JPH04263174A - Magnetic disk apparatus - Google Patents

Abstract

PURPOSE:To control a driving motor by means of the difference between the movement speed of a head detected from the inclination of a position error signal and the reference speed corresponding to the content of a difference counter at the positioning movement operation of a magnetic head and to increase the movement speed of the head. CONSTITUTION:A cylinder detection circuit 17 detects, from a servo signal 11, a cylinder address which has been written in the cylinder address area of a servo area, and outputs the number of cylinders 18 through which a magnetic head has been passed until a next servo area is read out from one servo area. A speed detection circuit B 19 detects the movement speed of the magnetic head from the number of cylinders 18. When the speed is within a prescribed speed, a low-speed movement signal 20 is output. When, during the positioning movement of the head, a difference cylinder 22 on which a high-speed movement speed is to be set is designated from a host apparatus, a driving current 30 is supplied to a driving motor while information on a cylinder address is being read out. A driving motor is controlled according to the difference between the movement speed of the head 5 and the reference speed according to the content of a counter 21.

Description

[Detailed description of the invention]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk drive, and more particularly to a magnetic disk drive using a data surface servo method for positioning a magnetic head using servo signals.

[Prior Art] In a magnetic disk drive, a large number of data tracks are formed on an information recording surface.
In writing and reading operations, it is necessary to position the magnetic head on the target data track (cylinder). As a method for positioning a magnetic head, there is a data surface servo method in which a part of each data track corresponding to a magnetic head of a magnetic disk device is used as an information area (servo area) for positioning. FIG. 3 is a circuit block diagram of a conventional data surface servo type magnetic disk device. In FIG. 3, a magnetic disk plate 31 is a recording medium that actually stores data, and is fixed to a spindle 33 and driven to rotate at high speed. FIG. 4 is a plan view showing how the recording surface of the magnetic disk plate in FIG. 3 is divided. In FIG. 4, a recordable area on the recording surface of the magnetic disk plate 31 is called a recording area 39. The storage area 39 is divided into a servo area 40, which is a servo signal storage area for head positioning, and a data area 41, which stores actual data. Although eight servo areas 40 are shown in this figure, the present invention is not limited to this. Further, a servo track is provided in the servo area 40, and a servo track is provided in the data area 41.
A plurality of data tracks are arranged concentrically in each. In FIG. 3, the number of magnetic heads 32 corresponding to the recording surfaces on which data is stored is mounted on a head positioning mechanism 34, and the head positioning mechanism 34 is driven for positioning by a drive motor 35. Head selection circuit 36
is the magnetic head 3 specified by the host device of the magnetic disk device.
Select only one 2. Of the information recorded on the magnetic disk plate 31 read from the magnetic head 32 selected by the head selection circuit 36, only servo information (servo signal) is separated and input to the position error signal generation circuit 37. The position error signal generation circuit 37 demodulates the position error signal from the input servo signal. The positioning control circuit 38 controls the current flowing through the drive motor 35 based on the position error signal and the feedback signal of the drive current flowing through the drive motor 35. Here, the position error signal will be explained using FIG. 5. FIG. 5 is a configuration diagram of the servo area of the magnetic disk plate in FIG. 3. Data track 42 is servo area 40
The servo signal is written in the portion divided into 1/2 tracks. The first servo track 43a and the second servo track 43b in the servo area 40 are divided along the center line of the data track 42, and are magnetized so as to obtain signals of opposite polarity. magnetic head 3
2 is correctly located on the data track 42, the magnetic head 32 will be located on the boundary between the first servo track 43a and the second servo track 43b in the servo area 40, and the position error will be demodulated from the read servo signal. Signal 44 becomes zero. The position error signal 44 extracts a negative signal from the first servo track 43a and a positive signal from the second servo track 43b, and is demodulated as a signal proportional to the difference between the two signals. As a result, the position error signal 44 becomes a signal proportional to the displacement of the magnetic head 32, as shown in FIG. Since the position error signal 44 can only be obtained from the servo area 40, while the magnetic head 32 is in the data area 41, it holds the position error signal 44 demodulated in the previous servo area 40, and then The position error signal 44 is read out and newly demodulated. FIG. 6 is a diagram showing a position error signal when the magnetic head moves. The position error signal 44 obtained in this manner becomes a signal as shown in FIG. 6(a) while the magnetic head 32 is moving for positioning. Further, since the slope of the position error signal 44 is proportional to the moving speed of the magnetic head 32, it is used to detect the moving speed. FIG. 7 is a detailed block diagram of the positioning control circuit in FIG. 3. In FIG. 7, the speed detection circuit 45 outputs a speed signal 46 proportional to the slope of the position error signal 44.
Output. The level detection circuit 47 is a circuit that detects the zero level of the position error signal 44, and outputs one cylinder pulse 48 each time the position error signal 44 reaches the zero level. During the positioning movement of the magnetic head 32, the cylinder pulse 4
By counting the number 8, it is possible to know the number of cylinders to which the magnetic head 32 has moved. Before a head positioning operation is performed, the difference counter 49 is set with the number of cylinders (difference cylinder) that is the difference between the cylinder where the magnetic head 32 is currently located and the target cylinder specified by the host device. During head positioning movement, the difference counter 49 receives the cylinder pulse 48.
1 count is subtracted each time. Difference counter 4
When the content of 9 becomes zero, it is assumed that the magnetic head 32 has reached the target cylinder, and the head positioning movement operation ends. On the other hand, the contents of the difference counter 49 are input to a speed conversion circuit 50 and converted into a reference speed signal 51 during head positioning movement. Furthermore, the output of the difference counter 49 is the specified value when the content of the difference counter 49 is greater than or equal to the specified value, and the value of the content of the difference counter 49 is output when it is below the specified value. The amplifier circuit 52 compares the speed signal 46 and the reference speed signal 51 and supplies a drive current 53 to the drive motor 35 (shown in FIG. 3) according to the difference between them. FIG. 8 is a diagram showing signal waveforms of each circuit in FIG. 7. In FIG. 8, (a) shows the reference speed signal 51, (b) shows the speed signal 46, and (c) shows the waveform of the drive current 53 which is the output of the amplifier circuit 52. The figure shows cases where the target is large (left half of the figure) and small (right half of the figure).

