plate. That is, at least one of the first and second members is formed in a dome shape, and the tapered portion is in contact with the tip (plate-like edge) portion of the vibrating body obliquely, A pressing (friction) force is generated by the biasing member.

  Accordingly, by sandwiching a vibrating body that performs in-plane vibration between a pair of upper and lower first and second members having a tapered portion at least one, positioning (centering) of the rotor in the rotation axis direction and the axis perpendicular direction is both performed. A cylindrical portion having a configuration in which the bearing of the rotor is unnecessary and the force generated by the biasing member has a bottomed cylindrical (cap-shaped) rigidity in the first and second members. By sliding in the direction of the rotation axis, a pressure (friction) force that is even with respect to the circumferential direction of the contact portion and symmetrical with respect to the rotation axis is applied. As a result, even if there is a manufacturing error in the dimensions of the vibrating body or the rotor, it is possible to suppress fluctuations in the applied pressure with respect to the error amount. Further, even if a dimensional change occurs in the vibrating body or the rotor due to a temperature change or wear, it is possible to suppress a change in the applied pressure, and the applied pressure is stabilized. Thus, the error sensitivity with respect to the dimension of the applied pressure can be reduced, the frictional force between the vibrating body (stator) and the rotor can be further stabilized, and the driving performance can be stabilized.

  The friction drive actuator according to the present invention is characterized in that, on the outer peripheral surface of the cylindrical portion of the second member, a groove that is continuous in the circumferential direction is formed in the intermediate portion.

  According to said structure, in the outer peripheral surface of the cylindrical part in the said 2nd member used as the said piston, the center part of a rotating shaft direction is dented by the groove | channel formed in the circumferential direction, and only both ends are said 1st. The slider slides on the inner peripheral surface of the member.

  Therefore, the sliding resistance can be reduced and the frictional force can be made more stable without causing play in the sliding in the rotation axis direction. Grease or the like may be held in the groove.

  Furthermore, in the friction drive actuator of the present invention, one of a groove or a protrusion extending in the rotation axis direction is formed on an inner peripheral surface of the bottomed cylindrical first member, and an outer peripheral surface of the second member is formed. The other of the groove or the protrusion is formed.

  According to said structure, a said 1st member and a 2nd member come to rotate integrally, without shifting | deviating to the circumferential direction.

  Therefore, stable rotation can be performed.

  In the friction drive actuator according to the aspect of the invention, the vibrating body may be configured such that the first member covers the opposite side of the fixed member, the second member covers the fixed member, and the bottomed cylindrical shape. An end plate extending radially inward is fitted into the open end of the first member of the first member, and the biasing member is wound around the fixing member to form the bottomed cylindrical second member. It comprises a coil spring interposed between the bottom plate of the member and the end plate.

  According to the above configuration, if the plate-like vibrating body is in a horizontal state as described above, the vibrating body is fixed on the lower fixing member, and the first member covers the upper side from the upper side, and the second member The member has an opening into which the fixing member is loosely inserted and covers from below. And when the said urging | biasing member consists of a winding spring wound around the said fixing member, this winding spring is provided between the bottom plate of the said bottomed cylindrical said 2nd member, and a fixing member. Instead, it is provided at the open end of the first member having the bottomed cylindrical shape, and is provided between the end plate formed to extend inward in the radial direction.

  Therefore, the winding spring also rotates integrally with the first and second members, and a stable urging force can be exhibited and stable rotation can be performed.

  Furthermore, in the friction drive actuator of the present invention, an annular concave groove that prevents radial displacement of the winding spring is provided in at least one of the bottom plate and the end plate of the bottomed cylindrical second member. Alternatively, a protrusion is formed.

  According to said structure, the shift | offset | difference to the radial direction of the said winding spring is lose | eliminated, and more stable rotation can be performed.

  The hard disk device of the present invention uses the friction drive actuator as described above.

  Therefore, it is possible to realize a hard disk device having a head actuator that does not require a bearing and can further stabilize the frictional force between the vibrating body (stator) and the rotor.

  As described above, the friction drive actuator of the present invention includes a vibrating body that performs in-plane vibration and a rotor that includes the vibrating body, and the vibration of the vibrating body is transmitted to the rotor that is in frictional contact. In the friction drive actuator in which the rotor rotates, the rotor is configured by fitting the rigid first and second members having a bottomed cylindrical shape and holding the vibrating body between the bottom plates. Then, a mortar-shaped taper surface is formed on the vibration body facing surface of at least one bottom plate.

