JP3918799B2 - Optical disc and optical disc apparatus - Google Patents

Description

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

In an optical disc that manages recording and reproduction of data in units of sectors, a preformat ID method for preformatting identification information such as a track number and sector number of the sector at the head portion of each sector, that is, a sector ID in the form of a prepit, It is generally used for rewritable optical disks such as magneto-optical disks and phase change disks.
The advantage of the preformat ID method is that it is easy to manage data in units of sectors. Data is divided into 512 bytes, 2048 bytes, or the length of each recording / reproducing unit, 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 unit-length data follows the sector ID, access control can be easily performed.
Further, as a technology for increasing the capacity of an optical disk, data is recorded on both spiral guide grooves (also referred to as grooves) carved on the disk and flat portions (also referred to as lands) between the guide grooves. A so-called land / groove recording system is well known.

As a format of a large capacity optical disk, a land / groove recording optical disk with a preformat ID combining both of these has been studied.
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. Lands and grooves are used as data recording areas, and each sector consists of an ID area in which a sector ID is preformatted and a data area that follows the ID area.
Here, the groove track refers to a groove corresponding to one rotation of the disk starting from a predetermined radial line as a base point on the disk, and is composed of a continuous integer number of sectors. Similarly, the land track is a land corresponding to one rotation of the disk starting from a predetermined radial line as a base point on the disk, and is composed of a continuous integer number of sectors. Similarly, the track 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 as a base point on the disk.

In FIG. 15, data is recorded as recording marks on straight grooves and lands. A prepit ID indicating a sector ID is arranged near the boundary center between a pair of adjacent groove tracks and a land track, and both tracks share the same prepit ID. That is, the common pre-pit ID method.
This format has the advantage that the recording capacity can be increased by taking advantage of the features of land / groove recording, but it has inherited the advantages and disadvantages of the preformat ID format. There is a need to overcome the drawbacks and provide a more convenient optical disc format.

In the wobble groove ID method, which is another typical sector ID addition method, a so-called wobble is added in which the groove meanders in a predetermined amount from the track center in the disk radial direction perpendicular to the track direction. Further, there is a method of changing the meandering cycle 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 a CD-R that is a write-once compact disc (CD), a mini disc (MD) that is a rewritable optical disc, and the like.
However, since the wobble groove meander cycle is set to be very long compared to the bit length of the data, the accuracy of the wobble groove is rough when it is desired to determine the position of the sector having the sector ID read from the wobble groove. When attempting to manage data in units of sectors, it is necessary to provide a long buffer area between sectors, which is disadvantageous for increasing the capacity.

  FIG. 16 shows a track format of a conventional groove recording optical disk with a wobble groove ID. This is an example of groove recording for recording only in the groove. In the figure, data is written on the groove track as a recording mark. The groove has a wobble, and the wobble period is frequency-modulated to represent the track number and sector number of the sector. Therefore, as shown in FIG. 16, the wobbles vary depending on the location, Tw1, Tw2,. . . , Tw6 and so on.

Here, when applying the wobbled groove ID method in land / groove recording, it is possible to add a unique sector ID to the groove. However, in the sector on the land, the grooves on both sides Both wobbled grooves are meandering because they are meandering modulated in an uncorrelated manner, so that the edge of the information in either groove is meandering modulated by both the upper and lower groove wobbles. This can be understood from the fact that the ID signals are mixed and reproduced.
This disadvantage of difficulty in applying land / groove recording has become a major obstacle in increasing the capacity of optical disks of the wobbled groove ID system.

On the other hand, the advantage of the wobble groove method is that the groove meanders at a substantially constant period, so the rotation speed of the disk can be detected by detecting the wobble period from the tracking error signal, etc. It is easy to control the disk to a desired rotational speed by using it. Since this rotational speed is obtained from the disk surface itself for recording and reproducing data, it is more accurate than that obtained from, for example, a disk rotating motor.
Further, by multiplying the frequency of the wobble signal thus obtained, a synchronization signal and a clock signal used for data recording / reproduction 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 disc apparatus and the disc speed currently being rotated, and the redundancy of the sector format can be reduced. The recording capacity can be increased by the buffer area. This is an advantage that the wobble groove system has regardless of whether the groove meander period, 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 extending over the entire length of the sector so as to be superimposed on the data, so that even if the disk surface is dirty or scratched, the entire sector ID information is stored. There is an 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 concentrated and separated from data. Since this sector ID is shortened as much as possible in order to reduce the redundancy of the sector format, if there is dirt or scratches on the disk surface in the vicinity of the preformat ID, there is a probability that the entire sector ID information will be destroyed even if it is small. high. At this time, the sector becomes inaccessible even though the data recording area is usable. In a situation where a disk is used naked like a CD, there is a high possibility that many unusable sectors are generated in the disk.
In order to ensure the reliability of data by replacing such defective sectors, inspection of the entire disk surface, that is, certification is often performed at the time of manufacture. However, when considering the cost of the disk, the cost of the inspection time for the certification that takes a long time is a factor for increasing the disk price.
Alternatively, if data reliability is to be ensured with a low-priced disk shipped without certification, the user must perform certification before starting use. Depending on the recording capacity, this usually takes several tens of minutes to over an hour and is very inconvenient.