[Problems to be Solved by the Invention] In the head positioning movement operation in the conventional magnetic disk drive described above, the speed at which the magnetic head is actually moving is detected from a position error signal, and the speed is set based on this movement speed and a difference cylinder. The speed of the head positioning operation is controlled by controlling the drive motor of the head positioning mechanism according to the difference between the head positioning speed and the reference speed. Therefore, the position error signal becomes a very important signal for speed control. However, as shown in FIG. 6(b), the position error signal of the data plane servo method cannot obtain an accurate position error signal during high-speed movement. For this reason, conventional magnetic disk drives using the data surface servo system have the disadvantage that the moving speed of the magnetic head is limited and cannot sufficiently respond to high-speed movement.

[Means for Solving the Problems] A magnetic disk device of the present invention provides a servo area in which a servo signal is written in advance in a part or plural parts of a data track, and uses the servo signal of this servo area to drive a magnetic head. In a data surface servo type magnetic disk device for positioning, cylinder address information is written in the servo area, and the speed of head positioning operation is controlled by the supply time of a motor drive current supplied to a drive motor of a head positioning mechanism,
a speed control means for setting the supply time according to the number of cylinders to be moved; a speed adjustment means for adjusting the supply time controlled by the speed control means by reading the cylinder address information; and a target cylinder. drive current control means for controlling a drive current supplied to the drive motor according to an actual movement speed obtained from a position error signal generated from the servo signal and a set speed while the drive motor is moving at a low speed approaching the servo signal. There is. The speed adjusting means includes a cylinder detection circuit that detects a cylinder address from the servo signal, a speed detection circuit that detects the moving speed of the magnetic head from the output of the cylinder detection circuit, and a host device during the movement of the magnetic head. A difference counter that sets the difference cylinder specified by the difference counter, and the acceleration time of the set signal depending on the contents of this difference counter.
It may also include a set speed generation circuit that adjusts and outputs the deceleration time.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be explained with reference to the drawings. The magnetic disk device according to the present invention is basically the same as the conventional magnetic disk device shown in FIGS. 3 and 4. However, the information on the servo area of the magnetic disk plate of the magnetic disk device embodying the present invention is different from the conventional example as shown in FIG. 1, and the positioning control means is also different from the conventional example as shown in FIG. First, information on the servo area will be explained. FIG. 1 is a configuration diagram of a servo area of a magnetic disk plate of a magnetic disk device showing an embodiment of the present invention. Servo area 1 is cylinder address area 2
and a servo signal area 3. Like the conventional servo area 40 shown in FIG. 5, the servo signal area 3 is composed of a first servo track 4a and a second servo track 4b, each of which has a servo signal written therein. A position error signal 6 is generated from the servo signal read by the magnetic head 5. Cylinder address information is written in the cylinder address area 2, and the data track 7 is placed in the data area 8 by the magnetic head 5.
