JP2004071157A - Optical disk and optical disk device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent interference of a wobble signal from both side groups for the land track when a groove is wobbled to control the disk rotation and to generate a clock signal, in an optical disk of a land/groove recording system having a pre-format ID for each sector. <P>SOLUTION: This disk is an optical disk of a zone format in which a disk surface is divided into a plurality of zones by a radial position, in the optical disk of land/groove recording format in which the track of one rotation of the disk is constituted in sectors of the number of integer, wobble of the cycles of the prescribed integer is added to a groove in each sector. Wobble of each cycle is adjusted so as to be made the same phase between adjacent groups in each zone. Wobble of the cycles of the prescribed integer is divided into a plurality of unit wobble columns for each prescribed unit cycle, Binary information relating to a sector address is expressed by modulating a period of wobble in the unit wobble column. The frequency of wobble is set to so as to be a control frequency band of a tracking servo system or more and a frequency band of a data signal or less. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to an optical disc, and more particularly, to a track format and a sector format of an optical disc.

In an optical disc which manages recording and reproduction of data in units of sectors, a preformat ID method of preformatting identification information such as a track number and a sector number of the sector at the head of each sector, that is, a sector ID in the form of a prepit, etc. It is generally used for rewritable optical disks such as magneto-optical disks and phase change disks.
An advantage of the preformat ID method is that data can be easily managed in sector units. The data is divided into 512 bytes, 2048 bytes, or the length of a unit for recording and reproduction, and the data is written in the data area after the preformat area indicating the sector ID placed at the head of the sector. Since data of unit length follows the sector ID, access control can be easily performed.
As a technology for increasing the capacity of an optical disc, data is recorded in both a spiral guide groove (also called a groove) formed on the disc and a flat portion (also called a land) between the guide grooves. A so-called land / groove recording method is well known.

As a format of a large-capacity optical disk, a land / groove recording optical disk with a preformat ID that combines the two is under study.
As a specific example, FIG. 15 shows a conventional optical disk described in JP-A-6-176404, which is also called a land / groove shared address system. A land and a groove are used as data recording areas, and each sector is composed of an ID area obtained by preformatting a sector ID and a data area following the ID area.
Here, the groove track refers to a groove corresponding to one rotation of the disk starting from a predetermined radius line serving as a base point on the disk, and is composed of a continuous integer number of sectors. Similarly, the land track refers to a land corresponding to one rotation of the disk starting from a predetermined radius line serving as a base point on the disk, and is constituted by a continuous integer number of sectors. Similarly, a track referred to in the following text is a series of an integral number of sectors corresponding to one rotation of the disk, starting from a predetermined radius line serving as a base point on the disk.

In FIG. 15, data is recorded as recording marks on straight grooves and lands. The prepit ID indicating the sector ID is located near the center of the boundary between a pair of adjacent groove tracks and land tracks, and the two tracks share the same prepit ID. That is, the common pre-pit ID method is used.
This format has a great advantage that the recording capacity can be increased by making use of the features of land / groove recording, but it inherits the advantages and disadvantages of the preformat ID format. There is a need to overcome the shortcomings and provide a more usable optical disc format.

In the wobble groove ID method, which is another typical method of adding a sector ID, a so-called wobble is added, in which a groove is meandered by a small amount from a track center in a disk radial direction perpendicular to the track direction at a predetermined period. Further, there is a method of changing the meandering period by a method such as frequency modulation so as to express a sector ID or the like. This technology has already been put to practical use in CD-Rs, which are write-once compact disks (CDs), and mini disks (MDs), which are rewritable optical disks.
However, since the wobble groove meandering cycle is set to be much longer than the bit length of the data, the accuracy is low when it is desired to determine the position of the sector having the sector ID read from the wobble groove. If data is to be managed in sector units, it is necessary to provide a long buffer area between sectors, which is disadvantageous in increasing the capacity.

FIG. 16 shows a track format of a conventional groove-recorded optical disk with a wobble groove ID. This is an example of groove recording in which recording is performed only on a groove. In the figure, data is written on a groove track as a recording mark. The groove has wobbles, and the frequency of the wobbles is frequency-modulated to represent a track number or a sector number of a sector. Therefore, as shown in FIG. 16, the wobbles are Tw1, Tw2,. . . , Tw6 and the like.

Here, when applying the wobble / groove ID method to land / groove recording, it is possible to add a unique sector ID to the groove, but in the sector on the land, the grooves on both sides are Since the edges of the information of either groove are modulated and meandered by both the wobble of the upper groove and the wobble of the lower groove, the wobble grooves are both modulated and meandered. This can be understood from the fact that the ID signals are mixed and reproduced.
This drawback that land / groove recording is difficult to apply is a major obstacle in increasing the capacity of wobble / groove ID type optical disks.

On the other hand, the advantage of the wobble groove method is that since the groove meanders at a substantially constant period, the rotational speed of the disk can be detected by detecting the wobble period from a tracking error signal or the like. It is easy to control the disk to a desired rotational speed by utilizing the disk. Since this rotation speed is obtained from the disk surface itself for recording and reproducing data, it is more accurate than obtained from, for example, a disk rotation motor.
Further, by multiplying the frequency of the wobble signal thus obtained, a synchronization signal and a clock signal used for recording and reproducing data can be generated from information on the disk surface itself. As a result, there is no need to prepare a buffer area in the sector for absorbing an error between the clock of the optical disk device and the currently rotating disk speed, and the redundancy of the sector format can be reduced. The recording capacity can be increased by the amount of the buffer area. This is an advantage that the wobble groove method has regardless of whether or not the meandering period of the groove, that is, the frequency of the wobble signal is modulated.

