JP2009055779A - Ultrasonic actuator, magnetic recording apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic actuator for stably obtaining a superior drive performance without complicating an apparatus and increasing a cost, and a magnetic recording apparatus. <P>SOLUTION: The ultrasonic actuator has a triangular vibrating object provided with a piezoelectric displacement section to be expanded and contracted by a drive signal, and moving objects contacting three peaks of the vibrating object by an applied pressure and moving relatively to the vibrating object. The vibrating object is expanded, contracted and deformed by expansion and contraction of the piezoelectric displacement section in a stretching vibration mode in which one peak is reciprocated in the direction along a line for connecting the peak and the gravity center of the vibrating object. The vibrating object is bent and deformed by expansion and contraction of the piezoelectric displacement section in a flexing vibration mode in which one peak is reciprocated in the direction vertical to the direction of reciprocation movement in the stretching vibration mode. The stretching vibration mode and the flexing vibration mode are excited by resonance in the moving objects. Since three peaks of the vibrating object elliptically vibrates in the same rotating direction, movement is generated relatively to the vibrating object. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an ultrasonic actuator and a magnetic recording apparatus, and more particularly to an ultrasonic actuator and a magnetic recording apparatus that generate relative movement by pressing a moving body against a vibrating body.

  In the past, attempts have been made to use ultrasonic actuators in various mobile devices. An ultrasonic actuator is generally composed of a vibrating body including a piezoelectric element that is an electro-mechanical energy conversion element, a driven body (moving body) that contacts the vibrating body in a pressurized state, and the like. The ultrasonic actuator is brought into pressure contact with the vibrating body by inputting a drive signal to the vibrating body, causing the vibrating body to expand and contract, and causing part of the vibrating body to perform elliptical vibration (hereinafter, including circular vibration). A relative motion is generated between the driven body and the driven body by a frictional force.

  Ultrasonic actuators are small, excellent in quietness, and capable of high-speed, high-accuracy positioning control, so they have been used as drive devices for electronic devices such as electronic cameras, and their applications are further expanded. It's getting on.

  On the other hand, in recent years, as electronic devices have been reduced in size and performance, there has been a demand for better driving performance of ultrasonic actuators used as driving devices.

  In order to meet such requirements, various studies have been made to increase the driving efficiency of the ultrasonic actuator.

For example, an equilateral triangular piezoelectric vibrator is provided, and the electrode is divided into two by a line connecting the midpoints of the opposite sides from one apex that becomes the contact point with the moving body, and elliptical vibration occurs at one apex that becomes the contact point A rotary drive type ultrasonic actuator that excites the motor and frictionally drives a moving body is known (see Patent Document 1). In addition, an ultrasonic motor that uses a plurality of ultrasonic transducers and rotates while holding the rotor is known (see Patent Document 2).
JP-A-8-322270 JP 2000-152671 A

  The piezoelectric vibrator disclosed in Patent Document 1 excites elliptical vibration at a contact point with a moving body by exciting and synthesizing longitudinal vibration and bending secondary mode. However, in such a driving method using the vibration mode, the desired elliptical vibration is excited only at the contact point, and the other vertexes vibrate passively, and the elliptical locus and the rotation direction are different. Drive loss occurs when touching. For example, when driving the inner peripheral surface of a rotor (moving body), the center of rotation of the rotor is not determined at one point, and thus a member such as a bearing that holds the rotor is required. For this reason, there are problems such as a decrease in drive efficiency due to a drive loss due to a bearing load, a complicated configuration, and a high price.

  Moreover, since the ultrasonic motor disclosed in Patent Document 2 requires a plurality of ultrasonic transducers, there is a problem in that the configuration is complicated and the cost is increased.

  The present invention has been made in view of the above problems, and provides an ultrasonic actuator and a magnetic recording apparatus that can stably obtain excellent driving performance without causing complication and cost increase of the apparatus. The purpose is to do.

  The above object is achieved by the invention described in any one of 1 to 8 below.

1. A substantially triangular vibrating body having a piezoelectric displacement portion that expands and contracts by a drive signal;
A movable body that is in pressure contact with the three vertices of the vibrating body and generates a relative movement with respect to the vibrating body;
The vibrator is
Expansion and deformation by expansion and contraction of the piezoelectric displacement portion,
One of the vertexes is a stretching vibration mode in which the vertex reciprocates in a direction connecting the vertex and the center of gravity of the vibrating body;
Bending and deforming due to expansion and contraction of the piezoelectric displacement part,
One of the apexes has a bending vibration mode that reciprocates in a direction perpendicular to the direction of the reciprocating movement by the stretching vibration mode,
The moving body is
The stretching vibration mode and the bending vibration mode are resonantly excited, and the three vertices of the vibrating body perform elliptical vibration in the same rotational direction, thereby causing relative movement with respect to the vibrating body. Ultrasonic actuator.

