JPH01286185A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To correct the output of a driving circuit for the actuator of a magnetic head based on position data at two positions on a data recording plane and to accurately perform the positioning of the magnetic head on another disk plane by calculating misalignment between a disk having the data recording plane and the disk having a servo plane from the above data. CONSTITUTION:The CPU11 of a control system in a magnetic disk device supplies an analog control signal to move the magnetic head to a targeted position based on the travel distance of the magnetic head recognized by pulses inputted to an UP and a DOWN terminals to the driving circuit 16 of the actuator 10. Also, a driving signal from the circuit 16 receives correcting by a signal from a misalignment control circuit 14 at a deviation detecting point 17, and it is supplied to the actuator 10. Next, prescribed values are attached on a cylinder on which is recorded the servo data of the most significant disk D4 setting an index pulse and a sector signal as reference, and two kinds of signals deviated by a prescribed position from the center position to the outer side and inner side of the cylinder, respectively are set.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic disk device, and in particular to a magnetic disk device in which the positioning of a magnetic head is controlled by servo data written on one surface of a plurality of disks. This relates to disk devices.

``Prior Art'' The 10th magnetic disk device is widely used as a random access file for computer systems.
As shown in the figure, a plurality of disks 3 are concentrically attached to the shaft 2 of a spindle motor l serving as a drive source, and data is written and read on the recording surfaces D0 to Ds of each disk 3 by a magnetic head. A method using H0 to H6 is adopted. In this magnetic disk device, one of the plurality of recording surfaces (D,) is used as a servo surface, and the magnetic head H0
A system is adopted in which the positions of the other magnetic heads H0 to H1 are collectively controlled based on servo data read by the magnetic heads H0 to H1.

``Problem to be Solved by the Invention'' By the way, the above method requires that the data track positions of the servo surface and the other recording surface ~D match, as shown in Fig. 1θ. Assuming that the magnetic head Ha-HI is arranged along a reference line (indicated by the dashed line C in the figure) parallel to the central axis of the disk, the position data of the magnetic head H0 is Since this is intended to control the positions of the other magnetic heads Hl-Hs based on the magnetic heads Hl-Hs, as shown in FIG. Therefore, the reference line that should be at the position shown by the symbol C in the figure is the symbol C.
If the surface is tilted as shown by ', a deviation as shown by X in the figure will occur, and the track positions of the servo surface and the other surfaces D1 to D will not match, making accurate positioning control impossible. is possible.

As a conventional technique for solving the above problem, for example, the technique described in Japanese Patent Publication No. 54-15207 is known, and according to this technique, the lowermost surface and the uppermost surface of a plurality of disks are used as servo surfaces. Using this method, the inclination of the axis can be determined from the values of both servo disks, and based on this inclination, the positional deviation of each head can be corrected.

However, since this technology requires multiple servo surfaces, data recording capacity is unavoidably sacrificed, and control is complicated as it is necessary to constantly process multiple servo data. C that constitutes the control system
As the PU is required to have a large capacity, it is inevitable that the access time will be long.

The present invention was proposed in view of the above circumstances, and aims to reduce the load on the control system due to servo data processing and shorten access time.

"Means for Solving the Problem" In order to achieve the above object, the present invention provides a magnetic recording surface of a plurality of concentrically supported disks, each of which has a plurality of concentric circles having the same center as the disk. A servo surface is provided along which data indicating the position from the center of the concentric circle is recorded, and a drive circuit for an actuator for moving the magnetic head is provided in order to match the position data read from the servo surface with the position data of the target point. In the magnetic disk drive, a data recording surface on which data is concentrically recorded at positions corresponding to at least two concentric circles on the servo surface is provided on a disk different from the disk having the servo surface, A deviation calculating means is provided for detecting the amount of deviation in the surface direction between the servo surface and the data recording surface from the data of the concentric circles at the same position read from the servo surface and the data recording surface, respectively, A correction means is provided for correcting the output of the drive circuit according to the amount of deviation, and the sampling period for detecting deviation of the deviation calculation means is set to be longer after a predetermined period of time has elapsed from activation of the disk than before. It is something.

