JPH0224879A - Disk device - Google Patents

Abstract

PURPOSE:To perform the optimum tracking servo to disks having different numbers of sectors by counting the number of tracking patterns of a disk and setting a calculated content to the servo constant corresponding to the number of sectors of the disk. CONSTITUTION:When a magnetic disk is rotated, a counter which counts servo signals D is initialized and the pattern of the servo signals is detected from the output of a comparator 14 by detecting index signals at every turn of the disk. The count value of the counter is increased by +1 whenever the pattern of the servo signals is detected. Then the number of sectors is discriminated at the next index signal detecting time and tracking servo is performed by setting the constant corresponding to the discriminated number of sectors. After discriminating the number of sectors, the sampling frequency of a head position controlling system is changed so that the sampling frequency can correspond to the detecting timing of the servo signal pattern and values of a head driving system and tracking error signal detecting system are optimized. At the time of optimization, a ROM in the CPU 15 is referred to. When such constitution is used, the tracking servo can be performed certainly by automatically detecting the number of sectors.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a disk device that performs head tracking servo by detecting a servo signal pattern formed on a data recording surface.

[Conventional technology]

2. Description of the Related Art In recent years, high-density recording has been rapidly progressing in disk drive devices as well as recording media, and along with this, the density of recording tracks has also been increased.

This high-density recording requires high precision in controlling the position of the head on each track, so a servo signal for tracking is recorded on the recording surface, and while detecting this tracking signal, the position error of the head with respect to the track is detected. Systems that detect and track the head have come to be adopted.

Various types of servo signal patterns can be considered, but a so-called sector servo system, in which servo signal patterns are formed between a plurality of sectors constituting a recording track on a recording medium, is common.

[Problem that the invention is trying to solve] However,
In the conventional example described above, since tracking servo is performed on a disk medium having a specific number of servo patterns, there is a drawback that tracking servo cannot be performed correctly on a disk medium having a different number of servo patterns.

This is because tracking is performed by performing servo calculations using a sampling servo based on the predetermined number of servo patterns per rotation, so if the number of servo patterns changes, the number of samplings changes, and the internal constants of servo calculations are all different. This is because tracking servo cannot be performed on media with different formats under the same conditions.

[Means for solving problems]

The present invention has been made to solve the above-mentioned problems, and is characterized by a disk device having a servo means that performs tracking using a plurality of servo signal patterns formed on a data recording surface. a determining means for determining the number of the servo signal patterns detected during one rotation of the disk, and changing setting conditions of the tracking servo means corresponding to the number of servo signal patterns according to the determination result of the determining means. A disk device is provided with a control means for controlling the disk drive.

[Effect]

As a result, even if disks with different numbers of sectors per track, that is, different numbers of tracking servo signal patterns, are used together, the format of each disk can be automatically determined, and optimal tracking control can always be performed for any disk. .

〔Example〕

Hereinafter, one embodiment of the disk device according to the present invention will be described in detail with reference to FIGS. 1 to 4.

FIG. 4 is a diagram for explaining the recording track pattern of the magnetic disk used in the disk device of the present invention.
A recording track TOO consisting of sectors.

TOI, TO2, . . . are formed concentrically, and a tracking servo signal S is formed between each sector in each track. Each servo signal has a different frequency 'I
It is composed of servo patterns S, , S2 consisting of '2.

FIG. 2 is a block diagram of a servo system circuit showing one embodiment of the disk device of the present invention, and FIG. 3 is a signal waveform diagram of symbol ANE in FIG. In FIG. 2, DI is a magnetic disk, 1 is a magnetic head, 2 is an amplifier that amplifies the output of the magnetic head 1, 3 is a read data reproduction circuit, 4 is an AGC circuit,
5 and 6 are amplifiers that amplify the output signal of the AGC circuit 4, and 7
- is the r1 resonator that resonates with the frequency f1 of the servo signal S1, *The life is the f2 resonance adder that resonates with the frequency f2 of the servo signal S2, 13 is the detector, and D is its detection output, which is fed back to the AGC circuit 4. and operates to keep the reproduction amplitude constant. 14 is a comparator for waveform shaping, and 15 is a CPU that controls a sample hold circuit, an A/D converter, and a D/A converter, which will be described later, based on the signal supplied from the comparator 14.

16 is a sample hold circuit that samples and holds the output signal of the differential amplifier 11 based on a command from the CPU 15, 17 is an A/D converter that converts the sampling data E of the sample hold circuit 16 into digital data, and 18 is from the CPU 51. A D/A converter that converts the output head position control signal into an analog signal, 19
is a power amplifier that amplifies the power of the output signal of the D/A converter 18 and drives the head position control actuator 20. Also, 21 is a disk rotation motor, 22 is a CP
This is a motor drive circuit that drives the motor 21 based on the command from U15.

