JPS63111000A - Positioning apparatus for head of magnetic disk device - Google Patents

Abstract

PURPOSE:To position a head precisely by memorizing the ratio of the quantities of conduction fed to a stepping motor after each position execution. CONSTITUTION:A stepping-motor drive circuit 8 turns a stepping motor 7 by a fixed quantity. The stepping motor 7 has four-phase excitation phase, and the stepping-motor drive circuit 8 changes the duty ratio of the quantities of conduction among each excitation phase of the stepping motor 7, and controls the quantity of drive by a microstep system. A microcomputer 12 each positions a head in succession in the inner circumferential direction and the outer circumferential direction, and stores the ratio of the quantities of conduction to the stepping motor after respective positioning. When positioning the head, the direction of seek of the head is discriminated, and the stepping motor 7 is driven by the ratio of the corresponding quantities of conduction.

Description

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

[Prior Art] Magnetic disks have a much higher track density than floppy disks, etc., and require high precision in head positioning. Therefore, during the positioning, servo control is performed in which the positioning is performed while reading servo information recorded on each track of the magnetic disk and detecting the position of the head.

Furthermore, a step motor is often used as the head actuator for positioning.

In this case, microstep driving is performed in which the ratio of excitation voltage to the two excitation phases of the step motor is changed to adjust the amount of rotation of the step motor based on the amount of off-track detected from the servo information. .

FIGS. 5(a) to 5(c) show an example of the above method. In this case, the excitation phase φ1. 4 of φ21rllT2
In a step motor having phases, excitation voltages Vl and v2 are simultaneously applied to excitation phases φ1 and φ2, as shown in FIG. 2(a). As shown in the same figure (b), this excitation voltage v1゜v2 is set so that the sum of the on-times Tl and T2 becomes a constant period T, and the ratio of the times T1 and T2, that is, the duty ratio. can be changed.

If this time TI, T2 is set to T+=T2, the same figure (
As shown in C), the magnetic pole of the rotor of the step motor comes to rest at the center of the excitation phases φ1 and φ2. Further, when setting TI>T2 or TI<72, the magnetic pole stops at the excitation phase φ1 or φ2 from the center depending on the duty ratio. In this way, the excitation φ! If the excitation state in which φ2 and φ2 are excited in a certain direction is A, then this step motor is 4
Since the rotor is in phase, the amount of rotation of the rotor is adjusted in the same way as above in the excitation state to D.

When positioning the head, the above-mentioned times TI and T2 are set based on the off-track amount detected from the servo information recorded on the track, and the step motor is driven to correct the position of the head and position it at a predetermined position. It uses servo control.

On the other hand, in magnetic disk devices, the biggest cause of off-track occurrence, which is the positional deviation of the head from the target track, is thermal damage caused by the expansion and contraction of the mechanical parts of the carriage that mounts the magnetic disk and head due to temperature changes inside the device. Off-track is known.

For this reason, immediately after the power of the magnetic disk device is turned on, the head is sequentially positioned on sampling tracks, which are a plurality of preset data tracks, by predetermined servo control. Then, when the step motor is positioned on each track, the ratio of the amount of current applied to the step motor is stored. Thereafter, when the head is positioned on a predetermined data track according to instructions from the host computer, the step motor is controlled according to the stored current ratio, and initial positioning is performed according to the temperature during operation. Thereafter, accurate positioning is performed by predetermined servo control based on servo information recorded on the data track.

By the way, conventionally, the operation of positioning the head with respect to the sampling track and determining the amount of energization to the step motor as described above involves sequentially seeking the head from the outer circumference side to the inner circumference side with respect to multiple sampling tracks. This was done either by searching from the inner circumference to the outer circumference, or by sequentially seeking from the inner circumference to the outer circumference.

On the other hand, the driving force of the step motor is generally transmitted via a rack gear and pinion gear or a steel belt to a carriage on which the head is mounted, thereby causing the head to move. In this case, this is due to the effects of backlash due to play and loosening of the gears and belts, and friction of the carriage mechanism.

Even if you move the head a certain distance by driving the step motor in a certain direction at a certain angle, and then drive it in the opposite direction at the same angle,
The head will not return to its original position. That is,
Here, considering the displacement of the head position with respect to the set duty ratio ↓2, as shown in Fig. 6, when the excitation phases φ1 and φ2 of the step motor are excited in a constant direction with a constant duty ratio, the step motor Assuming that the rotor stops at a fixed position and the head can be positioned on track j, the duty ratio d! is required to rotate the rotor clockwise and stop at that position. In order to rotate counterclockwise and stop at that position, the duty ratio must be set to d2. In other words, the duty ratio to be set varies depending on the direction in which the head is sent, as shown by R and R.

However, conventionally, the ratio of energization amounts (duty ratio) stored by the positioning operation to the sampling track as described above was determined by sending the head in one direction, so the actual ratio of energization amounts is When positioning the head based on this method, there is a problem in that the initial positioning of the head is not performed accurately if the moving direction of the head does not match the direction at the time of sampling. Therefore, the off-track that occurred at that time had to be corrected by servo control.

