JP3041052B2 - Recording / reproducing head, recording / reproducing head positioning mechanism, and recording / reproducing device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a recording / reproducing head, a recording / reproducing head positioning mechanism, and a recording / reproducing device such as a magnetic disk device and an optical disk device.

BACKGROUND ART FIG. 32 shows a plan view of a floating magnetic head used in a conventional magnetic disk drive (HDD) and a positioning mechanism thereof.

Referring to FIG. 1, the magnetic head includes a slider 2 on which an electromagnetic transducer 1 is formed, and a suspension 3 supporting the slider 2. The wiring for electrically connecting the electromagnetic transducer 1 and the signal processing circuit of the magnetic disk drive to transmit the recording / reproducing signal is not shown.

Actuators for positioning the magnetic head include:
A VCM (voice coil motor) 5 is used. VCM5
Is a coil 51, a permanent magnet 52, a bearing 53 and an arm
The arm 54 has a coil 51 attached to one end and a suspension 3 of the magnetic head attached to the other end. A permanent magnet (not shown) is also provided above the coil 51.

The electromagnetic conversion element 1 has a magnetic pole and a coil for mutually converting an electric signal and a magnetic signal, and in addition to these, a magnetoresistive element for converting a magnetic signal into a current change, and the like. Are formed by a thin film forming technique, an assembly processing technique, or the like. Slider 2 is made of Al ₂ O ₃ -T
It is composed of a magnetic material such as nonmagnetic ceramics such as iC or CaTiO ₃ or ferrite, and has a substantially rectangular parallelepiped shape, and a surface facing the disk medium 6 (air bearing surface).
Is processed into a shape suitable for generating a pressure for floating the disk medium 6 at a minute distance. The suspension 3 is formed by subjecting an elastic stainless steel plate or the like to processing such as bending or punching.

Next, the operation at the time of recording and reproduction will be described. Since the disk medium 6 is rotating at a high speed of about several thousand revolutions per minute,
Air flows between this and the slider 2 and the slider 2
Is subjected to a floating force. On the other hand, since the slider 2 is pressed against the disk medium 6 with a predetermined load by the suspension 3, the slider 2 floats on the disk medium 6 at a small distance based on the relationship between the floating force and the pressing force. .

Since the magnetic head is connected to VCM5, the bearing
The rocking movement around the center 53 enables the disk medium 6 to move in the radial direction, and controls the positioning of the electromagnetic transducer 1, that is, seek control for moving to an arbitrary recording / reproducing track and recording / reproducing track. Following control is performed.

The positioning control of the magnetic transducer 1 is performed by detecting the track position signal recorded on the disk medium 6 by the electromagnetic transducer 1, and the drive signal processed by the head positioning control circuit 7 is supplied to the coil 51 of the VCM 5 via the amplifier 8. This is performed by flowing a predetermined current and controlling a force generated between the permanent magnet 52 and the magnet. The electromagnetic transducer 1 positioned on the target track records and reproduces a magnetic signal on the disk medium 6.

As described above, conventionally, VCM has generally been used as a means for positioning a magnetic head.

In magnetic disk drives, synchronous or asynchronous disk medium surface vibrations accompanying rotation of the disk medium, eccentricity of the disk medium, thermal expansion and disturbance vibrations of the magnetic disk device including the magnetic head and the disk medium, and the like, cause the magnetic head and the recording track to be separated from each other. Position shift occurs between the two. For this reason, the signal information of the adjacent track is erased by overwriting at the time of recording, the reproduction signal level of the target track is reduced at the time of reproduction, or the signal of the adjacent track is mixed as crosstalk noise and the quality of the reproduction signal is reduced. Or decrease.

Therefore, at the time of recording / reproducing, it is necessary to make the position of the electromagnetic transducer of the magnetic head accurately and quickly follow a predetermined recording track on the disk medium.

However, the above-described conventional magnetic disk drive has a configuration in which the entire large-mass structure including the magnetic head, the arm, and the coil is swung, and a configuration in which the slider is moved via an elastic suspension.
In addition, there is a problem that the positioning accuracy, particularly the tracking accuracy of the recording track, is limited because the bearing that is the center of the swing always has friction resistance, eccentricity, and the like.

On the other hand, there is a strong demand for high-density recording in magnetic disk devices, and as a result, the track density is higher, that is, the recording track width is becoming narrower. Accordingly, it is necessary to improve the positioning accuracy of the magnetic head. ing. The conventional positioning control band is about 500 Hz, the positioning accuracy is about 0.3 μm, but the recording track width is 1 μm.
When it is narrowed to a degree, the control band is several kilohertz,
A positioning accuracy of about 0.1 μm is required. For this reason, the problem in the conventional magnetic head positioning mechanism has become more apparent.

Conventionally, the flying height of the magnetic head is generally 50 to 100 n.
However, if the recording / reproducing track pitch is reduced to about 1 μm while keeping the flying height at this level, the signal information of the adjacent track is erased by the recording leakage magnetic field during recording, or the signal level is absolutely output during reproduction. Due to the decline
Various issues such as deterioration of S / N come out. Therefore, to maintain stable recording / reproducing characteristics, the flying height of the magnetic head with respect to the disk medium needs to be 50 nm or less. However, when the flying height is reduced, it is necessary to more strictly manage the flying characteristics (floating amount fluctuation) during the seek control or the recording / reproducing track following control and the smoothness of the disk medium.

By the way, recently, researches on a magnetic head called a pseudo contact type head having an extremely small flying height and a contact type head in which the magnetic head and the disk medium are always in contact have been advanced.
Since the purpose of using these magnetic heads is to further increase the recording density, seek control and recording / reproducing track follow-up control become more difficult with these magnetic heads.

As one of methods for improving the positioning accuracy of a magnetic head, a method of providing a small displacement actuator such as a piezoelectric element on a magnetic head mounting arm or a support spring (suspension) has been proposed (Japanese Patent Laid-Open No. 5-28670,
No. 5-47126). Although these methods improve the positioning accuracy of the magnetic head to some extent, these methods are also similar to the positioning mechanism using the VCM in that the slider is driven through the elastic suspension, so that they are not affected by the vibration of the suspension. Cannot be performed, and there is a limit in improving the positioning accuracy.

In addition, a method using a small electrostatic force actuator to displace the slider (Magnetic Recording Head)
Positioning at Very High Track Densities Using a M
icroactuator-Based, Two-Stage Servo System, IEEE T
RANSACTIONS ON INDUSTRIAL ELECTLONICS, VOL.42, NO.3,
pp.222-233, JUNE 1995) and a method using a small electromagnetic force actuator (Silicon Microstructures and Micr)
oactuators for Compact Computer Disk Drives, IEEE C
ONTROL SYSTEMS, pp.52-57, DECEMBER 1994), however, it is difficult for an electrostatic force actuator to generate a driving force enough to displace a slider, and an electromagnetic force actuator uses a disk due to leakage magnetic flux. There is a problem that the magnetic signal of the medium may be affected. In both cases, the slider must be held by a small elastic supporting member that can be deformed by an electrostatic force or an electromagnetic force generated by the actuator, and thus there is a problem that the slider is vulnerable to disturbance. The driving of the slider by the electrostatic actuator is also described in Japanese Patent Application Laid-Open No. 8-180623, but the same problem occurs with this device.

Japanese Patent Application Laid-Open No. 6-259905 discloses a configuration in which a slider provided with a recording / reproducing function section (electromagnetic transducer) and a suspension driven by a VCM are connected via a driving member such as a piezoelectric element. An actuator for a recording / reproducing device is described. First embodiment of the publication (see FIG. 1)
The thin fine movement mechanism (driving member) in the above is composed of a pair of opposed thin plates and a set of piezoelectric elements, and one end of each end of each piezoelectric element is connected to both ends of each thin plate. A bent portion is provided on a diagonal line, and each end of the piezoelectric element is connected to the bent portion. In this thin type fine movement mechanism, the recording / reproducing function can be minutely displaced in a direction almost perpendicular to the direction of expansion and contraction of the piezoelectric element by deforming the piezoelectric element so as to expand or contract together. It has become. Further, the thin fine movement mechanism in the second embodiment (see FIG. 2) of the publication is composed of a pair of opposed thin plates and a pair of piezoelectric elements as in the first embodiment. However, this embodiment differs from the first embodiment in that a bent portion for connecting one end of each piezoelectric element is provided at one end of each thin plate. In this thin type fine movement mechanism,
By bending each piezoelectric element in the same direction in a plane parallel to the flying surface of the slider, the recording / reproducing function unit similar to that in the first embodiment can be slightly displaced. Further, in the third embodiment (see FIG. 3) of the publication, the fine movement mechanism section is constituted only by a set of piezoelectric elements which can be flexibly deformed. That is, each piezoelectric element has a slider connected to one end and a suspension connected to the other end.

In this publication, as a prior art, a fine actuator in which a piezoelectric element is embedded freely in a slider is mentioned. In such a slider (fine actuator), deformation such as torsion or distortion occurs on the air bearing surface, which affects the flying characteristics. Trying to give. In the thin type fine movement mechanism, since no stress is applied to the slider, the slider is not deformed and the actuator which does not affect the flying behavior of the head can be constituted. I have. However, since the thin fine movement mechanism of the first embodiment and the second embodiment has an assembly structure in which a pair of thin plates are connected by a pair of piezoelectric elements, even if there is no characteristic difference between the two piezoelectric elements. In addition, blurring in the flying direction (floating amount fluctuation) is likely to occur due to an assembly error or the like. Further, since an assembling process is required, the cost increases. In addition, in the assembly structure, it is difficult to increase rigidity, mechanical durability of an adhesive portion and the like is lowered, and it is necessary to draw a wiring from an electrode of the piezoelectric element.
There is also a problem that the structure becomes complicated and the structure cost increases. Similarly, the third embodiment also has a problem that an assembly error causes variation in displacement characteristics.

The actuator described in FIG. 6 of the same publication as the prior art and the actuator described in FIG. 5 of the above-mentioned Japanese Patent Application Laid-Open No. 5-28670 have a structure in which a displacement generating element such as a piezoelectric element is fitted in a suspension. Therefore, it is difficult to manage the tolerance between the size of the displacement generating element and the size of the gap into which the displacement generating element is fitted. Since the amount of displacement of the piezoelectric element is very small, if there is a gap between the two, loss or variation occurs in the transmitted displacement, and the displacement may not be transmitted at all. Therefore, it is necessary to assemble with high precision so as not to form a gap, which involves technical difficulties and increases costs.

JP-A-63-291271 describes a magnetic head positioning mechanism provided with a fine movement mechanism comprising a piezoelectric element or an electrostrictive element between a slider and a load bar. The fine movement mechanism described in the example of the publication has a thin U-shaped notch formed in a thin piezoelectric element plate, and a part of the piezoelectric element plate is expanded and contracted to have the same direction as the expansion and contraction. To linearly displace the slider. This fine movement mechanism is not an assembly structure but an integral type, but since the displacement of the slider depends on the linear displacement of the piezoelectric element plate, the size of the fine movement mechanism must be increased in order to increase the displacement of the slider. There is a problem that must be done.

In the configuration described in FIGS. 1 to 4 in JP-A-5-47126, the sheet-shaped piezoelectric element itself is adhered to the head supporting spring, so that the head supporting spring impedes the displacement of the piezoelectric element. Becomes For this reason, the small displacement of the piezoelectric element is further reduced. In addition, since a load is applied to the piezoelectric element, the service life is shortened, the characteristics deteriorate quickly, and sufficient durability cannot be obtained. In addition, since an adhesive layer made of an organic resin or the like is usually used for attaching the piezoelectric element, the adhesive layer is deformed with the displacement of the piezoelectric element, resulting in transmission loss. Further, when the piezoelectric element is displaced, a load is also applied to the adhesive layer, so that the reliability of the bonding is lowered. Also, since the adhesive force (fixing force) changes and the rigidity of the adhesive layer itself changes depending on the load and environmental conditions (high temperature, high humidity, etc.), the electromagnetic conversion from the piezoelectric element via the adhesive layer is performed. The displacement transmitted to the element changes over time.

FIG. 6 of JP-A-6-309822 shows a configuration in which a sheet-like piezoelectric element is mounted on a pair of thin metal plates constituting a parallel leaf spring of a gimbal portion formed at the tip of a suspension. A recording / reproducing head having driving means is recorded. In this driving means, a length difference between the piezoelectric element and the metal thin plate is generated due to expansion and contraction of the piezoelectric element, and the electromagnetic transducer is displaced by bending of the two. Also in this configuration, since the piezoelectric element bends the metal sheet via the adhesive layer, a load is also applied to the adhesive layer, and the reliability is reduced.

Japanese Patent Application Laid-Open No. 60-47271 describes a floating head provided with a drive element for finely moving the head main body in the direction parallel to the information track between the slider and the head main body. A piezoelectric element is mentioned as the driving element.
Specifically, there are described one that finely moves the head main body by using a change in the thickness of the laminated piezoelectric element and one that uses a bimorph type piezoelectric element. The head body described in the publication is not a thin film head electromagnetic transducer, but a normal bulk type magnetic head. The multilayer piezoelectric element described in the publication uses a displacement in the same direction as the electric field, that is, a piezoelectric longitudinal effect, and linearly displaces the head body using a linear displacement in the thickness direction due to the displacement. There is a problem that the size of the piezoelectric element must be increased in order to increase the displacement of the main body. Further, in the structure described in the publication, a part of the floating surface is deformed and displaced. For this reason, there arises a problem that the flying characteristics are not stable, and a problem that the recording / reproducing characteristics are not stable due to a variation in spacing between the head body and the medium.

In the above description, the electromagnetic head among the recording / reproducing heads has been described. However, the above-described problems concerning the positioning of the magnetic head similarly occur in the recording / reproducing head for an optical disk device. In a conventional optical disk device,
An optical pickup provided with an optical module having at least a lens is used. In this optical pickup, the lens is mechanically controlled so that the recording surface of the optical disc is focused. However, recently, near-field recording has been proposed as a method for dramatically increasing the recording density of optical disks [NIKKEI ELECTRONICS 1997.6.16
(No.691), p.99], in this near-field record,
A floating head is used. This flying type head uses a slider similar to the flying type magnetic head,
It incorporates an optical module having a hemispherical lens called L (solid immersion lens), a magnetic field modulation recording coil, and a prefocus lens. A flying head for near-field recording is disclosed in U.S. Pat.
It is also described in the specification of 7,359. An optical disk used in combination with such a flying head has an extremely high recording track density, and thus poses the above-described problems similar to those of the flying magnetic head when positioning with respect to the recording tracks.

