JP3073746B2 - optical disk - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a track layout of an optical disk having both a rewritable area and a read-only area.

[0002]

2. Description of the Related Art When both a read-only area and a rewritable area are mixed on an optical disc, how to set a boundary between them is a problem. At the boundary between the read-only area and the rewritable area, if the two areas are too close, data confusion will occur, while if the two areas are separated, the utilization efficiency of the recording surface of the optical disc will be reduced.

A conventional example is disclosed in, for example, Japanese Patent Application Laid-Open No. 62-18 / 1987.
No. 4630 discloses an example in which both a read-only area and a rewritable area are provided on an optical disk as shown in FIG. In this example, both a read-only area and a rewritable area are provided on a rewritable recording film, and a CAV (Consta
The recording sectors are arranged in a sector layout of an nt angular velocity (nt angular velocity) system. The sectors in both areas have the same sector format in which a sector ID is added by a pre-format, and the boundary between both areas is continuous. The difference is that in the rewritable area, the data recording area is on a flat groove, whereas in the read-only area, the pre-format data has pits on the land surface, that is, pits with intermittent grooves. It is represented in the form of a column.

Japanese Patent Application Laid-Open No. 62-285232 discloses an example in which a guard area is provided at the boundary between a read-only area and a rewritable area provided on an optical disk as shown in FIG. This example is disclosed in Japanese Patent Application Laid-Open No. 62-18463.
At the boundary between the read-only area and the rewritable area having the same shape as that described in Japanese Patent Publication No. 0, an area called a guard area is set on both sides, and data is protected so as not to be used for actual data recording / reproduction. Techniques are disclosed.

In both of the examples, the grooves in the rewritable area and the pits in the read-only area have substantially the same width, and can be cut by the same beam during mastering of the master optical disc. Therefore, no special operation is required at the boundary between the rewritable area and the read-only area, and grooves and pits can be formed with predetermined dimensions simply by blinking the power of the cutting beam.

[0006]

SUMMARY OF THE INVENTION According to the present invention, in an optical disc having both a read-only area and a rewritable area, and both areas having different track formats, a track arrangement condition at a boundary portion is specified. It is an object of the present invention to provide a novel optical disc which prevents data from being confused in both areas and arranges both areas as close to each other as possible so as not to lower the utilization efficiency of the optical disc recording surface. Aim.

Another object of the present invention is to reduce the manufacturing cost and improve the yield of the master by reducing the adjustment and setting accuracy of the mastering device when mastering the master of the optical disk.

It is another object of the present invention to prevent a discontinuity in sector addresses from occurring at a boundary between a read-only area and a rewritable area.

[0009]

At the boundary between the read-only area and the rewritable area, the distance between the center of the last track of the read-only area and the track center of the first track of the rewritable area is equal to the distance between the read-only area and the rewritable area. The track pitches are arranged so as to be located in a predetermined range within a range of at least twice and at most 20 times the larger value of the track pitches.

In addition, at the boundary between the read-only area and the rewritable area, the end of the last sector of the read-only area and the start of the first sector of the rewritable area are arranged in contact with the same radius.

Further, the number is assigned so that the sector address of the last sector of the read-only area and the address of the first sector of the rewritable area are consecutive.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to the drawings. Embodiment 1 FIG. FIG. 1 shows an area layout of a disk surface of an optical disk to which the present invention is applied. This is an optical disc having both a read-only area and a rewritable area, and both areas having different track formats. A read-only area is arranged on the inner side of the disc, and a rewritable area is arranged on the outer side. In both areas, recording sectors are arranged in a sector layout of the CAV system. The present invention
A so-called ZCAV (Zone) in which at least one of the read-only area and the rewritable area is divided into a plurality of zones in the radial direction so that the recording density in each zone is substantially constant.
Although the present invention can be applied to optical discs having a format of the CAV (Cav) system in general, taking into account that the present invention relates to the shape of the boundary between the read-only region and the rewritable region, the CAV system will be used for simplicity of explanation. The following is described. Each sector has an ID area containing a sector address or the like at the beginning, followed by a data area containing rewritable data or read-only data. In the example shown in FIG. 1, one track of the read-only area is composed of, for example, 16 sectors, and one track of the rewritable area is composed of, for example, 12 sectors. Naturally, since the number of sectors per track is different, at the boundary between the read-only area and the rewritable area, the ID area of the read-only area and the ID area of the rewritable area may not be adjacent to each other.

