JP2004213822A - Optical disk and optical disk drive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect address information by recording the address information as well as tracking marks in a servo area without lowering redundancy in a circular direction. <P>SOLUTION: A track is formed along a groove, servo information areas are intermittently provided for each segment, and data information areas are formed before and after the servo information areas. A track pitch Tp of a data information area has a period higher than that of an optical cutoff frequency. A tracking mark P1 is formed on extension lines of even tracks, and a tracking mark P2 is formed on extension lines of odd tracks. A segment address shows a position of one round in a rotating direction and has a constant value in a radial direction. The position of an edge of a groove in a data information area after the tracking mark P2 represents the position information of the segment in a rotating direction, that is, one bit of segment address information. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a sample servo type optical disk and an optical disk device.
[0002]
[Prior art]
In a conventional optical disk, a light spot from an optical pickup is tracked along a recording track formed spirally or concentrically on an information recording surface, and the return light of this light spot is detected by a photodetector, and the information is detected. Information is recorded or reproduced by reading pits formed on the recording surface. During tracking, a tracking error signal is generated by detecting return light of a light spot due to a groove or pit as a guide groove formed on an information recording surface of the optical disc, and a tracking error signal is generated based on the tracking error signal. By applying the tracking servo, an appropriate tracking state is secured.
[0003]
Various methods have been proposed and put into practical use for such a tracking error signal detection method and a tracking servo method. Among them, a tracking error signal is included in a disk rotation direction (also referred to as a track direction). A sample servo system in which a plurality of servo information areas for signal detection are provided intermittently is known. In one example of the sample servo method, servo information areas including three pits provided in advance by embossing or the like are provided at regular intervals in the circumferential direction. One pit is provided at a position coinciding with the center of each track, and the two pits provided before and after in the circumferential direction are at a fixed distance in the disk radial direction with respect to the track center and in the opposite direction. Each is provided at a separated position. These two pits are called wobbling pits.
[0004]
The reading position is controlled such that the levels of the reading signals generated when the recording / reproducing laser beam spot scans the two wobbling pits are equal to each other. Further, a reproduction clock can be stably generated by using a read signal of a pit formed on the track center.
[0005]
Assuming that the track pitch is Tp, the position of the two wobbling pits with respect to the track center is shifted, for example, by 1/4 Tp in one direction (for example, inside) in the disk radial direction with respect to the track center. The second wobbling pit is formed by embossing at a location, and is embossed at a location shifted by, for example, ４ · Tp in the other direction (eg, outside) in the disk radial direction with respect to the track center. By controlling the reading position of the laser beam so that the level of the reproduction signal when the spot of the laser beam crosses these marks becomes equal, the reading position can be made coincident with the track center.
[0006]
Generally, it is desirable to reduce the track pitch in order to increase the recording density. In the data area, data can be reproduced by a method such as MSR (Magnetically Induced Super Resolution) even if the track pitch is higher than the optical cutoff frequency of the spot light. However, if the distance between the two pits in the disk radial direction is narrow in the servo information area, it becomes difficult to detect a tracking error based on the reproduced signals of the two pits.
[0007]
The cutoff frequency fc is a frequency at which the degree of modulation becomes zero. It is determined by the NA (Numerical Aperture) of the objective lens and the laser wavelength λ, and is expressed as fc = 2NA / λ (number / mm).
[0008]
Therefore, an optical disk that enables normal tracking servo when the track density is increased is described in Patent Document 1 below.
[0009]
[Patent Document 1]
JP-A-10-79130
[0010]
In this document, two wobbling pits (hereinafter, appropriately referred to as tracking marks) are formed at a two-track cycle in the radial direction of the disk, and the positions where the tracking marks are formed are 180 ° out of phase. FIG. 1 shows an example in which a tracking mark is formed in a two-track cycle, and a broken-line square portion is shown in an enlarged manner. The optical disk 1 is provided with recording tracks along spiral or concentric grooves. A predetermined number of servo information areas are provided in the circumferential direction of the recording track, and tracking servo is performed using the servo information areas.