In a rewritable optical disk drive that drives a preformat ID optical disk, it is common to detect the disk rotation speed by attaching a rotary encoder to the motor for disk rotation control. It is a factor and also becomes a source of hindering motor thickness reduction.
Here, even if the rotation control of the disk is performed by using the preformat ID that appears periodically, the rotation speed is sufficiently accurate with only a preformat ID of only a few to several tens per disk rotation. It is difficult to control. Further, when some preformat IDs cannot be detected due to the above-mentioned dirt and scratches, the disk rotation becomes very unstable.

  Thus, the preformat ID method and the wobbled groove ID method have advantages and disadvantages contrary to each other. Here, if the features of both sides that are not in the other can be used in a complementary manner, sector recording can be performed with high efficiency, and there is reliability that can access the sector even if the disk surface is dirty or scratched. An optical disk that is high and easy to control rotation can be realized.

JP-A-6-176404

Since the conventional preformat ID type optical disk is configured as described above, it has the following problems.
When there is dirt or a flaw near the preformat ID, the entire sector ID information is crushed, and the probability of occurrence of a sector that becomes inaccessible even though the data recording area is usable increases.
In addition, there is a high possibility that many unusable sectors are generated in the disk under the situation where the disk is used naked.

It is necessary to perform a full inspection to ensure 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 data reliability with a disk that is not subjected to a full inspection, it is necessary for the user to perform a long-time certification before the start of use, which is very inconvenient.

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

Further, in a rewritable optical disc apparatus that drives a preformat ID type optical disc, the use of a rotary encoder for disc rotation control increases the cost.
This is also a source of obstructing the thinning of the device.

  It is necessary to provide a buffer area in the sector to absorb an error between the clock of the optical disk device and the rotating disk speed. For this reason, the sector format redundancy is increased, and the recording capacity is reduced by the buffer area.

  The present invention has been made to solve the above-described problems, and supplementally introduces the features of the wobbled groove ID system to an optical disk having a preformat ID system format, and provides data in units of sectors. Realizing a large-capacity optical disk that is easy to manage, can perform sector recording efficiently, has high reliability for accessing the sector even if the disk surface is dirty or scratched, and can easily control the disk rotation speed For the purpose.

  At the same time, it is an object of the present invention to reduce the price of an optical disc and an optical disc apparatus that drives the optical disc.

  In the present invention, the disk surface is divided into a plurality of zones according to the radial position, and is a zone format optical disk. A track that makes one rotation of the disk is composed of an integer number of sectors, and a preformat ID is assigned to each sector. In the land / groove recording format optical disk in which the preformat ID is arranged in the radial direction in each zone, a wobble of a predetermined integer number of cycles is added to the groove in each sector, and Then, the wobbles of each cycle are arranged to be in phase between adjacent grooves. However, the wobble is not necessarily the same frequency.

  In the second aspect of the present invention, the wobble of a predetermined integer cycle number added to the groove in each sector is further divided into a plurality of unit wobble strings for each predetermined unit cycle number in the optical disc, The binary information including the sector address information is expressed by modulating the wobble period. 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, as the sector number indicating the arrangement order of the sectors in the track to which each sector belongs, a value indicating the sector order when sequentially assigned from the end of the track is used. .

  In the fourth aspect of the present invention, in the optical disk apparatus for driving the optical disk, the rotation speed of the disk is controlled by utilizing the fact that the wobble included in each sector has a predetermined integer number of cycles.

  In the fifth aspect of the present invention, in the optical disk apparatus for driving the above-described optical disk, a data recording clock signal or a data reproduction clock is obtained by utilizing the fact that wobbles included in each sector have a predetermined integer number of cycles. Generate a signal.

  In the sixth aspect of the present invention, when the preformat ID of the sector cannot be read in the optical disk drive for driving the optical disk, the sector is accessed based on the sector address information read from the wobble of the preceding sector. To do.

