JPS6356640B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a magnetic disk drive device.

(Prior art) In the driving device for a floppy disk, for example, a 3.5-inch floppy disk, the centering hub of the floppy disk rotatably housed in a disk case is made of a magnetic metal plate such as an iron plate. The hub is attracted by a chuck magnet driven by a disk drive motor to couple the two.

(Problem to be solved by the invention) In recent years, this type of disk drive device has rapidly become lighter, thinner, and smaller, and as a result, there is no longer enough space between each component of the device. ing. Furthermore, the seek speed and resolution of the magnetic head, which is moved linearly in the radial direction of the floppy disk by a linear actuator, are increasing, but in order to increase the seek speed, the thrust of the linear actuator must be It is necessary to increase the magnetic flux density, but for this purpose, it is necessary to use a permanent magnet with a high magnetic flux density for the linear actuator. However, as the magnetic flux density increases, the thrust of the linear actuator increases, but at the same time, leakage magnetic flux also increases. As a result, mutual leakage magnetic flux between the permanent magnet and the tracking magnet of the linear actuator has an adverse magnetic effect on the magnetic head and magnetic disk.

(Means for solving the problem) In order to reduce the influence on the magnetic head due to magnetic leakage between the permanent magnet of the linear actuator that drives the magnetic head and the tracking magnet of the floppy disk, The magnet is magnetized in the thickness direction, and the magnetic polarity on the upper end surface side of this chucking magnet and the magnetic polarity on the upper end surface side of the permanent magnet of the linear actuator and on the chucking magnet side are determined. are of different polarity.

(Embodiment) In FIGS. 1 and 2, the chassis 21 of the floppy disk device includes a disk case 22.
A head carriage 26, which is a movable body that holds a magnetic head 25 for writing or reading information signals on the disk 23, is linearly moved. A linear actuator 27 is provided. The disk case 22 is positioned and placed on a plurality of support positioning pins 18 fixedly planted on the board.

The centering hub 23a of the disk 23 in the case 22 is located at approximately C.
The centering hub 23a is attracted to the chucking head 13 by the chucking magnet 50, and the engaging portion 32 provided on the centering hub 23a engages with the rotation stopper 31 provided on the chucking head 13. However, when the drive motor is rotationally driven, the disk 23 is urged to rotate.

The head carriage 26 has one guide bar 33
2 points, and 1 point due to another guide bar 34.
These two guide bars 33, 3
4 in the radial direction of the disk 23. two guide bars 3
3 and 34 are in the shape of round rods, and both ends thereof are fixed to the chassis 21 by pressing plates 35.

The linear actuator 27 includes a box-shaped yoke 36, flat plate-shaped permanent magnets 37 and 38 fixed vertically to the inner surface of the yoke 36, and a drive unit arranged in the gap between these permanent magnets 37 and 38. coil 3
9. Each of the permanent magnets 37 and 38 is magnetized in the thickness direction, with N and S poles formed in the thickness direction, but the magnetic poles are opposite to each other across the line that bisects each permanent magnet in the longitudinal direction. so that, and
The upper and lower magnets are arranged so that their different polarities face each other. The permanent magnets 37 and 38 serve as magnetic flux generation sources and are vertically opposed to each other with a predetermined gap therebetween, and together with the yoke 36 constitute a magnetic circuit.

The direction of magnetization in the thickness direction of the tracking magnet 50 and the permanent magnets 37 and 38 provided in the tracking head 13 are opposite to each other. That is, in FIG. 2, the upper magnetic poles of the permanent magnets 37 and 38 near the magnetic heads are S poles, and therefore, the upper part of the tracking magnet 50 is magnetized with N poles.

The drive coil 39 is placed on the tip of an arm-shaped mounting member 40, and the mounting member 40 passing through the window hole 30 of the yoke 36 is connected to the head carriage 26, so that the head carriage 26 is mounted together with the drive coil 39. It is designed to move in a straight line.

A position information recording medium 41 is fixed to the side of the head carriage 26, and a position sensor 42 is provided close to and facing the medium 41. In the position information recording medium 41, position information is recorded magnetically, for example, and this information is detected by a magnetoresistive element or the like. The position of the magnetic head 25 is controlled by a signal obtained by a position detecting section 43 consisting of a medium 41 and a position sensor 42, so that the magnetic head 25 matches each track of the disk 23 and stops.

The linear actuator 27 has a drive coil 3.
A speed detecting section 44 for detecting the moving speed of 9 is provided. The speed detection unit 44 includes a support arm 45 whose one end is connected to the head carriage 26, a magnet 46 attached to the chassis 21, a yoke 47 made of a magnetic metal plate, and a gap between the yoke 47 and the magnet 46. It has a flat detection coil 48. By energizing the drive coil 39 of the linear actuator 27, a thrust force is generated in a direction corresponding to the direction of the current, and the magnetic head 25 moves in the radial direction of the disk 23 together with the head carriage 26. As the drive coil 39 moves, the detection coil 48 also moves to the yoke 47.
Since the drive coil 39 moves while cutting the magnetic flux passing through the gap between the drive coil 39 and the drive coil 39, a voltage signal proportional to the moving speed of the drive coil 39 is detected from the detection coil 48. This detection signal is inputted to a control and drive circuit (not shown) together with the position signal obtained by the position detection section 43, and this control and drive circuit controls the linear actuator 27 based on the above-mentioned signals.
is moved at a predetermined speed to a predetermined position, and is positioned and stopped at the predetermined position.