[0011]
In the data information area, a continuous groove is formed corresponding to all recording tracks, and in the servo information area, one of two adjacent recording tracks whose front and rear are surrounded by a mirror portion is recorded. One track groove is regularly thinned out for each servo information area. In the example shown in FIG. 1, the servo information area is formed at the same angular position in the circumferential direction from the inner circumference side to the outer circumference side of the optical disc, and is represented by radial lines S1, S2, S3,. It is arranged in a region on a straight line.
[0012]
In the servo information area, a first tracking mark P1 is formed on a track center of an odd track, and a second tracking mark P2 is formed on a track center of an even track. By forming each tracking mark in a two-track cycle, the interval between the tracking marks in the radial direction of the disk becomes 2 Tp, and a reproduction signal of a sufficient level corresponding to each tracking mark can be obtained.
[0013]
As shown in FIG. 2, the tracking marks P1 and P2 may be formed by shifting the tracking marks by 全体 Tp as a whole, and the phases of the tracking marks may be different by 180 °.
[0014]
As shown in FIG. 1, when the track and the tracking mark are formed, the amplitude change of the push-pull signal obtained by irradiating the spot Ls of the laser beam at each of the positions A, B and C is shown in FIG. Shown in For example, it is assumed that the diameter of the spot Ls is 2Tp. In FIG. 3, the vertical axis indicates the normalized amplitude, and the horizontal axis indicates the normalized radial position of the center of the spot Ls, that is, the radial deviation when the position coinciding with the track center is set to 0. . The radial position is normalized by the track pitch Tp. That is, a value of 1 means Tp. The push-pull signal is obtained by receiving return light by a light receiving element having two light receiving areas divided by a line that coincides in the circumferential direction, and calculating a difference between light receiving signals of the respective light receiving areas.
[0015]
As shown in FIG. 3, the amplitude of the push-pull signal obtained at the position A in the data information area is 0 irrespective of the radial position, and is obtained at each of the positions B and C in the servo information area. The amplitude of the push-pull signal is 0 at radial positions 0, 1, 2,..., And is maximum at radial positions 0.5, 1.5,. The push-pull signals obtained at each of the positions B and C are signals having opposite phases, and by subtracting the push-pull signal obtained at the position C from the push-pull signal obtained at the position B, A tracking error signal is formed.
[0016]
Further, as shown in FIG. 2, when the tracking marks are arranged so as to be entirely displaced by half the track pitch in the radial direction, the tracking error signal is detected by detecting the sum signal (total return light amount) of the spot light on the mark. Can be generated. FIG. 4 shows the amplitude change of the sum signal obtained by irradiating the laser beam spot Ls at each of the positions A, B and C when the track and the tracking mark are formed as shown in FIG. Is shown. For example, it is assumed that the diameter of the spot Ls is 2Tp. 4, the vertical axis indicates the normalized amplitude, and the horizontal axis indicates the radial position normalized by the track pitch Tp at the center of the spot Ls. The sum signal is obtained by adding the light receiving signals of the plurality of divided light receiving areas.
[0017]
As shown in FIG. 4, the amplitude of the sum signal obtained at the position A in the data information area is constant irrespective of the radial position, and is obtained at each of the position B and C in the servo information area. The amplitude of the sum signal changes according to the radial position. By subtracting the sum signal obtained at the position C from the sum signal obtained at the position B, a tracking error signal is formed.
[0018]
In the servo information area, segment address information and track address information are recorded. A segment means the smallest data unit on the optical disk, and a track means a data unit for one round consisting of a predetermined number of segments. For example, as shown in FIG. 5, one address mark P11 (for example, a pit by embossing) is formed between the tracking mark P2 and the data information area in the servo information area where the tracking marks P1 and P2 are formed. It has been proposed. The address mark P11 corresponds to, for example, one bit of the segment address. Although not shown, an address mark representing track address information is formed in a servo information area different from a servo information area in which segment address information is recorded.
[0019]
[Problems to be solved by the invention]
In such a method of providing a dedicated mark on address information, it is necessary to provide a mirror portion on which no mark is formed before and after the address mark in order to determine the presence or absence of the address mark. That is, three or more bits are required spatially. As a result, there is a problem that the recording density in the circumferential direction is reduced by the address marks and the front and rear mirror portions. Further, the address information of the track address is recorded at the same position as the address mark P11 in a servo information area different from the area where the segment address is recorded. Therefore, a process of separating and detecting the segment address and the track address is required, and there is a possibility that the reliability of the address detection may be reduced.
