JPH0973746A - Disk device head support mechanism - Google Patents

Abstract

The present invention relates to a head support mechanism of a disk device, and an object of the present invention is to provide a head support mechanism capable of highly accurate and efficient minute displacement for tracking correction of the head. . A head 22 for recording / reproducing on / from a disk and a load beam 18 on which the head 22 is mounted
And two piezoelectric elements 36, 38, 40, 42 provided on the front and back of the load beam 18, respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to a disk device such as a magnetic disk device suitable for high-density recording, and more specifically, to a head for recording and / or reproducing data on the disk in the disk device. Regarding the support mechanism.

In recent years, a magnetic disk device provided with one or a plurality of magnetic disks that are rotationally driven as a data recording medium has been widely used for applications such as an external storage device of a computer. The recording density of magnetic disk devices has been increasing year by year with the adoption of MR heads (recording / reproducing heads having a magnetoresistive effect type head as a read-only head), and the like It has reached the limit to perform tracking only by an electromagnetic actuator. Therefore, a large number of magnetic disk devices have been provided which employ a head support mechanism having a minute displacement mechanism of the head to perform tracking correction.

[0003]

2. Description of the Related Art FIG. 1 is a plan view showing an example of a conventional head support mechanism of a magnetic disk device. A head 2 that records / reproduces data on / from a magnetic disk (not shown) that is rotationally driven is temporarily supported by a suspension arm 4, and the other end of the suspension arm 4 is within a minute angle range around a protrusion 8 of a carriage 6. It is rotatably supported by.

The carriage 6 is rotatable about a shaft member 10 fixed to the housing of the magnetic disk device, and a magnetic circuit 12 fixed to the housing side with respect to a permanent magnet (not shown) fixed to the carriage 6. The carriage 6 rotates with respect to the shaft member 10 by controlling the exciting current flowing through the drive coil 14, which is a part of the magnetic head, so that the head 2 can be moved in the substantial radial direction of the magnetic disk. Has become.

A piezoelectric element 16 is interposed between the carriage 6 and the suspension arm 4. By extending and contracting the piezoelectric element 16 in the direction of the arrow in the drawing, the suspension arm 4 is within a minute angle range with respect to the carriage 6. The head 2 is rotated, and the head 2 is slightly displaced.

[0006]

In the conventional structure shown in FIG. 1, the piezoelectric element 16 has its longitudinal ends in contact with the suspension arm 4 and the carriage 6, respectively. Since the head 2 is slightly displaced, the piezoelectric element 16
There is a problem that the head 2 cannot be efficiently displaced minutely with respect to the voltage applied to the head.

Therefore, an object of the present invention is to provide a head support mechanism of a disk device capable of highly accurate and efficient minute displacement for tracking correction of the head.

[0008]

According to the present invention, there is provided a head for reproducing at least data on a rotationally driven disk, and a plate-like elastic body having a first end and a second end. The head is mounted on the end, and the second
The ends are a load beam rotatably supported for moving the head in a substantially radial direction of the disk, and first and first ends provided on one surface of the load beam substantially parallel to each other in the longitudinal direction. A second piezoelectric thin film, and third and fourth piezoelectric thin films provided on the other surface of the load beam so as to be substantially parallel to each other in the longitudinal direction and to face the first and second piezoelectric thin films, respectively. A head support mechanism of a disk device is provided, which includes first to fourth piezoelectric thin films and first to fourth electrode pairs for applying a voltage in the thickness direction thereof.

According to this configuration, for example, the first and third
The first to second piezoelectric thin films and the second and fourth piezoelectric thin films expand and contract in phase with each other, and the first and second piezoelectric thin films and the third and fourth piezoelectric thin films expand and contract with opposite phases, respectively. By applying a voltage signal to the fourth electrode pair, it is possible to perform highly accurate and efficient minute displacement for tracking correction.

Further, the first and second piezoelectric thin films and the third and fourth piezoelectric thin films expand and contract in phase with each other, and the first and third piezoelectric thin films and the second and fourth piezoelectric thin films respectively expand and contract. By applying a voltage signal to the first to fourth electrode pairs so as to expand and contract in the opposite phase, it is possible to perform highly accurate and efficient minute displacement in the direction toward the magnetic disk surface of the head.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below. FIG. 2 is a perspective view of the embodiment of the head support mechanism of the present invention viewed from the magnetic disk side. A gimbal 20 is formed by punching or the like on one end side of the load beam 18 having a substantially rectangular shape made of a plate-like elastic body such as a stainless steel plate, and a head 22 is mounted on the gimbal 20.

