JPH024072B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technology to which the invention pertains] The present invention relates to a swing type head positioning device using an electromagnetic drive method.

[Prior art]

2. Description of the Related Art It is known that a device for positioning a magnetic head relative to a recording track in a magnetic disk device or the like is constructed using a so-called voice coil type linear motor of an electromagnetic drive type. For example, the present applicant has already proposed a swing type head positioning device (Japanese Patent Laid-Open No. 67975/1983).

However, although various improvements have been made to this device, due to its structure, the end faces of the permanent magnets are open, and leakage of magnetic flux cannot be ignored. Furthermore, leakage magnetic flux has a negative effect on magnetic recording and reproduction, so there is a limit to how close a magnetic disk, a so-called magnetic recording medium, can be to the apparatus. Therefore, it is necessary to lengthen the head arm of the head positioning device, which poses a problem in reducing the size of the entire positioning device.

[Purpose of the invention]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a head positioning device which can solve the above-mentioned drawbacks, reduce the size of the device, and increase the driving force.

[Structure of the invention]

The present invention provides an oscillating head positioning device in which a head arm equipped with a magnetic head is fixed to a rotating shaft, in which a plurality of substantially rectangular coils are fixedly arranged on a plate surface attached to the rotating shaft, and the head arm is fixed to a rotating shaft. A plurality of magnets are fixedly arranged on each side of the coil extending in the radial direction of the shaft so as to apply a magnetic flux perpendicular to the plate surface, and each magnet generates a magnetic flux in the coil according to a current supplied to the coil. A part of the rotating shaft including the plate is placed in a container that is polarized so that electromagnetic force acts in the same rotating direction, and is made of a cup-shaped magnetic yoke and a magnetic yoke serving as a lid of the cup. and the plurality of permanent magnets are housed in a state in which the rotation shaft is rotatable.

〔Example〕

Examples of the present invention will be described below.

FIG. 1 shows a first embodiment of the invention in longitudinal section. In the figure, 1 is a rotating shaft made of non-magnetic material.
One or more head arms 2 are attached to the upper end. A magnetic head 3 is mounted at the tip of the head arm 2. Reference numeral 4 denotes a ring-shaped permanent magnet, which has four sets of different magnetic poles arranged alternately at intervals in the circumferential direction, as shown in FIG. 2. Reference numeral 5 denotes a coil, and as shown in FIG. 3, flat coils 5a to 5d having half the number of magnetic poles of the permanent magnet 4 are fixed to a disc 6 attached to the rotating shaft 1.
Reference numeral 7 denotes a cylindrical cup-shaped magnetic yoke, which supports the rotating shaft 1 via a bearing 8 on its inner bottom wall. Reference numeral 9 denotes a lid-shaped magnetic yoke that forms a yoke together with the cup-shaped yoke 7, and has a permanent magnet 4 fixed to its lower surface. The permanent magnet 4 and the coils 5a to 5d are arranged such that the respective magnetic poles face each other with a gap interposed between the coil sides extending in the radial direction. and,
The magnetic flux shown by the arrow in Figure 2 is made to pass through the coil sides perpendicular to the plate surface, and the electromagnetic forces F ₁ and F ₂ acting on the opposite sides of one coil are made to act in the same direction of rotation. There is. The rotation shaft 1 is also supported by a bearing 10 on the yoke 9.

In such a configuration, when a current is passed through each coil, an electromagnetic force based on Fleming's left hand rule is generated, and the rotating shaft 1 rotates in accordance with the current value. Since multiple sets of magnets and coils are arranged in the circumferential direction, the above proposal (Japanese Patent Application Laid-open No. 55-67975)
It is possible to increase the driving force compared to the device based on this method. In other words, if the same driving force is used, the structure can be made even smaller. Also,
As shown in FIG. 1, the magnet 4 and coil 5 are housed so as to be wrapped around the yokes 7 and 9.
Magnetic leakage from the magnetic circuit can be significantly reduced.
As a result, the head arm can be shortened, the head positioning device can be made smaller, and the entire magnetic disk device can also be made smaller.

FIG. 4 shows another embodiment of the invention. This embodiment is basically the same as that shown in Fig. 1, but coils 5a to 5d, 5a' to 5d' are fixedly installed on both the upper and lower surfaces of the disk 6, and the coils 5a to 5d are opposed to each other as shown in Fig. 2. Similar ring-shaped magnets 4a and 4b are fixed to the inner surfaces of the yokes 7 and 9. Reference numeral 11 denotes a magnetic fluid seal, which prevents dust generated by rotational wear of the rotating shaft 1 from being removed by the yoke 7,
9. This is to prevent leakage to the outside.

Note that the permanent magnet used in the present invention is not limited in material, size, or number of magnetic poles. For example, as shown in FIG. 5, a plurality of permanent magnets having magnetic pole axes in the thickness direction may be fixed onto a disk. Further, it goes without saying that the coil may be one built into a coil frame or a printed coil.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to provide a head positioning device that has a large driving force and can be downsized.

[Brief explanation of drawings]

FIG. 1 shows a first embodiment of the present invention in longitudinal section, FIGS. 2 and 3 are perspective views and plan views of the permanent magnet and coil, respectively, and FIG. FIG. 5 is a longitudinal sectional view of the embodiment, and FIG. 5 is a perspective view of another example of the permanent magnet. In the figure, 1 is a rotating shaft, 2 is a head arm, 3 is a magnetic head, 4 is a permanent magnet, 5 is a coil, and 7 and 9 are yokes.

Claims (1)

[Claims] 1. In an oscillating head positioning device consisting of a head arm equipped with a magnetic head fixed to a rotating shaft, a plurality of substantially rectangular coils are fixedly arranged on a plate surface attached to the rotating shaft, and the diameter of the rotating shaft is fixed. A plurality of magnets are fixedly arranged on each side of the coil extending in the direction so as to apply a magnetic flux perpendicular to the plate surface, and each magnet has an electromagnetic force generated in the coil according to the current supplied to the coil. A part of the rotating shaft including the plate and the plurality of rotating shafts are placed in a container that is polarized so as to act in the same rotational direction and that includes a cup-shaped magnetic yoke and a magnetic yoke serving as a lid of the cup. A head positioning device comprising a permanent magnet housed in such a manner that the rotation shaft can rotate.