  2. 2. The ultrasonic wave according to claim 1, wherein the piezoelectric displacement portion includes a pair of A-phase electrode and B-phase electrode to which the drive signal is supplied, corresponding to the three apexes of the vibrating body. Actuator.

3. A drive signal generator for generating the drive signal;
The resonance frequency of the stretching vibration mode and the bending vibration mode are the same value,
The drive signal generation unit generates two-phase AC voltages having frequencies close to the resonance frequency and different phases, and supplies the two-phase AC voltages to the A-phase electrode and the B-phase electrode, respectively. The described ultrasonic actuator.

  4). 4. The ultrasonic actuator according to any one of 1 to 3, wherein the vibrating body has an equilateral triangle shape.

5). The moving body has a cylindrical shape and performs a rotational motion with respect to the vibrating body,
The inner peripheral surface of the cylindrical movable body circumscribes the three vertices of the vibrating body, and is in pressure contact with the three vertices of the vibrating body by the elastic force of the moving body. The ultrasonic actuator according to any one of 1 to 4.

  6). 6. The ultrasonic actuator according to claim 1, wherein the vibrating body is held and fixed by a holding member in the vicinity of the center of each of the three sides of the vibrating body.

  7. 6. The ultrasonic actuator according to any one of claims 1 to 5, wherein the vibrating body is held and fixed by a holding member in the vicinity of the center of gravity of the vibrating body.

8). A recording medium for recording information;
A magnetic head for reading and writing the information on the recording medium;
An arm that supports the magnetic head to be movable relative to the recording medium;
The ultrasonic actuator according to any one of 1 to 7 above,
The magnetic recording apparatus according to claim 1, wherein the arm is fixed to the moving body provided in the ultrasonic actuator.

  According to the present invention, the mobile body is vibrated by resonance-exciting the stretching vibration mode and the bending vibration mode, and causing the three vertices of the vibration body that is in pressure contact with the mobile body to perform elliptical vibration in the same rotational direction. Moved relative to the body. That is, since the moving body is relatively moved while being held at the three apexes of the substantially triangular vibrating body, the posture of the moving body is stabilized and can be moved with high accuracy. Moreover, since the location which hold | maintains a moving body other than the three vertices of a vibrating body is not required, a driving loss is suppressed and high driving efficiency can be obtained. Furthermore, since the resonance frequencies of the two vibration modes always match, there is a high degree of freedom in designing the vibrating body, and there is no performance degradation due to errors in the resonance frequencies of the two vibration modes at the time of manufacture. It can be performed. As a result, it is possible to realize an ultrasonic actuator that can stably obtain excellent driving performance without increasing the complexity and cost of the apparatus.

  Further, by using the ultrasonic actuator having such a configuration for driving the head of the magnetic recording apparatus, the moving accuracy and responsiveness of the head can be increased, and the recording density of the magnetic recording apparatus can be increased.

  Embodiments of an ultrasonic actuator and a magnetic recording apparatus according to the present invention will be described below with reference to the drawings. In addition, although this invention is demonstrated based on embodiment of illustration, this invention is not limited to this embodiment. In addition, the same or corresponding parts in the embodiments are denoted by the same reference numerals, and repeated description is appropriately omitted.

Embodiment 1
First, the configuration of the ultrasonic actuator 5 according to the first embodiment will be described with reference to FIG. FIG. 1A is a front view showing an outline of the overall configuration of the ultrasonic actuator 5, and FIG. 1B is a cross-sectional view taken along line AA ′ in FIG.

  As shown in FIG. 1A, the ultrasonic actuator 5 includes a vibrating body 10, a rotor 20, an FPC 30, a fixing member 40, and the like.

  The vibrating body 10 has an equilateral triangle shape, and a cylindrical rotor 20 circumscribes each vertex of the equilateral triangle. Before the rotor (moving body) 20 is incorporated into the vibrating body 10, the dimensions of the contact points are set smaller than the dimensions of the vibrating body 10, and the parts other than the contact portion are elastically deformed by being incorporated. (In the assembled state, the rotor 20 is slightly triangular.) A predetermined pressing force is applied to each contact portion of the vibrating body 10 by the rotor 20.

  As shown in FIG. 1B, a V-shaped groove 20 a is formed in the circumferential cross section of the rotor 20. Since the three convex-shaped tip members 103 (described later) provided at the apexes of the vibrating body 10 are fitted into the V-shaped grooves 20a of the rotor 20, the swinging in the thrust direction is restricted, and the rotor 20 has a high height. The rotation can be performed with high accuracy.