Further, in the wobble groove ID method, the sector ID is arranged in a long area over the entire length of the sector so as to be superimposed on the data. Therefore, even if the disk surface is dirty or scratched, the entire sector ID information is stored. This has the advantage that the probability of crushing is low and the reliability of the disk under bad conditions is high.

In the preformat ID method, sector IDs are centrally arranged in a form separated from data. Since this sector ID is made as short as possible to reduce the redundancy of the sector format, if there is any dirt or scratches on the disk surface near the preformat ID, even if it is small, there is a probability that the entire sector ID information will be destroyed. high. At this time, even though the data recording area is usable, the sector becomes inaccessible. In a situation where a disk is used barely, such as a CD, the possibility that a large number of unusable sectors will occur in the disk increases.
In order to ensure the reliability of data by replacing such defective sectors, inspection of the entire surface of the disk, that is, certification is often performed during manufacturing. However, considering the cost of the disk, the cost of the inspection time for the certification, which takes a long time, is a factor that increases the disk price.
Alternatively, in order to ensure data reliability on a low-cost disk shipped without certification, it is necessary for the user to perform certification before starting use. Depending on the recording capacity, this usually takes tens of minutes to an hour or more, which is very inconvenient.

In a rewritable optical disk drive for driving a preformat ID optical disk, it is common to attach a rotary encoder or the like to a motor to detect the number of rotations of the disk in order to control the rotation of the disk. It is a factor and also a factor that hinders the thinning of the motor.
Here, even if an attempt is made to control the rotation of the disk by using the preformat ID that appears periodically, the rotation speed with a sufficiently high accuracy is usually achieved by using only a few to several tens of preformat IDs per rotation of the disk. It is difficult to control. Also, if some of the preformat IDs cannot be detected due to the dirt or scratches described above, the disk rotation becomes very unstable.

As described above, the preformat ID method and the wobble groove ID method have advantages and disadvantages contrary to each other. If the features of each of the two can be used in a complementary fashion, sector recording can be performed with high efficiency, and the reliability of accessing sectors even if the disk surface has dirt or scratches can be improved. An optical disk which is high and whose rotation can be easily controlled can be realized.

JP-A-6-176404

The conventional preformat ID optical disk is configured as described above, and thus has the following problems.
If there is dirt or scratches near the preformat ID, the entire sector ID information is destroyed, and the probability of occurrence of a sector that becomes inaccessible even though the data recording area is usable increases.
Further, in a situation where the disk is used naked, there is a high possibility that many unusable sectors will occur in the disk.

It is necessary to perform a full inspection for ensuring the reliability of the preformat ID at the time of manufacturing the disk, and the inspection cost is a factor that increases the disk price.
In order to ensure the data reliability of a disk without a full inspection, a long-time certification is required on the user side before starting to use, and this is very inconvenient.

If the rotation control of the disk is performed using only the preformat ID, it is difficult to control the rotation speed with sufficiently high accuracy.
When some of the preformat IDs cannot be detected due to dirt or scratches, the disk rotation becomes unstable.

Further, in a rewritable optical disk device that drives an optical disk of a preformat ID system, using a rotary encoder for rotation control of the disk increases costs.
This also hinders the thinning of the device.

(4) It is necessary to provide a buffer area in the sector for absorbing an error between the clock of the optical disk device and the rotating disk speed. For this reason, the sector format redundancy increases, and the recording capacity decreases by the amount of the buffer area.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has been proposed to complementarily introduce the features of the wobble groove ID system to an optical disk having a format of a preformat ID system, and to provide data in sector units. A large-capacity optical disk that is easy to manage, can efficiently perform sector recording, has high reliability in accessing sectors even if the disk surface has dirt or scratches, and has easy disk rotation speed control. The purpose is to:

At the same time, the objective is to reduce the cost of the optical disk and the optical disk device that drives the optical disk.

In the present invention, a zone format optical disk in which a disk surface is divided into a plurality of zones by a radial position, wherein a track making one rotation of the disk is composed of an integer number of sectors, and each sector has a preformat ID. In a land / groove recording format optical disk in which the preformat ID is radially aligned in each zone, a wobble of a predetermined integer number of cycles is added to the groove in each sector, and In this case, wobbles in each cycle between adjacent grooves are arranged to have the same phase. However, the wobbles do not necessarily have to have the same frequency.

In the second aspect of the present invention, in the optical disc, wobble of a predetermined integer cycle number added to a groove in each sector is further divided into a plurality of unit wobble columns for each predetermined unit cycle number. , The binary information including the sector address information is expressed. Further, the sector address information does not include the track number to which the sector belongs, and includes at least one of the zone number to which the sector belongs and the sector number indicating the arrangement order of the sectors in the track to which the sector belongs. To

In the third aspect of the present invention, in the optical disc, a value indicating a sector order when numbered sequentially from the end of the track is used as a sector number indicating a sequence of the sectors in a track to which each sector belongs. .

According to a fourth aspect of the present invention, in the optical disk device for driving the above-described optical disk, the rotational speed of the disk is controlled by utilizing the fact that the number of wobbles included in each sector is a predetermined integer number of cycles.

According to a fifth aspect of the present invention, in the optical disk drive for driving the optical disk described above, the data recording clock signal or the data reproduction clock is utilized by utilizing the fact that the wobble contained in each sector is a predetermined integer number of cycles. Generate a signal.

According to the sixth aspect of the present invention, in the optical disk device for driving the optical disk, when the preformat ID of the sector cannot be read, the access to the sector is performed based on the sector address information read from the wobble of the preceding sector. To do.

