JPH0369071A - Rotary actuator for recording and reproducing device - Google Patents

Abstract

PURPOSE:To prevent the position of a transducer to a recording medium attending on a seeking operation from being deviated by providing a pre-loading means on the side of a fixed shaft so as to apply pre-load in a diameter direction to a ball bearing to support the transducer. CONSTITUTION:An actuator arm 7 is supported through ball bearings 15 and 17 around a vertical fixed shaft 13, which is pivotally supported to a connected board 31, so as to be freely rotated. Then, the actuator arm 7 is turned by a driving motor 5. As the transducer, a magnetic head 1 is provided on the tip side of each actuator arm 7 through a suspension 3. The ball bearings 15 and 17 are provided on the upper and lower parts of the fixed shaft 13. In the almost center of the fixed shaft 13 between the ball bearings 15 and 17, a step part 49 is formed so that the diameter on the ball bearing 15 side can be made small. Then, between the step part 49 and an inner ring 42, a coil spring 15 is provided to apply the pre-load to the inner ring 43 in the upper axial direction of the fixed shaft 13. Thus, the position of the magnetic head 1 can be prevented from being deviated to a magnetic disk 9 attending to seeking operation.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a rotary actuator for a recording/reproducing device equipped with a transducer that is movably positioned with respect to a recording medium to record and reproduce information. Regarding.

<Prior Art> In a winchiesta type magnetic disk device, a magnetic head as a transducer is supported at the tip of an actuator arm and is moved and positioned to an arbitrary position on an information track on a magnetic disk as a recording medium to record information. However, in recent years there has been an increasing demand for compact and high-capacity devices that can seek on information tracks at high speed.
There is a need for an actuator suitable for devices that are small and capable of high-speed seeking.

An example of such a magnetic disk device is shown in FIGS. 6 and 7. In this device, a suspension 3 having a magnetic head 1 at its tip is supported by an actuator arm 7 rotated by a drive motor 5. The magnetic head 1 is moved and positioned at an arbitrary position on the surface of the magnetic disk 9 by the rotation of the magnetic head 7. The actuator arm 7 has a boss portion 11 on the base end side.
It is rotatably supported by two upper and lower ball bearings 15 and 17 interposed between and the fixed shaft 13.

The lower ball bearing 17 has an outer ring and an inner ring fixed to the actuator arm 7 and the fixed shaft 13, respectively. On the other hand, the inner ring 19 of the upper ball bearing 15 is fixed to the fixed shaft 13, but the outer ring 21
is rotatable relative to the boss portion 11 of the actuator. This outer ring 21 is connected to a compression coil spring 23.
A preload is applied upward in the axial direction via the outer ring retainer 25, thereby preventing play of the ball bearing 15 in the axial direction. Further, a coil spring 27 is provided between the outer ring 21 and the boss portion 11 to apply a preload to the outer ring 21 in the direction of the magnetic head 1, thereby preventing play of the ball bearing 15 in the radial direction. 29 is a drive motor 5.
This is a housing in which the actuator arm 7, magnetic disk 9, etc. are housed.

(Problems to be Solved by the Invention) In the rotary actuator of the recording/reproducing device as described above, the coil spring 27 that applies preload in the radial direction of the ball bearing 15 is provided on the actuator side, so that the magnetic head 1 When moving in the radial direction on the magnetic disk 9 for seeking, the coil spring 27 rotates with the rotation of the actuator arm 7, and its preload direction changes. If the radial preload direction on the magnetic disk 15 is not constant and changes with the seek position, the preload direction may change due to temperature changes, especially when the magnetic head 1 is sought near the outer or inner circumferential side of the magnetic disk 9. ball bearing 1
If the clearance between the actuator boss 11 and the actuator boss 11 changes and the center of the actuator is tilted, the magnetic disk 9 and the information track on the magnetic disk 9 will be misaligned, making it impossible to position the desired information track. An off-track phenomenon will occur.

This thermal off-track (approximately 1 micron) does not pose a particular problem in conventional magnetic disk drives because the track density is relatively low.
), the value becomes non-negligible and becomes a problem in the seek operation.

Also, there are rotary actuators that do not apply radial preload to the bearing, but it is necessary to apply at least axial preload, so there is a radial clearance between the bearing and the fixed shaft or between the bearing and the actuator. Therefore, even if the radial preload direction does not change with the seek operation as described above, the position of the magnetic head may shift due to, for example, a shock during the seek operation.

SUMMARY OF THE INVENTION An object of the present invention is to prevent a transducer from being misaligned with respect to a recording medium due to a seek operation even in a recording/reproducing apparatus in which information tracks have a high density.

[Structure of the Invention] (Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides a system in which a transducer for recording and reproducing information on a recording medium is mounted around a fixed axis using a ball bearing. In a rotary actuator of a recording/reproducing device that is rotatably supported, a preload spring (preload means) that applies a radial preload to the ball bearing is provided on the fixed shaft side.