  As will be described later, the vibrating body 10 is held by three fixing pins (holding members) 401 provided on the fixing member 40 in the vicinity of the center of each side where vibration is relatively small. Holding is performed by press-fitting or adhesion. Further, positioning with respect to the fixing member 40 may be performed by providing a notch in the vicinity of the center of each side of the vibrating body 10 and holding it by the fixing pin 401. The ultrasonic actuator 5 is positioned by fixing the fixing member 40 to, for example, a case or a frame of a magnetic recording apparatus described later.

  FIG. 2 shows a fixing method according to another example of the vibrating body 10. FIG. 2A is a front view showing an outline of the vibrating body 10, and FIG. 1B is a cross-sectional view taken along the line AA 'in FIG.

  As shown in FIG. 2B, a through hole 10a may be provided at the center of gravity of the vibrating body 10 and fixed using a screw (holding member) 403 or the like. Since the position of the center of gravity hits a vibration node, the influence on vibration due to fixation can be minimized.

  The material of the rotor 20 is preferably a highly elastic material, and a metal material such as stainless steel is used. In order to prevent wear, the surface is subjected to a hardening process such as a nitriding process. Moreover, you may perform ceramic coating, such as CrN and TiCN.

  An FPC (flexible printed wiring board) 30 is connected to the vibrating body 10, and a predetermined drive signal is input via the FPC 30 from a drive signal generation unit 7 (not shown) described later.

  When a drive signal is input to the vibrating body 10, high-frequency elliptical vibrations that rotate in the same direction are generated in three chip members 103 (described later) provided at each vertex of the vibrating body 10. Since the rotor 20 is in contact with the tip member 103 with a predetermined pressing force, the rotor 20 rotates by frictional force. In FIG. 1A, when each vertex performs elliptical vibration in the clockwise direction, the rotor 20 also rotates clockwise, and when each vertex performs elliptical vibration in the counterclockwise direction, the rotor 20 also rotates in the counterclockwise direction. Rotate. The speed and torque can be changed by changing the magnitude of the elliptical vibration.

  Since the rotor 20 is held by the three tip members 103 provided at the apex of the equilateral triangular vibrating body 10, the posture stability in the radial direction is very high, and the V-shaped groove is formed in the thrust direction. Since the swinging is restricted by 20a, there is no center deflection and the rotation is possible with very high accuracy. Further, since there is no backlash, the rigidity is high and the responsiveness of the motor can be improved. Moreover, since the location which hold | maintains the rotor 20 other than the three vertexes of the vibrating body 10 is not required, a drive loss is suppressed and high drive efficiency can be obtained.

  Next, the configuration of the vibrating body 10 will be described with reference to FIG. 3A is a front view showing the configuration of the vibrating body 10, FIG. 3B is a side view, and FIG. 3C is a back view.

  As shown in FIG. 3A, the vibrating body 10 includes three chip members (contact members) 103 that contact the rotor 20 and a piezoelectric member 101 in which a flat portion is formed at the apex of an equilateral triangle. The chip member 103 is coupled to the piezoelectric member 101 by adhesion. For bonding, an epoxy adhesive having high adhesive strength and high rigidity is used.

  As the material of the chip member 103, high hardness ceramics such as alumina and zirconia, cemented carbide or the like is used to prevent wear.

  The piezoelectric member 101 is made of a piezoelectric material exhibiting piezoelectric characteristics such as PZT (lead zirconate titanate), and a driving electrode is formed on the surface of the piezoelectric member a, and a common thin film electrode (GND electrode) 101c is formed on the surface b. . The electrode is made of silver or silver palladium and is formed by vapor deposition or the like. As shown in FIG. 3 (a), the driving electrode has a shape (six divisions) divided by each perpendicular extending from each vertex of the vibrating body 10 to the opposite side, and a pair of A-phase electrode regions at each vertex. , B-phase electrode regions, and each A-phase electrode 101a and each B-phase electrode 101b are commonly connected via the FPC 30. By connecting the FPC 30 in the vicinity of the position of the center of gravity of the triangle, which is a vibration node described later, the influence on the vibration can be minimized. For the connection, solder, conductive adhesive, or the like is used.

  Next, a method for driving the ultrasonic actuator 5 having such a configuration will be described. The basic driving method is elliptical vibration driving using resonance for rotating the rotor 20. This is a method of exciting and driving an elliptical vibration at each vertex of the vibrating body 10 by using resonance, and the amplitude can be expanded several tens of times, and a large elliptical vibration can be obtained efficiently at a low voltage. The principle and driving characteristics will be described below.