According to a seventh aspect of the present invention, in the optical disk drive for driving the above optical disk, the polarity of the tracking servo is set based on the sector address information read from the wobble in each sector.

In an optical disc according to an embodiment of the present invention, a preformat ID is added in a zone format such that sectors are aligned in a radial direction in a zone, and a land / groove recording format is used. A predetermined integer number of cycles of wobble is added to the groove of each groove, and in each zone, the wobble of each cycle is aligned so that it is in phase between adjacent grooves. Can be detected.

When binary information including sector address information is expressed by modulating and adding a predetermined integer number of wobbles to a groove in each sector of the optical disk, the sector address information includes a track number to which the sector belongs. And includes the zone number to which the sector belongs and the sector number indicating the arrangement order of the sectors in the track to which the sector belongs. At this time, the track number has a different value in the adjacent groove. However, the zone number to which the sector belongs and the sector number indicating the arrangement order of the sectors in the track to which the sector belongs have the same value in the adjacent groove. Receives the same wobble modulation, and can also read the same wobble signal from the wobble grooves on both sides and reproduce the same information even on lands sandwiched by wobbled grooves.
In this way, the wobble groove ID is added to the optical disk of the land / groove recording format.

Also, in the sector address information recorded in the wobble groove ID, a value indicating the sector order when numbered sequentially from the end of the track is displayed as a sector number indicating the arrangement order of the sectors in the track to which each sector belongs. Therefore, in the land / groove recording optical disk of the single spiral format, the value indicating the sector order is used to detect the timing of the connection point between the land track and the groove track, which is essential for switching the tracking polarity. .

The detected wobble signal has a predetermined integer cycle number of wobbles included in each sector. By using this, an error in the disk rotation speed is detected, and the disk rotation speed is controlled.

Since the wobble contained in each sector has a predetermined integer number of cycles, the frequency of the wobble signal is multiplied to generate a data recording clock signal or a data reproduction clock signal.

(4) When the preformat ID of a sector cannot be read, the current zone is determined and the sector is accessed based on the sector address information read from the wobble of the preceding sector.

When the preformat ID of the sector cannot be read, the polarity of the tracking servo is set based on the sector address information read from the wobble in each sector.

Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.
Embodiment 1 FIG.
FIG. 1 shows an improved land / groove recording optical disk with a preformat ID described in the conventional example according to the present invention. This land / groove shared address method will be described as a specific example. The land and the groove are used as data recording areas, and each sector is the same in that an ID area obtained by pre-formatting a sector ID and a data area following the ID area are the same.

In FIG. 1, data is recorded as a recording mark on a groove wobbled and a land between the groove. The pre-pit ID indicating the sector ID is arranged near the center of the boundary between a pair of adjacent groove tracks and land tracks, and both tracks share the same pre-pit ID. The method of adding the pre-pit ID is not limited to this, but the present invention has a gist regarding the method of adding the wobble of the groove, so that the following description will be made based on this conventional example.

The groove wobbles always meander in the same direction by the same amount between sectors adjacent in the disk radial direction. Therefore, the wobble period of the groove may be changed on the sector or may be constant. However, the wobble period is set to be the same period and the same phase as the adjacent groove. FIG. 1 illustrates a wobble cycle of a certain cycle.

FIG. 2 shows another example of a land / groove recording optical disk with a preformat ID according to the present invention. As in FIG. 1, the wobble of the groove always meanders by the same amount in the same direction between sectors adjacent in the disk radial direction. However, this is an example in which the wobble cycle of the groove is changed on the sector. The point that the adjacent groove is set to have the same cycle and the same phase remains unchanged. The wobble signal can be read in the land sector between the grooves, while the wobble cycle in each cycle is different and the sector address information and the like can be expressed.

FIG. 3 shows how a wobble signal is detected when the optical disk of FIG. 1 is driven. In FIG. 3, the wobble signal has a constant frequency in the sector, and a signal during reproduction of the sector of the groove track is shown. At this time, the center of the track is the center of the groove, and a signal indicating a positional deviation in the disk radial direction between the track center and the light spot for reproducing the disk is a radial direction difference signal. In the ID area, the preformatted pits are shifted downward as shown in FIG. At this time, it is assumed that the polarity of the radial direction difference signal becomes negative. Then, the wobble of the groove also appears in the radial direction difference signal with the meandering in the radial direction having a positive polarity at the upper side in the figure and a negative polarity at the lower side.

In the example of FIG. 3, it is set so that a wobble of 2 cycles is added to the ID area, a wobble of 16 cycles is added to the data area, and a wobble of 18 cycles is added to the entire sector. Usually, the wobble amplitude, which is the width of the groove meandering, is set to a very small amount with respect to the track pitch so as not to affect the data recording / reproducing characteristics. For example, in the above-described CD-R, the wobble amplitude is about 0.03 μm for a track pitch of 1.6 μm. The amplitude of the wobble in the present invention is set to a very small amount that is substantially the same.
On the other hand, the center of the preformat ID pit in the ID area is displaced in the radial direction by half the track pitch from the track center. Therefore, the wobble amplitude is a small amount as compared with the amplitude of the radial direction difference signal in the ID area. In FIG. 3, the wobble waveform is shown by a thin line in order to clearly indicate the number of cycles of the wobble in the ID area. However, this part is actually a signal of negative polarity due to the ID pit. At the time of manufacturing the disc, the ID pits in this portion may be meandering in the radial direction and preformat-recorded as in the case of the groove, or the ID pits in this portion may be arranged straight. In any case, the wobble signal cannot be detected from the radial direction difference signal in the ID area.

