JPH0316067A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To prevent a magnetic disk from flawing even without any anti- runaway damper by detecting an actual driving speed of the magnetic head based on a current to flow in an actuator, comparing the driving speed with a predetermined limit speed and detecting an abnormality of the driving speed of the magnetic head accordingly. CONSTITUTION:When a voice-coil motor 3 is run away, the moving speed of the magnetic head 1 is detected by a speed detecting circuit 12 based on the current to flow the voice-coil motor 3, and its speed signal is supplied to an abnormality detecting circuit 14. Then, when it is detected by the abnormality detecting circuit 14 that the speed signal is higher in level than a limit speed signal supplied from a limit speed generating circuit 13, a switch 10 is operated to cut off a power source 11, and hence the power source is stopped in its supply to the magnetic disk device. By this method, the runaway is detected at the time of its starting, so that the magnetic disk is prevented from flawing. In addition, the need of the anti-runaway damper is eliminated.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a magnetic disk device used in electronic computers, peripheral terminals, etc. In particular, it concerns the runaway protection function of magnetic disk drives. [Prior Art] The configuration of a conventional example will be explained with reference to FIG.

FIG. 4 is a block diagram showing a partial plan view of a conventional magnetic disk device disclosed in, for example, Japanese Unexamined Patent Publication No. 62-75969.

In FIG. 4, a conventional magnetic disk drive includes a magnetic head (1), an access arm (2) that supports the magnetic head (1), and a voice coil motor (actuator) connected to the access arm (2). ) (3), the voice coil (4), the runaway dampers (5) and (6) provided at both ends of the voice coil motor (3), and the rotation speed/position connected to the magnetic head (1). / speed detection circuit (7), an actuator control circuit (8) whose input side is connected to the rotation speed/position/speed detection circuit (7) and whose output side is connected to the voice coil <4), and the rotation speed/position / A rotation speed check circuit (9) connected to the speed detection circuit (7>), a switch (10) connected to this rotation speed check circuit (9), and a power supply to the entire device connected to this switch (10). and a power supply (l1) that supplies the power.

The magnetic disk D has a servo data area A and guard band areas B and C adjacent to the outer and inner peripheries of the servo data area A.

Next, the operation of the above-mentioned conventional example will be explained.

When the magnetic head (1) is located in the servo data area A or the guard band area B or C of the magnetic disk D,
The servo information is read and rotation of the magnetic disk D is accurately detected.

However, when runaway occurs, the rear end of the access arm (2) hits the runaway prevention damper (5) or (6). At this time, if the magnetic head (1) is strongly hit, the magnetic head (1) will come out of the guard band area B or C.

Then, since the servo information is lost, the rotation speed check circuit (9) operates the switch (10) and the power supply (1
Cut 1〉. Therefore, if the access arm (2) weakly hits the runaway damper (5) or (6), the magnetic head (1)
) to prevent it from coming off guard band area B or C, and to prevent it from coming off if it hits hard.
It was necessary to adjust 5) and (6>). [Problem to be solved by the invention] In the conventional magnetic disk device as described above, delicate adjustment of runaway prevention dampers (5) and (6>) was required. There was also the problem that if the runaway prevention dampers (5) and (6) were not properly adjusted, there was a risk of damaging the magnetic disk in the event of runaway. The invention was made to solve the above-mentioned problems, and an object of the invention is to obtain a magnetic disk device that can prevent damage to a magnetic disk even without a runaway damper. Means] The magnetic disk device according to the present invention includes the following means: (i) Drive control means for driving and controlling the magnetic head based on servo information recorded on the magnetic disk.

(ii). A speed detection circuit that detects the actual driving speed of the magnetic head based on the current flowing through the actuator. (iii). A limit speed generation circuit that generates the limit speed of the above magnetic head. (iv). An abnormality detection circuit that compares the driving speed with a limit speed to detect an abnormality in the driving speed of the magnetic head.

(V). Stopping means for stopping the magnetic head when this abnormality detection circuit detects an abnormality. [Operation] In the present invention, the drive control means drives and controls the magnetic head based on servo information recorded on the magnetic disk.

