JP2001143209A - Magnetic disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the overwrite characteristic in a magnetic disk device. SOLUTION: In this magnetic disk device, a measuring means 112 is provided for measuring the overwrite characteristic of the magnetic disk 102, and the optimum recording current value determined from the measurement result of this measured overwrite characteristic is obtained from a memory 105, then data are recorded by using this optimum recording current value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk drive in which the overwrite characteristics of a magnetic disk are taken into account.
In particular, the present invention relates to a magnetic disk drive capable of always recording data with an optimum recording current value even when a temperature condition changes and improving data reliability.

[0002]

2. Description of the Related Art In general, when writing data on a magnetic disk as a recording medium, a magnetic disk device performs overwrite recording on previously written data. Become. This overwrite characteristic is shown in FIG. 7 on a magnetic disk in which a signal SIG1 is written at a frequency f1 shown in the figure and the reproduced signal becomes a reproduced signal having a peak only at the frequency f1 as shown in FIG. When the signal SIG2 of the frequency f2 is written, in addition to the fact that the reproduced signal has a peak of the frequency f2 as shown in FIG. In other words, the signal of the frequency f1 remains, and the remaining amount is called an overwrite characteristic, and it is desired to reduce as much as possible.

In order to improve the overwrite characteristic, that is, to reduce the remaining erase amount, the recording current value is clearly understood from FIG. It is known that should be increased. In the example of FIG.
When the value is equal to or larger than mA, the overwrite indicated by the mark Δ decreases. However, if the recording current value is too large as shown in FIG. 6, the recording demagnetization occurs, and as shown by a circle, there occurs a problem that the output of the reproduction signal is reduced.

Therefore, it is preferable to set the recording current value as small as possible within a range where the overwrite characteristic is saturated. However, since this overwrite characteristic differs depending on the combination characteristics of the magnetic head and the recording medium or the recording density, etc. The optimum recording current value differs depending on the individual device.If data is written to the magnetic disk at a non-optimal recording current value, the read error rate will deteriorate. It is set so that the recording current value is obtained and the data is stored.

[0005]

In the magnetic disk drive according to the prior art described above, the optimum recording current value is set at the time of shipment or when the apparatus is started up, but the temperature condition is set during the actual use of the magnetic disk drive. As the temperature changes to a very low temperature, the magnetic characteristics of the recording medium change, and the recording current value at which the overwrite characteristics are saturated shifts, resulting in a problem that the optimum recording current value changes. .

Therefore, in the magnetic disk device according to the prior art, when data is written with the optimum recording current value obtained in advance, the read error rate is deteriorated, and the deterioration of the read error rate is determined at the time of data writing. Therefore, the read error rate at the time of data reproduction remains deteriorated regardless of the temperature condition, which may cause a problem that the reliability of the magnetic disk device is greatly reduced. In particular, the use environment of recent magnetic disk devices is used in notebook and mobile personal computers and portable terminals, and when used in extremely cold regions, the overwrite characteristics set at the time of manufacture will change and the read error rate will increase. Of the magnetic disk drive, which may cause a problem that the reliability of the magnetic disk device is greatly reduced. On the other hand, a similar problem also occurs when the magnetic disk device is used in a high-temperature environment. .

The reason for the change in the overwrite characteristics due to the change in the temperature condition is that the medium coercive force (Oe) of the magnetic recording film on the magnetic disk, that is, the difficulty in writing data changes due to the temperature change. It is considered that as a result, the unerased portion of the overwriting changes.

An object of the present invention is to eliminate the above-mentioned disadvantages of the prior art, and to provide a magnetic disk drive capable of maintaining an overwrite characteristic at an appropriate value regardless of a use environment.

[0009]

In order to achieve the above object, the present invention provides a magnetic disk, a magnetic head for recording and reproducing data on the magnetic disk, and controlling the recording and reproduction of data via the magnetic head. In a magnetic disk device including a recording / reproducing circuit, a first method is to measure overwrite characteristics of the magnetic disk and record data using an optimum recording current value obtained from a measurement result of the measured overwrite characteristics. Features.

The present invention also provides a magnetic disk, a magnetic head for recording and reproducing data on the magnetic disk, a recording and reproducing circuit for controlling recording and reproduction of data via the magnetic head, and a magnetic disk and a magnetic head. A magnetic disk drive having a housing that integrally stores the temperature and the temperature of the inside or outside of the housing, and reads out from a memory an optimum recording current value corresponding to the detected temperature. The second feature is that data is recorded using the value.