The wobble signal detected in the data area is reproduced through a band-pass filter and an amplifier for amplifying only the wobble signal band, and is further binarized by a binarization circuit to obtain a binarized wobble signal. When the rising edge of the binarized wobble signal is extracted, a signal indicating the rotation of the disk is obtained. To be more precise, it indicates the relative moving speed at which the light spot for recording and reproducing the disk scans the disk surface, that is, the linear velocity of the disk. This is shown in the wobble edge signal in FIG. When the wobble is inscribed on the disk at a constant frequency, the wobble edge signal appears at a constant period. Therefore, the rotation motor of the disk is controlled so that this period has a desired disk linear velocity. Note that a falling edge may be extracted from the binarized wobble signal, and a similar edge signal can be obtained.

In the conventional preformat ID type disk having no wobble in the groove, the disk linear velocity can be detected only when the appearance period of the ID pit is the minimum interval. If a wobble is added to the groove, in this example, detection can be performed at a period of 1/18 of the appearance period of the ID pit. Since this can be directly reflected on the reduction of the error in the control of the rotational speed of the disk, the rotational speed of the disk can be controlled more accurately.
Further, the ID area is set to be much shorter than the data area on the disk. This is because the ID area is a redundant portion which does not originally contribute to the data recording capacity, and is therefore made as short as possible in the disc format design. Therefore, the ID area is relatively weak against dirt and scratches on the disk. When ID pits cannot be detected due to dirt or scratches, if the disk rotation speed is controlled only by the ID pits, there is a high possibility that the disk rotation becomes unstable. Groove wobbles can be detected on the entire surface of the disk other than the ID area, and the number of them is large. Therefore, if the groove wobbles are used for controlling the disk rotation speed as a measure against dirt or scratches on the disk, the durability is greatly enhanced, and the reliability is improved. improves.
In a typical rewritable optical disk device, it is common to add a rotary encoder to a disk motor for detecting the rotation speed of the disk in consideration of such rotation speed control accuracy and reliability, but it is necessary to add a wobble to a groove. This eliminates the need for this rotary encoder.

Here, the limiting condition for the wobble frequency will be qualitatively described. The lower frequency limit is defined by the tracking control band. If the wobble period is too long, the tracking servo system causes the light spot to follow the wobble, which makes it difficult to detect a wobble signal and causes an extra disturbance element to the tracking control system. It is desirable that the wobble frequency is set to a frequency which is about 10 times or more of the band of the tracking control system. Generally, the band of the tracking control system is about 10 to 20 kHz, so that the setting of the wobble frequency is about 150 kHz or more.
The limit on the high frequency side is defined by the band of the data signal. The wobble signal is very small and needs to be amplified and detected. In order to prevent the data signal from being mixed into the wobble signal as large noise, it is desirable that only the wobble signal can be extracted and amplified by the bandpass filter. Therefore, it is desirable that the frequency can be set so as to be separated from the spectrum on the lower frequency side of the data signal. Generally, the band of the data signal has a peak at about 1 MHz to several MHz, and if the setting of the wobble frequency is considered to be about 1/10, the frequency of the data signal is about 100 kHz or less.

Further, generation of a recording / reproducing clock signal using a wobble signal will be described. As practiced in a sample servo type optical disk, it has been realized to generate a clock signal for recording and reproducing data by using periodic synchronization information embedded on the disk surface. For example, in the sector format using the 4/15 recording code in ISO / IEC-9171, the detection period of the synchronization information was 300 times the period of the data channel clock frequency. A wobble signal detected from the disk surface is multiplied by 300 by a phase synchronization circuit to generate a recording / reproducing clock signal.
If the wobble frequency can be set to about several hundredths of the channel clock frequency or more, synchronization information can be obtained from the disk surface, and accurate clock generation and synchronization management can be realized. Actually, if the frequency of the wobble falls within the range defined by the band of the tracking control system and the band of the data signal, the condition that the channel clock signal can be generated from the synchronization information on the disk surface is satisfied.

In a conventional rewritable optical disk device such as a magneto-optical system, a crystal oscillator having a precise frequency is prepared for a channel clock to generate a clock signal, while the rotation control of the disk is not accurate as described above. When required, a precise and expensive rotary encoder is used to ensure synchronization between the disk rotation and the data channel frequency. If the disk rotation is too fast relative to the data channel clock, the end of the sector will extend when recording, and will bite into the next sector. In order to prevent this, a method has been adopted in which a margin area serving as a buffer is defined on a sector of a disk, and the error is managed so that the margin area is within an allowable range.

As described above, it has been found that if the wobble frequency is the same in all sectors, unprecedented advantages can be exhibited in controlling the disk rotation and generating a clock signal for recording and reproduction. However, it is impossible to express sector address information, which is another feature of the wobble groove ID system, as it is.
In the wobble groove ID method, a wobble cycle, that is, a wobble frequency is modulated to express sector address information. In the present invention, since there is a restriction condition that the wobble has the same phase as that of the adjacent groove as described above, the following is considered in determining the modulation method of the wobble frequency.

First, there is a method in which the wobble frequency is set to the same constant frequency between sectors adjacent in the same disk radial direction and is made different between sectors in the circumferential direction. In such a case, in each sector within one track, The number of wobble cycles in one sector is different. Assuming that one sector has the same length, this method has a defect that the wobble cycle cannot be used for controlling the disk rotation speed, and is unacceptable.
Therefore, in the present invention, in a zone format optical disk, wobble modulation is performed using only the same sector address information among sectors arranged in the disk radial direction among sectors included in each zone. . It is the zone number to which these sectors belong and the order of the sectors in the track to which those sectors belong. Since the track number always differs between adjacent grooves, it cannot be included.
Since a track is a series of an integral number of sectors corresponding to one rotation of the disk starting from a predetermined radius line serving as a base point on the disk, if the adjacent sectors are in the same zone, the order of arrangement of the sectors in the track is assumed. Is the same. The arrangement order of the sectors will be referred to as a sector number. To avoid misunderstanding, the sector number is partial information included in the sector address information together with the zone number and the track number.

