JPH0594674A - Disk medium and disk device - Google Patents

Abstract

PURPOSE:To provide a disk medium having a servo format in which a capacity increase is maximum in the case of applying a ZBR method to a sector servo system. CONSTITUTION:In the disk medium in which all data tracks are divided into plural zones 6 to 8, data recording and reproducing frequencies are the same within a zone and different among different zones, and a servo sector is formed on the same surface as the data, the prescribed number of the servo sectors 2 are formed at an isometric position with an isometric spacing in the same zone, and simultaneously, the data sector group 3 is formed so that the group 3 is held between the servo sectors 2. In a zone boundary areas 5 where the recording and reproducing of data between adjacent zones are not performed, the servo sectors for which the positions of adjacent zones are at least partly overlapped in a track direction, are formed to the center of a disk radius direction in the zone boundary areas, and the servo sectors which are not overlapped are formed extendedly to the proximity of the adjacent zones.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk medium such as a magnetic disk or an optical disk and a disk device for recording / reproducing data using the disk medium, and more particularly to recording data by dividing a track into several zones. The present invention relates to a disc medium and a disc device that have the same reproduction frequency in tracks in the same zone and are different in each zone.

[0002]

2. Description of the Related Art Generally, in a conventional disk device, for example, a magnetic disk device, data is recorded at the same recording frequency on all tracks on the disk from the inner circumference to the outer circumference. In this case, since the length of one track circumference on the disk medium (hereinafter, simply referred to as a disk) varies depending on the radius of the track, the recording wavelength of data becomes longer at the outer circumference than at the inner circumference. The recording wavelength of the data on the innermost track is the shortest, which corresponds to the maximum linear recording density on the disc.

In recent years, in order to improve the storage capacity of a disk, a constant linear density (Constant Linear Density: hereinafter referred to as C
Zoned bit recording (ZBR method), which is a type of LD method), has come to be adopted. In the ZBR system, all tracks are divided into some zones. For example, when the total number of tracks is 1,000, if the zones are divided into four zones, the first zone is tracks 0 to 249, the second zone is tracks 250 to 499, and the third zone is track 5.
00-749, and the fourth zone is divided into tracks 750-999. The recording frequency of the data recorded on all the tracks in one zone is the same, but the recording frequency of the data is set higher toward the outer peripheral side zone, and the maximum linear recording density of the data in each zone ( This is a method of recording data so that the shortest recording wavelength) becomes equal. In the ZBR system, when one track corresponds to one zone, the CLD system is obtained.

According to the ZBR method, the storage capacity per track increases as the tracks included in the outer peripheral zone increase, and the total storage capacity of the disk increases. For example, recording area = radius 17.740 mm to 31.036 mm, track density = 2,117 TPI (track pitch = 12 μ
m: number of tracks = 1109), maximum linear recording density in the zone = 70 kBPI, sector capacity = 1,200 B In the case of a fixed magnetic disk device, if the number of zones is 2, the first
It is designed as shown in the table.

(Table 1) Zone innermost track Maximum line recording number Center radius (mm) Track number Track number Sector number Density (kBPI) 1 17.740 0 to 553 554 32 70.00 2 24.388 554 to 1108 555 44 70.02 ZBR system The storage capacity per disk surface when not using is 42.59 MB, but using the ZBR method of dividing into two zones as described above, the storage capacity per disk surface is 50.58 MB, and the capacity is approximately 19% increase. This storage capacity increases as the number of divided zones increases.

On the other hand, as a tracking servo system in this type of disk device, there is no thermal off-track,
Further, particularly in a small-sized disk device having a small number of disks, a sector servo system having a better format efficiency than the servo surface servo system has come to be used. In the sector servo system, servo information for head positioning is formed in a partial area of a sector, and head positioning is performed by sample value control based on the servo information obtained every sector cycle. In this case, an area in which data is recorded within one sector is called a data sector, and an area in which servo information is recorded is called a servo sector.

A conventional example in which the ZBR method is applied to a disk device using the sector servo method as a tracking servo method will be described with reference to FIG.
As shown in FIG. 9, in the conventional disk medium, the servo sectors are formed at the same angular position over all tracks regardless of the zone, as in the case where the ZBR method is not used. Therefore, the number of servo sectors is the same in all tracks, and the recording frequency of the servo pattern formed in the servo sectors is also the same. This is because when the number of servo sectors is changed for each zone, it becomes difficult to detect the servo sector when the zone changes as the head moves. Therefore, one or more data sectors are provided for the servo sectors so that the servo sectors do not straddle adjacent servo sectors (the data sectors between the servo sectors are referred to as a data sector group). Further, the data sectors are provided so that the number of sectors increases toward the outer peripheral side zone.

