JPH01204276A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To cause normal unbalance power correction by a torque to be enough by setting the spring constant of a twisting coil spring to a suitable value and causing a revolving load torque around shaft to be a constant value. CONSTITUTION:The value of a revolving torque B by a twisting coil spring 4 is changed according to a radius direction position. However, since the torque is used in the elastic limit of the spring, the change of the value has linearity. The difference of the respective values of the revolving torque B in inner circumference and outer circumference positions by the twisting coil spring 4, namely, the inclination of the revolving torque straight line B is changed like a real line by selecting the spring constant of the twisting coil spring 4. Thus, the revolving load torque around shaft, which is the sum of the revolving torque by the twisting coil spring and the movable part gravity direction component torque of a rotary actuator 3, is caused to be always constant and the correction to a radius direction torque change can be made enough.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to a magnetic disk drive in which the rotary load torque of a rotary actuator for swinging a magnetic head is kept constant.

[Conventional technology]

Figure 2 u, example t Mitsubishi Electric Wave iV. 7, 59.412
゜1985, shown on page 17. This is a schematic diagram of a conventional magnetic disk device. In Fig. 92, (1) is a magnetic disk that rotates in a vertical plane and records each piece of data, and (2) is a magnetic disk that records data on the magnetic disk. A magnetic head that writes data on a magnetic disk.

(3) is a rotary actuator for positioning the magnetic head on a predetermined track of the magnetic disk; it includes a housing (5a), an arm (3b) for mounting the magnetic head (2), and Directly connected coil (3c), f8 magnetic path (3d) and 2 rotating shafts (
3e), and when the coil (3C) is energized, f
c The rotating shaft (3e) is swung in the vertical plane according to the magnitude and direction of the current. Further, a twist coil spring (4) is disposed coaxially with the rotating shaft (3e), and
As the name suggests, this twisted coil spring (4) does not utilize the elasticity of the coil spring in the direction of expansion and contraction, but rather utilizes the elasticity of the coil in the direction of winding.

The magnetic disk 11) and the magnetic head (2) contact each other to start and stop the so-called OSS (Contact 5tar).
In a magnetic disk drive of the t-13top) type, when the magnetic head+2tit device is stopped, it retreats to a specific location outside the data recording range called the tract zone, but in this example, this specific location is placed on the magnetic disk (top). ) is shining in the inner peripheral area. The twist coil spring (4) is a mechanism that applies rotational torque to move and position the 8-air head (2) in the retract zone. On the other hand, the center position of the movable part of the rotary actuator (3), which is composed of an arm (3b) including a magnetic head (2) and a coil (6c), is usually located at the rotation axis (3e) due to the material of the component parts.
The arm (3b) is set to be offset from the center of the arm (3b) toward the tip thereof. Therefore, around the rotation shaft (30), a shaft rotation load torque is generated which is the sum of the movable part gravity direction component torque shown by arrow A in Fig. 2 and the rotation torque due to the twist coil spring (4). .

Figure 3 shows the rotational load torque around this axis on the magnetic disk (1).
Fig. 2 shows the rotational torque (B) generated by the twisting coil spring (4).
increases from the inner circumference to the outer circumference of the magnetic disk (1), while the movable part gravity direction component torque (AJ indicates the opposite direction around 1. Therefore, the rotation around the axis which is the sum of the above two components) In the example shown in FIG. 3, the load torque (C) shows a direction of l!#I@1 as it goes from the outer circumference toward the inner circumference.

By the way, when viewed from the servo control system of the disk device, the m rotational load torque tc+ti is a steady unbalanced force applied to the rotary actuator (3). Therefore, the disk drive is equipped with a mechanism for correcting this unbalanced force, and FIG. 4 shows a block diagram of the servo control system.

In FIG. 4, 11) is a magnetic disk, (2) is a magnetic head, +3) is a rotary actuator, and (4) is a twist coil spring. The position information detected by the magnetic head (2) is converted into a position error signal (51) by a two-position error signal detection circuit (5). This position error signal (51) is the track following allocation time '#! r+61 and a signal input to the seek control circuit (7), and processed by the track following side leg circuit (6) when the magnetic head (2) is in an on-track state (positioned on the center edge of the magnetic track). (61) is a fcla ki head (
2) moves between magnetic tracks, the signal (71) processed by the seek control circuit (7) is selected by the motor switching circuit (8) and becomes the feedback control signal (81).This feedback The side end signal (81) and the constant voltage signal (91) output from the constant voltage generation circuit w1t9) are added by the adder α1.

input to the power amplifier αυ. This power amplifier aυ
is the drive current (111) required to drive the magnetic head (2)
is supplied to the rotary actuator (3). The rotary actuator (3) receives this input drive current (11
1) and positions the a-air head (2) on a predetermined magnetic track using a closed loop ff1lJn. The constant voltage generating circuit (9) is provided to correct the steady unbalanced force described above.