[0020]
Therefore, an object of the present invention is to provide an optical disk and an optical disk device capable of improving a recording density and detecting an appropriate address.
[0021]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, an invention according to claim 1 is directed to an optical disc in which tracks are provided in an annular shape at predetermined track pitches on an information recording surface on a disc substrate,
The track is formed along the groove, and the track has a data area for an information signal and a plurality of servo areas intermittently arranged in a part of the data area along the circling direction. The pitch is a period higher than the optical cutoff frequency of the spot light,
An optical disc in which a tracking mark for tracking detection is recorded in advance in each of a plurality of servo areas, and positional information of a division unit in a circumferential direction is recorded in advance by an edge position of a groove at the beginning or end of the data area. It is.
[0022]
According to a seventh aspect of the present invention, digital information is optically recorded on or read from a track provided on the information recording surface of the disk substrate at a predetermined track pitch in an annular manner. Optical disk device
The track of the optical disc is formed along a groove, and the track has a data area for an information signal and a plurality of servo areas intermittently arranged in a part of the data area along a circumferential direction,
The track pitch in the data area is set to a period higher than the optical cutoff frequency of the spot light,
In each of the plurality of servo areas, a tracking mark for tracking detection is recorded in advance, and position information of a division unit in the circumferential direction is recorded in advance by an edge position of a groove at the beginning or end of the data area,
A split photodetector that generates a read output by detecting return light of a laser beam applied to an optical disc;
Data detection means for detecting a reproduction signal from an output signal of the split photodetector,
A tracking control unit for generating a tracking error signal from an output signal of the split photodetector and correcting a reading position;
An optical disc device having position information detecting means for detecting position information of a division unit from an output signal of a division photodetector.
[0023]
In the present invention, the division information in the circumferential direction, for example, the position information of the segment is recorded in advance according to the edge position of the groove at the beginning or the end of the data area. Therefore, unlike the example shown in FIG. 5 in which mirror portions are arranged before and after a mark, the recording density in the circumferential direction can be improved.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The optical disk according to one embodiment is, for example, an MO (Magneto Optical: magneto-optical) disk in which tracks are formed in a spiral or concentric shape on an information recording surface thereof. In the data information area, continuous grooves are formed corresponding to all recording tracks. A digital signal is recorded along the groove.
[0025]
The groove is a surface close to a side on which a laser beam for reading is incident, and a portion between the grooves is called a land. In one embodiment, the digital signal is recorded in the groove, but the digital signal may be recorded in both the groove and the land. The pitch of the recording track is set to a period higher than the optical cutoff frequency of the spot light, and the recording data can be read by, for example, the MSR. The present invention can be applied not only to the MO but also to other types of optical disks such as a phase change optical disk, and further to a read-only optical disk.
[0026]
A servo information area is provided for each segment which is a data unit. On the optical disk, servo information areas are provided in a radially aligned manner. As will be described later, a tracking mark and an address mark are formed in the servo information error. In these marks, pits having a predetermined depth are formed corresponding to data values, similarly to the grooves. A mirror surface is formed in the servo information area where no mark is formed. The grooves and the marks are formed in advance on the substrate of the optical disc as in the steps of mastering, molding and film formation.
[0027]
In order to facilitate understanding of the optical disc according to the embodiment, first, a data structure of data recorded on the optical disc will be described with reference to FIG. As shown in FIG. 6A, one track includes, for example, 2100 segments. Therefore, one round of the optical disc is divided at an angle equal to 2100 areas. The present invention is also applicable to a zone CAV or a zone CLV in which a plurality of zones are formed from the inner circumference to the outer circumference of the optical disc and the angular velocity or the linear velocity is constant in each zone. For example, in the case of an optical disk having a zone CAV, one round in the zone is divided into areas having the same number of segments at equal angles.
[0028]
Segment numbers from 0 to 2099 are assigned to 2100 segments. All segments of one track are divided into nine segments. The unit of 9 segments is called a block. One servo information area is included for one segment. As described later, one servo information area includes two tracking marks and one address mark.
