JP2001126422A - Head positioning mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a head positioning mechanism suitable for mass production by realizing high speed and high resolution access. SOLUTION: A head positioning mechanism part having a suspension arm rocked by a main actuator interposed in the radial direction of a disk memory medium is newly provided with a finely positioning mechanism where at least, two beam parts 43 are plate-like matter consisting of piezoelectric elements 41 and the plate-like matters constitute two walls in parallel in the longitudinal direction of the suspension arm 5 provided with a head part. In this finely positioning mechanism, the rocking movement of movable part connected to the parts 43 is generated from the control of applying to the elements 41 constituting the parts 41, thereby the head part can be moved by a finely displacing quantity. Thus, positioning of the fine/rough movement of the head part can be controlled, thereby high speed and high resolution are easily realized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positioning mechanism and a storage device, and more particularly, to a fine positioning mechanism and a storage device capable of realizing high-speed and high-resolution access and suitable for mass production.

[0002]

2. Description of the Related Art A conventional storage device, for example, a magnetic disk device 700 as shown in FIG.
01, a floating head mechanism 703 provided with a magnetic head 702, a carriage 705 supported by a swing shaft 704 to mount the floating head mechanism 703, and a voice coil motor 706 provided on the opposite side of the magnetic head 702. Have. By energizing the voice coil motor 706, the magnetic head 702
Swings. The magnetic head 702 flies above the rotating magnetic disk 707.

At present, the recording density per unit area in a storage device is increasing at an accelerated rate. Accordingly, a head positioning mechanism that enables high-speed and high-resolution access is required. In response to these requirements, for example, a technique for reducing the translational force acting on the pivot shaft by using two voice coil motors, and a technique using a two-stage actuator for coarse movement and fine movement have been developed.

[0004]

However, in realizing high-speed and high-resolution access, the conventional storage device 700 has a problem in that the entire device vibrates due to a seek reaction force, and seek time is increased. is there.
In general, a storage device switches between a seek control system and a following control system in order to realize high-speed seek and high-precision following. However, there is a problem that a time loss occurs due to the switching of these control systems, and the positioning time increases.

In order to solve the above problems, a piggyback type magnetic disk having a voice coil motor provided between a suspension arm and a carriage has been proposed (International Conference on Mic).
romechatronics for Information and Precision
Equipment, Tokyo, July, 20-23, 1997: MR-08 DEVELOPME
NT OF INTEGRATED PIGGYBACK MILLI-ACTUATOR FOR
HIGH DENSITY MAGNETIC RECORDING: Shinji KOGA
NEZAWA etc FUJITSU LIMITED).

FIG. 10 shows the structure of the magnetic disk drive. In this magnetic disk drive 800, the carriage 8
In this configuration, a voice coil motor 803 for positioning is provided between the suspension arm 801 and the suspension arm 802. A stator shaft 804 is attached to one end of the carriage 801. The carriage 801 has a magnet 80
5 is fixed. Further, a coil 806 is arranged so as to face the magnet 805. Coil 806
Are fixed to the head mounting block 807. The head mounting block 807 includes a cross-shaped spring 8 of the suspension arm 802.
08. Cross shaped spring 80
8 is made of an extremely thin steel plate. A stator shaft 804 is spot-welded at the center of the cross-shaped spring 808. At the tip of the suspension arm 802, a gimbal 809 is formed. A slider (not shown) provided with a magnetic head is attached to the lower surface of the gimbal 809. In the magnetic disk device 800, the seek time is reduced by the short seek operation by the voice coil motor 803.

However, the above-mentioned conventional magnetic disk drive has a structure in which the entire structure having a large mass consisting of a magnetic head, an arm and a coil is swung, and a structure in which a slider is moved via an elastic suspension. In addition, since the bearing which is the center of swing always has friction resistance, eccentricity, and the like, there is a problem that positioning accuracy, particularly tracking track tracking accuracy, is limited. Further, the magnetic disk drive 800 has a problem that it has a large number of parts, is complicated and delicate, and is not easy to assemble and adjust, so that it is not suitable for mass production. In addition, in the magnetic disk drive 800, the head mounting block 807 and the suspension arm 80
Since 2 is a movable portion, the mass tends to increase and the seek reaction force tends to increase. For this reason, there is a problem that there is a limit in reducing the seek time. Further, in the actuator using the electromagnetic force, there is a concern that the leakage magnetic flux may affect the magnetic signal of the disk-shaped storage medium.

