JPS6358683A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To perform quick shift of a head by providing the reference servo tracks to plural divided information areas in response to synchronism of the output signal of a head position detecting means to store the off-track value and shifting the servo tracks for matching by an amount equal to the head shift value after positioning in case of head shifting. CONSTITUTION:A microprocessor 8 changes over a switch 13 with application of a power supply and subtraction 11 is performed between the speed reference value and the frequency/voltage conversion value of the output of an optical sensor 2. Then the error voltage is applied to an actuator motor 6 and the track pulses are counted to shift a magnetic head 3 into a target reference servo track. Then the witch 13 is hanged over to produce the position reference value and one of 4-phase output signals of the sensor 2 is selected (7) and undergoes subtraction9. Thus a motor 6 is revolved and halted at error voltage O (designated track). Then the servo signal of a magnetic disk 1 is detected by the head 3 and processed (15) and an actual difference is calculated between a reference servo track and a center. The off-track value stored previously is corrected for fine adjustement of the head 3. As a result, the shift time of the head 3 is shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic disk device suitable for use in controlling the position of a magnetic head with respect to a target data track.

[Summary of the invention]

The present invention provides a magnetic head position detecting means that roughly positions a magnetic head with respect to a target data track using a head position detection means that outputs a periodic output signal, and then controls the position of the magnetic head using a reference servo signal recorded on a magnetic disk. In a disk device, a magnetic disk is divided into a plurality of data areas, and a plurality of reference servo tracks corresponding to the periodicity of an output signal of a head position detection means are provided in each of these data areas so as to form a circumference. , an off-track amount is stored in relation to a reference servo track for each data area, and when the magnetic head is moved, the magnetic head is shifted by the stored off-track amount after positioning by the head position detection means. By just tracking the magnetic head, the moving time of the magnetic head can be shortened, and data can be written on the entire circumference of the data track.

[Conventional technology]

Conventionally, various methods have been proposed for the servo system to control the position of the magnetic head with respect to the target data track.
For example, a sector servo method and a servo surface servo method are examples.

In the sector servo system, as shown in Figure 2 of JP-A-51-81603, a large number of data tracks are arranged on a magnetic disk, and a servo track is arranged in one section on the circumference of the data track. It is arranged so that it exists.

In addition, the servo surface servo method is disclosed in Japanese Patent Application Laid-Open No. 51-81603.
As described in FIG. 1 of the publication, servo tracks are arranged over one gold surface of one of a plurality of magnetic disks stacked at predetermined intervals.

[Problem that the invention seeks to solve]

However, in the case of the sector servo method, since control is applied once for each sector, rotational waiting time is required until the sector arrives and the servo signal is read, which has the disadvantage that the head movement time becomes longer. Since the servo track is arranged in one section on the circumference of the data track, data cannot be written all around the trunk, so it was necessary to make room for the servo pattern.

Furthermore, in the case of the servo surface servo method, one side of one magnetic disk is entirely used for the servo track, which has the disadvantage that the efficiency of using the magnetic disk is low when viewed from the data track.

This invention was made in view of these points, and it is possible to shorten the head movement time, write data on the entire circumference of the track, and use the entire surface of the magnetic disk exclusively for the servo track. The present invention provides a magnetic disk device with excellent utilization efficiency.

[Means for solving problems]

A magnetic disk device according to the present invention is a magnetic disk device in which a head position detecting means (2, 5) roughly positions a magnetic head (3) with respect to a target data track. A reference servo track TR is provided in these data regions so as to form a circumference, and an off-track amount is determined for each data region in relation to the reference servo track. When the magnetic head is moved, the magnetic head is shifted by the stored off-track amount after positioning by the head position detection means.

[Effect]

A magnetic disk (1) is divided into a plurality of data areas Z1 to Zn each consisting of a plurality of data tracks. A reference servo trunk TR is provided for each of these data areas so as to form a circumference. Then, the microprocessor (8) calculates the off-track amount in relation to the reference servo track for each data area, that is, the difference between the position of the magnetic head at which the output of the head position detection means becomes zero and the position when the position is determined by the servo signal. stored in memory. When the magnetic head is moved for reading/writing, the head position detection means positions the magnetic head so that the output becomes zero, and then the off-track amount stored in the memory as described above is used. The magnetic head is shifted to just track. As a result, the magnetic head can be accurately positioned with respect to the data track, the moving time of the magnetic head can be shortened, and data can be written on the entire circumference of the track, thereby improving the utilization efficiency of the magnetic disk.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail based on FIGS. 1 to 4.

FIG. 1 shows the circuit configuration of this embodiment, in which (1) is a magnetic disk as a recording medium,
As shown in FIG. 2, all the tracks of this magnetic disk (1) are divided into n data areas Z1.22...Zn, each consisting of a plurality of data tracks, and
Servo-dedicated reference servo tracks TR□, TR2...Tttn are provided in the respective data areas ZL, Z2...Zn, which are separate from the data tracks on which the position detection signals are generated.

Now, the optical sensor (2) is set to 9 as shown in FIG.
Four-phase output signal SA with a phase shift of 0°.

