JPH06267216A - Magnetic recording device - Google Patents

Abstract

PURPOSE:To improve the quality of a reproduced signal by equalizing a reproduced signal read out from a magnetic head to a reproduced signal having fixed resolution in accordance with an equalizing quantity setting value. CONSTITUTION:A reproduced signal 6 read out from a magnetic head is inputted to an amplifier 1 and amplified to desired signal amplitude. An output of this amplifier 1 is sent to an equalizer 2, the equalizer 2 decides equalizing quantity in accordance with control quantity 11 from an equalizing quantity controller 5, and sends an output signal 12 to an output terminal and a signal separator 3. This separator outputs amplitude information 16 of a0 and amplitude information 17 in which a1 is added to a2 to the equalizing quantity controller 5. This controller 5 detects the difference between equalizing quantity setting values 9, 10 and amplitude information 16, 17 from the separator 3, and sends the difference to an equalizer 2 as equalizing control quantity 11. A timing generator 4 sends timing signals 13-15 to the circuit 3 by a sector pulse 8 and a clock 7. The reproduced signal 6 is equalized to a reproduced signal having fixed resolution by equalizing quantity setting values 9, 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording device having a magnetic head positioning mechanism.

[0002]

2. Description of the Related Art In magnetic disk devices, digital VTRs and the like, digital magnetic recording is used to record a binary digital signal on a recording medium as a magnetization reversal sequence. The signal reproduced from the magnetic head during reproduction is obtained as a superposition series of isolated waveforms corresponding to the magnetization reversal position. When the interval between the isolated waveforms becomes narrow, waveform interference occurs, which causes a phenomenon in which the signal amplitude decreases and the peak position shifts (hereinafter referred to as pattern peak shift). Both of these phenomena significantly deteriorate the performance of the device. FIG. 5A shows a magnetization pattern recorded on the medium. FIG. 5B shows a signal waveform read from the magnetic head, where the peak positions are t _s1 from the normal E and L positions due to the pattern peak shift.
A shift of t _s2 occurs. Further, the signal waveform has a signal amplitude that decreases in accordance with the amount of pattern shift. If this reproduced signal is supplied as it is to the signal processing system for data discrimination, the misreading rate of data is significantly deteriorated. Therefore, as a conventional measure, an equalizer such as cosine equalizer is provided to reduce the waveform interference. FIG. 5C is an output waveform when cosine equalization is applied to the signal waveform of FIG. 5B. The pattern peak shift is improved from FIG. 5 (c). It is also possible to realize transfer characteristics similar to cosine equalization by using active elements, and dedicated ICs are already on the market. The pattern peak shift in the previous period can be corrected by the equalizer, and the misreading rate of the device can be improved. However, if the characteristic of the equalizer is fixed, the characteristic of the head or the medium changes and the characteristic of the equalizer deviates from the optimum value. Therefore, it has been proposed that a pilot signal for detecting the electromagnetic conversion characteristics of the head and the medium is recorded on the medium in advance and the characteristic of the equalizer is changed according to the signal waveform of the pilot signal. However, if it is newly formed on the pilot signal medium, there arises a problem that the effective area of data is reduced and the recording capacity of the device is reduced.

[0003]

As described above, in the conventional case, in order to know the electromagnetic conversion characteristics of the head and the medium, a region for recording the pilot signal is required, so that the effective area of the medium is reduced. However, there is a problem that the recording capacity of the device decreases. Therefore, it is desired to reduce or eliminate the area occupied by pilot signals to increase the effective area.

According to the present invention, a servo pattern recorded in advance has a magnetization pattern including pilot signal information.
An object of the present invention is to provide a waveform equalizer capable of increasing the effective area of data.

[0005]

According to the present invention, a pilot signal for recording a magnetization pattern corresponding to two kinds of a low band and a high band is also used as the servo. The resolution corresponds to the signal amplitude ratio between the low frequency band and the high frequency band, and if the two types of signal amplitude information can be obtained, the equalization amount of the equalizer can be determined. The servo information of the present invention is the AG
The C signal is substituted for the low-frequency signal amplitude, and the signal amplitude of the position information is substituted for the high-frequency signal amplitude, so that the difference between the high-frequency signal amplitude and the low-frequency signal amplitude is always constant. It controls the quantity.

[0006]

According to the present invention, the servo information can include information on the resolution necessary to equalize the reproduced signal.
Therefore, the quality of the reproduced signal can be improved without reducing the effective area of the medium for recording data.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. When the frequency to be recorded on the medium is increased (the recording density is increased), the reproduced signal read out has a reduced amplitude due to waveform interference and an increased pattern peak shift.

FIG. 1 shows the relationship between the recording frequency and the reproduction signal amplitude. The parameter is the resolution, which is caused by the individual difference in the head / medium. Here, a0 is standardized to 1 in the low-frequency amplitude. In the figure, signal amplitude differences like e, f, and g occur at the recording frequency fm in the high range. This difference is caused by the difference in waveform interference. Waveform interference can be reduced by waveform equalization. For example, the signal amplitudes f and g can be matched with the signal amplitude e by the equalization amount. The main purpose of the present invention is to record frequencies fi and fm in FIG.
By using the information (pilot signal) for detecting the two types of signal amplitudes corresponding to (1) and the servo information, the area occupied by the pilot signal is eliminated.

