JPH05325119A - Magnetic disc unit - Google Patents

Abstract

PURPOSE:To take countermeasure against trouble of inclined spindle due to abrasion of bearing by interrupting transmission of signal to a disc processing unit when the level of read out signal drops below a predetermined level being set through a level setting circuit. CONSTITUTION:A data head 16-1-16-n is selected through a magnetic head selecting circuit 3 in a magnetic disc unit 12 and a signal read out from a magnetic disc 20 is delivered through a data amplifier 4 to a comparing circuit 10, where the signal is subjected to comparison with a level being set by a level setting circuit 9. The voltage level is set between a read out level for normal operation and a substantially undetectible low level corresponding to inclination of disc spindle due to abrasion of bearing. When the read out level drops below the set level, transmission of signal to a magnetic disc processor 13 is interrupted through a majority circuit 11 and the like, thus taking countermeasures against trouble of inclined spindle.

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 having a plurality of magnetic disks and a plurality of corresponding data heads.

[0002]

2. Description of the Related Art FIG. 3 is a block diagram showing an example of a conventional magnetic disk device, FIG. 4 is a front view showing details of a head disk assembly of the example of FIG. 3, and FIG. 5 is a data amplifier of the example of FIG. FIG. 6 is a waveform diagram showing the waveform of the output signal, and FIG. 6 is a format diagram showing the track format written on the magnetic disk of the example of FIG.

As shown in FIG. 3, a conventional magnetic disk device 42 for a computer system includes a plurality of magnetic disks 20 and a plurality of data heads 16-1 provided corresponding to the magnetic disks 20 for writing and reading information. .About.16-n, a head disk assembly 1 including a servo head 2 for reading an index signal from the magnetic disk 20, a servo amplifier 25 for amplifying a read signal from the servo head 2,
An index detection circuit 28 that detects an index signal from the output signal of the servo amplifier 25, a magnetic head selection circuit 23 that selects one of the plurality of data heads 16-1 to 16-n, and a magnetic head selection circuit. A data amplifier 24 that amplifies the output signal of the data head selected by 23, a home address detection circuit 27 that detects a home address from the output signal of the data amplifier 24 at the detection timing of the index signal, and an output signal of the data amplifier 24. And a data control circuit 26 for converting into a data signal.

As shown in FIG. 4, the head disk assembly 1 includes a spindle 36, ball bearings 37 and 38 for supporting the spindle 36 at its upper and lower portions, a magnetic disk 20 mounted on the spindle 36, and a spindle 36. It has a motor 39 for rotating, a servo head 2 for reading an index signal from the magnetic disk 20, and a plurality of data heads 16-1 to 16-n for writing / reading information (data) to / from the magnetic disk 20. ing.

As shown in FIG. 5, the data amplifier read signal 34 output from the data amplifier 24 indicates the signal voltage V when the data is read normally, and the signal voltage V when the data is read abnormally. The voltage Ve is shown.

The magnetic disk 20 is formatted in the track format shown in FIG. That is, the magnetic disk 20 is shipped with the home address 54 and the records 55-1 to 55-n formatted in the factory.

Next, the operation of the magnetic disk device configured as described above will be described.

When reading data from the magnetic disk 20, first, the magnetic head selection circuit 23 selects only one target data head from the data heads 16-1 to 16-n. The signal read by the selected data head is amplified by the data amplifier 24. The signal amplified by the data amplifier 24 is sent to the data control circuit 26. The signal sent to the data control circuit 26 includes a home address 54 and a record 55-
1-55-n are included and their separation is necessary. Home address 54 and records 55-1 to 5-5
To separate 5-n from home address detection circuit 27
At, the home address is detected by the signal from the index detection circuit 28.

The ball bearings 37 and 38 of the head disk assembly 1 are worn by a long use, and when the ball bearings 37 and 38 are worn, the spindle 36 is tilted. When the spindle 36 gradually tilts due to long-term use, the data amplifier read signal 34 gradually decreases from the signal voltage V in the normal state to the signal voltage Ve in the abnormal state.