On the other hand, in a conventional optical disk device,
In general, the optical pickup uses an optical pickup provided with an optical module having at least a lens. In this optical pickup, an actuator is configured around the lens so that the recording surface of the optical disc is focused, and control is performed. However, a flying slider is used in near field recording, which has recently been proposed as a method for dramatically increasing the recording density of an optical disk. This flying type slider is an SIL (solid immersion)
An optical module having a hemispherical lens called a lens, a magnetic field modulation recording coil, and a prefocus lens is incorporated in a slider shape, and a slider similar to a floating magnetic slider is used. An optical disk used in combination with such a flying slider has an extremely high recording track density, so that when positioning the disk-shaped storage medium with respect to the recording tracks, the same problems as those of the floating magnetic slider described above occur. .

SUMMARY OF THE INVENTION It is an object of the present invention to provide a recording / reproducing apparatus such as a magnetic disk apparatus or an optical disk apparatus for positioning an electromagnetic transducer or an optical module provided on a recording / reproducing head with high accuracy and high speed. It is an object of the present invention to provide a minute positioning mechanism and a storage device suitable for mass production.

[0010]

In order to achieve the above object, a first storage device according to the present invention comprises an electromagnetic conversion element or an optical module for recording data and reproducing the data recorded on a storage medium. In a slider-shaped head portion provided and a head positioning mechanism portion via a suspension arm that swings by a main actuator in a radial direction of the disk-shaped storage medium, the suspension arm that swings the slider. A movable portion for holding the movable portion and a fixed portion on the side having the swing support portion, at least two beam portions connecting these are plate-like bodies made of a piezoelectric / electrostrictive material; On the other hand, the minute positioning mechanism is constituted by a structure in which the beam portion of the plate-like body has a double wall as a parallel spring structure. At least one of the beam portions provided in the minute positioning mechanism enables a minute swinging movement of the suspension arm movable portion holding the head portion by an inverse piezoelectric effect or an electrostrictive effect.

When a specific voltage is applied to the piezoelectric body, distortion occurs due to the inverse piezoelectric effect, and the piezoelectric body itself expands and contracts.
At least two beam portions provided with the piezoelectric body perform bending displacement for bending the longitudinal end of the beam portion in accordance with expansion and contraction of the piezoelectric body. Further, since the beam portion forms a parallel spring structure that connects the fixed portion side and the movable portion side of the suspension arm, a minute swinging motion of the movable portion is enabled by controlling the application of the piezoelectric body provided in the beam portion. Therefore, a slider-shaped head having an electromagnetic conversion element or an optical module function provided at the tip of the movable portion of the suspension arm is:
By controlling the application to the piezoelectric body provided in the beam portion, fine positioning of the head can be easily performed.

In order to achieve the above object, a second storage device according to the present invention drives a head unit using a magnetic circuit and a coil provided on a fixed side of a suspension arm in a head positioning mechanism unit. And a micro-positioning mechanism that includes a piezoelectric / electrostrictive element and drives the head from application control. The main actuator positioning mechanism drives the head using a magnetic circuit and a coil, and is suitable for large movement.