DISCLOSURE OF THE INVENTION An object of the present invention is to enable a magnetic disk device to perform high-accuracy and high-speed positioning of an electromagnetic transducer or an optical module provided in a recording / reproducing head in a recording / reproducing device such as an optical disk device. In addition, when performing such positioning, it is to suppress a change in position of the electromagnetic transducer or the optical module in a direction perpendicular to the surface of the recording medium by a simple method.

Such an object is achieved by any one of the following configurations (1) to (17).

(1) A slider provided with an electromagnetic transducer or an optical module, an actuator, and a suspension. The slider is supported by the suspension via the actuator. And a displacement generating part is formed in at least one of the beam parts, and the displacement generating part expands and contracts in a direction connecting the fixed part and the movable part by an inverse piezoelectric effect or an electrostrictive effect. The fixed part is fixed to the suspension and the movable part is fixed to the slider, respectively, and as the displacement generating part expands and contracts, it flexes to the displacement generating part and the movable part moves linearly or arcuately with respect to the fixed part, or rotational displacement. And draw a linear or arc-shaped locus so that the electromagnetic transducer or the optical module intersects the recording track of the recording medium. The fixed part, the movable part, and the beam part are integrally formed by providing a hole and / or a notch in a plate made of a piezoelectric / electrostrictive material. Recording / playback head.

(2) The recording / reproducing head according to (1), wherein the actuator is disposed on the back surface or the side surface of the slider.

(3) The recording / reproducing head according to (2), wherein the actuator is disposed in a space formed by a step provided on the back surface of the slider.

(4) The recording / reproducing head according to any one of (1) to (3), wherein the slider and the actuator are arranged to face each other across the suspension.

(5) A gimbal portion for causing the slider to follow the recording medium surface is provided in a part of the suspension.
The recording / reproducing head according to any one of (1) to (4), wherein an actuator is connected to the gimbal portion.

(6) The recording / reproducing head according to any one of (1) to (5), wherein at least two piezoelectric / electrostrictive material layers having electrode layers on both sides are present in the displacement generating portion of the actuator.

(7) The recording / reproducing head according to any one of (1) to (6), wherein an amount of displacement of the electromagnetic transducer or the optical module is larger than an amount of expansion and contraction of a displacement generating portion of the actuator.

(8) The recording / reproducing head according to (7), wherein a displacement of the electromagnetic transducer or the optical module is larger than a displacement of a connecting portion between the slider and the actuator.

(9) The recording / reproducing head according to (7) or (8), wherein an amount of displacement of a connecting portion between the slider and the actuator is larger than an amount of expansion and contraction of a displacement generating portion of the actuator.

(10) The recording / reproducing head according to any one of (1) to (9), wherein wiring to the actuator and / or the electromagnetic transducer or the optical module is formed on the suspension.

(11) A recording / reproducing head positioning mechanism having the recording / reproducing head according to any one of (1) to (10) and a main actuator for driving the entire recording / reproducing head.

(12) A mechanism that has a slider provided with an electromagnetic transducer or an optical module, an actuator, and a suspension, and the slider positions a recording / reproducing head supported by the suspension via the actuator, and the actuator is fixed. A movable portion and at least two beam portions connecting the movable portion and the movable portion, and at least two of the beam portions are formed with a displacement generating portion, and the displacement generating portion is connected to the fixed portion by an inverse piezoelectric effect or an electrostrictive effect. The movable part is fixed to the suspension, the movable part is fixed to the slider, and the movable part becomes flexible as the displacement generating part flexes as the displacement generating part expands and contracts. On the other hand, by linear displacement, arc displacement or rotational displacement, the electromagnetic conversion element or the optical module causes the recording track of the recording medium to move. It is intended to displace draw a straight or arcuate path so as to intersect, when performing positioning in the direction orthogonal to the recording tracks,
A recording / reproducing head positioning mechanism for controlling the sum of the driving voltages applied to the respective displacement generating parts so as to be constant at any time.

(13) The direction of expansion and contraction of each displacement generating section is the same for an applied voltage of the same polarity, and the voltage applied to each displacement generating section is obtained by adding a control voltage to a DC bias voltage. (12) The recording / reproducing head positioning mechanism according to (12), wherein the total sum of the control voltages added in the displacement generating section is controlled to be zero at any time.

(14) each of the displacement generating sections includes a displacement section that expands and contracts by applying a voltage, and a pair of cover sections that sandwich the displacement section;
The displacement portion and the cover portion are stacked in a direction perpendicular to the surface of the recording medium, and the cover portion is in close contact with the displacement portion and is deformed as the displacement portion expands and contracts (12) or (13) The recording / reproducing head positioning mechanism.

(15) The recording / reproducing head positioning mechanism according to any one of (12) to (14), wherein the recording / reproducing head is any one of (1) to (10).

(16) The recording / reproducing head positioning mechanism according to any one of (12) to (15), further comprising a main actuator for driving the entire recording / reproducing head.

(17) A recording / reproducing apparatus having the recording / reproducing head of any one of (1) to (10) or the recording / reproducing head positioning mechanism of any of (11) to (16).

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view for explaining a basic configuration example of a magnetic head of the present invention and a positioning mechanism of an electromagnetic transducer, and FIG. FIG. 3 is a perspective view showing a configuration example in which an actuator is arranged on the rear surface of the slider, and FIG. 3 is a perspective view showing a configuration example in which an actuator is arranged on the rear surface of the slider. FIG. 5 is a perspective view showing a configuration example in which an actuator is arranged on the back surface of a slider in the magnetic head. FIG. 5 is a perspective view showing a configuration example in which an actuator is arranged on the back surface of the slider in the magnetic head of the present invention. 6 is a plan view showing a configuration example of an actuator in the magnetic head of the present invention, and FIG. 7A shows exaggerated bending of each part when the movable part of the actuator shown in FIG. 6 is linearly displaced. FIG. 7B is a plan view showing exaggerated bending of each part when the movable part of the actuator shown in FIG. 6 is rotationally displaced, and FIG. 8 is a configuration of the actuator in the magnetic head of the present invention. FIG. 9 is a plan view showing an example of a configuration of an actuator in the magnetic head of the present invention. FIG. 10 is a plan view showing a configuration example of an actuator in the magnetic head of the present invention. FIG. 11 is a perspective view showing a configuration example in which an actuator is disposed on a side surface of a slider in the magnetic head of the present invention. FIG. 12 is a perspective view showing a configuration example in which an actuator is disposed on a side surface of the slider in the magnetic head of the present invention. FIG. 13 is a side view showing a configuration example in which an actuator is arranged on a side surface of a slider in the magnetic head of the present invention, and FIG. 14 is a side view of the magnetic head of the present invention. FIG. 15 is a perspective view showing a configuration example in which an actuator is disposed in a space formed by a step provided on the slider rear surface. FIG. 15 is a perspective view showing an actuator in a space formed by a step provided on the slider rear surface in the magnetic head of the present invention. FIG. 16 is a perspective view showing a configuration example in which a slider and an actuator of the magnetic head of the present invention are arranged to face each other across a suspension, and FIG. FIG. 18A is a side view showing a configuration example of connecting the actuator and the suspension near the center of gravity of the structure including the slider and the actuator in the magnetic head of the present invention.
FIG. 2 is a plan view of a configuration example in which a slider is connected to a gimbal portion of a suspension in the magnetic head of the present invention.
18B is a side view of the magnetic head of the present invention, FIG. 19A is a plan view of a configuration example in which a slider is connected to a gimbal portion of a suspension of the present invention, and FIG. 19B is a side view thereof. FIG. 20B is a plan view of a configuration example in which a slider is connected to a gimbal portion of a suspension in the magnetic head of the present invention. FIG. 20B is a side view thereof, and FIG. FIG. 22A is a perspective view showing a configuration example in which the actuator and the slider are connected with the gimbal portion interposed therebetween. FIG. 22A is a perspective view of the magnetic head of the present invention. FIG. 3 is a plan view of a configuration example that can increase
FIG.22B is a side view of the magnetic head, and FIG.23A is a plan view of a configuration example of the magnetic head according to the present invention in which the displacement of the electromagnetic transducer can be larger than the expansion and contraction of the displacement generator of the actuator. 23B is a side view thereof, FIG. 24 is a perspective view showing a configuration example of an actuator used in the magnetic head of the present invention, and FIG. 25A is an exploded perspective view showing a configuration example of an internal electrode layer. FIG. 25B is a plan view illustrating a configuration example of a terminal electrode, and FIG. 26 is a perspective view illustrating a basic configuration of drive control in a magnetic head positioning mechanism.
27 is a cross-sectional view of the actuator, FIG. 28 is a graph showing a temporal change of the X-axis direction displacement of the electromagnetic transducer 1 in FIG. 26, and FIG. FIG.29C is a graph showing a temporal change of the Z-axis direction displacement of the electromagnetic transducer caused by the application of the voltage, and FIG.29B is a graph showing the other change of the actuator. FIG. 4 is a graph showing a temporal change of a voltage applied to a displacement generating unit, and FIG.
29D is the Z of the electromagnetic transducer generated with the application of the voltage.
FIG.29E is a graph showing the temporal change of the axial displacement, and FIG.29E
The voltage shown in FIG.29A is applied to one of the displacement generating portions,
FIG. 30A is a graph showing a temporal change in the Z-axis direction displacement of the electromagnetic transducer when the voltage shown in FIG. 29B is applied to the other displacement generator, and FIG. 30A is applied to one displacement generator of the actuator. FIG. 6 is a graph showing a temporal change of a voltage,
FIG. 30C is a graph showing a temporal change in Z-axis displacement of the electromagnetic transducer caused by the application of the voltage.
FIG. 30D is a graph showing a temporal change of a voltage applied to the other displacement generating unit of the actuator, and FIG. 30D is a graph showing a temporal change of a Z-axis direction displacement of the electromagnetic transducer caused by the application of the voltage. FIG. 30E shows the temporal change in the Z-axis direction displacement of the electromagnetic transducer when the voltage shown in FIG. 30A is applied to one displacement generating unit and the voltage shown in FIG. 30B is applied to the other displacement generating unit. FIG. 31 is a graph showing the change, and FIG.
FIG. 32 is a plan view of an actuator having four displacement generating units, and FIG. 32 is a plan view showing a configuration example of a magnetic head positioning mechanism used in a conventional magnetic disk drive.

BEST MODE FOR CARRYING OUT THE INVENTION The operation and effects of a recording / reproducing head according to the present invention will be described below by taking a magnetic head as an example.

FIG. 1 shows an example of a basic structure of a magnetic head according to the present invention. The actuator 4 is interposed between the slider 2 on which the electromagnetic transducer 1 is formed and the suspension 3 and connects them. The actuator 4 is provided with at least one piezoelectric / electrostrictive material layer having electrode layers on both sides, which serves as a displacement generating section. The displacement generating section generates expansion and contraction by an inverse piezoelectric effect or an electrostrictive effect. Due to the expansion and contraction, the slider 2 is displaced relative to the suspension 3. The slider 2 is connected to the actuator 4 such that the displacement direction of the electromagnetic transducer 1 at this time is in a direction intersecting the recording track, preferably in a direction substantially orthogonal to the recording track. In the actuator 4, expansion and contraction control of the displacement generating section is performed by voltage control based on the track position shift signal, whereby the electromagnetic transducer 1 can follow the recording track.

In such a configuration, the positioning accuracy of the slider due to expansion and contraction of the displacement generating portion of the actuator is 0.1 μm.
It can be shifted as follows. The mass of the slider driven by the actuator is much smaller than the entire magnetic head including the arm, coil and suspension of the conventional positioning mechanism (VCM). The slider to be driven has a spring property. Without having to be considered rigid
The driving force generated by the actuator due to the inverse piezoelectric effect or the electrostriction effect is sufficiently larger than that of an electrostatic force actuator with the same displacement, so that the slider positioning control frequency can be set to several kilohertz or more. The positioning accuracy is greatly improved as compared with a conventional magnetic disk device which performs positioning. Further, there is no concern about the influence on the disk medium due to the leakage magnetic field which is concerned about the electromagnetic force actuator. Further, in the case of an actuator using an electrostatic force or an electromagnetic force, it is necessary to support the movable portion with an elastic member having a relatively low rigidity. Piezo /
Since the electrostrictive ceramics can be used and the actuator and the slider can be connected without the intervention of an elastic member, displacement is unlikely to occur.

As described above, in the magnetic head of the present invention, the conventional method of displacing and positioning the entire magnetic head including the suspension having the spring property by the VCM or the minute displacement actuator such as the piezoelectric element, and the electrostatic force and the electromagnetic force As compared with the conventional method in which the slider is displaced by the actuator using the positioning method, the positioning control frequency can be broadened, and highly accurate track positioning control can be realized.

The actuator used in the present invention is provided with a hole and / or a notch in a plate made of a piezoelectric / electrostrictive material, so that a portion (movable portion and fixed portion) connected to the slider and the suspension can be displaced. The beam portion having the generating portion is integrally formed. Therefore, the rigidity and dimensional accuracy of the actuator can be increased, and there is no fear that an assembly error occurs. In addition, since no adhesive is used in the structure of the actuator itself, there is no adhesive layer in a portion where stress is generated due to the deformation of the displacement generating portion. Therefore, there are problems such as transmission loss due to the adhesive layer and aging of the adhesive strength. Does not occur. Further, in order to form each part integrally, for example, as shown in FIG. 25A and FIG. 25B, the internal electrode layers A ₁ , B ₁ , G ₁ provided in the displacement generation part are extended to the fixing part 43, and It is possible to adopt a configuration that is connected to the terminal electrodes A ₀ , B ₀ , and C _{0 of the} fixed portion 43. In this configuration, it is not necessary to connect a wire or the like to the electrode of the displacement generating unit for driving the actuator. Also, wiring to the slider can be performed via an actuator instead of a wire or the like.
Therefore, the manufacturing is easy and the reliability is high. On the other hand, the actuator (thin type fine movement mechanism) described in Japanese Patent Application Laid-Open No. 6-259905 manufactures a portion corresponding to a fixed portion and a portion corresponding to a movable portion and a portion corresponding to a displacement generating portion independently. Since these are assembled, rigidity, durability, and dimensional accuracy are increased, and an assembly error is inevitably generated. Further, generally, it is necessary to wire a wire to a portion corresponding to the displacement generating portion, so that there is a problem in terms of manufacturing cost and reliability.