  In the seventh aspect of the present invention, the polarity of the tracking servo is set based on the sector address information read from the wobble in each sector in the optical disk apparatus for driving the optical disk.

  The optical disc according to the embodiment of the present invention has a zone format, and a pre-format ID is added so that the sectors are aligned in the radial direction in the zone. A wobble with a predetermined integer number of cycles is added to each groove and the wobbles of each cycle are aligned in the same phase between adjacent grooves in each zone, so the wobble signal is accurate regardless of whether the groove is tracked or the land is tracked. Can be detected.

When binary information including sector address information is expressed by modulating and adding wobbles having a predetermined integer number of cycles to the groove in each sector of the optical disk, the track number to which the sector belongs is included as the sector address information. In addition, a zone number to which the sector belongs and a sector number indicating the arrangement order of the sectors in the track to which the sector belongs are included. At this time, the track number has a different value in the adjacent groove, but 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. Can receive the same wobble modulation and read the same wobble signal from the wobble grooves on both sides and reproduce the same information even in the land sandwiched between the wobbled grooves.
In this way, the wobbled groove ID is added to the optical disc in the land / groove recording format.

  In addition, the sector address information recorded in the wobbled groove ID displays a value indicating the sector order when the sector number indicating the arrangement order of the sectors in the track to which each sector belongs is sequentially assigned from the end of the track. 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. .

  In the detected wobble signal, since the wobble included in each sector has a predetermined integer cycle number, an error in the disk rotation number is detected and the disk rotation number is controlled.

  Since the wobble included in each sector is 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.

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

Embodiments of the present invention will be specifically described below 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 prior art according to the present invention. This land / groove shared address system will be described as a specific example. Lands and grooves are used as data recording areas, and each sector is composed of an ID area in which a sector ID is pre-formatted and a subsequent data area.

  In FIG. 1, data is recorded as recording marks on wobbled grooves and lands between the grooves. A prepit ID indicating a sector ID is arranged near the boundary center between a pair of adjacent groove tracks and a land track, and both tracks share the same prepit ID. The method for adding the prepit ID is not limited to this, but since the gist of the present invention is related to the method for adding the groove wobble, the following description will be given based on this conventional example.

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

  FIG. 2 shows another example of a land / groove recording optical disc with a preformat ID according to the present invention. As in FIG. 1, the groove wobble always meanders in the same direction by the same amount between adjacent sectors in the disk radial direction. However, this is an example in which the groove wobble period is changed on the sector. The point set so as to have the same period and the same phase as the adjacent groove does not change. While the wobble period of each cycle is different and the sector address information can be expressed, this wobble signal can be read even in the land sector between the grooves.

  FIG. 3 shows how the 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 track center is the groove center, and a signal indicating the 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, the polarity of the radial direction difference signal is assumed to be negative. Then, in the same way, the wobble of the groove also appears in the radial direction difference signal with a positive polarity when the radial meander is at the upper side and a negative polarity at the lower side.

In the example of FIG. 3, the setting is made such that 2 cycles of wobble are added to the ID area, 16 cycles of wobble are added to the data area, and 18 cycles of wobble are added to the entire sector. Usually, the wobble amplitude, which is the width of the meandering groove, 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-mentioned CD-R, the wobble amplitude is about 0.03 μm with respect to the track pitch of 1.6 μm. A very small amount of wobble amplitude in the present invention is set.
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 minute amount compared with the amplitude of the radial direction difference signal in the ID region. In FIG. 3, the wobble waveform is shown by a thin line in order to clearly indicate the number of wobble cycles in the ID area, but this portion is actually a negative polarity signal from the ID pit. At the time of manufacturing the disc, the ID pits in this portion may be meandered in the radial direction in the same manner as the groove, and preformat recording may be performed, or only 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.

  Now, the wobble signal detected in the data area is reproduced through a band filter and an amplifier that amplify only the wobble signal band, and 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. More precisely, it indicates the relative moving speed at which the light spot for recording / reproducing the disk scans the disk surface, that is, the disk linear velocity. This is shown in the wobble edge signal in FIG. When the wobble is engraved on the disk at a constant frequency, the wobble edge signal appears at a constant period. Therefore, the disk rotation motor is controlled so that this period becomes 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 a conventional preformat ID type disk having no wobble in the groove, the disk linear velocity can be detected with the appearance period of ID pits being 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 in the error reduction in the disk rotation speed control, the disk rotation speed can be controlled more accurately.
Also, the ID area is set to be very short on the disk compared to the data area. This is because the ID area is a redundant part that does not originally contribute to the data recording capacity, and is thus made as short as possible in the disk format design. For this reason, the ID area is relatively weak against disc dirt and scratches. When the ID pit cannot be detected due to dirt or scratches, the disc rotation is likely to become unstable if the disc rotation speed control is performed only by the ID pit. Groove wobbles can be detected on the entire surface of the disk except for the ID area, and there are a large number of them. If the groove wobble is used to control the rotational speed of the disk as a countermeasure against dirt and scratches on the disk, the proof strength is greatly enhanced and the reliability is improved. improves.
In ordinary rewritable optical disk devices, considering the rotational speed control accuracy and reliability, it is common to add a rotary encoder to the disk motor to detect the rotational speed of the disk, but wobble is added to the groove. This eliminates the need for this rotary encoder.

