JPH04286781A - Magnetic recording medium and its forming method and reading voltage inspection method for magnetic recording device - Google Patents

Abstract

PURPOSE:To prevent the occurrence of an unrecoverable data read-out error in advance by finding the occurrence of the defection of respective tracks and the abnormality of a head floating amount of a magnetic disk device for a computer at their early stage. CONSTITUTION:Before the shipment of the device, a value (reference value) obtained by recording a signal at a prescribed frequency in the entire user tracks 28 of a magnetic disk 27 and integrating its reproducing voltage level by the amount of one round of a track for the respective user tracks is grouped and numerically marked in a specific track 29. At the time of utilization, the device independently and automatically reproduces the data in an optional track, integrating reproducing voltage by the amount of one round of the track, comparing the integral value with the reference value for an applicable user track marked on the specific track 29 in the intervals between input/output processings from a host device, and when the difference is beyond a prescribed value, the defection of the disk track is decided.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a method for inspecting read voltages of magnetic recording media such as magnetic disks and magnetic recording devices, and particularly relates to a method for inspecting read voltages of magnetic recording media such as magnetic disks, and in particular, a method for inspecting read voltages of magnetic heads. The present invention relates to a recording medium, a method for making the magnetic recording medium, and a read voltage testing method for a magnetic recording device that uses the magnetic recording medium to detect abnormalities in the read voltage of a magnetic head at an early stage.

0002

[Background Art] Conventionally, in magnetic recording devices such as magnetic disk devices used as storage devices for electronic computers, magnetic recording occurs due to damage and deterioration of the magnetic recording medium, adhesion of dust, or changes in the flying height of the magnetic head or damage. As a method of checking for read failure in the device, for example, as described in Japanese Patent Application Laid-Open No. 2-52832, test program data is recorded on a magnetic disk, read out, and checked for errors in the code of the read data. A common method is a read error check method. In this method, the entire surface of the magnetic disk is inspected by the user writing data to an area of the track that is not normally used, and reading the data code to check for errors.

0003

In the above-mentioned prior art, when a read error occurs due to a change in the magnetic disk medium or a change in the flying height of the magnetic head, and the device becomes unusable, the failure is reported. However, with the above-mentioned method of reading data codes and checking for errors, even if the reproduction voltage level drops to nearly 50% of its normal value, it is often recovered by error correction, and it is difficult to detect changes in the characteristics of the medium or magnetic head levitation. While the change in the amount is still small, it does not become a problem, and it is only when the magnetic head flying height changes considerably that an error occurs that cannot be recovered by normal error correction. It is determined that there is an abnormality and the fact that the failure has occurred is notified, but this will result in data loss and irreversible damage. Therefore, before such a serious failure occurs, it is possible to quickly identify areas where reading failures on magnetic recording media and changes in the flying height of the magnetic head (while the changes are still small) can cause failures. If it can be discovered, it is convenient because it can prevent serious problems that may occur later.

Furthermore, in the above-mentioned conventional technology, after the magnetic disk device is shipped and installed at the user's location, the inspection is carried out at the user's request based on a command from the host device. In order to perform the inspection on all tracks, it is necessary to interrupt the inspection work in addition to the normal data input/output work, which requires work time. Therefore, it would be convenient if such inspections were to be performed automatically between normal data input/output operations, since system users would not have to consciously interrupt such inspections. be.

Therefore, an object of the present invention is to measure and monitor the read voltage of the magnetic recording medium for the entire track area of the magnetic recording medium, thereby detecting changes in the characteristics of the medium and the flying height of the magnetic head. To provide a magnetic recording medium, a method for producing the same, and a method for inspecting read voltage of a magnetic recording device, in which the occurrence of data read errors during normal use can be detected at an early stage, thereby preventing the occurrence of data read errors. It is in.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the magnetic recording medium of the present invention provides a magnetic recording medium with a normal state measured for each track (including all cylinders) in the recording area of the magnetic recording medium. A specific track is provided in which the amplitude value (reference value) of the read voltage is written.