(Function) With the above configuration, even if the actuator rotates during seek operation by the transducer, the preload spring that applies preload to the ball bearing in the radial direction moves because it is on the fixed shaft side. Therefore, the preload direction on the ball bearing does not change and remains constant. As a result, even if there is a temperature change, misalignment between the transducer and the information track during a seek operation is prevented.

(Example) Hereinafter, an example of the present invention will be described based on FIGS. 1 to 5.

1 to 3 show a first embodiment of the present invention, and the first embodiment will be described with reference to the above-mentioned FIGS. 1 to 3 and FIG. 6 used in the conventional example.

The actuator arm 7 has a boss portion 11 rotatably supported via a ball bearing 15, 17 around a fixed shaft 13 in the vertical direction fixed to a connecting plate 31, and is driven by a drive motor 5 consisting of a voice coil motor. Fixed shaft 13
It is configured to rotate around the center. A magnetic head 1 as a transducer is provided at the tip side of each actuator arm 7 via a suspension 3, and a magnetic disk 9 as a rotating recording medium is interposed between each of these magnetic heads 1. is moved to an arbitrary position on the surface of the magnetic disk 9 to record and reproduce information.

Ball bearings 15 and 17 are provided at the upper and lower parts of the fixed shaft 13 at a predetermined interval.

The lower ball bearing 17 has an inner ring 33 and an outer ring 35.
The inner ring 33 is in contact with the lower surface of the stopper portion 37 formed at the lower part of the fixed shaft 13.
After assembly, it is fixed by means such as adhesive. The outer ring 35 is fitted into the boss hole 39 in a state in which the outer ring 35 is in contact with the top surface of a stopper 41 protruding from the bottom of the boss hole 39 of the boss portion 11.

On the other hand, the upper ball bearing 15 has an inner ring 43 and an outer ring 45, and the inner ring 43 is fitted into the fixed shaft 13.
The outer ring 45 is fitted into the boss hole 39 and is in contact with the lower surface of a presser plate 47 attached to the upper surface of the boss portion 11. After assembly, the outer ring 45 and the boss portion 11 are fixed by adhesive or other means. .

A stepped portion 49 is formed approximately in the center of the fixed shaft 13 between the two ball bearings 15, 17 so that the ball bearing 15 side has a smaller diameter. This stepped portion 49 and the inner ring 43
A coil spring 51 is provided between the inner ring 43 and the fixed shaft 13 to apply a preload upward in the axial direction of the fixed shaft 13 . Further, the fixed shaft 13 is formed with a cutout surface that becomes a band-shaped flat part 53 from a position near the ball bearing 17 on the lower side of the stepped part 49 to the upper end. The flat portion 53 is formed on the surface of the fixed shaft 13 on the magnetic head 1 side, and is arranged so that the axial center of the fixed shaft 13 is approximately at the center of the seek range of the magnetic head 1 in the radial direction with respect to the information track on the magnetic disk 9. The structure is perpendicular to the connecting straight line.

In the flat part 53, the lower side of the step part 49 protrudes with a smaller cutout amount than the upper side of the step part 49, and the lower end of a leaf spring 55 as a preloading means is attached to this protruding part with a screw 57. ing. Since the leaf spring 55 is attached to the protruding portion, a gap 59 is formed between the fixed shaft 13 above the step portion 49 and the leaf spring 55. The upper end of the leaf spring 55 reaches the upper end of the ball bearing 15, and on the ball bearing 15 side of the leaf spring 55 near the upper end there is a synthetic resin (for example, plastic) pressing member with a spherical tip. A portion 61 is attached, and the leaf spring 55 is pressed against the inner ring 43 via the portion 61.
A preload is applied in the radial direction.

In the rotary actuator of the recording/reproducing apparatus having such a configuration, when the actuator arm 7 rotates around the fixed shaft 13 in order for the magnetic head 1 to perform a seek operation with respect to the magnetic disk 9, the leaf spring 55 moves toward the fixed shaft 13. Since it is provided, it does not move, and therefore, the direction of preload applied by the leaf spring 55 to the ball bearing 15 toward the magnetic disk 9 does not change and is always constant regardless of the seek position. Since this preload direction is approximately at the center of the seek range, for example, when the magnetic head 1 is sought near the outer circumference side or the inner circumference side of the magnetic disk 9, the inner ring 43 and the fixed shaft 13 may be damaged due to temperature changes. Even if the clearance of the magnetic head 1 and the information track on the magnetic disk 9 changes, and as a result, the actuator arm 7 tilts in this direction, a relative positional shift between the magnetic head 1 and the information track on the magnetic disk 9 does not occur, and the thermal off-track is maintained regardless of the seek position. becomes less likely to occur.

Coil spring 51 that applies preload to the inner ring 43 in the axial direction
is provided on the fixed shaft 13 side, so even if the actuator arm 7 makes seek rotation at high speed, the rotational moment corresponding to its acceleration/deceleration is not transmitted to the coil spring 51.
Therefore, relatively low-frequency transient vibrations of the coil spring 51 do not occur, and vibrations of the actuator arm 7 are suppressed, making high-speed seek possible. For this reason, the coil spring 5
1 can be used with a small spring constant, and even if manufacturing errors occur, fluctuations in the preload force can be suppressed to a small level.