However, in such a conventional method, Z
When the number of sectors in the data sector group is optimized in order to maximize the capacity increase by the BR method, there arises a problem that the number of servo sectors decreases. For example, Table 2 shows a design example when the minimum value of the number of sectors in the data sector group (the number of sectors in the innermost zone) shown in FIG. 9 is 2. Here, in order to correspond to the example shown in Table 1, the number of zones = 2, the sector capacity = 1,200 B, and the maximum linear recording density of each zone is 70 kBPI.

(Table 2) Zone Innermost track Maximum line recording number Center radius (mm) Track number Track number Sector number Density (kBPI) 1 17.740 0 ~ 738 739 32 70.00 2 26.608 739 ~ 1108 370 48 70.01 One side of disk The storage capacity per unit is 49.69 MB, which is increased by about 17% as compared with the case where the ZBR method is not used. At this time, the number of servo sectors is 16. next,
Consider the case where the capacity is maximized when divided into two zones. The number of data sectors in the inner zone shown in Table 1 is 32, and the number of data sectors in the outer zone is 44.
Is the case. As described above, the storage capacity per disk surface is 50.58 MB, and the capacity is increased by about 19%.
However, the number of servo sectors becomes 4, which is the greatest common divisor of the data sector numbers 32 and 44 in the inner and outer zones.

[0010]

As described above, in the conventional technique, if the ZBR system is simply applied to the disk device using the sector servo system, the number of servo sectors becomes the greatest common divisor of the number of data sectors in each zone. There is a problem that the number of servo sectors is smaller than the number of data sectors.

Further, if the number of servo sectors cannot be designed independently of the number of data sectors, and if the number of data sectors is optimized so that the capacity is maximized for a certain number of zones, the desired number of servo sectors cannot be obtained. Generally, the number of servo sectors decreases as the capacity is optimized.

In the sector servo system, the smaller the number of servo sectors, the lower the sampling frequency, and the head positioning control performance such as tracking performance and seek performance deteriorates. Therefore, such a reduction in the number of servo sectors becomes a problem. For this reason, conventionally, in order to secure a certain number of servo sectors, it has not been possible to design the number of servo sectors that can maximize the capacity increase by using the ZBR method.

It is an object of the present invention to provide a disk medium having a servo format which maximizes the capacity increase when the ZBR method is applied to a disk apparatus using the sector servo method, and a disk apparatus using the same. To do.

[0014]

DISCLOSURE OF THE INVENTION In a disk medium according to the present invention, all data tracks are divided into a plurality of zones each including a predetermined number of data tracks continuous in the disk radial direction, and data is recorded in one zone. In a disk medium having the same reproduction frequency, different data recording / reproduction frequencies in different zones, and a servo sector having servo information for head positioning formed on the same surface as the data, a predetermined number of servo sectors in the same zone. Are formed at equal angular positions at equal angular intervals,
One or more data sectors are formed so as to be sandwiched between the servo sectors, and a zone boundary area in which no data is recorded is provided between the adjacent zones. Within the zone boundary areas, the servo sector positions of the adjacent zones are in the track direction. The first servo sector which at least partially overlaps is formed up to the center of the zone boundary area in the disk radial direction, and the second servo sector which does not overlap is adjacent to the zone adjacent to the zone having the second servo sector with the zone boundary area interposed therebetween. It is characterized in that it is formed to extend up to.

The angular positions of the servo sectors formed at equal angular intervals do not always match between different zones. At least one data sector is formed between servo sectors.

Further, the disk apparatus of the present invention using such a disk medium, means for decoding the servo information read by the head from the disk medium and reproducing it as a servo signal, and the servo signal reproduced by this means. From the disk medium, a means for identifying a zone in which a head is present, a means for identifying a servo sector in the identified zone, and a means for extracting a servo sector candidate to be detected next that appears following the identified servo sector. And a means for determining a servo sector to be detected next from the extracted servo sector candidates to be detected next, and a means for detecting the determined servo sector.