The method for producing this magnetic recording medium is as follows. First, a signal with a constant frequency and a constant amplitude is recorded on all user tracks in the recording area of a magnetic recording medium. Next, this is reproduced (read out) for each track, and the read voltage is integrated over one revolution of the track, and this integrated value is taken as the magnitude (reference value) of the read voltage in the normal state of the track. In this way, the reference value for all user tracks is measured for each track, and the obtained reference value for all the tracks is written as data to a specific track of this magnetic recording medium. The above magnetic recording medium is created before the system (magnetic recording device) is shipped.

The reading voltage testing method for a magnetic recording device using this magnetic recording medium is carried out by the user as follows after the system (magnetic recording device) is shipped. Normal use from the central processing unit CPU (upper device) (
When no input/output processing is being performed, the magnetic recording device arbitrarily selects an appropriate cylinder (track) or magnetic head of the magnetic recording medium, reads the data recorded there, and adjusts the read voltage of this data. The amplitude is measured, and this measured value is compared with the reference value data of the corresponding track written in the specific track of this magnetic recording medium, and based on the comparison result, it is possible to determine whether there is an abnormality in the magnetic recording medium or whether the magnetic head is floating. The presence or absence of an abnormality in the amount is determined and the content of the determination is notified.

[0009]

[Operation] The operation based on the above configuration will be explained.

When producing the above magnetic recording medium, a signal of a certain frequency and a predetermined amplitude is recorded on all tracks (cylinders) of the recording area of a normal magnetic recording medium before shipment, and this is reproduced to determine the reproduction voltage. is integrated for each track round, and
The integrated value is used as the normal read voltage (reference value) for that track, and the reference values of all the tracks are collectively written as data to a specific track on this magnetic recording medium.

Next, after shipping, the user side measures the read voltage of the magnetic head to detect abnormalities in the magnetic recording medium and the flying height of the magnetic head. In this case, when there is no normal use (input/output processing) from the CPU (upper device),
A magnetic recording device automatically and randomly selects a track (cylinder) or magnetic head without receiving a command from a host device, reads out the data recorded there, and applies the read voltage to one cycle of the track. Integrate the parts,
Measure the integral value and compare the measurement result with the reference value of the corresponding (same) track. If a defect occurs in the corresponding track of the magnetic recording medium, the integrated value of the current data read voltage will change by the amount of the defect, resulting in a difference in the comparison results, and it will be possible to detect abnormalities in the magnetic recording medium at an early stage. can be detected. In order to strictly detect this abnormal state and discover it as early as possible, the detection level of the difference in the measured value compared to the reference value (normal value) should be reduced, for example, by 5 to 10% compared to the reference value. Alternatively, a medium abnormality can be determined when the read voltage changes by about 20%. Considering changes in the flying height of the magnetic head as well, the reading voltage may not only decrease but also increase compared to the reference value, so generally the positive and negative abnormality detection levels are set (for example, ±5 to 10%). ). Note that when checking for abnormal conditions, the track is read based on the data written there, but the read voltage level difference due to the difference in frequency with the signal written before shipping must be corrected (calibrated) in advance. put.

In this way, when the magnetic recording medium begins to deteriorate due to damage or the flying height of the magnetic head begins to change, the resulting change in the reading voltage of the magnetic head is detected, and the magnetic recording medium is It is possible to detect damage etc. at an early stage, and prevent irrecoverable read errors and irreversible system (magnetic recording device) failures.

[0013]

[Embodiments] Hereinafter, embodiments of the present invention will be explained with reference to the drawings.

FIG. 4 shows, as applied to one embodiment of the present invention,
FIG. 2 is a configuration diagram of a circuit that also serves as a circuit for creating a magnetic recording medium and a read voltage measurement and comparison circuit. In Figure 4, 10
is a magnetic disk, 11 is a magnetic head, 12 is an amplifier, 1
3 is a waveform equalization circuit, 14 is a data creation circuit, 15 is an envelope circuit, 16 is an integration circuit, and 17 is an amplitude comparison circuit.

FIGS. 1 to 3 and 6 are waveform diagrams at various parts of FIG. 4. Further, FIG. 7 is a configuration diagram of a magnetic disk created by applying this embodiment.