Assuming that s day, SC, and so are generated, and each signal has a period of 4 tracks, a reference servo trunk TR is provided in each data area as shown in FIG. It consists of two tracks: and ■.

Data tracks TDA+TDRr'T''oc and Too are provided on both sides of the reference servo track TR.These TDA, 'raB.

TDC and TDD correspond to the four-phase output signals S A I S B + S c and S p from the optical sensor (2), respectively, and among the zero cross points to the signal S, the point on the upper right side is the data track TDA. (TDA here does not indicate one data track, but indicates a group of multiple tracks repeated in a four-track cycle.) Similarly, the signal SR+SC corresponds to the track center.

Among the zero cross points of SO, the points upward to the right correspond to the track centers of data tracks T os , T oc , and T oo , respectively. Note that the standard servo track TR is ■.

The track width of ■ is data track T DA - T DD
The width of the track is approximately equal to the width of the track.

(3) is a magnetic head that is attached to the arm (4) together with the optical sensor (2) and scans each track of the magnetic disk (1), (5) is an optical scale, and (6) is an actuator motor. The optical sensor (2) includes a plurality of optical sensors (2), in this case 4 (flit) light receiving elements (not shown) and reticle elements (not shown) provided in front of the light receiving elements (not shown) each having a phase difference of 90°.
(not shown), and a corresponding optical scale (
5), one light emitting element (not shown) is provided on the opposite side. By moving the arm (4) by the motor (6), the optical sensor (2) attached to it moves along the optical scale (5), and as the optical sensor (2) moves, magnetic A head (3) moves over a magnetic disk (11).

As the arm (4) moves, the slits of each reticle element and the slit of the optical scale (5) match,
The mismatch is repeated, and the above-mentioned output signals S^, SR, SC, and 311 are outputted from the four light receiving elements.

The output of the optical sensor (2) is supplied to an optical signal processor (7), undergoes signal processing such as amplification, and is supplied to a microprocessor (8). This microprocessor (8
), each time the magnetic head (3) scans one track,
pulse signals are supplied from the optical signal processor (7).

Also, the output signal of the optical signal processor (7) is
The signal is supplied to one input side of the subtracter (11), and is also supplied to the frequency-voltage conversion circuit (10), where the frequency signal is converted into a voltage signal and supplied as speed information to one input side of the subtracter (11). Ru.

(12) is a D/A converter, in which the output signal from the microprocessor (81) is converted from a digital signal to an analog signal, and this converted analog signal is sent to the subtracter (9) and (11). ) is supplied to the other input side of the

Subtractors (9) and (11) perform subtraction for both people,
A position control signal is generated from the subtracter (9), and a position control signal is generated from the subtracter (1).
1)'' generates speed control signals and supplies them to contacts a and b of the switch circuit (13), respectively.

The switch circuit (13) is switched by a position/speed switching signal from the microprocessor (8), and when the switch circuit (13) is connected to the contact a side, the operation mode becomes position control mode; Then, the operation mode becomes speed control mode.

Each control signal passing through the switch circuit (13) is supplied to a motor drive circuit (14), and this motor drive circuit (14)
The drive of the motor (6) is controlled by a drive signal from.

Further, while the magnetic head (3) is scanning the reference servo track, the servo signal is supplied to the servo signal processor (15),
Here, the difference between the signals detected from both tracks ■ and ■ of the reference servo track is detected, the analog signal is converted into a digital signal by the A/D converter (16), and the signal is supplied to the microprocessor (8). .

Next, the operation of the circuit shown in FIG. 1 will be explained.

When the power is turned on, first the reference servo tracks 'r, 1. 'r,. , . . . Seek commands to TRn are sequentially output from the microprocessor (8), and the switch circuit (13) is connected to the contact side by the position/speed switching signal from the microprocessor (8).
It is considered to be speed control mode. A speed reference value is given to the D/A converter (12) by the microprocessor (8), and the corresponding output signal from the D/A converter (12) is sent to the other side of the subtracter (11). Supplied to the input side. At the same time, the output signal of the optical sensor (2) is sent to the optical signal processor (
7) to a frequency-voltage conversion circuit (10), and the speed signal from this conversion circuit (10) is supplied to a subtracter (11).
) and is subtracted from the signal corresponding to the previous speed reference value. The error voltage is then supplied to the motor (6) via the motor drive circuit (14) to rotate it, thereby bringing the magnetic head (3) attached to the arm (4) closer to the reference servo track. . Then, track pulses are sequentially counted to drive the magnetic head (3) into the target reference servo track.

Next, the switch circuit (13) is switched to the contact a side by a position/velocity switching signal from the microprocessor (8), and the position control mode is set. Microprocessor (8
) gives a position reference value to the D/A converter (12), and the corresponding D/A conversion! The output signal from (12) is supplied to the other input side of the subtracter (9), and at this time, O is initially given as the position reference value. At the same time, the output signal of the optical sensor (2) is transmitted to the optical signal processor (
7) to one input side of the subtractor (9);
The signal corresponding to the previous position reference value is subtracted, but the optical signal processor (7) selects one output signal from among the four-phase output signals from the optical sensor (2). .

