JPH0197156A - Magnetic head positioner - Google Patents

Abstract

PURPOSE:To materialize non-contact guide of no dust generation, to make a driving mechanism compact and to improve reliability, by magnetically levitating a positioner moving element using minus effect generated in a superconductor. CONSTITUTION:Before the operation is started, a movable plate 2 is kept in contact with a part of a guide rail 1 according to the gravitational state. Under this condition, where the cooling gas is supplied from an air inlet 3, the whole system is so cooled that when it comes down to below critical temperature of a superconductive material, the flux from a permanent magnet 11 which has so far passed through the superconductive part is driven out to the outside of the superconductor. The movable plate 2 is repulsed due to what is called minus effect from the U-shaped permanent magnet 11 and gets non-contact.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical field to which the invention pertains The present invention relates to a magnetic head positioner used in a magnetic disk drive.

(2) Conventional technology and its problems Conventionally, in magnetic disk drives, information is recorded and reproduced by moving a magnetic head to any of a number of concentric information tracks arranged on a rotating medium. , the magnetic head was moving in the radial direction. Usually, a magnetic head is mounted on a carriage that has a linear guide mechanism that can move the medium in the radial direction, and is moved using the driving force of a voice coil motor.

As shown in Figure 1, the linear guide mechanism consists of a guide rail and a miniature bearing, and the bearings supported by the carriage move on the guide rail to reduce friction loss when the carriage moves. Also,
Efforts were made to reduce wear by constructing the surface that caused rolling friction with a high-hardness material and by finishing the surface smoothly. However, no matter how much effort is taken to reduce wear, in reality, dust is generated due to wear of the guide rail and veri-ring parts, and if this dust gets mixed in between the head media, it can damage the head and the media. In order to capture the dust, the air inside the housing was devised so that it passed through a filter when it was circulated. However, as is well known, the capture of dust by a filter is a stochastic event, and although there is a small percentage of dust that cannot be captured, this dust gets into the narrow gap between the head and the medium and causes problems such as head crashes, etc. This caused damage to the long-term reliability of the device.

Magnetic bearings that use the attraction of electromagnets and air bearings that use the pressure of high-pressure air are known as non-contact guidance mechanisms, but the former detects changes in position and stabilizes by controlling the electromagnetic attraction force. This method has not been put to practical use because it requires a complicated control circuit, the magnetic field leakage is large when generating the attractive force, and the information recorded on the magnetic recording medium is easily erased. Furthermore, since the latter uses a compressor with sliding parts to generate high-pressure air, there is a risk that dust may be mixed into the high-pressure air. In addition, they both have the disadvantage of requiring a large amount of electric power to maintain guidance accuracy.

In addition, voice coil motors have traditionally been used to generate driving force, but when trying to increase the density of the current flowing through the conductor in order to miniaturize the coil, heat generation increases and the coil adhesive and other In order to reduce page pulling performance, it is necessary to set the current density to about 10'A/2 cylinders, and as a result, there is a limit to the miniaturization of the voice coil motor.

Furthermore, since the coil generates heat, the temperature within the device increases, causing track misalignment, which is an impediment to improving track density.

Furthermore, the positioner is basically made up of a guide mechanism and a driving force generating mechanism, and processes such as adhesion and assembly are required to connect these.

(3) Purpose of the Invention The present invention utilizes a negative effect to magnetically levitate the movable part of the positioner in order to achieve low power and non-contact operation, and the drive coil is made of superconducting material to reduce electrical resistance to zero. The present invention provides a magnetic head body that does not generate heat in principle.

(4) Structure of the invention The present invention will be explained in detail below.

(4-1) Difference between the characteristics of the invention and the prior art The conventional guide mechanism used bearings, but in the present invention, a superconducting material is used between a pair of multi-pole magnetized permanent magnets. By arranging the formed plates and setting the entire system below the critical temperature, magnetic levitation is achieved using the Meissner effect that occurs in superconductors, essentially eliminating the need for positional control or electric power for levitation. Moreover, high support rigidity can be obtained.

(4-2) Embodiment FIG. 1 shows an example of a guide mechanism according to the present invention, in which 1 is a guide rail composed of permanent magnets, 2 is a movable plate, 3 is an air supply hole,
4 is an aperture, 10 is a voice coil section, 11 is a driving magnet,
21 shows the head arm attachment part.

A magnetic helad arm (not shown) is attached to the section 21 using the attachment hole 21a. Although the magnetic recording medium facing the magnetic head and its drive mechanism are not shown, they are similar to the conventional structure. At least the surface of the movable plate 2 facing the U-shaped permanent magnet is made of a superconducting material.