  Therefore, the bearing of the rotor is not required, and the frictional force between the vibrating body (stator) and the rotor is further increased by the rigidity of the cylindrical portions of the bottomed cylindrical first and second members. It is possible to stabilize the driving performance.

  The hard disk device of the present invention uses the friction drive actuator as described above.

  Therefore, it is possible to realize a hard disk device having a head actuator that does not require a bearing and can further stabilize the frictional force between the vibrating body (stator) and the rotor.

[Embodiment 1]
FIG. 1 is a longitudinal sectional view showing the structure of an ultrasonic motor 1 that is a friction drive actuator according to an embodiment of the present invention. The ultrasonic motor 1 generally includes a vibrating body 2 that performs in-plane vibration, a rotor 3 that includes the vibrating body 2, a winding spring 4 that is an urging member, and a fixed body that supports the vibrating body 2. And a member 15.

  FIG. 2 is a plan view of vibrating bodies 21, 22, and 23 that are one configuration example of the vibrating body 2. These vibrators 21, 22, and 23 are a plurality of vibrator main bodies 21a, 22a, and 23a each having electrodes 24 and 25 attached to both surfaces of a single-plate piezoelectric element, or a plurality of thin plate-like piezoelectric elements having electrodes attached to both surfaces. As shown in FIG. 1, chip members 21 b, 22 b, and 23 b each having a contact portion whose cross-section in the rotation axis direction of the rotor 3 has an arc shape are fixed to the edge of the laminated vibrator main body.

  The chip members 21b, 22b, and 23b can be made of wear-resistant material, for example, WC (tungsten carbide) -based cemented carbide, high-hardness ceramic such as alumina, or metal such as stainless steel. A member whose surface is hardened by quenching, nitriding, hard ceramic coating or the like is used. If these tip members 21b, 22b, and 23b are provided at three places like the tip members 21b and 23b, the rotor 3 can be supported geometrically and stably. Further, by providing four or more places like the tip member 22b, it is possible to reduce the pressurizing force supported at one place while maintaining the pressurizing force as a whole, which is advantageous for wear.

  The vibrating body 21 is formed by fixing the tip member 21b to the shaved vertex portion of the vibrating body main body 21a having a shape obtained by scraping the vertex of an equilateral triangle, and the position of the center of gravity serving as a vibration node is fixed. The member 15 is fixed by screwing or bonding (using the fixing screw 16 in the example of FIG. 1). In the case of the vibrating body 21 made of a single-plate piezoelectric element, the electrode 24 is formed on one surface of the vibrating body 21 symmetrically with respect to a line connecting each vertex from the center of gravity, as shown in FIG. A common electrode is formed on the other surface, and when a predetermined drive signal is input to these electrodes from a drive signal generator (not shown) via an FPC (not shown), each vertex of the vibrating body 21 As the piezoelectric element expands and contracts and bends (the tip portion of the chip member 21b), high-frequency elliptical vibrations rotating in the same direction as indicated by reference numeral 17 in the cross section perpendicular to the axis of the rotor 3 are excited. Functions as a standing wave motor. The vibration generation process by the triangular vibrator 3 is described in detail in Japanese Patent Application No. 2007-184175 by the applicant of the present application.

  The vibrators 22 and 23 are formed by fixing the tip members 22b and 23b to corners or central parts of rectangular vibrator bodies 22a and 23a, and similarly, the center of gravity position serving as a vibration node is fixed. The member 15 is fixed with a fixing screw 16. In the case of the vibrating bodies 22 and 23 made of a single-plate piezoelectric element, as shown in FIGS. 2 (b) and 2 (c), the center portion of each side is connected to the one surface from the center of gravity. The electrode 25 is formed symmetrically with respect to the line, and a common electrode is formed on the other surface. When a predetermined drive signal is input to these electrodes, the vibrating bodies 22 and 23 At each apex (tip portions of the chip members 22b and 23b), the piezoelectric element is expanded and bent and displaced, so that the high frequency rotates in the same direction as indicated by the reference numeral 17 in the cross section perpendicular to the axis of the rotor 3. Is excited.

  When the elliptical vibration is clockwise, the rotor 3 rotates clockwise, and when it is counterclockwise, the rotor 3 rotates counterclockwise. Thus, the ultrasonic motor 1 functions as a standing wave motor. The rotational speed and torque of the rotor 3 can be changed by changing the magnitude of the elliptical vibration. The vibration generating process by the rectangular vibrating bodies 22 and 23 is described in detail in Japanese Patent Application No. 2007-48787 by the applicant of the present application.

