JPH04134706A - Magnetic disk medium and magnetic disk device - Google Patents

Abstract

PURPOSE:To easily execute the optimization of the tap gain of an equalizer by recording an isolation wave signal for a half-value width measurement. CONSTITUTION:The isolation wave for the half-value width measurement is preliminarily written in the index part of all cylinders or an optional cylinder. Then the measurement of the half-value width is executed by using a half-value width detection circuit 7, and the tap gain of an equalizer 4 is switched based on that value. Then, even when a variation in the peak shift value by the head is present thereon, the gap gain can be set at an optimum value at the same time as when the values of the head and the cylinder are changed by the access from a microprocessor, and the value of the peak shift can be made minimum. Thus, the peak shift is reduced, the margin at the time of read-out data pulse output is expanded, and the generation of read-out error is prevented.

Description

TECHNICAL FIELD The present invention relates to magnetic disk media and magnetic disk drives, and more particularly to peak shift compensation of read pulses from the medium.

2. Description of the Related Art In general, when a single pulse is written on a magnetic medium in a magnetic disk device or a floppy disk device, the output waveform becomes a single solitary wave, that is, a waveform that is not affected by adjacent waveforms. However, data that is normally written in response to this solitary wave has a short time interval between data, and the data interfere with each other, resulting in a peak shift.

For example, if the pulse interval is short as shown by the broken line as shown in FIG. 6, the actual readout waveform will be the waveform shown by the solid line. In such a case, the peak shift is 0 in part A in the figure, but in parts B and 0, a peak shift occurs due to waveform interference, causing the signal peak to shift from its original position, resulting in readout errors, etc. Occur. Note that the broken lines in the figure are virtual output waveforms when data is read individually.

In order to prevent the occurrence of read errors due to such peak shifts, conventional magnetic disk drives use equalizers and compensate for peak shifts by switching the tap gain of the equalizer. The configuration of the conventional magnetic disk device will be explained using FIG. 2. FIG. 2 is a block diagram showing the configuration of a conventional magnetic disk device. In the figure, a conventional magnetic disk device includes a magnetic disk medium 10a and an IC 1b that are rotationally driven by a spindle motor 11,
Magnetic heads 98 to 9d that read and write data, and read/write I that controls reading and writing of each magnetic head.
C2, and a low-pass filter 3 that cuts high-frequency noise of the signal read by the read/write IC and passes low-frequency noise.

In addition, the conventional magnetic disk device has a low-pass filter 3.
An equalizer 4 reduces the peak shift by pulse slimming the reproduced waveform from the output, a differentiating circuit 5 differentiating the waveform, and outputting a read data pulse by detecting the zero-crossing point of the signal that has passed through the differentiating circuit 5. It is configured to include a zero cross comparator 6 and a microprocessor 1 that controls each part. Note that 8a to 8C are head arms.

In a conventional magnetic disk drive having such a configuration, in order to compensate for the above-mentioned peak shift, the tap gain of the equalizer 4 is changed to perform pulse slimming. The switching processing method will be explained using FIG. 3.

FIG. 3 is a waveform diagram showing a pulse slimming processing method within the equalizer. In the figure, if the input waveform Vin is Vin, the waveform delayed by T with respect to Vin is V
t, and let Vp be the one that is ahead and the one that is behind by T with respect to Vi.

At this time, the magnitude of the amplitude of Vp with respect to Vi is generally called the tap gain of the equalizer. In other words, when the amplitude of Vt and the amplitude of Vp are equal, the tap gain is 1,
If the amplitude of vp is 1/2 of the amplitude of Vi, the tap gain will be 0.5.

Further, Vs in the figure is obtained by superimposing the waveform of Vp with the magnitude of the tap gain set optimally. Then, by subtracting this Vs from Vi, V out is obtained. According to the above processing, by using the equalizer, the waveform of Vt becomes the waveform of V out, and the waveform becomes a waveform with narrow pulses. Making the pulse into a thin waveform in this manner is called pulse slimming processing.

The waveform after this pulse slimming process is not affected by other waves like the solitary wave described above, so that the peak shift is reduced.

However, in conventional magnetic disk drives using the above-mentioned equalizer, the
The tap gain of the equalizer was changed at one location or at several locations on the same cylinder. In other words, even though the resolution and half-width size differ depending on the magnetic head, because the tap gain switching cylinder is the same for all heads, the value of the peak shift that is reduced by equalizer pulse slimming varies depending on the head. There was a drawback. Therefore, it is not possible to set the tap gain of the equalizer to an optimal value according to each head, resulting in a reduction in margin and, in the worst case, a problem in that it causes a read error.

OBJECT OF THE INVENTION The present invention has been made to solve the above-mentioned conventional drawbacks, and its purpose is to provide a magnetic disk in which an optimal tap gain can be set in an equalizer for each magnetic head and furthermore for each cylinder. The purpose is to provide equipment.

Another object of the present invention is to provide a magnetic disk medium that facilitates optimization of the tap gain of an equalizer.

Structure of the Invention The magnetic disk medium according to the present invention is characterized in that a solitary wave signal for half-width measurement is recorded.

A magnetic disk device according to the present invention includes a magnetic disk medium on which a solitary wave signal for half-width measurement is recorded, a reading means for reading out the solitary wave signal, and a means for measuring the half-width of the read solitary wave signal. The present invention is characterized in that the peak shift of the read pulse of the magnetic disk medium is compensated according to the value of the measured half-width.

Example Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of a magnetic disk device according to the present invention, and parts equivalent to those in FIG. 2 are designated by the same reference numerals.