"Operation" With the above configuration, from the position data at two positions on the data recording surface, the disk having the data recording surface,
The magnetic head is moved based on the data from the servo surface by being able to calculate the positional deviation with the disk with the servo surface, and based on this data, correcting the output of the drive circuit of the magnetic head actuator. can be accurately positioned on other disk surfaces as well. In addition, by setting the sampling of the deviation amount to be short immediately after the disk starts, and long after a certain period of time has passed, fine adjustments can be made when the internal temperature is unstable immediately after starting, and after the internal temperature has stabilized. It can be maintained almost constant.

"Embodiment" Hereinafter, an embodiment of the present invention will be described with reference to flash screens. In the figure, parts common to the conventional example are given the same reference numerals to simplify the explanation.

FIG. 1 shows the configuration of a magnetic head control system.

In the magnetic disk drive of this embodiment, as in the conventional example, three disks 3 are provided on the shaft 2 of a spindle motor l, and one of the six surfaces of these disks 3 is made entirely of a servo surface. As well as recording servo data indicating the position of each cylinder (track),
The configuration is such that predetermined data is recorded using the other surfaces ~D as data surfaces. In addition to the above data, the uppermost recording surface D4 includes a servo surface,
A part of the servo data recorded in j2 corresponds to alignment servo data (for example, two pieces of servo data indicating positions corresponding to the innermost and outermost cylinders, respectively).

On the other hand, the magnetic heads H1 to H4 that respectively access the respective disks are driven by, for example, voice coil motors, DC
They are moved together by an actuator IO driven by a motor or the like.

The control system of the magnetic disk device is provided with a CPU 11'. The CPU II operates according to the program written in the ROMI2, and
, timer, D/A converter, A/D converter, ■"
It has functions such as RQ.

The CPU II supplies a control signal to the drive circuit 13 of the spindle motor 1, and also receives a feedback signal supplied from the spindle motor 1 via the drive circuit 13 via the IRQ input terminal to drive the spindle motor 1. The speed of the motor 13 is controlled.

Further, the magnetic heads H6 to H1 are driven by the actuator 1 by a drive circuit 13 controlled by an analog signal supplied via a D/A converter provided in the CPU II.
By driving 0, it can be moved along the disk surface.

Then, the magnetic head H1 reads the position of the cylinder (track) corresponding to that position from the servo surface and supplies it to the positional deviation control circuit 14.

Further, the positional deviation control circuit 14 determines the head movement direction from the servo data read from the magnetic head H1, and depending on the determination result, the UP input terminal of the CPU II or the DOWN
Supplying a number of pulses corresponding to the moving distance to the N input terminal,
The CPU II recognizes the moving distance of the magnetic head based on the pulse count value. Magnetic heads H0 to H provided on data recording surfaces 00 to D;
2 is a head switching circuit 1 operated by CPU II;
5, the servo data written using cylinders on a part of these data recording surfaces (D4 in this embodiment) is transferred to the position reproduction/recording control circuit 14 or data processing as necessary. It is designed to supply to the circuit (path shown).

Furthermore, the CPU II supplies an analog control signal to the drive circuit 16 of the actuator 10 via the D/A converter in order to move the magnetic head to the target position based on the movement distance of the magnetic head recognized from the pulse input to the UP1DOWN terminal. It is supposed to be done. In addition, the drive circuit 16
At the deviation detection point 17, the drive signal output from
After being corrected by a signal from the positional deviation control circuit 14, it is supplied to the actuator 1o.

