JPH02121167A - Servo information setting system for magnetic disk - Google Patents

Abstract

PURPOSE:To shorten the writing time of the servo information by dividing a track into plural equal sectors, securing the phase difference between the angle positions of those sectors of each disk, and setting the sector servo information at the front head of each sector. CONSTITUTION:Each track is divided into equal (s) pieces of sectors. A phase difference theta/2N which is 1/2N of the angle theta that is subtended by one sector that is equally divided, where 2N is the number of data surfaces of the disk, is set for angle position of each sector on the upper and rear surfaces of each disk. Then the sector servo information M is set at the front head of each sector. When the information M is written, the shift of a head group is stopped and the switch signals are produced for each phase difference theta/2N via the angle signal produced by an angle generator. The heads are switched in the timing of the switch signal and connected to a servo writer. Thus the servo information are successively written into each sector. Therefore the writing tasks are through with one track on both sides of each disk with one rotation of a spindle. Thus the writing time of the servo information is shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for setting servo information on a magnetic disk, and more specifically to an angular position for setting servo information in a data-sector servo method.

[Prior Art] In a hard magnetic disk used as a recording medium of an information processing device, a large number of concentric tracks T are provided on the front and back surfaces of the magnetic disk 1, as shown in FIG. , each track T is equally divided into a plurality of S sectors 81-8s in the circumferential direction.In FIG. Data is written or read by moving along the center line C of T.

In a magnetic disk device, in order to increase the recording capacity, a plurality of N disks I-1,
12 to iN are assembled into a disk pack 1', and each disk is rotated simultaneously by a spindle 3. Here, 3
Reference character a designates a spindle motor, and heads 21, 22, .

Now, the width of the track T and the interval between each track are minute, and it is necessary to accurately position the head 2 with respect to the center line C, and servo information is used for this purpose. Of the disks in the disk pack 1', for example, the lowest IN is used exclusively for servo information, and servo information M is recorded at a position corresponding to each track T. This is called the servo surface servo method. As shown in FIG. 4(b), the servo information M is composed of pulse trains MQ and Ml alternately recorded on both sides of the center line C, and both pulse trains are read out by the head 2.
When the two levels are equal, the head aligns with the center line C, so the head 2 is moved by the carriage mechanism 2a and controlled so that they become equal. The servo information M is used not only to control the head position but also to generate clock pulses for data demodulation. In addition to this, it is also used in AGC, which automatically adjusts the gain of an amplifier.

In the servo surface servo method mentioned above, a dedicated disk is used, but with recent small disks,
The trend is to abolish this system and use a data surface servo force type in which each disk is made into a data disk and servo information is set in the data track of each disk.

FIG. 5 explains the sector servo method in the data surface servo method, and shows each data disk I-! ~IN, the sectors 5l-8s on both the front and back sides have the same phase in each data section, and servo information M and subsequent sector information are recorded by the servo writer at the beginning of these sectors.

[Problem to be solved] In the conventional sector servo method described above, the servo information +
In the sector information and data section following 1dM, the position control of the heald is not performed, and when the servo information is short, the stability of the clock pulse for data demodulation decreases. Also, when comparing the writing time of servo information by a servo writer, the servo method only writes to one disk, while the sector servo method described above writes to both sides of all disks, so this writing takes several disks. It takes twice as long as N.

On the other hand, in recent small disks, thin-film heads are used to accommodate high density, and positioning must be performed with higher precision than ever before. However, the servo surface servo method and the conventional data surface sector servo method each have advantages and disadvantages. In response to this, we proposed a system that uses both the servo system and the data surface sector servo system as a high-precision position control system ("Sector servo system combined with servo system"), Proceedings of the National Conference of the Electronics Association Society, 1981. , p, l-187), but
Both the configuration and control are complicated, making it difficult to put it into practical use.

This invention was made in view of the above, and compared to the conventional data surface sector servo system, the writing time of servo information can be shortened, the head position control time can be operated longer, and the clock for data demodulation can be operated for a longer time. The purpose of this invention is to provide a sector servo information setting method that can further stabilize pulses.