[0029]
As shown in FIG. 6B, nine address marks are included in each servo information area of nine consecutive segments on the track. As shown in FIG. 6C, the first eight address marks of the track are all "0", and the ninth address mark thereafter is X (X means either "0" or "1"). ). In the eight address marks in the second consecutive nine segments of the track, only the least significant bit is "1" and the other seven bits are "0". Bit X is recorded by the ninth address mark.
[0030]
As shown in FIG. 6D, an ascending block number is generated based on the address (8 bits) of a block including nine segments from the beginning of one track. The first block number is set to 0, and the last block number of one track is set to 231. That is, the relationship is 2100/9 = 232 (remaining 12 segments). The segment number is represented by the block number and the segment position in the block.
[0031]
As shown in FIG. 6E, the track address is, for example, 15 bits long. The address mark included in the ninth segment of each block represents one bit of the track address. Therefore, a track address is constituted by 15 bits represented by an address mark extracted from each of 15 consecutive blocks on a track. In the example of FIG. 6E, a track address in which all 15 bits are “0” is shown.
[0032]
The same track address is repeatedly recorded in one track to prevent an error. Since one track is 232 blocks, the same track address is repeatedly recorded seven times. Since 232/15 = 15 (the remainder is 7), multiplex recording can be performed 15 times. However, as will be described later, since the track address of the odd track and the track address of the even track are recorded separately, they are recorded. , The number of multiplex recordings is halved to seven.
[0033]
As described above, in one embodiment of the present invention, a segment address mark representing segment address information is recorded in eight servo information areas of nine consecutive segments on a track, and a ninth servo information area is recorded. Has recorded therein a track address mark representing track address information. The above numerical examples are merely examples, and an appropriate numerical value is selected in consideration of the total number of tracks included in one optical disc, the total number of segments per track, and the like. Further, as a measure against errors, encoding of an error detection code or an error correction code may be performed on the address information.
[0034]
Hereinafter, the servo information area in one embodiment will be described. FIG. 7 is an enlarged view of a rectangular portion indicated by a broken line of the optical disc 10. The servo information area is formed at the same angular position in the circumferential direction from the inner circumference side to the outer circumference side of the optical disc 10, and is arranged in a linear area as indicated by radial lines S1, S2, S3,. Have been.
[0035]
On the optical disc 10, recording tracks are formed along spiral or concentric grooves. As an example, a digital signal is recorded in a groove. In the groove of the track, for example, 2100 servo information areas are intermittently provided for each segment in the circumferential direction, and data information areas are formed before and after the servo information area. The track pitch Tp of the recording track in the data information area is set to be higher than the optical cutoff frequency of the spot light.
[0036]
In the data information area, a continuous groove is formed corresponding to all recording tracks, and no groove is formed in the servo information area. Therefore, mirror portions exist at both ends of each track. Further, a tracking mark and an address mark are formed on an extension of the groove in the data information area. As an example, the tracking mark P1 is formed on the extension of the track center of the even track, and the tracking mark P2 is formed on the extension of the track center of the odd track. By forming each tracking mark in a two-track cycle, the spacing between the tracking marks in the radial direction of the disc becomes 2 Tp, and a modulation signal for radial displacement can be obtained even if the track pitch Tp is higher than the cutoff frequency of the optical system. .
[0037]
Then, for example, by sampling and holding the push-pull signal at the position of the tracking mark P2, 2100 discrete tracking error signals are generated in one round. Further, by sampling and holding the push-pull signal at a position in the data information area, a tracking error signal having a phase shifted by 180 ° in the radial direction of the disk can be obtained. By taking the difference between these two tracking error signals, it is possible to obtain a tracking error signal that is less affected by the tilt of the optical disk and the field of view due to the lens position in a time division manner.
[0038]
The position of the optical disk 10 in the circumferential direction and the length of the mark are defined based on a reference clock signal at the time of recording. When the optical disk 10 is reproduced, a reference clock signal having the same phase as that at the time of recording is extracted from the reproduction signal (sum signal), and the level of the signal at a predetermined position in the circling direction is detected based on the reference clock signal. Can be.
[0039]
Next, the arrangement of information of the segment address and the tracking address will be described. FIG. 7 shows a configuration of a servo information area formed corresponding to eight segments out of nine segments in one block, in which segment address marks are formed. The segment address indicates the position of one rotation in the rotation direction, and is a constant value in the radial direction. Therefore, the positions of all the groove edges in the data information area are shifted by one clock for each segment.
