JPH04119572A - Magnetic head positioning mechanism and magnetic circuit - Google Patents

Abstract

PURPOSE:To reduce a thermal offtrack amount and to prevent the read error of data by interposing an elastic magnetic substance between a yoke and a permanent magnet. CONSTITUTION:A permanent magnet 6 is respectively held through an elastic magnetic substance 7 to a yoke 5, and the yoke 5 is similarly held through the elastic magnetic substance 7 to spare base plates 3 and 4. This elastic magnetic substance 7 forms the magnetic circuit for compensating a magnetic gap between the permanent magnet 6 and the yoke 5. Assuming that a bimetal state is generated according to the difference between the linear expansion coefficients of the permanent magnet 6 and the yoke 5 by the temperature increase or environmental temperature change of the device to generate thermal striction or that the bimetal state is generated by the difference between the linear expansion coefficients of the yoke 5 and the spare base plates 3-4 so as to generate thermal striction, this thermal striction is absorbed by the elastic magnetic substance 7. Thus, there is no thermal offtrack amount and the read error of data is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic circuit in a magnetic disk device and a magnetic head positioning mechanism using the same.

[Conventional technology]

Generally, in a movable head type magnetic disk drive, as soon as there is a request to read specific information on the magnetic disk, the movable head must be rapidly positioned in the radial direction of the magnetic disk so as to minimize the read time. , in FIG. 2, the magnetic head 10 is connected to the magnetic disk 1.
The support arm 9 moves radially above the magnetic disk 11 by the swinging movement of the support arm 9, thereby positioning the magnetic head 10 at a predetermined position on the magnetic disk 11. Here, the position of the magnetic head 10 is controlled by detecting the position of the magnetic head 10 by a head assembly (hereinafter referred to as a servo head) having a first detection function, and then by a voice coil motor control circuit. When the coil 8 is energized, a force is generated between the magnetic circuit and the coil 8 due to the magnetic field of the permanent magnet 6 provided in the magnetic circuit, and the support arm 9, which is integrally assembled with the coil 8 and is swingable, is moved around the coil. This is performed by a servo circuit system forming a closed loop in which the head assembly mounted on the support arm 9 is oscillated by the force generated at the magnetic head 8, and the movement of the magnetic head 10 is similarly detected.

By the way, in order to improve the recording density of a magnetic disk device and increase the storage capacity of the device, it is necessary to improve the positioning accuracy of the magnetic head with respect to the magnetic disk. The magnetic head positioning device in current magnetic disk drives has a servo head dedicated to positioning, and this servo head reads positioning information pre-recorded on the magnetic disk surface and performs positioning based on the read information. There is. Therefore, the relative position error between the servo head and the head assembly (hereinafter referred to as data head) that writes and reads other information, and the relative displacement amount between the servo disk on which positioning information is written and the other data head. becomes the deviation amount from the track amount that should be followed, that is, the off-track amount. The smaller the off-track amount, the higher the positioning accuracy. However, in reality, an amount of off-track that is more than permissible may occur due to various factors. Among this amount of off-track, off-track caused by a rise in device temperature or a change in environmental temperature is called thermal off-track, and is mainly caused by differences in linear expansion coefficients between the various mechanical parts that make up the magnetic disk device. considered to be a contributing factor.

[Problem to be solved by the invention]

In the conventional magnetic disk device described above, the materials of the permanent magnet 6 and yoke 5 that constitute the magnetic circuit in the space surrounded by the upper substrate l and the lower substrate 2, as well as the upper auxiliary substrate 3 and the lower auxiliary substrate 4 are different. Therefore, the linear expansion coefficient is important. Each component is fastened with screws. Therefore, when the temperature of the device or the environment changes, the yoke 5 and the permanent magnet 6, the yoke 5 and the upper auxiliary board 3 and the lower auxiliary board 4 become bimetallic and thermal distortion occurs, causing distortion of the magnetic head positioning mechanism. If a relative positional error occurs between the servo head and the data head, or if the distortion of the magnetic head positioning mechanism extends to the upper substrate 1 or the lower substrate 2, a relative displacement occurs between the servo disk and the data head. There is a so-called thermal off-track amount, which has the drawback of causing data reading errors.

An object of the present invention is to provide a magnetic circuit and a magnetic head positioning mechanism that eliminate the amount of thermal off-track and prevent data reading errors.

[Means to solve the problem]

In order to achieve the above object, a magnetic head positioning mechanism according to the present invention includes a housing, a support arm, a coil, and a magnetic coil, the housing being rotatably supported. The support arm is attached to the housing and swings to move the magnetic head in the radial direction of the magnetic disk, and the coil is attached to the housing and swings in synchronization with the support arm. The magnetic circuit generates magnetic force by applying electricity from the outside, and the magnetic circuit applies rotational force to the housing through magnetic interaction with the magnetic force generated in the coil, and has a set of a yoke and a permanent magnet. The permanent magnet is supported by a yoke via an elastic magnetic material, the yoke is supported by a magnetic circuit support via an elastic magnetic material, and the elastic magnetic material is a yoke. This absorbs the thermal strain that occurs between the permanent magnet, yoke, and magnetic circuit support.

Further, in the magnetic circuit according to the present invention, the magnetic circuit is used in an environment where temperature changes occur, and the magnetic circuit is composed of a combination of a yoke and a permanent magnet. An elastic magnetic material is interposed between the permanent magnets and the yoke, and the elastic magnetic material absorbs thermal strain generated between the permanent magnet and the yoke.

[Effect]

The elastic magnetic body 7 forms a magnetic circuit that compensates for the magnetic gap between the permanent magnet 6 and the yoke 5.

This elastic magnetic body 7 is made of magnetic rubber or the like. Due to the difference in linear expansion coefficient between the permanent magnet 6 and the yoke 5, thermal strain generated between the two is absorbed by the elastic magnetic body 7.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a longitudinal sectional view showing an example of the present invention.

In the figure, an upper substrate 1 and a lower substrate 2 are combined in a box shape, and within this internal space, magnetic disks 11 are stacked in multiple stages and rotatably installed.

Furthermore, the following components are included in the internal space formed by the upper substrate 1 and the lower substrate 2.

That is, the housing 12 is rotatably supported between the upper auxiliary board 3 and the lower auxiliary board 4 via bearings 13a and 13b. A support arm 9 is mounted on the housing 12 so as to face the magnetic disk 11.
A magnetic helad 10 for writing and reading data to and from the magnetic disk 11 is attached to the tip of each support arm 9, respectively. Furthermore, the coil 8 is integrally attached to the housing 12.

Furthermore, yokes 5 are attached to opposing end surfaces of the upper auxiliary board 3 and the lower auxiliary board 4 with an elastic magnetic material 7 such as magnetic rubber interposed therebetween, and a pair of yokes 5, Permanent magnets 6 are attached to opposite end surfaces of the magnets 5 through an elastic magnetic material 7 such as magnetic rubber.
A magnetic gap G is formed between the pair of permanent magnets 6, 6, and a coil 8 is disposed within the magnetic gear G. Here, a magnetic circuit is constituted by the yoke 5, the permanent magnet 6, etc. Here, when the coil 8 is energized by a voice coil motor control circuit (not shown), a force is generated between the magnetic force generated in the coil 8 and the magnetic circuit, and a rotational force acts on the housing 12 to which the coil 8 is attached. The support arm 9 swings, the magnetic head 10 mounted on the support arm 9 swings in the radial direction of the magnetic disk 11, and data is written and read.

In the embodiment, the permanent magnets 6 are each held by the yoke 5 via an elastic magnetic body 7. The yoke 5 is also held on the upper auxiliary board 3 and the lower auxiliary board 4 through the elastic magnetic material 7. The elastic magnetic material 7 compensates for the magnetic gap between the permanent magnet 6 and the yoke 5. It forms a magnetic circuit and is mainly made of magnetic rubber or the like. By the way, due to an increase in the temperature of the device or a change in the environmental temperature, the permanent magnet 6 and the yoke 5 become bimetallic due to the difference in linear expansion coefficient, resulting in thermal distortion. Also, due to the difference in linear expansion coefficient between the yoke 5, the upper auxiliary substrate 3, and the lower auxiliary substrate 4,
It becomes a bimetal and thermal distortion occurs.

However, according to the present invention, since the elastic magnetic material 7 is interposed between the yoke 5 and the permanent magnet 6, and between the yoke 5 and the upper auxiliary board 3 and the lower auxiliary board 4, this thermal strain is caused by the elastic magnetic material 7. absorbed and does not cause distortion to the magnetic head positioning mechanism.

〔Effect of the invention〕

As explained above, according to the magnetic circuit according to the present invention, since the elastic magnetic material is interposed between the yoke and the permanent magnet, the thermal strain generated between the yoke and the permanent magnet is absorbed by the elastic magnetic material. can do.

Furthermore, according to the magnetic head positioning mechanism according to the present invention, it is possible not only to absorb thermal strain occurring in the magnetic circuit, but also to create elastic magnetic properties between different materials having different coefficients of linear expansion for absorbing thermal strain. Since the magnetic head positioning mechanism is provided with a body, even if the temperature of the device or the environment changes, the magnetic head positioning mechanism will not be distorted, and the upper and lower substrates on which this magnetic head positioning mechanism is mounted will not be distorted. The amount of thermal off-track can be reduced to prevent
This has the effect of preventing data reading errors.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention, and FIG. 2 is a longitudinal sectional view showing a conventional magnetic disk device. 1... Upper board 2... Lower board 3...
Upper auxiliary board 4...Lower auxiliary board 5...Yoke 7...Elastic magnetic body 9...Support arm 11...Magnetic disks 13a, 13b---Bearing 6...Permanent magnet 8...・Coil 10...Magnetic head 12...Housing agent Masu-buried field 1 Figure 2

Claims (2)

[Claims] (1) A magnetic head positioning mechanism including a housing, a support arm, a coil, and a magnetic coil, wherein the housing is rotatably supported, and the support arm is attached to the housing and swings. The magnetic head is moved in the radial direction of the magnetic disk, and the coil is attached to the housing and swings in synchronization with the support arm, and generates magnetic force by applying electricity from the outside. The magnetic circuit applies rotational force to the housing through magnetic interaction with the magnetic force generated in the coil, and has a set of a yoke and a permanent magnet.The permanent magnet is supported by the yoke via an elastic magnetic material. The yoke is supported by the magnetic circuit support via an elastic magnetic material, and the elastic magnetic material absorbs heat generated between the yoke and the permanent magnet, and between the yoke and the magnetic circuit support. A magnetic head positioning mechanism characterized by absorbing distortion. (2) A magnetic circuit used in an environment where temperature changes occur, and the magnetic circuit consists of a combination of a yoke and a permanent magnet, with an elastic magnetic material between the permanent magnet and the yoke. A magnetic circuit characterized in that the elastic magnetic material absorbs thermal strain generated between the permanent magnet and the yoke.