First, before shipping, the head 1 shown in FIG.
1. A magnetic disk as shown in FIG. 7 is created from a portion including circuits 12, 13, 15, and 16. For this purpose, the head 11 and a recording circuit (not shown) record a sinusoidal waveform signal of constant frequency and constant amplitude shown at 24 in FIG. 6 on all tracks (cylinders) 28 of the recording area of the target magnetic disk 27. This recorded constant frequency signal is then
The signal is reproduced by the head 11, amplified by the amplifier 12, passed through the waveform equalization circuit 13, full-wave rectified (waveform 25) and peak sensed (waveform 26) by the envelope circuit 15, and then integrated for each track by the integration circuit 16. be done. The integrated voltage level for each track is measured by a voltage measurement circuit (not shown), and the measured value is displayed as data (numeric value) on the specific track 29 (FIG. 7) along with track instruction information for each track. are written together. In this way, a magnetic disk 27 shown in FIG. 7 is obtained. In addition, area 28
The constant frequency signal recorded on the device can be erased or left as required before shipping.

Next, the operations performed on the user side after shipping will be explained.

As described above, this operation is not performed when the host device is activated at the user's request, but is performed independently and arbitrarily when input/output processing from the host device is not being performed. The signal (data) read by the magnetic head 11 from the track 28 in the user area of the magnetic disk 10 (27 in FIG. 6) is amplified by the amplifier 12 and supplied to the waveform equalization circuit 13, where the write frequency is adjusted. The signal amplitude, which varies with Further, a signal with a resolution of 100% with no amplitude change due to the pattern is created by the data creation circuit 14, and this is transferred as data to the host CPU for normal data processing. On the other hand, the output signal of the waveform equalization circuit 13 is processed by the envelope circuit 15 in the same manner as in the case of FIG. The read voltage value for one round of (27) is output. The initial signal amplitude value (numerical value) written in the specific cylinder 29 at the time of shipment is read out as data, and the amplitude comparison circuit 17 compares it with the read voltage value. Perform monitoring.

FIG. 1 shows a normal readout signal 1, a signal 2 which is an integral of this signal, and a signal amplitude voltage value 3 integrated for one cycle (from index to next index detection).
shows. FIG. 2 shows a read signal 4, an integrated signal 5, and an amplitude voltage value 6 integrated over one cycle when a defect occurs on the disk 10. Due to the defective portion 18, the signal being integrated has an integral amount of 0 when the signal is defective, so the amplitude voltage value 6 becomes smaller than the amplitude voltage value 3 in the normal state. This indicates that an abnormality has occurred in the relevant cylinder. FIG. 3 shows the readout signal 7, the integrated signal 8, and the amplitude voltage value 9 integrated over one round when the flying height of the head decreases. When the flying height of the head decreases, the read amplitude value becomes larger than in the normal state, and therefore the amount of integration also increases, and the amplitude voltage value 9 becomes larger than in the normal state. This result indicates that an abnormality has occurred in the target magnetic head. The abnormality occurrence signals detected in FIGS. 2 and 3 are transferred to the CPU, prompting the operator to request intervention at an early stage, and preventing read errors from occurring.

Next, in FIG. 5, the envelope circuit 1 of FIG.
5 and an example of a specific circuit configuration of the integrating circuit 16. Further, the operation contents of the envelope circuit are shown in FIG. The waveform 24 input to the envelope circuit is transmitted to the transistor 19
full-wave rectification by From the full-wave rectified waveform 25, a diode 20 and a capacitor 21 create a waveform consisting only of the peak point of the waveform, that is, an envelope waveform 26. The operational amplifier 22 is used as a voltage follower. The envelope waveform created in the above manner is processed using a commonly known integrating circuit.
Integrate over one revolution of the disk to create an amplitude voltage value. Analog switch 23 is used to reset the integrating circuit.

FIG. 7 shows a cylinder whose amplitude voltage value is measured in this embodiment and a cylinder whose initial value at the time of shipment is kept as data. Disc 27, head 30 (
The initial amplitude value of the cylinder 28 used by the user is written in the cylinder 29 using the head 11 (also used as the head 11 in FIG. 4). The cylinder 29 was set as the innermost cylinder of the disc, and was a cylinder that the user was prohibited from using. By the above method, it is possible to inspect and monitor the damage and deterioration of the disk medium and the flying height of the head.

