JPH01113977A - Track positioning method for magnetic disk device - Google Patents

Abstract

PURPOSE:To control a track positioning when the quantity of the dislocation of a track position is large by setting a difference between the level value of first or a second sine wave selected from the operating position information of an access motor and a level value as position dislocation information as track position error information. CONSTITUTION:The first sine wave of a cycle corresponding to the movement quantity twice as high as a track pitch and the second wave having the phase difference of about 1/4 cycle to the first sine wave are outputted according to an operating position as the operating position information of the access motor and the first sine wave or the second sine wave is selected according to the section of the quantity of the dislocation of the track position previously calculated as the track position dislocation information. Then, the access motor is driven so as to approach the track position error information according to the difference between the level value set corresponding to the track position dislocation quantity in the selected sine wave and the level value set as the track position dislocation information to zero. Thereby, the position dislocation above the track pitch can be corrected to position.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a track positioning method for a magnetic disk device.

(Prior Art) In a magnetic disk drive, a step motor, voice coil motor, Naoka motor, or the like is generally used as a drive source for accessing a magnetic head to a predetermined track position. A step motor has a slow access speed and is suitable for low-cost equipment, whereas a voice coil motor has a high access speed and is suitable for high-end equipment. DC motors are often used in intermediate-level equipment.

In the case of DC motors, an encoder is used at the same time to enable track-by-track movement and positioning to a defined track position. An encoder generally consists of a slit disk having a slit corresponding to the track pitch and rotating together with the motor shaft, and a photo sensor, and detects the rotation angle of the motor. Therefore, by controlling the rotation of the DC motor using an encoder, the magnetic head can be accessed to a predetermined track position.

In a magnetic disk drive, when there is a temperature change, a track position shift occurs between the track position of the magnetic disk and the position of the magnetic head due to differences in thermal expansion of each member. If this track position deviation is large, it will interfere with adjacent tracks and cause reading errors, so to prevent this, track position information is written on the magnetic disk and read out with a magnetic head. The amount of positional deviation between the motor rotation angle and the rotation angle of the motor by the encoder is calculated, and feedback is provided to the DC motor to correct the positional deviation amount so that the positional deviation disappears.

FIG. 2 is a block diagram of a conventional track positioning circuit.

In the figure, 1 is a magnetic disk, 2 is magnetic^, rad,
3 is the arm to which the magnetic head 2 is attached, 4 is the arm 3
This is an access motor consisting of a DC motor that drives the.

A capstan 5 is connected to the rotating shaft of the motor 4, and a flexible steel belt 6 with both ends fixed to the arm 3 is wound around the capstan 5, and when the motor 4 rotates, the magnetic head 2 moves. do. 7 is an encoder that outputs rotational position information of the motor 4, that is, operating position information P.

8 is an AD converter which converts the deviation information of the magnetic head 2 with respect to the track read by the magnetic head 2 into a digital value. As the deviation information, for example, two types of burst signals shifted by half a pitch centering on each track are written on the magnetic disk 1 as servo information, and when each servo information is read by the magnetic head 2. Values based on mutual amplitude ratios are used. 9 is a microb computer that calculates track position deviation information due to track position deviation when the magnetic head 2 is positioned at the track position and in a stable state based on the value of the AD converter 8, and converts it into an 8-bit digital value. Output. Then, the value is corrected from time to time according to changes over time. 10 is DA
The converter converts the track position deviation information calculated by the microcomputer 9 into track position deviation information C in an analog quantity. A subtracter 11 calculates an error signal E (rack position error information) based on the difference (CP) between the track position deviation information C and the operating position information P. 12
is an amplifier, 13 is a drive circuit, and error signal E is an amplifier 1.
Upon receiving this signal, the drive circuit 13 outputs an error signal E when the magnetic head 2 is finely adjusted to the track position.
The motor 4 is driven to bring the value closer to 0. When the error signal E becomes 0, the track position is balanced.

FIG. 3 is an explanatory diagram of the positioning operation by the circuit of FIG. 2. The operating position information P is a sinusoidal signal whose voltage changes between +Vm and -Vm according to the rotation angle of the motor 4. Levels Pn-1 and Pn of the intersection of this operating position information P and the O level.

