METHOD FOR RECORDING ON DISC

Abstract: In a method for recording data on a disc, wherein digital data for servo-control is recorded beforehand on the disc into alignment in a radial direction, and the disc surface is divided into plural concentric zones, digital data having different clock rates are recorded on respective zones, reference data for sensing the quality of the recorded data is recorded on every recorded data area of one segment divided by servo-control data in all the zones. Thereby, the reproducing control for every zone in the event of zoning record can be performed easily.

Description: TECHNICAL FIELD The present invention relates to a disc recording method and, more particularly, to a disc recording method for use with a magneto-optical disc. BACKGROUND ART As a method for controlling a rotational speed of a discshaped recording medium when data is recorded and reproduced, there are known a constant angular velocity (CAV) control method in which data is recorded and reproduced at a constant rotational speed and a constant linear velocity (CLV) control method in which data is recorded and reproduced at a constant linear velocity. Comparing these two kinds of control methods, in the case of the constant angular velocity control method, the revolution rate per unit time is constant so that the speed can be controlled relatively easily. Also, control data such as a track address or the like are recorded on the same position in the diametrical direction so that the address search can be carried out with ease. On the other hand, in the case of the constant linear velocity control method, the rotational speed must be changed in response to the position of an optical pickup in the diametrical direction so that a speed control system becomes complicated. However, the recording density can be made constant and therefore an amount of recording information can be increased more than that of the constant angular velocity control method. However, the recording position of the control data such as the track address or the like is changed at every track. There is then the disadvantage such that the address search becomes cumbersome. In general, in most of the magneto-optical disc having large data recording capacity, in order to search necessary data with ease, data is recorded and reproduced by the constant angular velocity method in which the address search can be made with ease. However, as described above, the constant angular velocity control method is small in recording capacity as compared with the constant linear velocity control method. Therefore, as a method of increasing the recording capacity when data is recorded by the constant angular velocity control method, there is proposed a zoning recording method. FIGS. 1 and 2 show the condition such that the recording capacity is increased by this zoning method. FIG. 1 shows the example that the zoning recording is effected under the condition that the magneto-optical disc is divided into three zones A, B and C. FIG. 2 shows the example such that the zoning recording is effected under the condition that the magneto-optical disc is not divided into the zones (in the case of the constant angular velocity control method). In these examples, data is recorded on the discs in the form of pits. When the zoning recording is effected as shown in FIG. 1, the recording linear densities of innermost peripheral tracks T11, T21 and T31 of the respective zones A, B and C are set to be the same. within the respective zones A, B and C, the constant angular velocity control is effected (if the zone is changed, then a recording data clock frequency is changed) so that the recording linear density is lowered in the tracks of the outer peripheral side within the zone. If the magneto-optical disc is divided into a plurality of zones as described above, the linear recording density of one track can be returned to the highest condition each time the zone is changed. Thus, as compared with the case that the linear recording density is sequentially lowered to the outermost peripheral track when the magneto-optical disc is not divided into the zones as shown in FIG. 2, the recording capacity can be increased considerably. That is, although the outermost peripheral track provided when the magneto-optical disc is not divided into the zones is extremely low in linear recording density, if the magneto-optical disc is divided into a plurality of zones, then a sufficiently high linear recording density can be obtained even in the outermost peripheral track. In this case, by increasing the number of zones, the recording capacity can be increased much more. However, when the zoning recording is effected as described above, the control operation such as to extract a clock or the like in the playback mode must be switched at every zone. Therefore, in order to readily extract a reproducing clock or the like when the zone is switched, it is proposed that reference data that is used to detect the quality of a recording signal is recorded at every predetermined interval. However, when the above-mentioned zoning recording is effected in an optical disc of a so-called sample servo system in which servo control data are previously recorded in alignment with the diametrical direction of the disc in the form of convex and concave pits, a data capacity within one segment segmented by servo control data is made different between the respective zones so that the above-mentioned reference data and the recording data are continuously recorded within one segment. However, in the playback mode, after the reference data is reproduced, the playback control is effected on the basis of this reference data so that the playback of the recording data recorded immediately after the reference data becomes