The head 22 is floated at a predetermined distance from the magnetic disk that is driven to rotate so that the head 22 can fly.
Four. On the end surface of the slider 24, a head portion 26 including an MR element and a plurality of (four in this example) terminals 27 for connecting the head portion 26 to an external circuit are formed. On the bottom surface of the slider 24, rails 28 and 30 having a predetermined shape are formed in order to generate an appropriate air flow with the rotating magnetic disk.

The head beam 18 is formed of a plate-like elastic body in order to balance the elastic force with the flying force of the slider 24 to obtain the required flying height of the head 22. For adjustment, bent portions 18A are formed on both sides of the load beam 18.

The four terminals 27 of the head 22 are connected to the signal patterns 32A, 32B,
32C and 32D are respectively connected by ball bonding. Signal patterns 32A, 32B, 32C
And 32D are the head 2 of the load beam 18, respectively.
4 bonding pads 3 formed on the side opposite to 2
4 is connected.

On the surface (first surface) of the load beam 18 on which the head 22 is mounted, piezoelectric elements 36 and 38 are provided substantially parallel to each other in the longitudinal direction, and on the second surface of the load beam 18. Are provided with piezoelectric elements 40 and 42 facing the piezoelectric elements 36 and 38, respectively. The piezoelectric elements 40 and 42 are also substantially parallel to each other.

Bonding pad 3 of load beam 18
A plate 44 is attached to the second surface of the end portion on the fourth side to increase rigidity, and the plate 44 and the load beam 18 have a shaft member (see FIG. 1) for rotating the load beam 18. A hole 46 is formed for the shaft member 10). The hole 48 at the approximate center of the load beam 18 and the hole 50 on the head 22 side are used for positioning the load beam 18 when assembling the magnetic disk device.

The piezoelectric elements 36 and 38 are connected to the bonding pads 52 and 54 by signal patterns 51 and 53 formed on both sides of the signal patterns 32A, 32B, 32C and 32D, respectively.
And 42 are connected to the bonding pads 58 and 62 by signal patterns 56 and 60 formed on the second surface of the load beam 18, respectively.

FIG. 3 is a sectional view taken along the line AA in FIG.
An insulating layer 64 is formed on the first surface of the load beam 18, and the piezoelectric elements 36 and 38, the signal patterns 32A, 32B, 32C and 32D for the head 22, and the signal patterns for the piezoelectric elements 36 and 38 are formed. 51 and 53 are provided on the insulating layer 64.

An insulating layer 6 is formed on the second surface of the load beam 18.
6 are formed, and the piezoelectric elements 40 and 42 and the signal patterns 56 and 60 for the piezoelectric elements 40 and 42 are provided on the insulating layer 66. Note that the insulating layers 64 and 66 are not shown in FIG.

The respective piezoelectric elements 36, 38, 40 and 42 are
The electrode layer 68, the buffer layer 70, the piezoelectric thin film 72, and the electrode layer 74 are laminated in this order from the insulating layer 64 side.

The electrode layers 68 and 74 are made of a metal such as Au, and the buffer layer 70 is made of SiO ₂ . As the material of the piezoelectric thin film 72, ZnO oriented by sputtering or the like can be used. As the piezoelectric thin film 72, a thin film having a perovskite structure such as PZT, PLZT, or barium titanate can be used in addition to the ZnO thin film.

In FIG. 3, reference numeral 76 indicates the piezoelectric element 3.
6 shows bonding wires for connecting the electrode layers 74 of 6, 38, 40 and 42 to the signal patterns 51, 53, 56 and 60, respectively. Piezoelectric elements 36, 38, 4
The electrode layers 68 of 0 and 42 are grounded by a ground pattern (not shown).

In each piezoelectric element, the piezoelectric thin film 72 has a thickness of, for example, about 1 to 3 μm, and the buffer layer 70 has a thickness of, for example, about 0.2 μm. The buffer layer 70 is provided to prevent electrostatic breakdown of the piezoelectric thin film 72. A buffer layer may be further formed between the electrode layer 68 and the insulating layers 64 and 66.

In FIG. 3, the thickness of each piezoelectric element is shown to be larger than the length of the bent portion 18A, but this is for the purpose of describing the cross-sectional structure of each piezoelectric element in detail.

