JP2003068025A - Data recording disk and zone dividing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accelerate a data transfer speed in an inner zone and to increase recording capacity when dividing a data recording area into zones in an optical disk or magnetic disk. SOLUTION: The recording area for recording data is divided into a plurality of concentric zones in the direction of the radius, SNR when reproducing the data on the recording area are almost equal in all the zones, the width of the inner zone in the direction of the radius is greater than the width of an outer zone in the direction of the radius, and a unit data recording length in the inner zone is formed shorter than a unit data recording length in the outer zone.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data recording disk, and more particularly to a data recording disk in which a data recording area is radially divided into a plurality of zones and a zone dividing method thereof.

[0002]

2. Description of the Related Art In recent years, there has been a growing need to increase the capacity of data recording disks in order to store various types of information. In particular, there is a great need for storing moving images. In this case, it is desirable that the data recording disk has a high transfer speed and the inner and outer speeds of the disk are close to a constant speed.

FIG. 6 shows an example of a configuration block diagram of a conventional magneto-optical disk recording / reproducing apparatus which is normally used. The magneto-optical disk 1 is attached to a rotary shaft extended from a spindle motor 2, and one surface of the magneto-optical disk 1 is irradiated with a light beam 4 condensed by an objective lens 5 for storage / reproduction. A bias coil 8 is arranged on the opposite side of the disk 1, and a magnetic field required for recording is applied.

The optical system fixing section 7 includes optical system members such as a light source and a signal detecting section, and the light beam 4 emitted from this is an objective lens fixed to an actuator 6 on the VCM carriage 3. It is focused on the magneto-optical disk 1. The actuator 6 focuses the objective lens 5 so as to follow the surface deviation and eccentricity of the disk, and performs tracking with the actuator 6 and the VCM carriage. Seek the VCM carriage 3 to the disk 1
Move at high speed in the radial direction.

The recording / reproducing request signal is given from the personal computer 18 or the like through the interface 17. When this request signal is given to the drive controller 11, the number of tracks to be moved is calculated from the track to be recorded / reproduced and the current track position, and the servo controller 12 counts the number of traversing tracks while moving the VCM carriage 3 at high speed. Move and track to the target track.

When the disk controller 10 recognizes that the VCM carriage 3 is present in the track for recording / reproducing on the basis of the address information obtained from the signal detected from the reflected light from the magneto-optical disk, the disk controller 10 performs recording / reproducing. Data to be reproduced is encoded / decoded and recorded / reproduced via the LD driver 13 and the read amplifier 14.

The magnetic field during recording is the drive controller 1
1 is generated through the bias coil driver 9.
The spindle motor 2 is controlled by the drive control 11 via the spindle driver 16. Further, the actuator / VCM driver 15 receives the control signal from the servo controller 12 and controls the actuator 6 and the VCM carriage 3.

FIG. 7 shows an explanatory view of a division structure of a recording area of a conventionally used magneto-optical disk. As shown in FIG. 7, the conventional magneto-optical disk 1 is divided into a plurality of zones having a constant width in a radial concentric circle shape. Although only four zones (1 to 4) are shown in FIG.
Zones, 17 zones, 22 zones, etc. are standardized.

There is a system called a ZCAV format as a recording format of tracks in this zone. In this, although the innermost linear density of each zone is almost the same, the linear density of each zone increases toward the outer side. The recording method seems to be low. Here, the linear density is
It is the number of bits per fixed length. The low linear density means that the number of bits per fixed length is small and the length for recording one bit is long. Therefore, the "length for recording one bit" outside of a zone
Is longer than the inner "record length of 1 bit" in the same zone.

FIG. 8 shows a ZCAV of a conventional magneto-optical disk.
The explanatory view of 1 bit length in zone n with a format is shown. That is, it indicates that the length of 1 bit at the innermost circumference of the zone n is the shortest and gradually becomes longer toward the outer circumference, and the outermost circumference in the zone n is the longest.

