JPH02103774A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To prevent data from being destroyed by reading a write signal written in a contact-start-stop (CSS) zone, detecting its signal level, detecting at the same time an abnormality of the read signal and reporting this abnormality to the outside of the device. CONSTITUTION:A magnetic disk 22 is rotated, and the level of the read signal 7 for reading the signal written in advance in the CSS zone 21 of the magnetic disk 22 is detected by varying the level 9 of a reference signal before the rotation becomes under the steady state so as to be the ready state. Then, when this detected value is abnormal, an abnormality display 6 is displayed by a control circuit 1 of a read signal detecting circuit to tell the abnormality, and the magnetic disk device is kept from becoming the ready state as well. By this method, the data written in a data zone 20 can be prevented from being destroyed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic disk device, and particularly to a method for detecting abnormality or damage to a magnetic head or a magnetic disk plate.

[Conventional technology]

In a conventional magnetic disk device that uses a contact start-stop type (CSS type) magnetic head, when the device is stopped, that is, when the magnetic disk plate has stopped rotating, the magnetic The head and the magnetic disk plate are in contact. When the apparatus is started and the magnetic disk plate begins to rotate, the magnetic head slides on the magnetic disk plate until the rotation of the magnetic disk plate reaches a certain rotational speed and the magnetic head floats.

The area on the magnetic disk plate where the magnetic head is located when the magnetic disk plate stops rotating is called the CSS zone, and as shown in Figure 2, there is a data zone 20 where actual data is written. Although the CSS zone 21 is arranged from the outside to the inside of the data zone 20, this figure shows a case where it is arranged inside.

When the rotation of the magnetic disk plate 22 starts and stops, the magnetic head 23 slides on the magnetic disk plate 22 at high speed, so that even if a very small amount of dust adheres to the magnetic disk plate or the magnetic head, the magnetic disk plate, Damage to the magnetic head may occur. When a magnetic disk plate is damaged, it becomes impossible to write data to or read data written to that location.

Therefore, as described above, the C8C zone 21 is arranged separately from the data zone 20.

[Problem to be solved by the invention]

In the above-mentioned conventional magnetic disk drive, the CSS zone on the magnetic disk surface is arranged separately from the data zone, but even if the CSS zone is separated, once even the slightest damage occurs to the magnetic disk in the CSS zone, the damage will occur. If the magnetic disk drive is continued to be used as it is, the data zone will be damaged and it will be impossible to write or read data.

[Means to solve the problem]

In the magnetic disk transport of the present invention, the CS of the magnetic disk is
Read the write signal written in the S zone,
The apparatus includes level detection means for detecting the signal level of the read signal and abnormality reporting means for detecting an abnormality in the read signal and reporting the abnormality to the outside of the apparatus.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 shows a schematic diagram of a read signal detection circuit of a magnetic disk device of the present invention. In FIG. 1, the comparator 3 compares the signal level of the readout signal 7 and the signal level of the reference signal 9 which is the output of the DA converter 2, and the signal level of the readout signal 7 is higher than the signal level of the reference signal 9. When this occurs, a logic signal level II II II is output. The DA converter 2 is a circuit that converts the logic signal from the control circuit 1 into an analog signal proportional to the logic signal. The one-shot circuit 4 detects that the output of the comparator 3 is “1” from II OII at the logic signal level.
1°° at the logic signal level for a certain period of time when it changes to
Output. The time to output this 1'' is set longer than the signal period of the read signal 7. Therefore, when the control circuit 1 specifies the signal level of the reference signal 9 that is lower than the signal level of the read signal 7, the one-shot circuit 4
continues to output the logic signal level "'1'". The counter circuit 5 counts the clock signal 8 while the output of the one-shot circuit 4 is at the logic signal level II II II. This count value and the clock signal 8 The time during which the output of the one-shot circuit 4 is at the logic signal level "'1", that is, the time during which the signal level of the readout signal 7 is higher than the reference signal level 9 specified by the control circuit 1. The counted value of this counter circuit 5 is input to the control circuit 1, and in the control circuit 1, if this counted value indicates 50% of the rotation period of the magnetic disk plate,
It is determined that the signal level of the read signal 7 is equal to the reference signal level 9 designated by the control circuit 1.

Before the magnetic disk device is started and the magnetic disk plate is rotated until the rotation reaches a steady state and the ready state is reached, the readout signal of the signal previously written in the CSS zone of the magnetic disk plate is read out as a reference signal using the method described above. The level of the read signal is detected by changing the level of the read signal.

If there is an abnormality in this detected value, the control circuit 1 of the read signal detection circuit displays the abnormality indicator 6 to notify the abnormality and prevents the magnetic disk device from going into a ready state.

〔Effect of the invention〕

As explained above, the magnetic disk drive of the present invention reads the write signal written in advance in the CSS zone of the magnetic disk, detects the signal level of the read signal by the level detection means, and detects an abnormality in the read signal. By displaying an abnormality in the read signal using the display means or reporting it to the host device using the reporting means, the CS of the magnetic disk board can be detected at the time of contact start/stop.
This has the effect of preventing damage to the magnetic disk plate occurring in the S zone from affecting the data zone and destroying data written in the data zone.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a read signal detection circuit of a magnetic disk drive of the present invention, and FIG. 2 is a layout diagram of a guard band of a magnetic disk plate. ]...Control circuit, 2...DA converter,
3... Comparator, 4... One shot circuit, 5... Counter circuit, 6... Abnormality indicator, 7... Read signal , 8...
Clock signal, 9...Reference signal, 20...
...Dataton, 21...CSS Zone, 2
2...Magnetic disk plate, 23...Magnetic head. Agent Patent Attorney Shinichi Uchihara

Claims (1)

[Claims] In a magnetic disk device in which the magnetic head performs CSS (contact start/stop) operation, a write signal written in advance in the CSS (contact start/stop) zone of the magnetic disk is read out and the signal level of the read signal is detected. A magnetic disk drive comprising: a level detection means; and an abnormality reporting means for reporting an abnormality to an external device when the signal level of the read signal exceeds a preset range.