[0017]

In the disk medium of the present invention, since it is not necessary to set the number of servo sectors to the greatest common divisor of the number of data sectors in each zone, the maximum linear recording density of data can be designed to be substantially equal in all zones. Further, the number of servo sectors can be formed up to the number equal to the number of data sectors.
There is no reduction in the number of servo sectors by using the R method.

Further, since the first and second servo sectors are formed in the zone boundary area in the above-described manner, the servo sector can be detected reliably.
That is, when the head is located exactly on the center of the zone boundary area in the disk radial direction (referred to as zone boundary), the first servo sector existing only up to the zone boundary may not be detected correctly. The second extending beyond the zone boundary to the vicinity of the adjacent zone
The servo sectors of are easily detected correctly. On the other hand, if the head is located exactly at the end of the zone boundary area in the radial direction of the disk, the second servo sector that ends near the end of the zone boundary area may not be detected correctly. The first servo sector extending beyond and to the zone boundary is easily detected correctly.

Since the disk medium of the present invention has a different servo sector sampling period for each zone, it is necessary for the disk device to devise how to detect the next servo sector after a certain servo sector is detected. .. Therefore, in the disk device of the present invention, first, the position of the head is identified by the servo signal obtained from the servo information on the detected servo sector, and the zone in which the servo sector now detected from the head position is identified, The sector number within the zone of the servo sector is identified.

Further, a candidate of a servo sector to be detected next is obtained from the identification information of the detected servo sector.
For example, the servo sector to be detected next is a servo sector that sequentially appears in time with the rotation of the disk. Therefore, for example, the appearance time of each servo sector is tabulated in advance from the layout relationship of the servo sectors on the disk medium, and the appearance time The servo sector candidate to be detected next can be obtained from the size relationship.

The position of the head at the appearance time of the servo sector candidate to be detected next obtained in this way is obtained, and if it coincides with the zone of the servo sector, it is determined as the servo sector to be detected next. For example, after detecting a servo sector in a certain first zone, it was found that the first appearing servo sector was the servo sector in the first zone, and the position of the head at that time was required to be in the same first zone. At this time, the servo sector to be detected next is determined to be the servo sector of the first zone.

Further, after detecting the servo sector in a certain first zone, it is found that the servo sector which appears first in time is the servo sector of the second zone, and the position of the head at that time is in the first zone. If it is required that the servo sector to be detected next is not the servo sector, the same operation is performed on the servo sector appearing next to the servo sector in the second zone, and the servo sector to be detected next is detected. It is decided whether or not.

However, the servo sector to be detected next is a servo sector (first servo sector, but not completely overlapping) which partially overlaps in the zone boundary area, and the position of the head at the servo sector appearance time is the zone boundary area. If it is within the range, the detection is not performed, and the servo sector (second servo sector) that appears next in time is subjected to the same processing to determine whether or not the servo sector should be detected. If it is determined that the servo sector should be detected, the detection operation is started immediately before the servo sector is read by the head, and the servo sector is detected.

Further, by dividing the difference between the position of the head and the position of the head in the servo sectors which are continuously detected in this way by the detection time interval between them, the moving speed of the head can be continuously determined, and based on this, the head moving speed can be determined. The seek control can be smoothly performed.

Furthermore, in the present invention, the track following control system has different sampling periods for each zone, but by adjusting the stability indexes such as the phase margin and gain margin of the transfer characteristics of the system to be above a certain level. , Stable and highly accurate track following control can be performed in all zones.

[0026]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an arrangement of servo sectors 2 and data sector groups 3 formed on a disk medium 1. The servo sector 2 is an area in which servo information for positioning the head on the data track is formed. The data sector group 3 is composed of one or more data sectors, and is an area in which a data track 15 for recording / reproducing data is formed. In this embodiment, all data tracks on the disk medium 1 are divided into four zones 6-9. Servo sectors are provided at equal angular positions in each zone 6 to 9 at equal angular intervals. However, since the number of servo sectors differs for each zone, the angular positions of the servo sectors do not necessarily match between different zones. Further, one or more data sectors, that is, the data sector group 3 is provided between the servo sectors.

In this case, the recording / reproducing frequency of the data in one zone is the same, but the maximum linear recording density of each zone (the linear recording density of the innermost track in the zone) is designed to be as equal as possible. Therefore, the recording / reproducing frequency of data is different for each zone.

