JPS6043271A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To prevent the vibration of a rotating shaft, eliminate an error in the positioning of a magnetic head and reduce readout errors by providing an O ring eccentrically with the ball bearing hold part of the flange of a stopping motor, and supporting a ball bearing through the O ring. CONSTITUTION:An O ring groove 87b having a center B at distance delta from the center A of the bearing hold part 87a is provided in the bearing hold part 87a, and the bearing 88 is inserted by compressing the inside of the O ring 89 fitted in the O ring groove 87b. The external ring flank of the bearing 88 is pressed axially by a step ring 90 fitted in the bottom part of the bearing hold part 87a, so it is capable of a slight movement axially while deforming the O ring 89. The stepping motor 8, therefore, has the center B of the rotating shaft 81 supported by the O ring 89 at the position eccentric with the center A of the bearing hold part 87a by distance delta, so the tip of the rotating shaft never vibrates.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic disk device, and more particularly to a magnetic disk device that uses a stepping motor to drive a positioning device for writing or reading information.

In recent years, with the development of small star information processing devices such as Office Compico, Yuu and Word Glow, 1, there was a need for a small abrasive disk device suitable for use with these devices. , with a diameter of 2 as compatible with this.
Small 7z about 0cm or 13cm! FC magnetic disk*tis has been put into practical use using a magnetic disk.

These magnetic disk devices need to be small, easy to handle, and inexpensive.
A positioning device (usually called a carriage) that positions the magnetic head on a predetermined track on the magnetic disk. - Some have configurations that use stepping motors for driving.

A stepping motor used in a magnetic disk device with such a configuration has a magnet (a large number of magnetic poles on the outer circumference) in the center, and a large number of magnetic poles on the inner surface facing the magnet. A rotating shaft is fixed to the stator (with windings of One of the ball bearings has a bearing holding part near its center for fixing (by press fitting or gluing) the outer ring of this ball bearing. It is held by a flange (hereinafter referred to as front flange),
The other ball bearing is a bearing retainer that fits with a small gap between it and the outer ring of the ball bearing.
M 9S is held by a second flange (hereinafter referred to as rear flange) Vc provided at the center of the flange, and a spring is provided between the bottom of the bearing holding portion of this rear flange and the outer ring of the ball bearing. .

By applying the pressing force of this spring to the outer rings of the ball bearings, it is possible to remove the play between the outer rings and balls of the two ball bearings, and between the balls and the inner rings. Therefore, there is a slight gap between the bearing holding part of the rear flange and the ball bearing to ensure relative movement between them as described above. The pulley that connects the magnetic head (on which a pulley is attached) causes vibration (direction is indeterminate) in a plane perpendicular to the axial direction, and the component of this vibration in the positioning direction of the magnetic head changes when writing and reading information. If they are different, this may result in a positioning error during reading and cause a read error in the magnetic disk device. Furthermore, FIG. 1 (FIG. 1 is a plan view showing the external appearance of one embodiment of the present invention, but since the external appearance of a conventional magnetic disk device is also the same as FIG. 1, please refer to FIG. 1 for convenience of explanation. As shown in Figure 2), the positioning distance (the distance between the rotation center of the magnetic disk 2 and the magnetic head 3) is the distance a between the rotation center of the magnetic disk 2 and the center of the rotation axis of the stepper motor 8, The distance between the center of the rotating shaft of the stepping motor 8 and the fixed end point of the steel band 6 wrapped around the pulley 7 attached to the tip of the rotating shaft.

It is determined as the algebraic sum of the distance C between the fixed end point of the steel band 6 and the support point of the gimbal spring 4 that supports the magnetic head 3, and the length d of the gimbal spring 4 that supports the magnetic head 3. If there is a temperature difference between writing and reading, there is a difference in the materials that make up each dimension (distance or length), so there will be a difference in the change in dimension due to the difference in thermal expansion coefficient, and the dimension e ( =a+
b-c-d), an error of Δe (usually referred to as thermal off-track) may occur, which may also cause read errors.

Therefore, an object of the present invention is to provide an eccentric O-ring in the ball bearing holding portion of the 7th leg of the stepping Tanabata and to support the ball bearing through this O-ring. By eliminating the gap between the ball bearing and its holding part and preventing the rotation axis from wobbling, it is possible to eliminate positioning errors of the magnetic head, thereby reducing read errors, and further improving the KO ring. By selecting the mounting position of the stepping motor so that the direction of the runout of the rotating shaft caused by eccentricity matches the direction that compensates for the positioning error of the magnetic head due to thermal off-track, reading errors due to thermal off-track can be avoided. An object of the present invention is to provide a highly reliable magnetic disk device with a reduced number of disks.

