JPS6350985A - Head positioning mechanism for magnetic disk device - Google Patents

Abstract

PURPOSE:To shorten a time for positioning a head to the reference position by moving the head at the interval of a track integer times of the exciting state of a step motor. CONSTITUTION:A servo information detection circuit 10 outputs the signals Va, Vb of a signal level corresponding to servo information. When a microcomputer 12 detects both the signals Va, Vb, it causes the heads 6a, 6b to seek eight tracks externally. Under this state, when only the Va is detected, it is judged that the head is situated in an outer guard band 16, the heads 6a, 6b are sought by four tracks internally. When the signals Va, Vb are detected again, the heads 6a, 6b are sought by three tracks externally. Thereby, the heads 6a, 6b are situated at the tracks of the reference positions. Thus, the positioning time of the head to the reference position can be shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a head positioning device for a magnetic disk device.

[Prior Art] When a step motor is used as a head actuator for a magnetic disk device, the step motor is driven by a two-phase excitation force type, and the ratio of the amount of current to the two magnetic excitation phases is adjusted to rotate. A microstep drive method that sets the amount arbitrarily is often adopted. In such a disk device, the head is first set at track 0, which is a reference position, and then driven from that position by a predetermined number of steps to position the head on a target track.

Therefore, when the power of the disk device is turned on, the microconverter that controls the step motor detects the position of the head, and if the head is not at the reference position,
The bed actuator is driven to position the head at a reference position. In this case, two methods are available: one is to determine the head position by detecting the position of the carriage on which the head is mounted and the rotation angle of the step motor using a photo sensor, and the other is to use a head on that track to read the servo information recorded on each track. A method of determining the head position from a read signal is known.

FIG. 7 shows an example in which the head position is determined by the latter method and the head is positioned at the reference position. In the figure, this magnetic disk has a data track area from track 0 to track k, which is the reference position of the head, and an outer guard band from track -1 to track -5 outside the data track area. In this example, the excitation state of the step motor that drives the head is 4.
There are two states A-D, and the head is in each excitation state A-D.
By sequentially energizing the step motor with , the track moves one track at a time. At this time, the position of the head and each excitation state A to D correspond as shown.

When the power is turned on to this magnetic disk device, the microcomputer first moves the step motor to track-1.
It is excited in the excitation state A corresponding to .

Assuming that the head is now located on data track j, this causes the head to seek to track i-2 in the example shown in the figure. Next, the microcomputer reads the servo information recorded on this track.

Two types of servo information are recorded on each data track, whereas only one of them is recorded on each track of the outer guard band. The microcomputer determines whether the head is currently on the data track or on the outer guard band based on the difference in the servo information read above.

Here, when the head is on the data track, the step motor is rotated four steps until the next excitation state A is reached, and the head is further sought to the outside by four tracks. Next, determination is made in the same manner as above, and if the head is still on the data track, seek is performed in the same manner as above, and such determination and seeking are repeated.

When the head reaches track-1 and the above determination determines that the head has reached the outer guard band, the excitation state of the step motor is switched from A to B.

As a result, the head is positioned at track 0, which is the reference position.

In this way, in the conventional positioning of the head to the reference position, the servo information recorded on the track at that time is detected for each specific excitation state.

However, in order to determine such a head position, a reading time is required for the magnetic disk to rotate each time the servo information is detected and for the servo information to pass through the head. Therefore, there is a problem in that it takes time to position the head at the reference position.

[Objective] An object of the present invention is to provide a head positioning device for a magnetic disk device that solves the above problems and shortens the time required to position the head to a reference position.

[Structure] Therefore, when the head is positioned at the reference position, the present invention moves the head at a moving interval that makes the number of tracks equal to an integral multiple of the number of excitation states of the step motor that drives the head. The outer guard band is formed with a number of tracks corresponding to the above-mentioned number of tracks, which is the movement interval of the outer guard band.

Examples of the present invention will be described in detail below.

FIG. 1 is a block diagram of a head positioning device for a magnetic disk device according to an embodiment of the present invention. This device is unitized and installed in a computer system (not shown), and power is supplied from the main body. In the figure, a magnetic disk 1 is fixed to a disk support 2 and driven by a spindle motor 3. The spindle motor drive circuit 4 rotates the spindle motor 3 at a constant speed. The carriage 5 is mounted with read/write heads (hereinafter simply referred to as heads) 6a and 6b that contact each data recording surface of the magnetic disk 1, and is driven by a step motor 7. The step motor drive circuit 8 rotates the step motor 7 by a predetermined amount.