FIG. 2 is a detailed view of the portion A shown in FIG. 1, mainly showing the arrangement of servo sectors and data sectors (groups) in the zone boundary area 5. Zone boundary area 5
Is an area where data is not recorded / reproduced over several tracks,
That is, it is an area without a data sector group.

Here, the arrangement of the servo sectors in the zone boundary area 5 is set as follows. First, when the servo sectors of the adjacent zones in the zone boundary area 5 are at an angular position where they at least partially overlap each other, for example, the servo sectors 10 and 11 (first servo sectors) in FIG. It is provided until the two come into contact with each other at the center position in the disk radial direction). Further, when the servo sectors of the adjacent zones are at an angular position where they do not overlap at all, for example, the servo sectors 12 and 13 (second servo sector) of FIG. It is formed so as to extend beyond the zone boundary 14 to the vicinity of the adjacent zones with the layer 5 interposed therebetween.

FIG. 3 is a block diagram of a disk device for recording and reproducing data using the above-mentioned disk medium.
In FIG. 3, 101 is the above-mentioned disk medium, for example, a magnetic disk. In this disk device, a spindle motor 102 that rotates a disk medium 101 as a mechanical unit, and servo information formed in the servo sectors set on the disk medium 101 as shown in FIGS. A head 103 for recording / reproducing data, and an actuator 10 for moving and positioning the head 103 to a desired track.
4 is provided. The actuator 104 includes a carriage 105, which is a movable portion, and a voice coil motor (VCM) 106 for generating thrust. Although a linear actuator is used as the actuator 104 in this figure, a rotary actuator may be used.

On the other hand, the circuit portion for positioning the head 103 reproduces the servo information read by the head 103 from the servo sector as a servo signal, and also reads / writes (records / reproduces data in / from the data sector area. (R / W) circuit 107, servo sector detection circuit 1 that outputs a servo sector detection signal when a signal matching the pattern indicating the beginning of the servo sector is detected from the reproduction signal
08, a peak hold circuit 109 for detecting and holding the peak value of the servo signal reproduced in the servo sector area in synchronization with the servo sector detection signal, A / D conversion for digitizing the peak-held servo signal and loading it into the μCPU 111 Of the position and movement speed of the container 110 and the head 103 on the disk medium 101, detection of a track following error during track following and generation of a position control signal for track following, speed error with a rotation speed curve during seek ΜCPU 111, memory 112, position control signal and speed control signal output D / A converter 113, and VCM
It is composed of a driving current amplifier 115.

It should be noted that phase and gain compensation is performed during track following control so that a stable closed loop servo system is achieved, and gain compensation is also performed during seek control.
The compensation filter for performing these compensations is the μCPU 11
1 is implemented as a digital filter.

Next, the outline of the servo sector detection procedure in this embodiment will be described with reference to the flowchart of FIG.

When the servo sector detection operation is started (S
0), the servo information is decoded and the servo signal is reproduced after the head first comes to the head of the servo sector (S1, S
2). The head position is identified from this reproduced servo signal (S3), the zone in which the head is present is identified from the obtained head position information P ₁ (S4), and the sector number of the servo sector in the identified zone is determined. It is identified (S5).

Thereafter, the head moving speed V is calculated as described later (S6), and the servo sector to be detected next is determined (S7).

Next, the servo sector detection method in this embodiment will be described in detail by setting a concrete disk device model. The specifications of the disk medium are: recording area = radius 1
7.740 mm to 31.036 mm, track density = 2,1
17 TPI (track pitch = 12 μm, number of tracks = 1,109), maximum linear recording density of day in zone 7
0 kBPI, disk rotation speed = 3,600 rpm, zone number = 4, number of servo sectors in the first, second, third and fourth zones =
32, 38, 44, 50, sector capacity (capacity of data conversion that can be stored when one round of the disk is divided by the number of servo sectors) = 1,200 bytes. Here, regarding the allocation to the data sector group having a sector capacity of 1200 bytes and the servo sector, about 10% of the sector capacity is allocated to the servo sector.

If the servo information recording / reproducing frequency is constant in all zones, the data conversion capacity of the servo sector (the ratio of the servo sector to the sector capacity) increases toward the outer zone. Further, the relationship among the innermost track position, track number, track number, sector number and maximum linear recording density of each zone is designed as shown in Table 3.

