JPS61233477A - Head position deviation correcting system - Google Patents

Abstract

PURPOSE:To prevent off track caused by ambient temperature or heat generation by providing a servo track in at least one of outside or inside of the data track area of a magnetic disk and watching the lapse of time from seeking action and making correction. CONSTITUTION:When a new address is inputted to an address circuit before lapse of specified time from starting of the device, a timer sequence circuit 38 is informed that seek instruction is inputted. If specified time is lapsed since previous seek instruction, the timer sequence circuit 38 and a timer circuit 17 drive a positional deviation detecting operation circuit, and positions a magnetic head on the servo track and inputs a new positional deviation correction signal to a memory circuit 2 through a positional deviation correction signal circuit. Then, regular seek operation is executed and the position of the magnetic head is corrected obtaining a correction signal from the memory circuit 2.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to positioning correction of a magnetic head with respect to a data track on a magnetic disk surface in a magnetic disk storage device.

<Prior Art> There are mainly the following methods for detecting the position of a magnetic head in a magnetic disk storage device.

(1) Open loop method using a position detection mechanism that works with a magnetic head.

(2) A servo track system that uses a metal body on one side of the magnetic disk exclusively for the servo track.

(3) A sector servo method in which servo information is recorded in sector areas of data tracks on each disk surface and read by a magnetic head.

Of the above three methods, method (1) is currently widely used in small magnetic disk storage devices, but the position detected is the position of the position detection mechanism itself, and the data on the magnetic head and magnetic disk surface is detected. Place with the truck! ! Because there is no relationship, there are errors due to rotational eccentricity of the spindle, errors due to eccentricity etc. that occur when mounting on the spindle, errors due to differences in thermal expansion of each component, and the position of the magnetic head is in the correct positional relationship with respect to the position detection mechanism. Due to factors such as errors that occur during head alignment adjustment, in the case of a magnetic disk device that uses a magnetic disk with a diameter of 130 mm, the track density is 4007/1 nch.
(tracks/inch).

Method (2) detects the positional relationship between the servo track and the servo head, so the track density can be reduced to 90Q T/1n.
However, since one magnetic disk surface is used for the servo track, it is disadvantageous for small devices with a small number of disk surfaces.

Since method (3) uses a part of the disk surface for servo, information about the position of each magnetic disk surface and the magnetic head can be obtained, reducing error factors in head alignment, but servo information is Since it is recorded discretely on the data track, in order to obtain continuous position information,
It requires a position detection mechanism similar to the oven loop type, and the writing of servo data on the disk surface is complicated, making it difficult to erase servo information that is discretely placed on the data track. Alternatively, a wAl intrusion prevention device is required.

As a conventional technique that solves the drawbacks of the above methods (1), (2), and (3) and mainly aims to improve the recording track density in small magnetic disk storage devices, the features shown in FIGS. 3 and 4 are as follows. There is a publication No. 119907/1983. In FIG. 3, servo tracks 18 and 20 are provided on at least one of the outside and inside of a data track area 19 consisting of a large number of tracks arranged concentrically on a magnetic disk 17. These servo tracks 18, 20 are separately written before the magnetic disk 17 is attached to the magnetic disk device. Note that 21 is a sector slot and 22 is an index slot.

FIG. 4 is a block diagram of the above-mentioned conventional technology, in which 1 is an address circuit, 2 is a storage circuit, 3 is a positional deviation correction signal circuit, 4 is a read/write circuit, 5 is a drive signal circuit, 6 is an amplifier, 7 is an actuator, 8 is a position and speed signal circuit, 9 is a position detection mechanism, 1o is a position control circuit, 11 is a magnetic head,
12 is a magnetic disk, 13 is a spindle, 14 is a spindle drive mechanism, 15 is a sector detection mechanism, and 16 is a positional deviation detection operation circuit. The magnetic disk device shown in FIGS. 3 and 4 operates as shown below. Note that a description of the general operation of the device will be omitted.

When the device is started or when the error rate of read data exceeds a predetermined level, a positional deviation detection operation signal is input to the positional deviation detection operation circuit 16 according to a predetermined logical sequence, and the device enters the positional deviation detection mode. Become.

As a result, the positional deviation detection operation circuit 16 outputs a signal to the drive signal circuit 5 of the position control circuit 10 for positioning the magnetic head 11 on the servo track 18 or 20. A servo read signal from the magnetic head 11 is inputted into a positional deviation correcting circuit 3 via a reading/writing circuit 4 in order to determine the amount of positional deviation. This amount of positional deviation is the magnetic disk 1
Each sector detected by the sector detection mechanism 15 as the sensor 2 rotates is stored in the storage circuit 2 as a positional deviation correction signal. At this time, the memory circuit 2 receives an address signal corresponding to the sector signal from the address circuit 1, and the memory circuit 2 stores a positional deviation correction signal for each sector slot 21frJ. When the storage of the misregistration correction signal is completed, the device returns from the misregistration detection mode to the normal operating mode.