(Eigen mode)
First, the eigenmode will be described with reference to FIG. In order to excite elliptical vibration in the same rotational direction at each vertex of the vibrating body 10, in this embodiment, two eigenmodes shown in FIG. 4 are used. FIG. 4A is a schematic diagram illustrating a state of deformation of the vibrating body 10 in the stretching vibration mode, and FIG. In the stretching vibration mode, the vibrating body 10 expands and contracts in the vertical direction of the paper surface, and the vertex 10p reciprocates in the direction connecting the vertex 10p and the gravity center position G. In the bending vibration mode, the vicinity of the vertex 10p is bent and deformed, and the vertex 10p reciprocates in a direction perpendicular to the reciprocating motion direction in the stretching vibration mode. FIG. 4 shows the modes shown for the deformation of the vertex 10p. Since the vibrating body 10 is rotationally symmetric with respect to the position of the center of gravity G, these modes can be excited for each vertex. is there.

  Further, by inputting a driving signal that matches the resonance frequency of the same phase or opposite phase to the A-phase electrode 101a and the B-phase electrode 101b at each vertex, the stretching vibration mode is simultaneously applied to each vertex 10p, 10q, 10r, or It is possible to excite the bending vibration mode. FIG. 11 shows how the vibrating body 10 is deformed in this case. FIG. 11A is a schematic diagram showing a state of deformation of the vibrating body 10 when the stretching vibration mode is excited at three vertices and FIG. 11B is a bending vibration mode excited at the three vertices. In the stretching vibration mode, the center of gravity position G of the vibrating body 10 is set as a vibration node, the three-divided region including each vertex is stretched and deformed, and each vertex reciprocates radially in the same phase. In the bending vibration mode, the center of gravity position G of the vibrating body 10 is set as a vibration node, the three-divided region including each vertex is bent and deformed, and the circumscribing of the vibrating body 10 is centered on the center of gravity position G in the same phase. Reciprocates in the tangential direction of the circumference of the circle. In both the stretching vibration mode and the bending vibration mode, the position of the center of gravity G is a node of vibration, and the center position of the three sides is relatively small in vibration. Can be suppressed.

  In addition, it can be confirmed by simulation that the resonance frequencies of the above-mentioned two natural modes always match regardless of the mass and size of the tip member 103, the hole diameter at the center of gravity, the fixed state of the vibrating body 10, and the like. As a result, the degree of freedom in design such as the fixing method of the chip member 103 and the vibrating body 10 is high, and there is no performance degradation due to the shift of the resonance frequency between the natural modes at the time of manufacture. be able to.

(Phase difference driving method)
The phase difference driving method will be described with reference to FIGS. FIG. 12 is a block diagram illustrating an example of the drive signal generation unit 7, and FIG. 13 is a diagram illustrating an example of the drive signals VA and VB.

  First, the configuration of the drive signal generation unit 7 will be described with reference to FIG. As shown in FIG. 12, the drive signal generation unit 7 includes a control unit 71, an oscillation unit 72, a phase change unit 73, an amplification unit 74, and the like.

  The oscillating unit 72 is an oscillator that oscillates a signal having a predetermined frequency that is the basis of the drive signals VA and VB.

  The phase changing unit 73 adjusts the phase of the signal from the oscillating unit 72 and generates two signals having different phases.

  The amplifying unit 74 amplifies the signal generated by the phase changing unit 73 to generate drive signals VA and VB, and applies them to the A phase electrodes 101 a and B phase electrodes 101 b of the vibrating body 10.

  The control unit 71 detects the driving state of the rotor 20 based on the output of the speed detector 75 or the like that detects the rotational speed of the rotor 20 provided in the ultrasonic actuator 5, and the oscillation unit 72, the phase change unit 73, and the amplification The drive characteristics (speed, torque, etc.) are controlled by controlling the unit 74 and adjusting the frequency, phase difference, and amplitude of the drive signals VA, VB.

  Next, a phase difference driving method will be described. By inputting the drive signals VA and VB having the same frequency as the resonance frequency of the natural mode with a phase shift of 90 ° as shown in FIG. 13, for example, to the A-phase electrode 101a and the B-phase electrode 101b at each vertex. The eigenmodes are excited and synthesized, and elliptical vibrations in the same rotational direction are generated at each vertex of the vibrating body 10. By reversing the phases of the drive signals VA and VB, the rotational direction of the elliptical vibration is reversed. Further, by changing the amplitude and phase of the drive signals VA and VB, the locus shape and size of the elliptical vibration can be changed.

