JP2507303B2 - Magnetic head positioning method - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head positioning method for moving a magnetic head to a reference track position using a stepping motor.

[Technical background of the invention and its problems]

The positioning method of the magnetic head in the magnetic disk device is roughly classified into a closed loop positioning method using a voice coil motor and an open loop positioning method using a stepping motor.

The former enables high-accuracy positioning and high-speed access, but forms servo information on one side of the disk or part of the data zone and determines the position of the magnetic head based on this servo information. There is a drawback that the area for recording the original data is reduced. Moreover, in the servo surface servo system, the drive circuit becomes extremely complicated and the price increase cannot be avoided.

The latter method, on the other hand, is inferior in performance to the former method, but can realize a small and low-cost head moving mechanism, and is used in thin 5.25-inch and 3.5-inch fixed hard disk drives. There is.

By the way, in order to position the magnetic head using the stepping motor, recalibration for finding the reference track position is first required. Therefore, conventionally, an optical shield plate is attached to a movable shaft of a stepping motor that moves the head, and the reference position of the magnetic head is detected by shielding the light of an optical switch installed on the fixed side.

However, as the track density has been gradually improved in recent years, it has become very difficult to adjust the mounting position of the optical switch, and there is a problem that the manufacturing cost increases due to this position adjustment. Further, there is a problem that the existence of the photodetector becomes an obstacle in further miniaturizing the magnetic disk device.

[Object of the Invention]

The present invention has been made on the basis of such a problem, and an object of the present invention is to provide a magnetic disk device for positioning a magnetic head by using a stepping motor without providing a special detector. It is an object of the present invention to provide a magnetic head positioning method that enables accurate positioning of a magnetic head on a reference track, which can reduce the size and cost of a magnetic disk device.

[Structure of Invention]

According to the present invention, a magnetic head is driven by a stepping motor that can selectively take a plurality of kinds of excitation states, and a plurality of magnetic heads that the magnetic head can take when the stepping motor is in a specific excitation state on a data zone of a rotating magnetic disk. In the magnetic head positioning method for positioning the magnetic head at a reference track position set to any one of the above positions, a guard zone is provided on at least one of the outer circumference and the inner circumference of the data zone of the magnetic disk. A pattern composed of a magnetization reversal portion and an erase portion longer than the maximum magnetization reversal period of this magnetization reversal portion is repeatedly formed on a plurality of tracks constituting the guard zone information, and the stepping motor is driven to cause the magnetic head to While moving in the radial direction on the magnetic disk, the magnetic head Stops the stepping motor when it detects the pattern for a first predetermined number of times, and when the magnetic head detects the pattern for a second predetermined number of times greater than the first predetermined number of times in this stopped state, the stepping motor is stopped. It is characterized in that the magnetic head is positioned at the reference track position by driving again to bring it into the specific excited state.

〔The invention's effect〕

According to the present invention, special guard zone information is usually formed in a guard zone in which no information is recorded, and the magnetic head detects the guard zone information to position the data track on the reference track. Therefore, an optical position detector is not particularly required. Therefore, the size of the magnetic disk device can be reduced, and the manufacturing cost can be reduced because the mounting position of the position detector is not adjusted even if the track density is increased.

Example of Invention

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1A is a diagram showing a magnetic disk used in this embodiment. That is, in the magnetic disk 1 composed of, for example, several media, a guard zone 3 is formed on the outer periphery of the data zone 2 in addition to the data zone 2 for recording the original information. The guard zone information described later is formed in this guard zone 3. Note that the magnetic head is initially positioned 0
The track (reference track) is set to the outermost periphery of the data zone 2, that is, the track adjacent to the guard zone 3.

In the guard zone 3, as shown in FIG. 1B, guard zone information 12 is recorded on each of a plurality of tracks 11 (eight tracks in this example). This guard zone information 12 is a continuous recording part 13 recorded at a constant pitch.
And the erase (erase) section 14 which is sufficiently longer than the maximum magnetization reversal interval of the continuous recording section 13 are alternately repeated. Since these are continuously formed at a constant pitch in the circumferential direction, the phase between tracks is different. Such information is written and formed by the drive head rather than being written in clock cycles. The pitch of the continuous recording unit 13 is determined by the feed speed of the magnetic head 22 and the rotation speed of the magnetic disk 1. That is,
When the magnetic head 22 moves in the radial direction of the magnetic disk 1, it is necessary to arrange the magnetic heads 22 at such a pitch that at least several continuous recording portions 13 can be detected while passing one track.

