JPH04289566A - How to measure magnetic head offset amount - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a method for measuring the amount of offset between heads that is applied to a magnetic head control system that positions a magnetic head using servo information recorded on a magnetic recording medium. The present invention relates to a magnetic head offset amount measuring method for measuring the offset amount such as thermal off-track between the servo head and the data head in a magnetic recording apparatus using both the servo method and the data surface servo method.

0002

2. Description of the Related Art Conventionally, in a magnetic head positioning control device for a magnetic disk device, for example,
As described in Publication No. 4, in order to detect the steady state error in the position of each magnetic head of a plurality of data recording/reproducing magnetic heads, the servo control magnetic head is forcibly offset, and the data recording/reproducing magnetic head is A device that detects a steady error between the data recording/reproducing magnetic head and the servo control magnetic head by performing a read test of specific data such as addresses on the track and counting the number of errors that occur. It has been known.

0003

[Problem to be Solved by the Invention] In the above-mentioned conventional technology, based on the result of a read test of specific data such as an address,
Steady error (
The measurement accuracy is poor because the head is measured by the amount of offset (amount of offset), and the time required for measurement is also long for heads with a large amount of offset. There was a problem with the controller waiting time being long.

Therefore, an object of the present invention is to measure the offset amount between a servo head and a data head in a short time, at high speed, and with high precision, thereby minimizing the waiting time of the host controller. The purpose is to provide a method.

Another object of the present invention is to perform a subsequent seek operation based on the measured offset amount data to accurately and quickly settle the data head on a target track of a magnetic recording medium such as a magnetic disk. An object of the present invention is to provide a method for measuring a magnetic head offset amount for controlling the positioning of a magnetic head.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a data recording medium (data recording medium) in which each track is provided with a servo information area for head position control and a data area alternately at required intervals. a data magnetic head corresponding thereto, and one or more servo recording media in which each track is provided with servo information for controlling the head position at regular intervals narrower than the arrangement interval of the servo information on the data recording medium. (servo recording surface) and a corresponding servo magnetic head to acquire servo information on the data recording medium and perform servo control for the position of the data magnetic head based on this servo information. Acquire the servo information of the recording medium, and calculate the amount of offset between the servo magnetic head and the data magnetic head from the difference between the servo information of this servo recording medium and the servo information of the data recording medium acquired immediately before and/or after it. It is characterized by being configured to do so.

As a preferred example, the magnetic recording medium is a magnetic disk, and the interval of servo information recorded on the servo recording surface is half the interval (sector length) of the servo information recorded on the data surface. 1 or less.

[0008]

[Operation] The operation based on the above configuration will be explained.

According to the present invention, in a magnetic recording medium drive device, one of the plurality of magnetic recording media (recording surfaces) such as magnetic disks is used exclusively for servo (servo recording medium), and the rest are used for data and servo information. (data recording medium). On the data recording medium, servo information and data for head position control are arranged alternately (for each sector) on each track, and the data magnetic head corresponds to the recording surface of this data recording medium. The servo information of the servo method) is recorded. Servo information of a so-called servo surface servo system is recorded on the servo recording medium at narrower intervals (for example, 50 μsec) than the servo information of the data recording medium. When measuring the offset amount of the data magnetic head with respect to the servo magnetic head (in a system where the data surface servo method and the servo surface servo method are used together), the servo value obtained from the target data magnetic head is measured. Based on the information, the head positioning operation (track following operation) is performed, and during this time (using the idle time of the following control) the offset amount between the heads is calculated from the servo information obtained from the servo magnetic head in a time-sharing manner. Therefore, it is possible to measure and hold the offset amount with high accuracy in a short time.

[0010] Further, the subsequent seek operation is performed using both the servo surface servo method, which performs servo control using servo information on the servo recording surface, and the data surface servo method, which performs servo control using servo information on the data recording surface. be done. here,
During a seek, servo information is obtained from the servo head and the seek is performed to the vicinity of the target track. At this time, offset information of the target track is added to the servo information used to perform servo control. Even when switching from the data head to the data head, undesired overshoots and undershoots in control can be reduced, which is effective in shortening access time.

In addition, the amount of offset between the servo magnetic head and the data magnetic head is measured at regular intervals as described above, and the track following control of the target magnetic head is performed using servo information corrected for the measured offset amount. It is possible to perform positioning control including time division control (discrete control).

0012

[Embodiments] Hereinafter, embodiments of the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram of a servo control system to which this embodiment is applied. In FIG. 1, 1 is a data surface magnetic head, and 2 is a servo surface magnetic head. Also,
3a and 3b are magnetic disks, of which 3a is a data surface disk and 3b is a servo surface disk. 4
is the carriage that supports heads 1 and 2, and 5 is the head IC
, 6 is a read/write IC, and 7 is a servo signal detection circuit. Furthermore, 8 is an A/D converter, 9 is a microprocessor (MPU), 10 is a D/A converter, 11 is a power amplifier, and 12 is a voice coil motor (VCM).

FIG. 2 shows the structure of data on the disk surface according to this embodiment. FIG. 2(a) shows the structure of data on the servo surface, and in a portion shown at 30, an absolute track number and a burst signal for position deviation detection are recorded. When the disk rotates steadily, this signal is 50μ
It exists with a period of sec. FIG. 2(b) shows the structure of data on the data surface, where a burst signal for detecting positional deviation is recorded in a portion 31, and a portion 32 is a user data recording area. . The burst area 31 and the user data area 32 constitute one sector. Here, the length of one sector is 200 μsec, so when the disk is rotating steadily, the burst signal is 200 μsec long.
It exists with a period of μsec.

