JPH0581802A - Device that performs position correction with the micropositioning function - Google Patents

Abstract

(57) [Abstract] [Purpose] An object of the present invention is to provide a device for position correction by micro-calibration, which is capable of correcting misalignment between the head and the track in the on-track state and realizing highly accurate data reading. To do. [Structure] By providing a position information analysis circuit 20 for analyzing a change in position information output due to a minute vibration given to the head by the micropositioning mechanism 18 in the on-track state, the micropositioning mechanism 18 performs It is configured such that a minute vibration is applied to the head, a change in position information output due to the minute vibration is processed to generate position correction information, and the position correction is performed by the position correction information.

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 or the like, and a device for performing position correction by a micropositioning function.

[0002]

2. Description of the Related Art A magnetic disk device moves an arm having a plurality of heads in order to simultaneously read and write a plurality of magnetic disk media.

It is often practiced to provide a plurality of tracks for writing data in the circumferential direction of a magnetic disk medium and further use one surface of the plurality of magnetic disk media as such servo tracks for alignment.

Although a plurality of magnetic disk media rotate about the same rotation axis, the cylinders on all the disks are not always exactly at the same cylinder position because of the eccentricity of the disks and the rotation axis and the inclination of the shaft. I can't say that

Therefore, it is necessary to minutely correct the position of the head for each surface of each disk. In order to perform such a correction, a micro-positioning mechanism is provided for each head on the arm that moves the head to perform a minute correction.

FIG. 4 is a block diagram of such a conventional magnetic disk device. In the figure, 11 is a control unit that controls the magnetic disk device, 12 is a microprocessor that performs control according to a program in a read-only memory (ROM) 13 in the control unit 11, 13 is a ROM that stores the control program,
Reference numeral 15 is a voice coil motor (VC
M), 14 are voice coil motor drive circuits (abbreviated as VCM drive circuits) for driving the voice coil motor (VCM) 15, 16 is an arm on which a plurality of heads 17 are mounted, 17
Is a head for reading and writing recorded data on the disk medium, 1
Reference numeral 8 is a micropositioning mechanism for individually correcting the position of the head 17, and 19 is a random access memory (RAM) for storing position correction information. A piezo element is often used in the micro-positioning mechanism in order to make the head compact and lightweight and move the head at high speed.

The magnetic disk device drives the VCM drive circuit 14 to start the VCM 15 when the device is powered on and started up.
Therefore, the arm 16 is moved from end to end of the track, and the head 17 reads the servo track data to perform the calibration seek operation for confirming the position information.
At this time, VCM at on-track of each position of the medium
The drive voltage is monitored and recorded to obtain the correction information for the external force of the VCM, and the position information obtained by reading the servo pattern of the servo surface is recorded to obtain the correction information of the tilt of the medium and the rotation axis and the eccentricity. Also, the servo system open loop information is acquired and stored in the RAM 19.
The correction amount of the head has a servo track on a part of each data surface. By accessing this part, the position deviation of each data head from the servo head is detected, and the micropositioning mechanism is used for minute position correction of the head with this information. Controlled by 18.

By thus aligning the head with the tracks on each surface of the disk medium, accurate data reading and servo stability can be achieved. Furthermore, when time elapses after the power of the device is turned on, the temperature inside the device rises, the difference in the coefficient of thermal expansion of the materials such as the disk medium and the arm, and the fluctuation of the driving current due to the temperature characteristics of the VCM driving circuit 14 cause the track Therefore, there is a problem in that the misalignment of the head position occurs. Therefore, the calibration seek operation is performed every preset time, and the misalignment due to the temperature change is corrected. However, a phenomenon occurs in which there is a sudden displacement due to a shock or the like that occurs during the calibration seek interval, and further correction is necessary.

[0009]

However, there is a problem in that there is a sudden displacement of the position due to an impact or the like generated during the calibration seek interval, and further correction is required.
In view of such a point, it is an object of the present invention to provide means for generating position correction information and performing position correction in an on-track state.