[0010]

As described above, in the conventional magnetic disk device, it is impossible to avoid the inclination of the spindle because the ball bearings are worn out due to long-term use. When the inclination of the spindle exceeds a certain value, the signal voltage of the data amplifier read signal becomes equal to or less than the limit value, so that the conventional magnetic disk device has a drawback in that the data cannot be read and a read failure occurs. Have

[0011]

A magnetic disk apparatus according to the present invention comprises a spindle for rotating motion, a plurality of magnetic disks mounted on the spindle, a servo head for reading an index signal from the magnetic disk, and A servo amplifier that amplifies a read signal of the servo head, an index detection circuit that detects an index signal from the output signal of the servo amplifier, and a write / read of information to / from a corresponding magnetic disk of the plurality of magnetic disks. A plurality of data heads to be performed, a magnetic head selection circuit for selecting one of the plurality of data heads, and a data amplifier for amplifying an output signal of the data head selected by the magnetic head selection circuit. The output signal voltage value from the data amplifier in advance. A level setting circuit set to an intermediate voltage value between a voltage value in a normal case and a voltage value in a case where an output signal from the data amplifier is a fault, and a voltage value of the output signal from the data amplifier and the level setting A comparison circuit that compares the voltage value of the output signal from the circuit at the detection timing of the index signal, and an output signal of the comparison circuit that is designated by a signal from the magnetic head selection circuit of a plurality of storage circuits. The circuit is provided with a storage circuit group for storing in the circuit and a majority circuit operated by a plurality of signals from the storage circuit group.

[0012]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a waveform diagram showing a waveform of an output signal of the level setting circuit of the embodiment of FIG.

The magnetic disk device 12 of FIG. 1 includes a plurality of magnetic disks 20 and a plurality of data heads 16-1 to 16- provided corresponding to the magnetic disks 20 for writing and reading information.
n and a servo head 2 for reading an index signal from the magnetic disk 20.
A servo amplifier 5 that amplifies a read signal of the servo head 2, an index detection circuit 8 that detects an index signal from an output signal of the servo amplifier 5, and one of a plurality of data heads 16-1 to 16-n. A magnetic head selection circuit 3 that selects a data head, a data amplifier 4 that amplifies the output signal of the data head selected by the magnetic head selection circuit 3, and an index signal from the data amplifier read signal 14 of the output signal of the data amplifier 4 A home address detection circuit 7 for detecting a home address at the detection timing, and a data control circuit 6 for converting the data amplifier read signal 14 into a data signal are further provided.
A level setting circuit 9 in which the voltage value of the output signal is set to an intermediate voltage value between the voltage value when the data amplifier read signal 14 is normal and the voltage value when the data amplifier read signal 14 becomes an obstacle, and the data amplifier read A comparison circuit 10 for comparing the voltage value of the signal 14 and the voltage value of the level setting circuit read signal 15 of the output signal of the level setting circuit 9 at the detection timing of the index signal, and the output signal of the comparison circuit 10 from the magnetic head selection circuit 3. The plurality of storage circuits 17-1 to 17-n for storing in a location designated by the signal and the majority circuit 11 operated by the plurality of signals from the storage circuits 17-1 to 17-n.

The magnetic disk device having the above structure is
As shown in FIG. 2, the signal voltage Va of the level setting circuit read signal 15 is set in advance to the data amplifier read signal 1
4 is set to an intermediate voltage value between the signal voltage V (see FIG. 5) when it is normal and the signal voltage Ve (see FIG. 5) when the data amplifier read signal 14 becomes an obstacle.

When data is read from the magnetic disk 20, the target data head is first selected from the data heads 16-1 to 16-n by the magnetic head selection circuit 3 as in the conventional example shown in FIG. Select only one. The signal read by the selected data head is amplified by the data amplifier 4. The data amplifier read signal 14 amplified by the data amplifier 4 is sent to the data control circuit 6. The signal sent to the data control circuit 6 includes
As described above, the home address 54 (see FIG. 6) and the records 55-1 to 55-n (see FIG. 6) are included. Home address 54 and records 55-1 to 55-n
The home address detection circuit 27 detects the home address based on the signal from the index detection circuit 8.

At this time, there is no problem when the voltage value of the data amplifier read signal 14 sent at the detection timing of the index signal is the signal voltage V in the normal case, but it is less than the signal voltage Ve due to the inclination of the spindle. If this happens, the data cannot be read, and a read failure occurs.

The data amplifier read signal 1 due to the tilting of the spindle is used to give a warning before a read is no longer possible.
It is confirmed that the range of decrease in the voltage value of 4 is equal to or higher than the signal voltage Va of the level setting circuit read signal 15 shown in FIG. Therefore, the voltage value of the data amplifier read signal 14 and the signal voltage Va of the level setting circuit read signal 15 are compared in the comparison circuit 10.