[Means for Solving the Problems] The present invention is a servo information setting method in a data surface sector servo method for a plurality of N disks constituting a disk pack, in which the tracks of each disk are
The angle made by the sector is 0 (= 380°) with respect to the angular position of each sector on each disk.
/ s ), the phase difference θ/ is 1/2N the number of data planes.
2N is provided, and sector servo information is set at the beginning of each sector.

In the above-mentioned aging of sector servo information, a switching signal is generated every phase difference θ/2N mentioned above from a rotation angle signal from an angle generator provided on a spindle that rotates each disk, and this switching signal causes magnetic The head is sequentially switched and connected to a servo writer, and servo information is set in the disk sector corresponding to the connected magnetic head.

In controlling the position of the magnetic head group relative to the disk pack using the above servo information, the magnetic heads are sequentially switched and connected to the control section using the above switching signal, the sector servo information is read out, and the carriage mechanism is moved.

[Operations] The operation of the servo information setting method of the present invention will be explained with reference to FIGS. 1(a) to (C). In figure (a), convenience L1
Only the data portions on the front side of N magnetic disks I-1, 1-2, . . . N are shown. The angle O of each sector of each data plane is one-eighth of the total circumference 360@.

Sector S of each data plane in the figure! s + Sl 3・
...81, 2N-1 has an angle of 0 in the order of the disks
The phase is shifted by 7N (only the surface side is shown),
The sectors of each data portion have a phase difference of θ/2N as a whole. Sector servo information Ml sM2 at the beginning of each sector
...M2N is set. Figure (b) is an expanded view of the sector servo information for one track (between indexes: INDEX) in each data section, and the servo information M111 Ml 2...Ml during the length of l sector.
+2N in succession at appropriate intervals, which cycles through one track. Each servo information M is followed by sector information and a data section. Figure (C) shows a readout signal for sector servo information M, which consists of a pulse train MO, M+ for generating an AGC signal for automatic gain control and clock pulses for position control and data demodulation.

In the following, the length of the sector servo information M must be shorter than each phase difference of 0/2N, and if it exceeds this, the length cannot be set. However, as will be described later, during reading, the servo information of each disk is continuous at a certain interval, so the length should be adjusted to meet the above conditions in consideration of this.

When writing sector servo information NM, stop the movement of the head group and use the angle signal from the angle generator to determine the phase difference 0/
A switching signal is generated every 2N, and at the timing of this signal, the head is switched and connected to the servo writer, and servo information is sequentially written into each sector. Therefore, one rotation of the spindle completes writing to one track on both the front and back sides of the entire disk. In the conventional sector servo method, 2N rotations were required for one track on the front and back sides of the entire disk, but the writing time is much shorter.

Next, in data occupancy/reading, the heads are switched and connected to the control section using the above switching signal, and the position of the head group is controlled based on the read sector servo information. In this case, writing/reading data for any one sector] 1. Since the servo information is used 2N times, head position control is more accurate than conventional control of only the front of the sector, and , the clock pulse for data demodulation is more stabilized.

[Embodiment] FIG. 2(a) shows a block configuration of the main parts of an embodiment in which the servo information setting force formula according to the present invention is applied to writing servo information of a servo writer and writing/reading data. . However, in practical use, only the necessary parts of the servo writer and magnetic disk device (or inspection device) are applied.

In FIG. 2(a), a disk back 1' is attached to the spindle 3, and N disks l, 12...
- LH rotates at the same time by the spindle motor 3a. The magnetic head group 2' is moved by a drive mechanism 6 such as a voice coil fixed to a moving section 5 of the carriage mechanism. Each head 2 has a changeover switch 4 mounted on the moving part 5.
connected to. The changeover switch 4 includes a servo light switch section for the servo writer 7 and a servo changeover switch section for servo information. Next, the spindle 3 is provided with an angle generator 8, and the rotation angle signal shown in FIG. Switching signals HDold, HDt12, . . . are generated for each phase difference θ/2N.

When writing servo information, a head switching signal is transferred to the switch 4, and the head 2 is sequentially switched by the servo switching switch and connected to the servo writer 7, and the servo information is written to the sectors of each disk with a phase difference of θ/2N. are written sequentially at the beginning of When writing to one track of each disk is completed, a drive signal is applied from the servo writer 7 to the drive mechanism 6, and the head moves to the next track position. The circuit configuration and explanation necessary for controlling movement between tracks in this case will be omitted.