If different sector numbers are given to all the sectors in one track, the track number cannot be identified but the sector number can be identified by the wobble ID. In the state of continuous tracking, the same track number is read from each sector without changing the track number during one rotation. Even if the reading of the preformat ID fails, the estimation can be performed with a high probability. If the sector number is known from the wobble ID in this way, access to the sector can be executed without any problem unless reading of the preformat ID has failed for one track in succession. Originally, on the premise that the complete sector ID is read from the pre-format ID, the wobble ID is intended to be used as a supplementary means. Therefore, it can be said that the function is sufficient if it has such a function.
At this time, even in the land track sector on the land / groove recording optical disk, the modulated grooves on both sides meander in the same phase, so that the wobble waveform is accurately read and the sector address information is read. Now it is possible to play. Thus, the wobble groove ID can be added to the land / groove recording format optical disk.

Embodiment 2 FIG.
Next, the wobble signal waveform will be described. FIG. 4 shows a specific example of the correspondence between binary information expressing sector address information and a wobble signal waveform. The binarized information represented by the wobble modulated as described above will be referred to as wobble information bits. Here, one wobble information bit is represented by an eight-cycle wobble signal waveform. For example, "0" is represented by a low-frequency (frequency: fL) LF waveform 4 cycles followed by a high-frequency (frequency: fH) HF waveform by 4 cycles, and "1" is represented by a high-frequency (frequency: fH). After the HF waveform of 4 cycles, the LF waveform of the low frequency (frequency: fL) is represented by a waveform that continues for 4 cycles. In this case, the length of one wobble information bit becomes constant regardless of the information.
Also, the wobble waveform carved on the disk surface is substantially sinusoidal. This is because in a mastering apparatus for a disk, it was considered that the disk could be manufactured even if the response band of the deflection system for deflecting the cutting beam was not so high.

As another example, FIG. 10 shows a wobble waveform carved on the disk surface in a substantially rectangular waveform. This requires a somewhat high response band in the deflection system that deflects the cutting beam in a disk mastering device, but a device that can cut ID pits of the shared address method can produce enough wobbles of this size. It is.

When this frequency modulation method is applied to the example shown in FIG. 3, the actually modulated wobble signal waveform is as shown in FIG. In the example of FIG. 5, as in FIG. 3, a 2-cycle wobble is added to the ID area, a 16-cycle wobble is added to the data area, and a 18-cycle wobble is added to the entire sector. The wobbles in the ID area were not modulated.
In this example, the interval between the wobble edge signals changes every four cycles, and the interval between the edge signals is significantly different from the predetermined interval, which is a wobble period at the time of non-modulation. However, this is merely an example for conceptual explanation. When applied to an actual optical disk format, the interval between edge signals can be set so as to hardly affect the accuracy of disk rotation control or the accuracy of a generated clock signal. Examples of the numerical values will be described later.

FIG. 6A shows an example of the format of sector address information represented by wobble information bits. The meaning of each field is as follows. SYNC is a synchronization signal for capturing a reading start point of sector address information, ZoneNo. Is the zone number, SectorNo. Is a sector number, and EDC is an error detection code for checking whether there is an error in the reproduction result of the sector address information.
FIG. 6B shows an example of the length of wobble information bits allocated to each field. SYNC, ZoneNo. , SectorNo. 8 bits and 16 bits for EDC, respectively, and consider a case where 40 bits are used in total per sector. At this time, the zone can be expressed up to 127 zones, and the number of sectors per track can be expressed up to 127 sectors, and the probability of overlooking erroneous detection can be reduced to 1/65000 or less. The number of wobble information bits that can be actually set is limited and determined by the format of the data sector and the wobble cycle.

7 and 8 show an example of a method of setting a sector number. As an example, a zone-formatted disk composed of 9 zones and given zone numbers 0, 1,..., 8 in order from the inner zone is shown. In the innermost zone 0, one track has 8 sectors, and in the outermost zone, the number of sectors increases one by one. In the outermost zone 8, one track has 16 sectors.
In FIG. 7, the sector numbers as the order of the sectors included in the sector address information are assigned as 0, 1, 2,... The feature is that each track always starts from sector number 0.
In FIG. 8, conversely, the sector numbers as the order of the sectors to be included in the sector address information are assigned as 0, 1, 2,... In order from the end of the track. The feature is that each track always ends with sector number 0. This makes it possible to easily detect the end timing of each track regardless of the zone, so that it becomes very easy to use the sector number in a track format requiring servo processing at a track boundary. Next, an example thereof will be described.
Although not shown, there is also a method of numbering sector numbers, starting from 1 and going to 2, 3,. As a result, "0" can be used for a special purpose such as a synchronization signal, and can be used for improving the accuracy of error detection. This is applicable to both examples shown in FIGS.

FIG. 9 shows a track format of the land / groove recording type optical disk. (A) is known as a general land / groove recording method, in which groove tracks are provided spirally on a disk. Therefore, there are two spirals on the disc, a spiral consisting of a groove track and a spiral consisting of a land track, and is called double spiral-land / groove (DS-L / G) recording. In this case, if the tracking polarity is set to the groove side when tracking is performed, the light spot continues to follow the groove track without causing tracking deviation. Conversely, if the tracking polarity is set to the land side, the track continues to follow the land track.