Information recorded on the magnetic disk 3a or 3b is read out by the head 1 or 2. At this time, the head IC 5 outputs the read signal of the head designated by the MPU 9 to the read/write IC 6. The read/write IC 6 amplifies this signal and outputs it to the servo signal detection circuit 7. When the servo signal detection circuit 7 detects a signal with a fixed pattern that is always present at the beginning of the servo signal from among the input read signals, it selects a servo head according to the selected head. When the absolute track number is input next to the detected signal, it demodulates the absolute track number that is input next to the detected signal, generates a position deviation signal from the subsequent burst signal for detecting the position deviation signal, and outputs it to the A/D converter 8. , starts the A/D converter 8. Also, when the data head is selected, since no absolute track number is recorded on the data surface, a position deviation signal is generated from the burst signal for position deviation signal detection and output to the A/D converter 8. Then, the A/D converter 8 is activated. At this time, regardless of the selected head,
The servo detection circuit 7 outputs an interrupt control signal to the MPU 9.

[0016] When the interrupt control signal is input, the MPU 9 stops executing the program up to that point and starts the interrupt control program. FIG. 3 shows the flowchart. M.P.
When the power is turned on, U7 performs an interrupt wait operation (processing 50). Next, in interrupt control, when an interrupt control signal is input from the servo signal detection circuit 7, M
Check whether the value of memory S inside PU9 is 0 or 1 (process 6
0), when S is 0, the position signal y(n) is taken in from the A/D converter 8 (processing 61), and the output value is output to the D/A converter based on the value of this y(n). (process 62),
Output u(n) to the D/A converter (process 63). After this, various variables for following control are calculated (
Process 64), the selected head is switched from data head 1 to servo head 2 (process 65), 1 is assigned to memory S (process 66), and the interrupt control is ended. When S=1, the position signal y(n+1) is taken in from the D/A converter 8 (processing 67), and the offset amount between the servo head 2 and the data head 1 is calculated x=y(n+1)-y
(n) is calculated (process 68). After this, the selected head is switched from servo head 2 to data head 1 (process 69), and 0 is assigned to memory S (process 70).
, terminate interrupt control.

Here, by processing 63, the D/A converter 1
u(n) outputted to 0 is converted to an analog voltage by a D/A converter 10, amplified by an amplifier 11, and then outputted to a VCM (Voice Coil Motor).
It is input to the driver 12 and drives the carriage 4.

According to this embodiment, it is possible to measure the amount of offset between heads without the host controller performing read/write operations, and furthermore, it is possible to measure the amount of offset between heads without having to perform read/write operations. Since one piece of data can be acquired, there is an effect that the waiting time of the upper controller can be minimized.

Furthermore, when the offset between the heads is measured using this method, the amount of offset can be accurately measured with an accuracy of 1 μm or less, so when seeking to the target track, the amount of offset between the servo head and the data head can be measured accurately. The corrected position signal makes it possible to perform high-precision head positioning control, and as a result, undesirable overshoots and undershoots are less likely to occur in control, and the head can quickly settle and follow the target track. There is also this effect.

Furthermore, according to this embodiment, the time required for the head to pass through one sector on the data disk (200 μs
ec), the amount of offset between the servo head and any one data head can be measured with an accuracy of 1 μm or less, making it possible to reduce the waiting time of the host controller during measurement.

[0021]

As explained in detail above, according to the present invention, the amount of offset between a servo magnetic head and any one data magnetic head can be reduced with a very short servo information arrangement interval on a data magnetic recording medium. can be measured with high accuracy in a very short time based on the servo information between both magnetic recording media, so that the waiting time for the higher-level controller during measurement can be reduced.

Furthermore, according to the present invention, when seeking to a target track, it is possible to correct and control the amount of offset between the servo magnetic head and the data magnetic head, so that undesired overshoot or undershoot occurs. This has the effect that the head can be quickly positioned and followed the target track.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a servo control system to which an embodiment of the present invention is applied.

FIG. 2 is a configuration diagram of data on a disk surface according to an embodiment of the present invention.

FIG. 3 is a flowchart of a servo control program according to an embodiment of the invention.

[Explanation of symbols]

1 Magnetic head for data recording surface (data magnetic head)
2 Magnetic head for servo recording surface (servo magnetic head)
3a Data surface disk (data recording medium) 3b
Servo disk (servo recording medium) 4 Carriage 5 Head IC 6 Read/write IC 7 Servo signal (servo information) detection circuit 8 A/
D converter 9 Microprocessor (MPU) 10 D/A converter 11 Amplifier 12 VCM driver 30 Servo information area 31 on servo surface (servo recording medium) Servo information area 32 on data surface (data recording medium) (recording medium) user data area

Claims (1)

[Claims] 1. A data recording medium in which each track is provided with a servo area for head position control and a data area alternately at predetermined intervals, and a data magnetic head corresponding thereto;
Using one or more servo recording media in which servo information for head position control is provided on each track at regular intervals narrower than the arrangement interval of the servo information on the data recording medium, and a corresponding servo magnetic head, While acquiring servo information on the data recording medium and performing servo control for the data magnetic head position based on this servo information,
During this time, the servo information of the servo recording medium is acquired, and the amount of offset between the servo magnetic head and the data magnetic head is calculated from the difference between the servo information of this servo recording medium and the servo information of the data recording medium acquired immediately before and after. A method for measuring an offset amount of a magnetic head, characterized in that it is configured as follows.