Next, we will explain the recorded contents of the cylinder (data track) in which servo data is recorded on the recording surface of the uppermost disk. Data was written alternately from the center of the cylinder to the outer side (outer shoulder side of the disk) and the inner side (inner circumferential side of the disk), each with a 7 μm shift (in total, 42 letters were written per revolution). a)

It is composed of two types of signals: b.

In addition, the cylinder in which the servo data of the above pattern is written (hereinafter referred to as the reference cylinder) is located two cylinders and one minute further outward from the outermost cylinder CYLO used for data recording, as shown in Figure 3. (CYL-2) and the innermost cylinder CY
Lmax (corresponds to CYL931, which is 931 cylinders away from the CYLO in this example) and 3 cylinders further inward from Lmax (CYL931).
4) and are used as reference cylinders REFO and REF 1, respectively.

In the reference cylinder, when the center positions of the cylinder with the corresponding number on the servo surface and the magnetic head match, the signals a and b are read out at the same level, and the position of the magnetic head is on the outer side. If the deviation is toward the inner side, the signal a will be read out, and if the deviation is toward the inner side, the signal b will be read out at a higher level as the amount of deviation increases. Therefore, the servo at the position corresponding to the reference cylinder When the data is read out, the position shift control circuit 14 compares the levels of both signals a and b, thereby controlling the servo control on the data recording surface (in the case of the embodiment, the top DI) with the reference cylinder. It is possible to calculate the amount of positional deviation with respect to the surface.

Note that the absolute value of the deviation in REFO is Yo, REFI
Let Y be the absolute value of the deviation in any cylinder (CYLn) between these
Since there is a geometrical relationship as shown in FIG. 4, it can be calculated as follows.

Furthermore, in the case of the embodiment, if the error Yn detected on the uppermost recording surface is known, then the data surface D0 in the middle thereof is known.
The amount of deviation in the n-th cylinder of ~D is proportionally distributed by the distance h0~ha (expressed as hN) from the servo surface to each data surface, ~D; That is, it can be calculated by Y n X h N/h 4 .

Next, the contents of the above-mentioned shift detection and position correction processing are explained in the fifth section.
The flowcharts shown in FIGS. 9 to 9 will be explained below.

Seek operation SAI: When a seek command is issued, the seek destination cylinder number, sector number, and corresponding head number are calculated and selected according to the contents of the seek command.

SA2: Determine whether or not the seek destination cylinder number matches the cylinder in which the head is currently stopped, that is, whether or not there is a need to move it, and if necessary, select S.
If there is no need to proceed to A3, proceed to SA4.

SA3: Seek to the target cylinder.

SA4: Determine whether or not the count value of the sampling timer that has passed the period of deviation detection exceeds the predetermined sampling period, and if it does, proceed to SA5.
If it does not exceed the limit, proceed to SA6. In addition, in the embodiment, the elapsed time from the start of the magnetic disk is calculated by the CPU.
It is measured by a built-in timer, and the sampling period is set to be gradually longer as the elapsed time increases.

SA5: A new amount of deviation is detected in order to cope with a change in the amount of deviation due to a predetermined time or more elapsed since the previous sampling. That is, the head switching circuit 15 supplies the output of the magnetic head H to the position reproduction/recording control circuit 14.
is operated, the servo data of the reference cylinder REF0.1 is read by the magnetic head H4, and from the read servo data of the reference cylinder REF0,1, the amount of deviation Yn in the data surface D4 is determined by the method described above. , calculate the amount of deviation in the corresponding cylinder of any data surface to be accessed.

SA6: The output of the magnetic head H1 is switched to be supplied to a predetermined data processing circuit, and the data read from the servo surface Ds is changed to the amount of deviation (depending on the sampling time, the amount of deviation found in SA5, or The actuator 10 is controlled to move a predetermined magnetic head to a target cylinder to access for reproduction or recording.