(Table 3) Zone innermost track Maximum line recording number Center radius (mm) Track number Track number Sector number Density (kBPI) 1 17.740 -15 ~ 261 277 32 70.000 2 21.064 262 ~ 538 277 38 70.01 3 24.388 539 to 816 278 44 70.02 4 27.724 817 to 1093 277 50 69.99 First, the initial detection of the servo sector is performed in the zone in which the reference track for initially positioning the head is provided. If the first servo sector is detected in the zone, the detection of the next servo sector starts from the time immediately before the appearance of the next servo sector.
That is, one rotation cycle of the disk is T _r and the number of sectors is S _n.
Then, the next servo sector detection is started after a time shorter than the servo sector period T _r / S _n has passed, and the detection operation is not performed until then. This is to prevent erroneous detection of servo sectors in the data sector section as much as possible. When such a servo sector detection operation is repeated normally for a certain period of time, the initial detection is regarded as successful, and then the head is positioned on the reference track in the same zone.

For example, in the present embodiment, the reference track #
T _r / S when performed in the first zone with 00
The detection of the next servo sector is started immediately before the appearance of the next servo sector, which is a time shorter than _n = 16.67 msec / 32 = 0.52 msec. Then, after the normal servo sector detection is performed, the head is positioned on the reference track # 00.

When the head is set on the reference track # 00, the disk device becomes ready for head access to the target track for recording / reproducing data. The head access to the target track is performed based on the position of the head on the disk medium obtained from the servo information formed in the servo sector.

Next, detection of a servo sector during head access control will be described. First, when a servo sector is detected in a certain zone, a method of identifying the servo sector in which zone the servo sector is detected and which servo sector is detected (process of S5 in FIG. 4) will be described.

The zone in which the servo sector is detected can be obtained from the position of the head obtained from the servo information of the servo sector. For example, if it is found from the servo information that the head is located near the 270 track, it is known that the servo sector is detected in the second zone.

The identification of the numbered servo sector of the detected servo sector can be performed together with zone identification by adding sector identification information to the servo information of the servo sector and reproducing it.

As another method, as shown in FIG. 1, only one servo sector in each zone is formed at the same angular position over the inner and outer circumferences, and information for identifying only this reference servo sector is formed in the servo sector. Then, when the reference servo sector is detected, a timer is operated from then on to measure the time until the servo sector is detected.

The appearance time of each servo sector is tabulated in advance as shown in FIG. 5, and the servo sector having the closest time from the detection of the reference servo sector measured by the timer to the time when the servo sector is detected is found from this table. By doing so, it is possible to identify the servo sector. Further, by using the clock of the timer which is generated in synchronization with the rotation of the disk, more accurate identification can be performed. For example, an output signal of a PLL (Phased Look Loop) circuit that uses an FG pulse generated according to disk rotation and used to control disk rotation as a reference input signal may be used as a clock.

Detection of the servo sector as described above (hereinafter,
The procedure of step S7 of FIG. 4 for detecting the next servo sector (hereinafter referred to as the next detected servo sector) after the identification of the detected servo sector) will be described with reference to the flowchart shown in FIG.

In this case, first, a candidate for the next detected servo sector is obtained (S8). Now, it is assumed that the head is moving from the innermost first zone to the second zone, the detected servo sector is detected in the first zone, and the sector number is # 2. In general, it is extremely unlikely that the head moves to a zone farther than the adjacent zone within the time until the next servo sector is detected, and the next detected servo sector is detected from the same first zone as the already detected servo sector or the head is detected. Zone adjacent to the direction of movement of the head (in this case, since the head is moving toward the outer periphery,
Zone)) is likely to be detected.

If the next detected servo sector is detected from the same zone as the already detected servo sector, if the already detected servo sector number is S _b and the number of servo sectors in that zone is S _n , then (S _b +1) modS _n. Then, the number of the next detected servo sector candidate is obtained. mod is an operator for obtaining a remainder, and (S _b +1) modS _n indicates a remainder when (S _b +1) is divided by S _n . In this case, (2 + 1) mod32 = 3, and # 3 is a candidate for the next detection servo sector.

However, when the detected servo sector is detected from another zone, the servo sector that appears next as the disk rotates is not always # 3. Therefore, a servo sector appearance time table as shown in FIG. 6, which is also used above, is prepared. Detected servo sector (Zone = #
1, sector = # 2) has an appearance time of 0.52, and if the next detected servo sector is detected in the second zone, the first candidate is the first servo sector that appears at a time after 0.52, The appearance time is 0.83, which is # 3.