Here, the limiting condition for the wobble frequency will be described qualitatively. The limit on the low frequency side is defined by the tracking control band. If the wobble cycle is too long, the light spot follows the wobble by the tracking servo system, so that it becomes difficult to detect the wobble signal and an extra disturbance factor for the tracking control system. It is desirable to set the wobble frequency to a frequency that is about 10 times the bandwidth of the tracking control system. Generally, since the bandwidth of the tracking control system is about 10 to 20 kHz, the setting of the wobble frequency is about 150 kHz or more.
Further, the limit on the high frequency side is defined by the bandwidth 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 a 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 data signal can be set to be frequency-separated from the low-frequency spectrum. In general, since the band of the data signal has a peak at about 1 to several MHz, when the setting of the wobble frequency is considered to be about 1/10, the target is 100 kHz or less.

Further, generation of a recording / reproducing clock signal using a wobble signal will be described. As put to practical use in a sample servo optical disk, it has been realized to generate a clock signal for recording / reproducing data 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 is 300 times the period of the data channel clock frequency. A wobble signal detected from the disk surface is multiplied by 300 times by a phase synchronization circuit to generate a recording / reproducing clock signal.
If the wobble frequency can be set to about 1/100 or more of the channel clock frequency in this way, synchronization information can be obtained from the disk surface, and accurate clock generation and synchronization management can be realized. Actually, if the wobble frequency 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 apparatus such as a magneto-optical system, a crystal signal having a precise frequency is prepared for a channel clock and a clock signal is generated. On the other hand, the disk rotation control is not accurate as described above. When required, a precise and expensive rotary encoder is used to ensure synchronization between disk rotation and data channel frequency. If the disk rotation is relatively fast with respect to the data channel clock, the end of the sector is extended when recording, and the next sector is cut. In order to prevent this, a margin area to be a buffer is defined on a sector of the disk, and a method of keeping the margin area within an allowable range by managing each error has been adopted.

As described above, it has been found that if the wobble frequency is the same in all sectors, unprecedented features can be exhibited in the control of disk rotation and the generation of clock signals for recording and reproduction. However, as it is, it is impossible to realize the sector address information, which is another feature of the wobbled groove ID method.
In the wobble groove ID method, the wobble period, that is, the wobble frequency is modulated to express sector address information. In the present invention, since there is a constraint condition that the wobble is in phase with the adjacent groove as described above, the following method is considered when obtaining the modulation method of the wobble frequency.

First, a method is considered in which the wobble frequency is the same constant frequency between adjacent sectors in the radial direction of the disk and is different between the sectors in the circumferential direction. The number of wobble cycles in one sector is different. On the premise that one sector has the same length, this method is unacceptable due to a defect that the wobble period cannot be used for controlling the disk rotation speed.
Therefore, in the present invention, in a zone format optical disc, wobble modulation is performed using only sector address information that is the same among sectors included in each zone and aligned in the radial direction of the disc. . It is the zone number to which these sectors belong and the arrangement order of the sectors in the track to which these sectors belong. The track number is always different in adjacent grooves and 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 radial line as a base point on the disk, if the adjacent sectors are in the same zone, the arrangement order of the sectors in the track Are the same. This arrangement order of sectors is called a sector number. If there is no misunderstanding, the sector number is partial information included in the sector address information together with the zone number and the track number.

If a different sector number is assigned to each sector in one track, the track number cannot be identified by the wobble ID, but the sector number can be identified. In the state of continuous tracking, the track number does not change during one rotation, and the same track number is read from each sector. Even if reading of the preformat ID fails, it can be estimated with high probability. Thus, if the sector number is known from the wobble ID, the sector can be accessed without any problem unless reading of the pre-format ID fails continuously for one track. Originally, it is assumed that a complete sector ID is read from a preformat ID, and a wobble ID is to be used as a supplementing means. Therefore, it can be said that if there is such a function, it will play a sufficient role.
At this time, even in the land track sector on the optical disc of the land / groove recording format, the modulated grooves on both sides meander in completely the same phase, so the wobble waveform is accurately read and the sector address information is obtained. It became possible to play. Thus, it was possible to add a wobbled groove ID to an optical disc having a land / groove recording format.