FIG. 9 shows an explanatory diagram of the linear density of the conventional ZCAV format. According to this, the bit length per bit at the position of the innermost circumference of each zone is constant at amin, and becomes gradually longer as it goes to the outer circumference in that zone, and the bit at the outermost circumference in that zone becomes longer. Long amax
Indicates the longest.

In this ZCAV system, when recording / reproducing is performed by rotating the magneto-optical disk at a constant rotation speed,
Since the rotation speed is slow inside the disk, the data transfer speed is low, but outside the disk, the rotation speed is fast, so the data transfer speed is high. However, considering the inside of one zone, since the bit lengths of the inner circumference and the outer circumference are different, the data transfer rate is constant within one zone. FIG. 10 shows an explanatory diagram of the data transfer rate in this conventional ZCAV type magneto-optical disk.

A signal noise ratio (SNR) is used as a parameter indicating the signal quality of a reproduced signal reproduced from a disc. When the reproduced signal is S and the noise is N, the SNR is generally 20 log ₁₀ (S /
As indicated by N), the noise (N) generally increases as the transfer speed increases and the recording / reproducing frequency band widens, so the SNR decreases.

Therefore, since noise is large on the outer periphery of the disk having a high disk transfer rate, the SNR is small. On the other hand, since there is little noise inside the disk having a low transfer rate, the SNR becomes large. FIG. 11 shows an explanatory diagram of the SNR of a reproduced signal inside and outside of such a conventional magneto-optical disk.

If the design specifications require that the SNR is at least 18 dB, it is necessary to secure 18 dB at the outermost circumference of the disc. Assuming that the diameter of the disk is fixed,
From the requirement of SNR = 18 dB, the rotation speed of the disc and the maximum and minimum transfer rates of the disc are determined, and the performance of the disc recording / reproducing apparatus is determined.

FIG. 12 shows an example of parameter values such as the transfer speed of a conventional magneto-optical disk having a diameter of 120 mm when an SNR of 18 dB or more is required. This is an example of the case where the data recording area is divided into four zones, the track pitch is 0.6 μm, the number of tracks in each zone is 14167, the total number of tracks is 56668, and the number of rotations of the disk is 907 rpm. . The bit length means a length (μm / bit) for recording 1 bit in a track located at the innermost circumference in the zone. In this case, the total recording capacity of the magneto-optical disk is 6.96 GB.

According to FIG. 12, in the conventional magneto-optical disk, the widths of all four zones are the same (8.5 mm) and the bit lengths are all the same (0.235 μm / bit).
Is. Further, although the transfer speed is slow in the zone inside the disc, the SNR of the reproduction signal is 21.1 dB, which is higher than the required specification of 18 dB, and it can be said that there is a considerable margin.

[0018]

As described above, in the conventional magneto-optical disk, the data transfer rate of the inner zone of the disk is much slower than that of the outer zone, which is not preferable in the performance of the recording / reproducing apparatus. It was Regarding the SNR, it is preferable that the SNR margin is large in the zone inside the disc, but it is sufficient if at least the same level of SNR as the SNR in the zone outside the disc can be realized, and the SNR is unnecessarily large. Is not a big advantage.

At the present time, there is a strong demand for a larger capacity of the disk. At the same time, the transfer rate inside the disk is increased as much as possible to achieve high performance, and a linear density is satisfied while satisfying a certain SNR. It is desirable to increase the recording capacity to realize a high recording capacity.

Therefore, the present invention has been made in consideration of the above circumstances, and by increasing the zone width, the transfer rate of the zone inside the data recording disk is increased and the recording capacity is increased. It is an object of the present invention to provide a data recording disk which realizes a large capacity.

[0021]

According to the present invention, a recording area for recording data is divided into a plurality of concentric zones, and a radial width of an inner zone is larger than a radial width of an outer zone. (EN) A data recording disc characterized in that a unit data recording length of a large inner zone is formed smaller than a unit data recording length of an outer zone.