[0022] Furthermore, the readout voltages of all cylinders are periodically measured and the amplitude voltage value of the readout voltage is additionally updated, and this additionally updated voltage value is specified together with the reference value (initial value). By writing in the cylinder 29, it is also possible to check the evidence (history) of amplitude changes.

[0023]

[Effects of the Invention] As explained in detail above, according to the present invention, the normal reading voltage level (amplitude) is measured for each track in advance for all tracks in the recording area of a magnetic recording medium before shipping the system. The measured value is written as reference value data on a specific track of the magnetic recording medium, and after shipping, the level (amplitude) of the read voltage from any track is randomly compared with the reference value, and based on the comparison result. By determining whether there is an abnormality in the magnetic recording medium or magnetic head floating in the magnetic recording device, it is possible to detect the abnormality at an early stage and prevent failures such as irrecoverable read errors from occurring in the magnetic recording device. This has the effect of making it possible to prevent this.

[0024] Furthermore, the measurement of the read voltage of data, etc. by the magnetic head is not performed by a command from a higher-level device, but by the magnetic recording device's own judgment, randomly selecting a vacant input/output processing area for an arbitrary track. Since the measurement is carried out at regular intervals, it is possible to automatically perform measurements at an early stage and detect abnormal conditions without the user having to issue a request one by one.

[Brief explanation of the drawing]

FIG. 1 is a waveform diagram of a read signal and an integral waveform during normal operation according to an embodiment of the present invention.

FIG. 2 is a waveform diagram of a read signal and an integral waveform when a disk defect occurs according to an embodiment of the present invention.

FIG. 3 is a waveform diagram of a read signal and an integral waveform when the flying height of the head decreases.

FIG. 4 is a circuit configuration diagram of a signal amplitude monitoring method applied to an embodiment of the present invention.

FIG. 5 is a circuit diagram of an envelope circuit and an integration circuit in FIG. 4;

FIG. 6 is an operational waveform diagram of the envelope circuit.

FIG. 7 is a configuration diagram of a magnetic disk according to an embodiment of the present invention.

[Explanation of symbols]

1 Read signal at normal time 2 Integral waveform at normal time 3 Signal amplitude voltage value at normal time 4 Read signal at time of disk defect occurrence 5 Integral waveform at time of disk defect occurrence 6 Signal amplitude voltage value at time of disk defect occurrence 7 Head flying height Readout signal when the head flying height decreases 8 Integral waveform when the head flying height decreases 9 Signal amplitude voltage value when the head flying height decreases 10, 27
Disks 11, 30 Magnetic head 12 Amplifier 13 Waveform equalization circuit 14 Data creation circuit 15 Envelope circuit 16 Integration circuit 17 Amplitude comparison circuit 18 Disk defect 19 Full-wave rectification transistor 20 Waveform peak sensing diode 21 Waveform peak sensing capacitor 22 operational amplifier 23 for voltage follower analog switch 24 for resetting the integration circuit input waveform 25 of envelope circuit waveform 26 full-wave rectified by envelope circuit
Waveform 28 peak-sensed by envelope circuit
Cylinder used by the user 29 Cylinder in which the signal amplitude value is written at the time of shipment of the device

Claims (3)

[Claims] 1. A magnetic recording medium characterized in that, for all user tracks in a recording area, a specific track is provided in which the amplitude of a read voltage in a normal state measured for each track is written as a reference value. 2. A step of recording a signal of a constant frequency on all user tracks in a recording area of the magnetic recording medium, and a step of reading out the recorded signal and integrating the read voltage for each track revolution. 2. The method for producing a magnetic recording medium according to claim 1, further comprising the step of writing the integrated value on a specific track of the magnetic recording medium as a reference value. 3. A step of arbitrarily selecting a user track and a magnetic head, reading a recording signal, and integrating the read voltage for each track when input/output processing from a host device is not being performed, and the integrated value thereof. 2. The method of claim 1, further comprising the step of comparing the voltage with a reference value related to the corresponding user track written in the specific track, and the step of determining whether there is an abnormality in the read voltage of the user track based on the comparison result. 1. A read voltage testing method for a magnetic recording device using the magnetic recording medium according to 1.