JPH04368680A - Positioning device for magnetic head in magnetic disk device - Google Patents

Abstract

PURPOSE:To enhance positional precision by attaining the positional information of an excellent S/N by using the differential signal of a first and a second positional signal with a quadrature phase difference obtained based on servo information recorded previously to a servo track. CONSTITUTION:A regenerating signal from a magnetic head 1 to regenerate the servo information recorded previously to the exclusive servo track for positioning is supplied to a pulse generator 2 and signal detectors 3-6. By the circuits 3-6 receiving sampling pulses Ps1-4 generated with the circuit 2 based on the synchronizing signal in the regenerating signal, output signals Sa-Sd attained by sampling the regenerating signal are operated with subtractors 7, 8. The positional signals N, Q with the phase difference of 90 degree attained by this operation are changed over with a switch 9 by the switch control signal of a supply terminal 10, the position of the head 1 is controlled so that the output of a computing element 11 is zero. Thus, the positional information of the excellent S/N is attained and the positional precision is enhanced.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head positioning device in a magnetic disk drive for positioning a magnetic head.

0002

2. Description of the Related Art In magnetic disk drives, as a means for positioning a magnetic head on a specific track, that is, as a means for positioning the magnetic head, a servo is used that has servo information exclusively for positioning written on the magnetic disk surface in advance. By providing a track and positioning the servo information magnetic head on a predetermined track based on the servo information reproduced by the servo information magnetic head, the servo information magnetic head described above can be used. It is common practice to ensure that operative magnetic data heads are positioned over predetermined data tracks. As one of the above-described magnetic head positioning means in a magnetic head device, a first magnetic head having a phase difference of 90 degrees is used based on servo information pre-recorded on a servo track for positioning the magnetic head. , a magnetic disk device that generates a second position signal and thereby performs a positioning operation of a magnetic head,
For example, JP-A-52-4209, JP-A-54-11
9215, JP-A-55-87350, and other publications.

0003

[Problems to be Solved by the Invention] In recent years, as various recording media have become capable of recording at high recording densities, magnetic disk devices have also become capable of recording at high recording densities. However, as the recording density improves, the track pitch becomes narrower, which causes the S/N of servo information reproduced from the servo information magnetic head to deteriorate, resulting in a decrease in positioning accuracy. became a problem, and a solution was sought.

0004

[Means for Solving the Problems] The present invention uses first and second position signals having a phase difference of 90 degrees obtained based on servo information pre-recorded on a servo track for positioning a magnetic head. A magnetic head positioning device in a magnetic disk device configured to perform a head positioning operation, in which the magnetic head is positioned using a difference signal between the first and second position signals. I will provide a.

[0005]

[Operation] A difference signal between first and second position signals having a phase difference of 90 degrees obtained based on servo information previously recorded on a servo track for positioning the magnetic head, that is,
Since the magnetic head is positioned using both the first and second position signals, the magnetic head can be positioned using position information with a good S/N ratio, thus improving positioning accuracy. can be done.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific details of a magnetic head positioning device in a magnetic disk drive according to the present invention will be explained in detail below with reference to the accompanying drawings. 1 and 2 are block diagrams showing the schematic configuration of the magnetic head positioning device in the magnetic disk device of the present invention, and FIGS. 3 to 5 are block diagrams showing the operation of the magnetic head positioning device in the magnetic disk device of the present invention. FIG. In FIGS. 1 and 2, reference numeral 1 denotes a magnetic head for servo information. The servo information is reproduced from the servo information and supplied to the pulse generation circuit 2 and signal detection circuits 3 to 6. The magnetization pattern of servo information recorded on the servo surface of the magnetic disk that is the target of reproduction by the magnetic head 1 for servo information described above is obtained by reproducing the magnetization pattern by the magnetic head 1 for servo information. From the servo information, 9
Any magnetization pattern may be used as long as it provides first and second position signals having a phase difference of 0 degrees.

