JPH02123575A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To preform one cylinder seek for seeking from a present track position to an adjacent track position at high speed with small transient response only by a position control by changing a position signal slope in a slope selector circuit. CONSTITUTION:The slope selector 15 works in the position of a track 1 that only a signal 8 out of select signals 5-8 is turned on, and an analog switch 12 is turned on, and only a signal Q out of position signals N-Q is inverted by an operational amplifier 13 to be outputted as a selected position signal 21. The signal 21 is at the grounded level. When a track 2 is seeked, the signal is changed from 8 over to 5, and the analog switch from 12 over to 9 for their on-states respectively. The position signal is changed from Q4 to N1 and inverted to become the signal 21 with a negative voltage. The signal 21 is controlled in position in order to become at the grounded level via an integration circuit. By this constitution, one cylinder seek can be carried out at high speed with small transient response by the position control only.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic disk drive, and more particularly to seek operation control of a magnetic disk drive using a two-phase servo system.

[Conventional technology]

Conventionally, head positioning operations for this type of magnetic disk device include a track following operation to hold the head on a target track position, and a seek operation to move (seek) the head from the current track position to the target track position. In track following operation, one side of the disk stack is used as a servo surface, position information is written on the servo surface in advance, and a read-only servo head converts the position error information between the head and the track into a position signal. The servo circuit performs position control by feedback control of the position signal. In addition, in the seek operation, in order to make the speed signal indicating the actual speed of the head obtained by differentiating the position signal follow the speed reference signal of a predetermined profile, the difference between the speed signal and the speed reference signal is determined. The difference is used as a speed error signal to perform feedback control using a servo circuit.

At this time, even in the case of one-cylinder seek in which the current track position is sought from the adjacent track position, the speed control is used to accelerate and decelerate at the beginning of the seek to the target track position, and the position control starts from around 1/2 track before or before the target track position. Since switching control is performed, the access time for one cylinder seek can be shortened by making the deceleration profile of the speed reference signal steeper or by varying the timing of switching from speed control to position control. However, in the conventional method,
Shortening the access time has drawbacks such as increased transient response.

[Problem to be solved by the invention]

The problem to be solved by the present invention is to eliminate the drawbacks of the conventional positioning system as described above, and to seek from the current track position of the head to an adjacent track position.
In addition to shortening cylinder seek access time,
It is an object of the present invention to provide a magnetic disk device that reduces transient response after a seek and performs stable positioning operations.

[Means to solve the problem]

The magnetic disk device of the present invention uses one surface of the magnetic disk as a servo surface, writes position information on the servo surface in advance, and demodulates the position information read by a read-only servo head. The position signals are generated as a position signal, and the position signals are different in phase by 90 degrees from each other and change in a triangular wave shape with respect to the movement of the head. In a magnetic disk device using a two-phase sabot system that selects a slope, moving (seek) the head from its current track position to an adjacent track position 1
By switching the cylinder seek from the slope of the position signal of the current track position to the slope of the position signal corresponding to the adjacent track position to be moved (seek),
It is configured by performing one cylinder seek with only position control.

〔Example〕

Next, one embodiment of the present invention will be described in detail with reference to the drawings.

As shown in FIG. 3, this embodiment controls the positioning of the head with respect to the information recording concentric tracks of the magnetic disk 14 in the head disk assembly (HDA) 16, and the head 41 is usually a voice coil. - Moved by a motor-type drive device 40.

The positioning operation includes a speed control mode and a position control mode, which are switched by the mode switching circuit 35.

A servo head output signal 17 indicating position information read out by the servo head 39 is demodulated into a position signal 19 by a position signal demodulation circuit 18 . The position signal 19 is differentiated by an electronic tachometer 27 and output as a speed signal 24 indicating the actual speed of the head 41. Further, a predetermined target speed is written in the ROM 29 according to the number of tracks from the current track position of the head 41 to the target track position, and by inputting the remaining track number signal 28, the target speed can be digitally determined. It is output as a speed reference signal 30. The digital speed reference signal 30 is input to the DA converter 31 and output as the speed reference signal 32, and the speed signal 2
4 and the speed reference signal 32 are input to a speed error signal generation circuit 33, which takes the difference between the speed signal 24 and the speed reference signal 32, and
By amplifying it, the speed mode drive signal 34 is output. Thereafter, the speed mode drive signal 34 is input to the mode switching circuit 35. The mode switching circuit 35 passes only the speed mode drive signal 34, and the speed mode drive signal 34 is input to the power amplifier 37 as a drive signal 36, and after current amplification, is input to the drive device 40 as a drive current 38, and the By driving the device 40, the head 41 is moved to the target tracking position.

Next, the position control mode of the present invention will be explained.