When a voltage is applied to the piezoelectric thin film 72, the piezoelectric thin film 72
The film 72 expands and contracts in the direction from the electrode layer 68 to the electrode layer 74.
Do (D₃₃Mode) On the other hand, the direction orthogonal to this, especially
It also expands and contracts in the longitudinal direction of the load beam 18 (d₃₁Mo
De). In the present embodiment, this d ₃₁Piezoelectric about modes
Tracking correction of the head 22 etc. by using expansion and contraction of thin film
Is going.

FIG. 4 is an operation explanatory diagram in this embodiment. In the tracking correction, when the head 22 is slightly displaced in the substantial radial direction of the magnetic disk (may be simply referred to as “radial direction”), as shown in FIG. Piezoelectric element 3 that expands and contracts in the same phase
A voltage signal is applied to each piezoelectric element so that 8 and 42 expand and contract in phase and piezoelectric elements 36 and 38 expand and contract in antiphase.

For example, when such a voltage signal causes the piezoelectric elements 36 and 40 to expand and the piezoelectric elements 38 and 42 to contract, the load beam 18 bends in the plane of the drawing, and the head 22 moves in the radial direction as indicated by the solid arrow 78. Is slightly displaced.

On the other hand, when a voltage signal is applied so that the piezoelectric elements 36 and 40 contract and the piezoelectric elements 38 and 42 expand, the head 22 is radially oriented in the opposite direction to that described above, as indicated by the dashed arrow 80. A slight displacement.

An example of the voltage signal waveform in this case is shown in FIG.
Shown in In FIG. 5, reference numerals 136, 138, 140 and 148 indicate waveforms of voltage signals applied to the piezoelectric elements 36, 38, 40 and 42, respectively.

During the period of time (t ₁ -t ₂ ), the head 22 is slightly displaced in the direction shown by the arrow 78 in FIG. A controlled voltage signal of is applied. In accordance with the principles described above, the voltage signal waveforms 136 and 13
8 have opposite phases to each other, and voltage signal waveforms 136 and 140
Are in phase and the voltage signal waveforms 138 and 142 are in phase.

Tracking correction is not performed during the period of time (t _{2 to} t ₃ ), and rough tracking is performed by, for example, an electromagnetic actuator during this period. During the period of time (t _{3 to} t ₄ ), the head 22 is slightly displaced in the direction indicated by the broken line arrow 80 in FIG. 4A, and the controlled voltage signal for tracking correction is generated during this period. It is given to each piezoelectric element.

In the present embodiment, the load beam 18
When one side receives a shearing stress in the extending direction, the other side receives a shearing stress in the contracting direction, so that the displacement amount of the head 22 per unit applied voltage can be increased, which is effective. Micro displacement is possible.

Further, since the reproducibility of the expansion / contraction amount per unit applied voltage of each piezoelectric element is good, it is possible to perform a highly accurate minute displacement of the head. The head 22 is in a direction perpendicular to the magnetic disk surface (sometimes referred to simply as "up and down direction").
4B, the piezoelectric elements 36 and 38 expand and contract in-phase, the piezoelectric elements 40 and 42 expand and contract in-phase, and the piezoelectric elements 36 and 40 reverse-phase as shown in FIG. 4B. A voltage signal is applied to each piezoelectric element so as to expand and contract with.

For example, when a voltage signal is applied in the direction in which the piezoelectric elements 36 and 38 expand and the piezoelectric elements 40 and 42 contract as shown in the drawing, the head 22 causes the head 22 to move vertically in the vertical direction as indicated by the solid arrow 82. Slightly displaced in the direction of approaching. When the head 22 is slightly displaced in the vertical direction in the direction away from the magnetic disk surface, a voltage signal opposite to the above is used.

By thus displacing the magnetic head 22 in the vertical direction as required, the load / load of the head can be improved.
It is possible to achieve the unload function and prevent accidents such as head crashes.

An example of the voltage signal waveform in this case is shown in FIG.
Shown in In FIG. 6, reference numerals 236, 238, 240 and 242 respectively denote the piezoelectric elements 36, 38, 40 and 4 when the head 22 is slightly displaced in the vertical direction.
2 shows the waveform of the voltage applied to No. 2. The voltage waveforms 236 and 238 are in phase, the voltage signal waveforms 236 and 240 are out of phase with each other, and the voltage signal waveforms 240 and 242 are in phase.