Embodiment 2. FIG.
Next, the wobble signal waveform will be described. FIG. 4 shows a specific example of correspondence between binary information representing sector address information and a wobble signal waveform. The binarized information represented by the wobble modulated as described above is called a wobble information bit. Here, one wobble information bit is represented by a wobble signal waveform of eight cycles. For example, “0” is represented by a waveform in which four cycles of a low frequency (frequency: fL) LF waveform followed by four cycles of a high frequency (frequency: fH) HF waveform, and “1” is represented by a high frequency (frequency: fH). The LF waveform having a low frequency (frequency: fL) after 4 cycles of the HF waveform is represented by a waveform that continues for 4 cycles. In this way, the length of 1-bit wobble information bit is constant regardless of the information.
Also, the wobble waveform carved on the disk surface is almost sinusoidal. This is because the disc mastering device is designed so that it can be manufactured even if the response band of the deflection system for deflecting the cutting beam is not so high.

  As another example, FIG. 10 shows a wobble waveform carved on the disk surface in a substantially rectangular shape. This requires a slightly higher response band in the deflection system that deflects the cutting beam in the disc mastering device, but this level of wobble can be produced sufficiently if the device can cut the ID pit of the shared address method. 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 an 18-cycle wobble is added to the entire sector. The wobble in the ID area was not modulated.
In this example, the interval of the wobble edge signal changes every four cycles, and the interval of each edge signal is greatly different from the wobble period at the time of non-modulation which is a predetermined interval, but this is merely an example for conceptual explanation. When applied to an actual optical disc format, the interval between the edge signals can be set so as not to affect the accuracy of the disc rotation control and the accuracy of the generated clock signal. A numerical example will be described later.

An example of the format of sector address information represented by wobble information bits is shown in FIG. The meaning of each field is as follows. SYNC is a synchronization signal for capturing a read start point of sector address information, ZoneNo. Is the zone number, Sector No. 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 is an example of the length of wobble information bits assigned to each field. SYNC, ZoneNo. , Sector No. 8 bits and 16 bits for EDC are used, and 40 bits are used per sector as a whole. At this time, the zone can be expressed up to 127 zones, and the number of sectors in one track can be expressed up to 127 sectors, and the probability of missing a false detection can be reduced to 1/65000 or less. Note that the number of wobble information bits that can be actually set is determined by being limited by the format of the data sector and the wobble cycle.

7 and 8 show examples of sector number setting methods. As an example, a zone format disc is shown which is composed of 9 zones and numbered with zone numbers 0, 1,..., 8 in order from the inner zone. In the innermost zone 0, one track has eight sectors, and in the outermost zone 8, the number of sectors increases one by one. In the outermost zone 8, one track has 16 sectors.
In FIG. 7, sector numbers as the order of 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.
On the contrary, in FIG. 8, the sector numbers as the order of the sectors 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. By doing this, the end timing of each track can be easily detected regardless of the zone, so that it becomes very easy to use the sector number in the track format that requires servo processing at the track boundary. Next, an example will be described.
Although not shown, there is also a method of starting from 1 and assigning 2, 3,... As a sector numbering method. As a result, “0” can be used for special purposes such as a synchronization signal, or can be used to improve 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 disc. (A) is known as a general land / groove recording system, and a groove track is provided in a spiral shape on a disk. Therefore, since there are two spirals, a spiral composed of groove tracks and a spiral composed of land tracks, on the disk, this 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 a tracking error. On the other hand, if the tracking polarity is set to the land side, the land track is continued.

Therefore, no special consideration is required for switching the tracking polarity, as in the conventional simple groove recording and simple 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 every rotation of the disk to form a single spiral formed by connecting the groove track and the land track on the disk. This format is called land / groove (SS-L / G) recording. In SS-L / G, in order to continue the tracking continuously, it is essential to correctly detect the connection point between the land track and the groove track and to switch the tracking polarity for each rotation of the disk. Even if the preformat ID cannot be detected, this switching timing must be detected.
If the sector numbering method shown in FIG. 8 is used, the land track and groove track connection point can be read from the sector number recorded in the wobbled groove ID, and the sector number can be read. It is possible to know immediately whether or not it is a connection point or how close it is to the connection point without any arithmetic processing regardless of the current zone.

