JPH03113877A - Magnetic head positioning system for magnetic recorder - Google Patents

Abstract

PURPOSE:To obtain the head positioning system which is not influenced by a rotational fluctuation, etc., of a spindle motor by detecting and calculating a peak of an alternating servo-signal, and varying a threshold voltage depending on the number of peaks of the alternating servo-signal. CONSTITUTION:A peak detecting circuit 12 for detecting a peak of negative polarity, etc., of an alternating servo-signal is provided, and whenever the peak is detected by the peak detecting circuit 12, it is counted by a microcomputer 4, and a threshold voltage whose magnitude becomes large or small in accordance with its counting is generated by a threshold voltage generating circuit 10. Accordingly, even if the peak detection time point is shifted due to a fluctuation of a period of the alternating servo-signal, a variation time point of magnitude of the threshold voltage is also shifted in accordance therewith, and the number of pulses of a digital servo-signal obtained by comparing them is not varied. In such a way, the head positioning system which is not influenced by a fluctuation of a period of a read-out alternating servo-signal caused by a rotational fluctuation, etc., of a spindle motor can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic head positioning method for a magnetic recording device that positions a magnetic head using a servo signal read from a magnetic disk disk.

[Prior Art] Magnetic head positioning methods for magnetic recording devices are broadly classified into servo surface servo methods and data surface servo methods, depending on the method used for recording servo signals on a magnetic disk disk. The data surface servo method can be further divided into a method in which a servo signal is processed in an analog manner to control a magnetic head, and a method in which a servo signal is processed in a digital manner to control a magnetic head.

Figures 3 to 7 are, for example, Japanese Patent Application Laid-Open No. 63-11398.
7 shows a conventional magnetic head positioning system for a magnetic recording device using a data surface servo system in which a servo signal is digitally processed to control a magnetic head, and FIG. 3 is a schematic configuration diagram thereof. 5 is an enlarged view showing the state of the servo area where servo signals are recorded on the surface of the magnetic disk, and FIGS. 6 and 7 are diagrams showing the state of the surface of the magnetic disk. It is a signal waveform diagram for explaining its operation. In the figure, (1) is a magnetic disk disk surface (hereinafter simply referred to as disk surface), (2) is a data area where recording/reproduction data is recorded, (3) is a servo area where servo signals are recorded, (4) A microcomputer (hereinafter referred to as a microcomputer) as a control means;
(5) is a magnetic head (hereinafter simply referred to as a head), (6
) is a positioning mechanism that supports the head (5), (7) is a positioning mechanism drive circuit that drives the positioning mechanism (6), (
8) is a read/write circuit, (9) is a servo signal detection circuit that detects and outputs only a servo signal among read signals, (10) is a threshold voltage generation circuit, and (11) is a voltage comparison circuit. As is clear from FIGS. 4 and 5, data areas (2) and servo areas (3) are arranged alternately in the circumferential direction Cr on one disk surface (1), and the servo areas (3) Patterns A and B of magnetization reversal over adjacent tracks are recorded alternately. FIG. 6 shows an analog alternating servo signal which is the output of the servo signal detection circuit (9) read from the servo area (3) by the magnetic head (5), and (a) shows that the head (5) is tracking the track. (b) shows signals when the head is tracking accurately (on-track) and when the head is off-track (off-track), respectively. Figure 7 shows on-track (a) in Figure 6.
The digital servo signals which are the outputs of the voltage comparator circuit (10) in each case of (b) and off-track are shown.

Next, we will explain its operation. When the head (5) is accurately following the track, that is, when it is on track, the alternating servo signal read out from the servo area (3) by the head (5) becomes as shown in FIG. 6(a), and is divided into A pattern and B pattern. The amplitude will be equal. Since the threshold voltage from the threshold voltage generation circuit (10) changes over time as shown in the figure, these two signals are compared by the voltage comparison circuit (11), and when the alternating servo signal is higher than the threshold voltage, it is "H level" and low. By the way, “L
A digital servo signal with a pulse train output as shown in Fig. 7(a) with a level of
The A pattern and the B pattern are equal.

On the other hand, in the case of off-track where the head is off track, the alternating servo signal has different amplitudes for the A pattern and the B pattern as shown in FIG. 6(b). Therefore, the output of the voltage comparison circuit (11) is as shown in FIG. 7(b),
Digital servo signals with different numbers of pulses for the A pattern and the B pattern can be obtained. The more the head deviates from the track.

Since the magnitude of the alternating servo signal of the pattern on one side is further reduced, the number of pulses of the digital servo signal is further reduced. Therefore, the difference between the number of pulses of the digital servo signal of pattern A and that of pattern B represents the position signal. Then, the microcomputer (4) calculates the pulse number difference from these digital servo signals, controls the positioning mechanism drive circuit (7) accordingly, drives the positioning mechanism (6), and performs head positioning control using digital processing. will be carried out.

[Problems to be Solved by the Invention] In such a conventional head positioning control system, the time deviation of the servo signal due to rotational fluctuations caused by the spindle motor that rotates the disk disk has a large influence, making it difficult to perform accurate positioning. The problem was that it was not possible.