FIG. 2 shows an enlarged view of a part of the boundary portion of such an optical disk. The track pitch of the read-only area and the track pitch of the rewritable area are substantially the same. At this time, a case is considered in which a so-called land / groove recording method is adopted as a recording method of the rewritable area, in which both a groove serving as a guide groove and a land between the grooves are used as recording tracks. Information is represented on the recording film in the form of recording marks. This situation is shown in the upper half of FIG. In order to record both land and groove with the same performance, the land width and the groove width are generally set to be substantially the same. When a phase change material such as GeSbTe is used for the recording film, the recording mark is represented by a difference in reflectance, and TbFeC
When a magneto-optical material such as o is used, the recording mark is represented by the direction of magnetization perpendicular to the recording surface. In either case, the presence of the recording mark is detected by a change in the amount of reflected light or a change in the polarization component, and the recorded information is reproduced.

The read-only area is a CD (Compact D)
Isc) and the like are used, and recording is performed using a concave pit row. This situation is shown in the lower half of FIG. The presence of recording pits is detected by a change in the amount of reflected light,
The recorded information is reproduced. The recording pits are formed together with the grooves in the rewritable area during mastering of the master optical disc. The track pitch is the center interval between adjacent pit rows. Therefore, when the track pitch of the read-only area and the track pitch of the rewritable area are substantially the same, the recording pit width is about half of the groove width. Regarding the pit width, if you make this too large,
The signal quality is degraded due to an increase in so-called crosstalk in which signals of adjacent tracks are mixed during reproduction. On the other hand, if it is too small, the reproduction signal level will not be sufficient, and it will be difficult to cut the master and form a disc.

The diameter d of the spot of the light beam used for recording / reproducing on the optical disk is substantially determined as d = (λ / NA) from the light wavelength λ and the numerical aperture NA of the condenser lens. λ = 63
In the case of 5 nm and NA = 0.6, d becomes about 1.06 μm. If the track pitch is narrowed to the permissible limit of the crosstalk, for example, 0.74 μm in order to increase the capacity of the disk, the light spot extends to a part of adjacent tracks on both sides of the target track. In the read-only area, both left and right ends of the spot protrude into adjacent tracks by 0.16 μm each. 0.4 μm recording pit width
Then, the recording pit is 0.2μ from the center of the recording track.
m, in other words, the recording pits are present only in the portions closer to the center by 0.17 μm or more from both ends of the recording track. Therefore, the foot of each spot of 0.16 μm protruding into the right and left adjacent tracks does not have to hit the recording pits of the adjacent tracks. If the groove width of the groove track in the rewritable area is 0.74 μm, the left and right hem of the spot also protrude into the adjacent land track by 0.16 μm each. Here, if recording is performed so as to limit the recording mark width to some extent, or if a method of setting the depth of the groove to about 1/6 of the light wavelength, which is known as a crosstalk canceling condition, is adopted, adjacent tracks can be used. Crosstalk can be canceled from. The same applies to the land truck.

However, in order to apply the crosstalk canceling condition, lands must be provided on both sides of a groove track, and grooves must be provided on both sides of a land track.
The land track at the boundary between the read-only area and the rewritable area cannot sufficiently cancel the crosstalk, and is therefore unsuitable for use as an information recording track. The land track included in the center of FIG. 2 with the track interval at the boundary indicates the unusable portion. FIG. 2 shows a case where the read-only area and the rewritable area are arranged closest to each other. If the lower side of the figure is the inner circumference of the disk and the upper side is the outer circumference of the disk, the distance between the track at the outer circumferential end of the read-only area and the track at the inner circumferential end of the rewritable area is:
As shown in the track interval at the boundary, the track pitch is twice as large as the track pitch of the other portions. This interval is 1.48 μm when the track pitch is 0.74 μm.