[0010]

The above-mentioned problems can be solved by an apparatus for correcting the position by the micro-positioning function configured as follows. FIG. 1 is a principle diagram of the present invention.

In an apparatus for correcting track positioning by providing a micro-positioning mechanism 18 that moves an arm 16 having a plurality of heads 17 to position it on a cylinder, and minutely moves the heads 17, in a track-on state, By providing a position information analysis circuit 20 for analyzing a change in position information output due to a minute vibration given to the head by the micropositioning mechanism 18, a minute vibration is given to the head by the micropositioning mechanism 18 in an on-track state. It is configured to process the fluctuation of the position information output due to the minute vibration, generate the position correction information, and perform the position correction by the position correction information.

[0012]

In the on-track state, the micro-positioning mechanism 18 gives a slight vibration to the head.

The position information analysis circuit 20 processes the fluctuation of the position information output due to the minute vibration to generate the position correction information, and performs the position correction based on the position correction information.

[0014]

FIG. 2 is a block diagram of a magnetic disk device according to an embodiment of the present invention. In the figure, reference numeral 20 is a position information analysis circuit for performing an analysis process of an output fluctuation due to a minute vibration given to the head by the micropositioning mechanism 18 in an on-track state. In addition, the same reference numerals as those in FIG. 4 are the same.

The operation of FIG. 2 will be described with reference to the explanatory view of the embodiment of the present invention of FIG. The control until the shift to the steady use state is the same as the conventional one, and therefore will not be described. In a steady use condition, when micro-vibration is applied to the head in the diameter direction by the micro-positioning mechanism 18 in the on-track condition after positioning on the target cylinder in the servo track, the head output deviates from the track due to the micro-vibration, and thus the position information is obtained. A slight change occurs in the output. The head output is shown in FIG. The head output enters the control unit 11 by the position information analysis circuit 20 and digital position information is generated by the A / D converter. The position correction information is generated as follows.

The position information output based on the servo data obtained from the servo head is sampled at regular time intervals, and the value is At-1, where the time from the reference time is t,
At, At + 1, ... The vibration is inside when t-1 and outside when t + 1.

(At + 1-At-1) / 2-At is calculated to determine whether it is positive or negative, and this is used as position correction information. If the position correction information is positive, the micropositioning mechanism 18 moves the head outward. , If negative, move one unit inward. The size of one unit to move is set sufficiently smaller than the track interval.

By performing this operation at any time, it is possible to obtain and correct the positional deviation information between the head and the track in a steady use state, and it is possible to realize highly accurate data reading.

[0019]

As is apparent from the above description, according to the present invention, it is possible to correct the positional deviation between the head and the track in the on-track state, and it is possible to obtain highly accurate data reading and a stable servo system. It has a remarkable industrial effect.

[Brief description of drawings]

FIG. 1 is a principle diagram of the present invention.

FIG. 2 is a configuration diagram of a magnetic disk device according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram of an embodiment of the present invention.

FIG. 4 is a configuration diagram of a conventional magnetic disk device.

[Explanation of symbols]

11 Control Unit 12 MPU 13 ROM 14 VCM Drive Circuit 15 VCM 16 Arm 17 Head 18 Micro Positioning Mechanism 19 RAM 20 Position Information Analysis Circuit

Claims (1)

[Claims] 1. A micropositioning mechanism (18) for moving an arm (16) having a plurality of heads (17) to position it on a cylinder, and finely moving the head (17) to correct track positioning. In the device to perform, the micro-positioning mechanism (1
By providing a position information analysis circuit (20) that analyzes and processes changes in position information output due to minute vibrations given to the head by (8), the minute vibration is applied to the head by the micropositioning mechanism in the on-track state. An apparatus for performing position correction by a micropositioning function, which is characterized by processing a change in position information output due to vibration to generate position correction information and performing the position correction based on the position correction information.