According to this, the data transfer rate of the zone inside the optical disk can be made faster than before,
The recording capacity of the data recording disk itself can be increased.

Further, the present invention is a zone division method for an optical disc in which a recording area for recording data is divided into a plurality of concentric zones, and a boundary between a kth zone and a k + 1th zone adjacent to each other. In order to maximize the total recording capacity of both zones when changing the radial position,
The present invention provides a zone division method for a data recording disk characterized by optimizing the radial width of each zone.

Here, the radial width of each zone corresponds to the number of tracks included in each zone, the radial width of the inner zone is larger than the radial width of the outer zone, and The optimization may be performed based on a setting condition such that the unit data recording length is smaller than the unit data recording length of the outer zone. By such optimization, it is possible to realize a higher data transfer speed in the zone inside the data recording disk and a higher recording capacity of the data recording disk than ever before.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below based on the embodiments shown in the drawings. The present invention is not limited to this. Although a magneto-optical disk will be described as an example in the following embodiments, a phase change optical disk, a ROM optical disk, and a magnetic disk can be applied to the zone structure.

FIG. 1 is an explanatory view of the zone structure of the magneto-optical disk of the present invention. Here, an example is shown in which the data recording area is divided into four zones 1 to 4. Assuming that the width of each zone in the radial direction is L1, L2, L3, L4 in order from the inner zone of the disc, the width L1 of the innermost zone 1 is the largest and the width L4 of the outermost zone 4 is the smallest. So that L1>L2>L3> L4.

Each zone is composed of a plurality of concentric tracks. The length (bit length or unit data recording) for recording 1 bit in the innermost track in each zone. (Length) is a1, a2, a3, a4 in order from the inner zone of the disc, the bit length a1 of the innermost zone 1 is the shortest, and the bit length a4 of the outermost zone 4 is the longest. Thus, that is, a1 <a2 <a3 <a4.

Here, the fact that the bit length of the zone of the minimum circumference is the shortest means that the linear density of the recorded data is the highest. Where the linear density D
Is defined as the reciprocal of the bit length a (D = 1 / a). Also,
D is the linear density of the innermost track in zone k (k = 1 to 4)
Let us denote it as k.

Further, as in the conventional case, the track pitch and the disc rotation speed are set so as to secure the SNR of 18 dB in the outermost zone having the worst SNR. Diameter 12
In the case of a 0 mm magneto-optical disk, the track pitch is Tp = 0.6 μm and the disk rotation speed is 907 r as in the conventional case.
pm.

Next, how to determine the zone width and the length for recording 1 bit in the innermost track in each zone will be described. Here, it is considered to optimize the number of tracks in each zone so that the data recording capacity of the entire disc is maximized. In the following description, the track pitch Tp = 0.6 μm and the inner diameter R ₁ = 24.0 mm of the innermost track of the innermost zone 1 of the disc are fixed values.

First, in order to increase the recording density in the inner zone of the disc, the linear density D _k of the inner zone is set to be shorter than that of the outer zone. This is because when the linear densities of the zones are the same as in the conventional case, the data transfer rate of the inner zone is slower, so that the data transfer rate of the inner zone is increased.

At this time, the bit length is set so that the SNR is secured at least 18 dB or more. For example, the bit length a ₄ of the outermost zone 4, the conventional same value as shown in FIG. 12 (0.235μm / bit), the order or less,
The bit length a ₃ of the zone ₃ is 0.224 μm / bit, the bit length a ₂ of the zone ₂ is 0.206 μm / bit, and the bit length a ₁ of the zone ₁ is 0.188 μm / bit.

Next, the principle of optimizing the number of tracks
explain. Now, the total number of tracks on the disc is a fixed value N = 5.
6668, and the number of tracks assigned to each zone
N_k(K = zone number, 1 to 4). Where N₁+
N ₂+ N₃+ N_Four= N. Optimized number of tracks
In order to maximize the recording capacity of the disc
For the purpose of optimization, but with the kth adjacent zone and k
Focus on the + 1st zone. kth zone and k + 1
When changing the recording capacity difference of the th zone,
The increase in the recording capacity of the eye zone and the k + 1th zone
To maximize the difference from the decrease in recording capacity,
The value of the number of tracks Nk is determined.