Therefore, no special consideration is required for switching the tracking polarity as in the case of the conventional mere groove recording or mere land recording optical disks. It was sufficient to switch when a track jump between land and groove was necessary.

FIG. 9B shows a format in which a groove track and a land track are alternately connected for each rotation of the disk to form a single spiral formed by connecting the groove track and the land track on the disk. This is a format called land / groove (SS-L / G) recording. In SS-L / G, in order to continue tracking continuously, it is necessary to correctly detect a connection point between a land track and a groove track and to switch the tracking polarity every one rotation of the disk. Even if the preformat ID cannot be detected, the switching timing must be detected.
If the sector numbering method shown in FIG. 8 is used, not only the connection point between the land track and the groove track can be read from the sector number recorded in the wobble groove ID, but also the sector number can be read. By simply issuing the command, it is possible to immediately know whether or not the vehicle is at a connection point or how close the vehicle is to the connection point, without any arithmetic processing, regardless of the current zone.

Embodiment 3 FIG.
Hereinafter, a specific example will be described in which the present invention is applied to an actual optical disk format.
FIG. 14 shows a format of a data sector to which the wobble groove according to the present invention is applied. (A) shows the allocation of the number of information bytes, (b) shows the allocation of channel bits, (c) shows the allocation of wobbles, and (d) shows the allocation of wobble information bits.
It is assumed that the sector length is 2697 bytes, 128 bytes are allocated to the ID area and 2569 bytes are allocated to the data area, and can accommodate 2048 bytes of user data. The above information bytes are recorded and encoded using a recording code for converting one byte into 16 channel bits. For example, it is conceivable to use an 8/16 modulation code or a (2,7) modulation code.
At this time, the ID area has 2048 channel bits (ch.bit), the data area has 41104 channel bits, and the entire sector has 43152 channel bits. Next, wobble modulation in which wobbles of one cycle (Cyc) are applied to 186 channel bits is applied and quantized and divided so that the number of wobbles is a multiple of 8, so that 16 cycles are allocated to the ID area and 216 are allocated to the data area. 232 cycles of wobble can be added to the entire cycle and sector.

The reason why the wobble cycle is set to 186 channel bits is that the entire sector had to be a multiple of 8 wobble cycles in order to apply the wobble modulation method shown in FIG. As described above, the wobble frequency is restricted by the control band of the tracking servo system and the frequency band of the data signal, and it is necessary to satisfy the conditions.
Assuming that the channel clock frequency is about 30 MHz, the longest inversion interval by recording encoding is 10 times the channel clock, and NRZI recording is performed, the lowest signal frequency of the data system is 1.5 MHz. If the wobble frequency is to be reduced to 1/10 or less of the minimum signal frequency of 1.5 MHz, the condition of the wobble frequency is 150 kHz or less. On the other hand, since 150 kHz or more is required as a constraint condition from the tracking servo system, the wobble frequency is not other than around 150 kHz.
Further, since the channel bit length 43152 of the sector can be factored into 3 × 31 × 29 × 16, if the whole sector is set to a wobble cycle number that is a multiple of 8, the remainder is (wobble period) × (wobble information bit Number) = 2 × 3 × 31 × 29. Here, 186 = 2 × 3 × 31 channel bits are set as a wobble period, and the number of wobble information bits is set at 29 bits. Hereinafter, this example will be described. As can be understood from the present calculation, the 174 = 2 × 3 × 29 channel bits may be used as the wobble period and the number of wobble information bits may be set as 31 bits.

When the wobble cycle is 186 channel bits, if the channel clock frequency is 30 MHz, the wobble frequency is about 161 kHz, which just applies to the above-mentioned constraint of about 150 kHz. When the wobble cycle is 174 channel bits, the wobble frequency is about 172 kHz.
In this way, wobbles of 232 cycles can represent 29 bits of wobble information. However, since the ID area is practically unusable, it is omitted, and the last bit of the sector is reserved as a buffer. The information bit number is 26 bits from 3 to 28.

FIG. 11 shows an example of wobble information bit allocation taking into account this range. The role of the information bit field is the same as that shown in FIG. In each of the specific examples, SYNC is 8 bits and EDC is 6 bits. Specific example-A shows a case where the zone numbers from 0 to 23 and the sector numbers up to 40 are required as information to be expressed. At this time, ZoneNo. 5 bits, SectorNo. Requires 6 bits, for a total of 25 bits.
In the specific example-B and the specific example-C, the remaining one bit is set to ZoneNo. , And SectorNo. Shows the case where it is attached to. It is better to select the one that has enough capacity in consideration of the scalability to increase the capacity in the future. If emphasis is placed on improving the linear recording density, a specific example -C is obtained.

FIG. 12 shows an example in which the wobble information bits thus selected are arranged in a sector. (A) shows the above-mentioned specific example-B. In (b), the resolution for expressing the zone is coarsened, and this is used for expanding the sector number and improving the error detection capability. In (c), the zone number is omitted, and the error detection capability is further improved. In (d), a wobble called Clock is provided before the SYNC, but the wobble period is set to 186 channel bits per cycle, and is left as a portion not subjected to frequency modulation. Since the interval between the wobble edge signals is constant, it is possible to facilitate and stabilize the circuit design in the process of controlling the disk rotation speed and generating the clock signal. It aims at system stability rather than the amount of information content to be expressed.