The magnetic disk device of the present invention includes at least one magnetic disk attached to a main shaft rotated by a motor, and at least one magnetic head mounted on a predetermined track of the magnetic disk. A magnetic disk device comprising: a stepping motor that drives a positioning device for positioning the magnetic disk device; two ball bearings mounted on a shaft; and two flanges having bearing holding portions for holding the ball bearings; an O-ring groove having a center at a position offset by a predetermined value with respect to the center ratio of the bearing seat on the inner periphery of the bearing holding portion, and at least one O-ring groove fitted in the O-ring groove; 0 ring.

Further, in another embodiment of the present invention, in the magnetic disk device described above, the direction of the deflection of the rotating shaft of the stepping motor caused by the eccentric direction of the O-ring groove is determined by positioning based on the temperature difference of the magnetic head with respect to the magnetic disk. A stepping motor is installed and set in a direction that compensates for the difference.

The present invention will be described in detail below with reference to the drawings.

FIG. 1 is a plan view showing an embodiment of the present invention, with a part of the cover cut away to show the internal structure.

It rotates at a constant speed around the magnetic disk 2 and varnish binder 1. On the other hand, the magnetic head 3 is a gimbal spring (a stainless steel gimbal spring that mounts and supports the magnetic head on its tip, flies the magnetic head a certain distance above the magnetic disk surface when writing or reading information, and maintains the correct flying posture. It is mounted on the tip of a leaf spring (made of steel material and has a special external shape) 4, and moves forward or backward toward the center of rotation of the magnetic disk 2 to move it to a predetermined track (track 2a in the figure). It is configured to be positioned above and write and read information. The gimbal springs 4 are stacked and mounted on the carriage base 5 (normally, since a plurality of magnetic disks are used, a plurality of gimbal springs are used corresponding to their axis storage surfaces), and the gimbal springs 4 are stacked on the carriage base 5. The center portion of the steel band 60 is fixed to the pulley 7, and both ends of the steel band 60 are fixed. The pulley 7 is a stepping motor 8!7 attached to the frame 9.
) The stepping motor 8 is attached to the tip of the rotating shaft, so that the rotational motion of the stepping motor 8 is converted into linear motion by the pulley 7 and the steel band 6, and the positioning operation of the magnetic head 3 is performed. There is. In addition, steel band 6# carriage base 5. The parts that perform linear motion, such as the impulse spring 4, are collectively referred to as a positioning device (carriage) along with other components.

FIG. 2(a) is a partially cross-sectional and exploded plan view showing the details of the configuration of the stepping motor of FIG. 1.

As shown in the figure, the stepping motor 8 has a magnet 86 fixed to the inner part of the rotating shaft 81, and ball bearings 83 and 86 on both sides of the magnet 86, whose inner ring is glued to the rotating shaft 81. Fixed. A stator 84 having a coil 85 is arranged around the outer periphery of the magnet 86 .

Front flange 82 corresponding to ball bearing 83
However, a rear flange 87 is provided corresponding to the ball bearing 88, and the ball bearing 83 is inserted into a bearing holding portion 82a provided at the center of the front flange 82, and its outer ring is fixed with adhesive. On the other hand, the ball bearing 88 is attached to the bearing holding portion 8 provided in the center of the rear flange 87.
The inner diameter of the bearing holding portion 87a is set to be slightly larger than the outer diameter of the outer ring of the ball bearing 88.

Inside the bearing holding portion 87a, there is an O-ring groove 87 having a center B at a position eccentric from the center A by a distance δ.
The bearing 88 is inserted into the O-ring groove 87b by compressing the inside of the O-ring 89 which is left unfitted in the O-ring groove 87b. The bearing 88 is also axially pressed against the side surface of its outer ring by a spring 90 installed at the bottom of the bearing holding portion 87a.
By deforming the ring 89, slight movement in the axial direction from 7r is possible.