FIG. 2 shows servo information and data areas.
FIG. 7A shows an index signal corresponding to one rotation of the spindle motor with the medium attached. FIG. 3B shows sector pulses obtained by equally dividing one track. Servo information is provided in each sector. In a magnetic disk device, data is handled in blocks of sector units. The servo information is written for each sector, and FIG. 7C shows the positional relationship between the servo area in which the servo information is written and the data area in which the data is written. Here, the servo area and the data area may be mixed. FIG. 3 is an enlarged view of the servo area. In FIG. 3A, the vertical direction is the track direction and the horizontal direction is the sector direction. Tracks are formed concentrically in the data area shown in FIG. When recording / reproducing data, the magnetic head is positioned at the center of the track as shown in the figure. In the AGC information of FIG. 3A, the recording frequency fi of FIG. 1 is recorded seamlessly in the track direction. In the position information of FIG. 3A, the magnetization pattern corresponding to the recording frequency fm of FIG. 1 is alternately recorded from the center of a track to the center of an adjacent track as shown in FIG. Further, the white background of the position information area is an erase area in which no magnetization pattern is formed. When the magnetic head is accurately positioned on an arbitrary track, the signal amplitude read from the magnetic head is as shown in FIG. In this figure (a), a0 is the amplitude of AGC information, a1 and a2 are the amplitudes of position information, and a3 is the signal amplitude of the data area. The positioning of the magnetic head is controlled so that the signal amplitudes a1 and a2 are equal. Here, the amplitudes a1 and a2 of the position information
Is a constant value regardless of the position of the magnetic head. The value corresponds to the amplitude of the recording frequency fm shown in FIG. As described above, by recording a specific recording frequency in the servo information, it is possible to detect the resolution of the reproduction signal, that is, the ratio of the reproduction signal amplitude in the low frequency band and the high frequency signal, from the information.

The operation of one embodiment will be described below with reference to the block diagram. FIG. 4 is a block diagram showing the circuit of the present invention. The reproduction signal 6 read from the magnetic head is connected to the amplifier 1 and amplified to a desired signal amplitude. The output of the amplifier 1 is connected to the equalizer 2. Equalizer 2
Determines the equalization amount of the reproduction signal from the amplifier 1 according to the control amount 11 from the equalization amount controller 5, and outputs the output signal 12 to the output terminal and the signal separator 3.

The signal separator 3 is controlled by the timing signals 13, 14, 15 sent from the timing generator 4 in FIG.
The signal amplitudes of a0, a1, and a2 in (b) are detected. The signal separator 3 outputs the amplitude information 16 of a0 and the amplitude information 17 of the sum of a1 and a2 to the equalization amount controller 5. on the other hand,
The equalization amount controller 5 receives the equalization amount set values 9 and 10.
The equalization amount setting values 9 and 10 are the recording frequency f shown in FIG.
It is a signal amplitude value of i and fm. The equalization amount controller 5 uses the equalization amount set values 9 and 10 and the amplitude information 1 from the signal separator 3.
The difference between 6 and 17 is detected, and the difference is sent to the equalizer 2 as the equalization control amount 11. The timing generator 4 uses the sector pulse 8 and the clock 7 to generate timing signals 13, 1
4 and 15 are sent to the signal separation circuit 3. Through the series of operations described above, the reproduction signal 6 read from the magnetic head is equalized into a reproduction signal having a certain resolution according to the equalization amount setting values 9 and 10. The present invention can improve the quality of a reproduced signal without adding information for equalization on the medium.

[0012]

According to the present invention, the servo information can include information on the resolution necessary for equalizing the reproduction signal. Therefore, it is possible to improve the quality of the reproduced signal without reducing the effective area of the medium for recording the data.

[Brief description of drawings]

FIG. 1 is a diagram showing the resolution (amplitude characteristic) of magnetic recording characteristics.

FIG. 2 is a diagram showing a positional relationship between a servo area and a data area occupying one sector.

FIG. 3 is a diagram showing a servo pattern and a signal amplitude of servo information read by a magnetic head.

FIG. 4 is a block diagram showing an embodiment of the present invention.

FIG. 5 is a diagram for explaining a conventional example.

[Explanation of symbols]

1 ... Amplifier 2 ... Equalizer 3 ... Signal separator 4 ... Timing generator 5 ... Equalization amount controller 6 ... Reproduction signal 7 ... Clock 8 ... Sector pulse 9, 10 ... Equalization amount set value
11 ... Equalization control amount 12 ... Output signal 13, 14, 15
... Timing signals 16, 17 ... Amplitude information

Claims (1)

[Claims] 1. A magnetic recording apparatus for recording servo information in a part of each sector area in advance and positioning a magnetic head according to the servo information, and recording two or more types of repetitive patterns in the servo information. And means for positioning the magnetic head based on the amplitude information of the repeating pattern, and means for changing the equalization amount of the reproducing signal obtained from the magnetic head according to the difference in the reproducing signal amplitude of the repeating pattern. A magnetic recording device characterized by: