JP2973247B2 - Head control method for magnetic disk drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a head control system for a magnetic disk drive employing a sector servo system, and more particularly to a multi-zone system having a variable clock frequency.
The present invention relates to a head control method for a magnetic disk drive using a method (hereinafter, referred to as a "multi-zone method") .

[0002]

2. Description of the Related Art In recent years, many magnetic disk devices adopt a multi-zone system in order to improve storage capacity. In a conventional multi-zone type magnetic disk drive, an encoder is used.
Alternatively, the head is controlled by adopting a servo surface servo system.

In a system using an encoder, the number of pulses generated by the encoder is counted using an internal encoder such as a light interference type, and the position and speed of the head are controlled. Things.

In the servo surface servo method, the entire surface of a magnetic disk is used as a dedicated surface for servo information, and the servo information is obtained by reading the servo surface by a head. The head position and speed are controlled using the servo information.

[0005]

However, the above-mentioned conventional head control system of a magnetic disk drive using the multi-zone system has the following problems when an encoder is used, for example.

(1) To increase the resolution of the encoder, it is necessary to reduce the pitch of the scale of the encoder.
In this case, the cost of the scale increases.

(2) When the head is moved by a rotary system, it is necessary to move the scale away from the center of rotation of the rotary arm in order to increase the resolution of the encoder. In such a case, the size of the drive of the magnetic disk drive increases, and the inertia increases, so that the seek speed cannot be increased.

Further, when the servo surface servo system is employed, there are the following problems.

(3) Since the servo surface and the data surface are different and the track information of the servo is taken in from the servo surface, the servo track information and the on-track of the data surface are changed due to a temperature change or the like. This is disadvantageous when applied to a magnetic disk storage device that easily shifts from information and further increases the density.

(4) Since the entire surface of the disk is used as a servo surface, especially in the case of a magnetic disk storage device having a small number of disks, the storage capacity is reduced and it is difficult to increase the capacity.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and is intended to provide a magnetic disk drive having high capacity efficiency and high density without using an encoder and without providing a servo surface. It is an object to provide a head control method.

[0012]

According to the present invention, there is provided a magnetic disk in which servo information is stored in a part of each sector in a data track on a first surface and a second surface of a magnetic disk. In a head control method for a magnetic disk drive which forms and determines the position of a head by reading servo information, a magnetic disk has a first surface and a second surface which are divided into a plurality of zones having different clock frequencies. The magnetic disk drive has a first area which is divided and has the same zone on the first surface and the second surface, and a second area which has a different zone. A plurality of reference clock generating means corresponding to each zone, for taking in a servo signal in a first area of a first surface;
To detect that the head has reached the second area.
And in the first step, when the first head reaches the second area, the head for capturing servo information is replaced with the second head for capturing servo information on the second surface. And a second step of switching to reference clock generating means having a clock frequency of a zone corresponding to the second area. In the second step, the second head is moved to the second area in the second area. The method is characterized in that a servo signal of the second surface is fetched.

Further, the plurality of clock generating means use at least two or more variable frequency oscillators.

[0014]

According to the present invention, the head control system of the magnetic disk drive is constituted as described above, and the first head which takes in the servo signal of the first surface of the magnetic disk reaches the second area. Then, the head is switched, and the second head catches a servo signal on the second surface having a clock frequency different from that of the first surface. Multi-zoning is possible.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a magnetic disk drive to which a head control method according to the present invention is applied. In the figure, 10 is a magnetic disk, 11 is a head, 12 is a head 11
An amplifier for amplifying the signal read from the CPU, 13 is a CPU 2
A decoder, which is a digital signal oscillator capable of switching an output signal in response to a head designation from 0, a reference clock switch 14 for switching a clock oscillator 15, a reference clock oscillator 15, and 20 for the entire magnetic disk drive. It is a CPU that controls.

The head 11 is provided on the upper surface 10 of the magnetic disk 10.
a and the lower head 10a on the lower surface 10b.
1b. The reference clock oscillator 15 is composed of n reference clock oscillators 15-1 to 15-n corresponding to the number n of zones of the magnetic disk 10.

FIG. 2 is a view for explaining the structure of the magnetic disk 10 according to the present invention. FIG.
(B) is a sectional view. As shown in the figure, in this embodiment, the magnetic disk 10 has four zones I to IV.
It is divided into two zones. Further, as shown in FIG. 3B, the area of the magnetic disk is composed of the normal areas I to IV in which the upper surface 10a and the lower surface 10b of the disk have the same frequency reference clock, and the reference clock of the different frequency in the upper surface 10a and the lower surface 10b. Overlap area I / II
~ III / IV. Further, in the magnetic disk of this embodiment, as shown in FIG.
Code No. 0, zone I on the lower surface is code No. 1, etc.
A number is attached. Servo sectors (not shown) of the magnetic disk 10 are located at the same position on the upper surface and the lower surface in the same zone.

