JPH103624A - Magnetic recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten a processing time of head clogging measures by providing an output level history observing device observing history of numerical values of reproduction output levels of a recording head and a reproducing head converted by a converter. SOLUTION: A tracking shift detecting envelope signal is used for generating a tracking control signal in a tracking error detection circuit 10, and an RF envelope signal is A/D converted 9 to be used for generating the output level numerical value data from a reproduced signal. Then, the history of the numerical values of respective reproduction output levels of the recording head 1 and the reproducing head 2 are observed by a tracking error detection circuit 10 and a servo control CPU 11. Thus, since the accurate state of the head clogging and its history are grasped, the head clogging measures can be taken in an earlier stage before error processing by a parity code, etc., after a signal is processed at a recording time and a reproducing time also, and the processing time for the clogging measures is shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a magnetic recording apparatus, and more particularly to an improvement in a method for coping with a clogging phenomenon caused by dust or the like in a magnetic recording apparatus in which magnetic recording is performed by helical scanning.

[0002]

2. Description of the Related Art In a conventional magnetic recording apparatus in which magnetic recording is performed by helical scanning, in order to achieve high-density recording, a track and a gap are becoming narrower in recent years. For this reason, even a slight spacing generated between the head and the tape causes a reduction in the reproduction level, and a slight dust or dust adhering to the head or the tape also poses a problem. Such a phenomenon that no output is produced due to the spacing generated between the head and the tape due to the attachment of dust or the like to the head or the tape is called head clogging. Since such a head clogging phenomenon occurs suddenly, usually, in order to prevent this, the tape traveling system including the head is cleaned with a cleaning tape or the like before the tape traveling time exceeds a certain accumulated time. The equipment is being maintained.

[0003] However, such periodic cleaning involves an inconvenience in that the system requires an apparatus stoppage time correspondingly, and the cleaning tape increases wear on the head. Further, since such a cleaning method is not a complete preventive measure, if it occurs at the time of recording and reproduction, the recording and reproduction are performed again, that is, a retry operation is performed. Such a retry operation is normally performed automatically in a tape device for a computer, so that the operator does not need to pay special attention, but the cause is not specified, and in the worst case, The device itself stops abnormally and is left unattended. In this case, although it can be saved by performing the head cleaning again, it is performed as a process outside the regular management.

[0004] When retry occurs due to head clocking during recording, and recording is executed with the recording position shifted without causing a tape failure, if the recording is executed with slight clocking,
In spite of the fact that the attached debris is naturally removed during the retry, the retry is normally completed and the tape is wasted. As described above, in the range of the related art, since the cause of the defect in the reproduced signal is unclear, there is a problem that the countermeasure processing is delayed or a recording tape or time is wasted.

[0005]

As described above, the conventional countermeasure against head clogging has been only periodic head cleaning or retry operation. Therefore, the countermeasure processing is delayed without clearing the cause of the trouble, or the recording tape or time is not used. In some cases, there is a problem that the device itself is wasted, and in the worst case, the device itself stops abnormally.

The present invention solves this problem, and implements a countermeasure against head clocking at an early stage before error processing by a parity code or the like after signal processing at the time of recording and reproduction. It is an object of the present invention to realize a magnetic recording apparatus capable of shortening the processing time of the countermeasure, preventing a stop processing of the apparatus itself, and preventing an invalid record from remaining.

[0007]

In order to achieve the above object, the present invention has a plurality of recording heads and reproducing heads, and performs recording and reproduction on a magnetic recording medium by helical scanning the recording head and reproducing head. In the magnetic recording apparatus, conversion means for numerically converting a reproduction output level of a reproduction signal obtained by reproducing a signal recorded on the magnetic recording medium using the plurality of recording heads using each of the recording head and the reproduction head, Output level history observing means for observing the history of the numerical value of the reproduction output level of each of the recording head and the reproducing head converted by the conversion means.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A helical scan type magnetic recording apparatus according to the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a block diagram of a helical scan type magnetic recording apparatus according to the present invention. In FIG. 1, 1 is a recording head, 2 is a reproducing head, 3 is a head changeover switch,
4 is a preamplifier, 5 is a rotary transformer, 6 is an equalizer, 7 is a recording control device, 8 is an RF envelope detection circuit, 9 is an A / D converter, 10 is a tracking error detection circuit, 11 is a system control and servo control CPU,
12 is a head cleaner, 13 is a drive amplifier, 14 is C
TL amplifier, 15 is a control motor, 16 is a CTL head,
17 is an erasing head, 18 is a processing block, and 19 is a display.

Next, the operation of this device will be described. At the time of recording, for example, a signal recorded on a recording medium (not shown) by the A-channel recording head 1-a is immediately reproduced by the A-channel reproducing head 2-a. The signal recorded by the A-channel recording head 1-a can be reproduced by the A-channel recording head 1-a itself by switching the head changeover switch 3. This makes it easy to determine whether the defect such as clog is on the recording head 1 side or the reproducing head 2 side. These reproduction signals are all sent to the reproduction side preamplifier 4-1 via the channel changeover switch 3 and input to the equalizer 6 via the reproduction side rotary transformer 5-1. FIG. 1 shows only the portion up to this point for the A channel, but similar circuits are actually prepared for the other channels.