The minute positioning mechanism is suitable for minute movement because the head is driven by expansion and contraction of the piezoelectric body. By using these main actuator positioning mechanisms and minute positioning mechanisms, the seek operation and the following operation can be performed efficiently. For example, seek operation is performed by the main actuator positioning mechanism,
The following operation is performed by a minute positioning mechanism. Also, the seek operation or the following operation may be performed by using both the positioning mechanism of the main actuator and the minute positioning mechanism. Furthermore, since control is performed using two actuators, a main actuator positioning mechanism and a minute positioning mechanism, there is no need to switch between seek control and following control. Also,
Since the fine positioning mechanism is integrated with the suspension arm, the mass of the movable portion is small, and the seek reaction force can be suppressed to a small value. Further, since a piggyback type arm can be configured with a very simple structure, it is suitable for mass production.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. The present invention is not limited by the embodiment. FIG. 1 is a perspective view showing a magnetic disk drive according to an embodiment of the present invention. The magnetic disk device 100 includes a spindle mechanism 1 for rotating a magnetic disk, and a main actuator positioning mechanism 2 for positioning a magnetic head. The spindle mechanism 1 and the positioning mechanism 2 are incorporated in a base 3.

The spindle mechanism 1 has a structure in which a magnetic disk 11 is bolted to a rotating shaft 12 of a DC motor incorporated in a base 3. The magnetic disk 11 has a magnetic recording layer formed by applying an oxide on the disk base surface,
Any of magnetic materials sputtered may be used. It is preferable that the magnetic layer of the magnetic disk 11 be thin and have high coercive force, and that the magnetic material particles be fine and the surface be uniform.

The carriage 21 is rotatably supported by a swing shaft 22. The end of the carriage 21 has a rotor 2
3 is attached. The rotor 23 forms a voice coil motor 25 together with the stator 24 provided on the base 3 side. The rotor 23 has a configuration in which a movable coil is bonded to upper and lower surfaces of a carriage plate. The stator 24 is formed of a permanent magnet, and is arranged so as to sandwich the rotor 23.
The movable coil has a flexible cable 26.
Power is supplied via the. The base 3 has a circuit board 2
7, a seek / following control unit 28 is formed on the circuit. The suspension arm 5 is connected to an end of the carriage 21, and a positioning mechanism 4 is further provided.

FIG. 2 is an assembly view showing the minute positioning mechanism 4. The suspension arm 5 is divided into a movable portion that holds a slider having a fixed portion on the swing support shaft side and a head portion. At least two beam portions 43 are formed of a plate-shaped body made of a piezoelectric / electrostrictive material and an elastic material, and are configured to connect the suspension arms 5. The suspension arm 5 shown in the figure is an example in which a parallel spring structure is formed in the longitudinal direction and integrated. The beam portion 43 includes a piezoelectric element 41 and an elastic support 42, and has a structure in which elastic deformation having a degree of freedom in the longitudinal direction is performed according to a bending force and a bending displacement amount of the piezoelectric element 41. The suspension arm 5 is formed from a sheet metal, for example, a stainless material or a beryllium material by using a photofabrication technique such as etching. By using the non-machining process, the shape accuracy is improved, and the deformation stress and the mechanical stress generated at the time of working formation can be eliminated, and the function and reproducibility are stabilized. Further, the suspension arm 5 shown in FIG. 2 has a central portion bent by a mold to form connecting portions on both side surfaces in the longitudinal direction. A gimbal 51 is formed at the tip of the suspension arm 5, and a slider having a head function is attached to the gimbal 51.

The piezoelectric element 41 is bonded to the beam 43. The piezoelectric element 41 is a material exhibiting a characteristic that a stress or a displacement is generated according to the applied voltage, a resonance phenomenon is generated according to the frequency of the applied voltage, and a voltage is generated according to the applied pressure. The piezoelectric element 41 of the present example is bonded to the elastic support plate 42 by using a thin film of a thin film of lead zircon titanate having a high piezoelectric constant in a rectangular shape by dicing. The piezoelectric element 41 may use barium titanate, lithium niobate, lead zircon titanate, or the like. Instead of these piezoelectric ceramics, a functionally graded material or lithium niobate can be used.

The bonding interface at the time of bonding the elastic support plate 42 and the piezoelectric element 41 is required to be very thin and hard, tough, and that the resistance value near the resonance frequency after bonding is small. . For example, a polymer adhesive represented by hot melt and epoxy resin is used as the adhesive. The provided beam portion 43 shown in FIG. 2 is a unimorph type, but may be a bimorph type using two piezoelectric elements, a multimorph type using four or more piezoelectric elements, or a laminated type. Further, the shape of the beam portion 43 is not limited to the shape in which the mouth shapes are arranged as shown in FIG.