The information recording/reproducing circuit 9 sends a write signal to the heads 6a, 6b and also extracts the read signal, and the servo signal detection circuit 10 detects a servo signal from the extracted read signal. The interface circuit 11 is connected to a host computer (not shown) via a disk controller (not shown), and sends and receives control signals, status signals, successive data, or write data to and from the disk controller. The microcomputer 12 receives predetermined signals from each of the circuits described above, and
It controls each of the above circuits.

As shown in FIG. 2, the data surface of the magnetic disk 1 includes an inner guard band 13 formed on the innermost side and a shipping area 14 to which the head is normally moved before power is turned off.
and a data track area 15 for recording data.
It has an outer guard band area 16 outside the data area. The servo control method for head positioning of this magnetic disk device employs an index burst servo method. Mechanical index position IX
In front of is a position information area 17 for servo control.
is provided.

Details of this position information area 17 are shown in FIG. In the figure, each number of tracks TR-5 to TRn is a track number assigned for convenience, with track TRO, which is the reference position of the head, being 0. The position information area 17 is located in the gap between the index areas between the data areas DT. Data track T of data track area 15
Specific magnetization patterns Sa and sb (hereinafter simply referred to as servo information) are recorded as servo information in the position information areas 17 of RO to TRk 1 and tracks TRk++1 to TRk 2 of the shipping area 14. Also, tracks TR-1 to TR-T in the outer guard band area 16
In the area 17 of R-5, only servo information Sa is recorded. On the other hand, TRk 2 of Inner Guard Band 13
The area 17 from +1 to TRn contains servo information Sa.
, Sb are not recorded.

The step motor 7 is a permanent magnet type 2 as shown in FIG.
It is a phase step motor. The step motor drive circuit 8 drives the step motor 7 in a bipolar manner using a two-phase excitation drive force type. When the respective excitation states are indicated by A-D, each magnetic pole of the rotor comes to rest at each position shown in each state. At this time, for example, in the excitation state A,
Microstep driving is performed in which the amount of rotation of the rotor is controlled by adjusting the ratio of the amount of current applied to the excitation phases φ1 and φ2.

The head positioning device of the magnetic disk device of this embodiment has the above-described configuration and operates as shown in FIG. 5. That is,
When the power of this device is turned on, the microcomputer 12 unlocks the locking mechanism (not shown) that locks the carriage 5 (process 21).

By the way, in this embodiment, when the heads 6a and 6b are caused to seek track TR-1, the excitation state of the step motor 7 is set to A, and the excitation state in each track TRO to TRn is set to A. The result is as shown in FIG.

Assuming that the heads 6a and 6b are now located on the track TRi, the microcomputer 12 controls the step motor drive circuit 8 to excite the step motor 7 in the excitation state A (process 22). As a result, the head 6a
, 6b move to track TRi-2 in this example.

Next, the spindle motor drive circuit 4 is controlled.

The spindle motor 3 is started (process 23). The microcomputer 12 monitors the rotation speed of the spindle motor 3 based on a detection signal from a speed sensor (not shown) attached to the spindle motor 3 (processing 24).

The information recording/reproducing circuit 9 selects the head 6 selected at this time.
The recorded information of the track on which the head is located is read from a or 6b. The servo information detection circuit 10 detects the servo burst signals corresponding to the servo information Sa and Sb from the read signals obtained by the reading, and generates level signals Va and V indicating the signal levels of both of them.
b.

When the microcomputer 12 detects that the spindle motor 3 has reached a predetermined speed (■ in process 24),
Input the above level signals Va and Vb (processing 25)
.

Here, when both the signals Va and vb are detected (N in process 26), the heads 6a and 6b are located in the shipping area 14 or the data track area 15, so in this embodiment, the heads 6a and 6b are detected. 8 tracks outward (processing 27). Thereafter, the process returns to step 26, and the determination of the signals Va and Vb and the head seek are repeated.

Assuming that the above operation causes the heads 6a and 6b to seek to the track TR-5 of the outer guard band 16 on which the servo information sb is not recorded, as shown by the solid line in FIG. (Y in process 26). At this time, the heads 6a and 6b are made to seek 4 tracks inward (
Processing 28).