unstable. EP 0 390 601 A2 describes a disc recording method according to the preamble of claim 1. Furthermore, DE 38 09 223 A1 describes a method for optical recording information in which a system clock is used. Furthermore, JP-A-58166538 describes an optical reader in which the reliability of data reproduction is improved by detecting the amplitude of a specific pattern in a specific area of the recording data in each sector on a disc. DISCLOSURE OF INVENTION In view of the above-mentioned problems, the present invention is made and intends to provide a recording method in which recorded data can be reproduced easily and reliably even when the zone recording is effected. These problems have been solved by providing a disc recording method according to claim 1. With the method according to the present invention the control in a recording-system circuit and a reproducing-system circuit can be made easy. Furthermore, the system clock can be controlled with ease in each zone upon playback. Moreover, reference data can be detected with ease. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a schematic diagram used to explain the zoning recording; FIG. 2 is a schematic diagram used to explain the zoning recording; FIG. 3 is a diagram of a structure of a recording medium ; FIG. 4 is an explanatory diagram showing a general example of a format of each track; FIG. 5 is an explanatory diagram showing a general example of a track format of a zone A; FIG. 6 is an explanatory diagram skowing a general example of a track format of a zone B; FIG. 7 is a block diagram showing a recording and reproducing apparatus; FIG. 8 is a block diagram showing a main portion of the recording and reproducing apparatus shown in Fig 7; FIG. 9 is a block diagram showing a main portion of the recording and reproducing apparatus shown in Fig 7; FIG. 10 is a timing chart used to explain the timing upon reproduction; FIG. 11 is an explanatory diagram showing a data format of the zone B according to the only embodiment of the invention, FIG. 12 is an explanatory diagram showing an example of a data format of a zoning information area according to the embodiment shown in Fig 11, BEST MODE FOR CARRYING OUT THE INVENTION A general example will hereinafter be described with reference to FIGS. 3 to 10. This example is a magneto-optical disc in and from which data can be recorded and reproduced freely, and the magneto-optical disc is recorded in a zoning recording fashion as shown in FIG. 3. More specifically, on one magneto-optical disc, there are formed a plurality of concentric tracks. The magneto-optical disc is halved into a zone A formed of tracks near the center of the magneto-optical disc and a zone B formed of tracks near the outer peripheral tracks of the magneto-optical disc. In this case, when the radius of the magneto-optical disc is selected to be 32 mm, a range of the zone A falls within a radius of 16 mm to 22 mm and a range of the zone B falls within a radius of 22 mm to 30 mm. Within each of the zones, data is recorded and reproduced at a constant rotational angular velocity, and a recording data clock frequency for recording and reproducing is changed in the zones A and B (recording data clock frequency is higher in the zone B). One track of annular tracks within the respective zones A, B is formed of 990 segments as shown in FIG. 4. In this case, the segment of one unit is formed of a servo byte area of 4 bytes and a recording data area of 20 bytes (zone A) or 30 bytes (zone B). The 4-byte servo byte at the header portion of each segment is employed as a so-called pre-pit in which data is recorded on the disc in the form of pits. Upon recording and reproducing, a sample servo control is effected by data recorded on this pre-pit. Further, a track address and a sector address are recorded by the data from this pre-pit and then utilized upon access. On the recording data area of 20 bytes or 30 bytes following the servo byte area, there is recorded data by a circuit whose circuit configuration will be described later owing to a magneto-optical effect. A difference of recording capacity between 20 bytes and 30 bytes is caused by a difference between the recording data clock frequencies of the zones A and B. That is, by the zoning recording, the linear recording density of the innermost peripheral track of the zone A and the linear recording density of the innermost peripheral track of the zone B are set to be substantially the same. Accordingly, the recording capacity of the recording data area is changed at every zone in response to the length of the whole periphery of the innermost peripheral track of the zone. In the case of the zone A, as shown in FIG. 5, one sector is formed of 33 segments and one track forms 30 sectors. In the case of the zone B, as shown in FIG. 6, one sector is formed of 22 segments and one track forms 45 sectors. In this case, positions of the sectors are in alignment with one another within the respective zones. Accordingly, as shown by dashed lines in FIG. 3, boundary portions of the respective sectors exist within the respective zones in a radial fashion. When data is recorded, the recording is carried out in the unit of sectors. FIG. 7 is a diagram showing a circuit arrangement of a recording and reproducing apparatus for a magneto-optical disc to which the present invention is applied. Reference numeral 1 depicts a magneto-optical disc. On this magneto-optical disc 1, there is effected the zoning recording in which the recording is effected on the magneto-optical disc under the condition that it is divided into two zones of zones A and B as shown in FIG. 3. The magneto-optical disc 1 is rotated by a spindle motor 2 and recorded and reproduced by an optical pickup 3 which incorporates therein