The phase of P nil . . . corresponds to the presence of the magnetic head 2 on each track n-1, n, n+1 . . . when there is no track position shift. In this case, the motor 4 positions the track at this position. When a track position deviation occurs due to temperature fluctuation, for example, when the track position deviation amount is dl, the track position deviation information C is set to C1, and when it is d2, it is set to C2, and the operating position information P becomes Pl and P2, respectively. Track positioning is performed by controlling the rotation angle of the motor 4 for each phase.

(Problem to be Solved by the Invention) However, according to the above method, the value of the track position deviation information C varies from Cmax to Cll1 shown in FIG.
limited to the range of in. That is, greater than Cwax, Cmi
This is because the value P of the encoder 7 becomes unstable at the apex in the range smaller than n, and in the end, the range of track position deviation amount is from d wax to d min in the figure, which is ±1.
/2 track pitch or less. Therefore, if a track position shift of more than half a pitch occurs due to temperature fluctuations, this circuit cannot correct it. Therefore, since it is necessary to set the track pitch so that the track position deviation does not exceed half a pitch, there is a problem that the track density cannot be increased and the storage capacity cannot be increased.

In view of the above-mentioned problems, the present invention generates a specific composite wave for each stage of the positional deviation amount from the operating position information of the access motor, and converts the phase at which the level value of the composite wave becomes 0 to the phase exceeding the track pitch. It is an object of the present invention to enable track positioning control when the amount of track position deviation is large by arranging the track position over the entire range and positioning the track at the phase that becomes 0.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides mutual track position deviation information between the deviation information of the magnetic head with respect to the track read from the magnetic disk and the operating position information of the access motor. In a track positioning method for a magnetic disk device, track positioning is controlled by calculating track position error information and driving an access motor to bring track position error information based on the track position deviation information and operating position information closer to 0. consisting of a first sine wave with a period corresponding to twice the amount of movement of the pitch and a sine wave with a phase difference of about 1/4 period with respect to the first sine wave,
The positional deviation information includes a selection signal that selects the first sine wave or the second sine wave according to the classification of the track positional deviation amount, and a selection signal that selects the first sine wave or the second sine wave according to the classification of the track position deviation amount, and The selected first sine wave or second sine wave is determined by each level value of the phase corresponding to the amount of positional deviation.
In this track positioning method, the difference between the level value of the sine wave and the level value as the positional deviation information is set as track position error information.

(Function) According to the present invention, the first sine wave and the second sine wave are output as the operating position information of the access motor according to the operating position, and the track position deviation information calculated in advance is output as the track position deviation information. The first sine wave or the second sine wave is selected according to the amount classification, and a level value corresponding to the amount of track position deviation in the selected sine wave is set. The access motor is driven to perform track positioning control in order to bring track position error information based on the difference between the level value and the level value set as the track position deviation information closer to zero.

(Embodiment) FIG. 1 is a block diagram of a track positioning circuit showing an embodiment of the present invention.

In this figure, the same parts as in FIG. 2 are given the same reference numerals, and the different parts will be mainly explained below.

Reference numeral 7A denotes an encoder, which sets the phase θ when the magnetic head 2 is on the track at the reference temperature as 0, and sets the phase θ to 2 of the track pitch as the operating phase information of the access motor 4.
a first sine wave s1nθ with a period corresponding to twice the amount of movement;
A second sine wave 5 inches (θ-π/2) having a phase difference of 1/4 period with respect to the sine wave sin θ is generated.

9A is a microcomputer 9 that calculates the amount of track position deviation based on the deviation information of the AD converter 8, similar to the microcomputer 9 in FIG. It is output as a digital value of sine wave sin θ or sine wave sin (θ−
A selection signal S for selecting π/2) is output.