The magnetic head of the present invention can be basically realized by adding an actuator to a conventional magnetic head, and the conventional electromagnetic transducer, slider, and suspension can be used as they are, resulting in a significant cost increase. Also does not invite.

Although the amount of displacement generated by the inverse piezoelectric effect and the electrostrictive effect is extremely small, in the present invention, the amount of displacement of the electromagnetic transducer can be made larger than the amount of expansion and contraction of the displacement generating portion and the amount of displacement of the movable portion. That is, the displacement amount can be amplified. Specifically, in the configuration in which the displacement generating portion expands and contracts and flexes, for example, in the actuator shown in FIG. 22A, the displacement amount of the movable portion 44 (the connection portion between the slider and the actuator) is larger than the expansion amount of the displacement generating portion 41. can do. That is, the figure
The actuator shown in FIG. 22A is an example of a configuration having a displacement enlarging function itself. If the displacement of the movable part with respect to the fixed part caused by the expansion and contraction of the displacement generation part is an arc-shaped displacement or a rotational displacement, the structure of the actuator and the connection position between the actuator and the slider should be appropriate. Accordingly, the displacement of the electromagnetic transducer can be larger than the displacement of the movable part. For example, FIG.
In the actuator shown in A, the movable part is displaced in an arc. Therefore, as shown in FIG. 23A, in this actuator, if the distance between the connecting portion between the movable portion 44 and the slider 2 and the electromagnetic transducer 1 is increased, the amount of displacement of the electromagnetic transducer 1 can be reduced. Can be larger than the displacement amount. As described above, according to the present invention, the displacement can be amplified, so that a practically sufficient displacement can be obtained even if the actuator is downsized. On the other hand, in a configuration in which the piezoelectric element is linearly displaced in the same direction as the direction of the expansion and contraction by using the expansion and contraction of the piezoelectric element, the actuator must be increased in size to obtain a practically sufficient amount of displacement.

In the present invention, the displacement generating portion of the actuator is formed by using at least two piezoelectric / electrostrictive material layers having electrode layers on both sides.
If a structure having layers exists, that is, a so-called laminated structure, each piezoelectric / electrostrictive material layer can be thinned, so that the electric field strength when a predetermined drive voltage is applied can be increased. For this reason, the displacement amount can be increased. Alternatively, it is possible to reduce the drive voltage required to generate a predetermined displacement amount.

Next, effects of the specific configuration example of the present invention will be described.

In the present invention, if the actuator 4 is disposed on the back surface of the slider 2 as shown in FIGS. 2 to 5, for example, the back surface of the slider 2 can be used for connection.

In the present invention, if the actuator 4 is disposed on the side surface of the slider 2 as shown in FIGS. 11 to 13, for example, the increase in the thickness of the entire magnetic head due to the provision of the actuator 4 can be suppressed, When the thickness is smaller than the thickness of the slider 2, the thickness of the magnetic head may not be increased at all. Normally, a magnetic disk device has a structure in which a plurality of disk media are stacked with a working space of a magnetic head interposed therebetween. In order to reduce the thickness of the magnetic disk device, it is necessary to reduce the distance between adjacent disk media. Therefore, if the actuator 4 is arranged on the side surface of the slider 2 as shown in the illustrated example,
As a result of suppressing the increase in the thickness of the magnetic head, the thickness of the magnetic disk device is not hindered.

Also, for example, as shown in FIGS. 14 and 15, even if at least one step is provided on the back surface of the slider 2 and the actuator 4 is arranged in the space 21 formed by the step, the increase in the thickness of the magnetic head is suppressed. be able to. Moreover, in this case, the mass of the slider 2 to be driven is reduced, so that the control band can be expanded.

If the slider 2 and the actuator 4 are arranged to face each other with the suspension 3 interposed therebetween, as shown in FIGS. 16 to 17, for example, the slider exists on one side of the suspension in the conventional magnetic head. And the imbalance due to the absence of anything on the other side is improved. Therefore, when the entire magnetic head is swung by the VCM or the like, the torsion of the suspension is reduced, and the attitude of the slider is stabilized. In particular, if the structure composed of the slider 2 and the actuator 4 is configured so that the mass distribution above and below the suspension 3 is approximately 1: 1,
If the suspension 3 or its extension is configured to pass near the center of gravity of the structure, the imbalance will improve the suspension.

Also, as shown in FIGS. 18A, 19A, 20A, and 21, for example, when the suspension 3 is provided with a gimbal (return spring) for causing the slider 2 to follow the deflection of the surface of the disk medium, the actuator 4 is attached to the gimbal. Is connected, the actuator 4 and the slider 2 can integrally follow the disk medium, and the gimbal mechanism can function effectively. In addition, since force due to torsion of the gimbal portion at the time of following is not applied to the actuator, a decrease in actuator performance is prevented and reliability is improved.

When the present invention is applied to a normal magnetic disk drive, a configuration is generally used in which a conventional magnetic head positioning control function, such as VCM, is used as a main actuator, and an actuator provided in the magnetic head of the present invention is used as a sub-actuator. . That is, usually, the VCM mainly performs the seek operation, and the actuator connected to the slider mainly performs the track following operation, so that the positioning accuracy is improved. Further, in an electrostatic force actuator or an electromagnetic force actuator which needs to support the slider by an elastic member, a track position shift due to a residual vibration after a seek operation or an external shock or vibration is likely to occur. Since the slider and the slider are connected without interposing an elastic member, and the entire actuator is made of a highly rigid piezoelectric / electrostrictive ceramic material, the positional displacement of the track hardly occurs.

As described above, the magnetic head of the present invention and a device in which the magnetic head is combined with a conventional positioning device such as a VCM can perform high-precision and high-speed positioning, so that the recording track width of the disk medium can be reduced, Track density can be improved. Therefore, the recording density of the disk medium can be increased, and the recording capacity of the magnetic disk device can be increased. Further, the access time of the magnetic disk device can be reduced.

In the present invention, the skew angle of the slider can be controlled in the configuration in which the slider on which the electromagnetic transducer is formed is displaced in an arc or in a rotational manner. As can be seen from FIG. 32, since the angle formed by the slider center line and the slider running direction (recording track extending direction) differs between the inner circumferential side and the outer circumferential side of the disk medium 6, the pressure on the air bearing surface of the slider is reduced. The occurrence state is different, and as a result, the flying characteristics of the slider fluctuate. Also,
Since the angle between the electromagnetic transducer and the recording track also fluctuates due to the angle fluctuation of the slider, the recording / reproducing track width also fluctuates. On the other hand, the change in the angle of the slider with respect to the recording track is suppressed by causing the actuator to perform an arc-shaped or rotational displacement of the slider,
Preferably, if the angle is kept constant, fluctuations in the flying characteristics and fluctuations in the recording / reproducing track width can be suppressed.

When the present invention is applied to a magnetic head, the present invention is not limited to a magnetic disk device, but a magnetic recording / reproducing device having a configuration not using a coarse motion actuator such as a VCM, for example, a fixed head type or a rotary head type magnetic tape recording / reproducing device. The present invention is also applicable to other magnetic recording medium recording / reproducing devices.

Next, a preferred control method for driving a magnetic head having an actuator will be described.

In FIG. 1, the positioning control of the electromagnetic transducer 1 is performed as follows. First, the electromagnetic conversion element 1 detects a track position signal recorded on the disk medium 6. Next, a drive current for coarse movement and a drive voltage for fine movement are generated from the track position signal by the head positioning control circuit 7 and the amplifier 8. Then, the positioning control of the electromagnetic conversion element 1 is performed by applying the drive current for coarse movement to the VCM and the drive voltage for fine movement to the displacement generating section of the actuator 4.

In the actuator used in the present invention, since the fixed portion, the displacement generating portion and the movable portion are integrally formed, no assembly error occurs. If there is an asymmetry of the direction,
When controlling the expansion / contraction of the displacement generating portion of the actuator 4 based on the track position signal, the electromagnetic transducer 1 is also displaced in a direction approaching or moving away from the disk medium 6, and a floating amount of the electromagnetic transducer 1 with respect to the disk medium 6. May fluctuate. This variation causes a variation in the level of the reproduced signal, deteriorating the error rate of the read information. In addition, when the variation width is large, a serious problem such as a head crash caused by contact between the magnetic head and the disk medium is caused.

In order not to displace the displacement generator in directions other than the intended direction, it is necessary to strictly control the symmetry of the shape of the displacement generator, the homogeneity of the displacement generator, etc. If performed, there is a problem that the mass productivity is reduced and the cost is increased.

The magnetic head positioning mechanism of the present invention makes it possible to suppress the fluctuation of the flying height caused by the shape asymmetry or inhomogeneity of the displacement generating portion in the flying direction by controlling the drive voltage applied to the actuator. Things. Specifically, when performing the expansion / contraction control of the displacement generating section, the positioning control circuit 7 controls the applied voltage by performing arithmetic processing so that the sum of the voltages applied to each displacement generating section is constant at any time. I do. As a result, it is possible to suppress fluctuations in the flying height when the actuator is driven. Therefore, even if there is asymmetry or inhomogeneity in the displacement generating section, it is possible to suppress the level fluctuation of the reproduction signal and the danger of head crash caused by the contact between the magnetic head and the disk medium, and the stable Highly accurate track positioning control can be realized. As a result, the flying height can be set small, and the recording / reproducing track width of the disk medium can be reduced. Therefore, the track density can be improved, and the recording density of the disk medium can be increased.

Further, the method of controlling the drive voltage applied to the actuator as described above is also effective in the above-described pseudo contact type head and contact type head. These heads have
A load in the direction toward the medium surface is applied so as to have a constant contact pressure.However, a factor that causes a flying height fluctuation in the flying head is that the above-mentioned contact pressure is changed in the pseudo contact head or the contact head. It becomes a factor. When the contact pressure changes in these heads, the frictional force changes, which adversely affects seek control and track following control.
Further, if the contact pressure changes in a direction in which the contact pressure increases, the surface of the medium may be damaged, dust may be generated, or the electromagnetic transducer may be damaged. On the other hand, if the above-described driving voltage control method is applied to a quasi-contact type or contact type head, the fluctuation of the contact pressure can be suppressed, so that the reliability can be improved.

It should be noted that such a positioning mechanism capable of suppressing the displacement in the floating direction can be applied to, for example, a thin fine movement mechanism portion having an assembly structure described in Japanese Patent Application Laid-Open No. 6-259905. And it is possible to suppress unintended displacement in the flying direction due to an assembly error.

The case where the present invention is applied to a magnetic head has been described above. However, the present invention is also applicable to a recording / reproducing head used in a recording / reproducing apparatus for an optical recording medium such as an optical disk. A similar effect is realized. A recording / reproducing head (optical head) for an optical recording medium to which the present invention can be applied has a slider similar to the above-described magnetic head, and an optical module is incorporated in the slider, or the slider itself is constituted by the optical module. It is. The optical module has at least a lens, and further incorporates a lens actuator, a magnetic field generating coil, and the like as necessary. As such an optical head, specifically, for example, a flying head (described in the above-mentioned US Pat. No. 5,497,359) used for near-field recording is mentioned, but in addition to this, The present invention can also be applied to an optical head in which a slider slides on the surface of a recording medium, that is, a pseudo contact type or contact type optical head. The operation and effect of the optical head can be easily understood by replacing the electromagnetic transducer with an optical module in the above description.

In this specification, a recording / reproducing head is a concept including a recording / reproducing head, a recording-only head, and a reproducing-only head, and a recording / reproducing device is also a recording / reproducing device, a recording-only device, and a reproducing-only device. The concept includes The recording medium is not limited to a recordable medium, and includes a read-only medium such as a read-only optical disk.

Hereinafter, embodiments of the present invention will be described with reference to the drawings by taking a magnetic head as an example, but as described above, the present invention can also be applied to an optical head.

FIG. 1 is a perspective view for explaining the basic configuration and operation of the magnetic head of the present invention. The magnetic head shown in FIG.
A slider 2 having an electromagnetic transducer 1 and a suspension 3 supporting the slider 2;
An actuator 4 is provided between the actuator 3 and the suspension 3. The actuator 4 has a structure in which a displacement generating section, a fixed section, and a movable section are integrally formed. The displacement generating section is provided with at least one piezoelectric / electrostrictive material layer having an electrode layer on both sides, and is configured to generate expansion and contraction by applying a voltage to the electrode layer. The piezoelectric / electrostrictive material layer is made of a piezoelectric / electrostrictive material that expands and contracts by an inverse piezoelectric effect or an electrostrictive effect. One end of the displacement generating unit is connected to the slider 2 via the fixed unit, and the other end of the displacement generating unit is connected to the suspension 3 via the movable unit. The electromagnetic transducer 1 is configured to be displaced linearly or arcuately so as to intersect the recording track of the disk medium 6.

FIG. 2 shows an exploded perspective view of a configuration example of the magnetic head of the present invention. The actuator shown in FIG.
44 are further provided, and two bar-shaped beam portions for connecting them are provided in parallel, and the two beam portions are each provided with an electrode layer.
45 is provided to constitute the displacement generating section 41. The fixed portion 43 has a frame shape, and the displacement generating portion 41 and the movable portion
The structure surrounds 44. The movable part 44 is the slider 2
The fixing portion 43 is connected to the suspension 3 by bonding or the like.

The entire actuator shown in FIG.
By forming two holes in a plate of piezoelectric / electrostrictive material provided with 45, a displacement generating part 41, a fixed part 43 and a movable part are formed.
44 is formed. This structure is the same in the actuators shown in FIGS.