[0040]
Based on the scanning order of the laser beam light spot Ls, the position information in the direction of rotation of the segment, that is, one bit of the segment address information is determined by the position of the edge of the groove of the recording track in the data information area behind the tracking mark P2. expressed.
[0041]
A groove G1 at edge position 1 for reducing the distance between the trailing edge of the tracking mark P2 and a front edge of the groove of the recording track, and a groove G0 at edge position 0 for increasing the distance are set. For example, the edge position 1 corresponds to one bit “1” of the segment address, and the edge position 0 corresponds to the “0”. As described with reference to FIG. 6, the segment address is 8 bits long, and each bit of the segment address is recorded as an edge position of each groove of segment numbers 0 to 7.
[0042]
FIG. 8 shows an arrangement of the servo information area when the track address information of the odd track is recorded. The track address has a length of, for example, 15 bits, and is recorded only in the segment of segment number 8 in units of 9 segments (that is, blocks). The track address information of the odd track is recorded as the length of the tracking mark P2. Since the value of the track address differs between radially adjacent tracks, it is recorded every other track.
[0043]
FIG. 8 shows an arrangement in which the length of the tracking mark P2 formed on the extension of the odd track is changed corresponding to one bit of the track address. In order to indicate the position where the segment number of each block is 8, a groove G-1 is formed in which the edge is at a position of -1 further behind the position of 0. The part given the reference symbol P3a indicates the part where the length of the tracking mark P2 is changed. For example, the tracking mark P2 has an extended portion P3a corresponding to the track address "1", and the tracking mark P2 has no extended portion P3a corresponding to the track address "0".
[0044]
As an example, the positions (1, 0, -1) of the three types of edges of the groove have a difference in length corresponding to one clock. Further, the amount of change in the length of the tracking mark P2 is also set to the length of one clock. One clock is a minimum amount and is a preferable amount for reducing the redundancy in the circling direction. However, another change amount such as two clocks may be used.
[0045]
FIG. 9 shows an arrangement in which a track address mark P3b is formed corresponding to one bit of a track address on an extension of an even track. In order to indicate the position where the segment number of each block is 8, the edge of the groove in the data information area is set to a position of -1 further behind the position of 0. The address mark P3b has a length of, for example, one clock, and has a length equal to the extension amount of the tracking mark P2 of the odd track described above. For example, the address mark P3b is formed corresponding to the track address "1", and the address mark P3b is not formed corresponding to the track address "0".
[0046]
As described above, the track address is 15 bits long, and 15 blocks (= 120 segments) are required to record one track address. For example, in 15 blocks where one track address is recorded, the track address of an odd track is recorded in an odd track, and in the next 15 blocks, the track address of an even track is recorded in an even track. As described above, the track address is recorded alternately on the odd track and the even track. In one round, each of the track address of the odd track and the track address of the even track is repeated about seven times.
[0047]
The above-described segment address information and track address information are converted into values of “0” or “1” by sampling and holding the sum signal level of the return light amount in the servo information area. As described above, the segment address is recorded by the change in the position of the groove edge, and the track address is recorded by the change in the length of the tracking mark. By recording the address information, the recording density in the circumferential direction decreases. Can be prevented.
[0048]
The segment address information may be recorded by changing the position of the rear edge of the groove in the front data information area.
[0049]
Next, an example of an optical disk apparatus using the optical disk according to the present invention will be described with reference to FIG. In FIG. 10, reference numeral 11 denotes a spindle motor for rotating the optical disk 10. FIG. 10 mainly shows the configuration of the apparatus during reproduction. At the time of recording, data is recorded on the tracks of the magneto-optical disk 10 by applying a modulation magnetic field corresponding to the recording data by the magnetic head 12 to the optical disk 10 while irradiating the optical disk with the laser light. The magnetic head 12 is driven by a drive signal according to the recording data from the magnetic head drive circuit 13. At the time of reproduction, data is reproduced by tracing a track with a laser beam using an optical head.
[0050]
Reference numeral 14 denotes a laser drive circuit, which drives a laser light source 15, for example, a semiconductor laser, and outputs laser light of a predetermined wavelength from the laser light source 15. The laser light from the laser light source 15 is converted into parallel light by the collimator lens 16, and is irradiated on the optical disk 10 via the beam splitter 17 and the objective lens 18. The return light from the optical disk 10 is guided from the beam splitter 17 to the beam splitter 19.