The error voltage is then supplied to the motor (6) via the motor drive circuit (14) to rotate it, which moves the magnetic head (3) attached to the arm (4) and reduces the error voltage. The magnetic head (3) is made to stand still on the reference servo track where the seek command was issued, which is where the magnetic disk (1) and the arm (4) reach zero.

Due to changes such as temperature expansion of the optical scale (5), it does not match the track center.

After that, the servo signal recorded on the magnetic disk (11) is detected by the magnetic head (3), and the servo signal processor (15
), the signal is processed by the A/D converter (16), the analog signal is converted into a digital signal, and the signal is sent to the microprocessor (8) to calculate the deviation of the actual reference servo track from the track center. .

The microprocessor (8) detects the position of the optical center, that is, the position of the magnetic head (3) where the output of the optical sensor (2) becomes zero, and the reference servo track (■, ■), which is the position when positioning is performed using the servo signal. The off-track amount, which is the difference from the position of the magnetic head (3) where the output is zero, is determined and stored in the memory (not shown) of the microprocessor (8).

At the same time, the off-track amount is calculated for the reference servo track of all n data areas, and the microprocessor (8
) in memory.

Optical sensor (2) when seeking for read/write
After moving the magnetic head [3] to the specified data track, the output signal from the controller determines which data@ area from 1 to n the track after movement belongs to, and which period of the 4-track period it is in. , calculated by the microprocessor (8),
The corresponding off-track amount is read out from the off-trunk amount stored in advance in the memory, and the position reference value for the off-track amount is given from the microprocessor (8) to the D/A converter (12), and the D/A converter (12) is The output signal of the converter (12) is supplied to the motor drive circuit (14) via the subtracter (9) and the contact a side of the switch circuit (13), and the motor (6) is rotated by the drive signal. By slightly shifting the arm (4), the magnetic head (
3) Move and just track.

Further, since the amount of off-track changes due to changes in ambient temperature, etc., the amount of off-track stored in the memory of the microprocessor (8) is updated by accessing the reference servo track again in the following two cases.

■ When attempting to seek to the desired data transaction,
If the data area to which the data track belongs has not been sought for more than a certain period of time in the past, access the reference servo track to which the target data trunk belongs, update the off-track amount to be stored from the servo signal, and then retrieve the target data. The magnetic head (3) is moved to the track, and the magnetic head (3) is slightly shifted by the updated off-track amount to just track.

■ If the positioning has been on the same data track for a certain period of time or more, access the reference servo track in the bending data area of that data track and return to the data track where the off-track amount was updated based on the servo signal.
The magnetic head (3) is slightly shifted from the position determined by the center of the optical signal by the updated off-track amount to just track.

In addition, in order to update the off-track amount on the reference servo track of one certain data area, it is sufficient to access the reference servo track in one certain data area, calculate the off-track amount from the servo signal, and update it. .

Note that in the above embodiment, four light receiving elements are provided to obtain four-phase output signals from the optical sensor, but two light receiving elements are provided and the remaining two output signals are The output signal of the light receiving element may be obtained via an inverter.

In addition, when a plurality of magnetic disks are provided, a reference servo track may be provided on each magnetic disk as described above, or, for example, a reference servo track may be provided only on the magnetic disk arranged in the center, and the remaining upper and lower magnetic disks may be provided with a reference servo track. The data trunk of the magnetic disk may be accessed by using a reference servo track of the magnetic disk located in the center.

〔Effect of the invention〕

As described above, according to the present invention, when moving the head, the pre-stored off-track amount is corrected to achieve just trunking, so the time required to read the servo signal can be eliminated, and the head movement time can be speeded up. can do. Furthermore, since there is no servo pattern on the data track, data can be written over the entire circumference, making it possible to improve the utilization efficiency of the surface of the magnetic disk.

[Brief explanation of the drawing]

FIG. 1 is a circuit configuration diagram showing an embodiment of the present invention, and FIGS. 2 to 4 are diagrams for explaining the invention. (1) is a magnetic disk, (2) is an optical sensor, (3) is a magnetic head, (5) is an optical scale, (6) is an actuator motor, (7) is an optical signal processor, and (8) is a microprocessor. , +9), (11) is the subtractor, (1
0) is a frequency-voltage conversion circuit, (12) is a D/A converter, and (13) is a switch. The child circuits include (14) a motor drive circuit, (15) a servo signal processor, and (16) an A/D converter.

Claims (1)

[Claims] A magnetic disk device that roughly positions a magnetic head with respect to a target data track using a head position detection means, comprising: dividing a magnetic disk into a plurality of data areas each consisting of a plurality of data tracks; A reference servo track is provided in a circumference in the data area, an off-track amount is stored in relation to the reference servo track for each data area, and when the magnetic head is moved, positioning is performed by the head position detection means. A magnetic disk device characterized in that the magnetic head is shifted by the memorized off-track amount after the off-track operation is performed.