a semiconductor laser or the like. A rotation control of the spindle motor 2 and various controls (seek control, etc.) of the optical pickup 3 are effected by a system controller 4 formed of a microcomputer. Data recorded on this magneto-optical disc 1 is supplied from a recording data forming circuit (not shown) to a RAM control circuit 11 and then temporarily stored in a RAM 12 under the control of the RAM control circuit 11. The data thus stored is supplied from the RAM 12 to a modulating circuit 13 at a predetermined timing. The modulating circuit 13 modulates the data for recording and the recording data thus modulated is supplied to a write circuit 14. Then, this data is processed by this write circuit 14 in a predetermined write processing fashion. The recording data thus processed is supplied to the optical pickup 3 and is thereby recorded owing to the magneto-optical effect. The data thus written in the magneto-optical disc 1 is read out by the optical pickup 3 and then supplied to a read-out circuit 15. Then, the data, processed by the read-out circuit 15 in a predetermined read-out processing fashion, is supplied to a demodulating circuit 16. The data thus demodulated for playback by the demodulating circuit 16 is temporarily stored in the RAM 12. Then, the data thus stored in the RAM 12 is read out under the control of the RAM control circuit 11 and then supplied to a reproduced data output circuit (not shown) side. The detailed circuit arrangements of the read-out circuit 15 required in the playback mode and the peripheral circuits are illustrated in FIGS. 8 and 9. In this example, the magneto-optical disc 1 is recorded in a zoning recording fashion in which it is divided into two zones and therefore two kinds of read-out clocks are required. That is, FIG. 8 shows a circuit arrangement of a clock generating circuit. The reproduced signal supplied to the read-out circuit 15 and applied to a terminal 21 is supplied to a clock pit extracting circuit 22 and the servo byte data is extracted by this clock pit extracting circuit 22. The servo byte data thus extracted is supplied to a first PLL circuit (phase locked loop circuit) 23 and a second PLL circuit 24. In this case, the first PLL circuit 23 converts the input data into a signal of frequency 192 times as high as the original frequency. The signal having the frequency 192 times as high as the original one is supplied to a terminal 25 as a data detection clock of the zone A. Also, the second PLL circuit 24 converts the input data into a signal having a frequency (192 x 1.5) times, i.e., 288 times as high as the original one. Then, the signal having the frequency 288 times as high as the original one is supplied to a terminal 26 as a data detection clock of the zone B. A circuit arrangement of the read-out circuit 15 which extracts reproduced data on the basis of the thus formed clocks is illustrated in FIG. 9. The reproduced signal supplied to the read-out circuit 15 and applied to a terminal 31 is supplied to an AGC circuit (automatic gain control circuit) 32, an amplitude detecting circuit 33 and a clock phase detecting circuit 34. A reproduced amplitude of the reference data is detected by the amplitude detecting circuit 33 and a reproduced phase of the reference data is detected by the clock phase detecting circuit 34. Detection data of both the detection circuits 33, 34 are supplied to a central control apparatus (CPU) 35 that is used to control the read-out. On the basis of the amplitude detection data supplied thereto, the central control apparatus 35 controls an amount in which a gain of a reproduced signal is adjusted by the AGC circuit 32. Further, the central control apparatus forms correction data of read-out clock correction data on the basis of the clock phase detection data supplied thereto and supplies this correction data to a clock phase correcting circuit 39. The clock phase correcting circuit 39 phase-adjusts (phase-shifts) the data detection clocks obtained at the terminals 25 and 26 on the basis of the correction data and supplies any one of the thus adjusted clocks to a data detecting circuit 38. In this case, the clock supplied from the clock phase correcting circuit 39 to the data detecting circuit 38 is selected in response to the zone of the reproduced portion of the disc. More specifically, when the zone A is reproduced, the clock output from the first PLL circuit 23 is phase-corrected and then supplied to the data detecting circuit 38. When the zone B is reproduced, the clock output from the second PLL circuit 24 is phase-corrected and then supplied to the data detecting circuit 38. Therefore, when the track of the zone A is reproduced, reproduced data of servo byte is multiplied by 192 by the first PLL circuit 23 to provide a system clock and the signal having the original frequency becomes a read-out clock. Further, when the track of the zone B is reproduced, the reproduced data of servo byte is multiplied by 192 by the first PLL circuit 23 to provide a system clock that is used to effect the control based on the servo byte. Also, the reproduced data of servo byte is multiplied by 288 by the second PLL circuit 24 to provide a read-out clock. Then, the data detecting circuit 38 is supplied with the reproduced signal whose gain is adjusted by the AGC circuit 32, and decodes data recorded on the disc from the reproduced signal on the basis of the clock supplied thereto from the clock phase correcting circuit 39. The data thus decoded is supplied through a terminal 40 to a circuit of the succeeding stage as reproduced data. When the data recorded on the magneto-optical disc 1 is reproduced by the circuit thus arranged, the processing is carried out at the timings shown in FIG. 10. That is, as shown in FIG. 10A, during