In the equalizer 6, the reproduced signal is divided,
One is sent to the processing block 18 and the other is sent to the RF envelope detection circuit 8 for creating (detecting) the envelope of the reproduced signal. The RF envelope detection circuit 8 derives the tracking error detection envelope signal (Tracking Error Detect Envelope Signal) and the RF envelope signal (Radio-Frequency Envelope Signal) from this signal.
And output.

Among these signals, the envelope signal for tracking deviation detection is a tracking control signal (Tracking Control Signal) in the tracking error detection circuit 10.
nal), and the RF envelope signal is A /
The D / A converter 9 performs A / D conversion to generate output level numerical data from a reproduced signal. The tracking control signal and the output level numerical data are sent to the system control and servo control CPU 11.

FIG. 2 shows a SAT (Signal AutoTracking) track format of the helical scan type magnetic recording apparatus of the present invention. In this track format, adjacent channels are recorded at different azimuth angles as can be seen in FIG. 2, and a pilot signal (SAT PILOT High Frequency) inserted between each recording area is affected by crosstalk of the adjacent channel. In consideration of this, the pilot signal is a signal of a single frequency (for example, 5.25 MHz) that stabilizes the reproduction envelope, and this pilot signal is recorded at a timing different from that of the adjacent channel. At the head of each recording area, a preamble signal for distinguishing sectors is recorded. Since the signal considered in this way is a signal that is constantly monitored for the need of tracking, it has conditions effective for observing the reproduction output from the reproduction head 2.

Next, a method of detecting the level of a reproduced signal using this signal will be described. The detection of the RF level of the reproduction signal is performed, for example, by detecting the RF signal reproduced by the recording head (FIG.
This is performed by obtaining the RF envelope (FIG. 3C) from (a)) and detecting the envelope level of the pilot signal in the RF envelope. This level detection is performed during the timing pulse (FIG. 3B). After the no-signal area of each channel, the system control and servo control CPU 11 selects a timing from a preamble signal for synchronization provided at the head of the signal area.
It consists of. The actual level detection is performed by system control and servo control CP of the magnetic recording apparatus as shown in FIG.
The state of the recording medium is controlled by U11 to STOP-PLAY.
-Change to Servo lock and change to Servo
The level (V1) is detected at a timing (T1) after entering the ock state.

Here, Serv after the device starts operating
S performed by the tracking error detection circuit 10 and the system control and servo control CPU 11 up to o-lock.
The AT operation will be briefly described. The device stops (STO
During P), the SAT operation is in a standby state. When the device enters the PLAY and starts moving, CTL (longitudinal control)
Lock for the CTL signal recorded on the track
Tracking is performed based on (CTL lock) and the X length correction related to the time position of the timing pulse described above. This time is the time required for the rotational speeds of the plurality of control motors of the apparatus to enter a steady state. During this time, the detected RF level is low because the tape running speed is lower than the steady state.

After a certain period of time, the tape running speed becomes a steady speed. Entering the steady state means that CTL lo
In the state of ck, the RF level is detected and the determination is made based on the RF level. Once in steady state, tracking is CTL
Move from lock to Servo lock. Serv
In the o-lock, the tracking is constantly changed little by little, the RF level is monitored, and tracking is performed by a so-called “hill-climbing operation” in which tracking is performed at a position where a peak of the RF level can be captured. Therefore, RF level detection must always be performed for tracking, and it is convenient if this RF level detection can also be used for head clocking determination.

Next, a method of the head clocking judgment processing will be described. FIG. 4 is a schematic flowchart of the head clocking determination process. When the process starts,
First, the following initial values are set (step 10).
1). a) the number of level data samplings (here, the number of samples within the timing pulse period); b) reference level data; c) data representing the number of times the reference level has passed (relative to the number of samples).

After the initial setting, level data is sampled, and the following processing is executed (step 102). a) reading sampling data,
b) comparison of sampling data with reference level data,
c) Counting the number of samples that passed the reference level, etc.

Thereafter, the following judgment contents are judged from these results (step 103). a) indicating a level higher than the reference level (passed)
B) comparing the number of samples with the number of passes of the reference level, b) determining continuity from the previous sampling result. When the results of these head clogging determination processes are obtained, the channel number of the head and the recording head
The next processing block (Signal
Processor / Memory Control / SCSI-Format Control).

In the next processing block, if it is determined that a head clog has occurred according to the determination result, the following processing is appropriately performed as a countermeasure processing. a) Activate the head cleaner, b) Execute retry of recording and reproduction, c) Request cleaning (display on the display, execute by command from SCSI bus). Then, when the cleaning tape is injected, the cleaning traveling is automatically performed.

Next, after such a countermeasure process is executed, the same determination process as described above is performed again to confirm the effect of the countermeasure process. If a clogging error still occurs as a result of this check, the log data is processed as an error due to another cause, and a series of countermeasure processing systems are completed.