However, if the appearance time is 0.52 or more, all the servo sectors cannot be candidates for the next detected servo sector, and a certain time such as the processing time of the already detected servo sector or the detection preparation time of the next detected servo sector is taken into consideration. There is a need. For example, if this time is 0.1, then 0.5
Servo sectors that appear at times 2 + 0.1 = 0.62 or later can be candidates for the next detected servo sector.

As described above, when the next detected servo sector is obtained from the size relation of the times in the servo sector appearance time table, or when the already detected servo sector is the final number servo sector, the candidate of the next detected servo sector is the servo sector with the smaller number. .. In that case, a process of adding 1 disk rotation period = 16.67 to the appearance time of the table is required, but using the table as it is makes the process complicated and takes time. Therefore, the relationship between the servo sector appearance times is known in advance, and the next detected servo sector candidates are also known in advance. Therefore, it is more preferable to tabulate them.

FIG. 7 shows an example in which the next detected servo sector candidates in the adjacent zone are tabulated together with the appearance time. As described above, in general, the head hardly moves to a zone farther than the adjacent zone within the time until the next servo sector is detected, so if only the next detected servo sector candidate in the adjacent zone is tabulated. Good. If it is necessary to detect the next detection servo sector in a zone farther than the adjacent zone, at that time, it may be obtained from the magnitude relation of the appearance times as described above. In the table of FIG. 7, the above-mentioned constant time margin is set to 0.1 and the next detected servo sector candidate is determined.

As described above, (S _b +1) m from the same zone as the zone in which the detected servo sector is detected.
The next detected servo sector candidate is extracted by odS _n and from the other zones by the table shown in FIG. 3 or 4. The process of extracting the next detected servo sector candidate is performed in step S8 of FIG.

Next, the process (S9 to S17 in FIG. 5) of finally determining the next detected servo sector from these next detected servo sector candidates will be described. As described above, since it is extremely unlikely that the head will move to a zone farther than the adjacent zone within the time until the next servo sector is detected, the head will be moved to a time corresponding to the time until the next servo sector is detected. Is assumed to be sufficiently smaller than the zone width having the smallest radial width. Therefore, the head does not cross the zone having the smallest radial width within a time corresponding to two to three times the longest servo sector period.

Further, as in the above, the head has the first innermost circumference.
It is assumed that the detected servo sector is moving from the zone toward the second zone and is detected in the first zone. In this case, the next detection servo sector is determined by obtaining the position where the head exists at the appearance time in order from the earliest appearance time among the next detection servo sector candidates in the first zone or the second zone. If the position is in the same zone as the corresponding servo sector, that servo sector may be the next detection servo sector.

FIG. 8 shows some examples of the head locus and the servo sector detection timing. In FIG. 8, the position of the head in the detected servo sector is P ₁ , and the head position in the servo sector with the earliest appearance time among the next detected servo sector candidates is P ₂ , P ₃ , P ₄ ... In order. Figure 8
In (a), the order of appearance of the next detected servo sector candidates is the second →
In the order of servo sectors in the first → second zone,
In the head locus 1, P ₂ is in the second zone, and the next detected servo sector is the first servo sector. In head locus 2, P ₂ is in the first zone, P ₃ is in the second zone, and P ₄ is in the second zone, and the next detected servo sector is the servo sector corresponding to the third P ₄ . In head locus 3, P ₂ is first
In the zone, P _{3 is} also in the first zone, and the next detected servo sector is the servo sector corresponding to P ₃ .

Similarly, in the head locus 1 of FIG.
Servo sectors corresponding to _3, servo sectors, the further head trajectory 3 P ₂ corresponding to P ₂ in the head trajectory 2
Servo sectors corresponding to are the next detected servo sectors.

However, as shown in FIG. 8C, when the appearance times of the next detected servo sector candidates are close and the servo sectors end at the zone boundary (when the servo sectors of the adjacent zones are completely overlapped, If the head position P ₂ or P ₃ at those appearance times is in the vicinity of the zone boundary line (here, it is within the zone boundary area), it is excluded from the next detection servo sector candidates. Therefore, in FIG. 8C, the next detected servo sector is P ₃
The servo sector corresponding to P ₄ is determined instead of the servo sector corresponding to P ₄ . The reason for this is as follows.