  In this embodiment, as in Patent Document 4, a disk-shaped vibrating body 131 (shown in FIGS. 8 and 12) is provided, and the vibration progresses in the circumferential direction of the vibrating body 131. A configuration as a wave motor can also be used.

  Referring to FIG. 1, it should be noted that in the present embodiment, the rotor 3 includes a first member 31 that covers the vibrating body 2 from the side opposite to the fixing member 15, and the fixing member 15 side. And a second member 32 that covers each other, each having rigidity, formed in a bottomed cylindrical shape (cap shape), and in the first member 31 like a cylinder and a piston. This means that the vibrating body 2 is included between the bottom plates 31a and 32a. An end plate 6 extending radially inward is fitted into the open end 31 b of the bottomed cylindrical first member 31, and the winding spring 4 is wound around the fixing member 15. And is interposed between the end plate 6 and the bottom plate 31a of the bottomed cylindrical second member 31, and urges the second member 32 to be displaced close to the first member 31 side. Thus, the vibrating body 2 is sandwiched and held between the bottom plates 31a and 32a.

  Further, at least one of the first member 31 and the second member 32 (both in the example of FIG. 1), mortar-shaped tapered surfaces 31c and 32c are formed on the opposing surfaces of the vibrating body 2 of the bottom plates 31a and 32a. Is formed. That is, at least one of the first and second members 31 and 32 is formed in a dome shape, and the tapered surfaces 31c and 32c are formed at the tip of the vibrating body 2 (the tip members 21b, 22b, and 23b). The winding spring 4 generates pressure (friction) force in contact with each other at an angle. Spaces 7a and 7b formed by the tapered surfaces 31c and 32c and the arc shapes of the chip members 21b, 22b and 23b are filled with grease.

  Therefore, a metal material is used for the rotor 3. In order to prevent wear due to contact with the vibrating body 2, the surface is previously subjected to hardening treatment such as quenching and nitriding treatment. Further, a ceramic coating such as CrN or TiCN may be performed.

  Further, on the outer peripheral surface of the cylindrical portion 32d of the second member 32 serving as the piston, the central portion in the rotation axis direction is recessed with a groove 32e continuous in the circumferential direction, and only both ends 32f and 32g are the first. It is a slider that slides on the inner peripheral surface of the cylindrical portion 31d of one member. Furthermore, the inner peripheral surface of the cylindrical portion 31d of the first member 31 having the bottomed cylindrical shape has grooves or protrusions extending in the direction of the rotation axis at one or a plurality of locations (at least two in the example of FIG. 1). One (groove in FIG. 1) 31h is formed, and the other of the grooves or protrusions (projection in FIG. 1) 32h is formed on the outer peripheral surface of the cylindrical portion 32d of the second member 32.

  Incorporating the vibrator 2 into the rotor 3 accommodates the vibrator 2 in the first member 31 that is turned upside down with the first member 31 and the second member 32 separated from each other. After that, the second member 32 is fitted into the first member 31 such that the projection 32h thereof matches the groove 31h, and the winding spring 4 is mounted on the bottom plate 32a of the second member 32. It is completed by fitting the end plate 6. The end plate 6 may be appropriately joined to the first member 31 by adhesion, caulking, welding, or the like. The FPCs for the electrodes 24 and 25 of the vibrators 21, 22 and 23 are appropriately connected, and the opening 32 j formed for connection to the fixing member 15 at the center of the bottom plate 32 a of the second member 32. Has been drawn from. Then, the ultrasonic motor 1 is fixed to the fixing member 15 by screwing the fixing screw 16 inserted through the opening 31j formed in the central portion of the bottom plate 31a of the first member 31 to the fixing member 15. As shown in FIG.

  Thus, the rotor 3 is constituted by the first and second members 31 and 32 having the tapered surfaces 31c and 32c, and the vibrating body 2 is placed in the annular V-shaped groove formed by the tapered surfaces 31c and 32c. The tip portions of the tip members 21b, 22b, and 23b are fitted, and the rotor 3 is vibrated by elastically urging the second member 32 toward the first member 31 by the winding spring 4. The movement in the rotation axis direction and the radial direction with respect to the body 2 are both regulated without backlash (both centering is performed), and only rotation is possible. Further, the force generated by the coil spring 4 is caused by the sliding of the cylindrical portions 31d and 32d having the bottomed cylindrical (cap-shaped) rigidity in the first and second members 31 and 32 in the rotation axis direction. A pressing (friction) force is applied equally to the circumferential direction of the contact portion of the tip members 21b, 22b, and 23b and symmetrical with respect to the rotation axis.