Further, a speed detection circuit detects the actual driving speed of the magnetic head based on the current flowing through the actuator.

Further, a limit speed generation circuit generates a limit speed of the magnetic head. Furthermore, an abnormality detection circuit compares the driving speed with a limit speed to detect an abnormality in the driving speed of the magnetic head. Then, the magnetic head is stopped by the stopping means when the abnormality detection circuit detects an abnormality.

[Embodiment] The configuration of a first embodiment of this invention will be explained with reference to FIG. FIG. 1 is a block diagram showing a first embodiment of the present invention, in which a magnetic head (1>), a voice coil motor (3), an actuator control @path (8), a switch 10> and a power supply (11>) are shown. It is completely the same as that of the conventional device described above. Although not shown, the access arm (2> and the voice coil (4>) are also the same. In FIG. 1, the first embodiment of the present invention has the following features: The same components as those of the conventional device described above, a reproducing circuit (7^) whose input side is connected to the magnetic head (i) and whose output side is connected to the actuator control circuit (8), and an actuator control circuit (8) are included.
) is connected to the speed detection circuit (12) and the limit speed generation circuit (13), and the input side is connected to the speed detection circuit (12) and the limit speed generation circuit (13>) and the switch (IO
) is connected to the abnormality detection circuit (14) on the output side. By the way, in the first embodiment of the invention described above, the drive control means of the present invention is composed of the voice coil motor (3), the regeneration circuit (7^), and the actuator control circuit (8), and the stop means is composed of the switch ( 10). Next, the operation of the first embodiment described above will be explained. To control the drive of the magnetic head (1), a position signal is normally reproduced by a reproducing circuit (7^), and based on this position signal, an actuator control circuit (8) transmits a current to a voice coil motor (
3). On the other hand, drive control of the magnetic head (1) becomes impossible if the voice coil motor (3) runs out of control.

However, the speed detection circuit (12) detects the magnetic head (1) based on the current flowing through the voice coil motor (3).
> is detected and the speed signal is sent to the abnormality detection circuit (1
4). When the abnormality detection circuit (14) detects that the speed signal is higher in level than the limit speed signal supplied from the limit speed generation circuit (13), the abnormality detection circuit (14) operates the switch (10) to cut off the power supply (11). Then, the power supply to the magnetic disk device is stopped. In the first embodiment of the present invention, when it is detected that the moving speed of the actuator exceeds a predetermined limit speed due to the current flowing through the voice coil motor (3) as described above, the power supply to the magnetic disk drive is switched off. Since the supply of magnetic disk is stopped, runaway can be detected quickly, that is, runaway can be detected as soon as it starts, and damage to the magnetic disk can be prevented.Therefore, a runaway prevention damper is no longer required. In the first embodiment, the power supply to the magnetic disk device is stopped when runaway is detected, but the same operation can be expected even if only the power supply to the actuator is cut off.Second aspect of the invention The horizontal command of the embodiment will be explained with reference to FIGS. 2 and 3.

FIG. 2 is a block diagram showing a second embodiment of the present invention, which includes a magnetic head (1), a voice coil motor (3), a reproduction circuit (78), an actuator control circuit (8), and a limit speed generation circuit. (13) and the abnormality detection circuit (14) are exactly the same as those of the first embodiment. In FIG. 2, the second embodiment of the present invention is exactly the same as that of the first embodiment described above. And the one played R (7^)
and a speed detection circuit (12^) whose input side is connected to the actuator control circuit fYJ (8) and whose output side is connected to the abnormality detection circuit (14), and an abnormality detection circuit (14).
A switch (16) whose input side is connected to the actuator control circuit (8) and the brake circuit (15) and whose output side is connected to the voice coil motor (3). The switch (16) connects the actuator control circuit (8) or the braking circuit (15) to the voice coil motor (3) in response to a control command from the abnormality detection circuit (14). FIG. 3 is a circuit diagram showing a braking circuit (15) according to a second embodiment of the invention.

