JPH05307843A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To lessen the delay at the time of the speed control of a magnetic head and to improve the follow-up performance of the magnetic head without using various computations for estimation of magnetic head speeds and various kinds of speed detectors. CONSTITUTION:The magnetic head 11 under movement reads the position information indicating its own position at suitable sampling intervals from a medium 14 and outputs the information via a servo processing circuit 12 to a CPU 1. The CPU 1 reads the target position information corresponding thereto from a target position table 21 and compares the information with the position information from the magnetic head 11 when the position signal fro the magnet head 11 is inputted to the CPU 1. The resulted position error data is applied as an analog position error signal 100 by a D/A converter 3 to a speed control system of the magnetic head 11 consisting of an amplifier 4, a differentiator 6, an amplifier 7, an adder 5, a filter 8, a current amplifier 9, a VCM 10, the magnetic head 11, a servo processing circuit 12 and the CPU 1 which controls the speed of the magnetic head 11 until the position error signal 100 attains 0.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk device, and more particularly to control of the moving speed of a magnetic head when moving the magnetic head to a target track.

[0002]

2. Description of the Related Art Conventionally, in a magnetic disk device, the position information of the magnetic head read by the magnetic head is used as a CP.
The magnetic head is converted into velocity information by U, the velocity information is compared with the target velocity information read from the target velocity table stored in advance in the ROM or the like, and the difference between the two velocities becomes zero. A configuration for controlling the speed of is adopted. In such a conventional configuration, the position information read by the magnetic head must be converted into speed information using a CPU or the like. However, when the sector servo method is used, the sampling time when the magnetic head reads position information is long. Therefore, when the differential speed detection method is used when converting the position information into speed information, the detected speed is There is a drawback in that an error occurs between the speed of the actual magnetic head and the delay due to this error becomes considerably large, which deteriorates the tracking performance of the magnetic head.

Therefore, in order to correct the above-mentioned delay, a velocity estimation observer is used to reduce the error when converting the position information obtained from the magnetic head into velocity information, or the velocity of the magnetic head. It has been practiced to reduce the error by using various speed detectors for detecting. However, the use of the speed estimation observer causes a drawback that the calculation in the CPU becomes complicated and the load on the CPU increases, and the speed detector for detecting the speed of the magnetic head makes the apparatus expensive. At the same time, there is a drawback that it hinders the miniaturization of the device. Moreover, the magnetic head speed control device using the target speed table has to convert the position information into the speed information by the CPU as described above, even though the magnetic head reads the position information. As a result, the structure of the apparatus becomes complicated and the delay becomes large when the above-mentioned sector servo system is used. Therefore, the structure itself using the target speed table has a problem.

[0004]

In the conventional magnetic head speed control device using the target speed table as described above, when the differential speed detection method is used when converting the position information read by the magnetic head into speed information, The sector servo system has a drawback that the delay in controlling the magnetic head becomes large. So, as a method to correct this delay,
A speed estimation observer or various speed detectors for detecting the speed of the magnetic head must be used, but this causes a load on the CPU when converting the position information into speed information, or There is a drawback that the device becomes expensive and the miniaturization of the device is hindered.

Therefore, the present invention eliminates the above-mentioned drawbacks and reduces the delay in controlling the speed of the magnetic head without using a complicated magnetic head speed estimation calculation and various speed detectors to follow the magnetic head. It is an object of the present invention to provide a magnetic head speed control device that can improve the cost at low cost.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a magnetic disk apparatus for controlling the moving speed of a magnetic head to move the magnetic head to a target position on a magnetic disk, the time elapsed after moving the magnetic head. Storage means for storing the data indicating the target position where the corresponding magnetic head should be positioned, input means for inputting position information of the current magnetic head read by the magnetic head, and input by this input means. Comparing means for comparing the position information with the target position information in the table data stored in the storing means to obtain difference data between the two, and the difference data obtained by this comparing means becomes zero. And a speed control means for controlling the moving speed of the magnetic head.

[0007]