  As a result, even if there are dimensional manufacturing errors in the vibrating body 2 and the rotor 3, fluctuations in the applied pressure with respect to the error amount can be suppressed to a small level. Further, even if a dimensional change occurs in the vibrating body 2 or the rotor 3 due to a temperature change, wear, or the like, it is possible to suppress a change in the applied pressure, and the applied pressure is stabilized. Thus, even if a conventional ball bearing or the like is not required, the error sensitivity to the applied pressure can be reduced, the frictional force between the vibrating body (stator) 2 and the rotor 3 is further stabilized, and the driving performance is stabilized. be able to. The tip portions of the chip members 21b, 22b, and 23b in the vibrating body 2 do not have to be formed in an arcuate cross section (R shape) as shown in FIG. Wear is likely to occur due to contact.

  Further, by forming a circumferentially extending groove 32e on the outer peripheral surface of the cylindrical portion 32d of the second member 32, sliding resistance is reduced without causing backlash in sliding in the rotational axis direction. Thus, the frictional force can be further stabilized. Grease or the like may be held in the groove.

  Furthermore, a groove 31h is formed on the inner peripheral surface of the cylindrical portion 31d of the first member 31, and a corresponding projection 32h is formed on the outer peripheral surface of the cylindrical portion 32d of the second member 32. The first member and the second member rotate integrally without being displaced in the circumferential direction, and can perform more stable rotation.

  Further, the coil spring 4 that biases the second member 32 toward the first member 31 is not provided between the bottom plate 32a of the second member 32 and the fixing member 15, but the first member. 31 is provided between the end plate 6 fitted in the open end 31b of the cylindrical portion 31d of the cylinder 31d. Therefore, the winding spring 4 also rotates integrally with the first and second members 31 and 32, and is stably attached. Power can be exerted and stable rotation can be performed.

  FIG. 3 is a schematic configuration diagram of an HDD device 12 in which the ultrasonic motor 1 shown in FIG. 1 is applied to drive the HDD magnetic recording head 11. As a conventional HDD magnetic recording head drive actuator, the head arm 13 to which the magnetic recording head 11 is attached is rotatably supported by a pivot bearing and driven by a VCM (voice coil motor). In contrast, in the present embodiment, the head arm 13 is rotationally supported by the ultrasonic motor 1 and is also driven.

  Specifically, the ultrasonic motor 1 is disposed on the side of the disk 14 to be rotationally driven, and is formed into the bottomed cylindrical shape (cap shape) with the ultrasonic motor 1 as a rotation axis and is rigid. The head arm 13 is fixed to the outer peripheral surface of the first member 31 serving as an output transmission member and the end portion of the cylindrical portion 31d, and the HDD magnet is attached to the tip of the head arm 13. The recording head 11 travels in the circumferential direction on the rotationally driven disk 14 so that recording contents are written, erased, read out, and the like. By using the first member 31 having a bottomed cylindrical shape (cap shape) and rigidity in this manner as an output transmission member, it becomes easy to take out the output.

  Then, the ultrasonic motor 1 is driven by a control means (not shown), and the HDD magnetic recording head 11 is moved in the radial direction of the disk 14, whereby a search operation is realized, and the writing, erasing, Reading is performed.

  In the case of such an HDD head drive, it is necessary to perform positioning control while following the waviness of the track on the disk 14 rotating at high speed, and the actuator is required to have very high responsiveness and resolution. When the above-described ultrasonic motor 1 is used to drive the magnetic recording head 11 as in the present embodiment, there is no bearing inertia or bearing load in the bearing backlash, and the friction between the vibrating body (stator) 2 and the rotor 3 does not occur. Since the force can be further stabilized, high responsiveness can be obtained and the recording density can be improved.