Here, the processing of the wobble signal when the recording capacity is expanded or the disk rotation speed increases in the future will be described. When the recording capacity increases due to the improvement of the linear recording density, the channel clock frequency of the data system increases while the number of rotations of the disk remains the same. However, if there is no change in the logical format of the sector, that is, the assignment of data bits and wobble bits, the length of the wobble cycle measured by distance is shortened by an increase in the linear recording density, so that the wobble frequency also increases. The relationship of the ratio with the channel clock frequency does not change.
Further, when the disk rotation speed increases in proportion to the improvement in the linear recording density, the control band of the tracking servo system increases, so that the relationship between the ratio and the wobble frequency does not change. When the disk rotation speed increases with the same linear recording density, the margin tends to decrease because the control band of the tracking servo system approaches the wobble frequency. However, under the above conditions, a margin of about 10 times is provided, so that it is within a range that does not cause a problem unless the disk rotation speed is significantly increased.

FIG. 13 is a diagram illustrating restrictions on the modulation factor when frequency-modulating a wobble signal. The wobble waveform before frequency modulation was a CF waveform (frequency: fC). The four cycles of the CF waveform have a length corresponding to exactly half of the wobble information bit.
The state shown in the LF waveform (frequency: fL) is the waveform having the longest period allowed for the wobble signal. The maximum allowable period Tc. The length of four cycles of max must be less than 4.5 cycles of the CF waveform. This is because when the detected wobble edge signal is processed as a phase error signal in the frequency synchronization circuit of the disk rotation speed control circuit or the clock signal generation circuit, the wobble edge signal falls within the detection window width of the phase error, that is, enters the phase lock range. Is a prerequisite for
The state shown in the HF waveform (frequency: fH) is the shortest period waveform allowed for the wobble signal. The shortest allowable period Tc. The length of four cycles of min must be 3.5 cycles or more of the CF waveform. This is Tc. Similar to max, this is a necessary condition for the detected wobble edge signal to fall within the phase lock range.

As a numerical example, in the above case where the wobble period is 186 channel bits, Tc. max is equal to or less than 208 channel bits, and Tc. min needs to be 164 channel bits or more.
For example, Tc. max is 200 channel bits, Tc. Assuming that min is 172 channel bits, the frequency modulation degrees of the LF waveform and the HF waveform with respect to the CF waveform are both 7.5%. At this time, since the frequency difference between the LF waveform and the HF waveform is about 15%, it is possible to sufficiently detect the frequency modulation waveform.

In the optical disk of the present invention, the rotation of the disk can be controlled using the wobble of the groove, which is much more frequent than the preformat ID, so that it is possible to perform the rotation speed control with sufficiently high precision.
Further, even when some of the preformat IDs cannot be detected due to dirt or scratches, the disk rotation can be stabilized.
Further, in a rewritable optical disk drive for driving an optical disk of the preformat ID system, a rotary encoder used for controlling the rotation of a normal disk can be eliminated, and the cost can be reduced.
At the same time, the rotary encoder has been removed and the disk motor can be made thinner, and the device can be made thinner.
Also, in an optical disk, a buffer area provided in a sector for absorbing an error between a speed of a rotating disk and a clock of a driven optical disk apparatus can be reduced, and data can be recorded by the omitted buffer area. It became possible to increase the capacity.

According to the second aspect of the present invention, in a land / groove recording optical disk having a zone format having a preformat ID in each sector, the wobble is modulated so that the groove of each sector has the same phase in each cycle between adjacent grooves. This makes it possible to add sector ID information by using a wobble groove.
By utilizing this and duplicating and recording the sector ID in the preformat ID and the wobble groove ID, the reliability of the disk can be greatly improved.
Even if the entire sector ID information is crushed due to dirt or scratches near the preformat ID, the sector address information can be reproduced from the modulated wobble, thereby greatly reducing the probability of occurrence of an inaccessible sector. I was able to.
As a result, if the data recording area is usable, recording and reproduction on the sector can be performed, and the reliability of the disk can be greatly improved.
In particular, it is possible to greatly reduce the possibility of generating unusable sectors in a disk under bad conditions such as when the disk is used naked.
Further, it is possible to omit the entire inspection performed for ensuring the reliability of the preformat ID at the time of manufacturing the disk, and it is possible to reduce the inspection cost, which is a main factor of the disk price, and to greatly reduce the disk size. The price can be reduced.
It is also possible to ensure data reliability with discs without full inspection, eliminating the need for long-term certification on the part of the user before starting use, making it possible to use optical discs very conveniently. .

In the optical disc according to the third aspect of the present invention, detection of the switching timing of the tracking polarity at the connection point between the land track and the groove track, which is indispensable for a single spiral format land / groove recording optical disc having a preformat ID in each sector. Can be read out in duplicate from the sector ID information recorded in the preformat ID and the wobble groove ID, and the reliability of the tracking servo can be greatly improved.
This makes it possible to detect the connection point between the land track and the groove track from the modulated wobble even when the entire sector ID information is crushed due to dirt or scratches near the preformat ID, and the tracking error is reduced. The probability of occurrence could be greatly reduced.
As a result, it is possible to reduce the probability of occurrence of a failure that causes a tracking error during continuous recording and causes data recording failure or destruction of recorded data, and significantly improves the reliability of data and devices. .

In the optical disk device of the fourth aspect of the present invention, the rotation of the disk can be controlled using the wobble of the groove, which is much more frequent than the preformat ID, so that the rotation speed control with sufficiently high precision can be performed. Was.
Further, even when some of the preformat IDs cannot be detected due to dirt or scratches, the disk rotation can be stabilized.
Further, in a rewritable optical disk drive for driving an optical disk of the preformat ID system, a rotary encoder used for controlling the rotation of a normal disk can be eliminated, and the cost can be reduced.
At the same time, the rotary encoder has been removed and the disk motor can be made thinner, and the device can be made thinner.