In addition, when the same cylinder is accessed continuously, the access starts without going through a seek operation, so in this case, as shown in FIG. 6, the output of the magnetic head H4 is At the same time as switching to the positional deviation control circuit 14, the sampling time is determined (5BI),
If the sampling time = 0 (if access is performed continuously), the amount of deviation is detected in the same manner as in SA5 (SB2), otherwise, the process directly proceeds to S83 and the process is performed as in SA6. Perform similar processing.

Furthermore, in the above embodiment, the amount of deviation of each magnetic head is calculated on the assumption that the amount of deviation increases linearly between the bottom head H1 and the top head H4.
Assuming a non-linear case, or in order to perform more precise misalignment correction, other magnetic heads Ho, Hs, Ha
It is also effective to obtain the amount of deviation at three locations. In this case, the reference data planes D @ , D s , and D 4 have alignment servo data written in them as shown in FIGS. 2 and 3, respectively. In addition to providing a cylinder, SA5 or SB2 in Figures 5 and 6
In place of the deviation amount detection process that was executed in the seventh
The process shown in the figure may be performed.

That is, each magnetic head is moved to seek to REFO (S01), and first, the head switching circuit 1 is moved to supply the data of the magnetic head H6 to the position reproducing/recording circuit 14.
5 is operated (SC2), and the amount of deviation in REFO of 'data side' is detected (SC3). Next, switch to the magnetic head H1 (SC4) and REFO the data surface.
After detecting the amount of deviation in (SC5), the magnetic herad H
4 (SC6), and detect the amount of deviation in the data surface (SC7). Furthermore, each magnetic head is moved to seek to REFI (SC8), and this
In F1, similarly to SC2 to SC7, the displacement of the magnetic heads H11, H3+H4 is detected (SC9 to SC14), and the magnetic head is used to seek the original cylinder, that is, the cylinder that is commanded to be accessed for reproduction or recording. Move the head. (SC15) Note that the amount of deviation of data surfaces other than data surfaces D, Ds, and Da for which the amount of rubbing was measured by the above SCI~5C15 can be calculated as follows from the amount of deviation detected on other data surfaces, for example. This value can be used as correction data for the amount of deviation on each recording surface.

O data surface D1 I/2 of the amount of deviation detected in D. 0 Data side.

t/ of the sum of the deviation amounts detected in D o D a
Furthermore, in the shift detection process, the process of selecting the shift amount to be used for control from the measured value of the shift amount is as shown in FIG.

SDI: The amount of deviation is detected by SEI to SE4, which will be described later.

Sn2: Correct the position of the magnetic head based on the detected amount of deviation.

Sn3: Calculate the amount of deviation again in the same way as SDI.

Sn4: Determine whether the detected amount of deviation is within ±0.5 μm of the reference range, and if No, proceed to Sn5; if YES, proceed to Sn2.

Sn5: Proceed to Sn2 on the condition that SD1 to SD4 have been repeated a predetermined number of times (5 times).

506: Load the amount of deviation detected at Sn3 as a correction value.

Furthermore, the process of detecting the amount of deviation for a certain data plane, which is performed in the SDI, is as shown in FIG.

SEI: Proceed to the next SB2 on condition that a sector signal is input that triggers reading of reference data.

SB2: Read the servo data written in the external fli reference cylinder.

SB3: Move the magnetic head to read the servo data written in the inner reference cylinder.

SE4: Calculate the amount of deviation in the seek destination cylinder from both amounts of deviation.

As described above, the data surface D4 (or D) at the position corresponding to a specific cylinder on the servo surface.

) The output of the drive circuit 16 of the actuator IO can be corrected in accordance with the amount of positional deviation determined from the servo data.

In the case of the embodiment, focusing on the fact that the amount of positional deviation changes with temperature, the sampling period for deviation detection was gradually lengthened over time from the start of the magnetic disk. The time when the temperature of is almost in a steady state (as determined by temperature measurement experiments, etc.) is the boundary, and before that time, a short sampling period is adopted, and after that, a long sampling period is adopted.
The sampling time may be changed in two stages.