[Embodiment 2]
FIG. 4 is a longitudinal sectional view showing the structure of an ultrasonic motor 1 ′ which is a friction drive actuator according to another embodiment of the present invention. This ultrasonic motor 1 ′ is similar to the above-described ultrasonic motor 1, and corresponding portions are denoted by the same reference numerals and description thereof is omitted. It should be noted that in this ultrasonic motor 1 ′, at least one of the bottom plate 32a of the bottomed cylindrical second member 32 ′ and the end plate 6 ′ (both in FIG. 4) is provided in the rotor 3 ′. The annular grooves or protrusions (protrusions in the example of FIG. 1) 32k and 6k that prevent the winding spring 4 from shifting in the radial direction are formed. By comprising in this way, the shift | offset | difference to the radial direction of the said winding spring 4 is lose | eliminated, and more stable rotation can be performed.

  As described above, the winding spring 4 is provided between the bottom plate 32a of the second members 32 and 32 ′ and the end plates 6 and 6 ′, and rotates together with the first and second members 31 and 32. Therefore, the portions of the seats 4a and 4b at both ends of the winding spring 4 may be fixed to the bottom plate 32a and the end plates 6 and 6 ′ with an adhesive or the like. Further, the urging member is not limited to the winding spring 4, and other configurations may be used as long as the urging member uniformly pressurizes the circumferential direction of the bottom plate 32 a such as a rubber cylinder.

It is a longitudinal cross-sectional view which shows the structure of the ultrasonic motor which is a friction drive actuator which concerns on one Embodiment of this invention. It is a top view of an example of 1 composition of a vibrating body in an ultrasonic motor. It is a schematic block diagram of the HDD apparatus which applied the ultrasonic motor shown in FIG. 1 to the drive of HDD magnetic recording head. It is a longitudinal cross-sectional view which shows the structure of the ultrasonic motor which is a friction drive actuator which concerns on other forms of implementation of this invention. 1 is a cross-sectional view of a typical conventional ultrasonic actuator for driving a magnetic recording head of an HDD. FIG. It is a longitudinal cross-sectional view of another prior art. It is a top view of other prior art. It is sectional drawing which expands and shows a part of other prior art further.

Explanation of symbols

1, 1 'Ultrasonic motor 2, 21, 22, 23 Vibrator 3, 3' Rotor 4 Winding springs 4a, 4b Seat 6, 6 'End plate 6k, 32k Protrusion 11 Magnetic recording head 12 HDD device 13 Head arm 14 Disc 15 Fixing member 16 Fixing screw 24, 25 Electrodes 21a, 22a, 23a Vibrating body main bodies 21b, 22b, 23b Tip member 31 First member 31a, 32a Bottom plate 31b Open end 31c, 32c Tapered surface 31d, 32d Cylindrical portion 31h Groove 32, 32 'second member 32e groove 32f, 32g both ends 32h protrusion

Claims (6)

Friction drive that is configured to include a vibrating body that is fixed to a fixed member and that performs in-plane vibration and a rotor that includes the vibrating body, and that the vibration of the vibrating body is transmitted to a rotor that is in frictional contact to rotate the rotor. In the actuator
The rotor has rigidity so that the first member that covers the vibrating body from one side and the second member that covers the vibrating body from the other side, and the first and second members are displaced in proximity to each other. A biasing member that biases,
The first and second members are formed in a bottomed cylindrical shape, and the second member is fitted into the first member, whereby the vibrating body is sandwiched and held between the bottom plates. At least one of the first member and the second member has a mortar-shaped taper surface on the vibration member-facing surface of the bottom plate.   The friction drive actuator according to claim 1, wherein a groove that is continuous in a circumferential direction is formed in an intermediate portion of the outer peripheral surface of the cylindrical portion of the second member.   One of a groove or a protrusion extending in the rotation axis direction is formed on the inner peripheral surface of the bottomed cylindrical first member, and the other of the groove or the protrusion is formed on an outer peripheral surface of the second member. The friction drive actuator according to claim 1 or 2. The vibrating member, the first member covers from the side opposite to the fixing member, the second member covers from the side of the fixing member,
An end plate extending inward in the radial direction is fitted into the open end of the first member having the bottomed cylindrical shape,
The urging member is a winding spring wound around the fixed member and interposed between a bottom plate and the end plate of the bottomed cylindrical second member. Item 4. The friction drive actuator according to any one of Items 1 to 3.   An annular concave groove or protrusion for preventing displacement of the winding spring in the radial direction is formed on at least one of the bottom plate and the end plate of the bottomed cylindrical second member. The friction drive actuator according to claim 4.   6. A hard disk drive using the friction drive actuator according to claim 1.

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