JPH09297902A - Magnetic recording / reproducing device - Google Patents

Abstract

(57) Abstract: A magnetic recording and reproducing apparatus using an MR element,
If a read error occurs due to the occurrence of Uighur,
Uighur is compensated to recover the read error. If the read error is not recovered even after repeated re-reading, the bias current control circuit 10 stops the bias current flowing through the MR element 1 outside the servo area, and then supplies the bias current again. This corrects the magnetic domain imbalance of the MR element 1 and recovers the read error caused by the wiggle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing apparatus equipped with an MR head (magnetoresistive head), and is characterized by having a function of recovering a read error.

[0002]

2. Description of the Related Art In a conventional thin film magnetic head, when a read error occurs due to a phenomenon called wiggle, it is necessary to recover the read error. The wiggle is a phenomenon in which the reproduced signal waveform during reading is wavy, which is caused by the magnetic domain structure of the thin film magnetic head at the end of recording. This magnetic domain structure slightly changes with each write operation, and wiggle occurs when a certain unstable magnetic domain structure is taken.

Conventionally, when a read error occurs,
The following recovery process was performed. That is, the sector in which the error has occurred is reread until the number of times reaches a predetermined number. If the data cannot be read normally even with this, a recording operation of several bytes is performed in the gap byte where no signal is recorded.

By forcibly directing the magnetic domains in one direction by the magnetic field generated by the recording operation, the magnetic domains of the thin film head, which is the source of the wiggle, are moved to correct the imbalance of the magnetic domains. After that, by re-reading the sector in which the error occurred, the read error due to the wiggle was recovered.

[0005]

However, such read error recovery processing can be applied because the thin-film magnetic head has a structure in which the recording head and the reproducing head are used in common, but the recording head and the reproducing head are separated from each other. MR
Not applicable on the head. Therefore, even in the MR head, it is required to recover the read error due to the wiggle.

[0006]

In order to solve this problem, the present invention eliminates the bias current flowing through the MR element once in order to correct the imbalance of the magnetic domain orientation of the MR element. It is characterized by.

Accordingly, it is an object of the present invention to enable compensation even when an wiggle occurs in an MR head having a recording head and a reproducing head separated from each other.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the magnetic recording / reproducing apparatus according to the first aspect of the present invention, when reproducing a signal recorded on a magnetic recording medium by an MR element, a read error is not recovered even if re-reading is repeated. At this time, the bias current flowing through the MR element is stopped outside the servo area, and then the bias current is supplied again before the reproduction, whereby the direction of the magnetic domain of the MR element that causes the wiggle is unbalanced. The balance can be corrected and the read error can be recovered.

An embodiment of the invention described in claim 1 of the present invention will be described below with reference to FIGS. 1 and 2. 1 is a block diagram of a magnetic recording / reproducing apparatus according to Embodiment 1 of the present invention, and FIG. 2 is an operation explanatory diagram showing a process for recovering a read error of the apparatus.

In FIG. 1, the signal written on the magnetic disk 2 is reproduced by the MR element 1, and the MR preamplifier 3
After being amplified at, it is sent to the data channel 4. The detection signal detected by the data channel 4 is demodulated by the decoder (DEC) 11 inside the controller 5.

When a read error occurs during this reproduction, the internal R inside the microprocessor unit (MPU) 6 is read.
According to the program stored in the OM 12, the sector in which the error has occurred is reread until the number of times reaches a predetermined number, and recovery of the read error is attempted.

Because the wiggle occurs due to the imbalance of the magnetic domains of the MR element 1, if the MR element 1 does not recover even after repeated reading, the MR element 1 is out of the servo area, that is, the servo signal of the magnetic disk 2 is recorded. Drive to a location that does not exist and perform the following read error recovery processing.

That is, a bias current control circuit 1 including a D / A converter (DAC) 13 and a buffer (BF) 14.
When 0 is used, the bias current Ib flowing through the MR element 1 is once stopped from flowing outside the servo area, and then the bias current Ib is supplied again. The reason that the bias current is turned off outside the servo area is that the servo signal cannot be detected when the bias current stops flowing in the servo area, and the servo deviates.

FIG. 2A shows the direction of the magnetic domains of the MR element 1 when the wiggle is occurring, and FIG. 2B shows the reproduced signal waveform at this time. 2C shows the direction of the magnetic domain when the bias current Ib is turned off, and FIG. 2D shows the reproduced signal waveform at this time.

The bias current Ib flowing through the MR element 1 is
The output voltage of the bias current control circuit 10 is Ve, the potential of the bias current setting resistor 8 on the bias current setting circuit 7 side is V
b, the resistance value of the bias current setting resistor 8 is R, and the bias current gain is Ab, Ib = Ab * (Vb−Ve)
/ R. Therefore, by setting the output voltage Ve of the bias current control circuit 10 to Ve = Vb, Ib = 0
That is, the bias current Ib flowing through the MR element 1 can be turned off. When the bias current Ib is supplied again, the output voltage of the bias current control circuit 10 may be returned to the value set before turning off the bias current.

When the bias current Ib is turned off and on, the bias magnetic field is once removed, and the magnetic domain is set to the non-biased state. Then, the bias magnetic field is applied to the magnetic domain in the MR element again, whereby the direction of the magnetic domain of the MR element is changed. Can be moved. As a result, the imbalance in the orientation of the magnetic domains of the MR element can be corrected, and the read error due to the wiggle can be recovered by rereading. Note that FIG. 2E shows the state of the orientation of the magnetic domains when the bias current Ib is flown again, and FIG. 2F shows the reproduced signal waveform at this time, and the reproduced waveform distortion due to the wiggle is shown. It has been removed.

In the above description, the bias current control circuit 10 is composed of the D / A converter 13 and the buffer 14 so that the bias current setting current does not flow through the bias current setting resistor 8. Alternatively, a configuration may be used in which the bias current setting resistor 8 and the bias current setting circuit 7 are opened by using a transistor switch or the like.

[0018]

As described above, in the magnetic recording / reproducing apparatus of the present invention, when the recording signal is reproduced by the MR element, when the read error is not recovered even if the reading is repeatedly performed due to the generation of the wiggle, the servo is reproduced. The bias current flowing through the MR element outside the region was turned off and then turned on again. This can correct the imbalance of the magnetic domain orientation of the MR element and recover the read error.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration for recovering a read error according to an embodiment of the present invention.

FIG. 2 is an operation explanatory diagram of a read error recovery process in the same embodiment.

[Explanation of symbols]

 1 MR element 2 magnetic disk 3 MR preamplifier 4 data channel 5 controller 6 microprocessor unit 7 bias current setting circuit 8 bias current setting resistor 10 bias current control circuit

Claims (1)

[Claims] 1. When reproducing a signal recorded on a magnetic recording medium by an MR element, when a read error is not recovered even after re-reading, a bias current flowing through the MR element is stopped from flowing outside the servo area. After that, the magnetic recording / reproducing apparatus is adapted to reproduce the magnetic field after applying the bias current again.