[0051]
The beam splitter 19 splits the return light from the beam splitter 17 into two optical paths, and the laser light from each optical path is incident on the respective light receiving surfaces of the photodetectors 20 and 21 divided into four via the condenser lens. . Outputs of the photodetectors 20 and 21 are supplied to a matrix circuit 23 via an I (current) V (voltage) conversion circuit 22. In the matrix circuit 23, output signals of the respective divided light receiving units of the photo detectors 20 and 21 are calculated.
[0052]
For example, a focus error is detected by an astigmatism method, and a focus error signal FE is formed. Further, the MO signal obtained by the matrix circuit 23 is supplied to the data detection circuit 24, and the push-pull signal PP is supplied to the tracking error generation circuit 25. Data reproduced from the data information area is obtained from the data detection circuit 24. The focus error signal FE and the tracking error signal are supplied to the phase compensation circuit 26.
[0053]
The phase compensation circuit 26 is provided for phase compensation of the servo system. The output of the phase compensation circuit 26 is supplied to a two-axis drive circuit 27. The objective lens 18 can be displaced in a disk radial direction (ie, a tracking direction) and in a direction perpendicular to the signal surface of the disk (ie, a focus direction). The two-axis drive circuit 27 drives a lens actuator (not shown) to perform tracking error correction and focus error correction. Further, although not shown, a spindle motor servo control circuit for controlling the spindle motor 11 and a thread servo control circuit for controlling the movement of the optical head in the disk radial direction are provided.
[0054]
Further, the RF (sum) signal formed by the matrix circuit 23 is supplied to the area detection circuit 28 and the address detection circuit 31. The area detection circuit 28 detects the servo information area and supplies the sum signal obtained in the servo information area to a PLL (Phase Locked Loop) circuit 29. The PLL circuit 29 generates a clock signal synchronized with the reproduction signal. The clock signal is supplied to the sample and hold timing generation circuit 30.
[0055]
The output of the sample / hold timing generation circuit 30 is supplied to the tracking error generation circuit 25 and the address detection circuit 31 as a sample / hold timing pulse. In the tracking error generation circuit 25, a push-pull signal or a sum signal in the servo information area is sampled and held at a predetermined timing necessary for detecting a tracking error. In the address detection circuit 31, the sum signal is sampled and held at a timing necessary for detecting the segment address information and the track address information in the servo information area. The address detection circuit 31 decodes the segment address information and the track address information based on the sample and hold output, and supplies these address information to a system controller (not shown).
[0056]
The system controller manages a recording position and a reproduction position on a recording track traced by the optical head and the magnetic head 12 based on the address information. A key input operation unit and a display unit are connected to the system controller, and control a recording system and a reproduction system in an operation mode specified by operation input information from the key input operation unit.
[0057]
In the above-described embodiment, the servo information area in which the segment address information is recorded and the servo information area in which the track address information is recorded are separated. However, these pieces of address information may be recorded in a common servo information area. FIG. 11 shows an example of the arrangement in this case. For example, a track address mark P3b is recorded on an extension of an even-numbered track. The segment address is recorded as a change in the edge position of the groove, for example, as a change in the position of 0 or -1. Although not shown, the segment address information is recorded in the same manner in the servo information area in which the length of the tracking mark on the extension of the odd track is changed.
[0058]
The present invention is not limited to the above-described embodiment of the present invention, and various modifications and applications are possible without departing from the gist of the present invention. For example, as shown in FIG. 2, the present invention may be applied to a servo information area arranged such that the tracking marks arranged as shown in FIG. 1 are shifted by Tp / 2 in the disk radial direction as a whole.
[0059]
【The invention's effect】
In the present invention, the division information in the circumferential direction, for example, the position information of the segment is recorded in advance according to the edge position of the groove at the beginning or the end of the data area. Therefore, unlike the arrangement of the mirror section before and after the address mark, the recording density in the circumferential direction can be improved. Further, since the track address information is recorded by changing the length of the tracking mark, the recording density in the circumferential direction can be improved unlike the case where the mirror section is arranged before and after the mark of the track address information. Further, in the present invention, since the position where the segment address information is recorded and the position where the track address information is recorded are separated, it is possible to improve the reliability of the address detection, It becomes possible to record both the segment address and the track address in the servo information area.