The contact portion of the leaf spring 55 side to the ball bearing 15 is the pressing portion 61 made of synthetic resin, so even if the actuator arm 7 vibrates, this vibration will be caused by the pressing portion 61.
is absorbed, making high-speed seeking even easier.

In addition, here, the ball bearing 15.17 and the fixed shaft 13 are both made of iron-based materials, and there is almost no difference in thermal expansion coefficient between the two, so the fixed shaft 13 and the inner ring 43 are
The change in clearance itself is small, making it even more difficult for thermal off-track to occur.

The actuator, including the actuator arm 7 and boss portion 11, is often made of lightweight magnesium alloy or aluminum alloy to enable high-speed seeking.
In such a case, there is a risk that a large clearance will occur between the actuator and the iron-based bearing outside 1iii45 due to temperature changes, but since adhesive is poured into this clearance, this will reduce the clearance. The change in the temperature is suppressed, and the occurrence of thermal off-track is prevented.

FIG. 4 shows a second embodiment of the invention.

This embodiment uses a coil spring 63 in place of the leaf spring 55 of the first embodiment. The coil spring 63 is housed in a small hole 65 formed in the radial direction of the fixed shaft 13, and a spherical pressing portion 67 made of synthetic resin is provided between the coil spring 63 and the inner ring 43. ing. As in the first embodiment, the direction of preload on the ball bearing 15 is on a line connecting approximately the center of the seek range and the axis of the fixed shaft 13. Therefore, in this case, as in the first embodiment, thermal off-track is less likely to occur, but in addition, the coil spring 65 that applies preload in the radial direction and the coil spring 51 that applies preload in the axial direction can come into contact with each other. Therefore, mutual interference between the two does not occur, and vibration of the actuator arm 7 is reliably suppressed.

FIGS. 5(a) to 5(c) show a third embodiment of the present invention. In this embodiment, a substantially C-shaped spring 7o is used in place of the leaf spring 55 of the first embodiment. The C-shaped spring 7o is made of a plate-like member made of metal or the like, which is curved into a substantially C-shape so as to have an open part 73 in a part of the circumferential direction of the cylinder. It is shaped like this.

By having the open part 73, the spring 7o only needs to be around 180° to 220° with respect to the entire circumference of the cylindrical body.Such a C-shaped spring 7o can be attached to the shaft 13 as shown in FIG. The end portion 72 of the spring 70 is arranged so as to abut on a locking portion 71 formed by reducing the diameter of the semicircular portion facing the ball bearing 15 of the spring 70 . As a result, the spring 7o sandwiched between the inner ring 43 of the ball bearing 15 and the locking part 71 is elastically deformed so that the entire spring 7o is submerged, thereby applying a preload to the ball bearing 15. Note that the preload direction of the ball bearing 15 is on a line connecting approximately the center of the seek range and the axial center of the fixed shaft 13, as in the first embodiment. Even with such embodiments, the same effects as those of the above-mentioned embodiments can be expected.

Furthermore, the preloading means of the present invention is not limited to springs, and it is also possible to utilize fluid pressure differences, magnetic repulsion, and the like.

[Effects of the Invention] As explained above, according to the present invention, the preload means for applying radial preload to the ball bearing is provided on the fixed shaft side, which is the rotation center of the actuator, so that the actuator does not perform the seek operation. Therefore, even when the transducer rotates, the preload direction remains constant regardless of the seek position. Therefore, even if there is a temperature change, there will be no misalignment between the transducer and the information track position on the recording medium, that is, thermal off-track will not occur. Easily adapts to higher recording densities.

[Brief explanation of drawings]

FIG. 1 is a side sectional view of the main parts according to the first embodiment of the present invention, FIG. 2 is a right side view of the fixed shaft portion of FIG. 1, and FIG. 3 is an overall sectional view of the first embodiment. 4 is a side sectional view of the main part according to the second embodiment of the invention, FIG. 5(a) is a side sectional view of the main part according to the third embodiment of the invention, and FIG. 3
A perspective view of the preloading means used in the embodiment, FIG. 5(c) is a cross-sectional view of the main part taken along line A-A in FIG. 5(a), and FIG. 6 is the inside of a magnetic disk device according to a conventional example. The perspective view and FIG. 7 are cross-sectional views of the device. 1... Magnetic head (transducer) 7 - Actuator arm 9... Magnetic disk (recording medium) 13... Fixed shaft 15... Ball bearing 55... Leaf spring (preloading means) 63 ...Coil spring (preload means) 70...C-shaped spring (preload means)

Claims (2)

[Claims] (1) In a rotary actuator for a recording/reproducing device in which a transducer for recording and reproducing information on a recording medium is rotatably supported around a fixed shaft by a ball bearing, a radial preload is applied to the ball bearing. A rotary actuator for a recording/reproducing device, characterized in that a preload means for applying a pressure is provided on the fixed shaft side. (2) The recording and reproducing apparatus according to claim 1, wherein the preload direction by the preload means is set on a straight line connecting approximately the center of the seek range for the information track on the recording medium and the axis of the fixed shaft. rotary actuator.