The position control is performed by closed-loop control of the position signal by PID compensation, and the servo head output signal 17, which is the output of the servo head 39, is demodulated into the position signal 19 by the position signal demodulation circuit 18, and is input to the slope selection circuit 15. do. The slope select circuit 15 selects a position signal 19 of a track that is a positioning target using a slope select signal 20 and outputs it as a selected position signal 21. Thereafter, the selected position signal 21 is input to an integrator circuit 22, and the integrator circuit 22 performs integral element compensation and proportional element compensation of PID compensation, and the selected position signal 21
Outputs 3. The integrated position signal 23 is input to a position signal summing amplifier 25.

In the position signal summing amplifier 25, the integrated position signal 23 is added to the speed signal 24, performs differential element compensation of PID compensation, and outputs a position mode drive signal 26. The position mode drive signal 26 is input to the mode switching circuit 35. The mode switching circuit 35 passes only the position mode drive signal 26, the position mode drive signal 26 is inputted as a drive signal 36 to a power amplifier 37, and after current amplification is inputted as a drive current 38 to a drive device 40, and the drive device 41 By driving the head 41, the head 41 is held at the target track position.

There are two modes for positioning operation, and in this embodiment, these modes are switched as follows.

First, in a track following operation (following the current track as it is), the track that is the target of positioning in the position control mode is set as the current track and is followed.

Next, in a seek operation for a track that is two or more cylinders away, the seek is first performed in the speed control mode, and when the target track approaches a distance of 1/2 track, the mode is switched to the position control mode to perform accurate positioning.

A seek operation to an adjacent track (one cylinder seek) is performed by changing the slope from that of the current track to that of the adjacent target track using the slope select signal 20 in the position control mode.

Next, for the above-mentioned 1 cylinder seek, from 1 track to 2
This will be explained in detail using a seek to a track as an example.

First, at the 1 track position, in the slope select circuit 15 shown in FIG. position signal N
, Q, N, and Q, only the position signal 4 is inverted by the inverting circuit of the operational amplifier circuit 13 shown in FIG. 1 and outputted as the selected position signal 21. At this time, selected position signal 2
1 is at ground level.

Next, when one cylinder seeks from the 1st track position to the 2nd track position, the slope select signal switches the on state from the slope select signal 8 to the slope select signal 5, and the on state of the analog switch is changed to the on state of the analog switch 12.
to analog switch 9. At this time, the position signal changes from the position signal 4 in FIG. 2 to the position signal N1, which is inverted by the inverting circuit shown in FIG. 1 and output as the selected position signal 21.

Here, at the 1 track position, the position signal N1 is a position signal at a positive voltage level as shown in Fig. 2, so immediately after switching the analog switch, a positive voltage is input to the inverting circuit shown in Fig. 1, and it is inverted. The selected position signal 21 is then outputted as a selected position signal 21 at a negative voltage level. The selected position signal 21 at the negative voltage level is then input to the integrator circuit 22, and position control is activated so that the selected position signal 21 at the negative voltage level becomes the selected position signal 21 at the ground level. One cylinder seek can be performed.

In the above example, the 1-cylinder seek is from the 1-track position to the 2-track position, but 1-cylinder seek is possible by similarly switching the analog switch of the slope select circuit 15 for other 1-cylinder seeks, and the position One-cylinder seek can be performed at high speed and with small transient response using only control.

〔Effect of the invention〕

As explained above, the present invention performs one-cylinder seek from the current track position to the adjacent track position by switching the slope of the position signal using the slope select circuit 15, thereby performing high-speed one-cylinder seek with small transient response after the seek using only position control. This has the effect of performing a cylinder shift operation.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a slope select circuit which is the main part of an embodiment of the present invention, and FIG. 2 is a position signal N input to the slope select circuit shown in FIG. 1. FIG. 3 is a block diagram of a positioning device according to an embodiment of the present invention having the slope select circuit shown in FIG. 1. 9.10,11.12... Analog switch,
18...Position signal demodulation circuit, 15...
slope select circuit, 22...integrator circuit,
25...Position signal summing amplifier, 27...
...Electronic tachometer, 29...ROM, 31
...DA converter, 33 ... Speed error signal generation circuit, 35 ... Mode switching circuit, 37
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Claims (1)

[Claims] One surface of the magnetic disk is used as a servo surface, position information written in advance on the servo surface is read out by a read-only servo head, and the position information is demodulated and changes in a triangular wave shape as the head moves. A magnetic disk drive using a two-layer servo type positioning means that generates first and second position signals having a phase difference of 90 degrees from each other and uses the position signals as negative feedback to form a feedback loop for position control with the head. , one cylinder seek for moving (seek) the head from the current track position of the head to an adjacent track position corresponds to the adjacent track position to be moved (seek) from the first position signal corresponding to the current track position. 1. A magnetic disk drive comprising means for performing one cylinder seek by controlling the position by switching to the second position signal.