The power supply supplies power to the piezoelectric element 41 via a wiring. In the seek / following control, the supply voltage is controlled based on a servo signal from a magnetic head. Ferrite head, M
IG (Metal In Gap) head, thin film head, MR (Ma
gneto Resistive) head, GMR (Giant Magneto)
Resistive) A slider using any of the heads is preferable.
Further, instead of the magnetic head, a module for recording / reproducing an optical disk, for example, a head slider using near-field light may be used.

Next, the operation of the magnetic disk drive 100 will be described. First, the principle of bending displacement of the piezoelectric element 41 is shown in FIG. The inverse piezoelectric effect used herein is a phenomenon in which a distortion is generated when a voltage is applied to a piezoelectric body, and the piezoelectric body expands and contracts. In FIG. 3, the beam 4 shown in FIG.
This is used as an example showing the same behavior as that of No. 3, and has a cantilever structure including a fixed end side and a free end side. This cantilever is joined to the piezoelectric element by using an elastic material as a reinforcing material. When an electric field is applied in the opposite direction to the polarization direction of this piezoelectric body, when one piezoelectric body extends in the length direction,
The other shrinks and bends in the thickness direction around the reinforcing material. FIG. 3 shows a state in which a given applied voltage is applied to cause bending on the free end side of the beam portion and generate bending displacement d at the longitudinal end.

As in the behavior shown in FIG. 3, the beam portion 43 in FIG. 2 performs a swinging motion from the fixed portion of the suspension arm 5 to the movable portion (the side supporting the slider) at the other end. Becomes Further, since the beam portion 43 is configured to have a parallel spring structure with respect to the movable portion, the movable portion of the suspension arm 5 and the slider held by the beam can be stably moved in parallel to the left and right by minute control by application control. The configuration is such that a displacement amount can be obtained.

The solution of the displacement d at the tip of the beam obtained from the general formula is a piezoelectric constant d31, an applied voltage v, and an effective length l of the beam.
And the constant k, and is inversely proportional to the square of the thickness t of the beam portion. From this, in the minute positioning mechanism according to the present invention, the sensitivity of the displacement to the applied voltage is obtained from the characteristics of the piezoelectric body and the shape of the elastic support, and the displacement is controlled by the applied voltage. In order to obtain a displacement at a low voltage, it is necessary to use a piezoelectric element having a large piezoelectric constant d31. As a structure of the minute positioning mechanism, the thickness of the piezoelectric element should be reduced or the effective length in the longitudinal direction in consideration of the resonance frequency. It is necessary to determine whether the length is longer according to a desired specification.

In this embodiment, the piezoelectric body has a rectangular shape with a thickness of 0.05 to 0.3 mm, a longitudinal direction of 1 to 5 mm, and a width orthogonal to the longitudinal direction of 0.1 to 0.5 mm. And the piezoelectric constant is 100 to 600 × 10 ^{-12 at} d31.
Use specifications with m / v as a guide. Further, the selection was made in consideration of the material characteristics that become stable with respect to temperature and electric field and the change with time. Therefore, a moving distance of 0 to 1 μm can be obtained in the movable portion of the suspension arm 5 according to the input voltage, and a high positioning resolution of sub-μm can be obtained by application control.

Next, the operation of the voice coil motor 25 will be described. FIG. 5 is an explanatory diagram showing the operation principle of the voice coil motor 25. By flowing a current in the direction of arrow I through the movable coil (23), a force f (arrow F) is generated according to Fleming's left-hand rule. Positioning control
By controlling the direction and magnitude of the current flowing through the movable coil (23), positioning is performed in submicron units at a target position.

Usually, positioning control in a magnetic disk drive is performed by access speed control (seek control) and follow-up positioning control (following control). In the access speed control process, the magnetic head is moved at high speed from the current track to the target track. In the following positioning control process, the magnetic head is made to precisely follow the track. FIG. 6 is a graph showing the relationship between the access movement speed of the magnetic head and time. Thus, the positioning control can be temporally divided into an access speed control process and a follow-up positioning control process.