In addition, in the figure, in order to clearly show the displacement generating unit 41, the electrode layer 45 is illustrated as being present on the surface of the displacement generating unit, but usually, the electrode layer is not exposed on the actuator surface, and will be described later. As a result, a structure is provided in which a piezoelectric / electrostrictive material layer as a cover portion is present on the surface of each electrode layer. The same applies to the following illustrated examples.

When the piezoelectric / electrostrictive material layer sandwiched between the pair of electrode layers 45 in the displacement generating section 41 is made of a so-called piezoelectric material such as PZT, the piezoelectric / electrostrictive material layer usually has an improved displacement performance. Polarization processing is performed. The polarization direction by this polarization processing is the thickness direction of the plate-like body. When the direction of the electric field when a voltage is applied to the electrode layer matches the direction of the polarization, the piezoelectric / electrostrictive material layer between the two electrodes extends in the thickness direction (piezoelectric longitudinal effect), and in the in-plane direction, Shrink (piezoelectric lateral effect). On the other hand, when the direction of the electric field is opposite to the direction of the polarization, the piezoelectric / electrostrictive material layer contracts in its thickness direction (piezoelectric longitudinal effect) and elongates in its in-plane direction (piezoelectric transverse effect). In the illustrated example, the movable section 44 is displaced in an arc shape in the direction of the arrow in the drawing by utilizing the piezoelectric lateral effect, that is, expansion and contraction in the direction connecting the fixed section 43 and the movable section 44. Then, the slider 2 is swung by this displacement, and the electromagnetic transducer 1 is displaced in an arc shape so as to intersect the recording track.

In the configuration shown in the figure, when a voltage that causes contraction is alternately applied to one of the displacement generating units and the other, the ratio of the length of one of the displacement generating units to the length of the other of the displacement generating units is reduced. As a result, the two displacement generating portions bend in the same direction in the plane of the plate-shaped body, that is, in the plane of the actuator. Due to this bending, the movable portion is
44 swings in the direction of the arrow in the figure with the position where no voltage is applied as the center. This swing is a displacement in which the movable portion 44 draws an arc-shaped trajectory in a direction substantially perpendicular to the direction of expansion and contraction of the displacement generating portion 41. At the center of the arc-shaped trajectory, both beam portions are connected to the fixed portion 43. It is near the center of two places. Since the swing direction of the movable portion 44 exists in the plane of the actuator, the electromagnetic transducer 1 also swings along an arc-shaped locus. At this time, since the direction of the voltage is the same as that of the polarization, there is no fear of the polarization decay, which is preferable. Even if the voltage applied alternately to the two displacement generating portions causes the displacement generating portions to extend, similar swinging occurs.

Further, in this configuration, voltages that cause displacements opposite to each other may be simultaneously applied to both displacement generating units. That is, an alternating voltage may be simultaneously applied to one displacement generating unit and the other displacement generating unit such that when one expands, the other contracts, and when one contracts, the other expands. At this time, the swing of the movable portion 44 is centered on the position where no voltage is applied. In this case, when the driving voltage is the same, the amplitude of the swing is about 2 in the above case where the voltage is applied alternately.
Double. However, in this case, the displacement generating portion is extended on one side of the swing, and the driving voltage at this time is opposite to the direction of the polarization. Therefore, when the applied voltage is high or when the voltage is continuously applied, the polarization of the piezoelectric / electrostrictive material may be attenuated. Therefore, by applying a constant DC bias voltage in the same direction as the polarization and superimposing the alternating voltage on the bias voltage as the drive voltage, the direction of the drive voltage may be opposite to the direction of the polarization. Not to be. In this case, the swing is centered on the position when only the bias voltage is applied.

As a modification of the configuration shown in FIG. 2, a configuration in which a displacement generating section is provided only in one of the beam sections may be adopted. in this case,
Similar to the configuration of FIG. 2, a configuration may be adopted in which not only contraction but also extension of the displacement generating portion is performed to increase the displacement amount, or polarization may be prevented from being attenuated by applying a bias voltage.

In the actuator shown in FIG. 3, a frame-shaped solid portion 43 and a movable portion 44 are connected by two rod-shaped beams, and each beam is provided with a pair of electrode layers 45 to form a displacement generating portion 41. In this respect, the configuration is the same as that of FIG. 2, and the polarization of the piezoelectric / electrostrictive material is also the same as that of FIG. However, in this configuration, a hinge portion 421 is provided. The hinge part 421 is
This is a region of the beam between the displacement generator 41 and the movable unit 44. The hinge portion 421 has a width with respect to the thickness,
The rigidity in the in-plane direction of the actuator is lower than that of the displacement generating section 41.

In this configuration, when a voltage is applied such that one of the displacement generating portions and the other displacement generating portion cause a displacement opposite to each other, the hinge portion 421 has a relatively low rigidity. Therefore, since the rigidity of the displacement generating portions is relatively high, the bending is small. As a result, the movable portion 44 makes a rotational displacement around the center of the two connecting portions with the two beam portions,
The electromagnetic conversion element 1 draws an arc-shaped trajectory.

In this configuration, as the rigidity of the hinge portion relative to the displacement generating portion 41 is relatively low, the deflection of the displacement generating portion 41 decreases,
As a result, the movable portion 44 per unit contraction amount of the displacement generation portion 41
Increases the rotation angle.

Also in this configuration, similarly to the configuration in FIG. 2, a voltage that causes contraction or extension may be alternately applied to one displacement generation unit and the other displacement generation unit. In addition, an electrode layer may be provided only on one of the beam portions. In this case, the center of rotation of the movable portion 43 is near the hinge portion of the beam portion on which the electrode layer is not provided.

Each of the actuators shown in FIGS. 4 and 5 has a frame-shaped fixing portion 43 constituting an outer frame of the actuator, a movable portion 44 surrounded by the fixing portion 43, and an L-shaped beam portion connecting these. . There are two beams in FIG. 4 and four beams in FIG. The external shape of these actuators is
It is rotationally symmetric about an axis of symmetry (the Z axis in the figure) that is perpendicular to the plane and passes through the center of the movable part 44.

In these configurations, when a voltage is applied such that both the displacement generating sections contract or expand simultaneously, the movable section 44
Makes a rotational movement about the axis of symmetry, and the electromagnetic transducer 1 draws an arc-shaped trajectory. In these configurations, since the slider is rotationally driven, the reversal due to the driving is small, and the vibration characteristics of the magnetic head are not adversely affected. Further, since the slider can be driven to rotate in the configuration shown in FIG. 3, the same effect can be achieved. Here, to rotate the slider means to rotate the slider about an axis passing through the slider.

In these configurations, the displacement generating section of the beam section
The region between the movable portion 44 and the movable portion 44 is shaped like a hinge portion 421 in FIG. 3 so that the rigidity in the in-plane direction of the actuator is lower than that of the displacement generating portion 41, thereby acting as a hinge portion. You may give it.

In these configurations, since the beam portion is formed parallel to the longitudinal direction of the slit-shaped hole portion between the fixed portion 43 and the movable portion 44, that is, the beam portion is formed so as to traverse the slit-shaped hole portion, the displacement generating portion The length of 41 can be increased, and as a result, the rotation angle of the movable section 44 can be increased. However, if necessary, a configuration may be adopted in which a beam is provided so as to cross the slit-shaped hole.

In order to cause the movable portion to perform the rotary motion, the number of the beam portions need not be two or four, but may be three or five or more. Also, the shape of the outer periphery and the inner periphery of the frame-shaped fixed portion and the movable portion is not limited to a square shape, but may be, for example, another polygonal shape or a circular shape.

In FIG. 5, there are two pairs of beam parts symmetrical with respect to the axis of symmetry, but it is also possible to provide an electrode layer in only one of these pairs. In this case, the other set of beams serves as a support or hinge.

4, an electrode layer may be provided only on one of the beams. Further, an electrode layer may be provided only on one of the beam portions, and the other beam portion may be provided so as to cross the slit-shaped hole portion to serve as a hinge portion. However, in these configurations, the central axis of the rotational movement is deviated from the center of the movable part.

FIG. 6 shows an example of the configuration of an actuator in which the movable portion is linearly or rotationally displaced relative to the fixed portion in the plane of the plate-like pair as the displacement generating portion bends as the displacement generating portion expands and contracts.

The actuator 4 shown in the figure has a frame-shaped fixed part 43, and inside the fixed part 43, two pairs of displacement generating parts each composed of a movable part 44 and two parallel displacement generating parts parallel to each other. That is, it has a first pair (displacement generators 411a and 411b) and a second pair (displacement generators 412a and 412b). In each pair, the directions of expansion and contraction are parallel to each other.

In the plane of the actuator, an axis passing through the movable portion 44 and perpendicular to the direction of expansion and contraction of the displacement generating portion is defined as an X axis. The first pair and the second pair are arranged mirror-symmetrically with respect to the X axis.

Each displacement generating part is provided with a fixed connecting part 431, 4 provided on the fixed part 43.
Connected to 32. These fixed connecting portions are formed by providing slit-shaped holes in a part of the frame-shaped fixing portion 43, and are regions having a small width and a low rigidity in an in-plane direction. The reason why the displacement generating section is connected to the fixed connecting section having low rigidity is that the expansion and contraction of the displacement generating section are not hindered. The means for lowering the rigidity of the fixed connecting portion is not particularly limited, and in addition to the structure shown in the drawing, for example, a portion of the fixed portion 43 is made thinner, such as the fixed connecting portions 431 to 434 in FIG. It is good also as a structure which does. Since the fixed connection portion needs to be deformed when the actuator is driven, the fixed connection portion does not adhere when the fixed portion of the actuator is bonded to the suspension. This is the same for the actuator of FIG. 10 described later.

FIG. 7A and FIG. 7B are exaggerated plan views showing the deformation of each part when the actuator is driven. The operation of this actuator will be described with reference to these drawings.

When driving the actuator, the displacement generating units 411a, which are present on one side (hereinafter, left side in the figure) of each pair,
When the displacement generating portions 411b and 412b existing on the other side (hereinafter, the right side in the figure) of each pair are expanded while the 412a is contracted, as shown in FIG. 7A, the expansion and contraction of each displacement generating portion is not hindered. As described above, the fixed connecting portions 431 and 432 bend, and as a result, all the displacement generating portions bend so as to be convex to the right, so that the movable portion is linearly displaced to the right.

Also, when the first pair of left-side displacement generators 411a and the second pair of right-side displacement generators 412b are contracted and the other displacement generators 411b and 412a are extended, as shown in FIG. 7B, Fixed connecting parts 431, 4 so as not to hinder the expansion and contraction of each displacement generating part
As a result, the first pair bends so as to be convex to the right and the second pair bends so as to be convex to the left.
Will be rotated clockwise in the figure around the Z axis perpendicular to the plane of the actuator.

As described above, in the configuration shown in FIG. 6, if the positional relationship between the contracting displacement generating section and the extending displacement generating section is mirror-symmetric with respect to the X axis, the movable section is linearly displaced. On the other hand, if this positional relationship is rotationally symmetric with respect to the Z axis, the movable part is rotationally displaced.

In the above-described linear displacement or rotational displacement, if the contracting displacement generating section and the extending displacement generating section are exchanged, the bending direction of the displacement generating section is reversed, and the movable section 44 is linearly displaced to the left in the drawing, It will be rotationally displaced in the counterclockwise direction.

In the illustrated example, the expansion and contraction directions of each pair are parallel to each other. However, the expansion and contraction directions of each pair need not be parallel, and the two displacement generating units forming each pair need not be parallel. The direction of expansion and contraction of each displacement generating portion need not be parallel to the target displacement direction (X-axis direction in the figure). That is,
The first pair and the second pair only need to be arranged to face each other with the X axis interposed therebetween, and there is no particular limitation on the angle between the two pairs and the angle between the two displacement generating parts of each pair. For example, in order to improve rigidity, both pairs or both pairs of displacement generating portions may not be parallel.

In the configuration shown in FIG. 6, similarly to the configuration shown in FIG. 2, one of the displacement generating portions of each pair may be a beam portion that does not expand and contract. Even in that case, linear displacement and rotational displacement of the movable part are possible.

The operation principle of the actuator shown in FIG. 6 is the same as that of the actuator shown in FIG. 2 in using the bending of the displacement generating section. However, in the configuration shown in FIG. 6, since the movable portion is supported from two opposing directions (vertical direction in the figure), the rigidity in the in-plane direction and the direction perpendicular to the plane (flying direction) is increased. Therefore, when external force due to contact with the disk medium or acceleration due to impact on the device is applied to the slider,
The blur in the in-plane direction and the direction perpendicular thereto is reduced.

FIG. 8 shows an example of the configuration of an actuator in which the displacement generating section flexes and the movable section linearly displaces with respect to the fixed section in the plane of the plate-like body as the displacement generating section expands and contracts.

The actuator 4 shown in the figure has a fixed part 43 of a frame body, inside the fixed part 43, a movable part 44 and four pairs of displacement generating parts each composed of two parallel displacement generating parts,
That is, a first pair (displacement generating units 411a and 411b), a second pair (displacement generating units 412a and 412b), and a third pair (displacement generating unit 413).
a, 413b) and a fourth pair (displacement generators 414a, 414b). In each pair, the directions of expansion and contraction are parallel to each other. However,
In the configuration shown in FIG. 8, similarly to the configuration shown in FIG. 6, the expansion and contraction directions of each pair do not need to be parallel, and the two displacement generating portions forming each pair do not need to be parallel. ,
The direction of expansion and contraction of each displacement generating section need not be parallel to the target displacement direction (X-axis direction in the figure).

In the plane of the actuator shown in FIG.
, The axis perpendicular to the direction of expansion and contraction of the displacement generating section is defined as the X axis. On one side of the X axis (hereinafter, upper side in the figure), the first
A second pair of pairs exists with a gap therebetween and the movable part 44 therebetween,
On the other side of the X-axis (hereinafter, the lower side in the figure), a third pair and a fourth pair exist with a gap therebetween with the movable portion 44 interposed therebetween.