[Objective] An object of the present invention is to solve the above-mentioned problems and provide a head positioning device for a magnetic disk drive that can accurately position the head.

[Structure] Therefore, the present invention provides an operation for sequentially positioning the head from the outer circumferential side to the inner circumferential side of the sampling track.

Execute the sequential positioning operation from the inner circumference side to the outer circumference side,
After each positioning is performed, the ratio of the amount of current supplied to the step motor is stored, and when the head is positioned, the seek direction of the head is determined and the step motor is driven according to the ratio of the corresponding amount of current.

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 installed in a computer system (not shown) as a unit, and power is supplied from the main body. In FIG. Driven. 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 step motor 7 has four excitation phases as shown in FIG. 5(a), and the step motor drive circuit 8 operates as shown in FIG.
Each excitation phase φ1. The driving amount is controlled by a microstep method by changing the duty ratio of the amount of current flowing between φz, drt, and $2.

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, read 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.

The head positioning device of the magnetic disk device of this embodiment has the above configuration and operates as shown in FIG. 2. That is,
When this device is powered on.

The microcomputer 12 is a step motor drive circuit 8
is controlled to rotate the step motor 7 by a predetermined amount by a predetermined servo operation, and first, one of the heads 6a or 6b selected in the initial state is caused to seek to track 0, which is the reference position (process 20).

By the way, the magnetic disk 1 of this embodiment has tracks O to 5.
It has 99 data tracks, and these data tracks are managed by being divided into zones 1 to 6 of 100 tracks each. Furthermore, since the step motor 7 has four types of excitation states A to D as shown in FIG.
Corresponding to D, Tl1-Tl4°T21-T24. ...
..., four tracks T61 to T6a are set as sampling tracks.

Next, the step motor 7 is rotated by a predetermined step to move the heads 6a and 6b to the first sampling track T++.
Seek to. Although the explanation is omitted in the above process 20, at the time of positioning the head.

The information recording/reproducing circuit 9 reads the recorded information of the sampling track from the head 6a or 6b. The servo signal detection circuit 10 detects a servo signal among the signals obtained by reading the signal, and outputs a signal indicating the amount of off-track through predetermined processing.

The microcomputer 12 monitors the signal, controls the step motor drive circuit 8, and applies the excitation voltage v1. Adjust the duty ratio of v2. As a result, the heads 6a and 6b are correctly positioned on the sampling track (process 21).

Since the sampling track T++ is set to the excitation state A, the microcomputer 12 receives the excitation voltage v1. The duty ratio Dir+ of v2 is stored in the duty table formed in the internal memory (process 22).

Next, the process returns to the above process 21 (from N in process 23), and the same operation is performed on the primary sampling track T12, and the corresponding duty ratio Di+2 is stored. By repeating these operations, the duty ratio Di+ 〜Di+ is written in the duty table as shown in FIG.
4, Di 2 r ~01241 ・
. . , Dis+ to Die< are stored, respectively.

When the storage of the duty ratio Di6z corresponding to the final track 64 is completed (Y in process 23), the head 6a.

6b again to the previous sampling track Tg3, and positioning is performed in the same manner as above (24). The duty ratio DO63 at that time is stored (process 25), and the process returns to the above process 24 (N in process 26), and the heads 6a and 6b are further positioned on the previous sampling track, and the duty ratio at that time is stored. Repeat the action of memorizing.

Here, when the storage of the duty ratio D011 corresponding to the I&first sampling track Ttt is completed (Y in process 26), the heads 6a and 6b are positioned on track 0 (process 27).

Thereafter, the microcomputer 12 detects the off-track amount of the heads 6a and 6b that were positioned just before, performs servo control in the same manner as described above, and maintains the head position (process 28).

Here, if a control command is not received from a disk controller (not shown) (N in process 29), the above process 2
Return to step 8 and repeat the same operation at regular intervals.

Further, if any control command is received from the disk controller (Y in process 29), the command is identified. When the received control command is a seek command (Y in process 30), the microcomputer 12 drives the step motor 7 to cause the predetermined heads 6a, 6b to seek to a predetermined data track.

As shown in FIG. 3, the duty table formed in the internal memory of the microcomputer 12 includes the head 6
The seek directions of a and 6b, the excitation state fiA-D, and the duty ratios for each of zones 1 to 6 are stored. Therefore, the step motor 7 is driven with an excitation voltage according to the duty ratio corresponding to the state at this time to position the head (process 31).

Next, the microcomputer 12 detects the off-track amount at this time from the signal output from the servo signal detection circuit 10 in the same manner as described above (process 32).1 Next, the off-track amount is within a certain tolerance range. It is determined whether or not (processing 33).