FIG. 2 shows the structure of an apparatus for positioning the magnetic head at 0 track.

Reference numeral 21 in the figure is a control circuit (CPU) which is the center of the positioning function of the magnetic head. At the time of recalibration, the control circuit 21 selects the magnetic head 22 which is a dedicated head for reading the disk surface having the guard zone information, regardless of the selection of the magnetic head by the external interface. The reproduced signal from the magnetic head 22 is amplified by the amplifier 23, input to the slicer 24 and binarized, and then input to the guard zone detection circuit 25. The guard zone detection circuit 25 is composed of, for example, a retriggerable monostable multivibrator (hereinafter, simply referred to as “monomulti”), and the control circuit 21 uses the detection pulse of the erasing unit 14
Is to interrupt.

The control circuit 21 determines the position of the magnetic head 22 based on the inputted erase detection pulse, and the D / A converter 26,
The digital excitation information is output to 27. This excitation information is D / A converted by D / A converters 26 and 27, respectively. The drive circuits 28 and 29 supply an exciting current to the exciting coils 30 and 31 based on the signals from the D / A converters 28 and 29 to drive the movable portion 33 of the stepping motor 32.

Next, the recalibration operation will be described with reference to FIGS.

In the positioning of the open loop type magnetic head using the stepping motor 32, it is necessary to constantly record the position of the magnetic head. However, when the power is turned on, it is uncertain which track the magnetic head is located on. Therefore, it is necessary to search for 0 track immediately after power-on and position the magnetic head 22 with reference to this reference track. This recalibration work may be performed only once after the power is turned on.

The general operation of recalibration in this embodiment is shown in FIG. That is, after the power is turned on, when the spindle motor reaches normal rotation and the magnetic head floats above the disk surface, the magnetic head is moved toward the outer circumference of the magnetic disk (41), and the magnetic head is kept moving.
Performs a loose condition 1 guard zone information detection judgment (4
2). When the guard zone is detected under the loose condition 1, the magnetic head is stopped at that position (43), and then the guard zone information detection judgment is performed again under the severe condition 2 (4
Four). As a result, when the guard zone information is detected, the magnetic head is moved to the 0 track position (45).

In the loose condition 1, the guard zone information 12 is read while the magnetic head 22 moves. In this case, the magnetic head 22 travels obliquely with respect to each track 11 in the guard zone 3 as shown by the dotted arrow in FIG.
As indicated by Si in FIG. 4, it is an indefinite reproduction signal when traveling between tracks, and a reliable reproduction signal only when traveling on a track where the amplitude becomes large. In this reliable part, the burst part and the erasing part are alternately connected. This signal is sliced by the slicer 24 at a predetermined threshold value Th to become a binarized pulse signal shown in FIG. The guard zone detection circuit 25 detects the erasing section 14 by monomulti having a time constant slightly longer than the cycle of the burst section of the binarized pulse signal Sp, and the control circuit using this erase detection signal Se.
Interrupt 21. The control circuit 21 measures the erase period T or its cycle with an internal timer each time an interrupt is applied. Then, in a predetermined cycle, for example, 2
When the interrupt is applied continuously, it is determined that the magnetic head 22 is located on the guard zone 3 and the movement of the magnetic head 22 is stopped.

Under strict condition 2, the magnetic head 22 is stopped, and if the control circuit 21 is interrupted at a predetermined cycle, for example, 10 times, it is determined to be in the guard zone 3. If this is not the case, it means that the determination of Condition 1 is incorrect.
In this case, the magnetic head is moved again and the condition 1 is determined.

When the guard zone 3 is detected in this way, the magnetic head 22 is moved to the 0 track position by the following procedure.

