JPH08221912A - Head actuator for magnetic disk device - Google Patents

Abstract

PURPOSE: To obtain an actuator for which a large range of head movement is adoptable and in which the influence of the friction of rolling bearings does not appear to a head positioning servo system, by disposing the head which is supported by rolling bearings and is made of elastic materials. CONSTITUTION: Two pieces of the rolling bearings 6 consisting of ball bearings, etc., are disposed in the axial direction of a pivot shaft 5 to rotationally support a pivot housing 7. A flexible supporting member 8 consists of a plate material of a stainless steel material, etc., having elasticity and is formed into a parallel spring structure obtd. by combining the material with leaf springs 8a and 8b increased in the flexible rigidity by bending their central parts. The beginning of the movement of the head actuator 2 is governed by the elasticity of the member 8 and the influence of the static friction toque of the bearings 6 does not appear. Then, the head positioning servo system having the actuator 2 is constituted as a control system without having a blind zone. As a result, the head 14 is positioned even by the microcurrent supplied to a coil 10 and the positioning with high accuracy is made possible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk device.

[0002]

2. Description of the Related Art In a magnetic disk apparatus, a suspension (load arm) having a head for recording / reproducing information on a disk at its tip is fixed to one end of a carriage, and a voice generating a driving force at the other end of the carriage. A coil actuator, which is a constituent member of a coil motor, is attached, and a head actuator that rotatably supports a carriage by a rolling bearing is mounted. These coils and head were arranged on opposite sides of the rolling bearing.
The head actuator supplies a current based on a signal reproduced by the head to a coil to oscillate the carriage to position the head at a predetermined position (track where information is recorded) on a disk by a head positioning servo system. Was controlled. The rolling bearing that rotatably supports the head actuator has a static friction torque due to minute slip and elastic hysteresis at the contact portion between the inner ring and the outer ring and the rolling element and the viscosity of the filled grease. The non-linear characteristics caused by this static friction torque affect
The head positioning servo system has a dead zone, which has been a factor that hinders the accuracy of head positioning.

As a solution to this problem, a structure in which the head actuator is supported only by an elastic member has been proposed. This is an elastic structure supported by parallel springs and is disclosed, for example, in US Pat. No. 4,868,696.

[0004]

The structure in which the head actuator is supported by the rolling bearing has a feature that the head moving range can be wide, but as mentioned above, there is a problem of the dead zone. When the driving current is small, the operation is performed within the dead zone, and there is a problem that the carriage cannot be rotated corresponding to the supplied driving current and the head positioning control cannot be performed. Further, this dead zone has a problem that the higher the density of recording, the more adversely affects the head positioning due to the phenomenon of off-track, which hinders the realization of high density recording. On the other hand, the parallel spring structure in which the head actuator is supported only by the elastic member does not have non-linearity such as static friction torque and is therefore considered to be a good mechanism. However, since the head moving range of the magnetic disk device is large compared to the device size, and the size of the supporting member is limited by the device size, excessive bending stress is generated in the supporting member during operation, causing problems such as fatigue fracture. This is a mechanism that is difficult to realize.

It is an object of the present invention to provide a head actuator for a magnetic disk device, which has a large head movement range and in which the effect of friction of the rolling bearing does not appear in the head positioning servo system.

[0006]

The present invention solves the above problems by supporting a head actuator with a structure in which a rolling bearing and an elastic member are arranged in series. That is, the structure in which the head actuator is supported only by the elastic member does not have nonlinearity such as static friction torque, and is therefore considered to be a good mechanism. However, since the head moving range of the magnetic disk device is larger than the device size, and the size of the supporting member is limited by the device size, excessive stress is generated in the supporting member during operation, causing problems such as material destruction. Yes, it is difficult to realize. Further, the conventional structure in which only the rolling bearing is supported has a feature that the head moving range can be wide, but has a problem of dead zone. In the present invention, the support structure takes advantage of both structures. That is, by providing the head ahead of the elastic member (supporting member) supported by the rolling bearing, it is possible to provide a head actuator for a magnetic disk device in which the nonlinear characteristics of the rolling bearing do not appear in the head positioning servo system.

[0007]

When the movement of the head is small, the elastic member is deformed to position the head, and in the seek operation in which the head is largely moved, the rolling bearing is rotated and the support member is deformed to position the head. At the start of the seek operation, the head begins to move due to the deformation of the support member, and further, the rolling bearing where a driving torque exceeding the static friction torque acts on the rolling bearing causes the head to reach the target track. As described above, when the driving torque is small, the head moves due to the deflection of the support member, and thus the non-linearity due to the static friction torque of the rolling bearing does not appear in the motion of the head.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

A head actuator 2 of the present invention is shown in FIG. FIG. 2 shows a magnetic disk device 1 equipped with this head actuator 2. FIG. 2 shows a magnetic disk device 1
It is a top view which removes the lid of the upper side of and shows arrangement | positioning of a mechanism.