  The elliptical locus diameter changes in proportion to the amplitude (voltage). Further, the elliptical shape can be changed by changing the phase difference between the drive signals VA and VB. FIG. 5 is a schematic diagram showing how the elliptical locus changes with respect to the phase difference between the drive signals VA and VB. 5A shows a case where the phase difference between the drive signals VA and VB is 45 °, FIG. 5B shows 90 °, and FIG. 5C shows 135 °. When the phase difference decreases, the elliptical diameter in the normal direction N at the contact point with the rotor 20 increases, and when the phase difference increases, the diameter in the tangential direction T increases. By changing the elliptical trajectory shape, the drive characteristics can be changed, as will be described later, so that it can be applied to speed control and position control. In addition, by performing phase difference driving driven by the two-phase driving signals VA and VB, it is possible to drive at a low voltage and drive control based on the phase difference is possible.

(Other driving methods)
A driving method according to another example will be described with reference to FIGS. FIG. 14 is a block diagram showing another example of the drive signal generator 7, and FIG. 15 is a diagram showing another example of the drive signals VA and VB.

  First, the configuration of the drive signal generation unit 7 will be described with reference to FIG. As shown in FIG. 14, the drive signal generation unit 7 according to the present embodiment is different from the drive signal generation unit 7 shown in FIG. 12 in the configuration of the phase change unit 73 and the amplification unit 74. The part configuration is the same.

  The phase changing unit 73 according to the present embodiment adjusts the phase of the signal from the oscillating unit 72, generates a pair of two signals having different phases, and generates three pairs of signals having different phases for each pair.

  The amplifying unit 74 amplifies the three pairs of signals generated by the phase changing unit 73 to generate driving signals VAp, VBp, VAq, VBq, VAr, and VBr, and each vertex 10p, 10q, 10r of the vibrating body 10, respectively. Are applied to the A-phase electrode 101a and the B-phase electrode 101b.

  By configuring the FPC 30 and the drive signal generation unit 7 and the like in this way so that drive signals can be input independently without connecting the A-phase electrode 101a and the B-phase electrode 101b at each vertex of the vibrating body 10 in common. It is also possible to drive the three vertices selectively or out of phase.

  For example, driving signals VAp and VBp are input only to the A-phase electrode 101a and the B-phase electrode 101b at the vertex 10p, and only one vertex 10p is driven, thereby reducing the driving characteristics and driving at low speed and low power consumption. Can do.

  Further, by inputting three pairs of drive signals VAp, VBp, VAq, VBq, VAr, VBr having phases shifted by 120 ° as shown in FIG. 15 to the respective electrodes at the apexes 10p, 10q, 10r, The phase of the elliptical vibration at the apex can be shifted by 120 °. The tip member 103 repeats contact / separation with the rotor 20 due to elliptical vibration. When the phase difference between the three vertices is 0 °, the tip member 103 performs contact / separation at the same time. 20 slightly decelerates while running idle, and repeats minute acceleration / deceleration that accelerates when the tip member 103 comes into contact. By shifting the phase of the elliptical vibration of the tip members 103 at the three apexes, the timing of contact / detachment is shifted, and any one of the tip members 103 is always in contact with the rotor 20 and is given a driving force. Accordingly, minute acceleration / deceleration is eliminated, and driving stability is improved.

(Oval trajectory and drive performance)
Here, the relationship between the elliptical trajectory and the driving performance will be described with reference to FIG. When the elliptical vibration generated in the tip member 103 is decomposed into the tangential direction T and the normal direction N of the rotor 20, the speed of the rotor 20 is determined by the speed of the tip member 103 in the direction of elliptic motion T. It is determined by the diameter Rt of T and the driving frequency, and the speed increases as Rt increases. On the other hand, the driving force is determined by the product of the applied pressure and the friction coefficient of the contact point, but the diameter Rn in the normal direction N of the elliptical locus is also related. This is because when the applied pressure is relatively low with respect to the diameter Rn in the pressurizing direction of the elliptical locus, the tip member 103 is driven by frictional force during contact while repeatedly making contact with and separating from the rotor 20. However, when the pressure is relatively large with respect to the diameter Rn, elliptical vibration is performed in a constantly contacted state due to elastic deformation of the rotor 20 and the contact portion surface and elastic deformation of the structural member that receives the applied pressure. . In this state, since the friction force acts and acts as a brake even when the tip member 103 moves in the counter-drive direction during the vibration cycle, a drive force exceeding the value determined by Rn is not generated even if the applied pressure is increased. In the driving in such a state, the driving state such as speed unevenness and reproducibility becomes unstable, and there may be a problem such as abnormal noise. Therefore, the driving force increases as the diameter Rn of the elliptical locus in the pressing direction increases, and stable driving is possible.

  Therefore, the elliptical trajectory shown in FIG. 5A has a low speed and high torque characteristic, and the elliptical trajectory shown in FIG. 5C has a high speed and low torque characteristic. By changing the phase difference between the drive signals VA and VB, driving The performance can be controlled, and high-precision driving such as constant speed control and positioning control can be performed.