[The lesson that the invention attempts to solve]

Since conventional magnetic disk drives have correction circuits that use constant voltage signals as described above, no consideration is given to changes in radial torque when it comes to correction of steady unbalance factors, that is, shaft rotational load torque. Therefore, the correction was not sufficient.

Furthermore, this correction is insufficient.

Servo IIJ There was a point where the settling characteristics of the groaning system immediately after the positioning operation were poor, resulting in an increase in the positioning time.

The present invention has been made to solve the above-mentioned problems, and an object thereof is to obtain a magnetic disk device that has good settling characteristics immediately after a positioning operation of a servo control system (2) and has a short positioning time.

[Means to solve the problem of poor section]

The disk device according to the present invention can be achieved by appropriately setting the spring constant of the twist coil spring.

The correction for the radial torque change in the rotational load torque of the shaft is made more effective.

[Effect]

The twist coil spring in this invention can be used to reduce the rotational load torque around the axis, which is the sum of the rotational torque due to the twist coil spring and the component torque in the direction of gravity of the movable part of the rotary actuator, by selecting a nine-way spring constant. It acts so that the load torque is always constant and does not depend on the radial position associated with the rocking of the actuator.

[Embodiments of the invention]

An embodiment of this invention will be described below. The structure of the magnetic disk device according to the present invention is the same as that of the conventional device shown in FIGS. 2 and 4, and will therefore be omitted. Figure @1 is obtained according to one embodiment of the present invention. FIG. 4 is a diagram showing the relationship between rotation load torque (C) and the radial position of the magnetic disk +11, corresponding to FIG. 3 above. In Figure 1, the twisted coil (
4], the value of the rotational torque (11) changes depending on the radial position.

Since it is used within the elastic limit of the spring, the change in its value is constant. In addition, the difference between the respective values of the rotational torque (B) at the inner and outer circumference positions due to the twist p large coil spring (4), that is, the change in rotational torque between the inner and outer circumferences, is the so-called twist coil spring rotation torque straight line ( The slope of B) can be changed by selecting the spring constant of the twist coil spring (4), for example, from the dotted line in the figure to the solid line.

Therefore, it is possible to select the spring constant of the twist coil spring (4) such that the shaft rotation load torque (C) of the rotary actuator (3) is always constant over the swing range between the inner and outer circumferences. It is understood that this is also possible.

The difference between the absolute value of the rotational torque T of the twist coil spring (4) and the twist angle σ is 1TI=1σ0T.

However: spring constant Initial torque at To20=0 The following relationship is established. Therefore, in Figure 1.

In order to make the rotating load torque (C) around the axis a constant value, that is, to make the dotted line in the figure the actual machine, twist coil springs (4
This can be achieved by appropriately reducing the spring constant k of ).

[Effects of the Invention] As described above, according to the present invention, the spring constant of the twist coil is set to an appropriate value, and the e-turn rotation load torque is configured to be a constant value.

The steady unbalanced force correction by the above torque is sufficient, and the settling characteristics immediately after the positioning operation are improved (
9. A magnetic disk device with short positioning time can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the shaft rotation load torque characteristics according to an embodiment of the present invention, and FIG. 2 is a diagram showing the configuration of a magnetic disk device common to the conventional and the present invention. FIG. 3 is a diagram showing the shaft rotation load torque characteristics of a conventional device, and FIG. 4 is a diagram showing the servo i! of a magnetic disk device common to the conventional device and the present invention. FIG. 1 is a block diagram showing a 1jXI system. In the figure, 11) is a magnetic disk, and (2) is a magnetic head. (3) is a rotary actuator, (3e)
is its rotation axis, (4) is the twist coil spring, (A) is the component torque in the direction of gravity of the movable part of the rotary actuator, (
B) is the rotational torque of the twist coil, and (C) is the rotational load torque of the cap rotational force.
indicates a considerable portion. Dai Atsuto Oiwa Ruru No. 1 Figure narrow mouth / 1 rotation Torf bu L@Hankei No. 2im A. Movable:
spontaneous)

Claims (1)

[Claims] A magnetic disk that rotates in a vertical plane, a magnetic head that reads data on the magnetic disk or writes data on the magnetic disk, and a rotary actuator that positions this magnetic head on a predetermined track of the magnetic disk. , in a magnetic disk device comprising a torsion coil spring provided on the rotating shaft of the rotary actuator, the spring constant of the torsion coil spring is the sum of the component torque in the direction of gravity of the movable part of the rotary actuator and the rotational torque by the torsion coil spring. A magnetic disk drive characterized in that the rotational load torque around an axis is set to be constant over a swing range of the rotary actuator.