The storing means stores the table data indicating the target position where the magnetic head should be positioned, which corresponds to the time elapsed after the magnetic head is moved. The input means inputs the position information of the current magnetic head read by the magnetic head. The comparison means compares the position information input by the input means with the target position information stored in the storage means to obtain difference data between the two. The speed control means controls the moving speed of the magnetic head so that the difference data obtained by the comparison means becomes zero.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a magnetic head speed control device of the present invention. 1 is a CPU that obtains position error data 100 by calculating the difference between the target position information read from the target position table 21 in the ROM 2 and the position information read by the magnetic head 11 that is input from the servo processing circuit 12; The ROM 3 which stores a target position table 21 in which the relationship between the elapsed moving time of the head 11 and the position to be taken by the magnetic head 11 is stored is a CPU 1
D / A converter for converting the position error data 100 output from the device into an analog position error signal 101, 4 an amplifier for amplifying the difference signal 101 and outputting it to the adder 5, 5 a position error signal and a velocity error signal Speed control signal 300
Is an adder, 6 is a differentiator that differentiates the difference signal 101 into a speed error signal 200, 7 is an amplifier that amplifies the speed error signal 200 and outputs the speed error signal 200 to the adder 5, and 8 is used when the magnetic head 11 is moved. Of the notch filter for suppressing the mechanical resonance point of the above, a lead filter for phase compensation of the speed control loop, etc., 9 is supplied to the voice coil motor (VCM) 10 based on the control signal output from the filter 8. A current amplifier that changes the current, 10 is a magnetic head 1
1 is a voice coil motor for driving 1, 11 is a medium 14
A magnetic head 12 reads and writes data from the upper track and reads position information from the track, and 12 extracts position information of the current position of the magnetic head 11 from various information read from the magnetic head 11 and outputs it to the CPU 1. A servo processing circuit 13 for processing the data read by the magnetic head 11 or outputting data to be written to the magnetic head 11 to the magnetic head 11.
The write circuit 14 is a medium for reading and writing data by the magnetic head 11, and has a plurality of tracks for reading and writing the data.

FIG. 2 is a diagram showing an example of data in the target position table 21 stored in the ROM 2 shown in FIG. In the figure, the horizontal axis represents the time elapsed when the magnetic head moves, and the vertical axis represents the target position where the magnetic head should be located corresponding to the time. These relationships are indicated by a in the figure. It is shown by the curved line. Therefore, the CPU 1 retrieves the target position data corresponding to the time elapsed when moving the magnetic head 11 from the target position table 21,
This will be compared with the position information where the magnetic head 11 is actually positioned. Here, in the drawing, C, D, E, and F are the magnetic heads 11 when the magnetic head 11 is moved from the remaining track 500 to the target position 0.
Each position of the movement locus of is shown. That is, C indicates the magnetic head movement start point, D indicates the position at the time when the movement of the magnetic head 11 reaches the maximum speed, and E indicates the magnetic head 11.
Indicates the position at the time when the movement of No. starts deceleration, and F indicates the time at which the final target track 0 is reached and the seek ends. Among these points, C, D, and E have a constant relationship for the reason described below. Therefore, in order to simplify the calculation of the CPU 1, the position information of these points on the target position table is set in advance. Is also stored in the ROM 2 for each remaining track amount. Here, the magnetic head 1
Assuming that the acceleration of the magnetic head 11 by the VCM 10 when moving 1 is constant, the position D point at which the magnetic head 11 reaches the maximum speed is determined when the position of C is determined. From the time point B in FIG. 2 when the magnetic head 11 reaches the point D, the speed control loop of the magnetic head speed control device shown in FIG. 1 starts to operate. From the point D to the point E, the magnetic head 11 moves at a constant speed and moves at the maximum speed. Point E is the deceleration start position of the magnetic head 11, and the distance between points E and F is always constant. Therefore, if the position of point C is determined, the position of point E is also determined. Therefore, C
The positional relationship among points D, E and E always has a fixed relationship.

Next, the operation of this embodiment will be described. C
The PU 1 calculates the remaining track amount existing between the track on which the magnetic head 11 is located immediately before the magnetic head 11 starts moving and the target track on which the magnetic head 11 is moved. When the CPU 1 knows the remaining track amount (here, for example, 500), the ROM 2
After confirming the position of the corresponding point C in FIG. 2, the current amplifier 9 is controlled to supply the maximum current to the VCM 10 to accelerate the magnetic head 11. Here, the moving distance of the magnetic head 11 is constant until the magnetic head 11 accelerates from the stationary state to reach the maximum speed. Therefore, the CPU 1 can know the position (corresponding to the number of remaining tracks existing between the final target track and the current position) when the magnetic head 11 reaches the point D in FIG. On the other hand, when the magnetic head 11 starts moving, it moves across the tracks on the medium 14 and moves toward the target track. At this time, the position information of the tracks that the magnetic head 11 crosses (this is the magnetic field). The same) is read at the position of the head 11 and is output to the CPU 1 via the servo processing circuit 12. As a result, the CPU 1 stops the maximum current supply operation from the current amplifier 9 to the VCM 10 at the time B when it is determined that the magnetic head 11 has reached the position of the point D based on the position information obtained from the magnetic head 11. Then, the speed control of the magnetic head 11 by the speed control loop is started.