Further, even during normal recording or reproduction after tracking, the above-described processing is made to function as a head clog monitor and combined with an error correction processing function, so that the cause when error correction cannot be performed is clearly defined. Become. This makes it possible to clarify that there is no problem such as damage to the tape without wasting a long tape section as an invalid recording section in a retry, especially in recording, so that retry of recording at the same position can be performed again, thereby improving efficiency. It is a target.

As described above, in a helical scan magnetic recording apparatus, the higher the recording density, the more important the tracking becomes, and some kind of tracking signal is required on the track format. This tracking signal is used as a head clog monitor signal because the tracking signal used for this tracking and the signal required to accurately determine the clog of the head match in that the output level is stable. In the present invention, a pilot signal as a tracking signal is used as a head clog monitor signal.

In this case, since the tracking signal is used for the tracking servo which always enters the recording or reproduction mode, the head clog monitor always checks first and enters the recording or reproduction mode. For this reason, error recording by the head clog is started early without performing invalid recording or reproduction.

According to this method, the accurate state of the head clog (for example, which head is the target, how much the level has been reduced, the history thereof, etc.) can be grasped, and various head clog countermeasures (head cleaner, cleaning, etc.) Tape, etc.). Therefore, appropriate measures can be taken without taking unnecessary error measures, and can be dealt with in the shortest measure time.

Although the above method can be effectively used for a digital data recording apparatus, it is not particularly related to a recording method. Therefore, if an analog recording apparatus has a signal area corresponding to a tracking signal, it can be applied without any problem.

[0026]

As described above, according to the first aspect of the present invention, a plurality of recording heads and a plurality of reproducing heads are provided.
In a magnetic recording apparatus for performing recording and reproduction on a magnetic recording medium by helically scanning the recording head and the reproduction head, a signal recorded on the magnetic recording medium using a plurality of recording heads is reproduced using each of the recording head and the reproduction head. Converting means for numerically converting the reproduced output level of the reproduced signal, and output level history observing means for observing the history of the numerical values of the reproduced output levels of the recording head and the reproducing head converted by the converting means. And As a result, the accurate state and history of the head clog can be grasped, and measures for head clogging should be taken at an earlier stage before error processing by parity code etc. after processing the signal during recording and playback. It is possible to reduce the processing time of the head clocking countermeasure, to prevent the apparatus itself from being stopped, and to prevent a record that is invalid in terms of recording from remaining on the recording medium and causing waste. it can.

According to a second aspect of the present invention, the conversion means numerically converts the reproduction output level of the tracking signal in the signals recorded on the magnetic recording medium by the plurality of recording heads. As a result, the tracking signal can be used for head clocking detection, and the state and history of the head clog can be detected without performing any special countermeasures.

According to a third aspect of the present invention, a clog countermeasure for judging the result of observation by the output level history observing means, judging the clogging phenomenon of each of the recording head and the reproducing head, and executing a countermeasure against the clogging phenomenon. Means is provided. Thus, a head cleaner, retry of recording and reproduction, cleaning with a cleaning tape, and the like can be selected and executed according to the state of the head clog, and effective countermeasures can be executed.

[Brief description of the drawings]

FIG. 1 is a block diagram of a helical scan type magnetic recording device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a SAT track format of the embodiment of the helical scan magnetic recording device shown in FIG.

FIG. 3 is an explanatory diagram of RF level detection and a state transition of the device in the embodiment of the helical scan type magnetic recording device shown in FIG. 1;

FIG. 4 is a flowchart of a head clocking determination process in the embodiment of the helical scan type magnetic recording device shown in FIG. 1;

[Explanation of symbols]

1 ... recording head, 2 ... reproduction head, 3 ... head changeover switch, 4 ... preamplifier, 5 ... rotary transformer, 6 ... equalizer, 7 ... recording control device,
8: RF envelope detection circuit, 9: A / D converter, 10: Tracking error detection circuit, 11: System control and servo control CPU, 12: Head cleaner, 13: Driving amplifier, 14 ... ... CTL amplifier, 15 ... Control motor, 16 ... CTL head, 17
... Erase head, 18... Processing block, 19.

Claims (3)

[Claims] 1. A magnetic recording apparatus having a plurality of recording heads and a reproducing head, and performing helical scanning of the recording head and the reproducing head to perform recording and reproduction on a magnetic recording medium. Conversion means for numerically converting a reproduction output level of a reproduction signal obtained by reproducing a signal recorded on a recording medium using each of the recording head and reproduction head; and reproduction of each of the recording head and reproduction head converted by the conversion means. A magnetic recording apparatus comprising: output level history observing means for observing a history of numerical values of output levels. 2. The magnetic recording apparatus according to claim 1, wherein said converting means numerically converts a reproduction output level of a tracking signal among signals recorded on said magnetic recording medium by said plurality of recording heads. . 3. A clog countermeasure means for judging a result of observation by the output level history observing means, judging a clogging phenomenon of each of the recording head and the reproducing head, and executing a countermeasure against the clogging phenomenon. 3. The magnetic recording apparatus according to claim 1, wherein