Now, consider a mastering process for producing such an optical disc. As described above, the recording pits and grooves are continuously cut during mastering of the master. When the groove width and pit width are different,
The light beam for cutting needs to be set thin when cutting the pit and thick when cutting the groove. In the cutting apparatus, since the optical system is adjusted with very high precision in order to precisely cut pits and grooves, and the light beam shape is set, it is difficult to change the setting of the optical system during cutting. Therefore,
When cutting pits or grooves of two different widths, it is convenient to use two light beams by adjusting and setting the beam diameter optimally to cut pits or grooves of each width. . The problem at this time is the accuracy of the alignment of the two beams. As described above, in order to adjust the track interval at the boundary between the track at the outer peripheral end of the read-only area and the track at the inner peripheral end of the rewritable area to 1.48 μm, the two beams are positioned with submicron accuracy. There is a need to. Generally, it takes time and effort to adjust or maintain the accuracy every time it is manufactured. This causes a reduction in the yield of the cut master and an increase in manufacturing cost.

FIG. 3 shows an embodiment in which the track interval at the boundary is enlarged as a means for relaxing the alignment accuracy of the two beams. In this figure, two unused tracks are provided at the boundary. With such a configuration, the allowable width of the track interval itself at the boundary may be increased. In this example, the position accuracy can be allowed up to 0.74 μm for one track. If the track interval at the boundary portion is further increased, the allowable width increases accordingly. However, since the use efficiency of the recording surface of the optical disc is reduced by an increase in the track interval at the boundary, the upper limit is set to a range in which there is no problem in the beam alignment accuracy. Above, two mastering mastering
Although a cutting device having the number of beams is assumed, the optical system can be variously configured with the same two-beam device as is known. When setting the track layout of the optical disk as described in this embodiment, it is preferable to loosely define the beam position accuracy so that the configuration of the optical system can be made as free as possible.

When considering the maximum width of the track interval at the boundary, another point to be considered is the seek operation in the radial direction in the optical disk device that drives this optical disk.
It is necessary to estimate or measure the light spot movement amount during the seek operation in the radial direction. It is a general method to count the number of track crossings from the waveform of the track crossing signal to obtain this movement amount. At this time, if there is a boundary where no track exists, an error occurs in the track crossing count number. When the crossing signal waveform suddenly stops appearing in the track crossing signal, it is often determined that the signal has been destroyed due to a medium defect, dust, or the like, and the crossing count number is often corrected. In this case, the track crossing count may be erroneously corrected at the boundary forming the mirror surface. Therefore, it is necessary to keep the track interval at the boundary within the allowable error range of the crossing count. There is. For this, it is desirable that even if the counting is wrong, the error can be recovered by one micro seek. Here, if the track count error is set to 20 or less, the object can be achieved with almost all optical disk devices. Normally, about 1 ms to jump one track
ec, so it takes about 20mse to jump 20
It takes time c. The time of about 20 msec corresponds to a rotation wait of one rotation of the disk when the disk rotation speed is 50 Hz. If the time required for recovering the track crossing number miscount is equal to or shorter than the rotation waiting time, it can be regarded as an allowable range.