[Brief description of the drawings]
FIG. 1 is a schematic diagram illustrating an example of an arrangement of a servo information area of a conventional optical disc.
FIG. 2 is a schematic diagram illustrating another example of an arrangement of a servo information area of a conventional optical disc.
FIG. 3 is a schematic diagram illustrating an example of a push-pull signal for tracking detection.
FIG. 4 is a schematic diagram illustrating an example of a sum signal for tracking detection.
FIG. 5 is a schematic diagram for explaining a conventional method of recording address information in a servo information area.
FIG. 6 is a schematic diagram for explaining a data structure in the optical disc of one embodiment of the present invention.
FIG. 7 is a schematic diagram showing an arrangement of tracking marks and address marks in a servo information area according to an embodiment of the present invention.
FIG. 8 is a schematic diagram showing an arrangement of tracking marks and address marks in a servo information area according to an embodiment of the present invention.
FIG. 9 is a schematic diagram illustrating an arrangement of tracking marks and address marks in a servo information area according to an embodiment of the present invention.
FIG. 10 is a block diagram of an example of an optical disk recording / reproducing apparatus according to the present invention.
FIG. 11 is a schematic diagram showing an arrangement of tracking marks and address marks in a servo information area according to another embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Optical disk, 12 ... Magnetic head, 15 ... Laser light source, 20, 21 ... Photodetector, 23 ... Matrix circuit, 24 ... Data detection circuit, 25 ... Tracking error generation Circuit, 31 ... Address detection circuit, P1, P2 ... Tracking mark, P3a, P3b ... Mark representing track address, G1, G0 ... Groove having edge change representing segment address, G-1 ... Groove indicating servo information area of segment where track address is recorded

Claims (7)

An optical disc in which tracks are provided annularly at predetermined track pitches on an information recording surface on a disc substrate,
The track is formed along a groove, the track has a data area for an information signal, and a plurality of servo areas intermittently arranged along a circumferential direction in a part of the data area,
The track pitch in the data area is a cycle higher than the optical cutoff frequency of the spot light,
In each of the plurality of servo areas, a tracking mark for tracking detection is recorded in advance, and position information of a division unit in the circumferential direction is recorded in advance by an edge position of a leading or trailing groove of the data area. Optical disk. In claim 1,
The tracking mark is composed of first and second marks which are physically formed in advance at a predetermined distance in the circumferential direction,
An optical disc in which the first and second marks are provided at a two-track cycle in the disc radial direction, and the phases of the first and second marks in the disc radial direction are different. In claim 1,
An optical disc in which a plurality of grooves have the same edge position in the same radial direction. In claim 1,
An optical disc in which position information of a plurality of bits of the division unit is represented by the edge position of a groove included in a plurality of servo areas continuous in a circumferential direction. In claim 1,
Further, an optical disc in which track position information is recorded in advance by the length of the tracking mark included in the servo area. In claim 5,
One track position information is recorded on one extension line of two adjacent tracks, and the other track position information is recorded on the other extension line of the two tracks. An optical disc in which the servo area in which information is recorded and the servo area in which the other track position information is recorded are separated. An optical disc device in which digital information is optically recorded on tracks provided annularly at predetermined track pitches on an information recording surface on a disc substrate, or digital information is optically read from the tracks.
The track of the optical disc is formed along a groove, and the track has a data area for an information signal and a plurality of servo areas intermittently arranged along a circumferential direction in a part of the data area,
The track pitch in the data area is a cycle higher than the optical cutoff frequency of the spot light,
In each of the plurality of servo areas, a tracking mark for tracking detection is recorded in advance, and position information of a division unit in the circumferential direction is recorded in advance by an edge position of a leading or trailing groove of the data area. Yes,
A split photodetector that generates a read output by detecting return light of a laser beam applied to the optical disc;
Data detection means for detecting a reproduction signal from an output signal of the split photodetector,
A tracking control unit for generating a tracking error signal from an output signal of the split photodetector and correcting a reading position;
An optical disc device comprising: position information detecting means for detecting position information of the division unit from an output signal of the division photodetector.

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