In the magnetic head position tracking operation in the normal operation mode, the data track designation signal in the data position designation signal is input to the drive signal circuit 5, the sector designation signal to the address circuit 1, and the head selection signal to the read/write circuit 4. ing. The tracking operation of the magnetic head 11 is performed while correcting the position by adding a positional deviation correction signal from the storage circuit 2 according to the rotational position of the magnetic disk to the data track designation signal in the data position designation signal. It will be done.

According to the above-mentioned prior art, the eccentricity error is corrected by the positional deviation of each sector on the data track, and the thermal expansion error is corrected by the servo track 18.20.
Errors in head alignment can be corrected by performing calculations based on the positional deviation of the designated data track according to the position of the designated data track.Errors in head alignment can be corrected by positional deviation of the outer or inner servo tracks.

By the way, the positional deviation detection operation signal in the above conventional technology is based on 5T506, which is currently the mainstream of small magnetic disks.
This type (Seagate technology type) does not exist and cannot be realized in practice.

<Objective of the Invention> An object of the present invention is to partially improve the above-mentioned prior art and to enable head positional deviation correction even in the absence of a positional deviation detection operation signal.

<Configuration of the Invention> The configuration of the present invention that achieves this object includes: a magnetic disk rotated by a spindle; a magnetic head that reads and writes data in close proximity to the surface of the magnetic disk; In a magnetic disk storage device comprising an actuator mechanism that moves the magnetic disk to a track position and a position control circuit that drives the actuator mechanism, a servo track is provided on at least one of the outside and inside of the data track area of the magnetic disk, and the magnetic head a positional deviation detection operation circuit that moves the magnetic head to the vicinity of the servo track, a positional deviation correction signal circuit that obtains a positional deviation correction signal based on the servo read signal read to the magnetic head, and a storage circuit that stores the positional deviation correction signal. a timer circuit that measures the elapse of a predetermined time; a timer sequence circuit that changes the predetermined time according to a predetermined sequence; and a timer sequence circuit that monitors the timer circuit when a seek command is input; Before executing the seek command, the magnetic head is moved to the vicinity of the servo track by the positional deviation detection operation circuit, the positional deviation correction signal is obtained and stored in the storage circuit, and then, at the same time as the seek operation is executed. The positional deviation of the magnetic head is corrected by the positional deviation correction signal obtained from the storage circuit, and when the prescribed time has not elapsed, the positional deviation of the magnetic head is corrected by the positional deviation correction signal obtained from the storage circuit at the same time as the seek operation is executed. The structural feature is to correct the.

<Embodiment> FIG. 1 is a block diagram showing an embodiment of the magnetic disk storage device according to the present invention, and FIG. 2 shows a timer sequence circuit 3.
8 is a block diagram of FIG. In FIG. 1, the same elements as those in the prior art shown in FIG. 4 are given the same reference numerals, and redundant explanation will be omitted. Also, since the provision of servo tracks on at least one of the outside and inside of the data track area of the magnetic disk is similar to the prior art shown in FIG. 3, a drawing of the magnetic disk is omitted.

In general, in a magnetic disk device, differences in thermal expansion occur among the components due to the ambient temperature and the heat generated by the device itself during operation, resulting in off-track. This off-track increases in proportion to the drive time of the device, but off-track due to self-heating of the device is even more noticeable after the power is turned on. In the present invention, the error with the outer or inner servo track is memorized during the first seek operation, and the positional deviation detection operation circuit is operated in short cycles according to the signal from the timer sequence circuit for a predetermined time when the device is started. After a certain period of time has elapsed, a timer circuit set to a relatively long time determines whether a specified period of time has elapsed (this specified period of time shall be determined in advance based on the characteristics of the magnetic disk drive), and the specified period of time is determined. If the elapsed time has elapsed, return to the outer or inner servo track and correct the positional deviation correction signal stored in the storage circuit, correct the positional deviation of the magnetic head based on the correction signal, and if it is within the specified time, it will be stored. The structure is such that the positional deviation of the magnetic head is directly corrected using the correction signal stored in the circuit.

In FIG. 1, when a new address is input to the address circuit 1 before a predetermined time has elapsed since the start of the device, the timer sequence circuit 38 is notified that a seek command has been input.

