JPH03144977A - Disk eccentricity compensating device - Google Patents

Abstract

PURPOSE:To always output the correcting signal of an exact phase and amplitude by comparing an eccentricity correcting signal from a correcting amount generator with a position signal from a position signal demodulator and correcting an eccentricity correcting amount based on the result of this comparison. CONSTITUTION:A voice coil motor 3 moves a head 2. A timing identifier 4 identifies a phase signal in a circumferential direction from a servo surface 1. A position signal demodulator 5 demodulates a signal showing the position of the head 2 in a radial direction. A correcting amount generator 6 generates the correcting signal in this positions signal synchronously with the timing signal of the identifier 4. A compensator 7 compensates the position signal adding the correcting amount from this generator 6. Thus, the eccentricity correcting signal from the generator 6 is compared with the position signal form the demodulator 5 by a comparing means 8. Based on the comparing signal of this means 8, an arithmetic circuit 9 corrects the eccentricity correcting amount to be generated by the generator 6.

Description

[Detailed Description of the Invention] [Summary] This invention relates to a disk eccentricity compensator, in particular, a recording disk containing servo information, a head for writing and reading data on the recording disk, a voice coil motor for moving the head, and a recording disk that includes servo information. a timing discriminator that identifies a phase signal in the circumferential direction from the head; a position No. 48 demodulator that demodulates a signal indicating the position of the head in the diametrical direction; and a correction amount generator that generates the above-mentioned eccentricity correction signal. A compensator that compensates for the eccentricity correction signal added with the correction amount from the correction amount generator is provided, and the rotation center of the recording disk at the time of input and the rotation center of the recording disk at the time of playback are eccentric. The present invention relates to a disk eccentricity compensator that controls the position of a read head during playback in response to disk eccentricity using the read eccentricity correction signal via a compensator, and the object is to enable more precise head position control. a comparison means for comparing the eccentricity correction signal from the correction amount generator and the eccentricity correction signal from the eccentricity correction signal demodulator, and an eccentricity correction amount generated by the correction amount generator based on the comparison result of the comparison means. and a calculation means for correcting.

(Industrial Application Field) The present invention relates to a disk eccentricity compensator, and in particular, it has a recording disk including servo information, and the center of rotation of the recording disk at the time of input and the center of rotation of the recording disk at the time of reproduction. The present invention relates to a disk eccentricity compensating device that controls the position of a recording disk using an eccentricity correction signal read by a read head corresponding to the disk eccentricity through a compensator when reproducing a recording disk whose disk is eccentric.

(Prior Art) Generally, a magnetic disk drive is provided with a servo surface, and this servo surface is read by a servo head to control the position of the head. By the way, in such a magnetic disk device, when recording servo information and when reading the servo information, the rotating shaft of the magnetic disk causes precession due to reasons such as rattling of the disk bearing.
As shown in FIG. 3, since the center of rotation of the disk during writing and the center of rotation during reading are shifted, the head is moved in accordance with this shift. To control such a head, fine control is performed according to information on the servo surface.

There is a disk eccentricity compensator that performs such fine control as shown in FIG. In the figure, 10 is a servo surface of a magnetic disk device, 11 is a magnetic head that reads servo information on the servo surface, 12 is a voice coil motor that moves this magnetic head in the diametrical direction, and 13 is a servo read by the magnetic head 11. Timing discriminator that identifies the circumferential phase (timing) of a servo surface from information, 1
4 is an eccentricity correction signal demodulator for demodulating the eccentricity correction signal in the diametrical direction of the magnetic herad 11; 15 is an eccentricity correction signal demodulator 14;
16 is a low-pass filter for removing high-frequency noise, and 17 is a PID (proportional, integral, differential) of the signal that has passed through this low-pass filter 16.
18 is a power amplifier, 19 is a storage circuit that generates a correction signal based on the timing signal of the timing discriminator 13, and 20 is a correction amount that generates an actual correction signal based on the signal from the storage circuit 19. generator, 21
is a digital-to-analog converter (D/A) that converts the compensation amount generated by a digital signal into analog data.
It shows. In this example, the functions of the memory circuit and the correction amount generator can be realized by a single processor (encircled by a broken line in FIG. 5).

According to this example, as shown in FIG. 4, a correction signal corresponding to the amount of eccentricity is input to the voice coil motor in accordance with the timing generated by the timing discriminator 13 to follow the deviation of the recording track due to eccentricity. The magnetic head can be moved.

[Problem to be solved by the invention]

Incidentally, in recent years, the width of recording tracks has become narrower due to improvements in recording density, and as a result, the position of the head must be controlled more precisely.

However, in the conventional disk eccentricity compensator described above, eccentricity compensation is performed by adding the actual amount of eccentricity to the eccentricity correction signal from the eccentricity correction signal demodulator. , as shown in FIG. 6, the phase of the summed compensation signal deviates from the phase of the ideal compensation signal, resulting in a problem that desired precise control cannot be performed.

Therefore, an object of the present invention is to provide a disk eccentricity compensating device that can perform more precise head position control.