The magnetic disk device of this embodiment differs from the conventional magnetic disk device (FIG. 2) in that a half-width detection circuit 7 is provided. In other words, in this example, the readout waveform is The tap gain of the equalizer is set according to the half-value width of . Therefore, in order to realize this, the magnetic disk medium 10a10b must be prepared in advance.
A solitary wave for half-width measurement is written in advance, and before reading data, the solitary wave is read out and its half-width is measured.

Note that, as shown in FIG. 5, the half width is the pulse width H of half the amplitude value when the peak value of the waveform is 1. Therefore, if 1/2 of the peak value is used as a threshold value, the half width can be easily measured.

Next, the internal configuration of the half-width detection circuit 7 will be explained.

FIG. 4 is a block diagram showing the internal configuration of the half-width detection circuit 7. In the figure, the half-width detection circuit 7 includes a data readout circuit 71 that reads out a solitary wave, a solitary wave amplitude measurement circuit 72 that measures the amplitude of the read solitary wave, and a half-width measurement circuit 72 that measures the amplitude of the solitary wave. The half-width measurement circuit 73 is configured to include a half-width measurement circuit 73 that performs the following.

In this configuration, before reading data, the data reading circuit 71 in the half-width detection circuit 7 reads a solitary wave written in advance on a magnetic disk medium (not shown). next,
A solitary wave amplitude measuring circuit 72 measures the amplitude of the solitary wave. Based on the measured value of the amplitude of this solitary wave, the half-width measurement circuit 73 measures the half-width using 1/2 of the amplitude as a threshold.

The half-width thus determined is sent to the microprocessor, and based on that value, the optimum value of the tap gain of the equalizer is set as described later.

Here, the above-mentioned solitary wave may be written in advance in the index portions of all heads and all cylinders on the magnetic disk medium. By doing so, the optimum tap gain can be set for each head and each cylinder. Alternatively, instead of writing to all cylinders of all heads, solitary waves may be written to the index section of any cylinder of each head, for example, to several locations between the outermost circumference and the innermost circumference of the medium. ,
It is sufficient to take the magnetic properties and bit density of the medium into consideration and write at intervals that do not cause read errors.

Returning to FIG. 1, the tap gain setting operation of the magnetic disk drive of this embodiment having such a configuration will be described.

In the figure, magnetic disk media 10a and 10b are constantly rotated by a spindle motor 11. The magnetic heads 98 to 9d write data to or read data from a constantly rotating magnetic disk medium.

The read/write IC 2 performs read/write control of the magnetic head 9 supported by the head arm 8 . The half-width detection circuit 7 reads the solitary wave written on the magnetic disk medium from the read/write IC 2 via the solitary wave detection signal line 21, and determines the value of the half-width.

The microprocessor 1 performs head select control of the read/write IC 2 via the head select signal line 20. Further, the microprocessor 1 takes in the half-width chain of each head and each cylinder determined by the half-width detection circuit 7 through the half-width transmission signal line 70, sets the cylinder whose tap gain needs to be changed, and switches the tap gain. The signal line 41 controls the tap gain setting of the equalizer 4.

Here, the tap gain of the equalizer is usually 0 to 0°3.
It is a value of degree, 0. It can be changed in steps of 01 to 003. Further, since the value of the half-value width and the value of the tap gain are generally in a substantially proportional relationship, when the value of the half-value width is large, the tap gain is set to a large value. This is because when the half-width is large, interference from adjacent pulses is likely to occur.

In other words, in a microprocessor, at key locations on the medium to prevent read errors from occurring,
All you have to do is set the cylinder whose tap gain should be changed. Therefore, at the device design stage, the optimal tap gain value for the half-value width may be determined and incorporated into the microprocessor as firmware.

The low-pass filter 3 is a read/write IC 2.
The high-frequency noise of the read signal is cut and the low-frequency noise is passed.

The equalizer 4 reduces the peak shift by pulse slimming the reproduced waveform from the low-pass filter 3 as described above. And zero cross comparator 6
outputs a read data pulse by detecting the zero-crossing point of the signal that has passed through the differentiating circuit 5.

Although the case of a magnetic disk device has been described above, it is clear that the present invention is applicable to both a so-called fixed disk system and a so-called disk back system.

It can also be applied to floppy disk devices.

In this case, solitary waves may be written when initializing or formatting the floppy disk medium.

Detailed Description of the Invention As described in detail, the present invention writes a solitary wave for half-width measurement in advance in all cylinders of all heads or index portions of arbitrary cylinders, and uses a half-width detection circuit to measure the half-width. By measuring and changing the tap gain of the equalizer based on the measured value, even if there is a variation in the peak shift value due to the head, the tap gain can be changed at the same time as the head and cylinder values are changed by access from the microprocessor. can be set to an optimal value, and the peak shift value can be minimized. This has the effect of reducing peak shifts, widening the margin when outputting read data pulses, and preventing read errors from occurring.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a magnetic disk device according to an embodiment of the present invention, FIG. 2 is a block diagram showing the configuration of a conventional magnetic disk device, and FIG. 3 is a waveform diagram showing the principle of pulse slimming processing. FIG. 4 is a block diagram showing the internal configuration of the half-width detection circuit, FIG. 5 is a diagram showing the principle of measuring the half-width value, and FIG. 6 is a waveform diagram showing the cause of peak shift. Explanation of symbols of main parts 1... Microprocessor 2... Read/Write IC 3... Low pass filter 4... Equalizer 7... Half-width detection circuit Fig. 3-1■

Claims (2)

[Claims] (1) A magnetic disk medium on which a solitary wave signal for half-width measurement is recorded. (2) comprising a magnetic disk medium on which a solitary wave signal for half-width measurement is recorded, a reading means for reading out the solitary wave signal, and a means for measuring the half-width of the read solitary wave signal; A magnetic disk device characterized in that a peak shift of a read pulse of the magnetic disk medium is compensated according to the value of the measured half-width.