JPH0536009A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To prevent a read/write error or a head crush due to the influence of a dust. CONSTITUTION:When a command decoder circuit 2 receives a test pattern reading command 3 from a host device 1, a control circuit 4 controls a test pattern to be read. When a voltage level comparator circuit 6 judges that the read waveform voltage level of this test pattern is smaller than a reference voltage level 8, a spindle motor driving circuit 9 repeats the start and stop operation of the power source of a pertinent HDA spindle motor 11 several times. When this series of start and stop operation is completed, the test pattern is controlled to be read again by the control circuit 4. At that time, when the reference voltage level 8 is larger than the read waveform voltage level 7, the power source of the pertinent HDA is turned OFF in order to prevent the writing failure or the read error due to the influence of the dust stuck to a magnetic head.

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, and more particularly to prevention of write failure due to head crush caused by dust attached to a magnetic head and reduction in output of the magnetic head.

[0002]

2. Description of the Related Art Generally, when a magnetic disk drive is operating, an HDA (head disk assembly) is used.
ly) The magnetic disk plate is rotating at high speed inside,
The magnetic head positioning mechanism also operates at high speed. Therefore, the high speed rotation of the magnetic disk plate causes the HDA
Air convection occurs inside. Due to this air convection,
Dust generated by friction between metals and contact between the head and the medium, and dust contained in the air taken into the HDA from the outside circulate in the HDA. As a result, dust or dust is likely to adhere to the magnetic head when operating continuously for a long period of time. Therefore, if the drop in voltage level of the read / write waveform due to the influence of dust or dust is large, it causes a read error or write failure, and in the worst case, a failure such as head crash is likely to occur.

[0003]

In the above-mentioned conventional magnetic disk drive, dust circulating in the HDA adheres to the surface of the magnetic head, resulting in a read / write error or a write failure.
In the worst case, it had the drawback of causing a head crash.

[0004]

A magnetic disk device of the present invention comprises a read waveform voltage level confirmation means for reading a test pattern from a data surface and outputting a read waveform voltage level according to an instruction from a host device, and the read waveform voltage. Voltage level comparison means for comparing the level with a predetermined reference voltage level and for starting and stopping the spindle motor used for reading the test pattern a predetermined number of times when the read waveform voltage level is lower. ing.

The test pattern may be written in advance in a spare diagnostic cylinder on the data surface.

Further, in the magnetic disk device of the present invention, after the spindle motor has been started and stopped a predetermined number of times, the test pattern is read again by the read waveform voltage level confirmation means, and is obtained by this reading again. Stopping the operation of the spindle motor used to read the test pattern when the read waveform voltage level obtained is lower than the reference voltage level,
Moreover, it may be configured to report an abnormality to the host device.

[0007]

The present invention will be described below with reference to the drawings.

FIG. 1 shows a block diagram of an embodiment of a magnetic disk device of the present invention.

The host device 1 is a device for processing the data stored in this embodiment. When the command decoder circuit 2 of this embodiment receives and decodes the test pattern read command 3 from the higher-level device 1, it issues a read command 5 to the control circuit 4. The control circuit 4 controls so as to read the test pattern immediately after receiving the read command 5, and transmits the voltage level 7 of the read waveform of the test pattern to the voltage level comparison circuit 6. The reference voltage level 8 is a voltage level that does not cause a read error or a write failure even when a read / write operation is performed on data on the data surface at that voltage level. The voltage level comparison circuit 6 includes a reference voltage level 8 and a voltage level 7 of the read waveform of the test pattern.
When the voltage level 7 of the read waveform of the test pattern is higher, the normal operation is restored.

When the reference voltage level 8 is higher, a recovery operation command 10 is issued to the spindle motor drive circuit 9 in order to recover the read waveform voltage level lowered in level mainly due to dust adhering to the magnetic head. When the spindle motor drive circuit 9 receives the restoration operation command 10, the spindle motor drive circuit 9 completely stops the rotation of the spindle motor 11 and restarts the spindle motor 11. As a result, the magnetic head vibrates due to contact between the magnetic head and the medium. By repeating a series of operations in which the spindle motor 11 is stopped and restarted in one cycle, dust on the magnetic head is shaken off to restore the lowered read waveform voltage level. The spindle motor drive circuit 9 sends a completion signal 12 to the control circuit 4 when this recovery operation is completed.

Upon receiving the completion signal 12, the control circuit 4 controls so as to immediately read the test pattern, transmits the voltage level 7 of the read waveform of the test pattern to the voltage level comparison circuit 6, and the voltage level comparison circuit 6 causes the voltage level comparison circuit 6 to read. , The reference voltage level 8 is compared with the voltage level 7 of the read waveform of the test pattern. At this time, if the voltage level 7 of the read waveform of the test pattern is higher, the cause of the decrease of the voltage level of the read waveform is the influence of the dust adhering to the magnetic head, and the dust adhering to the magnetic head by the recovery operation. Judges that he has been shaken off and returns to normal operation.

On the other hand, when the reference voltage level 8 is higher, the spindle motor stop command 13 is transmitted to the spindle motor drive circuit 9 in order to prevent the write failure due to the decrease of the magnetic head output voltage level. The spindle motor drive circuit 9 which has received the spindle motor stop command 13 determines the spindle motor 1 of the corresponding HDA.
No. 1 is stopped, and the upper level device 1 is notified that the spindle motor 11 is stopped by the voltage level abnormal signal 14.

[0013]

As described above, in the present invention, when the spindle motor is restarted, the dust accumulated on the surface of the magnetic head is shaken off due to the contact between the magnetic head and the disk plate and the vibration of the magnetic head. As a result, there is an effect that a read error caused by dust accumulated on the surface of the magnetic head, a write failure, etc. can be prevented.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

[Explanation of symbols]

1 Upper device 2 decoder circuit 4 control circuit 6 Voltage level comparison circuit 7 Lead waveform voltage level 8 Reference voltage level 9 Spindle motor drive circuit 11 Spindle motor

Claims (3)

[Claims] 1. A read waveform voltage level confirmation means for reading a test pattern from a data surface and outputting a read waveform voltage level by a command from a higher-level device, and compares the read waveform voltage level with a predetermined reference voltage level. And a voltage level comparing means for causing the spindle motor used for reading the test pattern to perform a start / stop operation a predetermined number of times when the read waveform voltage level is lower. 2. The magnetic disk device according to claim 1, wherein the test pattern is written in advance in a spare diagnostic cylinder on the data surface. 3. The test waveform is read again by the read waveform voltage level confirmation means after the spindle motor has been started / stopped a predetermined number of times, and the read waveform voltage level obtained by this read again is 2. The magnetic disk device according to claim 1, wherein when the voltage is lower than the reference voltage level, the operation of the spindle motor used for reading the test pattern is stopped and the abnormality is reported to the host device.