This will be explained below with reference to FIG. Figure 8 shows
The head (5) is following the track perfectly, but due to rotational fluctuations of the spindle motor, the period of the B pattern is now A.
As is clear from Figure 1, which is a signal waveform diagram showing the operation when the pattern period T is larger than the pattern period T, the amplitudes of the alternating servo signals of the A pattern and the B pattern are the same, but Relationship is A pattern and B
Since the patterns are not the same, the voltage comparison circuit (11)
The number of pulses of the digital servo signal output from the That is, the detection sensitivity changes due to rotational fluctuations, and as a result, accurate positioning control becomes impossible.

The present invention was made to solve these problems, and it is an object of the present invention to provide a magnetic head positioning method for a magnetic recording device that is not affected by periodic fluctuations in an alternating servo signal due to rotational fluctuations of a spindle motor, etc.

[Means for Solving the Problems] A magnetic head positioning method for a magnetic recording device according to the present invention detects and counts peaks of an alternating servo signal, and changes the magnitude of a threshold voltage according to the number of peaks. This is how it was done.

[Function] In the magnetic head positioning method of the magnetic recording device according to the present invention, the peaks of the alternating servo signal are inspected and counted, and the magnitude of the threshold voltage changes according to the number of peaks. Even if the peak detection time is shifted due to cycle fluctuations, the time at which the threshold voltage changes varies accordingly, and the number of pulses of the digital servo signal obtained by these comparisons does not change. Therefore, it is possible to obtain a head positioning method that is not affected by fluctuations in the period of the readout alternating servo signal due to rotational fluctuations of the spindle motor.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. 1st
2 shows an embodiment of the present invention, FIG. 1 is a schematic configuration diagram thereof, and FIG. 2 is a signal waveform diagram for explaining its operation. In the figure, (4) is a microcomputer, (5) is a head, (6) is a positioning mechanism, (7) is a positioning mechanism drive circuit, (8) is a read/write circuit, (9) is a servo signal detection circuit, ( 10) is a threshold voltage generation circuit, (11) is a voltage comparison circuit, which is the same as the conventional example, and (11) is a voltage comparison circuit.
12) is a peak detection circuit that detects the negative polarity peak (downward peak in the figure) of the alternating servo signal.
This is counted, and a threshold voltage whose magnitude increases according to the count is generated by a threshold voltage generation circuit (10).

Next, the operation will be explained with reference to FIG.

The figure shows a case where the alternating cycles of the alternating servo signals of the A pattern and the B pattern are different due to rotational fluctuations of the spindle motor, as in FIG. 8. The number of negative polarity peaks of the alternating servo signal detected by the peak detection circuit (12) is counted by the microcomputer (4). The threshold voltage generation circuit (10) generates a DC threshold voltage according to the number, and the voltage gradually increases by a predetermined value for each peak count.As is clear from Figure 1, the change in the threshold voltage is time dependent. Rather, it depends on the number of negative polarity peaks of the alternating servo signal, so even if the cycle of the alternating servo signal changes due to rotational fluctuations of the spindle motor, r:i will change accordingly.
! The timing of lightning voltage change also varies. Therefore, the voltage comparator circuit (
The temporal variations of both signal voltages compared by 11) match, and the number of digital servo signals generated from it does not vary. This makes it possible to eliminate the influence of time changes in the alternating servo signal.

In the above embodiments, the threshold voltage gradually increases according to the peak count, but it may also gradually decrease.

[Effects of the Invention] As described above, according to the present invention, the peaks of the alternating servo signal are detected and counted, and the magnitude of the threshold voltage is changed according to the number of peaks. This has the effect of providing a head positioning system for a magnetic recording device that allows digital processing to be performed without being affected by rotational fluctuations and improves reliability.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention, FIG. 2 is a signal waveform diagram for explaining its operation, and FIG. 3 is a general configuration diagram showing a head positioning system of a conventional magnetic recording device. Fourth
The figure shows the condition of the surface of the magnetic disk disk No. 5.
The figures are enlarged views showing the state of the servo area where servo signals are recorded on the surface of the magnetic disk, Figures 6 and 7.
The figure is a signal waveform diagram for explaining its operation, and FIG. 8 is a signal waveform diagram for explaining problems with the conventional head positioning system. In the figure, (4) is a microcomputer, (5) is a magnetic head,
(6) is a positioning mechanism, (7) is a positioning mechanism drive circuit, (8) is a read/write circuit, (9) is a servo signal detection circuit, (10) is a threshold voltage generation circuit, (11) is a voltage comparison circuit, (12) is a peak detection circuit. The same reference numerals in the figures indicate the same or corresponding parts. Figure 1 Figure 4 Figure 4 Alternative servo signal

Claims (1)

[Claims] Two predetermined patterns A and B are formed on a servo area provided on a concentric track formed on the surface of a magnetic disk disk.
is recorded, and from both patterns A and B, alternating servo signals are read out with the same amplitude when the magnetic head is on track and with different amplitudes when off track, and these read alternating servo signals are set to a predetermined threshold voltage that changes over time. By comparison, the read alternating servo signal is converted into a digital servo signal with a number of pulses corresponding to the amplitude, and the magnetic head is positioned according to the difference in the number of pulses of the digital servo signal according to both patterns A and B. In the magnetic head positioning method of the magnetic recording device, the peaks of the alternating servo signal are detected and counted, and the magnitude of the threshold voltage is changed according to the number of peaks. A magnetic head positioning method for magnetic recording devices.