The fixed part 43 is a fixed connecting part for connecting the displacement generating part.
431 and 432, which extend along the X-axis toward the movable portion 44 and sandwich the movable portion 44 with a gap. movable part
44 is a movable connecting portion 441, 44 for connecting the displacement generating portion.
2, 443, 444, and the movable connecting parts 441, 442
The movable connecting portions 443 and 444 extend from one end of the
Extends from the other end of the movable portion 44 in parallel with the X axis. The first pair has one end connected to the fixed connection portion 431 and the other end connected to the movable connection portion 441, the second pair has one end connected to the fixed connection portion 432 and the other end connected to the possible connection portion 442, and the third pair has One end is fixed connection part 431
The other end is connected to the movable connecting portion 443, and the fourth pair is connected at one end to the fixed connecting portion 432 and at the other end to the movable connecting portion 444.

When driving the actuator, the displacement generating units 411a, which are present on one side (hereinafter, left side in the figure) of each pair,
412a, 413a, and 414a are contracted, and the displacement generating section 411 existing on the other side (hereinafter, right side in the figure) in each pair.
When b, 412b, 413b, and 414b are extended, each displacement generating section bends to the left, and the movable section 44 is displaced linearly to the left. On the other hand, if the contracting displacement generating section and the extending displacement generating section are exchanged, the direction in which the displacement generating section bends is reversed, and the movable section 44
Will be displaced linearly to the right.

In the configuration shown in FIG. 8, similarly to the configuration shown in FIG. 2, one displacement generating portion of each pair may be a beam portion that does not expand and contract. Even in that case, linear displacement of the movable part is possible.

It is preferable that the movable connecting portions 441, 442, 443, and 444 have low rigidity in the in-plane direction as illustrated.
This is because the expansion and contraction of the displacement generating portion is not hindered.

The operation principle of the actuator shown in FIG. 8 is the same as that of the actuator shown in FIG. 6 in that the deflection of the displacement generating section is used. However, since the number of logarithms of the displacement generating section is larger than that of the configuration shown in FIG. It is more preferable because the driving force increases.

FIG. 9 shows an example of the configuration of an actuator in which the displacement generator flexes as the displacement generator expands and contracts, and the movable part rotates and displaces in the plane of the plate-like body with respect to the fixed part.

The actuator 4 shown in the figure has a frame fixed portion 43, and inside the fixed portion 43, a movable portion 44 and two pairs of displacement generating portions each composed of two parallel displacement generating portions. That is, it has a first pair (displacement generators 411a and 411b) and a second pair (displacement generators 412a and 412b). In each pair, the directions of expansion and contraction are parallel to each other.

A straight line perpendicular to the plane of the actuator and passing through the movable portion 44 is defined as a Z line. The first pair and the second pair sandwich the movable portion 44 with an air gap therebetween, and the connecting portion between each pair and the movable portion is located symmetrically with respect to the Z axis, and the connection between each pair and the fixed portion is provided. The part is Z
It is located symmetrically with respect to the axis.

In this configuration, similarly to the configuration shown in FIG. 6, the expansion and contraction directions of each pair need not be parallel, and the two displacement generating portions forming each pair need not be parallel. , The connecting portion between each pair and the movable portion faces each other across the Z axis,
In addition, it is only necessary that the connecting portion between each pair and the fixing portion faces each other with the Z axis interposed therebetween.

The movable section 44 is a movable connecting section for connecting the displacement generating section.
441 and 442, which are opposed to each other across the Z axis. The movable connecting part 441 and the movable connecting part 442 extend at one end and the other end of the movable part 44, respectively, so as to be orthogonal to the direction of expansion and contraction of the displacement generating part. The first pair has one end connected to the fixed portion 43 and the other end connected to the movable connection portion 441, and the second pair has one end connected to the fixed portion 43 and the other end connected to the movable connection portion 442.

When the actuators are driven, the pair of displacement generators 411a and 412b that are relatively far from the Z axis are contracted and the pair of displacement generators 411b and 412b that are relatively closer to the Z axis are extended. The movable portion 44 is rotationally displaced in the clockwise direction in the figure around the Z axis since the movable portion 44 is bent in a direction away from the movable member 44. When the contracting displacement generating section and the extending displacement generating section are exchanged, the direction in which the displacement generating section bends is reversed, and the movable section 44 is rotationally displaced counterclockwise in the drawing.

In the configuration illustrated in FIG. 9, similarly to the configuration illustrated in FIG. 2, one displacement generating unit of each pair may be a beam that does not expand and contract. Even in that case, rotational displacement of the movable part is possible.

The movable connecting portions 441 and 442 have low rigidity in the in-plane direction for the same reason as the movable connecting portion shown in FIG.

The actuator shown in FIG. 9 has the same operating principle as the actuator shown in FIG. 2 in that the deflection of the displacement generating portion is used. However, in the configuration shown in FIG. 9, the movable portion is supported from two opposing directions. Since the number of displacement generating parts is large, the rigidity is further increased.

FIG. 10 shows an example of the configuration of an actuator in which the displacement generating section bends and the movable section rotates and displaces relative to the fixed section in the plane of the plate-like body as the displacement generating section expands and contracts.

The actuator 4 shown in the figure has a frame-shaped fixed portion 43, and inside the fixed portion 43, a movable portion 44 and four pairs of displacement generating portions each composed of two parallel displacement generating portions. That is, a third pair (displacement generating unit) of the first pair (displacement generating units 411a and 411b) and the second pair (displacement generating units 412a and 412b).
413a, 413b) and a fourth pair (displacement generators 414a, 414b). Each pair extends radially from the movable portion 44 at an interval of 90 ° so that the first pair and the third pair and the second pair and the fourth pair face each other. , 43
2, 433 and 434 are connected respectively.

An axis perpendicular to the plane of the actuator and penetrating the movable portion 44 is defined as a Z axis. When driving this actuator, Z
Displacement generating parts 411a, 412a, 413a, 414a existing on one side of each pair as viewed from the axis (left side in the figure as viewed from the Z axis) are contracted, and the other side of each pair as viewed from the Z axis (from the Z axis). (Right side in the drawing) displacement generating parts 411b, 412b, 413b, 41
When 4b is extended, each displacement generating portion bends to the one side as viewed from the Z axis, and the movable portion 44 is rotationally displaced clockwise in the figure. On the other hand, if the contracting displacement generating part and the extending displacement generating part are exchanged, the direction in which the displacement generating part bends is reversed,
The movable portion 44 is rotationally displaced in the counterclockwise direction in the drawing.

In the configuration shown in FIG. 10, similarly to the configuration shown in FIG. 2, one of the displacement generating portions of each pair may be a beam portion that does not expand and contract. Even in that case, rotational displacement of the movable part is possible.

The fixed connecting portions 431, 432, 433, and 434 need to bend so as not to hinder the expansion and contraction of each displacement generating portion, similarly to the fixed connecting portions 431 and 432 shown in FIG. And the rigidity in the in-plane direction is low. In addition,
The structure of the fixed connecting portion is not limited to the one shown in the figure, and may be, for example, as shown in FIG.
It may be formed by providing a slit-shaped hole in a frame-shaped fixing portion like the fixing connecting portion shown in FIG.

The operation principle of the actuator shown in FIG. 10 is the same as that of the actuator shown in FIG. That is, the positional relationship between the contracting displacement generating section and the extending displacement generating section is rotationally symmetric about the Z axis, and the movable section is rotationally displaced. However, the configuration shown in FIG. 10 supports the movable part from four directions.
Since the number of displacement generating parts is large, the rigidity is further increased and the driving force is also increased, which is more preferable.

The actuator shown in each of the drawings has a structure in which the fixed portion extends in the plane of the actuator so as to surround the displacement generating portion and the movable portion. By forming the fixing portion in a frame shape, handling of the actuator is facilitated. For example, when the actuator is gripped by tweezers or the like, the frame-shaped portion of the fixed portion can be gripped, so that the displacement generating portion can be prevented from being damaged. Further, by providing the frame-shaped portion, damage to the actuator due to dropping or the like can be reduced. Also, since the bonding area when fixing the actuator to the substrate is increased, the bonding strength is increased and the bonding / attachment work is facilitated. Further, since the fixing portion is connected to the suspension in the form of a thin plate, an effect of increasing the rigidity of the connecting portion is also realized.

The fixing portion in each of the above-described configurations is a frame-like body that completely surrounds the displacement generating portion and the movable portion. However, as long as the fixing portion can be displaced without the frame shape, the fixing portion does not need to have the frame shape. Good. For example, a notch may be provided in a part of the fixing part as needed, and a frame-like part may not be provided in the fixing part as in the configuration of FIG. 11 described later.

Each of the actuators shown in FIGS. 2, 3, 4, 5, 6, 8, 9, and 10 has at least two holes in a plate made of a piezoelectric / electrostrictive material. Thereby, the fixed portion 43, the movable portion 44, and at least two beam portions connecting these are integrally formed, and at least one beam portion is formed.
An electrode layer is provided on at least a part of one of the beam portions so as to expand and contract in a direction connecting the fixed portion 43 and the movable portion 44 to constitute a displacement generating portion. Then, with the expansion and contraction of the displacement generating portion, the displacement generating portion is bent and the movable portion is displaced in an arcuate, rotational, or linear manner in the plane of the plate-like body with respect to the fixed portion.

Configuration in which Actuator is Arranged on Side Surface of Slider The actuator shown in FIG. 11 has two rod-shaped displacement generating portions 41 connecting the fixed portion 43 and the movable portion 44, and the side surface of the movable portion 44 and the slider 2 The side is bonded. This actuator has the same configuration as the actuator shown in FIG. 2 except that the fixing portion 43 is not formed in a frame shape.

The configuration shown in FIG. 12 uses an actuator in which a movable portion 44 is provided at the end of two rod-shaped displacement generating portions 41 extending from the fixed portion 43, and each of the sliders 2 is sandwiched between the two displacement generating portions. The movable portion 44 is connected to each of a pair of opposing side surfaces of the slider 2. This configuration is shown in FIG.
As in the above configuration, the bending displacement of the displacement generating portion is used, and the displacement of the electromagnetic displacement element 1 is an arc-shaped displacement.

In the configuration where the actuator is arranged on the side of the slider,
By using an actuator that is thinner than the slider as in the illustrated example, the thickness of the magnetic head does not increase, and there is no fear that the actuator contacts the disk medium.

Even if the actuator has the same thickness as or thicker than the slider, if the actuator is arranged on the side surface of the slider, for example, as shown in FIG. 13, the slider 2 and the actuator 4 overlap in the thickness direction. An increase in the thickness of the magnetic head can be suppressed by the dimension A.

The actuators shown in FIGS. 11 and 12 also have a fixed portion 43, a movable portion 44, and a beam portion having a displacement generating portion 41 by providing holes and cutouts in a plate made of a piezoelectric / electrostrictive material. Are integrally formed.

FIG. 14 shows a configuration in which the actuator is arranged in a space formed by a step provided on the slider. In FIG. 14, a step is formed on the back surface of the rectangular parallelepiped slider 2 by cutting or the like so as to leave a portion where the electromagnetic transducer 1 is formed.
The actuator 4 is placed in the space 21 formed by the step.
Has been arranged. With this configuration, the increase in the thickness of the magnetic head due to the provision of the actuator can be suppressed.
The mass of the slider is reduced.

In FIG. 15, two steps are provided on the back surface of the slider 2 so that a groove-shaped space 21 is provided substantially at the center of the back surface of the slider 2.
Is formed, and the actuator 4 is arranged in this space. In this configuration, in addition to the effect of the configuration in FIG. 14, the slider mass balance is improved, which is more preferable for the displacement characteristics.

Although FIGS. 14 and 15 show an example in which the actuator having the configuration shown in FIG. 2 is used, it goes without saying that an actuator having another configuration may be used.

A configuration in which the slider and the actuator are arranged with the suspension interposed.When positioning is performed by swinging the magnetic head with the VCM, if the mass is unbalanced between the upper and lower surfaces of the suspension, the slider may be twisted or momentated. Is hindered from stable movement. In the magnetic head shown in FIG. 16, since the actuator is arranged on the upper surface of the suspension 3 and the slider 2 is arranged on the lower surface of the suspension 3, the imbalance is improved and the slider 2 can move stably. In this configuration, if the actuator 4 and the slider 2 have substantially the same mass, the center of gravity G of the structure including the slider 2 and the actuator 4 comes near the extension of the surface of the suspension 3 as shown in FIG. Therefore, the imbalance is substantially eliminated. This configuration can be applied to an actuator other than the illustrated example.

In the illustrated example, in order to provide a gap for disposing the suspension 3 between the slider 2 and the actuator 4, a projecting connecting portion 2 a is integrally formed on the back surface of the slider 2, and this connecting portion 2 a is connected to the actuator 2. 4. Generally, such protrusions are provided,
As shown in FIG. 14, it is preferable that a notch is provided on the back surface of the slider 2 so that the slider and the connecting portion are integrally formed. However, a configuration may be used in which the slider and the actuator are connected by using an independent connecting member having the same shape as the connecting portion 2a. Further, the connecting member as shown may be formed integrally with the actuator. Further, as shown in FIG. 21 described later, a configuration may be employed in which a part of the suspension is used as a connecting member.

A structure in which an actuator is connected to the gimbal portion of the suspension Usually, a gimbal mechanism such as a flexure is provided near the tip of the suspension so that the slider can follow the fluctuation of the disk medium surface. FIG. 1 is a diagram illustrating a configuration example when the present invention is applied to a magnetic head having a gimbal mechanism.
18A, FIG. 19A, FIG. 20A, and FIG.

The configuration shown in FIG. 18A as a plan view and FIG. 18B as a side view is an example in which a conventional suspension 3 having a gimbal portion by connecting a flexure 31 is used. Also, FIG. 19A is a plan view,
FIG.19B is a side view, and FIG.20A is a plan view.
The configuration shown in the side view at 20B is an example in which the suspension 3 is provided with a punched groove by etching or the like to form the gimbal portion 32. In any case, the actuator 4 is connected to the gimbal portion of the suspension 3 so as not to hinder the gimbal function. With such a configuration,
The gimbal portion absorbs torsion, stress, and the like caused by following the disk medium surface, so that unnecessary external force is not applied to the actuator, and displacement performance and reliability are not impaired. In the illustrated gimbal portion, the configuration shown in FIG. 19A and the configuration shown in FIG. 20A are preferable, and the configuration shown in FIG. 20A is more preferable because the rigidity of the slider 2 in the displacement / drive direction is high. When using the suspension having the gimbal portion shown in each of FIGS. 19A and 20A, it is possible to adopt a configuration in which the slider and the actuator are arranged with the suspension interposed therebetween.

The configuration shown in FIG.
This is an example in which the slider 2 and the actuator 4 are arranged with the. The gimbal portion 32 is formed by providing a punched groove in the suspension 3. The gimbal portion 32 has a T-shaped connecting portion formed by providing a punched groove. The connecting portion is composed of a supporting portion 32a corresponding to a vertical T-bar and continuous with the gimbal portion 32, and a connecting portion 32b corresponding to a horizontal T-bar. Connection part 32b
The movable part 44 of the actuator 4 is adhered to the surface side,
The slider 2 is bonded to the back side. The support portion 32a has a low rigidity so as not to hinder the displacement of the movable portion 44. The connecting portion 32b in this configuration can be regarded as a rigid body when it is bonded to the movable portion 44 and the slider 2, so that the effect of the present invention is not impaired.

It is not necessary to connect the connecting part 32b to the gimbal part 32 by the support part 32a. That is, like the connecting portion 2a shown in FIG.
A configuration in which only 32b is provided may be adopted.

In the present invention, wiring to the actuator and / or the electromagnetic transducer is preferably performed by providing a conductor pattern on the suspension. FIG. 21 shows a case where four wiring patterns 33 connected to the electromagnetic transducer 1 are formed on the lower surface of the suspension.

Configuration for Amplifying Displacement Amount of displacement generated by the inverse piezoelectric effect or the electrostriction effect (the amount of contraction of the displacement generating portion) is extremely small. However, in the present invention, when the movable portion is displaced by using the deflection of the displacement generating portion, the displacement of the connecting portion between the slider and the actuator (the movable portion of the actuator) is made larger than the amount of expansion and contraction of the displacement generating portion. It is possible. That is, it is possible to provide the actuator itself with a displacement enlarging function. Further, in the present invention, when the movable portion is displaced in an arc or in a rotational manner, the displacement of the electromagnetic transducer is mechanically enlarged by appropriately setting a positional relationship between the movable portion and the electromagnetic transducer. be able to. By enlarging the displacement by these, in the present invention, the displacement amount of the electromagnetic transducer can be made practical.

As an example in which the actuator itself has the displacement enlarging function, for example, FIGS. 2, 4, 5, 6, 8, 9, and FIG.
1, and the configuration shown in FIG.

The actuator 4 shown in FIG. 22A is an example of a configuration in which the actuator itself has a displacement enlarging function. FIG. 22A is a plan view, and a side view thereof is shown in FIG. 22B. The actuator 4 in the figure is similar to the actuator in FIG.
The movable portion 44 is displaced in an arc shape by bending of the beam portion.
In this actuator 4, assuming that only one of the displacement generating portions 41 contracts and the contraction amount is A, the displacement amount B of the movable portion 44 which is a connecting portion with the slider can be made larger than the contraction amount A. Note that the displacement amount of the movable part 44 and the displacement amount of the electromagnetic transducer 1 are substantially the same. For example, the displacement generating part is 1 mm in length, 0.1 mm in width, and 0.2 mm in thickness, the width of the slit-shaped hole between the two displacement generating parts is 0.1 mm, and the shrinkage amount of the displacement generating part is about 0.2 μm. , The displacement of the movable part (the displacement in the direction perpendicular to the length direction of the displacement generating part) is approximately
Since it is 0.5 μm, the displacement magnification is about 2.5 times. The arrows in the figure indicate the contraction direction of the displacement generating unit 41 and the displacement direction of the movable unit 44.

In addition, for example, in a configuration in which the movable portion is rotationally displaced as shown in FIG. 4, the displacement amount of the movable portion is larger than the expansion / contraction amount of the displacement generating portion. Is larger than the amount of expansion and contraction of the displacement generating portion.

FIGS. 2, 3, 4, 5, and 5 are examples of an example in which the movable portion undergoes an arc-shaped displacement or a rotational displacement, and the displacement amount can be mechanically enlarged, or the displacement amount is mechanically enlarged. 6 (in the case of rotational displacement), configurations shown in FIGS. 9, 10, 11, 12 and the like. When the movable portion is displaced in an arc or rotated, the electromagnetic transducer is displaced in an arc concentrically with the displacement of the movable portion. If the slider and the movable part are connected so that the radius of rotation of the arc-shaped displacement of the electromagnetic transducer is larger than the radius of rotation of the arc-shaped displacement or the rotational displacement of the movable part, the amount of displacement is smaller than the displacement of the connecting part between the slider and the movable part. The displacement of the electromagnetic transducer can be increased. FIG. 23A is a plan view of a configuration in which the connecting portion between the movable portion 44 and the slider 2 is located farther from the electromagnetic transducer 1 than the connecting portion in FIG. 22A, and a side view thereof is shown in FIG. 23B. . As shown in the figure, by making the distance of the electromagnetic transducer 1 from the center of the arc-shaped displacement larger than that of the movable part 44, the displacement C of the electromagnetic transducer 1 is made larger than the displacement B of the movable part 44. it can. Assuming that the dimensions of the actuator are the same as those in the description of FIG. 22A, for example, by displacing the position of the connecting portion between the movable portion 44 and the slider 2 by 0.5 mm from the electromagnetic transducer 1, the displacement amount C becomes approximately the displacement amount B. 1.5 times.

Details of Actuator The actuator shown in FIG. 24 has two holes in a frame-shaped fixing portion 43 of the actuator having the same configuration as that of FIG.
The flexible filler 46 is filled so as not to protrude from the plane of the actuator.

By filling the hole with the flexible filler as in the illustrated example, a vibration damping effect is obtained, and the influence of resonance and harmful vibration from the outside is suppressed. Moreover, since the flexible filler bridges each part of the actuator, the mechanical strength and impact resistance of the actuator are improved.

FIG. 24 shows a configuration in which the electrode layer exists inside the displacement generating section 41. In this configuration, the end surfaces of the electrode layer are exposed on both side surfaces of the displacement generating section 41, but the flexible filler covers the both side surfaces, so that corrosion of the electrode layer can be suppressed. It is preferred that the flexible filler has a specific electrolytic corrosion property.

The flexible filler may be filled in only one of the holes of the actuator.

In this configuration, since the hole is filled with the flexible filler so as not to protrude from the plane of the actuator, the filling amount can be kept constant, and variation in performance due to variation in the filling amount can be suppressed. Also, there is no increase in the thickness of the actuator due to filling.

The type, the hardness and the filling amount of the flexible filler used in this configuration are not particularly limited, so that the influence on the displacement of the movable part is small, and the vibration damping property, the improvement in strength, and the improvement in impact resistance can be realized. It may be appropriately selected, but preferably, a non-electrolytic resin having flexibility, for example, a silicone resin or a urethane resin is used as the flexible filler.

When the flexible filler is not provided, or when the electrode layer is exposed on the side of each part not covered with the flexible filler, a coating layer is provided on the side of each part to prevent corrosion of the electrode layer. Is also good.

In an actuator utilizing in-plane bending as shown in FIG. 2 and the like, it is preferable that the width of the beam portion in a cross section perpendicular to the direction connecting the fixed portion and the movable portion is smaller than its thickness. Thereby, the rigidity of the beam portion in the in-plane direction of the actuator becomes smaller than the rigidity in the thickness direction. For this reason, the bending of the beam portion caused by the expansion and contraction of the displacement generating portion 41 is concentrated in the in-plane direction of the actuator, and the occurrence of unnecessary displacement such as tilt can be suppressed. The ratio of the width to the thickness of the beam is not particularly limited, but is preferably about 1/2 to 1/5.

The above effects are realized by applying a configuration in which the width is smaller than the thickness to at least one beam portion. However, a higher effect can be obtained by applying this configuration to all the beam portions. In addition, it is preferable to apply this configuration to all the beam portions from the viewpoint of symmetry.

In the configuration shown in FIG. 2, for example, the smaller the distance between the two beams (the distance between the center lines of the beams) connecting the movable portion 44 of the fixed portion 43, the smaller the beam per unit expansion / contraction amount of the displacement generating portion. The amount of deflection of the portion increases, and as a result, the amount of displacement of the movable portion 44 per unit of expansion / contraction increases. Further, the drive voltage required to obtain a constant displacement amount decreases as the distance between the two beams decreases. The distance between the two beams can be reduced as the width of the beams decreases. For this reason, a configuration in which the width of the beam portion is smaller than its thickness is effective in increasing the displacement amount and reducing the drive voltage.

Each of the actuators shown in FIGS. 2, 3, 6, 8, 10, 11, and 12 has an axis of symmetry (for example, FIG.
In this case, there is an X-axis that passes through the center of the slit-shaped hole between the two displacement generating portions in the longitudinal direction of the hole. For this reason,
Since the actuator can be used even if it is turned upside down, the work of attaching the actuator to the magnetic head becomes easy.

Each of the actuators shown in FIGS. 4, 5, 6, 9, and 10 has a rotationally symmetric shape about a symmetric axis (Z axis in the figure) which is perpendicular to the plane and passes through the center of the movable portion 44. (For example, two-fold rotational symmetry in FIG. 4 and four-fold rotational symmetry in FIG. 5), and the axis of symmetry coincides with the central axis of the rotational movement of the movable part 44. Therefore, when the magnetic head is mounted on the magnetic head, it is only necessary to match the center axis of the rotational motion with the predetermined rotational center position of the slider, and the mounting angle of the actuator is not limited. Becomes

Although each of the illustrated examples described above uses the expansion and contraction of the displacement generating portion due to the piezoelectric lateral effect as described above, in the present invention, the expansion and contraction in the direction coinciding with the direction of the electric field, that is, the expansion and contraction by the so-called piezoelectric longitudinal effect May be used. When the piezoelectric longitudinal effect is used, an electrode layer is provided on the displacement generating portion so as to be perpendicular to the direction connecting the fixed portion and the movable portion. However, the configuration using the piezoelectric lateral effect is preferable because it is easier to manufacture and has the advantage of increasing the mechanical strength of the actuator.

The dimensions of each part of the actuator are not particularly limited, and may be appropriately set according to the configuration of the magnetic head to be applied. However, when the actuator is considered as a plate-shaped workpiece, one side of this plate-shaped body is usually used. Is about 0.5-3.0mm, thickness is
It is about 0.1 to 0.5 mm. The length of the displacement generating part is 0.3
It is about 2.5 mm. The displacement amount is about 0.01 to 5 μm in the in-plane moving distance of the plate-like body and about 0.05 to 2 ° in the rotation angle. The driving voltage is usually about 3 to 100 V, preferably about 3 to 50 V.

In this specification, a piezoelectric / electrostrictive material means a material that expands and contracts due to an inverse piezoelectric effect or an electrostrictive effect. The piezoelectric / electrostrictive material used in the present invention may be any material as long as it can be applied to the displacement generating portion of the actuator as described above. However, because of its high rigidity, PZT [Pb (Zr, Ti )
O ₃ ], PT (PbTiO ₃ ), PLZT [(Pb, La) (Zr, Ti) O ₃ ],
Ceramic piezoelectric / electrostrictive materials such as barium titanate (BaTiO ₃ ) are preferred. When the actuator is made of a ceramic piezoelectric / electrostrictive material, it can be easily manufactured using a thick film method such as a sheet method or a printing method. Note that the actuator can also be manufactured by a thin film method. When the piezoelectric / electrostrictive material has a crystal structure, it may be a polycrystal or a single crystal.

The method for forming the electrode layer is not particularly limited, and may be appropriately selected from various methods such as firing of the conductive paste, sputtering, and vapor deposition in consideration of the method for forming the piezoelectric / electrostrictive material layer.

The actuator may have a configuration in which at least one piezoelectric / electrostrictive material layer sandwiched between electrode layers on both sides is present in the displacement generating section, and preferably, two such piezoelectric / electrostrictive material layers are provided. It is preferable to be a laminated type laminated as described above. The amount of expansion and contraction of the piezoelectric / electrostrictive material layer is proportional to the electric field strength. However, if the above-mentioned laminated type is used, the piezoelectric / electrostrictive material layer becomes thin, so that the required electric field strength can be obtained at a low voltage, and the Voltage can be reduced. If the same driving voltage is used as in the case of the single-layer structure, a larger amount of expansion and contraction can be obtained. The thickness of the piezoelectric / electrostrictive material layer is not particularly limited, and includes a driving voltage,
It may be appropriately selected according to various conditions such as the required amount of expansion and contraction, ease of production, and the like, but it is usually preferably about 5 to 50 μm. There is no particular upper limit on the number of stacked piezoelectric / electrostrictive material layers, and the upper limit may be appropriately determined so that a displacement generating portion having a desired thickness is obtained. It should be noted that, further outside of the outermost electrode layer, a piezoelectric /
An electrostrictive material layer is provided.

In the above illustrated example, the shape of the electrode layer is represented in a simplified manner in order to indicate the region of the displacement generating section.In practice, however, an internal electrode layer having a structure as shown in FIG. 25A is provided, and further,
As shown in FIG. 25B, terminal electrodes connected to these internal electrode layers are provided.

FIG. 25A shows adjacent piezoelectric / electrostrictive material layers 201 and 202 in the actuator. Internal electrode layer G ₁ on the surface of the piezoelectric-electrostrictive material layer 201, the internal electrode layers A ₁ and the internal electrode layer B ₁ is formed on the surface of the piezoelectric-electrostrictive material layer 202. The combination of the internal electrode layer G ₁ and combination and the internal electrode layer G ₁ and internal electrode layers B ₁ and internal electrode layers A ₁ is a pair of electrode layers sandwiching the piezoelectric-electrostrictive material layer, respectively. In this configuration, the internal electrode layers A ₁ and B ₁
For, by controlling the timing of each of the potential and the voltage applied to the internal electrode layer G _1, causes a displacement in the various patterns described above.

FIG. 25B is a configuration example of a terminal electrode when the internal electrode layer shown in FIG. 25A is provided. In this example, terminal electrodes G ₀ , A ₀ , and B ₀ connected to the respective end faces of the internal electrode layers G ₁ , A ₁ , and B ₁ exposed on the side surface of the fixed portion 43 are formed on the side surface of the fixed portion 43. .