Next, in the same way as above, level signals Va and Vb corresponding to the servo information Sa and Sb are input, and their levels are detected (process 29). At this time, the heads 6a, 6
b is on track TR-1, only the signal Va is detected (Y in process 30), and the process returns to process 28. As a result, the heads 6a and 6b seek inward to the track TR3. Here, the level signals Va and Vb are input again (process 29). At this time, since both level signals Va and vb are detected (processing 3
0N), the heads 6a and 6b seek three tracks outward (processing 31).

As a result, the heads 6a and 6b are located at the reference position, which is the track TRO, so that the microcomputer 1
Step 2 controls the step motor 7 by predetermined servo control based on the level signals Va and Vb to accurately position the heads 6a and 6b on the track TRO (process 32). Next, the heads 6a, 6 are connected to a disk controller (not shown) via an interface circuit 11.
A status signal indicating that b is on track 0 is output (process 33).

On the other hand, in the present embodiment, in the process 27, the seek is performed in units of 8 tracks, so in the case where only the level signal Va is detected in the process 26, it is assumed that the level signal Va is detected in the process 26.
6b may be located on track TR-1 as shown by the broken line in FIG. At this time, as shown by the broken line in the figure, 4 tracks are sought inward (process 28), and then both the level signals Va and Vb are detected (N of process 30).
), after which 3 tracks are sought outward (process 31)
, becomes positioned on track TRO.

As described above, in this embodiment, when the step motor 7 that drives the heads 6a and 6b has four excitation states A to D, when the power of the apparatus is turned on, the head 6
When positioning the heads 6a and 6b at the reference position of the track TRO, the heads 6a and 6b are made to seek eight tracks at a time, which is twice the number of excitation states, while the outer guard band has tracks TR-1 to TR. -9
It forms nine tracks.

As a result, the number of times the head position is determined by reading the servo information Sa and Sb is reduced compared to the conventional method of seeking four tracks at a time.
The time required to position 6b on track TRO is reduced.

In this embodiment, the seek is performed in steps of 8 tracks in step 27, but the seek number Ns can be freely set as shown in the following equation, where n is an arbitrary integer.

N5=4·n Further, the number NG of tracks of the outer guard band to be formed at this time is as shown in the following equation.

Na=Ns-4 Furthermore, the present invention can be applied in the same manner as described above even when the step motor 7 has eight types of excitation states or other cases.

[Effect] As described above, according to the present invention, when the head is positioned at the reference position, the head is moved at a track interval that is an integral multiple of the number of excitation states of the step motor, while the outer guard band of the magnetic disk is Since the number of tracks corresponding to the track interval is formed, the number of times the head position is determined is reduced, and the time required to position the head to the reference position is shortened.

[Brief explanation of the drawing]

FIG. 1 is a block configuration diagram of a head positioning device of a magnetic disk drive according to an embodiment of the present invention, FIG. 2 is a configuration diagram of a data surface of a magnetic disk, FIG. 3 is an explanatory diagram of a position information area, and FIG. FIG. 5 is a flowchart showing the operation of the head positioning device, FIG. 6 is an explanatory diagram of the head position movement in the operation, and FIG. 7 is an illustration of the head position movement in the conventional head positioning device. It is an explanatory diagram. DESCRIPTION OF SYMBOLS 1... Magnetic disk, 2... Disk support body, 3...
... Spindle motor, 4... Spindle motor drive circuit, 5... Carriage, 6a, 6b... Read/write head, 7... Step motor, 8...
step motor drive circuit, 9... information recording and reproducing circuit;
10... Servo signal detection circuit, 11... Interface circuit, 12... Microcomputer, 13...
・Inner guard band, 14...Shipping area, 1
5... Data track area, 16... Outer guard band area, 17... Position information area, DT... Data area, Sa, Sb... Servo information. Figure 3 IX Figure 4

Claims (1)

[Claims] A step motor that moves the head onto each track of the magnetic disk, and 2 of the number of excitation states of the step motor.
A magnetic disk comprising an outer guard band positioning means for moving the head outward at a track interval corresponding to an integral multiple of the above, and an outer guard band area having a number of tracks corresponding to the track interval outside the data track area. a determining means for determining whether the head is located in the data track area or the outer guard band area based on a signal extracted from the head; and upon determining that the head is located in the outer guard band area; reference positioning means for returning the head inward at track intervals corresponding to the number of excitation states and moving the head outward a predetermined number of tracks when the head returns to the data track area; A head positioning device for a magnetic disk drive, characterized in that the number of times the determination is made is reduced to shorten the time required for positioning the head to the reference position.