It is read in the same way as the data in . This makes it possible to know the number of cylinders that have passed from the reader of one servo area to the time of reading the next servo area during the positioning and movement operation of the magnetic head. Next, FIG. 2 is a configuration diagram of a positioning control means of an embodiment of the magnetic disk device of the present invention. The position error signal generation circuit 10 generates a servo signal 11
This circuit generates the position error signal 12 from the position error signal 12, and there is no difference from the position error signal generation circuit 37 of the conventional example. Speed detection circuit A13 is a circuit that detects the actual moving speed of the magnetic head from the slope of the end position error signal 12, and outputs a speed signal 14. Level detection circuit 15 detects cylinder pulse 16 from position error signal 12. The speed detection circuit A13 and the level detection circuit 15 are the same as the speed detection circuit 45 and level detection circuit 47 of the conventional example. Cylinder detection circuit 1
7 is a circuit that detects the cylinder address written in the cylinder address area 2 of servo area 1 from the servo signal 11, and detects the number of cylinders that the magnetic head passed between 18 and reading from one servo area to the next servo area. Output. Number of cylinders passed through speed detection circuit B19F: 1
The moving speed of the magnetic head is detected from 8, and a low speed moving signal 20 is output based on whether the detected speed is within a specified speed. During the positioning movement of the magnetic head, if the host device specifies a difference cylinder 22 whose movement speed does not exceed the specified speed, the low speed movement signal 20 remains "1" from beginning to end.
”.On the other hand, during the positioning movement of the magnetic head, the movement speed of the difference cylinder 2 exceeds the specified speed.
When 2 is specified, the low speed movement signal 20 is "0" at the beginning of the positioning operation, and becomes "1" when the movement speed once exceeds the specified speed and then falls below the specified speed again. The difference cylinder 22 designated by the host device is set in the difference counter 21. The contents of the difference counter 21 are subtracted by the number of cylinder pulses (16) or the number of cylinders (18) passed during the head positioning movement. At this time, if the low speed movement signal 20 is "1", the cylinder pulse 16 is subtracted, and the low speed movement signal 20 becomes "0".
If so, the number of cylinders passed through, 18, is subtracted. The set speed generating circuit 23 outputs a setting signal 30 such that the drive current 29 has a waveform shown in FIG. 8(c) in accordance with the difference cylinder 22. Generally, when the difference cylinder 22 is provided, the time during which the drive current 29 is in acceleration drive and the time in which it is in deceleration drive are uniquely determined. Therefore, the acceleration time and deceleration time are set in the setting signal 30 according to the difference cylinder 22. Furthermore, during the positioning movement of the magnetic head, the difference counter 21
The acceleration time and deceleration time of the setting signal 30 are adjusted according to the contents of the setting signal 30. The output of the difference counter 21 is converted into a reference speed signal 25 by a speed conversion circuit 24. This speed conversion circuit 24 is the same as the speed conversion circuit 50 of the conventional example. The differential amplifier circuit 27 outputs a signal according to the difference between the speed signal 14 and the reference speed signal 25. The switching circuit 26 is a circuit that switches and outputs the output of the differential amplifier circuit 27 and the setting signal 30, and when the low speed movement signal 20 is "1"
If so, the output of the differential amplifier circuit 27 is selected and output, and if the low speed movement signal 20 is "0", the setting signal 30 is selected and output. The amplifier circuit 28 amplifies the output of the switching circuit 26, converts it into a current, and outputs it as a drive current 29. Drive current 29 is supplied to drive motor 35 shown in FIG.