In summary, the track interval at the boundary, which is the interval between the center of the last track of the read-only area and the center of the first track of the rewritable area, is set to a predetermined value within the range of twice to 20 times the track pitch. This means that it is better to arrange the values so that they are arbitrary within the range.
For example, in the above example in which the track pitch is 0.74 μm, the track interval at the boundary is set to 2
From 20 times to 20 times, the distance is 1.48 μm to 1
4.8 μm is an allowable range. That is, the relative position of the two beams of the master cutting device is set to 8.14 +/− 6.6.
The thickness may be set to 6 μm, and the setting error can be allowed up to 6.66 μm. This is a sufficiently loose condition for adjustment accuracy.
This width may be further limited as long as it meets the above-mentioned purpose. For example, in the same example in which the track pitch is 0.74 μm, if the track interval at the boundary is 2 to 8 times the track pitch, the allowable range is 1.48 μm to 5.92 μm. That is, the relative position of the two beams of the master disc cutting device is set to 3.7 +/− 2.2.
The thickness may be set to 2 μm, and a setting error can be allowed up to 2.22 μm. This is also a sufficient condition for adjustment accuracy.

Embodiment 2 FIG. An example in which the present invention is applied to a specific format of each sector of a read-only area and a rewritable area will be described. It is assumed that the entire optical disc has the track layout shown in FIG. FIG. 4 shows the sector shape near the boundary. The lower side of FIG. 4 corresponds to the inner peripheral side of the disk, and the tracks extend from the left side to the right side in FIG. This figure mainly shows a portion of one track where the end of each track is connected to the beginning of the next track. The sector in the read-only area has an ID area at the beginning and a data area in which read-only data is recorded after the ID area. The recording is the pit row recording described in the first embodiment. Since the recording tracks are continuous on one spiral, the recording tracks come to a position outside by one when the disk goes around once. The radius line shown in FIG. 4 is a radius in a certain direction assuming only one on the disk, and the head of each recording track is aligned on this radius. Of course, the head portion of the head sector of each track and its ID area are also arranged.

The configuration of tracks and sectors in the rewritable area is described in Japanese Patent Application No. 8-687 filed by the present inventors.
No. 33, etc., according to the single spiral land / groove recording format. In this format,
As in the normal land / groove recording described in the first embodiment, data is recorded on both land tracks and groove tracks, but there are two features. The first point is
It is a way of connecting groove tracks and land tracks. The groove track and the land track are alternately connected one by one to form one spiral. In other words, when the track starts from the radius line and goes around the disk for one round, the groove is connected to the land, and the land is connected to the groove. The second point is the arrangement of preformat signals in the ID area. The ID area is divided into two parts in the front and rear, and both are located on the boundary line between the land track and the groove track. It is arranged on the inner peripheral side with a half track pitch displacement.
The second half stores the sector address of a groove track that is shifted by a half track pitch, and the first half stores the sector address of a land track adjacent to the outer periphery of the groove track. By doing so, the tracks in the rewritable area are connected in a single spiral as a whole, and the sector addresses can be numbered in the order in which they are placed on the spiral.

FIG. 4 shows a case where the boundary between the read-only area and the rewritable area is arranged closest to each other, as shown in FIG. At the boundary between the read-only area and the rewritable area, the end of the last sector of the read-only area and the start of the first sector of the rewritable area are arranged on the same radius.
Since the leading portions of the leading sectors of the tracks in the read-only area and the rewritable area are aligned, even if the track interval at the boundary is the smallest, any part of the track around
The overlapping of the tracks in the read-only area and the rewritable area does not cause a collapsed portion of the track, or the tracks are too close to each other to cause data confusion.

FIG. 5 shows a case where the boundary between the read-only area and the rewritable area is arranged at a certain distance, as in FIG. The arrangement of the end of the last sector of the read-only area and the start of the first sector of the rewritable area in contact with the same radius line is the same as in the example of FIG. The boundary between the read-only area and the rewritable area is a ring-shaped mirror area on the disc. This mirror area is a boundary area, and its width is set as described in the first embodiment.