When the voltage value of the data amplifier read signal 14 is larger than the signal voltage Va of the level setting circuit read signal 15, there is no problem. Data amplifier read signal 1
4 is smaller than the signal voltage Va of the level setting circuit read signal 15, the signal from the comparison circuit 10 is stored in the storage circuit 17-1 to 17-n designated by the magnetic head selection circuit 3. Accumulate in the circuit. Storage circuit 1
Comparing circuit 1 is provided in a plurality of storage circuits 7-1 to 17-n.
When the signal from 0 is accumulated, it indicates that the voltage value of the read signal from the plurality of data heads is lower than the reference value. Therefore, the majority circuit 11 is operated to output the output signal from the magnetic disk. It is sent to the processing device 13 to notify that the spindle is tilted.

[0020]

As described above, the magnetic disk device of the present invention is provided with the level setting circuit in which the voltage value of the output signal is set to a predetermined value in advance, and the data amplifier read signal and the level setting circuit read signal are provided. In comparison, when the voltage value of the read signal from the plurality of data heads becomes lower than the voltage value of the level setting circuit read signal, the signal is sent to the magnetic disk processing device, so that the bearing The spindle tilts due to wear,
There is an effect that it is possible to detect that the signal voltage has dropped before the signal voltage of the data amplifier read signal becomes less than the limit value and data cannot be read. Therefore, a measure is taken before a read failure occurs. Therefore, there is an effect that a highly reliable magnetic disk device can be obtained.

[Brief description of drawings]

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

FIG. 2 is a waveform diagram showing a waveform of an output signal of the level setting circuit of the embodiment of FIG.

FIG. 3 is a block diagram showing an example of a conventional magnetic disk device.

FIG. 4 is a front view showing details of the head disk assembly of the example of FIG.

5 is a waveform diagram showing a waveform of an output signal of the data amplifier of the example of FIG.

FIG. 6 is a format diagram showing a sector format written in the magnetic disk of the example of FIG.

[Explanation of symbols]

 1 head disk assembly 2 servo head 3.23 magnetic head selection circuit 4.224 data amplifier 5.25 servo amplifier 6.26 data control circuit 7.27 home address detection circuit 8.28 index detection circuit 9 level setting circuit 10 comparison Circuit 11 Majority decision circuit 12/42 Magnetic disk device 13 Magnetic disk processing device 14 Data amplifier read signal 15 Level setting circuit read signal 16-1 to 16-n Data head 17-1 to 17-n Storage circuit 20 Magnetic disk 36 Spindle 37・ 38 ball bearing 39 motor 54 home address 55-1 to 55-n record

Claims (2)

[Claims] 1. A spindle for rotating motion, a plurality of magnetic disks mounted on the spindle, and a plurality of data for writing / reading information to / from a corresponding magnetic disk of the plurality of magnetic disks. A head, a magnetic head selection circuit for selecting one of the plurality of data heads, a data amplifier for amplifying an output signal of the data head selected by the magnetic head selection circuit, and an output signal A level setting circuit that sets a voltage value in advance to an intermediate voltage value between the voltage value when the output signal from the data amplifier is normal and the voltage value when the output signal from the data amplifier causes an obstacle,
A comparison circuit for comparing the voltage value of the output signal from the data amplifier with the voltage value of the output signal from the level setting circuit, and the output signal of the comparison circuit from the magnetic head selection circuit of the plurality of storage circuits. And a majority circuit that operates by a plurality of signals from the storage circuit group. 2. A spindle for rotating motion, a plurality of magnetic disks mounted on the spindle, and a servo head for reading an index signal from the magnetic disk.
A servo amplifier that amplifies a read signal of the servo head, an index detection circuit that detects an index signal from an output signal of the servo amplifier, and a writing / reading of information to / from a corresponding magnetic disk of the plurality of magnetic disks. A plurality of data heads, a magnetic head selection circuit for selecting one of the plurality of data heads, and data for amplifying an output signal of the data head selected by the magnetic head selection circuit. An amplifier and a level in which the voltage value of the output signal is set in advance to an intermediate voltage value between the voltage value when the output signal from the data amplifier is normal and the voltage value when the output signal from the data amplifier becomes an obstacle. Setting circuit, voltage value of output signal from the data amplifier and output signal from the level setting circuit A comparison circuit that compares voltage values at the detection timing of the index signal, and a storage circuit that stores the output signal of the comparison circuit in a storage circuit designated by a signal from the magnetic head selection circuit among a plurality of storage circuits. Group, and a majority circuit that operates according to a plurality of signals from the storage circuit group.