FIG. 3(a) is a diagram showing an example of a magnetization pattern recorded on the servo surface of a magnetic disk. In FIG. 3(a), Tr1, Tr2, T
r3... indicates sequential servo tracks, and the direction of the arrow shown near the center of each servo track indicates the direction of magnetization in each part. a, b, c, d...h are the magnetic head 1 for servo information in a state where each reproduction signal shown in FIGS. 4(a) to (h) is obtained from the magnetic head 1 for servo information, respectively. It shows the center position of. Also, AA', BB', CC shown in Fig. 3(a) and Fig. 4
Symbols such as ', DD', etc. indicate respective spatial positions such as AA', BB', CC', and DD' shown in (a) of FIG. 3, and AA' shown in FIG. 4. , BB', CC', DD'
This is to show that the respective temporal positions of , etc. correspond to each other. Note that the magnetization pattern shown in FIG. 3A is a magnetization pattern well known as a two-phase modified tie-bit pattern. Then, the waveform of the signal reproduced by the magnetic head 1 for servo information from the servo surface of the magnetic disk on which the magnetization pattern according to the two-phase modified tie-bit pattern shown in FIG. 3(a) is recorded and formed. 4(a) and (b) as the center position of the magnetic head 1 for servo information changes in the radial direction of the magnetic disk as shown in a, b, c to h in FIG. 3(a). , (c) to (h), respectively, is well known.

The magnetic head positioning device in the magnetic disk drive of the present invention shown in FIGS. 1 and 2 has a magnetization pattern based on servo information dedicated to positioning as shown in FIG. 3(a). The reproduction signal from the servo information magnetic head 1 which reproduces servo information from the servo surface of the magnetic disk is supplied to the pulse generation circuit 2 and the signal detection circuits 3 to 6 as described above. The pulse generating circuit 2 generates a signal as shown in FIG.
Sampling pulses Ps1 to Ps4 are generated at respective time positions corresponding to the time positions of drawing numbers AA', BB', CC', DD', etc. in FIG. The sampling pulse Ps1 generated at each time position is supplied to the signal detection circuit 3, and the sampling pulse Ps2 generated at each time position corresponding to the time position indicated by the reference symbol BB' in FIG. 4 is supplied to the signal detection circuit 4. Furthermore, the sampling pulse Ps3 generated at each time position corresponding to the time position indicated by the drawing symbol CC' in FIG. The sampling pulse Ps4 generated at each time position is supplied to the signal detection circuit 6.

[0009] Each of the signal detection circuits 3 to 6 described above samples the signal at the time when the sampling pulses Ps1 to Ps4 supplied from the pulse generation circuit 2 described above is supplied, and detects the sampled signal. output signal S
a, Sb, Sc, Sd {see (a) to (d) in FIG. 5}. The signal Sa output from the signal detection circuit 3 described above is supplied to the subtractor 7 as a minuend signal, and the signal Sb output from the signal detection circuit 4 described above is supplied to the subtractor 7 as a subtraction signal, and further, The signal Sc output from the signal detection circuit 5 described above is supplied to the subtracter 8 as a minuend signal, and furthermore, the signal Sd output from the signal detection circuit 6 described above is supplied to the subtracter 8 as a subtraction signal. Therefore, the aforementioned subtracter 7 outputs a signal (Sa-Sb) as shown in FIG. 5(e), and the aforementioned subtracter 8 outputs the signal (Sa-Sb) as shown in FIG. 5(f). A signal (Sc-Sd) is output. The symbols a, b, c, etc. shown at the bottom of FIG. 5(f) correspond to the symbols a, b, c, etc. shown in FIG. 3(a). The signal N=(Sa−Sb) output from the subtracter 7 and the signal Q=(Sa−Sb) output from the subtracter 8.
(Sc-Sd) are signals having a phase difference of 90 degrees, as is clear from FIGS. 5(e) and 5(f).

