JP2557941B2 - Magnetic recording device having read error recovery function - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording device equipped with a thin film magnetic head, and more particularly to a magnetic recording device having a read error recovery function.

[Prior Art] A conventional magnetic recording device, for example, a magnetic disk device, has a configuration as shown in FIG. 3 as described in JP-A-57-203264. In FIG. 3, the recording medium 2 is driven by the spindle 3, and the magnetic head 1 is positioned on the recording medium 2 by the positioning mechanism 4. When recording a signal, a recording / reproducing amplifier circuit 8 converts a signal sent via a disk controller (hereinafter abbreviated as DKC) 9 into a current signal and applies it to the magnetic head 1 in response to a command from the CPU 10. The magnetic field of the magnetic head 1 generated by the application of this current is recorded on the medium 2 as magnetization information. For reproducing the signal, the magnetization information recorded on the recording medium 2 is transferred to the magnetic head 1.
Is converted into an electric signal through the recording / reproducing amplifier circuit 8 and detected as a signal. In the reproducing process, when a read error occurs, the retry operation function operates based on the judgment of DKC9, and the offset operation function calls the positioning circuit 7 for offset and start. The positioning circuit 7 that receives this operation command controls the positioning mechanism 4 and repeats the offset operation so that the read margin is maximized.

[Problems to be Solved by the Invention]

When the thin film magnetic head is used in the magnetic recording device, the above-mentioned conventional technique does not consider when a read error occurs due to a phenomenon called wiggle peculiar to the thin film magnetic head, and recovery of the read error based on this phenomenon is not considered. There was a problem that it was difficult.

The phenomenon of wiggle peculiar to the thin film head will be described with reference to FIG. The phenomenon of wiggle is a phenomenon in which the reproduced signal waveform during reading is rippling, as shown in the reproduced signal waveforms of FIGS. 2 (c) and 2 (f), which is the magnetic domain of the thin film magnetic head at the end of recording. Accidental due to structure. This magnetic domain structure changes minutely with each write operation, and it is said that wiggle occurs when a certain unstable magnetic domain structure is taken.

In the magnetic disk device, when detecting data, a signal pulse is formed at the peak of a reproduced signal waveform, the signal pulse is applied to a signal discrimination window, and the data is detected by the presence or absence of the signal pulse in the signal discrimination window. However, in the reproduction signal waveform 13 generated by the wiggle 20 as shown in FIG. 2 (c), its peak is deviated, and therefore, FIG. 2 (b).
Since the position of the signal pulse 12 deviates as shown in FIG. 3, a read error occurs from the position of the signal discrimination window 11 shown in FIG. In addition, Uighur as shown in FIG. 2 (f)
A pseudo peak occurs in the reproduced signal waveform 13 'generated by 20', and a signal pulse 12 'is generated in the signal discrimination window 11 shown in FIG. 2 (d) as shown in FIG. 2 (e). There is an individual and a read error occurs.

The signal discriminating window is inevitably further narrowed due to the ever-increasing recording density of magnetic disk devices, and the probability that a read error will occur due to the occurrence of wiggle increases. Therefore, solving this problem is an important issue.

An object of the present invention is to provide a magnetic recording device having a function of recovering a read error even when a Uighur phenomenon peculiar to a thin film magnetic head occurs.

[Means for solving the problem]

In the magnetic recording device for writing and reading the magnetic recording medium by the thin film magnetic head, a means for detecting a read error, a means for instructing a retry operation based on the detected read error, and a predetermined retry operation are provided. It is achieved by a magnetic recording apparatus having a read error recovery function, characterized in that it has a means for judging that the number of times has been repeated and a means for carrying out a predetermined write operation based on the judgment.

[Action]

In the present invention, the thin film magnetic head is caused to perform the write operation between the retry operations for recovering the read error.

The phenomenon of wiggle occurs when the thin film magnetic head has a magnetic domain structure. This magnetic domain structure changes minutely each time the magnetic head performs a write operation. The write operation performed between the retry operations acts to change the magnetic domain structure of the magnetic head.
As a result, the wiggle generated by the magnetic domain structure before the write operation often disappears, so that the read error generated by the wiggle can be recovered.