In the magnetic disk drive 100, the access speed control and the follow-up positioning control are performed in parallel, the access operation is performed at high speed mainly using the voice coil motor 25, and the follow-up positioning operation is mainly performed. It is performed precisely using the minute positioning mechanism 4. FIG. 7 shows a block diagram of the positioning control system. The seek / following control unit 28 performs seek control and following control in parallel. In the seek control system, first, the current head position is detected, and then the operation amount is obtained based on the detected head position. The phase compensator controls the phase of the signal of the operation amount. The power amplifier amplifies the signal of the operation amount controlled by the phase controller. Then, the voice coil motor 25 is driven according to the operation amount.
The control amount of the seek control system is converted into a signal of the same type as the target value signal, and is fed back to the input side.

On the other hand, in the following control system,
First, a track error signal is detected, and then an operation amount is obtained from the detected track error signal. The phase compensator controls the phase of the signal of the operation amount. The power amplifier amplifies the signal of the operation amount controlled by the phase controller. Then, it applies and drives the piezoelectric body 41 of the minute positioning mechanism 4 according to the operation amount of the track error signal. The control amount of the following control system is converted into a signal of the same type as the target value signal, and is fed back to the input side.

FIG. 8 is a flowchart showing an example of a control process by the seek / following control unit 28.
In step S1101, a target track position is input. In step S1102, the voice coil motor 25
Is turned on, and positioning control is performed based on the input data of the target track position. In step S1103, it is determined whether or not the difference between the head position and the target track position is less than the movable distance of the beams 51 and 52 (the range in which positioning by the beams 51 and 52 is effective). The positioning control by the voice coil motor 25 is performed until the distance becomes less than the movable distance. If the distance is less than the movable distance, the process proceeds to step S1104.

In step S1104, the positioning control system by the minute positioning mechanism 4 is turned on. Step S11
At 05, the positioning control is performed by both the piezoelectric body 41 of the minute positioning mechanism 4 and the voice coil motor 25 until the difference between the head position and the target track position becomes smaller than the width of one to three tracks. The reason why the voice coil motor 25 is used together is that relatively large movement such as movement between tracks is included. In step S1106, the positioning control system by the voice coil motor 25 is turned off, and the positioning control is performed only by the minute positioning mechanism 4. Step S
At 1107, it is determined whether or not the difference between the head position and the target track position satisfies the track positioning accuracy. Control is continued until the condition is satisfied, and when the condition is satisfied, the positioning control system of the minute positioning mechanism 4 is turned off (step S110).
8).

The sharing between the voice coil motor and the minute positioning mechanism 4 is clearly divided, the access operation is performed at a high speed using the voice coil motor 25, and the following positioning operation is performed by the swing movement of the minute positioning mechanism 4. It may be performed precisely by using this. Next, FIG. 4 shows another assembly example of the minute positioning mechanism. The suspension arm 5 is divided into a fixed part and a movable part as in FIG. 2, but the configuration of the beam part to be connected is different. The beam portion 43 has a configuration including the piezoelectric element 41 and the elastic support 42, and one of the elastic supports 4
A single-layer beam portion 44 having a configuration of 2 was provided.

This is an example of a configuration in which the entire frame of the suspension 5 is reinforced against disturbances generated in the suspension arm 5 when the recording apparatus is moving, for example, pitching, yawing and rolling of a slider having a head function.

[0033]

As described above, the present invention relates to a slider-shaped head provided with an electromagnetic transducer or an optical module for recording data and reproducing data recorded on a storage medium, and a disk-shaped storage medium. In a head positioning mechanism section via a suspension arm that swings by a main actuator in the radial direction, the suspension arm that swings is a side having a movable section that holds the slider and the swing support section. At least two beam portions connecting the fixed portions are plate-like members formed of a piezoelectric / electrostrictive material and an elastic body, and at least the two beam portions are arranged in a longitudinal direction of the suspension arm.
The two beam portions are formed of a parallel spring structure that constitutes a double wall in parallel, and at least one of the beam portions is capable of performing a minute swinging motion with respect to the fixed portion due to an inverse piezoelectric effect or an electrostrictive effect. The seek operation and the following operation can be efficiently performed by the minute positioning mechanism described above.