Although the servo sector ends at the zone boundary, if the servo information of the servo sector is detected in this portion, the servo information can be read only within the width of the head in the track direction, and erroneous information may be detected. , It is highly possible that the servo sector cannot be detected. Therefore, it is desirable not to detect the servo sector when the head passes through the end of the servo sector in the radial direction. The position includes an error according to the position detection accuracy.
This is because in the case of (c), there is a high possibility that the head will perform servo sector detection at the radial end portion of the servo sector.

However, in the case of P ₂ in the head locus 1 in FIG. 8A or in the case of P ₃ in the head locus 2 in FIG. 8A, the servo sector extends to the zone boundary area in the adjacent zone. Since it is provided, the margin to the radial end of the servo sector is large, and the possibility of erroneous detection of the servo sector is low. On the contrary, the wider the zone boundary area, the more erroneous detection of servo sector detection can be prevented. However, the wider the zone boundary area is, the smaller the data area is. Therefore, the optimum width of this area is equal to or higher than the accuracy of obtaining the position of the head at the next detection servo sector candidate appearance time.

Here, the position P _n of the head at the appearance time of the next detected servo sector is obtained by predicting from the position and speed of the head obtained in the detected servo sector and the time until the appearance time. That is, the predicted head position P _n is P _n = P ₁ + V × T _1n (where P ₁ is the position in the detected servo sector and T _1n is the time interval between the detected servo sector and the next detected servo sector candidate). n: 2,3,4 ...). Here, the velocity V is obtained by dividing the difference between the position P _{1 of} the head obtained in the already detected servo sector and the position P ₀ obtained in the servo sector detected before that by the interval time T ₁₀ of these servo sectors, that is, V
= (P ₁ −P ₀ ) / T ₁₀ .

In this way, the next detected servo sector is determined (S17). When the next detection servo sector is determined, the servo sector detection operation is started immediately before the servo sector appears (S18). The reason why the detection operation is not performed until just before the detected next detected servo sector appears is to minimize erroneous detection due to the servo sector detection in a portion other than the servo sector as described above.
Thus, the servo sector detection operation is performed (S19).

The position P _n of the head at the appearance time of the next detection servo sector can be actually obtained by using a position sensor that gives the displacement of the head together. For example, in FIG. 3, an optical position sensor is provided on the carriage 105 that mounts the head 103. The amount of displacement of the head 103 in the radial direction of the disk medium 101 can be obtained from this optical position sensor. In this case, if the position obtained from the servo information in the detected servo sector is P ₁ , the appearance time interval between the detected servo sector and the next detected servo sector candidate is T _1n , and the head displacement amount T _1n after the detected servo sector is P _vn. , P _n = P ₁ + P _vn (n: 2, 3, 4 ...) The head position P _n is obtained. However, the position P _n of the head in this case is the position immediately before the appearance time of the servo sector. Even if the head position is obtained at the center of the servo sector, the next detection servo sector can be determined,
Since the head has already passed the servo sector, the actual servo sector cannot be detected.

As described above, the servo sector is detected, the servo information contained therein is read, and the head position is identified from the reproduced servo signal (S2 to S3 in FIG. 4). Further, the moving speed of the head is V = (P _p as described above from the positions P _p and P _{b of} two servo sectors which are continuously detected and their time interval T _pb.
It is calculated as −P _b ) / T _pb (S6 in FIG. 4). If a servo sector is detected consecutively in the same zone, T _pb will always be the servo sector period in that zone.

The head access control consists of speed control for moving the head at high speed near the target track and position control for accurately following the head to the target track. In the speed control, an optimum moving speed curve up to the vicinity of the target track is set in advance, and the head is controlled to seek according to this speed curve. At this time, the head moving speed V continuously obtained as described above is determined. Used.

Further, since the sampling cycle is different for each zone, the position control for accurately following the head to the target track (here, it is set to zero based on the deviation information from the data track center obtained for each servo sector). (Sample value servo system with feedback loop)
Then, the characteristics of the servo system compensation filter realized as a digital filter by the μCPU 111 in FIG. 3 are adjusted so that the transfer characteristic becomes optimum for each zone. Generally, the sampling frequency is higher in the outer peripheral zone. When the sampling frequency is increased, the gain of the open-loop transfer characteristic of the servo system is increased. As a result, the servo band (gain cross frequency) is increased, the phase margin in the servo band is decreased, and the servo system becomes unstable. For this, the gain may be adjusted so that the servo band becomes constant, or the phase may be compensated so that the phase margin in the servo band becomes equal to or larger than a certain value.