Next, in data occupancy/reading, the head 2 is switched by the switching signal in the same way as above, and the servo information read by the head is adjusted to a constant level by the AGCAMPII, and the low-pass filter (LPF + 2
Unnecessary harmonics are cut, and an integral circuit is added! 3
After the waveform is integrated by , two sample and hold circuits (SAMP) 14a and 4b are manually operated to hold the pulse train MO9M1 of servo information. The sample and hold timing is determined by detecting the peak of the output signal of the LPFI 7 with the peak detector 17, controlling it with the gate circuit I8 using the switching signal, and generating and supplying it with the sampling pulse generating circuit I9. Here, the gate control using the switching signal is performed in synchronization with the servo information in order to eliminate unnecessary signals other than this.

The pulse train M obtained by Control 4r+"J is created, and the drive mechanism 6 is operated to position the head. Furthermore, a clock pulse for data demodulation is generated by a phase-locked oscillator (PLL) circuit from the pulse trains MO and Ml, and this A detailed explanation of the configuration and operation of the PLL circuit will be omitted.

[Effects of the Invention] As is clear from the explanation below, in the magnetic disk servo information setting force formula according to the present invention, the sector angle θ is 2N (N Sector servo information is set sequentially with a phase difference of 1/(number of disks), and writing of servo information is completed in one rotation of the disk for one track on both the front and back sides of all disks. The time is much reduced compared to the conventional sector servo method. Also,
When writing/reading data to/from the disk, 2N servo information operates for one sector, making head position control more accurate and clock pulses for data demodulation more stable. However, there are significant effects that can be obtained when applied to servo writers for high-density magnetic disks using thin-film heads, magnetic disk devices, or inspection devices.

[Brief explanation of drawings]

FIGS. 1(a), (b), and (C) are explanatory diagrams of the effect of sector servo information in the magnetic disk servo information setting method according to the present invention, and FIGS. 2(a) and (b) are diagrams of the present invention. Figure 3 (a) is a block diagram of an embodiment in which the servo information setting method for magnetic disks is applied to a servo writer and a magnetic disk device (or @ negative device).
) and (b) are explanatory diagrams of the track sector of the magnetic disk and the positional relationship of the magnetic head with respect to the track, and FIGS. 4 (a) and (b) are the servo system and servo information for the disk pack. An explanatory diagram of
FIG. 5 is an explanatory diagram of a conventional data-sector servo system for a disk pack. ■... Magnetic disk, 1'... Disk pack, 2... Magnetic head, 2'... Magnetic head group, 2a... Carriage mechanism, 3... Spindle, 3a... Spindle motor , 4... Changeover switch 5... Moving part of carriage mechanism, 6... Drive mechanism, 7... Servo writer, 8... Angle generator,
9...AMP, +o...Head switching signal generation circuit,...AGCAMPl 12...LPF. 3... Integrating circuit, 14... Sample hold circuit,
5... Differential amplifier, 16... Carriage control section, 7
...Peak detector, 18...Gate circuit, 9...
Sampling pulse generation circuit.

Claims (3)

[Claims] (1) In the data surface sector servo method for a plurality of N magnetic disks (hereinafter simply referred to as disks) constituting a disk pack, each track of each disk is equally divided into a plurality of s sectors, and each track of each disk is divided into a plurality of s sectors. With respect to the angular position of each sector on the front and back surfaces, a phase difference θ of 1/2N, the number of data surfaces of the disk, of the angle θ (=360°/s) formed by the equally divided sector.
/2N is provided, and sector servo information is set at the beginning of each sector. (2) A switching signal is generated for each phase difference of 0/2N based on a rotation angle signal from an angle generator provided on a spindle that rotates each of the disks, and the magnetic head is sequentially switched using the switching signal. 2. The magnetic disk servo information setting method according to claim 1, wherein the magnetic disk servo information setting method is connected to a servo writer and sequentially writes the sector servo information in sectors on the disk surface corresponding to the connected magnetic head. (3) In response to the switching signal, the magnetic head is sequentially switched and connected to the control unit to read the sector servo information, and based on the read sector servo information,
3. The servo information setting method for a magnetic disk according to claim 1, wherein the position of the magnetic head group with respect to the disk pack is controlled by controlling movement of a carriage mechanism.