JPH01124165A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To correctly position a servohead to an aiming track always with the positional signal of high accuracy being obtd. by executing a correction so as to make the positional signal a fixed amplitude by comparing the positional signal detected by the servohead with the reference positional signal of a fixed amplitude. CONSTITUTION:This device is equipped with the reference positional signal generating circuit 9 generating the reference positional signal of its amplitude being certain, the comparison circuit P3 comparing the positional signal detected by a servohead with a reference positional signal and the positional signal correction circuit 10 making the output signal of this comparison circuit in a fixed amplitude. The reference positional signal generating circuit 9 outputs the reference positional signal of a certain amplitude, the comparison circuit P3 compares the reference positional signal with the positional signal detected by the servohead and the positional signal correction circuit 10 corrects the output signal of the comparison circuit in a fixed amplitude. The servohead can thus be correctly positioned at all times.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic disk device used in electronic computers or peripheral terminal equipment thereof.

C. Prior Art] Figure 4 shows, for example, Research and Practical Application Report Vol. 28, No. 10 (19
FIG. 79) is a block diagram of the head positioning control system shown in Peripheral Circuit for 800 MB Magnetic Disk Device, pages 2265 to 2269. The output signal is input to the adder circuit P2 which inputs the position signal detected by the servo head (not shown) and the signal of the target track position, and the output signal of the position signal reproducing circuit 1 which reproduces the position signal is transmitted to the servo head. The signal is input to a speed detection circuit 2 that reproduces moving speed information and a position error detection circuit 5 that detects the difference between the target trunk position and the head position. The output signal of the power amplifier 7 that supplies current to the positioning mechanism of the servo head is input to the speed detection circuit 2, and the output signal of the speed detection circuit 2 is input to the addition circuit P1. An output signal from a speed reference generation circuit 3 that provides a profile of the moving speed of the servo head is input to the addition circuit P1. The output signal of the adder circuit P1 is input to a speed error detection circuit 4 that detects the difference between the speed reference signal generated by the speed reference generation circuit 3 and the actual moving speed detected by the speed detection circuit 2. . Both the output signal of the speed error detection circuit 4 and the output signal of the position error detection circuit 5 are input to a mode switching control circuit 6 which selects either the speed error or the position error. The output signal of the mode switching control circuit 6 is input to the power amplifier 7, and the output signal of the power amplifier 7 is applied to a voice coil motor 8, which is a positioning mechanism for positioning the servo head at a target trunk position. A position signal detected by the servo head driven by the voice coil motor 8 is input to the adder circuit P2.

The operation of this head positioning control system will be explained.

As shown in Figure 5 (c), 2
Different types of servo patterns ODD and EVEN are recorded, and the servo patterns are read out by a servo head (not shown). When the servo head is at each of the positions (a), (b), and (C) in FIG. 5(B), the signal waveform read by the servo head is (a').

(b') and (c'), and the signal waveform output by the position signal reproducing circuit 1 at that time is shown in FIG. 5(C) (a'
), (b"), (c"). And speed detection circuit 2
The moving speed of the servo head is detected by detecting the magnitude of the time differential of the position signal. The difference between the detected moving speed and the reference speed given from the speed reference circuit 3 is detected by the speed error detection circuit 4, and the difference is detected in the speed control mode until half a track before the target track, and thereafter in the position tracking mode. After the speed difference signal, a position detection signal is input to the power amplifier 7 to drive the voice coil motor 8 and move the servo head to the target track position.

Note that the position signal reproduction circuit 1 reproduces the position signal at the maximum amplitude (2) of the signal without the influence of crosstalk in the read waveform of the signal shown in FIG. 5(B) when the servo head reads out the servo pattern. and the maximum amplitude (1) of the signal affected by crosstalk, it is calculated from the following formula.

(K is a coefficient) From this calculation result, if there is a lot of crosstalk, see Figure 5 (C
), and when the crosstalk is small, it changes as shown by the broken line. Moreover, when there is no influence of crosstalk, the change is as shown by the solid line.

[Problem that the invention seeks to solve]

In conventional magnetic disk drives equipped with the above-mentioned head positioning control system, the waveform of the signal obtained by the servo head reading the servo pattern differs between the inner and outer circumferential sides of the magnetic disk due to the influence of crosstalk. The amplitude of the position signal also changes accordingly. Therefore, there is a problem in that the speed signal, which is the time differential of the position signal, changes and an erroneous signal is input to the power amplifier, making it impossible to accurately position the servo head on the target track.