In addition, if there is a temperature change due to the temperature change of the magnetic disk device, or if the temperature is below a certain level (and there is a possibility of temperature rise), the sampling time should be shortened, and if the temperature change is more than a specified value, the sampling time should be shortened. In this case, the sampling time may be increased.

Furthermore, the cylinders to which alignment servo data are to be written do not necessarily have to be provided at two locations on the inner periphery and the outer periphery as in the embodiment, but may be provided at more locations. By performing detection at more locations, it is possible to accurately correct even non-uniform slippage.

"Effects of the Invention" As is clear from the above explanation, according to the present invention, a position data of a disk having the data recording surface and a disk having the servo surface are determined from position data at two positions on the data recording surface. The deviation can be calculated, and by correcting the output of the drive circuit of the magnetic head actuator based on this data, the magnetic head that is moved based on the data from the servo surface can also be adjusted to the other disk surface. Accurate positioning is possible.

(b) Since only a small number of cylinders on the recording surface other than the servo surface are used for servo, positional deviation can be corrected with almost no effect on the recording amount.

C By setting the sampling of the deviation amount to be short immediately after the disk is started and long after a certain period of time has passed, fine adjustments can be made when the internal temperature is unstable immediately after the disk is started.
After the internal temperature is stabilized, it is maintained at a substantially constant level, so that detection of the amount of deviation can be kept to the minimum necessary and an extension of access time due to deviation adjustment can be prevented.

It has various effects such as.

[Brief explanation of the drawing]

1 to 9 show an embodiment of the present invention,
Figure 1 is a block diagram showing the configuration of the control system, Figure 2 is a diagram showing the contents of data recorded on the reference cylinder, Figure 3 is a diagram showing the position of the reference cylinder on the data recording surface, and Figure 4 is a diagram showing the position of the reference cylinder on the data recording surface. A chart showing changes in the amount of deviation corresponding to the cylinder position, Fig. 5 is a flowchart of the general deviation detection process as a whole, and Fig. 6 shows the process when the same cylinder is accessed continuously.
0-chart, FIG. 7 is a flowchart of the process of sequentially detecting the deviation of each head, FIG. 8 is a flowchart of the process of selecting the amount of deviation from a plurality of measured values for each head,
Fig. 9 is a flowchart for measuring the amount of deviation in each cylinder, and Figs. 1θ and 11 show the positions of the disk and head in a normal state and a state in which a positional deviation has occurred in a magnetic disk drive on a boat, respectively. FIG. 3 is a front view showing the relationship. l... Spindle motor, 2... Axis,
3...Magnetic disk, 10...Actuator, 11...CPU, 13...
Drive circuit, 14...Position shift control circuit, 15.
...Head switching circuit, 16... Drive. Circuit, 17... Deviation detection point (correction means), D,
... Servo surface, D0-D, ... Recording surface, Hs ... Magnetic head, H0-H6 ...
・Magnetic head.

Claims (1)

[Claims] A servo surface formed by recording, on one of the magnetic recording surfaces of a plurality of concentrically supported disks, data indicating the position from the center of the concentric circles along each of a number of concentric circles having the same center as the disk. In a magnetic disk drive in which a drive circuit for a magnetic head moving actuator is controlled to match position data read from the servo surface with position data at a target point, a magnetic head is provided in at least two concentric circles on the servo surface, respectively. A data recording surface on which data at a corresponding position is concentrically recorded is provided on a disk different from the disk having the servo surface, and from data about concentric circles at the same position read from the servo surface and the data recording surface, respectively. A deviation calculation means for detecting the amount of deviation in the plane direction between the servo surface and the data recording surface is provided, and a correction means is provided for correcting the output of the drive circuit based on the deviation amount calculated by the deviation calculation means, A magnetic disk device characterized in that a sampling period for detecting a deviation of the calculation means is set longer after a predetermined time has elapsed since the start of the disk than before.