Since the track pitch Tp is a constant value (0.6 μm) in all zones, the number of tracks N _k and the width L _{k of} each zone have a one-to-one correspondence. That is, optimizing the number of tracks is equivalent to optimizing the width of each zone.

Generally, when the inner diameter of the _kth zone is R _k , the linear density is D _k , and the number of tracks is N _k , the recording capacity (the number of bits) of the _kth zone is 2πR _k · D _k · N _k. It is represented by. Further, it is represented by R _{k + 1} = R _k + T _p · N _k . At this time, the number of tracks in the k-th zone is increased by ΔN _k ,
Consider a case where the number of tracks in the (k + 1) th zone is reduced by ΔN _k . The recording capacity of the _kth zone increases by 2πR _k · D _k × ΔN _k due to the increase in the number of tracks.

On the other hand, the (k + 1) th zone is the number of tracks.
Is N_{k + 1}-ΔN_kAnd the innermost diameter of the zone is R
_{k + 1}+ TpΔN_kBecomes Therefore, the k + 1th zo
2πD_{k + 1}(R_{k + 1}N _{k + 1}−
(R_{k + 1}+ TpΔN_k) ・ (N_{k + 1}-ΔN_k).

Here, the difference between the increase in the recording capacity of the k-th zone and the decrease in the recording capacity of the k + 1-th zone, that is, the change in the recording capacity between adjacent zones is ΔS _k.
Then, ΔS _k = 2πR _k D _k ΔN _k −2πD _{k + 1} (R _{k + 1} N _{k + 1-} (R _{k + 1} + TpΔ
N _k ) (N _{k + 1} -ΔN _k )). The first term on the right side is the capacity increase in the kth zone, and the second term is the capacity decrease in the k + 1th zone.

When this equation is transformed using R _{k + 1} = R _k + TpN _k , ΔS _k = 2πΔN _k (R _k (D _k -D _{k + 1} ) -D _{k + 1} Tp (Nk-N _{k +1} + ΔN _k )) = -2πD _{k + 1} Tp (ΔN _k- (R _k (D _k -D _{k + 1} ) -D _{k + 1} Tp (N _k -N _{k + 1} )) / (2D _{k + 1} Tp)) ² + 2π (R _k (D _k −D _{k + 1} ) −D _{k + 1} Tp (N _k −N _{k + 1} )) ² / (4D _{k + 1} Tp).

This equation is a quadratic equation having a negative coefficient with respect to ΔN _k . The maximum of ΔS _k is given when ΔN _k = (R _k (D _k −D _{k + 1} ) −D _{k + 1} Tp (N _k −N _{k + 1} )) / (2D _{k + 1} Tp) However, ΔN _k = 0 should be _obtained when N _k and N _{k + 1} are optimal. Conversely speaking, the optimum number of tracks is N _k , N _{k + 1} where the above equation of ΔN _k is zero.

Therefore, in order to optimize the number of tracks so that the recording capacity becomes maximum, N _k -N _{k + 1} = R _k (D _k -D _{k + 1} ) / (D _{k + 1} Tp) It should be satisfied.

In order to specifically optimize the case of four zones, N _k (k = 1 to 4) satisfying the following four expressions should be obtained.

As described above, Tp and R ₁ are constant values, and the linear density D _k (k = 1 to 4) is a value determined so as to satisfy a predetermined SNR. Substituting into four equations, the number of tracks N in each zone is as follows:
_k (k = 1 to 4) is obtained. N ₁ = 20641, N ₂ = 16809, N ₃ = 11510, N ₄ = 7709

FIG. 2 shows parameter values of one embodiment of the magneto-optical disk of the present invention when the number of tracks is optimized. FIG. 4 is an explanatory diagram of the bit length for each zone of the magneto-optical disk of the present invention, and FIG. 5 is an explanatory diagram of the transfer rate for each zone. Here, the number N ₁ of tracks in the innermost zone ₁
Is the largest, and the zone width L1 (= 12.4) is also the largest. Moreover, since the inner diameter R _{1 of the} zone 1 is small, but the bit length a1 is also small, the transfer rate of the zone 1 is 12.1
It is Mbps, which is faster than the conventional one shown in FIG.