FIG. 6 shows a method of assigning sector addresses to the sectors of the read-only area and the rewritable area thus arranged on the disk. Like FIGS. 4 and 5,
Also in FIG. 6, the lower side corresponds to the inner peripheral side of the disk, and the tracks are continuous from the left side to the right side in the figure. When addresses are sequentially assigned from the inner peripheral side of the disk, a smaller address is assigned to a sector in the read-only area than to a sector in the rewritable area. As shown in FIG. 6, the numbers are assigned so that the sector address of the last sector of the read-only area and the address of the first sector of the rewritable area are consecutive. In this example, a sector address of 30000H is assigned to the first sector of the rewritable area. The sector address of the last sector of the read-only area is set to 2FFFFH, and the earlier sectors are assigned younger addresses in order. By doing so, it is possible to prevent discontinuity in the sector address at the boundary between the read-only area and the rewritable area. In the example of the address numbering method, one track is composed of 17 sectors in the rewritable area, and one track is composed of 18 sectors in the reproduction-only area. FIG. 1 illustrates a case where one track is composed of 12 sectors in the rewritable area and one track is composed of 16 sectors in the read-only area. However, the number of sectors can be appropriately set within the allowable range of the recording density. Of course, there may be cases where one track in both areas can be composed of the same number of sectors.

Thus, even if the boundary between the read-only area and the rewritable area is physically separated by a distance corresponding to several tracks, the sector addresses indicating the logical order of the sectors are continuous. Will be. If sector addresses are not continuous in a continuous sector address space, a problem occurs in an optical disk device that drives this optical disk. An error occurs in the calculation of the number of seek tracks at the time of access, so that the access time is extended, or an attempt is made to access a sector that does not actually exist on the disk, and a device failure occurs due to failure to reach. In addition, an access control program for a target sector becomes complicated, and a malfunction due to a program error is likely to be caused. It became possible to avoid such a point.

Embodiment 3 In an optical disc in which a read-only area and a rewritable area are mixed, the read-only area is often used as a control data area storing information on the format of the optical disc. When the optical disk device starts the optical disk, the track is first accessed to read parameters for servo control and signal recording / reproduction, and control parameters of the device are set. Thereafter, information can be recorded and reproduced in an optimal state. When the capacity of an optical disk is increased or the number of types is increased, in order to ensure compatibility in which one type of optical disk device handles other types of disks, the control data area must be readable from all optical disk devices. It is desired to keep. For this reason, the read-only area having the control data area has the same format even for optical discs of different types, and the format is changed only in the rewritable area. For example, the track pitch and the linear recording density are increased in order to increase the density. Can be considered. The logical format of the sector including the ID area and the data area may be the same or different between the read-only area and the rewritable area. In the rewritable area, a part that is not a reproduction-only area, such as a data pattern for securing the synchronization of a recording signal and a buffer area for securing a margin for disk rotation fluctuation, is required. By using the sector format dedicated to the read-only area, the recording capacity of the read-only area can be maximized.

FIGS. 7 and 8 show the case where the track pitch differs between the read-only area and the rewritable area. FIG.
3 shows an enlarged view of a part of the boundary when the boundary between the read-only area and the rewritable area is arranged with a certain distance therebetween, as in FIG. An example in which the track pitch of the read-only area is 0.74 μm as described in the first and second embodiments, and the track pitch of the rewritable area is smaller than the track pitch of the read-only area, for example, 0.37 μm, which is almost half, It is. FIG. 8 shows a sector shape near the boundary when the boundary between the read-only area and the rewritable area is arranged at a certain distance, similarly to FIG.

In such a case, the setting of the track interval at the boundary between the read-only area and the rewritable area is set to at least twice the larger of the track pitches and 2 times.
One method is to define the arrangement within a predetermined range included in a range of 0 times or less. In this way, even when the track interval at the boundary is minimized, crosstalk from an adjacent track can be suppressed within an allowable range.