Further, the present invention relates to a magnetic disk device comprising a magnetic disk, a magnetic head for recording and reproducing data on the magnetic disk, and a recording and reproducing circuit for controlling recording and reproduction of data via the magnetic head. A third feature is that the magnetic characteristics of the magnetic disk are measured, an optimum recording current value corresponding to the measured magnetic characteristics is read from the memory, and data is recorded using the optimum recording current value.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a magnetic disk drive according to an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing the configuration of the magnetic disk drive according to the present embodiment. The magnetic disk drive according to the present embodiment has the configuration shown in FIG.
As shown in FIG.
2, a magnetic head 101 for recording and reproducing data on and from the magnetic disk 102, a preamplifier 103 for amplifying a recording signal and a reproduction signal for the magnetic head 101, and an automatic gain control for the reproduction signal via the preamplifier 103. AGC 107 for controlling the amplitude to be constant and the preamplifier 1
03, a pulse generator 106 for supplying a variable frequency recording signal (sinusoidal data pattern), a memory 105 for storing an optimum current value of the recording current for the magnetic head 101, and reproduction by the magnetic head 101. And a high-pass filter 1 that passes high-frequency and low-frequency signals of the reproduction signal through the preamplifier 103 and the AGC 107.
08 and a low-pass filter 109, and an AD converter 11 for AD-converting a reproduction signal from the low-pass filter 109
0, a logic circuit 111 for processing the digitally converted reproduced signal, a level detecting means 113 for measuring the magnitude of an output signal of the signal processing means 112, and a timer 115 used as time monitoring means for measuring time. And a CPU 104 for controlling these mechanical circuits.

The high-pass filter 108 and the low-pass filter 109 each have a structure in which a cutoff frequency can be variably set, and constitute a signal processing means 112 in which the combined characteristics of the two filters have band-pass characteristics. are doing. The signal processing means 112 and the level detection means 1
Reference numeral 13 denotes an overwrite characteristic measuring unit 114 which is a feature of the present embodiment. Further, the timer 115
Is to periodically update the optimum recording current value stored in the memory 105 at a certain time interval T from the time monitoring result.

The magnetic disk drive configured as described above has a C
In accordance with an instruction from the PU 104, data is recorded and reproduced on and from the magnetic disk using the magnetic head 101.
The overwrite characteristic of the device is measured by the overwrite characteristic measuring means 114, and this operation will be described below.

In the magnetic disk device according to the present embodiment, in order to measure the above-mentioned overwrite characteristic, the frequency of the data pattern generated from the pulse generator 106 is first set to f1 and the frequency is set to the measurement area on the magnetic disk 102. A reference sinusoidal data pattern (signal SIG1 shown in FIG. 7) is recorded, and the frequency of the data pattern generated from pulse generator 106 is set to f2.
(F1 ≠ f2) is set and a sine wave data pattern (SIG2) is written so as to overwrite the SIG1.

Next, in this apparatus, the signal processing means 112
The high-pass filter 108 and the low-pass filter 109 so that the frequency component of the band-pass characteristic that can pass is f1.
And the cut-off frequency is appropriately set, and the written recording signal is reproduced.

In the reproduced signal after the rewriting, the remaining unerased component of the frequency f1, which is the unerased component of the SIG1, is shown in FIG.
Therefore, the present apparatus extracts only the component of the frequency f1 by using the signal processing means 112, and measures the magnitude of the signal by the level detection means 113.
The overwrite characteristics are measured. The optimum value of the overwrite characteristic differs depending on the combination characteristic of the magnetic head and the recording medium, the recording density, and the like.
The CPU 104 sets the recording current value to be supplied to the magnetic head at the time of data writing by the preamplifier 103 to various values, measures the overwrite characteristics at that time, and obtains the optimum overwrite characteristics. The recording current value which can be obtained can be known, and this recording current value is recorded in the memory 105. Further, the CPU 104 measures, for example, the above-described overwrite characteristic from the time monitoring result of the timer 115, and periodically updates the optimum recording current value stored in the memory 105 at a certain time interval T.

Therefore, the magnetic disk drive according to the present embodiment is provided with the overwrite characteristic measuring means 11 at predetermined time intervals.
4 measures the overwrite characteristics of its own device, and adjusts the recording current value passed to the magnetic head at the time of data writing by the preamplifier 103 and records it in the memory 105 so that the optimum value is obtained. Even in this case, it is possible to always maintain the optimal overwrite characteristics and improve the reliability of the recording data.