During the period of time (t _{5 to} t ₆ ), a voltage is applied to each piezoelectric element, and the head 22 is indicated by a solid arrow 82 in FIG. 4B according to the amplitude of the voltage waveform. A small amount of displacement in the direction can be obtained, whereby a desired distance between the head 22 and the magnetic disk surface can be obtained.

FIG. 7 is a sectional view of a head support mechanism showing another embodiment of the present invention. In this embodiment, each piezoelectric element 3
6, 38, 40 and 42 are characterized in that a resistor R is connected in series between the electrode layers 68 and 78, respectively.

Now, it is assumed that the load beam 18 is excited by the impact or the like applied to the load beam 18. Load beam 1
The elastic energy stored in 8 is converted into kinetic energy that tries to deform the load beam 18 in the opposite direction at the moment when the load beam 18 elastically deforms, but the resistor R is provided. As a result, the above-mentioned kinetic energy is reduced by the amount of Joule heat radiated outside the system in the resistor R. This makes the load beam 1
The vibration-damping action of No. 8 occurs.

It is desirable that the resistance value of the resistor R be large enough not to affect the application of voltage to each piezoelectric element. In the present embodiment, the resistor R is connected to all four piezoelectric elements, but the above-described damping effect can be obtained by connecting the resistor to at least one of the piezoelectric elements.

In the above embodiment, when the head 22 is displaced in the radial direction, the load beam 18 has a thickness of 20.
μm, the thickness of the piezoelectric thin film 74 is 2 μm, and the electrode layers 60 and 7
When the voltage applied between 4 is 50 V, the displacement of the head 22 can be 0.3 μm, for example.
Further, when the head 22 is displaced in the vertical direction under the same condition, displacement on the order of μm is possible.

Since the piezoelectric thin film 72 has a high resistivity, the bonding wire for applying a voltage to the piezoelectric thin film 72 and the cross-sectional area of the signal pattern can be small. Therefore, the surface area of the load beam 18 hardly increases due to the addition of the signal pattern for applying the voltage to the piezoelectric body.

[0043]

As described above, according to the present invention,
As a result, it is possible to provide a head support mechanism of a disk device capable of highly accurate and efficient minute displacement for tracking correction and the like.

[Brief description of drawings]

FIG. 1 is a plan view showing an example of a conventional head support mechanism of a magnetic disk device.

FIG. 2 is a perspective view of a head support mechanism showing an embodiment of the present invention.

FIG. 3 is a sectional view taken along line AA in FIG. 2;

FIG. 4 is an operation explanatory view of the head support mechanism of FIGS. 2 and 3.

FIG. 5 is a diagram showing an example of a voltage signal waveform.

FIG. 6 is a diagram showing another example of a voltage signal waveform.

FIG. 7 is a sectional view of a head support mechanism showing another embodiment of the present invention.

[Explanation of symbols]

 18 load beam 22 head 36, 38, 40, 42 piezoelectric element 72 piezoelectric thin film

Claims (4)

[Claims] 1. A head that reproduces at least data from and rotates a disk, and a plate-shaped elastic body having a first end and a second end, wherein the head is mounted on the first end. The second end is a rotatably supported load beam for moving the head substantially in the radial direction of the disk, and a second end is provided on one surface of the load beam substantially parallel to the longitudinal direction of the load beam. First and second piezoelectric thin films, and third and fourth piezoelectric thin films provided on the other surface of the load beam so as to be substantially parallel to each other in the longitudinal direction and to face the first and second piezoelectric thin films, respectively. And a first to a fourth electrode pair for applying a voltage to each of the first to the fourth piezoelectric thin films in the thickness direction thereof, and a head support mechanism of a disk device. 2. The first and third piezoelectric thin films and the second piezoelectric thin film
And the fourth piezoelectric thin film expands and contracts in the same phase, and the first and second piezoelectric thin films and the third and fourth piezoelectric thin films expand and contract in opposite phases, respectively. The device according to claim 1, further comprising means for applying a voltage signal to the electrode pair.
A head support mechanism for the disk device described. 3. The first and second piezoelectric thin films and the third piezoelectric thin film
And the fourth piezoelectric thin film expands and contracts in the same phase, and the first and third piezoelectric thin films and the second and fourth piezoelectric thin films expand and contract in opposite phases, respectively. The device according to claim 1, further comprising means for applying a voltage signal to the electrode pair.
A head support mechanism for the disk device described. 4. The head support mechanism for a disk device according to claim 1, further comprising a resistor connected in series to at least one electrode pair of the first to fourth electrode pairs.