The magnetic head positioning device in the magnetic disk drive of the present invention shown in FIG. 1 is an embodiment in which signal processing is performed in the state of analog signals, and A magnetic head positioning device in a disk drive is an embodiment in which signal processing is performed in the form of digital signals. First, in the embodiment shown in FIG. Q is supplied to the fixed contacts e2 and o1 of the changeover switch 9. The movable contacts v1 and v2 of the changeover switch 9 are switched between two fixed contacts in conjunction with a changeover control signal supplied from a control circuit (not shown) to a control signal supply terminal 10. That is, the movable contact v1 is switched to the fixed contact o1 side at odd-numbered track positions, and switched to the fixed contact e1 side at even-numbered track positions, and the movable contact v2 is switched to the fixed contact o2 side at odd-numbered track positions. At even-numbered track positions, the contact is switched to the fixed contact e2 side. The output signal from the movable contact v1 of the changeover switch 9 described above is supplied to the subtractor 11 as a minuend signal,
Further, the output signal from the movable contact v2 of the changeover switch 9 is supplied to the subtracter 11 as a subtraction signal. When the target track of the target track is an even-numbered track, the signal outputted from the subtracter 11 to the output terminal 12 is (N-Q), and When the current track is an odd-numbered track, the signal output from the subtracter 11 to the output terminal 12 is (Q-N), which is the signal output from the subtracter 11 to the output terminal 12. When is 0, the magnetic head 1 for servo information is in a state where it is correctly tracking the target track, as shown in FIG. 3(b).
Each point where the signal N and the signal Q have the same magnitude is a position where the magnetic head 1 for servo information is made to correctly track the target track.

Next, in the embodiment shown in FIG. 2, the output signal N from the subtracter 7 is converted into a digital signal by an analog-to-digital converter 13 and then supplied to an arithmetic unit (arithmetic circuit) 15. Further, the signal Q output from the subtracter 8 is converted into a digital signal by an analog-to-digital converter 14 and then supplied to an arithmetic unit (arithmetic circuit) 15. The arithmetic unit 15 receives the number of tracks between the current position of the magnetic head 1 for servo information and the track to be on-track, and the current position of the magnetic head 1 for servo information from a control circuit (not shown). Information such as whether it is an odd-numbered track or an even-numbered track is given, and if the track targeted for on-track is an even-numbered track, the arithmetic unit 15 calculates (N-Q).
The calculation is performed and the result is output to the output terminal 16. Also, if the track targeted for on-track is an odd numbered track, the calculation (Q-N) is performed in the calculation unit 15 and the result is output. is output to the output terminal 16. When the signal outputted to the output terminal 16 is in the state of 0, the magnetic head 1 for servo information is brought into a state in which it is correctly tracking the target track. Each point where N and signal Q have the same magnitude is a position where the magnetic head 1 for servo information is made to correctly track the target track.

0012

Effects of the Invention As is clear from the above detailed explanation, the magnetic head positioning device in the magnetic disk drive of the present invention operates based on servo information pre-recorded on the servo track for positioning the magnetic head. The magnetic head is positioned using the difference signal between the obtained first and second position signals N and Q having a phase difference of 90 degrees, that is, both the first and second position signals N and Q. As a result, in a conventional magnetic head positioning device for a magnetic disk drive, the first and second magnetic head positions having a phase difference of 90 degrees obtained based on servo information pre-recorded on a servo track for positioning the magnetic head. 2 position signals N, Q
Compared to the case where the magnetic head is positioned using only one of the position signals, the magnetic head can be positioned using position information with a good S/N ratio. This makes it possible to improve positioning accuracy.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a schematic configuration of a magnetic head positioning device in a magnetic disk device of the present invention.

FIG. 2 is a block diagram showing a schematic configuration of a magnetic head positioning device in a magnetic disk device of the present invention.

FIG. 3 is a diagram for explaining the operation of the magnetic head positioning device in the magnetic disk device of the present invention.

FIG. 4 is a diagram for explaining the operation of the magnetic head positioning device in the magnetic disk device of the present invention.

FIG. 5 is a diagram for explaining the operation of the magnetic head positioning device in the magnetic disk device of the present invention.

[Explanation of symbols]

1...Magnetic head for servo information, 2...Pulse generation circuit,
3 to 6... Signal detection circuit, 7, 8, 11... Subtractor, 9... Changeover switch, 13, 14... Analog-to-digital converter, 1
5... Arithmetic unit,

Claims (1)

[Claims] [Claim 1] 90 points obtained based on servo information recorded in advance on a servo track for positioning the magnetic head.
In a magnetic disk drive that performs a positioning operation of a magnetic head using first and second position signals having a phase difference of 100 degrees, a difference signal between the first and second position signals is used to position the magnetic head. A magnetic head positioning device for a magnetic disk device which performs positioning of a magnetic head.