Here, when looking at the transmission system of the head drive system for moving the magnetic head l in the width direction of the track, the signal for detecting tracking errors is formed intermittently on the disk and is not continuous. , the transfer system is a sample value control system. This system is shown in FIG.

The figure shows a transmission system for controlling the head position, which has been subjected to Z conversion. In the figure, r(t) is the head position target value, C(t) is the reproduction signal output from the head, and C*
(t) is a sample value of the head output, G (s) is a transfer function of the head drive system, and H(s) is a transfer function of the tracking error detection system. If the transfer function of this entire system is expressed as a two-transformed system, it becomes as follows.

Therefore, as the number of sectors on the track, that is, the number of tracking signals, changes, the sampling frequency of this system changes, so starting with c*(t), G,
The coefficient of H, setting conditions, etc. must be changed. In other words, this sampling frequency is determined by the number of tracking signal patterns detected during one rotation of the disk,
In the figure, by adapting the opening/closing period of the switch Sa to the detection period of the tracking servo signal pattern, a stable system can be realized without causing errors.

The servo system block of this embodiment has the above-mentioned configuration, and its operation will next be explained with reference to the waveform diagram shown in FIG. 3.

The motor drive circuit 22 drives the motor 21 to rotate the magnetic disk DI at a predetermined speed, thereby driving the magnetic head l.
By moving and accessing a desired recording track by the actuator 20, the recorded data signal on the track is reproduced. The reproduced read data is sent to amplifier 2.
The read data is decoded and supplied to the AGC circuit 4, where the reproduction level is controlled to be constant by an operation described later. The reproduced signals output from the AGC circuit 4 are respectively supplied to amplifiers 5.6. In the servo signal area S on the recording track, the reproduction output of the magnetic head l is a mixture of components of frequency fl+'2, and then
f1 resonator 7. Each frequency component is extracted separately in the f2 resonator 8, and the detector 9. The third
DC level signal A as shown in figures (a) and (b),
It is output as B. In other words, the output signal A of the detector 9
gives a voltage proportional to the frequency f and the acid component in the servo region on the recording track, and the output signal B of the detector 10 similarly gives a voltage proportional to the frequency f2 component in the servo region. These output signals are compared by a differential amplifier 11, and a signal C corresponding to the difference is output (FIG. 3(C)). The level difference between the output signals A and H is that the head L has the servo signal pattern S.

Based on the difference in the area traced for each S2, this becomes a position error signal representing the amount of positional deviation of the head l with respect to the reproduction track.

In addition, the frequency 'I+f2 of the servo signal pattern S, , S2
By setting both to less than half of the lowest frequency of the data area, the fI+'2 component is not detected in the data area.

On the other hand, the outputs of f, resonator 7, and f2 resonator 8 are each added by an adder 12, and then converted by a detector 13 to a DC level signal D (FIG. 3(d)), which is then sent to the AGC circuit 4. Feedback will be given. That is, AGC is applied so that the signal level of the sum of the reproduction output levels of each servo signal pattern Sl and S2 in the servo area is kept constant.

In the device of the present invention, since the output signal of this detector is generated only in the servo area, it is used as a signal to detect that the head l has entered the servo area S and also to detect the number of sectors on the track. ing. That is, after the output signal is waveform-shaped by the comparator 14, the CPU 15
supply to. After a certain period of time necessary for the position error output signal C of the differential amplifier 11 to become stable after this signal is input, the CPU 15 issues a sampling command to the sample and hold circuit 16 to obtain a stable differential signal. The position error signal of the amplifier 11 is sent to the sample hold circuit 16.
is sampled and held, and an output signal E is obtained (third
Figure (e)).

Since the output signal of the detector 13 is used as the servo signal area detection timing signal in this way, a special synchronization signal and a circuit for detecting such a synchronization signal are not required, and the configuration is simplified.

The signal E output from the sample hold circuit 16 is A
/D converter 17 converts it into a digital signal, and the CPU
Incorporated into 15. In the example shown in Figure 3, one servo area is sampled and held only once, and one
Although the position error signal data is fetched into the CPU 15 only once, the accuracy of the position error signal data can also be increased by repeating this multiple times and averaging them.

The position error signal taken into the CPU 15 is
The head position control data is converted into head position control data, and after being converted into an analog signal by the D/A converter 18,
The power is amplified by the head positioning actuator 20.
supplied to. This causes the actuator to move the head in the direction where there is no position error, that is, at the frequency fl+
The head position is corrected in the direction in which the levels of each component of '2 are equalized. Therefore, the position of the head 1 is controlled so that it always follows the center line of the data track.

Next, using FIG. 1, even if there are different numbers of magnetic disks on one track of a sector or servo area S, the number of magnetic disks that are different on one track of the sector or servo area S is automatically determined, and the optimum tracking servo control system corresponding to each disk is set. A configuration that allows this to be performed will be explained.