14 is a switch that selects each sine wave sinθ according to the selection signal S.
Alternatively, select sin (θ-π/2). 11A
is a subtracter, which calculates an error signal E (track position error information) based on the difference between the track position deviation information C and the selected operating position information consisting of sin θ or sin (θ−π/2), and outputs the error signal E (track position error information) to the amplifier 12. give to

Next, the operation of the circuit shown in FIG. 1 will be explained. FIG. 4 is an explanatory diagram of the operation of the circuit shown in FIG. 1.

In the same figure, a sine wave as operating position information,
Each level P n-1 where θ becomes 0, P n * P n
As in FIG. 3, the phase of il++ is the same as in FIG. 3 for each track n1. when there is no track position shift. n, n+1
...This corresponds to the fact that the magnetic head 2 is located above.

The microcomputer 9A has a track position shift ff1d.
However, when the phase dO corresponding to the level Pn in FIG. 4 becomes d win to d l1ax explained in FIG. Cl1 as track position deviation information C
Specify in to Cmax. And positional deviation information Cs
in, Cll1ax and sine wave sin (θ-π/4)
When it becomes d8 to d4 due to each positional deviation determined by the intersection with
(θ−π/2), and the positional deviation information C at this time
specifies Cakin to Cwax as above. In addition, in order to stabilize the position control when switching the switch 14,
In this embodiment, hysteresis is provided in the operation of the selection signal.

First, the track position deviation amount d is, for example, d shown in FIG.
a+ax, the track position deviation information C of the microcomputer 9A is Ca, and in this case, the sine wave sin
(θ-π/2) is selected and the selection signal S is at a low level. Then, the difference Ca -51n ( θ-π/2) becomes the error signal E, and when the level of sin (θ-π/2) reaches Pa, the error signal E becomes 0 and track positioning is performed.

When the track position deviation ff1d decreases from this state and the track position deviation information C reaches Cwin (indicated by level pb in the figure), the selection signal S becomes high level and the sine wave sinθ is selected, and the position deviation information C is Cc(sinθ
level Pc), and the error signal E becomes c c-
It is calculated by sin θ and positioned in the same way.

From this state, the track position deviation amount d increases,
Track position deviation information C is Cmax (level Pd in the diagram)
), the selection signal S becomes low level, the track position deviation information C becomes Ca, and the state returns to the initial state.

In this embodiment, the phase difference between the first sine wave and the second sine wave is set to π12, but it is not necessary to set it exactly to π12, and the amount of track position deviation shown in FIG. If the difference between d+in and d4 is set to be greater than π, that is, the track pitch, any amount of track position deviation can be accommodated.

(Effects of the Invention) As explained above, according to the present invention, even if a track position shift of more than the track pitch occurs due to temperature fluctuations, the track position shift is corrected and track positioning is performed. The density can be set to a high value, thus making it possible to increase the density of recording bits.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a track positioning circuit showing an embodiment of the present invention, FIG. 2 is a block diagram of a conventional track positioning circuit, FIG. 3 is an explanatory diagram of the operation of the circuit in FIG. 2, and FIG. 4 is a block diagram of a conventional track positioning circuit. FIG. 2 is an explanatory diagram of the operation of the circuit shown in FIG. 1; 1...Magnetic disk 2...Magnetic head 4...Access motor 7...Encoder 9A...Microcomputer 11A...Subtractor 14...Switcher Patent applicant Oki Electric Industry Co., Ltd.

Claims (1)

[Scope of Claims] Track position deviation information between the deviation information of the magnetic head with respect to the track read from the magnetic disk and the operating position information of the access motor is calculated, and the track position is based on the track position deviation information and the operating position information. In a track positioning method for a magnetic disk device in which track positioning is controlled by driving an access motor to bring position error information close to 0, the operating position information is a first sine of a period corresponding to a movement amount twice the track pitch. and a sine wave having a phase difference of about 1/4 period with respect to the first sine wave, and the positional deviation information is composed of the first sine wave or the second sine wave depending on the classification of the track position deviation amount. a selection signal for selecting a sine wave, and each level value of the phase corresponding to the positional shift amount in the selected first sine wave or second sine wave, and the selected first sine wave Alternatively, a track positioning method for a magnetic disk device, characterized in that a difference between a level value of the second sine wave and a level value as the positional deviation information is set as track position error information.