Next, the operation of positioning the head of this embodiment will be described. FIG. 3 is a flowchart for explaining the head positioning operation.

First, the code number (current code) of the magnetic disk currently read by the head 11 is compared with the target code number (target code) (step ST301). When the current code and the target code are equal, the head 11 has already set the target zone on the target surface.
Since it has reached the normal position, a normal seek is performed (step ST305), and the process ends.

In step ST301 (-), that is, when the head 11 moves from the inside of the magnetic disk 10 to the outside, it is checked whether (current code-target code) is -1 (step ST302). Step ST3
03, (+), that is, the head 11
When moving from the outside of 0 to the inside, it is checked whether (current code-target code) is +1 (step ST30).
3). When -1 in step ST302 or +1 in step ST303, since the head 11 has reached the target zone on a surface different from the target surface, the CPU 20 instructs the decoder 13 to switch the head. Switching to the head on the opposite side (step ST30)
5) A normal seek is performed (step ST305).

The case where the head 11 moves from the inside to the outside of the magnetic disk 10 and switches from zone M to zone M + 1 will be described below. If it is not −1 in step ST302, the next currently operating head
That is, the head performing reading is the upper head 11a.
Is determined (step ST306). If the operation head is not the upper head 11a, the operation head is switched to the upper head 11a (step ST30).
7) Move the head 11 outward (step ST30)
8).

Thereafter, it is confirmed that the upper surface head 11a has reached the overlap area (step ST31).
2) The CPU 20 starts the timer (step ST)
313). Then, it instructs the decoder 13 to switch the head, and furthermore, switches the reference clock switch 14
An instruction is given to select a reference clock oscillator corresponding to input M + 1 (step ST314).

When the servo data of the zone M + 1 is confirmed by the lower surface head 11b, the process returns to step ST301.
If the servo data cannot be confirmed, it is determined whether or not the timer is within the set time (step ST31).
6) If within the set time, steps ST315 and ST316
repeat. CP if the timer set time has elapsed
U20 instructs the decoder 13 to switch to the original head, that is, the upper head 11a, and further instructs the reference clock changeover switch 14 to select the reference clock oscillator corresponding to the zone M ( Step ST
317). When step ST317 ends, step S317 is completed.
Returning to T312, the process is repeated.

In the case where the head 11 moves from the outside to the inside of the magnetic disk 10, the above-described step ST3 is also performed.
The same processing as in steps 06 to 317 is performed (step ST30).
9-311, 322-327).

Next, the head 11 is moved from the code No. 1 on the lower surface 10b of the magnetic disk to the upper surface 10a of the magnetic disk.
The case of moving to code No. 6 of FIG.

(1) First, in step ST301 (current code-target code), that is, 1-6 = -5 is obtained, and the process proceeds to step ST302. In addition, since it is −5 ≠ −1, the process proceeds to step ST306.

(2) Subsequently, since the currently operating head is the lower head 11b, the head is switched in step ST307, and the upper head 11a moves over the normal area I of the code No. 1 on the upper surface 10a of the magnetic disk. Move outward.

(3) Reaching the overlap area I / II,
When a servo sector is detected, the CPU 20 starts a timer. The set time of the timer is the same as the sampling period in zone I. Here, the sampling period is the time during which the head 11 passes between sectors in a certain zone. Then, the operation is switched to the lower surface head 11b, and the reference clock oscillator 1
5 from the reference clock oscillator 15-1 for zone I.
To be the reference clock oscillator 15-2 for the second II.

(4) Next, in step ST315, the lower surface head 11b is moved to zone II, that is, the servo of code No. 4.
Check the data. If it is not confirmed, the search is performed within the timer set time, that is, until the next sector in zone 1 comes.
The confirmation of the data is repeated.

(5) When the set time of the timer has elapsed,
Switching to the upper head 11a, the reference clock oscillator 15 is returned to the reference clock oscillator 15-1 for zone I, and the process returns to (3).

(6) If the servo data is confirmed in step ST315, the process returns to step ST301.
Here, since the current code is 4, (current code-target code) is 4-6 = -2. Accordingly, the process proceeds to steps ST302, 306, and 307, and the upper surface head 11a moves the normal area I of code No. 3 of the magnetic disk 10.
Move outward on top.

(7) Further, in steps ST312 to 317, the servo data of the zone III on the lower surface 10b of the magnetic disk is confirmed on the overlap area II / III.

