JPH01119970A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To prevent the damage of a magnetic disk and to speedily detect runaway by detecting the runaway of a magnetic head at the time of shift- controlling when runaway starts and stopping the driving of an actuator. CONSTITUTION:The magnetic head 2 reads servo information from the magnetic disk 1 to which servo information is recorded, and the actuator 4 drives the magnetic head 2, whereby an abnormality detection circuit 25 judges that the shifting speed of the actuator 4 exceeds a previously decided limited speed based on the output of the magnetic head 2. A switch 14 stops the driving of the actuator 4 after it receives the signal of the abnormality detection circuit 25. Thus, speedy runaway detection is attained and the damage of the magnetic disk can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a magnetic disk device used in electronic computers, computer peripheral terminals, and the like.

[Conventional technology]

FIG. 2 is a schematic diagram showing a conventional magnetic disk device disclosed in, for example, Japanese Unexamined Patent Publication No. 62-75969. In the figure, (11 is a magnetic disk that records information, (2) is a magnetic head that writes and reads information on the magnetic disk (11), (3) is an access arm that supports and moves the magnetic head (2), ( 4) is a voice coil motor (hereinafter referred to as VCtM) as an actuator that drives the access arm (3), +51 is a voice coil, (61
are pre-recorded servo data areas, (7) and (81
are the guard band areas on the outer and inner peripheries, (9) and 0 V OM (the runaway stopper provided at 41, αυ
is a rotation speed 0 position and speed detection circuit, α2 is a magnetic disk rotation speed check circuit, α stage is an actuator control circuit that controls the VCM (41), and a4 is a switch that opens and closes the power supply 4 that supplies power. .

Next, the operation will be explained. When the magnetic head (2) is in the servo data area (61) of the magnetic disk (1), the outer and inner guard band areas (71+81), the servo information is read by the magnetic head (2) and rotation detection is performed. However, when runaway occurs, the access arm (3) hits the runaway prevention dashi bar (91 (corresponds to 1). At this time, if the access arm (31) hits weakly, the magnetic head (21 is the guard band on the outer and inner circumference) Area (71181
However, if it hits hard, it will fall out of the guard band area +71181. Therefore, although the rotation was accurately detected using servo information, when the magnetic head (21) moves out of the guard band area +71 to +81, the servo information is lost and it becomes impossible to check the rotation speed. Judging by the circuit α power, the switch (1
41 cuts off the power supply from the power source (151).

As mentioned above, when the access arm +31 weakly hits the runaway stopper (91 (11)), the busy magnetic head (21
It was necessary to make adjustments so that the ball would not fall outside the guard bird area +71 +81 on the outer and inner peripheries, and would fall off if it was hit hard.

[Problem that the invention seeks to solve]

Conventional magnetic disk drives are configured as described above, so adjustments must be made so that if the access arm strongly hits the runaway prevention damper, it will come out of the guard band area, and if the adjustment is insufficient, runaway may occur. There were problems such as damage to the magnetic disk if the disk was moved over the disk.

The present invention has been made to solve the above-mentioned problems, and aims to provide a magnetic disk device that can quickly detect runaway and prevent damage to the magnetic disk.

[Means for solving problems]

In the magnetic disk device according to the present invention, a magnetic head reads servo information from a magnetic disk on which servo information is recorded, an actuator drives the magnetic head, and an abnormality detection circuit detects the moving speed of the actuator based on the output of the magnetic head. It is determined that the speed exceeds a predetermined limit, and the switch stops driving the actuator upon receiving a signal from the abnormality detection circuit.

[Effect]

In the magnetic disk drive of the present invention, the abnormality detection circuit determines that the actuator has run out of control when the actuator movement speed exceeds a predetermined limit speed, outputs a signal indicating that there is an abnormality, and the switch is activated. Upon receiving this signal, the power supply to the actuator is cut off. [Published Embodiment] An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, ill~+81. (L3) to CI5 are similar to the conventional inspection apparatus. ① is a position signal reproducing circuit that reproduces a position signal from the read waveform of servo information of the magnetic head (2); c! D is a speed detection circuit that detects the moving speed of the magnetic head (2) by time-differentiating the position signal, @ is a speed reference generating circuit that provides a profile of the moving speed of the magnetic head (2), @ is a generating circuit Therefore, a speed error detection circuit detects the difference between the generated speed reference and the actual moving speed detected by the detection circuit +21+, and (2) is the limit that generates a limit speed signal that exceeds the maximum speed given by the generation circuit @. The speed generation circuit (■) is an abnormality detection circuit that detects whether the actual moving speed exceeds the limit speed.

Next, the operation will be explained. Normally, in the case of movement control of the magnetic head (21), a multi-position signal is reproduced by a reproducing circuit (2), and this position signal is time-differentiated by a detection circuit (2υ) to generate a speed signal.The generated speed signal The error detection circuit detects the difference between the speed reference and the speed reference generated by the generation circuit @.Then, in response to the signal detected by the error detection circuit, the actuator control circuit a3 controls the magnetic head (21 V CM (41 is drive-controlled. V CM
If [41 runs out of control, the movement control of the magnetic head (2) becomes impossible, but the speed signal can be accurately detected by the detection circuit c2D. And the speed at the time of runaway is the limit speed generation circuit c! When the abnormality detection circuit detects that the speed is higher than that generated at 41, the power supply is cut off to stop supplying power to the device.

In the above embodiment, when runaway is detected, the power supply is cut off, but it goes without saying that the same effect can be achieved by stopping the movement of the actuator, such as by cutting off the power supply to the actuator of VC3M 141. do not have.

〔Effect of the invention〕

As described above, according to the present invention, runaway during control of the movement of the magnetic head is detected at the point when the runaway starts, and the drive of the actuator is stopped, so damage to the magnetic disk can be prevented. This eliminates the need for a runaway prevention damper and has the effect of quickly detecting runaway.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram showing a schematic configuration of a magnetic disk device according to an embodiment of the present invention, and FIG. 2 is a schematic diagram showing an access system of a conventional magnetic disk device. In the figure, (11 is a magnetic disk, (21 is a magnetic head, (4) is a voice coil motor (actuator),
(6) is the servo data area (servo information), (71,
181 is the guard band area (servo information), (141
is a switch, and 4 is an abnormality detection circuit. In each figure, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] A magnetic disk on which servo information is recorded, a magnetic head that reads the servo information from the magnetic disk, an actuator that drives the magnetic head, and a limit speed at which the movement speed of the actuator is predetermined based on the output of the magnetic head. An abnormality detection circuit that determines when the
A magnetic disk drive characterized by comprising a switch that stops driving the actuator in response to a signal from the abnormality detection circuit.