In view of the above-mentioned problems, the present invention has been developed so that even if distortion occurs in the read waveform of the signal from which the servo head successively prints the servo pattern,
An object of the present invention is to provide a magnetic disk device that can move a servo head to a target track position.

[Means for solving problems]

A magnetic disk drive according to the present invention includes a reference position signal generation circuit that generates a reference position signal having a constant amplitude, a comparison circuit that compares a position signal detected by a servo head with the reference position signal, and this comparison circuit. The configuration includes a position signal correction circuit that makes the output signal of a constant amplitude.

[Effect]

The reference position signal generation circuit outputs a reference position signal of constant amplitude. The comparison circuit compares the reference position signal and the position signal detected by the servo head. The position signal correction circuit corrects the output signal of the comparison circuit to a constant amplitude. Therefore, the servo head can always be accurately positioned.

〔Example〕

The present invention will be described in detail below with reference to drawings showing embodiments thereof.

FIG. 1 is a block diagram of a head positioning control system of a magnetic disk device according to the present invention.

A position signal reproducing circuit 1 which receives an output signal from an adder circuit P2 which receives a position signal detected by a servo head (not shown) and a target track position signal, and reproduces a position signal.
The output signal is input to a speed detection circuit 2 for reproducing a moving speed signal for the servo 7, a position error detection circuit 5 for detecting the difference between the target track position and the head position, and an addition circuit P3.

The output signal of the power amplifier 7 that supplies current to the positioning mechanism of the servo head is input to the speed detection circuit 2, and the output signal of the speed detection circuit 2 is input to the addition circuit P1. An output signal from a speed reference generation circuit 3 that provides a profile of the moving speed of the servo head is input to the addition circuit P1. The output signal of the adder circuit P1 is input to a speed error detection circuit 4 which detects the difference between the speed reference signal generated by the speed reference generation circuit 3 and the actual moving speed detected by the speed detection circuit 2. Both the output signal of the speed error detection circuit 4 and the output signal of the position error detection circuit 5 are input to a mode switching control circuit 6 which selects either the speed error or the position error.

The output signal of the mode switching control circuit 6 is the power amplifier 7.
The output signal of the power amplifier 7 is applied to a voice coil motor 8, which is a positioning mechanism for positioning the servo head at a target track position.

The position signal of the servo head driven by the voice coil motor 8 is input to an adder circuit P2 to which a trunk detection signal that detects the track position is input. The output signal of this adder circuit P2 is input to the position signal reproducing circuit 1. The adder circuit P3, which receives the output signal of the position signal reproducing circuit 1, receives the output signal of the reference position signal generating circuit 9, which generates a reference position signal of constant amplitude. The output signal of the adder circuit P3 is input to the position signal correction circuit 10.

The position signal correction circuit IO detects the difference between the position signal reproduced by the position signal reproduction circuit 1 and the reference position signal generated by the reference position signal generation circuit 9, corrects the position signal, and generates a corrected output signal. is given to the position signal reproducing circuit 1.

The position signal correction circuit 10 is constructed as shown in FIG. A position signal to be corrected is provided to a full-wave rectifier circuit 11 and an amplifier circuit 14 having an automatic gain control function. The output signal of the full-wave rectifier circuit 11 is given to a peak hold circuit 12, and each output signal of the peak hold circuit 12 and a reference position signal generation circuit 9 that generates a reference position signal of constant amplitude is given to a comparison circuit 13. . The output signal of the comparator circuit 13 is given to the amplification circuit 14, and the amplification circuit 1
The corrected position signal is output from the output side of No. 4.

Now, the control operation of the head positioning control system of the magnetic disk device configured as described above will be explained with reference to FIGS. 1 to 3. A servo head (not shown) reads out a servo pattern stored on a servo disk. The position signal reproducing circuit 1 reproduces the position signal based on the read waveform of the read signal. Then, the reference position signal of constant amplitude generated by the reference position signal generation circuit 9 and the position signal reproduced by the position signal reproduction circuit 1 are inputted to the adder circuit P3 and inputted to the position signal correction circuit 10. The position signal correction circuit 10 corrects the position signal so that its amplitude is constant, and provides the position signal reproducing circuit 1 with a position signal in which the influence of crosstalk on the position signal is eliminated. The speed detection circuit 2 performs time differentiation of the position signal to detect the moving speed of the servo head.