(8) In step ST301, this time (current code-target code) is 7-6 = 1, so the process proceeds to step ST303 and step ST304, and when the head is switched to the top head 11a, Reach on the No.6.

Next, the processing in steps ST308 to ST317 will be described in detail. 4 to 6 are diagrams for explaining switching between the head and the reference clock.

FIG. 4 is a diagram showing a case where servo data in the overlap area is immediately confirmed. In FIG. 1, the head 11 is rotated for ease of explanation, but the magnetic disk 10 is actually rotating.

The head 11a on the normal area N moves on the magnetic disk upper surface 10a until it reaches the overlap area N / N + 1 (step ST308).

The upper surface head 11a reaches the overlap area N / N + 1, and the upper head 11a receives the overlap area N / N + 1.
When the data is confirmed (step ST312), the CPU
20 starts the timer after passing through the servo sector 412.
Then, the head is switched to the lower head 11b (steps ST313 and ST314).

When the lower head 11b confirms the servo data in the servo sector 422 of the zone N + 1 immediately after switching the head, the process returns to step ST301.

FIG. 5 is a diagram showing a case where the servo data is confirmed within the timer set time. Step ST308
The operation in steps 314 to 314 is the same as that described above, and a description thereof will be omitted.

If the lower head 11b cannot confirm the servo data of the zone N + 1, it checks whether or not the elapsed time t since the start of the timer is within the timer set time T (step ST316). ), If t <T, the servo data of zone N + 1 is checked again.

The processing within the range of t <T is repeated, and when the servo data in the servo sector 522 of the zone N + 1 is confirmed, the process returns to step ST301.

FIG. 6 is a diagram showing a case where servo data cannot be confirmed within the timer set time. Step ST3
The operations 08 to 316 are the same as those described above, and the description thereof is omitted.

If the servo data of the zone N + 1 cannot be confirmed within the timer set time T, that is, the servo sector passed when the upper surface head 11a starts the timer on the magnetic disk upper surface 10a. Before the time to reach the servo sector 612 next to 611, the head is switched to the upper surface head 11a (step ST317), and the magnetic disk upper surface 10a is switched.
The servo data in the servo sector 612 a is confirmed (step ST312), and the timer is started again (step ST313).

The lower head 11b is switched again (step ST314), and the elapsed time t from when the timer is started is t.
Is within the timer set time T (step ST
306), the servo data of the zone N + 1 is confirmed within the range of t <T (steps ST315 to ST316).

When the servo data in the servo sector 621 of the zone N + 1 is confirmed, the flow returns to step ST301.

As described above, the timer set time T is the sampling period in the zone before changing (zone N in the specific example), that is, the head passes between servo sectors. Time. Since the sampling period is constant in the same zone, the CPU 20 can set the time in advance.

The width L of the overlap area is given by the following formula: ts represents the sampling period in a certain zone, n represents the number of times of sampling, and Vh represents the maximum moving speed of the head.
> Vh * n * ts. Note that the number of times of sampling is as shown in FIG.
It depends on how many times the 17 loops are repeated. In this embodiment, n = 2 to 10 is appropriate.

Next, reference clock switching processing in step ST314 will be described. In the sector servo system, the pattern of the servo sector includes an erasing section, a synchronizing section, and a position information section. The erasing section is for detecting a servo sector, and is DC-erased. Synchronization section is bar
A strike pattern is used for setting a synchronization signal for detecting position information and setting an AGC (Auto Gain Control) level. The position information section is composed of coarse position information and precise position information so that the position can be recognized even if the head is moved by a plurality of tracks in one sector. Of these, the coarse position information is synchronized with the erasing section and takes timing.

In this embodiment, the CPU 20 generates a sector pulse in synchronization with the erasing section, and further measures the sampling period of the sector pulse, that is, the time interval between the sector pulses. Now, assume that coarse position information when a servo sector is detected is l (m + 1) and coarse position information when a previous servo sector is detected is l (m). Assuming that the time required until (m + 1) is t, the moving speed V of the head is obtained as V = (l (m + 1) -l (m)) / t.

Here, as shown in FIG.
From zone P + 1 to zone P + 1. As shown in the figure, the sampling period in zone P is T (P),
The sampling period at P + 1 is T (P + 1). Head moving speed V when coarse position information is l (q)
(q) is V (q) = (l (q) -l (q-1)) / T (P). On the other hand, coarse position information of the servo sector detected after the head moves to zone P + 1 is l (q + 1), l (q + 1).
Assuming that the time required from (q) to l (q + 1) is T ′, the moving speed V (q + 1) of the head at this time is V (q + 1) = (l (q + 1) − l (q)) / T ', and a stable movement of the head can be obtained.