The actuator may be composed of only a piezoelectric / electrostrictive material, an electrode layer, a flexible filler, and the like.
The performance and durability of the actuator can be improved by attaching an elastic plate or a vibration damping seal.

Manufacturing Method Hereinafter, as a specific example of the manufacturing method of the actuator used in the present invention, a case where a ceramic piezoelectric / electrostrictive material is used will be described.

It is preferable to use a thick film method such as a sheet method or a printing method for producing a plate-shaped body of a ceramic piezoelectric / electrostrictive material, similarly to a multilayer ceramic chip capacitor or the like. Here, an outline of the sheet method will be described. First, a paste is prepared by kneading a ceramic powder material, a binder, a solvent, and the like, and this is molded to produce a green sheet. Also, an internal electrode layer paste is prepared by kneading a conductive material, a binder, a solvent, and the like. Next, after printing the internal electrode layer paste on the green sheet so as to have a predetermined pattern as shown in FIG. 25A, for example, a predetermined number of the pastes are laminated and pressed to obtain a laminate. The laminate is fired to obtain a thin plate-like sintered body. The thin plate-shaped sintered body may be subjected to shape processing described below, but the thin plate-shaped sintered body may be cut into appropriate dimensions and then shaped.

Next, the thin plate-shaped sintered body is subjected to shape processing for providing a hole or a notch. Usually, a plurality of actuators are cut out from the thin plate-like sintered body, and this cutting is also performed at the same time as the shape processing. At the time of shape processing, first, a photoresist layer is formed on the entire surface of the thin plate-shaped sintered body. Next, after pattern exposure is performed, development is performed, and the photoresist in the region corresponding to the boundary with the adjacent actuator, the hole, and the notch is removed. Next, a region not covered with the photoresist is removed by sandblasting to cut out a plurality of actuators and obtain an actuator having a desired shape. After the shape processing, the photoresist is removed, and terminal electrodes are formed as necessary. The terminal electrode may be formed by a normal method such as baking or vapor deposition.

An ultrasonic horn may be used for the shape processing.
In ultrasonic horn processing, usually, a shape is processed by an ultrasonic horn in a state where a workpiece is immersed in an abrasive dispersion liquid.

 The shaping can be performed before firing.

In general, the displacement performance of a piezoelectric material is improved by the polarization process. Therefore, in the present invention, it is preferable to perform the polarization process as described above. Usually, the polarization treatment is performed by applying a DC voltage using the electrode layer after the actuator is formed, but may be performed at the stage of the above-described thin plate-shaped sintered body.

Usually, an adhesive is used to connect the actuator, the suspension, and the slider. The adhesive preferably has a high hardness after bonding in order to prevent displacement of the actuator due to vibration or the like of the actuator. An example of such an adhesive is an epoxy-based adhesive.

PZT (piezoelectric constant d ₃₁ = −250 × 10)
^-12 m / V) and the above-described thick film method was used to fabricate an actuator having the structure shown in FIG.

The piezoelectric / electrostrictive material layer had a thickness of 20 μm, and was a 10-layer laminate (0.2 mm in total thickness) of 8 layers sandwiched between electrode layers on both sides and one upper and lower layer serving as a cover. The displacement generator is 1 mm long,
The width was 0.1 mm and the thickness was 0.2 mm. The width of the slit-shaped hole between both the displacement generating portions was 0.1 mm, and the displacement generating portion was subjected to polarization treatment.

For this actuator, in the same direction as the polarization direction
When a voltage of 20 V is applied, the amount of contraction of the displacement generation part is about 0.2
The displacement amount of the movable portion (displacement in the direction orthogonal to the length direction of the displacement generating portion) at that time was about 0.5 μm. When the voltage was applied alternately to both displacement generating portions, the displacement of the movable portion was about ± 0.5 μm.

Drive Control Method in Magnetic Head Positioning Mechanism Next, a preferable control method for driving a magnetic head having a structure as shown in FIG. 26 will be described. The drive control method described here is preferably applied to the magnetic head of the present invention in which the entire actuator is integrally formed of a piezoelectric / electrostrictive material.
Also applicable to an actuator having a structure in which a movable portion and a displacement generating portion are assembled, and a magnetic head having an actuator manufactured in such an assembly and having a fixed portion or a movable portion made of a material other than a piezoelectric / electrostrictive material. , Is applicable.

The magnetic head shown in FIG. 26 has the same configuration as the magnetic head shown in FIG. In FIG. 26, illustration of the electrode layer of the actuator 4 is omitted.

In the configuration of FIG. 26, in order to perform the positioning correction of the electromagnetic transducer 1, a control signal for performing coarse movement in the head positioning control circuit 7 based on the track position signal reproduced from the disk medium by the electromagnetic transducer 1 and A control signal for performing fine movement is generated by arithmetic processing, and
The signal is amplified by 81, 82, and 83, and is applied as a drive voltage and a drive current to the displacement generators 411 and 412 of the actuator 4 and a VCM (not shown). Due to this drive voltage, the displacement generating portion expands or contracts. As a result, as described above, the electromagnetic transducer is in the in-plane direction of the actuator 4, that is, in the XY plane in the drawing, that is, in parallel with the disk medium surface.
Displaces in an arc.

However, actually, the displacement of the electromagnetic transducer may occur vertically in the plane of the actuator 4, that is, also in the floating direction (Z-axis direction). Such a displacement in the floating direction is generated secondarily when the actuator 4 is operated at the time of positioning the electromagnetic transducer. Since the displacement in the flying direction means that the flying height fluctuates and leads to a head crash, it is important to suppress the displacement in the flying direction.

As described above, in the present invention, it is preferable to produce a plate-shaped body of a ceramic piezoelectric / electrostrictive material by a thick film method, fire this, and then form a notch or a hole to produce an actuator. However, in the case where the plate-like body is manufactured by the shape processing, no assembly error occurs. However, even in the actuator manufactured in this way, the shape and material of the displacement generating portion may have variations or asymmetry in a direction perpendicular to the direction in which the displacement generating portion expands and contracts. If there is asymmetry or the like, when the displacement generator expands and contracts, a displacement other than the intended direction may occur. For example, during sandblasting, the photoresist gradually narrows,
Due to the spraying time, spraying angle, hardness difference between the piezoelectric / electrostrictive material layer and the cover part, etc., it is not possible to process the side surface of the displacement generating part so as to be completely perpendicular to the lamination surface. Have difficulty. FIG. 27 shows the displacement generation units 411 and 4 of FIG.
12 is an example of a cross-sectional view in the XZ plane including 12 and, as a result of spraying in the + Z direction by sandblasting, the photoresist gradually narrows, thereby causing the displacement generating portion
An example is shown in which each of the cross sections of 411 and 412 and the fixing portion 43 has a trapezoidal shape.

The displacement generating parts 411 and 412 in FIG. 27 are the displacement parts 411-1 and 412 made of a piezoelectric / electrostrictive material layer having electrode layers on both sides.
-1, a pair of cover portions 411-2 sandwiching the displacement portion 411-1,
411-3 and a pair of cover portions 412- sandwiching the displacement portion 412-1.
2, 412-3. A pair of cover portions (411-2 and 411-3, 412-2 and 412-
In 3), the thickness is the same, but the width is different due to sandblasting. If a voltage is applied to such a displacement generating portion to expand and contract, the width of the upper and lower cover portions sandwiching the displacing portion is different, so that a displacement also occurs in the stacking direction. When one of the displacement generating portions 411 and 412 has a cross-sectional shape as shown in FIG. 27 and one of the displacement generating portions is contracted in the configuration of FIG. 26, the electromagnetic transducer 1 is displaced in the direction of the arrow in FIG. , -Z, that is, the floating direction.

In order to explain the displacement in the floating direction, the position of the electromagnetic transducer 1 when no voltage is applied to the displacement generator is set to 0,
A case is considered in which the electromagnetic transducer 1 is displaced from + L1 to -L2 in the X-axis direction in FIG. 26 by applying a voltage to the displacement generating unit, and this is continuously performed. FIG. 28 shows the relationship between the displacement of the electromagnetic transducer 1 in the X-axis direction and time at this time.

In order to cause the electromagnetic transducer 1 to generate a displacement in the X direction as shown in FIG. 28, consider a case in which voltages are alternately applied to the respective displacement generators. In this case, it is necessary to apply a voltage that shows a temporal change as shown in FIG. 29A to the displacement generating unit 411. On the other hand, it is necessary to apply a voltage that shows a temporal change as shown in FIG. 29B to the displacement generating unit 412. Note that the applied voltage has a positive value when the direction is the same as the polarization direction of the displacement generating portion. When the voltage V1 is applied to the displacement generation unit 411, the electromagnetic conversion element 1 makes a displacement of + L1 in the X-axis direction, and when the voltage V1 is applied to the displacement generation unit 412, the electromagnetic conversion element 1 makes a displacement of -L2 in the X-axis direction. . Therefore, the electromagnetic transducer 1 generates a displacement from + L1 to -L2 in the X-axis direction by the displacement generators 411 and 412 contracting alternately.

Next, the displacement in the Z-axis direction, which is the floating direction, will be considered for each of the two displacement generating units. The temporal change of the voltage applied to the displacement generation unit 411 is shown in FIG. 29A, and the displacement unit 411-1 contracts based on this voltage. On the other hand, since no voltage is applied to the two cover portions sandwiching the displacement portion because they are not sandwiched between the electrode layers, the cover portions do not contract even if they are formed of the piezoelectric / electrostrictive material layer. However, since the cover portion is in close contact with the displacement portion, the cover portion is deformed as the displacement portion contracts. The cover 411-3 shown in FIG. 27 is more easily deformed than the cover 411-2 having a relatively large width. Accordingly, the movable portion 44 is moved to + X with the contraction of the displacement portion 411-1.
The electromagnetic transducer 1 is also displaced in the direction of -Z as a result.
The temporal change of the displacement of the electromagnetic transducer 1 in the Z-axis direction corresponding to the applied voltage shown in FIG. 29A is, for example, as shown in a graph of FIG. 29C. In this graph, the maximum value of the displacement in the -Z direction is Z1. If the difference between the widths of the upper and lower cover parts sandwiching the displacement part is small, Z1 will be small, and if the difference is large, Z1 will be small.
Also increases.

Similarly, the time change of the Z-axis direction displacement of the electromagnetic transducer 1 when the voltage shown in FIG.
It looks like the graph shown in 29D. Here, for example, the difference in width between the cover portions 412-2 and 412-3 in one displacement generating portion 412 is different from the cover portion 411- in the other displacement generating portion 411.
When the difference between the widths 2 and 411-3 is smaller, the maximum value Z2 of the displacement in the -Z direction becomes smaller than the Z1.

Therefore, when the voltage shown in FIG. 29A is applied to the displacement generating unit 411 and the voltage shown in FIG. 29B is applied to the displacement generating unit 412, the temporal change of the Z-axis direction displacement of the electromagnetic transducer 1 becomes
29C and FIG. 29D, that is, the one shown in FIG. 29E. As shown in the drawing, the maximum value of the fluctuation width of the Z-axis direction displacement is Z1.

As described above, the displacement generating section has a displacement section that expands and contracts by applying a voltage, and a pair of cover sections that sandwich the displacement section, and the displacement section and the cover section are perpendicular to the disk medium surface. In the case of a laminated structure, when a voltage is applied to the displacement generating portion to expand and contract, a displacement occurs in the vertical direction, that is, the floating direction, and the displacement also fluctuates. For this reason, the recording / reproducing characteristics deteriorate, and
When the fluctuation range is large, there is a risk of head crash.

Next, a drive control method capable of suppressing the fluctuation width of the displacement in the floating direction will be described.

In the configurations of FIGS. 26 and 27, in order to show the temporal change of the displacement of the electromagnetic transducer 1 in the X-axis direction in FIG.
The displacement of the electromagnetic transducer 1 in the X-axis direction is
Paying attention to the difference in the applied voltage to the displacement generator 411, FIG. 30A shows the temporal change of the applied voltage to the displacement generator 411, and FIG. 30B shows the temporal change of the applied voltage to the displacement generator 412. What is necessary is just to show in FIG. The voltage applied to the displacement generator 411 is obtained by adding a voltage for controlling the amount of displacement (hereinafter, referred to as a control voltage) to the DC bias voltage Vb1, while the voltage applied to the displacement generator 412 is , The control voltage is added to the DC bias voltage Vb2.
In FIG. 30A and FIG. 30B, the control voltage added in the displacement generator 411 and the control voltage added in the displacement generator 412 are set so that the absolute values are always the same and the signs are opposite. That is, the sum of the voltage applied to the displacement generating unit 411 and the voltage applied to the displacement generating unit 412, that is, the total sum of the voltages applied to the displacement generating unit is always a constant value (Vb1 + Vb2).

The DC bias voltage is for preventing the polarization decay of the displacement generating portion as described above.

Next, the displacement in the Z-axis direction, which is the floating direction, is considered by each of the two displacement generating units, as in the previous example. The voltages shown in FIGS. 30A and 30B are applied to the displacement generation units 411 and 412.
Element 1 when individually applied and driven individually
Figure 30C and Figure 30D show the temporal changes of
And The center value of the variation of the displacement in the Z-axis direction is shifted by the displacement amounts Zb1 and Zb2 due to the DC bias voltage, and −Zb1 and −Z
It becomes b2. The variation width of the displacement in the Z-axis direction of each displacement generating unit is Z1 and Z2 corresponding to V1, which is twice the amplitude of the control voltage.
And

Therefore, when the voltage shown in FIG. 30A is applied to the displacement generating unit 411 and the voltage shown in FIG. 30B is applied to the displacement generating unit 412, the temporal change of the Z-axis direction displacement of the electromagnetic transducer 1 is
30C and FIG. 30D, that is, the one shown in FIG. 30E. The fluctuations of the displacements shown in FIG.30C and FIG.30D are only due to the control voltage, and the displacements due to the control voltage cancel each other out because they are in a reverse phase relationship.Therefore, the fluctuation width of the displacement in FIG.30E is Z1 and Z2. The difference is Displacement amplitude
When Z1 / 2 and Z2 / 2 are equal, the fluctuation width is zero. The center value of the displacement variation is the sum of the displacements -Zb1 and -Zb2 generated by the DC bias voltage. DC bias Vb
1 and Vb2 may not be equal, and at least one of them may be zero or a negative voltage. Even in such a case, it is preferable that the voltage be such that polarization decay described above can be prevented.