Then, the speed error detection circuit 4 detects the difference between the detected moving speed and the reference speed given from the speed reference circuit 3, and inputs the detected speed difference signal to the power amplifier 7 via the mode switching control circuit 6. Drive the voice coil motor 8 to drive half a track short of the target track in speed control mode.
Thereafter, the mode is switched by the mode switching control circuit 6, and the voice coil motor 8 is driven in the position following mode to move the servo head to the target track position.

By the way, by providing the position signal correction circuit 10, the position signal S20 shown in FIG. The full-wave rectified signal S21 shown in FIG. 3(b) is obtained.The peak hold circuit 12 holds the peak value of the full-wave rectified signal S21 to obtain a peak hold signal S22. Thereafter, the comparison circuit 13 detects the difference between the constant amplitude reference position signal S23 generated by the reference position signal generation circuit 9 and the peak hold signal S22,
The detection result is input to the amplifier circuit 14, and the amplitude of the reproduced position signal 520 is corrected to be the amplitude of the reference position signal S23, and the position signal S24 after correction to a constant amplitude is shown in FIG. 3(C). get. This position signal S24 is input from the position signal correction circuit 10 to the position signal reproducing circuit 1, and the servo head is driven as described above. Even if the position signal detected by the servo head and reproduced is affected by crosstalk, the signal that drives the servo head to the target track position will not be affected by crosstalk and will always be accurate. This enables positioning of the servo head.

〔Effect of the invention〕

As detailed above, the present invention compares the position signal affected by crosstalk detected by the servo head with a reference position signal of constant amplitude, and performs correction so that the position signal has a constant amplitude. , a highly accurate position signal can be obtained, and the servo head can always be accurately positioned on the target trunk.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a bed positioning control system of a magnetic disk drive according to the present invention, FIG. 2 is a block diagram of a position signal correction circuit, and FIG. 3 is a waveform diagram of a position signal indicating a correction state.
FIG. 4 is a block diagram of a conventional head positioning control system, and FIG. 5 is a waveform diagram of a servo pattern, a signal waveform read from the servo pattern, and a position signal affected by crosstalk. 1...Position signal regeneration circuit 2...Speed detection circuit 3.
・・Speed reference generation circuit 4・・Speed error detection circuit 5・
...Position error detection circuit 6...Mode switching control circuit 7
...Power amplifier 8...Voice coil motor 9.
...Reference position signal generation circuit 10...Position signal correction circuit Pi, P2. P3...addition circuit Note that in the drawings, the same reference numerals indicate the same or corresponding parts. Agent Masuo Oiwa】0 Iffl2! ``I word'' No.--Q studies 10E Yoa arithmetic
1st one! No. 21ii] Complaint 3, 4'EJ, Suspension 5, Amended Procedures (Voluntary), Showa, Month, Date, Department Director-General. 1. Indication of the incident Patent Application No. 1981-281615 2.
Name of the invention: Magnetic disk device 3, relationship to the case of the person making the amendment Patent applicant address: 2-2-3 Marunouchi, Chiyoda-ku, Tokyo Name (601) Mitsubishi Electric Corporation Representative Moriya Shiki 4, Agent Address Mitsubishi Electric Corporation, 2-2-3 Marunouchi, Chiyoda-ku, Tokyo Name (7375) Masuo Oiwa, patent attorney /゛- (Contact information 0
3 (213) 3421 Patent Division) (□ ・5, "Detailed Description of the Invention" column 6 of the specification to be amended, "Detailed Description of the Invention" column (1) Description of the description of the contents of the amendment ``Figure 5 (B)'' in lines 14 to 15 of page 3 is corrected to ``Figure 5 (A).'' (2) In line 16 of page 3 of the specification, ``Figure 5 (B)'' is corrected to ``Figure 5 (A)''. Next to "The signal waveform is", add "as shown in Figure 5 (B)". (3) In the 12th line of page 10 of the specification, "Aftermath rectifier circuit 11" is added.
" has been corrected to read "full-wave rectifier circuit 11."

Claims (1)

[Claims] 1. In a magnetic disk device that detects a position signal of a magnetic disk by a magnetic head, detects speed from the position signal, and positions the magnetic head at a target position, a reference position signal of constant amplitude is generated. a reference position signal generation circuit that compares the reference position signal and the position signal, and a position signal correction circuit that makes the position signal have a constant amplitude by the comparison circuit. magnetic disk device.