Since the movable plate 2 is in a normal conductive state before the start of operation, the movable plate 2 is in contact with a part of the guide rail 1 according to the gravitational state. When cooling gas is supplied from the air supply hole 3 in this state, the entire system is cooled, and when the temperature falls below the critical temperature of the superconducting material, the magnetic flux from the permanent magnet 1 that has passed through the superconducting portion is expelled to the outside of the superconductor. Due to the so-called Meisner effect, the movable plate 2 is repelled from the U-shaped permanent magnet and becomes non-contact.

The rigidity of the magnetic bearing increases as the gradient in which the relationship between the magnetic flux density φ to be rejected due to the Meissner effect decreases due to the gap d between the movable plate 2 and the guide rail 1, that is, −θφ/θd increases. Since the permanent magnet 1 according to the present invention is magnetized with opposite polarity by repeating the pitch L as shown in FIG. 2, the magnetic flux rapidly attenuates as it rises from the surface of the multipolar magnetized permanent magnet. Magnetic flux density φ at the surface of a permanent magnet. For φ=φ. It is expressed by the relationship exp (-πd/L), and higher rigidity can be obtained than in the case without multi-pole magnetization.

Although it is difficult to form the above-mentioned multi-pole magnetized region evenly and over a long section, the guide distance required in a positioner for a magnetic disk is at most about 2 to 5 cm.
There is no problem in laminating and forming magnetized permanent magnet plates of about 0.1 mm.

Since both ends are used as guide mechanisms, the movable plate 2
It is extremely easy to incorporate the superconducting voice coil 10 for generating a driving force in the direction of arrow A+ into the central portion of the vehicle. The operation of the voice coil is exactly the same as that of a normal flat coil type voice coil motor. Naturally, the electrical resistance is zero at a temperature where the Meissner effect can be expressed, and the coil can be constructed by forming a superconducting material into a wire. In addition, since there is no heat generation, it is possible to increase the current density of the coil to the upper limit (Jc) that can sustain the superconducting phenomenon. For example, if a material with Jc = 106 A/mm" is used, the volume of the coil can be reduced to 1/1 of the current density. 100, and it is also possible to use a spiral coil by photo-etching or the like.In other words, on the substrate 30 made of ceramic or the like shown in FIG. A superconducting material film 31 is formed as shown in Figures 3 and 3), and a mask is applied as shown in Figure 3C so that both ends are left and a coil is formed in the center, and then etched to form a superconducting material film 31 as shown in Figure 3D. Just make a spiral groove like this.

For example, in the case of a superconducting material based on B az Y Cu x O, such processing can be performed by phosphoric acid etching or ion etching using a mask 32. Conventionally, the coil is bonded to a support and then The manufacturing process of the positioner movable part is extremely simple compared to the manufacturing process of the positioner movable part, which is assembled into a guide mechanism composed of a bearing or the like. Furthermore, since making the coil thinner improves the efficiency of the magnetic circuit that generates the magnetic field applied to the coil, the voice coil motor magnet 11 can also be made smaller, and the entire magnetic head positioner can therefore be configured extremely compactly. It's self-evident. Furthermore, since there is no coil heat generation, off-track due to heat generation does not occur in principle, and there is an advantage that the track density can be increased.

In addition, in the present invention, since the cooling gas is supplied from the air supply hole arranged in the permanent magnet, the floating blade also works as a static pressure gas bearing, and although the force is weaker than that of the floating blade due to the Meisner effect, it can be used in the event of an abnormality. It has the characteristic that even if the superconducting state is broken, the movable plate can be kept non-contact.

(5) As described in detail, according to the present invention, it is possible to easily realize non-contact guidance that does not generate any dust due to wear of the guide rail and bearing parts, and also because there is no heat generated by the coil, the drive mechanism This makes it possible to have an extremely compact configuration, making it possible to realize a highly reliable magnetic disk device with high track density.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a structural example of a guide mechanism according to the present invention;
FIG. 2 is a sectional view taken along the plane X2 of FIG. 1 to show the magnetized state of the guide rail magnet according to the present invention, and FIG. 3 shows the process of forming the movable plate. DESCRIPTION OF SYMBOLS 1... Guide rail composed of a permanent magnet 2... Movable plate, 3... Air supply hole, 4... Diaphragm, 10... Voice coil section, 11... Drive magnet, 21...・Head arm mounting section, 21a...Mounting hole, 30.
...Substrate, 31...Superconducting film, 32...Mask. Patent applicant Nippon Telegraph and Telephone Corporation

Claims (1)

[Claims] It has a linear guide mechanism consisting of a movable plate whose at least both ends are made of superconducting material and a U-shaped permanent magnet that supports both ends of the movable plate, and the permanent magnet is multi-pole magnetized. magnetic head positioner.