Embodiment 3 FIG.
A specific example assuming that the present invention is applied to an actual optical disc format will be described below.
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.
Assume that the sector length is 2697 bytes, 128 bytes are assigned to the ID area, 2569 bytes are assigned to the data area, and 2048 bytes of user data can be accommodated. The above information bytes are recorded and encoded using a recording code that converts 1 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 is 2048 channel bits (ch.bit), the data area is 41104 channel bits, and the entire sector is 43152 channel bits. Next, when wobble modulation in which 1 cycle (Cyc) wobble is inserted into 186 channel bits is applied and quantized so that the number of wobble cycles is a multiple of 8, it is 16 cycles in the ID region and 216 in the data region. 232 cycles of wobble can be added to the entire cycle and sector.

The wobble period is set to 186 channel bits because the entire sector needs to have a wobble cycle number that is a multiple of 8 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 the condition must be satisfied.
If 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 minimum signal frequency of the data system is 1.5 MHz. In order to reduce the wobble frequency to 1/10 or less of the lowest signal frequency of 1.5 MHz, the wobble frequency must be 150 kHz or less. On the other hand, since 150 kHz or more is required as a constraint condition from the tracking servo system, there is no wobble frequency other than around 150 kHz.
Further, since the sector channel bit length 43152 can be prime factorized to 3 × 31 × 29 × 16, when the whole sector is set to a wobble cycle number that is a multiple of 8, the remainder is (wobble period) × (wobble information bits). Number) = 2 × 3 × 31 × 29. Here, 186 = 2 × 3 × 31 channel bits are set as a wobble cycle, and the number of wobble information bits is set at 29 bits. Hereinafter, this example will be described. As can be seen from the current calculation, 174 = 2 × 3 × 29 channel bits can be used as the wobble period, and the number of wobble information bits can be set to 31 bits.

When the wobble period is 186 channel bits and the channel clock frequency is 30 MHz, the wobble frequency is about 161 kHz, which is exactly the above frequency constraint condition around 150 kHz. When the wobble period is 174 channel bits, the wobble frequency is about 172 kHz.
In this manner, 29 bits of wobble information can be represented by 232 cycles of wobble, but the ID area cannot be used in practice, and if the last bit of the sector is reserved as a buffer, the number of effective bits is wobble. The information bit numbers 3 to 28 are 26 bits.

FIG. 11 shows an example of wobble information bit allocation that takes into account this range. The role of the information bit field is the same as that shown in FIG. In each specific example, SYNC is 8 bits and EDC is 6 bits. Specific example-A shows a case where the zone number is 0 to 23 and the sector number is required up to 40 as information that needs to be expressed. At this time, ZoneNo. 5 bits, SectorNo. Requires 6 bits, for a total of 25 bits.
In Specific Example-B and Specific Example-C, the remaining 1 bit is set to ZoneNo. And Sector No. The case where it is attached to is shown. It is better to choose the one with a margin in consideration of the expandability to the future large capacity. If emphasis is placed on improving the linear recording density, Example-C is obtained.

An example in which the wobble information bits thus selected are arranged in the sector is shown in FIG. (A) shows the specific example-B. In (b), the resolution representing the zone is coarsened, and that amount is applied to the expandability of the sector number and the improvement of the error detection capability. In (c), the zone number is omitted and the error detection capability is further improved. In (d), a wobble referred to as “Clock” is provided before SYNC. This is a wobble period that is left as a portion that is not subjected to frequency modulation while leaving 186 channel bits per cycle. Since the interval between the wobble edge signals is constant, the circuit design can be facilitated and stabilized in the process of disc rotation speed control and clock signal generation. It aims at system stability rather than the amount of information content to be expressed.

Here, processing of the wobble signal when the recording capacity is expanded in the future or the disk rotation speed is increased 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 with the disc rotation speed kept the same. However, if there is no change in the logical format of the sector, that is, the allocation of data bits and wobble bits, the length of the wobble cycle measured by the distance is reduced by the increase in linear recording density, so the wobble frequency also increases. The ratio relationship with the channel clock frequency does not change.
In addition, when the disk rotational speed increases in proportion to the improvement in linear recording density, the control band of the tracking servo system increases, so the ratio relationship with the wobble frequency does not change. When the disk rotation speed increases with the same linear recording density, the control band of the tracking servo system approaches the wobble frequency, and the margin tends to decrease. However, since the above condition provides a margin of about 10 times, it is in a range that does not cause a problem unless the disk rotation speed is significantly increased.