FIG. 2 shows a block circuit of the timer sequence circuit 38 shown in FIG. 1. After the power is turned on, the counter 40 and the flip-flop circuit 25 are reset by a reset signal, and the counter 41 is set. counter 40
is a binary counter, and the counter 41 is a counter having a parallel input/load function. These counters 40 and 41 receive, for example, 1/60 from the oscillation circuit 23.
Hz pulses are provided. As a result, the output of the counter increases every minute. This output is input to the inverter 28 to become a complement output, loaded by the seek command signal, and input to the counter 41. The counter 41 is counted up by a pulse from the oscillation circuit 23. Since the complement output from the counter 40 is input to the counter 41, the output of the counter 41 immediately after the seek command signal is input decreases with the elapsed time after the reset signal is input, and is counted up by the pulse from the oscillation circuit 23 and output. The time it takes for the carry (overflow) signal of the counter 41 to appear is delayed. The output of this counter 41 is input to and held in a flip-flop circuit 25, and passes through an AND gate 26 in response to a seek command signal to operate a positional deviation detection operation circuit 16 (see FIG. 1). Therefore, when the device is powered on, the contents of the storage circuit are frequently rewritten based on signals from the positional deviation correction signal circuit, and corrections are also frequently made for each seek command. In this timer sequence circuit 38, the number of times the positional deviation detection operation circuit is operated gradually decreases as time passes.

Reference numeral 27 denotes a monitoring circuit that monitors the number of counters 40, stops outputting from the timer sequence circuit to the positional deviation detection operation circuit after a certain period of time has elapsed, and operates the timer circuit 17. In the timer sequence circuit 38 and the timer circuit 17, if the seek command has passed a specified time since the previous seek command (in the timer sequence circuit, this specified time increases as time passes), the position shift detection operation circuit is driven and the servo is activated. The magnetic head 11 is positioned on the track, and a new positional deviation correction signal is input to the storage circuit 2 via the positional deviation correction signal circuit 3.

Thereafter, a normal seek operation is performed, and a correction signal is obtained from the memory circuit 2 to correct the position of the magnetic head. If the specified time has not elapsed since the previous seek command, the positional deviation correction signal is not corrected and only the normal seek operation is performed.

<Effects of the Invention> As specifically explained above in conjunction with the embodiments, according to the present invention, the elapse of time from the previous seek operation is monitored every time a seek command is issued, and the specified time is determined to have elapsed. In addition, this operation is performed frequently while the self-heating effect at power startup is large, so off-tracking caused by the ambient temperature and the magnetic disk drive's own heat generation in the initial stage is also carefully prevented. be able to.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a magnetic disk storage device according to the present invention, FIG. 2 is a block diagram showing an embodiment of a timer sequence circuit used in the present invention, and FIGS. 3 and 4 are magnetic disk surfaces showing conventional examples. FIG. 2 is an explanatory diagram and a block diagram of FIG. DESCRIPTION OF SYMBOLS 1... Address circuit, 2... Memory circuit, 3... Positional deviation correction signal circuit, 4... Read/write circuit, 5
... Drive signal circuit, 6... Amplifier, 7... Actuator, 8... Position and speed signal circuit, 9...
Position detection mechanism, 10... Position control circuit, 11... Magnetic head, 12... Magnetic disk, 13... Spindle, 14... Spindle drive mechanism, 15... Sector detection mechanism 17... - Timer circuit, 18... Outer servo track, 19... Data track area, 20.
...Inner servo track, 21...sector slot,
22... Index slot, 23... Oscillation circuit, 25... Flip-flop circuit, 26... AND gate, 27... Monitoring circuit, 28... Inverter,
38... Timer sequence circuit, 40... Binary counter, 41... Counter with parallel input/load function

Claims (1)

[Claims] A magnetic disk rotated by a spindle, a magnetic head that reads and writes data close to the surface of this magnetic disk, an actuator mechanism that moves this magnetic head to a desired track position, and a position that drives this actuator mechanism. A magnetic disk storage device comprising a control circuit, wherein a servo track is provided on at least one of the outside and inside of a data track area of the magnetic disk, and a positional deviation detection operation circuit that moves the magnetic head to the vicinity of the servo track; a positional deviation correction signal circuit that obtains a positional deviation correction signal based on a servo readout signal read to the magnetic head; a storage circuit that stores the positional deviation correction signal; a timer circuit that measures the elapse of a specified time; a timer sequence circuit that changes according to a predetermined sequence; and a timer sequence circuit that monitors the timer circuit or timer sequence circuit when a seek command is input, and detects the positional deviation before executing the seek command after a specified time has elapsed. moving the magnetic head near the servo track by an operating circuit, obtaining the positional deviation correction signal and storing it in the storage circuit;
Thereafter, the positional deviation of the magnetic head is corrected by a positional deviation correction signal obtained from the storage circuit at the same time as the seek operation is executed, and when the prescribed time has not elapsed, the positional deviation obtained from the storage circuit is corrected at the same time as the seek operation is executed. A head position deviation correction method characterized by correcting the position deviation of a magnetic head using a correction signal.