The SNR of the reproduction signal of zone 1 is 1
It is 8.3 dB, which is worse than before, but the SNR of the outermost zone required for the disc is 18.0 dB.
Since it is better than the above, there is no problem in the reproduction characteristics of data. The SNR of the zone 2, zone 3 and zone 4 has secured the required specification of 18.0 dB,
The transfer speed is also improved compared to the conventional one.

By optimizing the number of tracks according to the present invention,
Although the zone inner diameter R ₄ is slightly larger than that of the conventional disc shown in FIG. 12, the total recording capacity of the disc is 7.
It is 66 Gbytes, and it can be seen that a large capacity can be realized.

Further, as a reference example in FIG. 3, the width of each zone remains a constant value (= 8.5 mm), and the bit length of the innermost circumference in each zone is made different. Indicates the parameter value. According to this, since the bit length of the inner zone is shorter than the bit length of the outer zone, it can be seen that the transfer rate of the inner zone is faster than that of the conventional one in FIG.

[0047]

According to the present invention, the number of tracks for each zone of the data recording area, that is, the width of the zone is divided so that the inner zone is large and the outer zone is small. The data transfer rate of the inner zone can be increased while ensuring a predetermined SNR, and the total recording capacity of the disc can be increased.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a zone structure of a magneto-optical disk according to the present invention.

FIG. 2 is an explanatory diagram of parameter values of an embodiment of the magneto-optical disk of the present invention.

FIG. 3 is an explanatory diagram of parameter values of a reference example of the magneto-optical disk of the present invention.

FIG. 4 is an explanatory diagram of a bit length for each zone of the magneto-optical disk of the present invention.

FIG. 5 is an explanatory diagram of a transfer rate for each zone of the magneto-optical disk of the present invention.

FIG. 6 is a configuration block diagram of a conventional magneto-optical disk recording / reproducing apparatus.

FIG. 7 is an explanatory diagram of a divided structure of a recording area of a conventional magneto-optical disk.

FIG. 8 is an explanatory diagram of a ZCAV format of a conventional magneto-optical disk.

FIG. 9 is an explanatory diagram of the linear density of the ZCAV format of the conventional magneto-optical disk.

FIG. 10 is an explanatory diagram of a data transfer rate of a conventional ZCAV type magneto-optical disk.

FIG. 11 is an explanatory diagram of SNR of a reproduction signal of a conventional magneto-optical disk.

FIG. 12 is an explanatory diagram of parameter values of a conventional magneto-optical disk.

[Explanation of symbols]

L _k : Zone width a _k : Bit length R _k : Zone inner diameter N _k : Number of tracks

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Claims (3)

[Claims] 1. A recording area for recording data is divided into a plurality of concentric zones, a radial width of the inner zone is larger than a radial width of the outer zone, and a unit of the inner zone. A data recording disc, wherein a data recording length is formed smaller than a unit data recording length of an outer zone. 2. A zone division method for an optical disc in which a recording area for recording data is divided into a plurality of concentric zones, wherein a boundary radius position between the kth zone and the (k + 1) th zone adjacent to each other is changed. A zone division method for a data recording disk, characterized in that the radial width of each zone is optimized so that the total recording capacity of both zones is maximized. 3. The radial width of each zone corresponds to the number of tracks included in each zone, the radial width of the inner zone is larger than the radial width of the outer zone, and the inner unit 3. The zone division method for a data recording disk according to claim 2, wherein the optimization is performed based on a setting condition such that the data recording length is smaller than the unit data recording length of the outer zone.