Therefore, the stepping motor 8 configured as described above is configured such that the center B of the rotating shaft 81 is located at a position offset by a distance δ from the center A of the bearing holding portion 87a, as shown in FIG. 2(b). Since it is supported by OS/G89,
Unlike conventional stepping motors, the gap between the bearing holding portion 87a and the ball bearing 88 prevents the tip of the rotating shaft from swinging, which reduces positioning errors of the magnetic head 3 (see Figure 1). can be removed to reduce read errors. Mounting the O-ring eccentrically means that pressure is always applied to the ball bearing in a fixed direction, so changes in temperature may cause a change in the dimensional difference between the inner diameter of the bearing holding part and the outer diameter of the ball bearing. It is also possible to maintain a roughly constant pressure, which has the effect of stably maintaining the position of the rotating shaft. Although the above-mentioned embodiment has a configuration including a rear flange KO ring, it is also possible to fix the rear flange side and provide an O-ring on the front flange. Furthermore, it is also possible to provide O-rings on both the rear flange and the front flange, and in this case, the eccentric directions of the two can be combined in any desired manner.

In FIG. 1, for example, if the coefficient of thermal expansion of the 1,000 frame 9 that governs the dimension a is small (the coefficient of thermal expansion J of the carriage base 5 and the magnetic disk 2 that governs the dimensions C, e, and 7y) (the coefficients of thermal expansion J of the carriage base 5 and the magnetic disk 2 that govern the dimension It is assumed that the amount of dimensional change due to temperature difference is the same), and if the information read IQ is high relative to the temperature at the time of information writing, the magnetic head 3 will shift in the inner circumferential direction of the magnetic disk 2 (thermal off). track).

At this time, if the stepping motor can be moved in the direction shown in FIG. 2(b), that is, the eccentric direction of the ball bearing 88 is in the direction of the center of the magnetic disk in FIG.
The ball bearing 8 expands by the amount that the inner diameter of the bearing holding portion 87a of the rear flange 87 expands due to the rise in temperature IW.
8 is made more eccentric by the O ring 9o, and therefore the pulley 7 is moved in the direction away from the magnetic disk 2, so that the position of the 4fi air head 3 can be correctly positioned on the track 2a by compensating for the thermal off-track. It is also possible to prevent read errors due to thermal off-track. Of course dimensions a, b,
If thermal off-track does not occur between C9d and C9, the above-mentioned eccentric direction may be set perpendicular to the drawing of m1, and the desired thermal Off-track compensation can be provided.

As explained in detail above, by using the magnetic disk drive of the present invention, read errors can be reduced by preventing misalignment of the magnetic head due to the gap between the ball bearing of the stepping motor and the bearing holding portion of the flange. This has the effect of providing a highly reliable magnetic disk drive.Furthermore, read errors due to thermal off-track can be reduced by appropriately selecting the mounting angle of the stepping motor to compensate for thermal off-track. This has the effect of providing a highly reliable magnetic disk drive device with reduced energy consumption.

[Brief explanation of drawings]

FIG. 1 is a plan view showing an embodiment of the magnetic disk device of the present invention. FIGS. 2(a) and Φ) are exploded plan views partially showing the stepping motor in FIG. FIG. In the figure, l... spindle, 2... magnetic disk, 3... magnetic head, 4... gimbal spring, 5...... Carriage base, 6...
...Steel band, 7...Pulley, 8
...Stepping motor, 9...Frame, 81...Rotating shaft, 82...Front flange, 83...Pole bearing, 8
4... Stator, 85... Coil, 8
6... Magnet, 87... Rear flange, 88... Pole bearing, 89...
...0 ring, 90...spring. Figure 1 (11) Second hearing

Claims (2)

[Claims] (1) A positioning device that includes at least one magnetic detask rotated by a motor and attached to a main shaft, and at least one magnetic head, and positions the magnetic head on a predetermined track of the magnetic disk. A magnetic disk drive comprising: a stepping motor that drives a rotating shaft having a plurality of two-pole magnets attached to its outer periphery; and two magnets attached to the rotating shaft outside the magnet. a ball bearing, and two flanges having a bearing holding portion for holding the ball bearing, at least one of the two flanges having an inner periphery of the bearing holding portion. The O-ring groove has an O-ring groove whose center is eccentric by a predetermined value with respect to the center of the bearing holding portion, and at least one O-ring is fitted in the O-ring groove. A magnetic disk device that uses this as a percentage. (2) A stepping motor is installed with the direction of deflection of the rotating shaft of the stepping motor caused by the eccentricity of the O-ring groove set in a direction that compensates for positioning errors due to temperature differences of the magnetic head with respect to the magnetic disk. The magnetic disk device according to item (1), wherein the magnetic disk device is @ridge.