the reference data of the first segment of each sector is being reproduced, a reproduced amplitude of the reference data is detected by the amplitude detecting circuit 33 as shown in FIG. 10B. Also, the reproduced phase of the reference data is detected by the clock phase detecting circuit 34 as shown in FIG. 10C. Then, during the servo byte of the second segment is being reproduced, as shown in FIG. 10D, the reproduced amplitude and the reproduced phase are judged by the central control apparatus 35 to thereby control the gain adjustment amount of the AGC circuit 32 and the phase correcting amount of the clock phase correcting circuit 39. Then, under the condition that the gain adjustment and the phase correction are carried out as described above, as shown in FIG. 10E, the data recorded on the data area from the second segment is decoded. A sample servo control is effected at every segment on the basis of the data reproduced from the servo byte of each segment. When the reference data is reproduced by reproducing the next sector, the gain adjustment and the re-adjustment (recorrection) of the phase correction are similarly carried out on the basis of the reference data, whereby the adjustment (correction) of the reproduced state based on the reference data is carried out at every sector. In this case, according to this example, since the reference data is recorded on the whole interval of the first segment of each sector except the servo byte even though the reproduced track is any one of the zones A and B, as shown in FIG. 10, the data processing is carried out at the unit of segment and the reproducing processing can be carried out reliably under simple control. That is, the recording capacity of the servo byte is 4 bytes both in the zones A and B, whereby the timing control (switching control of servo byte and data area, etc.) of the playback processing can be carried out in any zone by using the system clock formed by the first PLL circuit 23 on the basis of the 4-byte reproduced data. Therefore, according to this example, in spite of the zoning recording, the timing control such as the switching of the servo byte and the data area or the like can be carried out commonly in the respective zones. In this case, since the recording state of the reference data is made at the unit of segment, the reference data detection timing also is made the same in the respective zones. Therefore, the control shown in FIG. 10 can be carried out at the same timing in any zone so that the playback processing utilizing the reference data can be carried out with ease. When the above-mentioned zoning recording is effected, it is desired that an information concerning the zoning can be obtained upon playback. Accordingly, in the case of the zone B, the recording may be effected as shown in FIG. 11 according to the only embodiment of the present invention. More specifically, a 1/3 of the first half of the recording data area of the first segment (first segment) of 22 segments constituting one sector is assigned to a zoning information area having a capacity of 10 bytes on which zone control data concerning the zoning recording of maximum 10 bits is recorded at a low recording ensity (i.e., 1/8 of the normal recording density) where one-byte area is employed as one bit, when data is recorded on this sector. A 2/3 of the second half of the data area of the first segment following this zoning information area is assigned to a reference area on which 20-byte reference data is recorded when data is recorded on this sector. The reference data of the zone B is similar to the reference data of the zone A. Then, in the data area from the second segment to the 22nd segment, data of 30 bytes each is recorded on the respective segments. Therefore, in the case of the zone B, 10-byte zone control data (in actual practice, 10-bit data by lowering the recording density to 1/8), 20-byte reference data and various data of 630 bytes (30 bytes x 21 segments) are recorded by one sector. An example of data recorded on the zoning information area of the first segment of each sector in the case of the zone B is illustrated in FIG.12. According to this only embodiment, zone control data up to 10 bits is recorded on the zoning information area having a recording capacity of 10 bytes at a low recording density in which the area of one byte is employed as one bit. Data representative of the number of zones is recorded on the 5-byte area of the first half of the zoning information area and zone running No. data is recorded on the second half 5 byte area. As the data representative of the number of zones, there is recorded data that represents the number of divided zones of this disc. When the zone is halved as, for example, shown in FIG. 3, data representative of the zone number 2 is recorded. In this case, since data up to 5 bits can be recorded, zone number data of 32 kinds at maximum can be recorded. The example of FIG. 12 shows the examples of data in the condition such that there are recorded four kinds of data of zone numbers 2, 4, 8 and 16. In this case, the above data can be recorded by 4 bits and other data can be recorded by remaining one bit. As the zone running No. data, there is recorded data that represents the zone to which the sector in which this data is recorded belongs. When the zone is halved as, for example, shown in FIG. 3, the zone running No. 1 (in the case of the zone A) or zone running No. 2 (in the case of the zone B) is recorded. In the case of the zone A, only the zone running No. 2 is recorded on the zone B because it has no zoning information area in actual practice. In this case, since data up to 5 bits can be recorded, zone running No. data of 32 kinds at maximum can be recorded. In the example of FIG. 12, there