(DC drive)
Next, DC driving will be described. The DC drive is a driving method for swinging the rotor 20 minutely, and is used when very high-precision positioning is required, and a positioning resolution on the order of nm can be obtained. After performing coarse movement (high speed, wide rotation angle drive) by the above-described resonance drive and fine movement by DC drive, a drive system capable of wide-range, high-speed drive and high-accuracy positioning can be realized.

  As a driving method, by applying a DC voltage only to the A-phase electrode 101a, the three-divided region including each vertex of the vibrating body 10 is bent in the CCW direction as shown in FIG. The tip of the chip member 103 falls in the CCW direction. The rotor 20 in frictional contact with the tip member 103 moves (rotates) by the same amount by the frictional force, and returns to the original state when the voltage application is stopped. Similarly, by applying a DC voltage only to the B-phase electrode 101b, the rotor 20 can be moved in a small amount in the CW direction. Further, when a DC voltage is applied to the A-phase electrode 101a, a negative voltage is applied to the B-phase electrode 101b, whereby the bending amount of the vibrating body 10 is increased and the rotation amount of the rotor 20 can be increased.

  Next, an embodiment of a magnetic recording apparatus using the ultrasonic actuator 5 having such a configuration for driving a magnetic recording head will be described.

  An actuator used to drive a magnetic recording head (hereinafter abbreviated as “head”) of a conventional magnetic recording apparatus (hereinafter referred to as “HDD”) is configured to rotatably support an arm to which a head is attached by a pivot bearing. (Voice coil motor) is used for driving. When an HDD head is driven, it is necessary to perform positioning control while following the waviness of a track on a disk rotating at high speed, and the actuator is required to have very high responsiveness and resolution. As the responsiveness increases, the recording density increases, so that the recording capacity of the HDD can be increased.

  However, since the conventional actuator configuration uses a bearing, if the frequency of the oscillating operation is increased, unnecessary vibration caused by the bearing backlash is excited, and the responsiveness can be increased beyond the resonance frequency. There is no problem. By using the ultrasonic actuator 5 according to the present embodiment for driving the head of the HDD, it is possible to cope with such a problem.

  FIG. 6 shows a schematic configuration of the HDD 1A according to the embodiment of the present invention. The HDD 1 </ b> A includes a recording disk (recording medium) 2, an arm 4 rotatably provided in the direction of arrow A (tracking direction) by the ultrasonic actuator 5, a head 3 attached to the tip of the arm 4, and the disk 2. The housing 1 is provided with a motor (not shown) that rotates the head 3 in the direction of arrow B, and the head 3 can move relative to the disk 2.

  As described above, the ultrasonic actuator 5 has a configuration that does not play back and forth while holding the vibrating body 10 by the elasticity of the rotor 20, and can hold the rotor 20 at each vertex of the equilateral triangle of the vibrating body 10. So the holding stability is very high. Therefore, the resonance frequency of the ultrasonic actuator 5 can be increased, and very high responsiveness can be obtained as compared with the conventional case.

  The recording area on the disk 2 is about 30 ° as the driving angle of the arm 4, and the waviness of the track is several nm to several tens of μm. High response positioning is required. The ultrasonic actuator 5 according to the present embodiment can meet these requirements by combining the coarse movement by the resonance drive and the fine movement by the DC drive, and further has a very simple configuration. Increase the manufacturing cost.

[Embodiment 2]
A vibrating body 10 according to Embodiment 2 is shown in FIG. 7A is a front view showing the configuration of the vibrator 10 according to the second embodiment, FIG. 7B is a side view, FIG. 7C is the first internal electrode layer 101n1, and FIG. 7D. These are figures which show the structure of the 2nd internal electrode layer 101n2.

  The piezoelectric member 101 according to the first embodiment is a single piezoelectric ceramic as described above, but in the case of the second embodiment, it has a laminated structure.

  As shown in FIG. 7B, the piezoelectric member 101 includes piezoelectric ceramic thin plates (hereinafter referred to as piezoelectric thin plates) 101h, first internal electrode layers 101n1, and second internal electrode layers 101n2 that are alternately stacked. As shown in FIG. 7C and FIG. 7D, the first internal electrode layer 101n1 and the second internal electrode layer 101n2 are each apex of the vibrator 10 as in the case of the drive electrode in the first embodiment. The shape is divided by each perpendicular line extending from the side to the opposite side (six divisions), each vertex has a pair of A-phase electrode region and B-phase electrode region, and an A-phase electrode 101a and a B-phase electrode 101b are provided respectively. It has been.