As described above, when the direction of displacement of the electromagnetic transducer 1 in the Z-axis direction is the same between when the voltage is applied to the displacement generation unit 411 and when the voltage is applied to the displacement generation unit 412, the voltage is applied to the displacement generation unit. By keeping the sum of the applied voltages constant,
The fluctuation width of the Z-axis direction displacement of the electromagnetic transducer 1 can be suppressed.

The displacement of the electromagnetic transducer in the Z-axis direction in the above description is based on the premise that the movable portion will not be twisted when the displacement amount in the Z-axis direction is different between the two displacement generating portions. Actually, in an actuator manufactured by shaping a plate-like body, even when the displacement amount in the Z-axis direction is different between the two displacement generating portions, the movable portion hardly twists. However, even when such a torsion occurs in the movable portion, the effect of the drive control method is realized. In order to reduce the effect of the torsion of the movable part, as shown in FIG.
Is preferably provided substantially at the center of the side surface of the slider 2.

The above description is about the case where the actuator having the cross-sectional shape shown in FIG. 27 is used, that is, the case where the displacement of the electromagnetic conversion element 1 in the Z-axis direction (flying direction) is in the −Z direction. For example, when the spraying direction of the sandblasting is -Z, the trapezoidal shape of the cross section of the displacement generating portion is opposite to that in FIG. 27, and the Z-axis displacement of the electromagnetic transducer is in the + Z direction. However, even in such a case, it is the same that the variation in the displacement in the Z-axis direction can be suppressed by using the above-described drive control method.

In the examples so far, as shown in FIG. 28, it is assumed that the electromagnetic transducer 1 is displaced (oscillated) in the X-axis direction at a constant amplitude and a constant cycle, but the above-described drive control method is used. In this case, it is not necessary to keep the amplitude and the period constant. In an actual HDD, since the electromagnetic transducer is displaced so as to follow a predetermined recording / reproducing track of the disk-shaped medium, the amplitude and cycle of the displacement are not constant.

In the above drive control method, each DC bias voltage Vb1, Vb2
In addition, it is necessary to generate a drive voltage by adding control voltages having the same absolute value and opposite signs.
It can be easily generated by the positioning control circuit 7 and the amplifier 8. Further, in the above drive control method, since only one control signal needs to be processed, there is an advantage that the load on the positioning control circuit 7 can be reduced.

Further, for example, even when an actuator having more than two displacement generating units is used, the above-described drive control method is effective. FIG. 31 shows an example having four displacement generating units. In order to consider the operation, it is sufficient to consider that the displacement generator 411 is divided into 4111 and 4112, and the displacement generator 412 is divided into 4121 and 4122, respectively. First, from the symmetry of the shape, the displacement generator 4111
And 4121 as one pair, and the displacement generation unit 41
12 and 4122 are combined as the other pair, and each pair is considered in the same manner as in the case where there are two displacement generating units. Since the sum of the applied voltages to each pair is constant at any time,
The sum of the voltages applied to the displacement generating section is constant at any time.

If there are more than two displacement generators, the voltage applied to each displacement generator may be different. However, also in this case, in order to suppress the fluctuation of the displacement of the electromagnetic transducer 1 in the floating direction, it is necessary to make the sum of the voltages applied to the respective displacement generating parts constant at any time. When it is considered that the voltage applied in each displacement generating unit is obtained by adding the control voltage to the DC bias voltage, the sum of the control voltages becomes zero.

The number of the displacement generating units is not limited to an even number such as 2 or 4 as shown, but may be an odd number.

The above description is about the case where the directions of the displacements generated in the direction (the Z-axis direction) perpendicular to the direction of expansion and contraction of the displacement generating sections when the voltages of the same polarity are applied to the displacement generating sections 411 and 412 are the same. In this case, the driving control method is most effective. Therefore, if it is inevitable that displacement in the Z-axis direction is generated in the displacement generator, it is preferable to manufacture the actuator so that at least the Z-axis displacement of each displacement generator is in the same direction. When manufacturing an actuator by the method described above, it is difficult to eliminate the displacement of the displacement generating portion in the Z-axis direction.
Managing the direction of axial displacement (Z of both displacement generating parts)
It is easy to make the direction of the axial displacement the same).
That is, as described above, when the plate 4 is formed into a shape by sandblasting to form the actuator 4 shown in FIG. Have substantially the same shape and the same characteristics, the above-described drive control method functions most effectively. In addition, when each displacement generating section is individually manufactured and connected to the fixed section 43 and the movable section 44 by bonding or the like, if the mounting direction is managed, the above-described drive control method can be effectively performed similarly. Can work.

Although the magnetic head having the structure shown in FIG. 26 has been described above, the above-described drive control method is applied to, for example, actuators having the structures shown in FIGS. 3, 6, 8, 9, 10, 11, and 12, respectively. Is also applicable.

Note that, in the configuration shown in FIG.
Even when the direction of the displacement generated in the Z-axis direction of the displacement generating unit when the voltage of the same polarity is applied to the, the fluctuation width of the displacement in the Z-axis direction is increased by using the above-described drive control method. There is no. The direction of the displacement in the Z-axis direction is reversed, for example, when the direction of spraying is different for each displacement generating part during the sandblasting described above. In addition, when each of the displacement generating portions is individually manufactured and connected to the fixed portion 43 and the movable portion 44 by bonding or the like, even when the mounting directions are different between the two displacement generating portions, the Z-axis direction May be reversed. Hereinafter, a case will be described in which the above-described drive control method is applied to an actuator in which the directions of displacement in the Z-axis direction of the two displacement generating units are opposite to each other.

In this case, when the voltage shown in FIG. 29A is applied to the displacement generating unit 411 and the voltage shown in FIG. 29B is applied to the displacement generating unit 412, the variation width of the displacement of the electromagnetic transducer 1 in the Z-axis direction becomes The sum (Z1 + Z2) of the maximum values of the displacement in the Z-axis direction when a voltage is applied to the generator.

Further, when the voltage shown in FIG. 30A is applied to the displacement generation unit 411, and the voltage shown in FIG. 30B is applied to the displacement generation unit 412,
The variation of the Z-axis direction displacement of each displacement generating unit is generated by the control voltage, and the Z-axis direction displacement of both displacement generating units is in phase. Therefore, the variation width of the Z-axis direction displacement of the electromagnetic transducer 1 is This is the sum of the variation widths of the displacements when voltages are individually applied to the displacement generating units.

That is, when the directions of the Z-axis direction displacement due to the application of the same polarity voltage are different between the two displacement generating units, the Z of the electromagnetic transducer 1 when the drive voltage is alternately applied to each displacement generating unit.
The maximum value of the fluctuation width of the axial displacement is the same as the maximum value of the fluctuation width of the Z-axis displacement when the total sum of the driving voltages applied to the displacement generator is kept constant. Therefore, in any case, the maximum value of the fluctuation width of the Z-axis direction displacement is not increased by the above-described drive control method that keeps the total sum of the drive voltages applied to the displacement generators constant.

Experimental example of drive control method PZT (piezoelectric constant d ₃₁ = −250 × 10) as piezoelectric / electrostrictive material
With ^-12 m / V), by using the above-described thick film method to prepare the actuator structure shown in FIG. 26.

The piezoelectric / electrostrictive material layer had a thickness of 20 μm, and was a 10-layer laminate (0.2 mm in total thickness) of 8 layers sandwiched between electrode layers on both sides and one upper and lower layer serving as a cover. The displacement generator is 1 mm long,
The thickness is 0.2 mm, the cross section is trapezoidal, and the width of the cover is
The narrow one was 0.05 mm, the wide one was 0.15 mm, the pitch between both displacement generating parts was 0.2 mm, and the displacement generating parts were polarized.

When a voltage of 20 V is applied to one of the displacement generating portions of the actuator in the same direction as the polarization direction, the displacement generating portion shrinks by about 0.2 μm, and the X
The axial displacement was about 0.5 μm. Then, when a voltage of 0 to 20 V with a half-wave sine wave was alternately applied to both displacement generating portions, the displacement of the movable portion in the X-axis direction was ± 0.5 μm, and Z
The variation width of the axial displacement was about 0.1 μm.

On the other hand, when a voltage in which sine waves having an amplitude of 10 V and phases opposite to each other were superimposed on a DC bias of 10 V was applied to the two displacement generating portions, the displacement of the movable portion in the X-axis direction was ±±.
At 0.5 μm, the fluctuation width of the displacement in the Z-axis direction could be suppressed to 0.01 μm or less (less than the measurement limit).

From these results, it is clear that the effect of making the sum of the voltages applied to the respective displacement generating parts constant at any time when driving the actuator is obtained.

Continuation of front page (72) Inventor Yutake Sato 1-13-1 Nihonbashi, Chuo-ku, Tokyo Inside TDK Corporation (56) References JP-A-10-293979 (JP, A) JP-A-10-293975 ( JP, A) JP-A-9-73746 (JP, A) JP-A-6-259905 (JP, A) JP-A-6-20415 (JP, A) JP-A-5-47124 (JP, A) JP-A-5-28670 (JP, A) JP-A-4-286787 (JP, A) JP-A-2-227886 (JP, A) International Publication 93/2451 (WO, A1) (58) Fields investigated (Int. Cl. ⁷ , DB name) G11B 21/10 G11B 21/02 G11B 21/21 G11B 7/09

Claims (17)

(57) [Claims] An actuator includes a slider provided with an electromagnetic transducer or an optical module, an actuator, and a suspension. The slider is supported by the suspension via the actuator, and the actuator connects the fixed part, the movable part, and these. At least two beam portions are provided, and at least one of the beam portions is provided with a displacement generating portion, and the displacement generating portion expands and contracts in a direction connecting the fixed portion and the movable portion by an inverse piezoelectric effect or an electrostrictive effect. The fixed portion is fixed to the suspension and the movable portion is fixed to the slider, and the displacement generating portion is bent and the movable portion is linearly or arc-displaced with respect to the fixed portion as the displacement generating portion expands and contracts. Along with the rotational displacement, a linear or arc-shaped locus is formed so that the electromagnetic transducer or the optical module intersects the recording track of the recording medium. The fixed portion, the movable portion, and the beam portion are integrally formed by providing a hole and / or a notch in a plate-shaped body made of a piezoelectric / electrostrictive material. A recording / playback head. 2. The recording / reproducing head according to claim 1, wherein the actuator is disposed on a rear surface or a side surface of the slider. 3. The recording / reproducing head according to claim 2, wherein the actuator is arranged in a space formed by a step provided on the back surface of the slider. 4. The recording / reproducing head according to claim 1, wherein the slider and the actuator are arranged to face each other across the suspension. 5. A suspension according to claim 1, further comprising a gimbal portion for causing the slider to follow the surface of the recording medium, and an actuator connected to the gimbal portion. The recording / reproducing head according to any one of the above. 6. The recording / reproducing apparatus according to claim 1, wherein at least two piezoelectric / electrostrictive material layers having electrode layers on both sides thereof are present in the displacement generating portion of the actuator. head. 7. The recording / recording apparatus according to claim 1, wherein a displacement amount of the electromagnetic transducer or the optical module is larger than a displacement amount of a displacement generating portion of the actuator.
Playhead. 8. The recording / reproducing head according to claim 7, wherein a displacement of the electromagnetic transducer or the optical module is larger than a displacement of a connecting portion between the slider and the actuator. 9. The recording / reproducing head according to claim 7, wherein a displacement amount of a connecting portion between the slider and the actuator is larger than a displacement amount of a displacement generating portion of the actuator. 10. The recording / reproducing head according to claim 1, wherein wiring to the actuator and / or the electromagnetic transducer or the optical module is formed on the suspension. 11. A recording / reproducing head positioning mechanism comprising: the recording / reproducing head according to any one of claims 1 to 10; and a main actuator for driving the entire recording / reproducing head. 12. A mechanism having a slider on which an electromagnetic transducer or an optical module is provided, an actuator, and a suspension, wherein the slider positions a recording / reproducing head supported by the suspension via the actuator. Has a fixed portion, a movable portion, and at least two beam portions connecting them, at least two displacement generating portions of the beam portion are formed, and the displacement generating portion is a fixed portion by an inverse piezoelectric effect or an electrostrictive effect. The movable part is fixed to the suspension, the movable part is fixed to the slider, and the movable part is bent and the movable part is fixed as the displacement generating part expands and contracts. The electromagnetic transducer or the optical module can record linearly, arcuate, or rotationally with respect to the recording medium. It is displaced by drawing a linear or arc-shaped trajectory so as to intersect with the rack.When positioning in the direction intersecting with the recording track, the total sum of the drive voltages applied to each displacement generating part is determined at any time. A recording / reproducing head positioning mechanism for controlling the recording / reproduction head to be constant. 13. The direction of expansion and contraction of each displacement generating section is the same for an applied voltage of the same polarity, and the voltage applied to each displacement generating section is obtained by adding a control voltage to a DC bias voltage. 13. The recording / reproducing head positioning mechanism according to claim 12, wherein the sum of the control voltages added in each displacement generating section is controlled to be zero at any time. 14. Each of the displacement generating sections has a displacement section that expands and contracts by applying a voltage, and a pair of cover sections sandwiching the displacement section, wherein the displacement section and the cover section are perpendicular to the surface of the recording medium. 14. The recording / reproducing head positioning mechanism according to claim 12, wherein the recording / reproducing head is laminated, and the cover part is in close contact with the displacement part, and is deformed as the displacement part expands and contracts. 15. The recording / reproducing head according to claim 1,
15. The recording / reproducing head positioning mechanism according to any one of claims 12 to 14, which is the recording / reproducing head according to any one of claims to 10. 16. The recording / reproducing head positioning mechanism according to claim 12, further comprising a main actuator for driving the entire recording / reproducing head. 17. A recording / reproducing head according to any one of claims 1 to 10, or a recording / reproducing head according to claims 11 to 16.
A recording / reproducing apparatus having the recording / reproducing head positioning mechanism according to any one of the above items.