As explained above, the magnetic disk device of the present invention writes cylinder address information in the servo area of the magnetic disk plate, and when positioning and moving the magnetic head, it is possible to use the magnetic disk drive for disks that are scheduled to move at a high speed. When a reference cylinder is specified by the host device, the drive current is supplied to the drive motor according to the time while reading this cylinder address information, and when the drive motor decelerates to the specified speed, it is detected from the slope of the position error signal. By controlling the drive motor according to the difference between the moving speed of the magnetic head and the reference speed according to the contents of the difference counter, the moving speed of the magnetic head can be increased.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a servo area of a magnetic disk plate of a magnetic disk device showing an embodiment of the present invention.

FIG. 2 is a configuration diagram of head positioning control means of the magnetic disk device of the present invention.

FIG. 3 is a circuit block diagram of a conventional data surface servo type magnetic disk device.

FIG. 4 is a plan view showing how the recording surface of the magnetic disk plate in FIG. 3 is divided.

FIG. 5 is a configuration diagram of a servo area of the magnetic disk plate in FIG. 3;

FIG. 6 is a diagram showing a position error signal during movement of the magnetic head.

FIG. 7 is a detailed block diagram of the positioning control circuit in FIG. 3;

8 is a diagram showing signal waveforms of each circuit in FIG. 7. FIG.

[Explanation of symbols]

1, 40 Servo area 2 Cylinder address area 3 Servo signal area 4a, 4b, 43 Servo track 5, 32
Magnetic head 6 Position error signal 7, 42 Data track 8, 41 Data area 10, 37 Position error signal generation circuit 11
Servo signal 12, 44 Position error signal 13 Speed detection circuit A 14 Speed signal 15, 47 Level detection circuit 16, 48 Cylinder pulse 17 Cylinder detection circuit 18 Number of cylinders passed 19 Speed detection circuit B 20 Low speed signal 21, 49 Difference counter 22
Difference cylinder 23 Set speed generation circuit 24, 50 Speed conversion circuit 25, 51 Reference speed signal 26 Switching circuit 27 Differential amplifier circuit 28, 52 Amplifier circuit 29, 53 Drive current 30 Setting signal 31 Magnetic disk plate 33 Spindle 34 Head positioning Mechanism 35 Drive motor 36 Head selection circuit 38 Positioning control circuit 39 Recording area 45 Speed detection circuit 46 Speed signal

Claims (2)

[Claims] 1. A data surface servo type magnetic disk device in which a servo area in which a servo signal is written in advance is provided in one or more parts of a data track, and a magnetic head is positioned using the servo signal of this servo area. , write cylinder address information in the servo area, control the speed of the head positioning operation according to the supply time of motor drive current supplied to the drive motor of the head positioning mechanism, and set the supply time according to the number of cylinders to be moved. a speed control means; a speed adjustment means for adjusting the supply time controlled by the speed control means by reading the cylinder address information; and a speed adjustment means for adjusting the supply time controlled by the speed control means by reading the cylinder address information; A magnetic disk drive comprising drive current control means for controlling a drive current supplied to the drive motor according to an actual moving speed obtained from a generated position error signal and a set speed. 2. The speed adjusting means includes a cylinder detection circuit that detects a cylinder address from the servo signal, a speed detection circuit that detects the moving speed of the magnetic head from the output of the cylinder detection circuit, and It is characterized by consisting of a difference counter that sets the difference cylinder specified by the middle-level device, and a set speed generation circuit that adjusts and outputs the acceleration time and deceleration time of the set signal according to the contents of the difference counter. The magnetic disk device according to claim 1.