  As shown in FIG. 7B, external electrodes 101ga and 101gb are provided on the side surface of the vibrating body 10 and connected to the internal electrodes (A-phase electrode 101a and B-phase electrode 101b) protruding from the end surface. The internal electrodes are commonly connected every other layer. In this case, the external electrodes 101ga and 1010gb on the side surfaces are connected to the drive signal generation unit using lead wires or the like.

  Since the piezoelectric member 101 according to the second embodiment has a laminated structure, the same amplitude can be obtained at a lower voltage as compared with the case of the first embodiment. Therefore, a booster circuit or the like is not necessary, the drive circuit is simplified, and it is suitable for application to battery-driven devices such as portable devices. The driving method is the same as in the first embodiment.

[Embodiment 3]
A vibrating body 10 according to Embodiment 3 is shown in FIG. 8A is a front view showing the configuration of the vibrating body 10 according to the third embodiment, FIG. 8B is a side view, and FIG. 8C is a back view.

  As shown in FIG. 8B, the vibrating body 10 according to the third embodiment has a configuration in which a piezoelectric thin plate 101h is attached to both surfaces of a thin plate-like vibration plate 101s.

  The diaphragm 101s is made of metal. The piezoelectric thin plate 101h is attached to the vibration plate 101s using a conductive adhesive, thereby being electrically connected to the metal vibration plate 101s, and the vibration plate 101s can be used as a common electrode (GND electrode). The driving electrodes (A-phase electrode 101a and B-phase electrode 101b) are formed on the other surface of the piezoelectric thin plate 101h as in the case of the first embodiment. The FPC 30 (not shown) is connected to a fixing member 40 that is electrically connected through two driving electrodes and a fixing pin 401 (not shown) that holds the vibrating body 10. In such a configuration, it is not necessary to newly provide a tip member, and the tip member can also be used by applying a wear-resistant material or surface treatment to the metal diaphragm 101s. As the material of the vibration plate 101s, stainless steel that is inexpensive and easy to manufacture and subjected to surface hardening treatment such as nitriding treatment, cemented carbide, or the like is used.

  In the case of the third embodiment, the vibration plate 101s resonates due to the excitation force of the piezoelectric thin plate 101h, so that elliptical vibration is generated at each vertex of the vibrating body 10. Usually, since the Q value of metal is higher than that of piezoelectric ceramics, loss during vibration is small, and heat generation of the vibrating body 10 can be suppressed, and driving efficiency can be increased. In addition, since the piezoelectric member 101 can be made relatively thin and the volume of the piezoelectric member 101 can be made relatively small, the cost can be reduced, which is suitable for application to a portable device or the like.

[Embodiment 4]
FIG. 9 shows a vibrating body 10 according to the fourth embodiment. FIG. 9A is a front view showing the configuration of the vibrating body 10 according to the fourth embodiment, FIG. 9B and FIG. 9D are side views, and FIG. 9C is a bottom view.

  As shown in FIG. 9A, the vibrating body 10 according to the fourth embodiment has a configuration in which a piezoelectric thin plate 101 h is attached to each side of the metal elastic body 105. The piezoelectric thin plate 101h on each side is divided into two, and the driving electrodes (A-phase electrode 101a and B-phase electrode 101b) are provided at each vertex as in the case of the first to third embodiments. The piezoelectric thin plate 101h is attached to the metal elastic body 105 using a conductive adhesive, thereby being electrically connected to the metal elastic body 105, and the metal elastic body 105 can be used as a common electrode (GND electrode). In this case, the vibrating body 10 is provided with a through hole 10 a at the center of gravity and is fixed to the fixing member 40 via a fixing pin 401 (not shown).

  As the material of the metal elastic body 105, as in the case of the third embodiment, stainless steel subjected to surface hardening treatment such as nitriding treatment, cemented carbide or the like is used.

  As in the case of the third embodiment, the metal elastic body 105 resonates due to the excitation force of the piezoelectric thin plate 101 h, thereby causing elliptical vibration at each vertex of the vibrating body 10. Also in this case, since the loss during vibration is small, the heat generation of the vibrating body can be suppressed and the driving efficiency can be increased.

[Embodiment 5]
A vibrating body 10 according to Embodiment 5 is shown in FIG. FIG. 10A is a front view showing the configuration of the vibrator 10 according to the fifth embodiment, FIG. 10B is a side view, and FIG. 10C is a back view.

  As shown in FIG. 10A, the vibrating body 10 according to the fifth embodiment is a modification of the first embodiment, and is formed in a constricted shape near the center of each side of the vibrating body 10. By adopting such a shape, the bending vibration mode is easily excited, and the amplitude in the tangential direction T can be increased.