are shown examples of data representative of zone running Nos. 1 to 16. Also in this case, data can be recorded by 4 bits and other data can be recorded by remaining one bit. Then, in the reference area following the zone running No. data recording area, an information of about 8 bits can be recorded on one byte. According to this only embodiment, the zoning information area of the zone B is disposed in front of the reference area so that, even when the reproduced track is any of the zones A and B, after the 20-byte reference data is recorded on the first segment of each sector, only desired data can be recorded on all the data areas. Having neglected the servo byte, the reference data and the desired data are recorded under the common recording state in the respective zones and the common playback control can be effected in the respective zones. Therefore, in spite of the zoning recording, the playback processing can be carried out under simple control. Further, since the reference area of the zone B in the first segment is formed of 20 bytes similarly to the reference area of the zone A, the zoning information area is prepared in the area of remaining 10 bytes in which zone control data is recorded, a zoning condition and a zone running number of a reproduced portion can be detected from the data of this area, thereby making it possible to perform a playback control corresponding to a reproducing zone. In this case, data to be recorded in the zoning information area is recorded at a low recording density in which data is recorded by one bit each in the area of one byte so that, even when a read-out clock of the reproducing-system circuit is not synchronized with the recording signal, reproduced data can be discriminated sufficiently. There is then no disadvantage that even if such data is recorded in front of the reference data. While the zoning information area is provided in front of the reference data as described above, the present invention is not limited thereto and the zoning information area may be provided within the same segment following the reference data. In this case, since the zoning information is read out after the synchronization was carried out by the reference data upon reproduction, data need not be recorded at low recording density unlike the above-mentioned embodiment. In this case, however, an arrangement state of the reference data and the desired data (i.e., existence of zoning information between both data) is different in zones, which needs a countermeasure therefor. While the informations representative of the zone number and the zone running number are recorded in the zoning information area as described above, the present invention is not limited thereto and other informations concerning the recording mode may be recorded therein. While the zoning recording in which the magneto-optical disc is divided into the two zones is effected as described above, the present invention is not limited thereto and can be applied to the zoning recording where the magneto-optical disc is divided into three zones or three zones or more. Furthermore, it is needless to say that the present invention is not limited to the above-mentioned respective embodiment and various modifications could be effected therein.

Claims: Disc recording method comprising dividing the disc into a plurality of zones in the radial direction and recording digital data having different clock rates on every zone, recording servo control data on a disc in alignment with a radial direction from the innermost periphery to the outermost periphery, dividing said zones of said disc into a plurality of segments, whereby the number of segments segmented by adjacent servo control data within one track is the same in all zones, a byte number of data recorded within a segment is different at every zone and a plurality of segments constitute one data sector in said disc, characterized in comprising the steps of recording reference data on a recording data area of one segment of each sector for adjusting the gain and the system clock and recording zone control data on a zoning information area of said one segment of each sector of a zone representing the number of zones and a zone running number. The disc recording method according to claim 1, wherein said reference data is a reference signal that is used to control a phase of a data clock upon reproduction. The disc recording method according to claims 1 or 2, wherein said reference data is a pattern data having a repetitive constant frequency. The disc recording method according to any one of claims 1 to 3, wherein a rotational angular velocity of a disc is made constant in all zones and a recording is effected under the condition that a recording data clock is switched at every zone. The disc recording method according to any one of claims 1 to 3, wherein a recording data clock is made constant in all zones and a recording is effected under the condition that a rotational angular velocity of a disc is switched at every zone. The disc recording method according to any one of the preceding claims characterized in that said reference data is for adjusting the gain and/or phase of the recording signal. The disc recording method according to claim 6, wherein said zone control data represents the whole number of zones. The disc recording method according to claim 6, wherein a data amount of said reference data is equal in said all zones.

Inventors: SAKO YOICHIRO, WATANABE TETSU, YAMAGAMI TAMOTSU, SAKO, YOICHIRO, WATANABE, TETSU, YAMAGAMI, TAMOTSU, SAKO, YOICHIRO, SONY CORPORATION, WATANABE, TETSU, SONY CORPORATION, YAMAGAMI, TAMOTSU, SONY CORPORATION
Applicants: SONY CORP, SONY CORPORATION
Application year: 1992
Main classification: G11B20
IPC codes: G11B7, G11B11, G11B20, G11B27