This has an advantage even when the mastering process of the master is considered. Usually, when cutting a master, a recording light beam, that is, a groove or a pit row is formed by sending a cutting light beam in the radial direction while rotating the master. When the track pitch is different between the read-only area and the rewritable area of the disc, it is necessary to switch the speed at which the beam is sent in the radial direction at the boundary between the two areas. Here, if the track interval at the boundary is longer than necessary for switching the feed speed, switching can be performed while passing through this part, so tracks in each area must be cut accurately at the specified track pitch. Can be. As described above, the track interval at the boundary between the read-only area and the rewritable area is set within a predetermined range within a range of not less than twice and not more than 20 times the larger value of the respective track pitches. If a sufficient time is provided, it is possible to secure the time required for switching the feed speed.

Embodiment 4 FIG. In the third embodiment, there is shown an example in which the read-only area has a track pitch of 0.74 μm and the track pitch is increased only in the rewritable area in order to increase the density in an optical disk in which a read-only area and a rewritable area are mixed. However, here, as a similar example, a case where the track pitch of the rewritable area is set to 0.6 μm is shown. In this case, the groove width is also 0.6 μm. Here, if the pit width of the read-only area is set to 0.5 μm, which is slightly wider than substantially half the track pitch, the difference from the groove width of the rewritable area of 0.6 μm is reduced. Since the groove width is about 1.2 times the pit width, cutting with one beam can be performed depending on the performance of the master cutting device. When cutting is performed with one beam, there is no problem in the accuracy of alignment of the two beams. Therefore, it is desirable to arrange the read-only area and the rewritable area as close as possible. This is because it is advantageous for avoiding a miss count at the time of seeking.

Even in such a case, the allowable range of the track interval at the boundary between the read-only area and the rewritable area is included in the range of twice or more and 20 times or less of the larger track pitch among the track pitches. In a one-beam cutting apparatus with the best cutting accuracy, it is possible to minimize the track interval at the boundary in the same manner as shown in FIGS. 2 and 4. it can. In this way, it is possible to use the effect of the continuity of the sector address without reducing the access performance while keeping the crosstalk from the adjacent track within the allowable range.
It is of course possible to use a two-beam cutting device within the allowable range of cutting accuracy.

[0033]

Since the present invention is configured as described above, it has the following effects. At the boundary between the read-only area and the rewritable area, the radial distance between the last track of the read-only area and the first track of the rewritable area is the larger of the respective track pitches of the read-only area and the rewritable area. More than twice the value and 2
By stipulating that the tracks are arranged in a predetermined area within the range of 0 times or less, the tracks in the read-only area and the rewritable area are too close to each other, which may cause the track to be destroyed, or cause confusion of data with each other. You can now avoid doing so.

At the same time, it is also possible to avoid that the tracks in the read-only area and the rewritable area are too far apart to produce a useless area, thereby lowering the use efficiency of the recording surface of the optical disk. At this time, by limiting the width of the portion where no track exists to a predetermined range, it is possible to limit an error generated in estimating the movement amount of the light spot during the seek operation in the radial direction in the optical disk device that drives this optical disk. It was possible to improve seek accuracy. As a result, the access time between tracks in the read-only area and the rewritable area can be reduced.

In the mastering apparatus for mastering the master of the optical disk, the setting accuracy of the relative position between the beam for cutting the read-only area and the beam for cutting the rewritable area can be relaxed. The load for adjustment for setting is reduced, and the manufacturing cost can be reduced. Alternatively, the master can be cut as long as the relative position of the two beams can be adjusted within the predetermined range, so that the configuration of the master mastering device is more free and easy. At the same time, the production yield of the master can be improved.

Further, at the boundary between the read-only area and the rewritable area, the end of the last sector of the read-only area and the start of the first sector of the rewritable area are arranged so as to be in contact with the same radius. When the rewritable area is mastered closest, the tracking can be smoothly continued without moving in the radial direction from the last sector of the read-only area to the first sector of the rewritable area. At this time, it is possible to avoid a situation in which only a part of a track in the read-only area and a part of the track in the rewritable area overlap with each other, resulting in a broken part of the track.