In the optical disk device of the fifth aspect of the present invention, it is possible to generate a clock signal for recording or reproduction in synchronization with synchronization information directly obtained from a rotating optical disk surface. The buffer area provided in the sector to absorb the error between the state and the clock of the driving optical disc device can be reduced, and the data recording capacity can be increased by the omitted buffer area. became.
Further, it is possible to avoid overwriting the sector during recording due to an error between the rotation state of the disk and the clock of the optical disk device to be driven, thereby causing data destruction.
In this way, the reliability of the optical disk device can be greatly improved.

In the optical disc device according to the sixth aspect of the present invention, it is possible to read the sector ID from both the preformat ID and the wobble groove ID recorded in duplicate.
By utilizing this, even when the entire sector ID information is crushed due to dirt or scratches near the preformat ID, it becomes possible to reproduce the sector address information from the modulated wobble, and to make the sector inaccessible The probability of occurrence could be greatly reduced.
As a result, if the data recording area is usable, recording and reproduction on the sector can be performed, and the reliability of the disk can be greatly improved.
In particular, it is possible to greatly reduce the possibility of generating unusable sectors in a disk under bad conditions such as when the disk is used naked.
Further, it is possible to omit the entire inspection performed for ensuring the reliability of the preformat ID at the time of manufacturing the disk, and it is possible to reduce the inspection cost, which is a main factor of the disk price, and to greatly reduce the disk size. The price can be reduced.
It is also possible to ensure data reliability with discs without full inspection, eliminating the need for long-term certification on the part of the user before starting use, making it possible to use optical discs very conveniently. .

In the optical disc apparatus of the seventh aspect of the present invention, the switching timing of the tracking polarity at the connection point between the land track and the groove track, which is indispensable for a single spiral format land / groove recording optical disc having a preformat ID in each sector. Detection can be duplicated and read from the sector ID information recorded in the preformat ID and the wobble groove ID, and the reliability of the tracking servo can be greatly improved.
This makes it possible to detect the connection point between the land track and the groove track from the modulated wobble even when the entire sector ID information is crushed due to dirt or scratches near the preformat ID, and the tracking error is reduced. The probability of occurrence could be greatly reduced.
As a result, it is possible to reduce the probability of occurrence of a failure that causes a tracking error during continuous recording and causes data recording failure or destruction of recorded data, and significantly improves the reliability of data and devices. .

According to the invention as described above, the features of the wobble groove ID method are complementarily introduced into the optical disk having the format of the preformat ID method to solve the problem of the format of the preformat ID method, and the surface of the disk becomes dirty. High reliability to access sectors even if there is a scratch or damage, easy control of disk rotation speed, and the ease of data management in sector units and the efficiency of sector recording, which are the features of the preformat ID method. A large-capacity optical disk and a driving device for the same can be realized at a low cost.

Although the above description has been made based on the so-called common pre-pit ID method, the gist of the present invention relates to the addition of wobble to a groove in general land / groove recording optical disks of the pre-format ID method. Therefore, the range to which the present invention can be applied is not limited to the example described in the embodiment, and it goes without saying that the present invention can be generally applied even if the form of the preformat ID is different from the above.

FIG. 2 is a diagram showing a track layout of the optical disc according to the first embodiment of the present invention. FIG. 2 is a diagram showing a track layout of the optical disc according to the first embodiment of the present invention. FIG. 3 is a diagram showing a wobble signal of the optical disc according to the first embodiment of the present invention. FIG. 6 is a diagram for explaining a modulation method of a wobble signal of the optical disc according to the second embodiment of the present invention. FIG. 8 is a diagram showing a modulated wobble signal of the optical disc according to the second embodiment of the present invention. FIG. 8 is a diagram showing a format of wobble information of the optical disc according to the second embodiment of the present invention. FIG. 9 is a diagram showing sector numbers of an optical disc according to Embodiment 2 of the present invention. FIG. 9 is a diagram showing sector numbers of an optical disc according to Embodiment 2 of the present invention. FIG. 7 is a diagram showing a track layout of the optical disc according to the second embodiment of the present invention. FIG. 6 is a diagram for explaining a modulation method of a wobble signal of the optical disc according to the second embodiment of the present invention. FIG. 9 is a diagram showing a format of wobble information of an optical disc according to Embodiment 3 of the present invention. FIG. 9 is a diagram showing a sector format of the optical disc according to the third embodiment of the present invention. FIG. 9 is a diagram illustrating a modulation method of a wobble signal of an optical disc according to a third embodiment of the present invention. FIG. 9 is a diagram showing a sector format of the optical disc according to the third embodiment of the present invention. FIG. 11 is a diagram showing a track layout in a conventional land / groove recording method. FIG. 10 is a diagram illustrating a method of adding a wobble ID in a conventional wobble groove recording method.

Claims (2)

An optical disk of a zone format, in which a disk surface is divided into a plurality of zones by a radial position, wherein an optical disk of a land / groove recording format in which a track constituting one rotation of the disk is composed of an integer number of sectors. Wobbles of a predetermined integer number of cycles are added to the grooves in the zones, and wobbles of the respective cycles are aligned so that the wobbles of the respective cycles have the same phase between adjacent grooves in the respective zones. Each number is divided into a plurality of unit wobble strings, and the wobble in the unit wobble string is modulated to express binary information related to a sector address. The frequency of the wobble is controlled by a control frequency band of a tracking servo system. Set to be above and below the frequency band of the data signal Optical disc that features to be. 2. An optical disk drive for driving an optical disk according to claim 1, wherein a clock signal for data recording or a clock signal for data reproduction is generated by utilizing that the number of wobbles included in each sector is a predetermined integer number of cycles. An optical disc device characterized by the following.

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