In the above embodiment, the data is actually rewritten, and the overwrite characteristic is measured each time.
The preamplifier adjusts the recording current value that flows to the magnetic head when writing data so that the optimum value is obtained.
The present invention can monitor and adjust the overwrite characteristics by other methods, and another embodiment will be described below.

First, as described above, the overwrite characteristic has a characteristic that the magnetic characteristic of the recording medium changes depending on the temperature condition in which the magnetic disk device is used or the like and changes with time. Therefore, by monitoring the temperature inside or outside the device, the overwrite characteristic can be indirectly known.

FIG. 2 shows the configuration of a magnetic disk drive which indirectly detects and adjusts the overwrite characteristics based on this temperature detection. This magnetic disk drive includes a magnetic head 201, a recording medium 202, a preamplifier 20 as in the first embodiment.
3, a CPU 204, a memory 205, a timer 215, and a thermometer 217 for measuring a temperature inside or outside a housing for accommodating a magnetic disk or the like in addition to a normal configuration such as a waveform equivalent circuit 216. Stores, as a table, a temperature and a recording current value that provides an optimum overwrite characteristic corresponding to the temperature. The factor stored in the table is not limited to the temperature, but may be any factor whose value changes in response to a temperature change such as an optimum recording current value corresponding to the temperature.

The relationship between this temperature and the recording current value at which the overwrite characteristic is optimal corresponding to the temperature is, for example, as shown in FIG. 3 when the temperature is outside the housing, when the temperature is 0 ° C., about 45 mA. When the temperature is 55 ° C., it is set to about 30 mA. The operating temperature of a small magnetic disk device generally used for mobile devices is approximately 0 ° C. to approximately 5 ° C.
Since 5 ° C. is desired and changes to about + 15 ° C. to 20 ° C. by linking to the outside temperature inside the housing, when detecting the temperature inside the sphere, the temperature in the example of FIG. It is conceivable to use a table set at +15 degrees C to 20 degrees C.

The magnetic disk drive configured as described above has a C
In accordance with an instruction from the PU 204, data is recorded on and reproduced from the magnetic disk using the magnetic head 201, and
The temperature detected by the thermometer 217 is fetched at predetermined time intervals by the timer 215, and the optimum recording current value of the preamplifier 203 is read from the memory 205 by this temperature change, and the magnetic head 201 uses the read recording current value to read the optimum recording current value. Operates to write data.

Therefore, the magnetic disk drive according to the present embodiment detects the temperature inside or outside the housing, and adjusts the write current value of the magnetic head according to the detected temperature, thereby indirectly detecting the overwrite characteristic. And keep it at an appropriate value.

FIG. 4 is a view for explaining a magnetic disk drive according to still another embodiment of the present invention. The magnetic disk drive according to the present embodiment includes a magnetic head 401, a recording medium 402, a preamplifier 403,
In addition to the normal configuration of the CPU 404, the memory 405, the timer 415, the waveform reproducing circuit 416, etc., a magnetic characteristic measuring unit 418 for measuring the medium coercive force of the magnetic recording film of the magnetic disk.
It is constituted so that it may be provided.

The magnetic characteristic measuring means 418 utilizes the characteristic of the overwrite characteristic that the magnetic characteristic of the recording medium is displaced due to the temperature change of the magnetic disk, and measures the magnetic characteristic, specifically, the medium coercive force of the magnetic recording film. To measure,
The memory 405 stores, as a table, a medium coercive force Oe and a recording current value that provides optimum overwrite characteristics corresponding to the coercive force Oe. The factors stored in the table are not limited to the medium coercive force, but may be any as long as the values change in accordance with a change in the medium coercive force such as an optimum recording current value corresponding to the medium coercive force.

The relationship between the coercive force Oe and the recording current value that provides the optimum overwrite characteristic corresponding to the coercive force Oe is, for example, as shown in FIG. 5, when the coercive force is 2800 (Oe).
Is set at about 30 mA, and when the coercive force is 3300 (Oe), about 45 mA.

The magnetic disk device configured as described above has a C
In accordance with an instruction from the PU 404, data is recorded on and reproduced from the magnetic disk using the magnetic head 401.
The magnetic characteristic measuring means 418 measures the medium coercive force Oe at predetermined time intervals by the timer 415, reads out the optimum recording current value of the preamplifier 403 from the memory 405 based on the change in the coercive force, and reads the read recording current value. It operates so as to write data by the magnetic head 401 using the data.

Therefore, the magnetic disk device according to the present embodiment measures the medium coercive force of the magnetic disk and adjusts the write current value of the magnetic head according to the measurement result, thereby indirectly detecting the overwrite characteristic. , Can be kept at an appropriate value. Incidentally, the magnetic characteristic measuring means 418
For example, a method utilizing the magnetic Kerr effect due to a change in magnetic characteristics can be considered, but the present invention is not limited to this.