In FIG. 3, the braking circuit (15) includes a braking capacitor (15a) connected to a power supply Vcc, and a switching relay (15a) connected in parallel to this braking capacitor (15a).
15b) is an elliptical precept. By the way, in the second embodiment of the invention described above, the stopping means of the present invention is controlled by the braking circuit (15) and the switch (16).

Next, the operation of the second embodiment described above will be explained. The normal operation is the same as in the first embodiment. If the access arm (not shown) goes out of control, the drive control of the magnetic head (1) becomes impossible, but the current flowing to the voice coil motor (3) or the position signal reproduced by the reproduction circuit (78) Based on either or both, the speed detection circuit (12^) detects the moving speed of the magnetic head (1),
The speed signal is supplied to the abnormality detection circuit (14). When the abnormality detection circuit (14) detects that the speed signal is higher in level than the limit speed signal supplied from the limit speed detection circuit (13), it issues a control command to the switch (16).

The switch (16) switches the braking circuit (16) based on the control command.
5) and the voice coil motor (3) are connected, and the access arm is braked. As shown in Figure 3, the voice coil (4) is normally driven and controlled by an actuator control circuit (8), and when the speed of the magnetic head (1) exceeds a limit speed, the brake is applied by a switch (16). Connected to the circuit (15).

The switching relay (15b) of the braking circuit (15) is switched by the abnormality detection circuit (14) so that current flows in the direction in which braking is applied, and the energy accumulated in the braking capacitor (15a) is transferred to the voice coil (4). The second embodiment of the present invention has a magnetic head (
1) Runaway during drive control is detected from the moment the runaway starts, and before the magnetic head (1) enters the guard band area of the magnetic disk, braking is applied and decelerated, so a runaway prevention damper is not necessary. Damage to the magnetic disk can be prevented and a highly reliable device can be realized. In each embodiment of the present invention, a speed detection circuit is provided separately, but if the drive control of the access arm is speed follow-up control, a speed detector included in the control system may also be used. ．． [Effects of the Invention] As described above, the present invention includes a drive control means for controlling the drive of a magnetic head based on servo information recorded on a magnetic disk, and a drive control means for controlling the drive of a magnetic head based on servo information recorded on a magnetic disk, and a drive control means for controlling the drive of a magnetic head based on a current flowing through an actuator. a speed detection circuit that detects speed; a limit speed generation circuit that generates a limit speed of the magnetic head; and an abnormality detection circuit that compares the drive speed and the limit speed to detect an abnormality in the drive speed of the magnetic head;
Since this abnormality detection circuit includes a stopping means for stopping the magnetic head when an abnormality is detected, it is possible to prevent damage to the magnetic disk even without a runaway damper.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a first embodiment of the present invention, and FIG.
FIG. 3 is a block diagram showing a second embodiment of the invention, FIG. 3 is a circuit diagram showing a braking circuit of the second embodiment of the invention, and FIG. 4 is a block diagram showing a partial plan view of a conventional magnetic disk device. It is a diagram. In the figure, (1) ... magnetic head, (3) ... voice coil motor, (7^) ...
・ Regeneration circuit, (8) ... Actuator control circuit, (10)
... Switch, (1l> ... Power supply, (12), (12^) ... Speed detection circuit, (13
〉 ・・・ Limit speed generation circuit, (14) ・・・
Abnormality detection circuit, (l5)...braking circuit, (16)...switch. In addition, in each figure,
The same symbols indicate the same or equivalent parts.

Claims (1)

[Claims] A drive control means for controlling the drive of the magnetic head based on servo information recorded on the magnetic disk, a speed detection circuit for detecting the actual driving speed of the magnetic head based on the current flowing through the actuator, and a speed detection circuit for detecting the limit speed of the magnetic head. an abnormality detection circuit that detects an abnormality in the driving speed of the magnetic head by comparing the driving speed with the limit speed, and stops the magnetic head when the abnormality detection circuit detects an abnormality. A magnetic disk device characterized by being equipped with a stopping means.