Furthermore, since the sector address of the last sector of the read-only area and the address of the first sector of the rewritable area are numbered consecutively, they do not actually exist on the disk in a continuous sector address space. Sectors could not appear. As a result, in the optical disk device that drives this optical disk, it is easy to simplify the access control program to the target sector and to avoid malfunction due to a program error.

An optical disk having a rewritable area of the single spiral land / groove recording format has a feature that the arrangement order of the sectors is physically and logically continuous even though the land / groove recording is performed. Have. By applying the present invention to a case where a read-only area is additionally provided on a disk of this format, it is possible to maintain the feature that the arrangement order of sectors is logically continuous.

Further, in an optical disk using a read-only area as a storage area for control data, in the future,
When producing a disc with a different track pitch between the read-only area and the rewritable area by reducing the track pitch of the rewritable area to increase the capacity, the tracks with different track pitches are used for both areas during mastering of the master. , It was possible to accurately secure the track pitch in each region.

In the above description, it has been described that the read-only area is arranged on the inner side and the rewritable area is arranged on the outer side, and the sectors are arranged in order from the inner side to the outer side. Needless to say, the gist of the present invention is not limited to this form. The same method can be applied to an optical disk in which sectors are arranged in order from the inner circumference to the outer circumference, in which the rewritable area is arranged on the inner circumference and the read-only area is arranged on the outer circumference. It demonstrates. Further, in an optical disc in which sectors are arranged in order from the outer circumference to the inner circumference, the read-only area is
The same method can be applied to various deformations such as a case where the rewritable area is arranged on the inner peripheral side, and the same functions and effects are exhibited. Further, the present invention provides a read-only area,
At least one of the rewritable areas is divided into a plurality of zones in the radial direction to make the recording density in each zone substantially constant,
In general, an optical disc having a so-called ZCAV (Zone CAV) format can be applied to a boundary between a read-only area and a rewritable area on the disc,
It goes without saying that the same effect is exhibited.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an area layout of an optical disc according to a first embodiment of the present invention;

FIG. 2 is an explanatory diagram of a track shape of the optical disc according to the first embodiment of the present invention.

FIG. 3 is an explanatory diagram of a track shape of the optical disc according to the first embodiment of the present invention.

FIG. 4 is an explanatory diagram of a sector arrangement of an optical disc according to a second embodiment of the present invention;

FIG. 5 is an explanatory diagram of a sector arrangement of an optical disc according to a second embodiment of the present invention;

FIG. 6 is an explanatory diagram of a sector address numbering method for an optical disc according to the second embodiment of the present invention.

FIG. 7 is an explanatory diagram of a track shape of an optical disc according to a third embodiment of the present invention.

FIG. 8 is an explanatory diagram of a sector arrangement of an optical disc according to a third embodiment of the present invention.

FIG. 9 is an explanatory diagram of an area layout of a conventional optical disc.

FIG. 10 is an explanatory diagram of an area layout of a conventional optical disc.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-10-105977 (JP, A) Kazuhiko Nakane, 6 others, "Access method for single spiral land-groove recording", Television Technical Report, On February 29, 1996, Vol. 20, No. 16, pp. 29 −34 (58) Field surveyed (Int.Cl. ⁷ , DB name) G11B ^7/ 00-7/013 G11B 7/30 G11B 20/12 G11B 7/24

Claims (1)

(57) [Claims] In an optical disc having both a read-only area and a rewritable area, and both areas having different track formats, the end of the last sector of the read-only area and the start of the first sector of the rewritable area are determined. When the track pitch of the read-only area is different from the track pitch of the rewritable area, the track center interval between the last track of the read-only area and the top track of the rewritable area is set to one of the following. It is arranged so as to be located within a predetermined range included in a range of not less than twice and not more than 20 times of the larger track pitch, a boundary portion between the two regions is a mirror surface, and An optical disc characterized in that the sector address of the last sector and the address of the first sector of the rewritable area are numbered consecutively.