Next, another embodiment of the present invention will be described. FIG. 8 is a block diagram showing the configuration of another magnetic disk drive to which another head control method according to the present invention is applied. In the figure, the portions denoted by the same reference numerals as those in FIG.
The description is omitted because it is the same as the magnetic disk device of FIG. In this magnetic disk drive, the reference clock oscillator 15 is composed of a synthesizer A15-a and a synthesizer B15.
−b, and the clock frequency is variable. FIGS. 9 and 10 are flowcharts for explaining the head positioning operation of another embodiment according to the present invention.

First, (current code-target code) is calculated, branching is performed based on the result, and switching of the head 11 in a predetermined case is performed in the same manner as in the first embodiment. Therefore, the description is omitted.

If (current code-target code) is (-), it is checked whether or not the zone (X zone) where the head 11 is located is an odd number (step ST9).
01). If the X zone is an odd number, the CPU 20 sends the synthesizer A1 to the reference clock changeover switch 14.
5-a is turned on (step ST902),
A reference clock frequency corresponding to zone (X + 1) is set for synthesizer B15-b (step ST).
903). On the other hand, if the X zone is even,
CPU 20 instructs to turn on synthesizer B15-b (step ST904), and synthesizer A15-a.
, A reference clock frequency corresponding to the (X + 1) zone is set (step ST905). Then, the clock frequencies of synthesizer A15-a and synthesizer B15-b are held (step ST906).

The same processing is performed when (current code-target code) is (+) (step S).
T911-916), and in this case, synthesizer A15
-A or synthesizer B15-b, (X-1)
The reference clock frequency corresponding to the zone is set (steps ST913 and 915).

Hereinafter, the same processing as the processing in steps ST312 to 317 in the flowchart of the first embodiment is performed, but in step ST314, the CPU 20 controls the reference clock changeover switch 14 to determine which synthesizer is currently turned on. It will instruct the user to turn off and turn on the other synthesizer that is not currently on.

[0056]

As described above, according to the present invention, the following excellent effects can be obtained.

An overlap area is provided on the magnetic disk, and the head is switched after the first head, which is taking in the servo signal on the first surface, reaches the overlap area. Since the second head on the second surface takes in a servo signal in a zone different from that of the first surface in the overlap area, the magnetic field cannot be obtained by the sector servo method. The disk can be multi-zoned , and the storage capacity can be increased, and the density of the magnetic disk can be increased.

Since the head is controlled without using the encoder, the size of the drive of the magnetic disk drive can be reduced, and the inertia of the arm can be reduced. Higher speed and lower power consumption of the magnetic disk drive are possible.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a magnetic disk drive to which a head control method according to the present invention is applied.

FIG. 2 is a diagram for explaining the structure of a magnetic disk according to the present invention.

FIG. 3 is a flowchart illustrating a head positioning operation according to the embodiment of the present invention.

FIG. 4 is a diagram for explaining switching of a head and a reference clock.

FIG. 5 is a diagram for explaining switching between a head and a reference clock.

FIG. 6 is a diagram for explaining switching of a head and a reference clock.

FIG. 7 is a diagram showing a case where the head moves from zone P to zone P + 1.

FIG. 8 is a block diagram showing a configuration of another magnetic disk drive to which the head control method according to the present invention is applied.

FIG. 9 is a flowchart illustrating a head positioning operation according to another embodiment of the present invention.

FIG. 10 is a flowchart illustrating a head positioning operation according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Magnetic disk 11 Head 12 Amplifier 13 Decoder 14 Reference clock switch 15 Reference clock oscillator 20 CPU

Continuation of the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) G11B 20/10 351 G11B 20/14 351 G11B 21/10

Claims (2)

(57) [Claims] A servo information is formed in a part of each sector in a data track on a first surface and a second surface of a magnetic disk, and the servo information is read out to form a head. In a head control method for a magnetic disk device for determining a position, the magnetic disk is divided into a plurality of zones having a first surface and a second surface having different clock frequencies, and the first surface and the second surface are divided. The magnetic disk drive has a first area that is the same zone and a second area that is a different zone, and the magnetic disk device has a plurality of reference clock generating means corresponding to the plurality of zones. A first step of detecting that the first head, which is taking in a servo signal for the first area of the first surface, has reached the second area, In the first step, the first When the head reaches the second area, the head for taking in the servo information is switched to the second head for taking in the servo information on the second surface, and the head corresponding to the second area is switched. And a second step of switching to the reference clock generating means having a clock frequency of -2, wherein in the second step, the second head is turned on the second surface in the second area. A head control method for a magnetic disk drive, wherein a head signal is fetched. 2. The head control method for a magnetic disk drive according to claim 1, wherein said plurality of reference clock generating means use at least two or more variable frequency oscillators.