1 is an overall configuration diagram of an ultrasonic actuator according to Embodiment 1 of the present invention. 6 is a diagram illustrating a method for fixing a vibrating body according to the first embodiment. FIG. 3 is a diagram illustrating a configuration of a vibrating body according to Embodiment 1. FIG. FIG. 6 is a diagram illustrating a state of deformation in the natural mode of the vibrator according to the first embodiment. It is a schematic diagram which shows the mode of a change of the elliptical locus with respect to the phase difference of a drive signal. 1 is an overall configuration diagram showing an outline of a magnetic recording apparatus according to an embodiment of the present invention. It is a figure which shows the structure of the vibrating body by Embodiment 2 of this invention. It is a figure which shows the structure of the vibrating body by Embodiment 3 of this invention. It is a figure which shows the structure of the vibrating body by Embodiment 4 of this invention. It is a figure which shows the structure of the vibrating body by Embodiment 5 of this invention. FIG. 6 is a diagram illustrating a state of deformation in an eigenmode according to another example of the vibrator according to the first embodiment. It is a block diagram which shows an example of a drive signal generation part. It is a figure which shows an example of a drive signal. It is a block diagram which shows another example of a drive signal generation part. It is a figure which shows another example of a drive signal.

Explanation of symbols

1A Magnetic recording device (HDD)
DESCRIPTION OF SYMBOLS 1 Case 2 Disk 3 Head 4 Arm 5 Ultrasonic actuator 10 Vibrating body 10a Through-hole 10p, 10q, 10r Vertex 101 Piezoelectric member 101a A phase electrode 101b B phase electrode 101c Common electrode 101ga, 101gb External electrode 101h Piezoelectric ceramic thin plate (piezoelectric) Thin film)
101n1 First internal electrode layer 101n2 Second internal electrode layer 101s Vibration plate 103 Chip member 105 Metal elastic body 20 Rotor (moving body)
30 FPC (Flexible Printed Circuit Board)
DESCRIPTION OF SYMBOLS 40 Fixing member 401 Fixing pin 403 Screw 405 Adhesive 7 Drive signal production | generation part 71 Control part 72 Oscillation part 73 Phase change part 74 Amplification part 75 Speed detection part

Claims (8)

A substantially triangular vibrating body having a piezoelectric displacement portion that expands and contracts by a drive signal;
A movable body that is in pressure contact with the three vertices of the vibrating body and generates a relative movement with respect to the vibrating body;
The vibrator is
Expansion and contraction due to expansion and contraction of the piezoelectric displacement part,
One of the vertexes is a stretching vibration mode in which the vertex reciprocates in a direction connecting the vertex and the center of gravity of the vibrating body;
Bending and deforming due to expansion and contraction of the piezoelectric displacement part,
One of the apexes has a bending vibration mode that reciprocates in a direction perpendicular to the direction of the reciprocating movement by the stretching vibration mode,
The moving body is
The stretching vibration mode and the bending vibration mode are resonantly excited, and the three vertices of the vibrating body perform elliptical vibration in the same rotational direction, thereby causing relative movement with respect to the vibrating body. Ultrasonic actuator. The superposition according to claim 1, wherein the piezoelectric displacement portion has a pair of A-phase electrodes and B-phase electrodes to which the drive signals are supplied, corresponding to the three apexes of the vibrating body. Sonic actuator. A drive signal generator for generating the drive signal;
The resonance frequency of the stretching vibration mode and the bending vibration mode are the same value,
The drive signal generation unit generates two-phase AC voltages having frequencies close to the resonance frequency and different phases, and supplies the two-phase AC voltages to the A-phase electrode and the B-phase electrode, respectively. The ultrasonic actuator as described in. The ultrasonic actuator according to claim 1, wherein the vibrating body has an equilateral triangle shape. The moving body has a cylindrical shape and performs a rotational motion with respect to the vibrating body,
The cylindrical inner peripheral surface of the movable body circumscribes the three apexes of the vibrating body, and is in pressure contact with the three apexes of the vibrating body by the elastic force of the moving body. Item 5. The ultrasonic actuator according to any one of Items 1 to 4. The ultrasonic actuator according to claim 1, wherein the vibrating body is held and fixed by a holding member in the vicinity of the center of each of the three sides of the vibrating body. The ultrasonic actuator according to claim 1, wherein the vibrating body is held and fixed by a holding member in the vicinity of the center of gravity of the vibrating body. A recording medium for recording information;
A magnetic head for reading and writing the information on the recording medium;
An arm that supports the magnetic head to be movable relative to the recording medium;
An ultrasonic actuator according to any one of claims 1 to 7,
The magnetic recording apparatus according to claim 1, wherein the arm is fixed to the moving body provided in the ultrasonic actuator.

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