Further, the fine positioning mechanism enables fine movement of the head provided at the tip of the suspension arm, so that the head positioning accuracy is improved. Further, since it is not necessary to switch between the seek control and the following control, the time loss due to the switching can be reduced. As described above, high-speed and high-resolution access of the head can be realized. Further, since the suspension arm can be configured with a minimum number of parts with a relatively simple configuration, the suspension arm is suitable for mass production.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a minute positioning mechanism according to an embodiment of the present invention.

FIG. 2 is an assembly view showing a part of the minute positioning mechanism shown in FIG.

FIG. 3 is an explanatory diagram showing an example in which a free end (movable portion) swings due to bending of a beam portion.

FIG. 4 is another assembly view showing a part of the positioning mechanism.

FIG. 5 is an explanatory diagram showing the operation principle of the voice coil motor.

FIG. 6 is a graph showing a relationship between an access movement speed of a magnetic head and time.

FIG. 7 is a block diagram of a minute positioning control system.

FIG. 8 is a flowchart illustrating an example of a control process performed by a seek / following control unit.

FIG. 9 is a perspective view showing an example of a conventional magnetic disk drive.

FIG. 10 is a perspective view showing another example of a conventional magnetic disk drive.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 magnetic disk drive 1 spindle mechanism 2 positioning mechanism 21 carriage 22 oscillating shaft 23 rotor 24 stator 25 voice coil motor 26 flexible cable 27 circuit board 28 seek / following control unit 3 base 4 minute positioning mechanism 41 piezoelectric element 42 elastic support 43 Beam section 44 Single layer beam section 5 Suspension 51 Gimbal 700 Conventional storage device 701 Suspension arm 702 Magnetic head 703 Floating head mechanism 704 Swing axis 705 Carriage 706 Voice coil motor 707 Magnetic disk 800 Magnetic disk device 801 Carriage 802 Suspension arm 803 Voice coil motor 804 Stator shaft 805 Magnet 806 Coil 807 Head mounting block 808 Cross E type de spring 809 gimbal

Continuation of the front page (72) Inventor Seiji Watanabe 1-8-1, Nakase, Mihama-ku, Chiba-shi, Chiba Prefecture Inside Seiko Instruments Inc. (72) Inventor Takeshi Suzuki 1-8-8, Nakase, Mihama-ku, Chiba-shi, Chiba Seiko Instruments Incorporated (72) Inventor Yoko Suzuki 1-8 Nakase, Mihama-ku, Chiba-shi, Chiba F-term (reference) in Seiko Instruments Inc. 5D042 LA01 MA15 5D059 AA01 BA01 CA08 DA11 EA08 EA12 5D096 NN03 NN07 5H303 AA17 BB01 CC01 DD01 DD14 DD21 EE03 EE07 FF03 HH02 KK35

Claims (2)

[Claims] 1. A slider-shaped head provided with an electromagnetic transducer or an optical module for recording data and reproducing the data recorded on the storage medium, and an actuator mainly arranged in a radial direction of the disk-shaped storage medium. In a head positioning mechanism section via a swinging suspension arm, the swinging suspension arm comprises a movable section for holding the slider and a fixed section on the side having the swing support section, and at least these are connected to each other. A parallel spring structure in which the two beam portions are plate-like bodies made of a piezoelectric / electrostrictive material and an elastic material, and at least the two beam portions are in parallel with each other in a longitudinal direction of the suspension arm. The movable part is small relative to the fixed part due to an inverse piezoelectric effect or an electrostrictive effect. A micro-positioning mechanism, which enables a simple swinging motion. 2. A recording / reproducing apparatus comprising the minute positioning mechanism according to claim 1.