〔Example〕

 Hereinafter, an embodiment of the present invention will be described with reference to FIG.

In FIG. 1, the recording medium 2 is driven by a spindle 3, and the magnetic head 1 is positioned on the recording medium 2 by a positioning mechanism 4. When recording a signal, the recording / reproducing / amplifying circuit 8 converts the signal sent to the recording / reproducing / amplifying circuit 8 via the DKC 9 according to a command from the CPU 10 into a current signal and applies it to the magnetic head 1. The magnetic field of the magnetic head 1 generated by this applied current is recorded on the recording medium 2 as magnetization information. When reproducing a signal, the recorded magnetization information is converted into an electric signal through the magnetic head 1 and detected through the recording / reproducing amplifier circuit 8. If a read error occurs at this time, the DKC9 that detected the read error first activates the retry operation function and then the offset operation function to recover the read error, as before. However, if the read error is not recovered even in this operation, the next operation is executed. When the DKC9 detects that the read error is not recovered, it activates the return and rewrite operation function and controls the positioning mechanism 4 via the positioning circuit 7 to influence the magnetic head 1 on the recording / reproduction on the recording medium 2. Then, the magnetic head 1 is caused to perform a write operation. At this time, the write current and write frequency are sufficient within the range normally used by the device. After that, the positioning mechanism 4 is controlled via the positioning circuit 7 based on the command of the return and rewrite operation function to reposition the magnetic head 1 to the original track position and perform the read operation.

When the read error is not recovered by the above operation, the offset operation and the return and rewrite operation functions are repeatedly operated to recover the read error.

According to this embodiment, it is possible to recover the read error due to the Uighur phenomenon peculiar to the thin film magnetic head.

Note that FIG. 4 is a flowchart in the case where FIG. 1 is operated. m, l indicates a certain number of times.

〔The invention's effect〕

According to the present invention, since the read error can be recovered by the wiggle generated at the corner, the reliability of the magnetic disk device can be improved. Further, since it is possible to use a thin film magnetic head, which has conventionally been poor in performance due to the generation of wiggle, there is an effect that the yield of the thin film magnetic head is improved and a low cost magnetic disk device is obtained.

[Brief description of drawings]

FIG. 1 is a block diagram of a magnetic disk device having a read error recovery function according to an embodiment of the present invention, and FIG. 2 is a relation between a reproduction signal waveform generated by a wiggle, a signal pulse and a signal discrimination window. FIG. 3 is a configuration diagram of a conventional magnetic disk device having a read error recovery function, and FIG. 4 is an explanatory diagram showing the operation of the magnetic disk device of one embodiment of the present invention. 1 ... Magnetic head, 2 ... Recording medium 3 ... Spindle, 4 ... Positioning mechanism 7 ... Positioning circuit, 8 ... Recording / reproducing amplifier circuit 9 ... Disk controller (DKC) 10 ... CPU, 11 ... Signal discrimination window 12,12 '... Signal pulse 13,13' ... Playback signal waveform 20,20 '... Uighur

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takuji Ogawa 2880 Kokufu, Odawara-shi, Kanagawa Hitachi Co., Ltd.Odawara factory (72) Inventor Tatsuo Saito 2880 Kunifu, Odawara, Kanagawa Hitachi, Ltd. Odawara factory (72) Inventor Yoshiaki Karakama 2880, Kozu, Odawara-shi, Kanagawa Hitachi Co., Ltd.Odawara Plant (72) Inventor, Akira Kurano 2880, Kozu, Odawara, Kanagawa Hitachi Ltd. Odawara Plant (72) Inventor Hiroyuki Minami 2880 Kozu, Odawara City, Kanagawa Prefecture Odawara Factory, Hitachi Ltd.

Claims (1)

(57) [Claims] 1. A magnetic recording apparatus for writing and reading data on a magnetic recording medium by a thin film magnetic head, a means for detecting a read error, a means for instructing a retry operation based on the detected read error, and the retry operation. A magnetic recording apparatus having a read error recovery function, comprising: a means for judging that a predetermined number of times has been repeated and a means for carrying out a predetermined writing operation based on the judgment.