That is, assuming that the stepping motor 32 is driven by 1-2 phase excitation, there are eight excitation states.
FIG. 5 shows these eight kinds of excitation states. The values of the exciting currents A and B flowing in the exciting coils 30 and 31 of the stepping motor 32 are
There are three types of + i, 0, and -i, and by combining these, eight types of excited states can be obtained. When the excitation state is changed by 1, the track moves by 1 track. Therefore, the stepping motor 32 is
The same excitation state is obtained every time 8 tracks are moved. In this example, the excitation state when the magnetic head 22 is positioned on the 0 track is set to the excitation 0 state. Since the guard zone information 12 is written in 8 tracks, the magnetic head 22 is moved to the inner circumference side of the magnetic disk 1 after the guard zone 3 is detected. Judge that the position is 0 track. The guard zone information 12 does not need to be recorded from the next track adjacent to the 0th track on the outer peripheral side. This is because it is only necessary to set the position where the excitation becomes 0 toward the inner circumference side of the innermost track of the guard zone 3 as the 0 track position.

In the present embodiment described above, the guard zone information 12 is written by the drive head without using the basic clock pre-recorded on the magnetic disk 1. Therefore, the phase of the erasing section 14 between the tracks of the guard zone 12 is changed. A gap occurs. Therefore, the reproduction signal between tracks is uncertain. However, the guard zone 3 can be reliably detected by performing the two-stage determination as in the present embodiment.
In addition, under the mild condition 1, it is sufficient if only a few erasing sections 14 can be detected, and therefore the detection time is not significantly delayed even by the two-step detection method.

The present invention is not limited to the above embodiment. For example, as shown in FIG. 6, guard zone information 12
When the data is written in the magnetic disk 1 in synchronism with the basic clock written in advance, there is no phase shift between the tracks, and it is not necessary to perform the two-step detection as described above.

In addition, as shown in FIG. 6, the guard zone information 12 is
A single magnetization reversal unit 51 and a single erasing unit 52 may be used.

Further, the present invention has exactly the same effect even if the guard zone is provided on the inner peripheral side of the data zone.

[Brief description of drawings]

FIG. 1 is a diagram showing a magnetic disk used in a magnetic disk device according to an embodiment of the present invention, FIG. 2 is a block diagram showing a partial configuration of the magnetic disk device, and FIG. 3 is an operation of the device. FIG. 4 is a flow chart for explaining FIG.
FIG. 6 is a diagram showing an exciting current of the stepping motor, and FIG. 6 is a diagram showing a part of a magnetic disk of a magnetic disk device according to another embodiment of the present invention. 1 ... Magnetic disk, 2 ... Data zone, 3 ... Guard zone, 11 ... Track, 12 ... Guard zone information,
13: Continuous recording section, 14, 52: Erase section, 22: Magnetic head, 32: Stepping motor, 51: Magnetization reversing section.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazunori Moritani 1 Komukai Toshiba Town, Komukai-ku, Kawasaki City (56) References JP-A-55-64665 (JP, A) JP-A-56 -93147 (JP, A) JP-A-56-22260 (JP, A) Actually developed 58-166300 (JP, U)

Claims (2)

(57) [Claims] 1. A magnetic head is driven by a stepping motor capable of selectively taking a plurality of kinds of exciting states, and the magnetic head can take a specific exciting state of the stepping motor on a data zone of a rotating magnetic disk. In a magnetic head positioning method for positioning the magnetic head at a reference track position set to any of a plurality of positions, a guard zone is provided on at least one of an outer circumference and an inner circumference of the data zone of the magnetic disk. A pattern composed of a magnetization reversal portion and an erase portion longer than the maximum magnetization reversal period of the magnetization reversal portion is repeatedly formed on a plurality of tracks forming a zone to form guard zone information, and the magnetic head is driven by driving the stepping motor. While moving in the radial direction on the magnetic disk, the magnetic Head stops the stepping motor when the pattern was first predetermined number of times detected, the second the magnetic head is often the pattern than the first predetermined number of times in this stopped state
When the predetermined number of times is detected, the stepping motor is driven again to bring the magnetic head into the specific excitation state, thereby positioning the magnetic head at the reference track position. 2. The magnetic head positioning method according to claim 1, wherein the magnetization reversal portion of the guard zone information is formed in a burst shape.