That is, in the CPU 1, the magnetic head 11 is D
When the magnetic head position information is input from the magnetic head 11 via the servo processing circuit 12 from the time point b when the point is reached,
The target position information in the target position table 21 corresponding to that time point is read, the difference between the read target position information and the position information input from the magnetic head 11 is calculated, and this is calculated as the position difference data 100 and D / A converter 3
Output to. The D / A converter 3 converts the input digital position error data 100 into an analog position error signal 101 and outputs it to the amplifier 4 and the differentiator 6. The amplifier 4 amplifies the input position error signal 101 to adder 5
Output to. On the other hand, the differentiator 6 differentiates the input position error signal 101 into a velocity error signal 200, which is output to the adder 5 via the amplifier 7. The adder 5 is the amplifier 4
The position error signal input from the amplifier and the speed error signal input from the amplifier 7 are added, and the result is used as the speed control signal 300 of the VCM 10 via the filter 8 and the current amplifier 9.
Output to. The current amplifier 9 receives the input speed control signal 3
The current supplied to the VCM 10 is changed in the direction in which 00 becomes 0.

By such an operation, the moving speed of the magnetic head 11 driven by the VCM 10 is changed so that the control signal becomes zero. The fact that the speed control signal becomes 0 corresponds to that the position error data 100 calculated by the CPU 1 becomes 0. After all,
CPU 1, D / A converter 3, amplifier 4, differentiator 6, amplifier 7, adder 5, filter 8, current amplifier 9, VCM1
0, the magnetic head 11, the servo processing circuit 12, and the CPU 1 have a speed control loop from the point D in FIG.
The position of the magnetic head 11 (which is the same as the position information read from the magnetic head 11 and input via the servo processing circuit 12) that changes with the passage of the moving time of 1 becomes the corresponding target position in the target position table 21. The moving speed of the magnetic head 11 is controlled so that they coincide with each other. Also, CPU1
When the magnetic head 11 reaches the vicinity of the final target track F shown in FIG. 2, the position control of the magnetic head 11 is switched to a transient position control system (not shown) to move the magnetic head 11 to the final target position F. Make it reach.

In the speed control loop shown in FIG. 1, the speed control loop only via the differentiator 6 and the amplifier 7
When the moving speed of the magnetic head 11 is controlled, since this loop is a primary system, a steady speed deviation is inevitably generated, and it becomes difficult for the magnetic head 11 to reach the target track. Therefore, a path for adding the position error signal 101 obtained via the amplifier 4 to the speed error signal 200 output from the differentiator 6 by the adder 5 is provided side by side to make the speed control loop a secondary system. Therefore, the steady speed deviation is set to zero.

According to this embodiment, the target position table is stored in the ROM 2 instead of the target speed table, and the target position to be located by the magnetic head 11 read from this target position table and the target position table are obtained from the magnetic head 11. The difference between the current position information of the magnetic head 11 and the current position information is CP.
U1 is calculated as position error data, and the moving speed of the magnetic head 11 is controlled to move the magnetic head 11 to the target track so that the position error data becomes 0. It is not necessary to differentiate the obtained position information to convert it into speed information, and the structure of the device can be simplified and the device can be made inexpensive. In addition, since the position information obtained from the magnetic head 11 is not converted into speed information as described above, the CPU 1 does not need to perform differential speed detection, and therefore the delay due to the speed detection error does not occur even if the sector servo method is used. The tracking performance of the magnetic head 11 can be improved without using a special calculation method or parts.

[0015]

As described above, according to the present invention, the delay in controlling the speed of the magnetic head can be reduced and the follow-up of the magnetic head can be achieved without using a complicated magnetic head speed estimation calculation and various speed detectors. Performance can be improved at low cost.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a magnetic head speed control device of the present invention.

FIG. 2 is a diagram showing an example of data in a target position table shown in FIG.

[Explanation of symbols]

1 ... CPU 2 ... ROM 3 ... D / A converter 4, 7 ... Amplifier 5 ... Adder 6 ... Differentiator 8 ... Filter 9 ... Current amplifier 10 ... Voice coil motor 11 ... Magnetic head 12 ... Servo processing circuit 13 ... Read / Light circuit

Claims (1)

[Claims] 1. A magnetic disk device for controlling a moving speed of a magnetic head to move the magnetic head to a target position on a magnetic disk, wherein the magnetic head corresponds to a lapse of time after moving the magnetic head. Storage means for storing data indicating a target position to be stored, input means for inputting position information of the current magnetic head read by the magnetic head, position information input by this input means and the storage means Comparing means for obtaining the difference data between the two by comparing the corresponding target position information in the data stored in, and the moving speed of the magnetic head so that the difference data obtained by this comparing means becomes zero. And a speed control means for controlling the magnetic disk drive.