In FIGS. 1 and 2, the drive motor M for rotating the disk 23 is connected to the rotor yoke 1.
2a, rotor magnet 12b, drive coil 16
and a spindle 10, and the spindle 10 is rotatably supported by a bearing 11 fixed to a chassis 21.
The chassis 21 is made of a steel plate or an aluminum plate.

The bearing 11 is composed of a holder 11a, a bearing portion 11b fitted and fixed inside the holder 11a, and a thrust bearing 11c that supports the thrust direction of the spindle 10.The holder 11a is fitted into a through hole 21a formed in the chassis 21. It is fixed.

A rotor 12 is fixed to the tip side of the spindle 10 via a tracking head 13.
The rotor 12 is a rotor yoke 12 formed in a substantially dish shape.
a and an annular rotor magnet 12b fixed to its inner surface. The chuck head 13 is formed into a substantially disk shape, and a rotor yoke 12a is fixed to the lower surface of the chuck head 13, and is fixed to the tip of the spindle 10. Also,
A rotation stopper 31 is provided on the chucking head 13 via an elastic member so as to be movable up and down and swingable in the radial direction.

On the other hand, a stator portion 14 is attached to the chassis 21 with respect to the rotor magnet 12b. The stator section 14 has a plurality of drive coils 16 placed concentrically on a thin printed circuit board 15, and has a fitting hole 15a in the center, and is used for driving to control the current to the drive coils 16. It has elements that make up speed control and drive control circuits, including ICs. This stator section 14 includes a printed circuit board 15
Bearing 1 with fitting hole 15a fixed to chassis 21
The holder 11a is fitted onto the outer periphery of the holder 11a, placed on the chassis 21, and fixed by the mounting screws 17.
As a result, the drive coil 16 is accurately positioned at a predetermined position and faces the rotor magnet 12b.

The printed circuit board 15 preferably has an insulating layer of resin, enamel, or the like applied to the surface of a thin plate made of a magnetic material such as an iron plate, and a copper foil circuit pattern formed on the insulating layer, similar to well-known printed circuit boards. Good. By using a printed circuit board using such an iron plate core, a magnetic circuit is formed on the printed circuit board itself, improving the efficiency of the motor. However, as long as the printed circuit board 15 itself is thin, it may be a well-known printed circuit board, and in any case, since it is attached to the chassis 21, even a thin printed circuit board will not affect the function of the motor. , from the viewpoint of reducing the thickness,
It is desirable to make it as thin as possible. Reference numeral 19 indicates a magnet of the rotational speed detector.

(Effect of the invention) Permanent magnets 37, 38 of linear actuator
When the direction of magnetization in the thickness direction of the charging magnet 50 is the same as that of the magnet 50, as shown in FIG. The direction of F2 becomes the same, and the magnetic head 25 is magnetized to one polarity (the S pole in the case of B and the N pole in the case of C), as shown in Figure 4 B and C. However, when the magnetization directions of the permanent magnets 37 and 38 and the tracking magnet 50 are reversed, as shown in FIG.
The direction of the magnetic flux F1 and the direction of the magnetic flux F2 passing through the magnetic head are opposite to each other, and the magnetic influence is canceled out, so that the function of the magnetic head is not hindered.

[Brief explanation of drawings]

FIG. 1 is a plan view of a magnetic disk drive device showing one embodiment of the present invention, FIG. 2 is a sectional view of the same, and FIG.
The figure is a diagram for explaining the magnetic influence of external magnetic flux on the magnetic head, and FIG. 4 is a diagram showing the magnetic flux state of the magnetic head. 13...Chacking head, 23...Magnetic disk, 23a...Centering hub, 25...
Magnetic head, 27... linear actuator,
37, 38...Permanent magnet, 39...Drive coil,
50...Characting magnet.

Claims (1)

[Claims] 1. A chucking head with a chucking magnet on the upper end surface that magnetically attracts the centering hub of the magnetic disk, a motor that rotationally urges the chucking head, and a chucking head that records information on the disk. A linear actuator that moves and urges the magnetic head in the radial direction of the disk by arranging a flat drive coil in a magnetic circuit that uses a magnetic head to be reproduced and a flat permanent magnet magnetized in the thickness direction as a magnetic flux generation source. and a magnetic head positioned between the tracking magnet and the linear actuator. A magnetic disk drive device characterized in that the magnetic polarities on the upper end surface side of the yuator and on the magnet side are different from each other.