FIG. 13 is a diagram for explaining restrictions on the degree of modulation 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 bits.
The state shown in the LF waveform (frequency: fL) is the waveform with the longest period allowed for the wobble signal. Maximum allowable period Tc. The length of 4 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 by the frequency synchronization circuit of the disk rotation speed control circuit or the clock signal generation circuit, it falls within the phase error detection window width, that is, enters the phase lock range. This is a necessary condition.
The state shown in the HF waveform (frequency: fH) is the waveform with the shortest period allowed for the wobble signal. Allowable minimum period Tc. The length of 4 min cycles must be at least 3.5 cycles 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 208 channel bits or less, Tc. It is necessary to set min to 164 channel bits or more.
For example, Tc. max is 200 channel bits, Tc. If min is 172 channel bits, the frequency modulation degree 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, since the rotation of the disk can be controlled using the wobble of the groove, which appears much more frequently than the preformat ID, it has become possible to perform the rotational speed control with sufficiently high accuracy.
Further, even when some preformat IDs cannot be detected due to dirt or scratches, it is possible to stabilize the disk rotation.
Further, in a rewritable optical disk drive that drives a preformat ID type optical disk, it is possible to remove the rotary encoder that is normally used for controlling the rotation of the disk, and the cost can be reduced.
At the same time, the rotary encoder can be removed to reduce the thickness of the disk motor, making it possible to reduce the thickness of the device.
In addition, in the optical disk, it is possible to reduce the buffer area provided in the sector in order to absorb the error between the speed of the rotating disk and the clock of the driving optical disk apparatus, and record data by the amount of the buffer area omitted. It became possible to increase the capacity.

In the second aspect of the present invention, in a zone format land / groove recording optical disk having a preformat ID in each sector, the wobbles may be modulated so that each cycle has the same phase between adjacent grooves in each sector. It became possible to add sector ID information by a wobble groove.
Utilizing this, the sector ID is duplicated and recorded in the preformat ID and the wobbled groove ID, so that the reliability of the disk can be greatly improved.
Even if the entire sector ID information is destroyed due to dirt or scratches near the preformat ID, it becomes possible to reproduce the sector address information from the modulated wobble, greatly reducing the probability of the sector becoming inaccessible. I was able to.
As a result, if the data recording area can be used, recording / reproduction to / from the sector becomes possible, and the reliability of the disk can be greatly improved.
In particular, it is possible to greatly reduce the possibility that unusable sectors are generated in the disk under bad conditions such as using the disk naked.
Furthermore, it is possible to omit the entire inspection that is performed to ensure the reliability of the preformat ID at the time of manufacturing the disk, and it is possible to reduce the inspection cost, which is the main factor of the disk price. The price can be reduced.
It is now possible to ensure data reliability with discs that are not fully inspected, and it is no longer necessary for users to certify for a long time before starting use, so that optical discs can be used very conveniently. .

In the optical disc of the third aspect of the present invention, detection of the tracking polarity switching timing at the connection point between the land track and the groove track, which is essential in the single spiral format land / groove recording optical disc having the preformat ID in each sector. Can be duplicated from the sector ID information recorded in the preformat ID and the wobbled 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 in the vicinity of the preformat ID. The probability of occurrence was significantly reduced.
As a result, it has become possible to greatly improve the reliability of data and devices by reducing the probability of failure that would cause tracking failure during continuous recording and cause data recording failure or destruction of recorded data. .

In the optical disc apparatus of the fourth aspect of the present invention, since the rotation of the disc can be controlled by using the wobble of the groove, which appears much more frequently than the preformat ID, it is possible to perform sufficiently high-precision rotation speed control. It was.
Further, even when some preformat IDs cannot be detected due to dirt or scratches, it is possible to stabilize the disk rotation.
Further, in a rewritable optical disk drive that drives a preformat ID type optical disk, it is possible to remove the rotary encoder that is normally used for controlling the rotation of the disk, and the cost can be reduced.
At the same time, the rotary encoder can be removed to reduce the thickness of the disk motor, making it possible to reduce the thickness of the device.

In the optical disk device of the fifth aspect of the present invention, it becomes possible to generate a clock signal for recording and reproduction in accordance with the synchronization information obtained directly from the surface of the rotating optical disk. It is possible to reduce the buffer area provided in the sector to absorb the error between the state and the clock of the optical disk device to be driven, and it is possible to increase the data recording capacity by the omitted buffer area. became.
In addition, it has become possible to avoid data destruction by overrunning the sector during recording due to an error between the rotational state of the disk and the clock of the optical disk device to be driven.
In this way, the reliability of the optical disk apparatus can be greatly improved.