(Means for solving the problems) In the present invention, the means for solving the above problems are as follows:
As shown in FIG. 1, there is a recording disk containing servo information, a head 2 for writing and reading data on the recording disk, a voice coil motor 3 for moving the head 2, and a circumference from the servo surface 1 to the head 2 for reading and writing data to and from the recording disk. a timing discriminator 4 for identifying a phase signal in the direction; an eccentricity correction signal demodulator 5 for demodulating a signal indicating the position of the head in the radial direction; a correction amount generator 6 that generates a correction signal;
A compensator 7 that compensates for the eccentricity correction signal added with the correction amount from the correction amount generator 6 is arranged so that the center of rotation of the recording disk at the time of input is eccentric to the center of rotation of the recording disk at the time of playback. In a disk eccentricity compensation device that controls the position of the read head disk eccentricity in response to the read head disk eccentricity during reproduction of a recording disk, the eccentricity correction signal from the correction amount generator 6 and the eccentricity correction signal from the correction amount generator 6 are used. Comparison means 8 for comparing the eccentricity correction signal from the signal demodulator 5
and a calculation means 9 for correcting the eccentricity correction amount generated by the correction amount generator 6 based on the comparison result of the comparison means 8.

(Operation) According to the present invention, the comparison means compares the eccentricity correction signal from the correction amount generator and the eccentricity correction signal from the eccentricity correction signal demodulator, and the calculation means, based on the comparison result of the comparison means, Since the eccentricity correction amount generated by the correction amount generator is corrected, it is possible to always output a correction signal with accurate phase and amplitude.

〔Example〕

Embodiments of the disk eccentricity compensating device according to the present invention will be described below with reference to the drawings.

FIG. 2 shows an embodiment of the disk eccentricity compensating device according to the present invention. In this embodiment, the disk eccentricity compensator includes an analog-digital converter (A/D) 22 that converts a signal input to an operational amplifier from an analog signal to a digital signal in the conventional disk eccentricity compensator.
Other features include a comparator 23 that compares the correction amount generated by the correction amount generator with the digitalized signal, and an arithmetic circuit 24 that calculates the correct correction amount based on the comparison result of this comparator. Since the conventional disk eccentricity compensation device is also completely the same, the same members are given the same reference numerals and detailed explanation thereof will be omitted.

Next, the present invention will be explained in detail.

First, before actually using the magnetic disk drive, for example, when the power is turned on, the corrected signal digitized by the A/D is compared with the signal generated by the correction amount generator. This allows you to preset the actual correction signal (the signal that is driven by the signal that has passed through the filter, PID compensator, and power amplifier and is read by the head) and the output signal of the correction amount generator (the phase and amplitude that are considered correct). A certain signal) is compared to calculate the phase shift and amplitude shift of the actual correction signal.

Based on the difference between the phase and the amplitude, the calculation means calculates a correction value for correcting the corrected signal, and stores this value in the storage circuit. The storage circuit outputs this value based on the tying signal of the tying discriminator to correct the eccentricity correction signal.

In this embodiment, the correction signal for correcting the output of the eccentricity correction signal demodulation circuit is a correction signal calculated based on the actual correction value, and the phase and amplitude are correct after correction, and the voice coil is magnetically The head can be moved to the correct position, and the magnetic head of the magnetic disk device can be controlled more precisely.

(Effects of the Invention) As described above, according to the present invention, the disk eccentricity compensator includes a comparison means for comparing the eccentricity correction signal from the correction amount generator and the eccentricity correction signal from the eccentricity correction signal demodulator. , and a calculation means for correcting the eccentricity correction amount generated by the correction amount generator based on the comparison result of the comparison means. Therefore, in the present invention, a correction signal is attached to the output of the eccentricity correction signal demodulator. However, this correction signal is a correction signal calculated based on the actual eccentricity correction signal, and the magnitude of the phase difference amplitude is assumed to be correct, so the voice coil cannot move the magnetic head to the correct position. This has the effect that the magnetic head of the magnetic disk device can be controlled more precisely.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the principle of the present invention, FIG. 2 is a block diagram showing an embodiment of the disk eccentricity compensating device according to the present invention, FIG. 3 is a diagram showing disk eccentricity, and FIG. 4 is a diagram showing a correction signal. , FIG. 5 is a diagram showing a conventional disk eccentricity compensating device, and FIG. 6 is a diagram showing problems with the conventional disk eccentricity compensating device shown in FIG. 1... Servo surface 2... Head 3... Voice coil motor 4... Timing discriminator 5... Eccentricity correction signal demodulator 6... Correction amount generator 7... Compensator 8. ... Comparison means 9 ... Calculation means Honshushu no Hada, Can House ■ 4II So/) Departure No. 3Wl Zod strokes Positive a No. II 4 Prisoner

Claims (1)

[Claims] A recording disk containing servo information, a head (2) for writing and reading data on this recording disk, and a voice coil motor (3) for moving this head (2).
), a timing discriminator (4) that identifies a phase signal in the circumferential direction from the servo information, a position signal demodulator (5) that demodulates a signal indicating the position of the head in the diametrical direction, and a correction amount generator (6) that generates a correction signal in synchronization with the timing signal of the timing discriminator; and a compensator (7) that compensates for the position signal to which the correction amount from the correction amount generator (6) is added. When the rotation center of the recording disk at the time of input and the rotation center of the recording disk at the time of playback are eccentric, the read head is moved to a compensator ( 7
), a comparison means (8) for comparing the eccentricity correction signal from the correction amount generator (6) and the position signal from the position signal demodulator (5); A disk eccentricity compensating device comprising: a calculation means (9) for correcting the eccentricity correction amount generated by the correction amount generator (6) based on the comparison result of the comparison means (8). .