[0067]

According to the present invention, since the disk medium can be designed so that the maximum linear recording density of data is substantially equal in all zones, the capacity improvement by using the ZBR method can be maximized. it can.

Further, in the disk medium of the present invention, there is no reduction in the number of servo sectors by using the ZBR method, and since the number of servo sectors can be increased in the outer peripheral zone, the head positioning performance becomes closer to the outer peripheral zone. There is an advantage that can be improved.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an arrangement of servo sectors and data sectors on a disk medium according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining the arrangement of servo sectors and data sectors in the zone boundary area in part A of FIG.

FIG. 3 is a block diagram showing the configuration of a disk device according to the embodiment.

FIG. 4 is a flowchart for explaining an outline of a servo sector detection procedure.

FIG. 5 is a flowchart for explaining a procedure for determining a next detection servo sector.

FIG. 6 is an explanatory diagram of a servo sector appearance time table created for a reference servo sector.

FIG. 7 is a diagram showing an example in which candidates for a next detection servo sector in adjacent zones are tabulated together with appearance times in advance.

FIG. 8 is a diagram showing an example of a head locus and servo sector detection timing for explaining a process of determining a next detection servo sector from the next detection servo sector candidates.

FIG. 9 is a diagram showing an arrangement of servo sectors and data sectors of a conventional disk medium.

[Explanation of symbols]

1 ... Disk medium 2, 10, 11, 12,
13 ... Servo sector 3 ... Data sector group 4 ... Reference servo sector 5 ... Zone boundary area 6, 7, 8, 9 ... Zone 14 ... Zone boundary 101 ... Disk medium 103 ... Head 118 ... Servo sector detection circuit

Claims (2)

[Claims] 1. All data tracks are divided into a plurality of zones each including a predetermined number of data tracks continuous in the disc radial direction, and the data recording / reproducing frequency is the same in one zone, but the data is recorded in different zones. In a disk medium having different reproduction frequencies and servo sectors having servo information for head positioning formed on the same surface as the data, a predetermined number of servo sectors are formed at equal angular positions at equal angular intervals in the same zone. At the same time, one or more data sectors are formed so as to be sandwiched between the servo sectors, a zone boundary area in which no data is recorded is provided between the adjacent zones, and the servo sector positions of the adjacent zones are set in the zone boundary areas. The first servo sector that overlaps at least partially in the track direction is a zone boundary area. The second servo sector which is formed to the center of the disk radial direction and which does not overlap is formed to extend from the zone having the second servo sector to the vicinity of the adjacent zones with the zone boundary area sandwiched therebetween. Medium. 2. All data tracks are divided into a plurality of zones each including a predetermined number of data tracks continuous in the disc radial direction, and the data recording / reproducing frequency is the same in one zone, but the data is recorded in different zones. In a disk device that uses a head to record and reproduce data using a disk medium that has different reproduction frequencies and that has servo sectors that have servo information for positioning the head, is formed on the same surface as the data, within a same zone. Servo sectors are formed at equal angular positions at equal angular intervals, and one or more data sectors are formed so as to be sandwiched between the servo sectors, and a zone boundary area in which no data is recorded is provided between adjacent zones. , Within the zone boundary area, the servo sector positions of adjacent zones are small in the track direction. The first servo sector which partially overlaps at least partially is formed up to the center of the zone boundary area in the disk radial direction, and the second servo sector which does not overlap is adjacent to the zone adjacent to the zone having the second servo sector across the zone boundary area. A disk medium formed to extend to the disk medium, means for decoding servo information read from the disk medium by the head and reproducing it as a servo signal, and the disk medium from the servo signal reproduced by this means Means for identifying the zone in which the head is present, means for identifying a servo sector in the zone identified by this means, and a servo sector to appear next following the servo sector detected by this means and to be detected next Means for extracting candidates and servo sectors to be detected next by this means Means for determining a next detection to Bekir servo sector from the accessory, the disk apparatus characterized by comprising a means for detecting the servo sector which is determined by this means.