In the optical disc apparatus of the sixth aspect of the present invention, it is possible to read the sector ID from both the preformat ID and the wobbled groove ID recorded in duplicate.
By using this, even if there is dirt or scratches near the preformat ID and the entire sector ID information is crushed, it becomes possible to reproduce the sector address information from the modulated wobble, and the sector which becomes inaccessible The probability of occurrence was significantly reduced.
As a result, if the data recording area can be used, recording / reproduction to / from the sector becomes possible, and the reliability of the disk can be greatly improved.
In particular, it is possible to greatly reduce the possibility that unusable sectors are generated in the disk under bad conditions such as using the disk naked.
Furthermore, it is possible to omit the entire inspection that is performed to ensure the reliability of the preformat ID at the time of manufacturing the disk, and it is possible to reduce the inspection cost, which is the main factor of the disk price. The price can be reduced.
It is now possible to ensure data reliability with discs that are not fully inspected, and it is no longer necessary for users to certify for a long time before starting use, so that optical discs can be used very conveniently. .

In the optical disc apparatus of the seventh aspect of the present invention, the tracking polarity switching timing at the connection point between the land track and the groove track, which is essential for a single spiral format land / groove recording optical disc having a preformat ID in each sector, is provided. The 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 in the vicinity of the preformat ID. The probability of occurrence was significantly reduced.
As a result, it has become possible to greatly improve the reliability of data and devices by reducing the probability of failure that would cause tracking failure during continuous recording and cause data recording failure or destruction of recorded data. .

  By the inventions as described above, the features of the wobbled groove ID method are introduced to the optical disc having the preformat ID format in a complementary manner to solve the problems of the preformat ID format, and the disc surface becomes dirty. Reliable access to sectors even if there is damage or scratches, easy disk rotation speed control, and ease of sector-by-sector data management and efficiency of sector recording, which are features of the preformat ID method A large-capacity optical disc that can be manufactured and its drive device can be realized at a low price.

  Although the above description has been made based on the so-called common pre-pit ID system, the gist of the present invention relates to the addition of wobble to a groove in a land / groove recording optical disk of the pre-format ID system in general. Accordingly, the applicable range of the present invention 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 preformat ID is different from the above.

It is a figure which shows the track layout of the optical disk which is Embodiment 1 of this invention. It is a figure which shows the track layout of the optical disk which is Embodiment 1 of this invention. It is a figure which shows the wobble signal of the optical disk which is Embodiment 1 of this invention. It is a figure explaining the modulation system of the wobble signal of the optical disk which is Embodiment 2 of this invention. It is a figure which shows the wobble signal which modulated the optical disk which is Embodiment 2 of this invention. It is a figure which shows the format of the wobble information of the optical disk which is Embodiment 2 of this invention. It is a figure which shows the sector number of the optical disk which is Embodiment 2 of this invention. It is a figure which shows the sector number of the optical disk which is Embodiment 2 of this invention. It is a figure which shows the track layout of the optical disk which is Embodiment 2 of this invention. It is a figure explaining the modulation system of the wobble signal of the optical disk which is Embodiment 2 of this invention. It is a figure which shows the format of the wobble information of the optical disk which is Embodiment 3 of this invention. It is a figure which shows the sector format of the optical disk which is Embodiment 3 of this invention. It is a figure explaining the modulation system of the wobble signal of the optical disk which is Embodiment 3 of this invention. It is a figure which shows the sector format of the optical disk which is Embodiment 3 of this invention. It is a figure which shows the track layout in the conventional land / groove recording system. It is a figure which shows the addition method of wobble ID in the conventional wobble groove recording system.

Claims (3)

A land / groove recording format optical disc in which a disc surface is divided into a plurality of zones according to a radial position, and a track that makes one rotation of the disc is composed of an integer number of sectors.
A wobble of a predetermined integer number of cycles is added to the groove in each sector,
Within each zone, the wobbles of each cycle are aligned in the same phase between adjacent grooves,
The wobble of the predetermined integer cycle number is divided into a plurality of unit wobble sequences for each predetermined unit cycle number,
The binary information related to the sector address is expressed by modulating the wobble period in the unit wobble sequence so that the phase between adjacent grooves is maintained in the same phase, and the binary information related to the sector address is expressed. An optical disc characterized by including a sector number indicating the arrangement order of sectors in a track to which each sector belongs. 2. An optical disc apparatus for driving an optical disc according to claim 1, wherein the polarity of the tracking servo is set based on the sector address information read from the wobble in each sector. 2. The optical disc apparatus for driving an optical disc according to claim 1, wherein rotation control of the optical disc is performed based on the binary information read from wobble.

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