The disk 3 is attached to a spindle motor (not shown) fixed to the base 4 and rotates at a constant angular velocity. A head 14 positioned on the disk 3 for recording / reproducing information is attached to the end of the head actuator 2. The head actuator 2 includes a pivot housing 5 fixed to a base 4, a pivot housing 7 rotatably mounted about a pivot shaft 5 via a rolling bearing 6, one end fixed to the pivot housing 7 and the other end carriage. A flexible support member 8 fixed to the carriage 9, a coil 10 which is a component of a driving means, which is disposed on the opposite side of the pivot shaft 5 with respect to the carriage 9, and which is adhered to an end portion of the carriage 9, and the carriage 9. And a load arm 13 having a head 14 at the tip attached to the end of the. In this embodiment, a ball bearing is used as the rolling bearing 6, and two ball bearings are arranged in the axial direction of the pivot shaft 5.
The pivot housing 7 is rotatably supported. The flexible support member 8 is made of an elastic plate material such as stainless steel,
As shown in the figure, a parallel spring structure is formed by combining leaf springs 8a and 8b whose central portions are bent to increase the bending rigidity of the members. The rigidity of the support member 8 is designed to be small in the radial direction of the disk (track direction) and large in the direction perpendicular thereto, so that the head 14 and the disk 3 can be connected.
It has a mechanism that moves parallel to the plane. Coil 1
Reference numeral 0 forms a voice coil motor 15 which is a driving means by the magnet 11 and the yoke 12, and generates a thrust by supplying a driving current to the coil 10, and by the deformation of the support member 8 and the rotation around the pivot shaft 5, The head 14 is positioned on the disk 3 via the carriage 9 and the load arm 13. The head actuator 2 is supported by the rolling bearing 6 and the support member 8 and swings by the thrust generated by the voice coil motor 15.

Further, the thrust force of the voice coil motor 15 for swinging the head actuator 2 is generated by the pivot shaft 5.
Since it acts as a rotating torque, when the thrust generation point is farther from the pivot shaft 5, that is, when the arm length is longer, the same thrust motion is required, and a small thrust force is sufficient. The drive current supplied can be reduced. As shown in FIG. 1, a rolling bearing 6 for supporting a head actuator 2 and a supporting portion composed of a supporting member 8 and a head 1
4, coil 1 of voice coil motor 15 which is a driving means
By arranging in order of 0, the length of the arm is greatly taken,
The seek operation is possible with a small drive current.

This has the effect of reducing the power consumption during the seek operation.

In the seek operation for moving the head 14 to the target track, the head actuator 2 starts moving by supplying a drive current to the coil 10. Initially, due to the static friction torque of the rolling bearing 6, the rotational movement around the pivot shaft 5 does not occur, and the head actuator 2 starts to move due to the deformation of the support member 8 in the track direction, and the deformation amount increases. Voice coil motor 1
If the thrust of 5 continues, the driving torque exceeding the static friction torque acts on the rolling bearing 6, and the pivot housing 7
Begins to rotate. Due to the occurrence of this rotational movement, the deformation of the support member 8 is slightly alleviated, and the support member 8 maintains the deformation corresponding to the dynamic friction torque of the rolling bearing 6,
The head actuator 2 rotates. When the head 14 reaches the target track, the head actuator 2 performs a track following operation. This track following operation is performed by the support member 8
The deformation of causes the head 14 to follow the target track.

Further, the head 14 has an adjacent track or 2
Since the short seek operation of moving to a track separated by 4 tracks does not require a large thrust, the head 14 is positioned only by the deformation of the support member 8.

At the beginning of the movement of the head actuator 2,
It is governed by the elasticity of the support member 8, and the influence of the static friction torque of the rolling bearing 6 does not appear. Therefore, it can be seen that the head positioning servo system including the head actuator 2 is a control system having no dead zone. As a result, the head 14 can be positioned even with respect to the minute current supplied to the coil 10, which enables highly accurate positioning, and high-density recording in the magnetic disk device 1 can be realized.

[0016]

According to the present invention, high-density recording can be realized by the magnetic disk device equipped with the head actuator in which the static friction torque characteristic of the support mechanism does not appear.

[Brief description of drawings]

FIG. 1 is a perspective view of a head actuator showing an embodiment of the present invention.

FIG. 2 is a plan view of a magnetic disk device equipped with the head actuator of FIG.

[Explanation of symbols]

1 ... Magnetic disk device, 2 ... Head actuator, 3
... disk, 4 ... base, 5 ... pivot shaft, 6 ... rolling bearing, 7 ... pivot housing, 8 ... support member, 9 ...
Carriage, 10 ... Coil, 11 ... Magnet, 12 ... Yoke, 13 ... Load arm, 14 ... Head, 15 ... Voice coil motor.

Claims (1)

[Claims] 1. A magnetic disk device equipped with a head actuator for positioning a head for recording / reproducing information on a rotating disk, comprising: a pivot shaft fixed to a base; and a rolling bearing provided on the pivot shaft. A pivot housing rotatably supported by the rolling bearing, a flexible support member having one end fixed to the pivot housing, a carriage having the other end of the support member fixed, and a load arm having the head And a drive means for swinging the carriage, wherein the drive means and the load arm are attached to the carriage, respectively.