As described above, the magnetic disk drive according to the above-described embodiment performs the data recording / reproduction to directly detect the overwrite characteristic, or detects the temperature or medium coercive force to indirectly detect the overwrite characteristic. By writing data with a magnetic head using a write current value preset in the memory according to the detection result,
Even if the temperature condition changes during the use of the device, the optimum recording current value at that time can be obtained, and the data can always be written to the recording medium with the latest optimum recording current value. Of the magnetic disk drive can be prevented, and the reliability of the magnetic disk drive can be improved.

The present invention can be described as the following embodiments. <Embodiment 1> A means for measuring overwrite characteristics, a storage means for storing an optimum recording current value obtained from the measurement results of the overwrite characteristics, and a lapse of time is measured, and the storage contents of the storage means are periodically updated. A magnetic disk drive, comprising: a time monitoring means for updating the recording current, and always maintaining an optimum recording current value when writing data to a recording medium.

<Second Embodiment> A magnetic disk drive according to the first embodiment, having a temperature measuring means instead of a means for measuring overwrite characteristics, and obtaining an optimum recording current value from the measurement result.

<Embodiment 3> In Embodiment 1, instead of the means for measuring the overwrite characteristic, there is provided a magnetic characteristic measuring means which is located in contact with or near the recording medium and measures its magnetic characteristic. A magnetic disk drive that determines the optimum recording current value from the results.

[0034]

According to the present invention, even if the optimum recording current value when the magnetic disk drive writes data to the recording medium changes with time due to temperature conditions, etc., the latest optimum recording current value is always known, and the latest optimum recording current value is obtained. The data can be written to the recording medium by the value, and the reliability of the recorded data is improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a magnetic disk drive that measures and adjusts overwrite characteristics according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a configuration of a magnetic disk drive that measures and adjusts overwrite characteristics according to a second embodiment of the present invention.

FIG. 3 is a diagram showing a relationship between a temperature and an optimum recording current value.

FIG. 4 is a diagram showing a configuration of a magnetic disk device that measures and adjusts a medium coercive force according to a third embodiment of the present invention.

FIG. 5 is a diagram showing a relationship between a medium coercive force and an optimum recording current value.

FIG. 6 is a diagram showing a relationship between a recording current value, an overwrite characteristic, and a reproduction signal output.

FIG. 7 is a diagram for explaining overwrite characteristics in the magnetic disk device.

[Explanation of symbols]

101: magnetic head, 102: recording medium, 103: preamplifier, 104: CPU, 105: memory, 106: pulse generator, 107: automatic gain control circuit (AG)
C), 108: high-pass filter, 109: low-pass filter, 110: AD converter, 111: logic circuit, 11
2 ... Signal processing means, 113 ... Level detection means, 114 ...
Means for measuring overwrite characteristics, 115 ... timer,
201 magnetic head, 202 recording medium, 203 preamplifier, 204 CPU, 205 memory, 215 timer, 216 waveform reproduction circuit, 217 thermometer, 401
.., A magnetic head, 402, a recording medium, 403, a preamplifier, 404, a CPU, 405, a memory, 415, a timer, 416, a waveform reproducing circuit, and 418, a magnetic characteristic measuring means.

Claims (3)

[Claims] 1. A magnetic disk drive comprising: a magnetic disk; a magnetic head for recording and reproducing data on the magnetic disk; and a recording and reproducing circuit for controlling recording and reproduction of data via the magnetic head. A magnetic disk device which measures overwrite characteristics and records data using an optimum recording current value obtained from the measured results of the overwrite characteristics. 2. A magnetic disk, a magnetic head for recording and reproducing data on the magnetic disk, a recording and reproducing circuit for controlling recording and reproduction of data via the magnetic head, and the magnetic disk and the magnetic head are integrated. In a magnetic disk device comprising a housing for temporarily storing, an internal or external temperature of the housing is detected, an optimal recording current value corresponding to the detected temperature is read from a memory, and the optimal recording current value is used. A magnetic disk drive for recording data by using a magnetic disk drive. 3. A magnetic disk device comprising: a magnetic disk; a magnetic head for recording and reproducing data on the magnetic disk; and a recording and reproducing circuit for controlling recording and reproduction of data via the magnetic head. A magnetic disk device which measures magnetic characteristics, reads an optimum recording current value corresponding to the measured magnetic characteristics from a memory, and records data using the optimum recording current value.