In other words, in this type of device, the number and timing of sampling are set according to the predetermined number of servo signal patterns during one rotation, and servo calculations are performed.
When the number of servo patterns changes, the number of samplings and timing change, and the servo calculation itself cannot be performed under the same conditions. Therefore, internal constants of the servo calculation must be changed according to the number of samplings and timing.

FIG. 1 shows a flowchart of the control means provided in the CPU 15 to automatically set the tracking servo system for a plurality of types of magnetic disks having different numbers of servo signal patterns during one rotation. It is. Furthermore, the description will be made assuming that there are three types of magnetic disks having different numbers of servo patterns: 1 track with 35 sectors, 1 track with 36 sectors, and 1 track with 38 sectors.

At 5 tepl, when the magnetic disk DI is inserted into a disk loading section (not shown), the process proceeds to 5 step 2, where the motor drive circuit 22 drives the disk rotation motor 21 and rotates the magnetic disk DI.

Subsequently, in step 5, a servo pattern counter that counts the number of servo signal patterns S during one rotation of the magnetic disk is initialized.

At step 54, an index signal generated once per revolution of the magnetic disk is detected, and in response to the detection of the index signal, a servo signal pattern is detected by the output of the comparator 14 in the circuit shown in FIG. 2 described above.
5) Increase the servo pattern counter by 1 each time it is detected.
(step 6) o Then, when the next index signal is detected in step 7, the count value of the servo pattern counter at that time will be 35 (number of sectors 35), 36 (number of sectors 36), or 38 (number of sectors 38). After determining whether or not the number of sectors is the same and setting constants in the CPU 15 corresponding to the number of sectors according to the determination results, the process moves to the tracking servo processing routine and performs the tracking servo operations shown in FIGS. 2 and 3 described above ( s t e p 8~
s te p 14).

After the number of sectors is determined, the sampling frequency of the head position control system (opening/closing period of switch Sa) shown in Fig. 5 is changed so that the sampling frequency of the system corresponds to the detection timing of each tracking servo signal pattern. In addition, the G and H coefficients of the head drive system and tracking error signal detection system are changed to optimal values so that the stability and responsiveness of the system are set conditions according to the sampling frequency.

These optimal values are determined by how the stability and responsiveness of the system are set, so although they are not generally specified conditions, they should be determined as appropriate during design, and the CPU
This is stored in the ROM in 15.

As a result, even if a disk with a different number of sectors is loaded, it can be automatically detected and reliable and stable tracking servo can be performed.

Note that if the count value of the servo pattern counter is not any value, the process returns to 5tep4 and detection is performed again. If a certain number of times cannot be detected, an error message or the like may be output to indicate that the magnetic disk DI is unusable, and access may be stopped.

This makes it possible to detect the index signal detection interval, that is, the number of servo signal patterns S during one rotation of the disk, even if disks with different numbers of sectors in one track, that is, the number of servo signal patterns S, are used together. However, it is possible to always set the internal constants and the like of the digital servo calculation to optimal values based on the sampling numbers and sampling timings that differ in each case, and the timings that change depending on the sampling numbers.

In addition, according to the above-mentioned embodiment, disks with different numbers of sectors were explained using disks with 35 sectors, 36 sectors, and 38 sectors as examples, but the invention is not limited to these, and each setting value can be set at the time of design. If you prepare the following, a wider range of options will be possible.

Further, in this embodiment, the disk medium is determined by counting the number of servo patterns during one rotation, but the same determination can be made by measuring the time gap between servo patterns using a timer. The timer used in this case is built into the CPU (8-bit one-chip CPU, etc.).

Furthermore, although this embodiment has been explained using a magnetic disk as an example,
The present invention can be applied to any medium and device using a so-called sector servo system.

〔Effect of the invention〕

As explained above, by using the CPU and circuit configuration conventionally built into the drive device itself, the number of tracking patterns on the disk is counted through signal processing by these circuits, and the servo constant corresponding to the number of sectors is determined. By setting the calculation contents, optimal tracking servo can be performed for disks with different numbers of sectors without increasing cost.

[Brief explanation of the drawing]

FIG. 1 is a flowchart for explaining the automatic discrimination and control means of the tracking servo system in the disk device of the present invention, FIG. 2 is a block diagram showing an embodiment of the device of the present invention, and FIG. FIG. 4 is a diagram for explaining a track pattern on a disk used in the apparatus of the present invention, and FIG. 5 is a diagram showing a head drive control transmission system. S・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・ Servo signal pattern DI・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・・・・
......Magnetic disk Too, TOI
, TO2・・・・・・・・・・・・・・・・・・
・・・・・・Recording track patent applicant Canon Electronics Co., Ltd.

Claims (1)

[Claims] A disk device having a servo means for performing tracking using a plurality of servo signal patterns formed on a data recording surface, comprising: a determining means for determining the number of the servo signal patterns detected during one rotation of the disk; and control means for changing the setting conditions of the servo means corresponding to the number of servo signal patterns according to the determination result.