Here, when the detected off-track amount exceeds a certain permissible value (N in process 33), the step motor 7 is controlled according to the off-track amount. This results in
The positions of heads 6a and 6b are corrected (processing 34)
. Thereafter, the process returns to step 32, and detection of the amount of off-track and correction of the positions of the heads 6a and 6b are repeated. At this time, in process 32, if the detected off-track amount falls within the above-mentioned allowable range (Y in process 33), the microcomputer 12 sends a seek completion signal to the disk controller (not shown) via the interface circuit 11. Output (process 35).

Thereafter, the process returns to step 28, and the head position is held until the next seek command is received.

Thereafter, the information recording/reproducing circuit 9 can record or reproduce information on the magnetic disk 1 according to commands from the disk controller. Further, when receiving another command such as a head selection command (N in process 30), a predetermined operation is executed.

Here, for example, as shown in FIG. 4(a), a head 6a.

6b from track O of zone 1 to track 2.6b. Let us consider the case of sequentially seeking to track 3 and then again to track 2. First, the step motor 7 is driven in the excitation state A with the duty ratio Dirt of the excitation voltage to drive the heads 6a, 6.
The same figure (b) shows the state where b is positioned on track 0.
As shown in (A), when seeking to track 2, heads 6a and 6b are sought inward,
Since this corresponds to the excitation state C, the step motor 7 is driven at the duty ratio [)iss, as shown in FIG. As a result, initial positioning is performed on the track 2 as shown in (b) of FIG.

Next, the positional deviation is corrected by predetermined servo control. Next, when seeking to track 3, it is driven with the duty ratio Dila in the same manner as above.

Predetermined servo control is performed.

Next, when returning to track 2, heads 6a and 6b
Since the step motor 7 is sought outward, the step motor 7 is driven at a duty ratio D013 as shown in FIG. As shown in Figure 6, if the head position is to be stopped at a fixed position, the duty ratio of the excitation current must be set according to the rotation direction of the motor, as shown in the figure or according to R. Since the step motor 7 is driven by the duty ratio D013 corresponding to the other direction of rotation, it is correctly positioned on the track 2 as shown in (b) of FIG. 4(b). In this way, the duty ratio corresponding to the seek direction of the heads 6a and 6b is selected, and the head is positioned with respect to each track.

As described above, in this embodiment, the heads 6a and 6b are made to seek each sampling track in the inner direction and the outer direction of the magnetic disk 1, and are sequentially positioned, and the excitation voltage to the step motor 7 after each positioning is determined. While remembering the duty ratio.

When positioning the heads 6a and 6b, the step motor 7 is driven according to a duty ratio corresponding to the seek direction of the heads. As a result, head 6
Shifts in head position due to play or loosening of gears and bells 1- for driving the heads 6a and 6b, and friction of movable parts are reduced, making it possible to accurately position the heads 6a and 6b.

In this embodiment, the magnetic disk 1 has tracks 0 to 5.
99, the number of zones is 6, and the excitation state of the step motor 7 is 4.
Although the case of seeds has been explained, it goes without saying that these numbers can be set arbitrarily.

[Effects] As described above, according to the present invention, the head is sequentially positioned on each sampling track in the inner circumferential direction and the outer circumferential direction, and after each positioning, the ratio of the amount of current applied to the step motor is memorized, and the head is positioned. In some cases, the seek direction of the head is determined and the step motor is driven by the corresponding current ratio, which reduces head misalignment due to play, looseness, or friction in the mechanism that drives the head. Accurate positioning becomes possible.

[Brief explanation of the drawing]

FIG. 1 is a block configuration diagram of a magnetic disk device according to an embodiment of the present invention, FIG. 2 is a flowchart showing head positioning operation, FIG. 3 is an explanatory diagram of a duty table, and FIGS. b) is an explanatory diagram of head positioning operation, Fig. 5(a) is an explanatory diagram of microstep drive, and Fig. 5(b) is an explanatory diagram of the head positioning operation.
) is an explanatory diagram of the excitation voltage, FIG. 6 (c) is an explanatory diagram showing the relationship between the duty ratio of the excitation voltage and the stop position of the rotor.
The figure is an explanatory diagram showing the relationship between the duty ratio of the excitation voltage and the head position. 1... Magnetic disk, 2... Disk support. 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 . Agent Patent Attorney Crest 1) Makoto) K Bello, NL Law IP Fig. 2 Fig. 3 Fig. 4 (a) (b) Deute, Rue - Fig. 5 (a) (b) (c) Deute I □ Figure 6 Dutyier □

Claims (1)

[Scope of Claims] A head positioning device for a magnetic disk device including a microstep drive means that adjusts a stop position by changing the ratio of energization amounts to two excitation phases of a step motor to be driven, wherein the head is set in advance. The ratio of the amount of current supplied to the step motor when each sampling track is sequentially positioned from the outer circumferential side to the inner circumferential side, and the above-mentioned amount of current supplied when each of the sampling tracks is sequentially positioned from the inner circumferential side to the outer circumferential side. and a control means for determining the seek direction of the head when positioning the head, reading out the stored ratio of energization amount corresponding to that direction, and controlling the microstep drive means. A head positioning device for a magnetic disk device, characterized in that: